This patch-set introduces the possibility of protecting memory that has
been allocated dynamically.
The memory is managed in pools: when a memory pool is turned into R/O,
all the memory that is part of it, will become R/O.
A R/O pool can be destroyed, to recover its memory, but it cannot be
turned back into R/W mode.
This is intentional. This feature is meant for data that doesn't need
further modifications after initialization.
However the data might need to be released, for example as part of module
unloading.
To do this, the memory must first be freed, then the pool can be destroyed.
An example is provided, in the form of self-testing.
Changes since v17:
* turned all BUGs into WARNs, with the exceptions of the (optional)
genalloc selftesting
* added mode descriptive messages, in case of failures
* fixed incorrect description of behavior when destroying a pool
* added tetst case of allocating memory from protected pool
* fixed kerneldoc description also for genalloc.h
* added missing Kconfig dependency for pmalloc, on MMU
* fixed location of initialization of link page struct -> vm_area
Igor Stoppa (7):
genalloc: track beginning of allocations
genalloc: selftest
struct page: add field for vm_struct
Protectable Memory
Pmalloc selftest
lkdtm: crash on overwriting protected pmalloc var
Documentation for Pmalloc
Documentation/core-api/index.rst | 1 +
Documentation/core-api/pmalloc.rst | 111 ++++++
drivers/misc/lkdtm.h | 1 +
drivers/misc/lkdtm_core.c | 3 +
drivers/misc/lkdtm_perms.c | 28 ++
include/linux/genalloc.h | 367 +++++++++++++++---
include/linux/mm_types.h | 1 +
include/linux/pmalloc.h | 242 ++++++++++++
include/linux/test_genalloc.h | 26 ++
include/linux/test_pmalloc.h | 24 ++
include/linux/vmalloc.h | 1 +
init/main.c | 4 +
lib/Kconfig | 15 +
lib/Makefile | 1 +
lib/genalloc.c | 745 +++++++++++++++++++++++++++----------
lib/test_genalloc.c | 410 ++++++++++++++++++++
mm/Kconfig | 17 +
mm/Makefile | 2 +
mm/pmalloc.c | 468 +++++++++++++++++++++++
mm/test_pmalloc.c | 100 +++++
mm/usercopy.c | 33 ++
mm/vmalloc.c | 2 +
22 files changed, 2364 insertions(+), 238 deletions(-)
create mode 100644 Documentation/core-api/pmalloc.rst
create mode 100644 include/linux/pmalloc.h
create mode 100644 include/linux/test_genalloc.h
create mode 100644 include/linux/test_pmalloc.h
create mode 100644 lib/test_genalloc.c
create mode 100644 mm/pmalloc.c
create mode 100644 mm/test_pmalloc.c
--
2.14.1
The genalloc library is only capable of tracking if a certain unit of
allocation is in use or not.
It is not capable of discerning where the memory associated to an
allocation request begins and where it ends.
The reason is that units of allocations are tracked by using a bitmap,
where each bit represents that the unit is either allocated (1) or
available (0).
The user of the API must keep track of how much space was requested, if
it ever needs to be freed.
This can cause errors being undetected.
Examples:
* Only a subset of the memory provided to an allocation request is freed
* The memory from a subsequent allocation is freed
* The memory being freed doesn't start at the beginning of an
allocation.
The bitmap is used because it allows to perform lockless read/write
access, where this is supported by hw through cmpxchg.
Similarly, it is possible to scan the bitmap for a sufficiently long
sequence of zeros, to identify zones available for allocation.
This patch doubles the space reserved in the bitmap for each allocation,
to track their beginning.
For details, see the documentation inside lib/genalloc.c
The primary effect of this patch is that code using the gen_alloc
library does not need anymore to keep track of the size of the
allocations it makes.
Prior to this patch, it was necessary to keep track of the size of the
allocation, so that it would be possible, later on, to know how much
space should be freed.
Now, users of the api can choose to etiher still specify explicitly the
size, or let the library determine it, by giving a value of 0.
However, even when the value is specified, the library still uses its on
understanding of the space associated with a certain allocation, to
confirm that they are consistent.
This verification also confirms that the patch works correctly.
Eventually, the extra parameter (and the corresponding verification)
could be dropped, in favor of a simplified API.
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/genalloc.h | 354 ++++++++++++++++++++---
lib/genalloc.c | 721 ++++++++++++++++++++++++++++++++++-------------
2 files changed, 837 insertions(+), 238 deletions(-)
diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index 872f930f1b06..7b1a1f1d9985 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -32,7 +32,7 @@
#include <linux/types.h>
#include <linux/spinlock_types.h>
-#include <linux/atomic.h>
+#include <linux/slab.h>
struct device;
struct device_node;
@@ -76,7 +76,7 @@ struct gen_pool_chunk {
phys_addr_t phys_addr; /* physical starting address of memory chunk */
unsigned long start_addr; /* start address of memory chunk */
unsigned long end_addr; /* end address of memory chunk (inclusive) */
- unsigned long bits[0]; /* bitmap for allocating memory chunk */
+ unsigned long entries[0]; /* bitmap for allocating memory chunk */
};
/*
@@ -93,10 +93,40 @@ struct genpool_data_fixed {
unsigned long offset; /* The offset of the specific region */
};
-extern struct gen_pool *gen_pool_create(int, int);
-extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
-extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
- size_t, int);
+/**
+ * gen_pool_create() - create a new special memory pool
+ * @min_alloc_order: log base 2 of number of bytes each bitmap entry
+ * represents
+ * @nid: node id of the node the pool structure should be allocated on,
+ * or -1
+ *
+ * Create a new special memory pool that can be used to manage special
+ * purpose memory not managed by the regular kmalloc/kfree interface.
+ *
+ * Return:
+ * * pointer to the pool - success
+ * * NULL - otherwise
+ */
+struct gen_pool *gen_pool_create(int min_alloc_order, int nid);
+
+/**
+ * gen_pool_add_virt() - add a new chunk of special memory to the pool
+ * @pool: pool to add new memory chunk to
+ * @virt: virtual starting address of memory chunk to add to pool
+ * @phys: physical starting address of memory chunk to add to pool
+ * @size: size in bytes of the memory chunk to add to pool
+ * @nid: node id of the node the chunk structure and bitmap should be
+ * allocated on, or -1
+ *
+ * Add a new chunk of special memory to the specified pool.
+ *
+ * Return:
+ * * 0 - success
+ * * -ve errno - failure
+ */
+int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt,
+ phys_addr_t phys, size_t size, int nid);
+
/**
* gen_pool_add - add a new chunk of special memory to the pool
* @pool: pool to add new memory chunk to
@@ -107,60 +137,300 @@ extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
*
* Add a new chunk of special memory to the specified pool.
*
- * Returns 0 on success or a -ve errno on failure.
+ * Return:
+ * * 0 - on success
+ * *-ve errno - failure
*/
static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
size_t size, int nid)
{
return gen_pool_add_virt(pool, addr, -1, size, nid);
}
-extern void gen_pool_destroy(struct gen_pool *);
-extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
-extern unsigned long gen_pool_alloc_algo(struct gen_pool *, size_t,
- genpool_algo_t algo, void *data);
-extern void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size,
- dma_addr_t *dma);
-extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
-extern void gen_pool_for_each_chunk(struct gen_pool *,
- void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
-extern size_t gen_pool_avail(struct gen_pool *);
-extern size_t gen_pool_size(struct gen_pool *);
-extern void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo,
- void *data);
+/**
+ * gen_pool_virt_to_phys() - return the physical address of memory
+ * @pool: pool to allocate from
+ * @addr: starting address of memory
+ *
+ * Return:
+ * * the physical address - success
+ * * \-1 - error
+ */
+phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr);
+
+/**
+ * gen_pool_destroy() - destroy a special memory pool
+ * @pool: pool to destroy
+ *
+ * Destroy the specified special memory pool. Verifies that there are no
+ * outstanding allocations.
+ */
+void gen_pool_destroy(struct gen_pool *pool);
+
+/**
+ * gen_pool_alloc() - allocate special memory from the pool
+ * @pool: pool to allocate from
+ * @size: number of bytes to allocate from the pool
+ *
+ * Allocate the requested number of bytes from the specified pool.
+ * Uses the pool allocation function (with first-fit algorithm by default).
+ * Can not be used in NMI handler on architectures without
+ * NMI-safe cmpxchg implementation.
+ *
+ * Return:
+ * * address of the memory allocated - success
+ * * NULL - error
+ */
+unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size);
+
+/**
+ * gen_pool_alloc_algo() - allocate special memory from the pool
+ * @pool: pool to allocate from
+ * @size: number of bytes to allocate from the pool
+ * @algo: algorithm passed from caller
+ * @data: data passed to algorithm
+ *
+ * Allocate the requested number of bytes from the specified pool.
+ * Uses the pool allocation function (with first-fit algorithm by default).
+ * Can not be used in NMI handler on architectures without
+ * NMI-safe cmpxchg implementation.
+ *
+ * Return:
+ * * address of the memory allocated - success
+ * * NULL - error
+ */
+unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
+ genpool_algo_t algo, void *data);
+
+/**
+ * gen_pool_dma_alloc() - allocate special memory from the pool for DMA usage
+ * @pool: pool to allocate from
+ * @size: number of bytes to allocate from the pool
+ * @dma: dma-view physical address return value. Use NULL if unneeded.
+ *
+ * Allocate the requested number of bytes from the specified pool.
+ * Uses the pool allocation function (with first-fit algorithm by default).
+ * Can not be used in NMI handler on architectures without
+ * NMI-safe cmpxchg implementation.
+ *
+ * Return:
+ * * address of the memory allocated - success
+ * * NULL - error
+ */
+void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma);
+
+/**
+ * gen_pool_free() - free allocated special memory back to the pool
+ * @pool: pool to free to
+ * @addr: starting address of memory to free back to pool
+ * @size: size in bytes of memory to free or 0, for auto-detection
+ *
+ * Free previously allocated special memory back to the specified
+ * pool. Can not be used in NMI handler on architectures without
+ * NMI-safe cmpxchg implementation.
+ */
+void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size);
+
+/**
+ * gen_pool_for_each_chunk() - call func for every chunk of generic memory pool
+ * @pool: the generic memory pool
+ * @func: func to call
+ * @data: additional data used by @func
+ *
+ * Call @func for every chunk of generic memory pool. The @func is
+ * called with rcu_read_lock held.
+ */
+void gen_pool_for_each_chunk(struct gen_pool *pool,
+ void (*func)(struct gen_pool *pool,
+ struct gen_pool_chunk *chunk,
+ void *data),
+ void *data);
+
+/**
+ * addr_in_gen_pool() - checks if an address falls within the range of a pool
+ * @pool: the generic memory pool
+ * @start: start address
+ * @size: size of the region
+ *
+ * Check if the range of addresses falls within the specified pool.
+ *
+ * Return:
+ * * true - the entire range is contained in the pool
+ * * false - otherwise
+ */
+bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
+ size_t size);
+
+/**
+ * gen_pool_avail() - get available free space of the pool
+ * @pool: pool to get available free space
+ *
+ * Return: available free space of the specified pool.
+ */
+size_t gen_pool_avail(struct gen_pool *pool);
-extern unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
- unsigned long start, unsigned int nr, void *data,
- struct gen_pool *pool);
+/**
+ * gen_pool_size() - get size in bytes of memory managed by the pool
+ * @pool: pool to get size
+ *
+ * Return: size in bytes of memory managed by the pool.
+ */
+size_t gen_pool_size(struct gen_pool *pool);
-extern unsigned long gen_pool_fixed_alloc(unsigned long *map,
- unsigned long size, unsigned long start, unsigned int nr,
- void *data, struct gen_pool *pool);
+/**
+ * gen_pool_set_algo() - set the allocation algorithm
+ * @pool: pool to change allocation algorithm
+ * @algo: custom algorithm function
+ * @data: additional data used by @algo
+ *
+ * Call @algo for each memory allocation in the pool.
+ * If @algo is NULL use gen_pool_first_fit as default
+ * memory allocation function.
+ */
+void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data);
-extern unsigned long gen_pool_first_fit_align(unsigned long *map,
- unsigned long size, unsigned long start, unsigned int nr,
- void *data, struct gen_pool *pool);
+/**
+ * gen_pool_first_fit() - find the first available region
+ * of memory matching the size requirement (no alignment constraint)
+ * @map: The address to base the search on
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
+ * @data: additional data - unused
+ * @pool: pool to find the fit region memory from
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
+ */
+unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
+ unsigned long start, unsigned int nr,
+ void *data, struct gen_pool *pool);
+/**
+ * gen_pool_first_fit_align() - find the first available region
+ * of memory matching the size requirement (alignment constraint)
+ * @map: The address to base the search on
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
+ * @data: data for alignment
+ * @pool: pool to get order from
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
+ */
+unsigned long gen_pool_first_fit_align(unsigned long *map,
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr, void *data,
+ struct gen_pool *pool);
-extern unsigned long gen_pool_first_fit_order_align(unsigned long *map,
- unsigned long size, unsigned long start, unsigned int nr,
- void *data, struct gen_pool *pool);
+/**
+ * gen_pool_fixed_alloc() - reserve a specific region
+ * @map: The address to base the search on
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
+ * @data: data for alignment
+ * @pool: pool to get order from
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
+ */
+unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
+ unsigned long start, unsigned int nr,
+ void *data, struct gen_pool *pool);
-extern unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
- unsigned long start, unsigned int nr, void *data,
- struct gen_pool *pool);
+/**
+ * gen_pool_first_fit_order_align() - find the first available region
+ * of memory matching the size requirement. The region will be aligned
+ * to the order of the size specified.
+ * @map: The address to base the search on
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
+ * @data: additional data - unused
+ * @pool: pool to find the fit region memory from
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
+ */
+unsigned long gen_pool_first_fit_order_align(unsigned long *map,
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr, void *data,
+ struct gen_pool *pool);
+/**
+ * gen_pool_best_fit() - find the best fitting region of memory
+ * matching the size requirement (no alignment constraint)
+ * @map: The address to base the search on
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
+ * @data: additional data - unused
+ * @pool: pool to find the fit region memory from
+ *
+ * Iterate over the bitmap to find the smallest free region
+ * which we can allocate the memory.
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
+ */
+unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
+ unsigned long start, unsigned int nr,
+ void *data, struct gen_pool *pool);
-extern struct gen_pool *devm_gen_pool_create(struct device *dev,
- int min_alloc_order, int nid, const char *name);
-extern struct gen_pool *gen_pool_get(struct device *dev, const char *name);
+/**
+ * gen_pool_get() - Obtain the gen_pool (if any) for a device
+ * @dev: device to retrieve the gen_pool from
+ * @name: name of a gen_pool or NULL, identifies a particular gen_pool
+ * on device
+ *
+ * Return:
+ * * the gen_pool for the device - if it exists
+ * * NULL - no pool exists for the device
+ */
+struct gen_pool *gen_pool_get(struct device *dev, const char *name);
-bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
- size_t size);
+/**
+ * devm_gen_pool_create() - managed gen_pool_create
+ * @dev: device that provides the gen_pool
+ * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
+ * @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
+ * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
+ *
+ * Create a new special memory pool that can be used to manage special purpose
+ * memory not managed by the regular kmalloc/kfree interface. The pool will be
+ * automatically destroyed by the device management code.
+ *
+ * Return:
+ * * address of the pool - success
+ * * NULL - error
+ */
+struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
+ int nid, const char *name);
+/**
+ * of_gen_pool_get() - find a pool by phandle property
+ * @np: device node
+ * @propname: property name containing phandle(s)
+ * @index: index into the phandle array
+ *
+ * Return:
+ * * pool address - it contains the chunk starting at the physical
+ * address of the device tree node pointed at by
+ * the phandle property
+ * * NULL - otherwise
+ */
#ifdef CONFIG_OF
-extern struct gen_pool *of_gen_pool_get(struct device_node *np,
- const char *propname, int index);
+struct gen_pool *of_gen_pool_get(struct device_node *np,
+ const char *propname, int index);
#else
static inline struct gen_pool *of_gen_pool_get(struct device_node *np,
const char *propname, int index)
diff --git a/lib/genalloc.c b/lib/genalloc.c
index ca06adc4f445..d505b959f888 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -26,6 +26,74 @@
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
+ *
+ *
+ *
+ * Encoding of the bitmap tracking the allocations
+ * -----------------------------------------------
+ *
+ * The bitmap is composed of units of allocations.
+ *
+ * Each unit of allocation is represented using 2 consecutive bits.
+ *
+ * This makes it possible to encode, for each unit of allocation,
+ * information about:
+ * - allocation status (busy/free)
+ * - beginning of a sequennce of allocation units (first / successive)
+ *
+ *
+ * Dictionary of allocation units (msb to the left, lsb to the right):
+ *
+ * 11: first allocation unit in the allocation
+ * 10: any subsequent allocation unit (if any) in the allocation
+ * 00: available allocation unit
+ * 01: invalid
+ *
+ * Example, using the same notation as above - MSb.......LSb:
+ *
+ * ...000010111100000010101011 <-- Read in this direction.
+ * \__|\__|\|\____|\______|
+ * | | | | \___ 4 used allocation units
+ * | | | \___________ 3 empty allocation units
+ * | | \_________________ 1 used allocation unit
+ * | \___________________ 2 used allocation units
+ * \_______________________ 2 empty allocation units
+ *
+ * The encoding allows for lockless operations, such as:
+ * - search for a sufficiently large range of allocation units
+ * - reservation of a selected range of allocation units
+ * - release of a specific allocation
+ *
+ * The alignment at which to perform the research for sequence of empty
+ * allocation units (marked as zeros in the bitmap) is 2^1.
+ *
+ * This means that an allocation can start only at even places
+ * (bit 0, bit 2, etc.) in the bitmap.
+ *
+ * Therefore, the number of zeroes to look for must be twice the number
+ * of desired allocation units.
+ *
+ * When it's time to free the memory associated to an allocation request,
+ * it's a matter of checking if the corresponding allocation unit is
+ * really the beginning of an allocation (both bits are set to 1).
+ *
+ * Looking for the ending can also be performed locklessly.
+ * It's sufficient to identify the first mapped allocation unit
+ * that is represented either as free (00) or busy (11).
+ * Even if the allocation status should change in the meanwhile, it
+ * doesn't matter, since it can only transition between free (00) and
+ * first-allocated (11).
+ *
+ * The parameter indicating to the *_free() function the size of the
+ * space that should be freed can be either set to 0, for automated
+ * assessment, or it can be specified explicitly.
+ *
+ * In case it is specified explicitly, the value is verified agaisnt what
+ * the library is tracking internally.
+ *
+ * If ever needed, the bitmap could be extended, assigning larger amounts
+ * of bits to each allocation unit (the increase must follow powers of 2),
+ * to track other properties of the allocations.
*/
#include <linux/slab.h>
@@ -35,119 +103,251 @@
#include <linux/interrupt.h>
#include <linux/genalloc.h>
#include <linux/of_device.h>
+#include <linux/bug.h>
+
+#define ENTRY_ORDER 1UL
+#define ENTRY_MASK ((1UL << ((ENTRY_ORDER) + 1UL)) - 1UL)
+#define ENTRY_HEAD ENTRY_MASK
+#define ENTRY_UNUSED 0UL
+#define BITS_PER_ENTRY (1U << ENTRY_ORDER)
+#define BITS_DIV_ENTRIES(x) ((x) >> ENTRY_ORDER)
+#define ENTRIES_TO_BITS(x) ((x) << ENTRY_ORDER)
+#define BITS_DIV_LONGS(x) ((x) / BITS_PER_LONG)
+#define ENTRIES_DIV_LONGS(x) (BITS_DIV_LONGS(ENTRIES_TO_BITS(x)))
+
+#define ENTRIES_PER_LONG BITS_DIV_ENTRIES(BITS_PER_LONG)
+
+/* Binary pattern of 1010...1010 that spans one unsigned long. */
+#define MASK (~0UL / 3 * 2)
+
+/**
+ * get_bitmap_entry() - extracts the specified entry from the bitmap
+ * @map: pointer to a bitmap
+ * @entry_index: the index of the desired entry in the bitmap
+ *
+ * Return: The requested bitmap.
+ */
+static inline unsigned long get_bitmap_entry(unsigned long *map,
+ int entry_index)
+{
+ return (map[ENTRIES_DIV_LONGS(entry_index)] >>
+ ENTRIES_TO_BITS(entry_index % ENTRIES_PER_LONG)) &
+ ENTRY_MASK;
+}
+
+/**
+ * mem_to_units() - convert references to memory into orders of allocation
+ * @size: amount in bytes
+ * @order: power of 2 represented by each entry in the bitmap
+ *
+ * Return: the number of units representing the size.
+ */
+static inline unsigned long mem_to_units(unsigned long size,
+ unsigned long order)
+{
+ return (size + (1UL << order) - 1) >> order;
+}
+
+/**
+ * chunk_size() - dimension of a chunk of memory, in bytes
+ * @chunk: pointer to the struct describing the chunk
+ *
+ * Return: The size of the chunk, in bytes.
+ */
static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
{
return chunk->end_addr - chunk->start_addr + 1;
}
-static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
+
+/**
+ * set_bits_ll() - based on value and mask, sets bits at address
+ * @addr: where to write
+ * @mask: filter to apply for the bits to alter
+ * @value: actual configuration of bits to store
+ *
+ * Return:
+ * * 0 - success
+ * * -EBUSY - otherwise
+ */
+static int set_bits_ll(unsigned long *addr,
+ unsigned long mask, unsigned long value)
{
- unsigned long val, nval;
+ unsigned long nval;
+ unsigned long present;
+ unsigned long target;
nval = *addr;
do {
- val = nval;
- if (val & mask_to_set)
+ present = nval;
+ if (present & mask)
return -EBUSY;
+ target = present | value;
cpu_relax();
- } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
-
+ } while ((nval = cmpxchg(addr, present, target)) != target);
return 0;
}
-static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
+
+/**
+ * clear_bits_ll() - based on value and mask, clears bits at address
+ * @addr: where to write
+ * @mask: filter to apply for the bits to alter
+ * @value: actual configuration of bits to clear
+ *
+ * Return:
+ * * 0 - success
+ * * -EBUSY - otherwise
+ */
+static int clear_bits_ll(unsigned long *addr,
+ unsigned long mask, unsigned long value)
{
- unsigned long val, nval;
+ unsigned long nval;
+ unsigned long present;
+ unsigned long target;
nval = *addr;
+ present = nval;
+ if (unlikely((present & mask) ^ value))
+ return -EBUSY;
do {
- val = nval;
- if ((val & mask_to_clear) != mask_to_clear)
+ present = nval;
+ if (unlikely((present & mask) ^ value))
return -EBUSY;
+ target = present & ~mask;
cpu_relax();
- } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
-
+ } while ((nval = cmpxchg(addr, present, target)) != target);
return 0;
}
-/*
- * bitmap_set_ll - set the specified number of bits at the specified position
+
+/**
+ * get_boundary() - verifies address, then measure length.
* @map: pointer to a bitmap
- * @start: a bit position in @map
- * @nr: number of bits to set
+ * @start_entry: the index of the first entry in the bitmap
+ * @nentries: number of entries to alter
*
- * Set @nr bits start from @start in @map lock-lessly. Several users
- * can set/clear the same bitmap simultaneously without lock. If two
- * users set the same bit, one user will return remain bits, otherwise
- * return 0.
+ * Return:
+ * * length of an allocation - success
+ * * -EINVAL - invalid parameters
*/
-static int bitmap_set_ll(unsigned long *map, int start, int nr)
+static int get_boundary(unsigned long *map, unsigned int start_entry,
+ unsigned int nentries)
{
- unsigned long *p = map + BIT_WORD(start);
- const int size = start + nr;
- int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
- unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
-
- while (nr - bits_to_set >= 0) {
- if (set_bits_ll(p, mask_to_set))
- return nr;
- nr -= bits_to_set;
- bits_to_set = BITS_PER_LONG;
- mask_to_set = ~0UL;
- p++;
- }
- if (nr) {
- mask_to_set &= BITMAP_LAST_WORD_MASK(size);
- if (set_bits_ll(p, mask_to_set))
- return nr;
- }
+ int i;
+ unsigned long bitmap_entry;
- return 0;
+
+ if (unlikely(get_bitmap_entry(map, start_entry) != ENTRY_HEAD))
+ return -EINVAL;
+ for (i = start_entry + 1; i < nentries; i++) {
+ bitmap_entry = get_bitmap_entry(map, i);
+ if (bitmap_entry == ENTRY_HEAD ||
+ bitmap_entry == ENTRY_UNUSED)
+ return i;
+ }
+ return nentries - start_entry;
}
+
+#define SET_BITS 1
+#define CLEAR_BITS 0
+
/*
- * bitmap_clear_ll - clear the specified number of bits at the specified position
+ * alter_bitmap_ll() - set/clear the entries associated with an allocation
+ * @alteration: indicates if the bits selected should be set or cleared
* @map: pointer to a bitmap
- * @start: a bit position in @map
- * @nr: number of bits to set
+ * @start: the index of the first entry in the bitmap
+ * @nentries: number of entries to alter
*
- * Clear @nr bits start from @start in @map lock-lessly. Several users
- * can set/clear the same bitmap simultaneously without lock. If two
- * users clear the same bit, one user will return remain bits,
- * otherwise return 0.
+ * The modification happens lock-lessly.
+ * Several users can write to the same map simultaneously, without lock.
+ * In case of mid-air conflict, when 2 or more writers try to alter the
+ * same word in the bitmap, only one will succeed and continue, the others
+ * will fail and receive as return value the amount of entries that were
+ * not written. Each failed writer is responsible to revert the changes
+ * it did to the bitmap.
+ * The lockless conflict resolution is implemented through cmpxchg.
+ * Success or failure is purely based on first come first served basis.
+ * The first writer that manages to gain write access to the target word
+ * of the bitmap wins. Whatever can affect the order and priority of execution
+ * of the writers can and will affect the result of the race.
+ *
+ * Return:
+ * * 0 - success
+ * * remaining entries - failure
*/
-static int bitmap_clear_ll(unsigned long *map, int start, int nr)
+static unsigned int alter_bitmap_ll(bool alteration, unsigned long *map,
+ unsigned int start_entry,
+ unsigned int nentries)
{
- unsigned long *p = map + BIT_WORD(start);
- const int size = start + nr;
- int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
- unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
-
- while (nr - bits_to_clear >= 0) {
- if (clear_bits_ll(p, mask_to_clear))
- return nr;
- nr -= bits_to_clear;
- bits_to_clear = BITS_PER_LONG;
- mask_to_clear = ~0UL;
- p++;
- }
- if (nr) {
- mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
- if (clear_bits_ll(p, mask_to_clear))
- return nr;
+ unsigned long start_bit;
+ unsigned long end_bit;
+ unsigned long mask;
+ unsigned long value;
+ unsigned int nbits;
+ unsigned int bits_to_write;
+ unsigned int index;
+ int (*action)(unsigned long *addr,
+ unsigned long mask, unsigned long value);
+
+ action = (alteration == SET_BITS) ? set_bits_ll : clear_bits_ll;
+
+ /*
+ * Prepare for writing the initial part of the allocation, from
+ * starting entry, to the end of the UL bitmap element which
+ * contains it. It might be larger than the actual allocation.
+ */
+ start_bit = ENTRIES_TO_BITS(start_entry);
+ end_bit = ENTRIES_TO_BITS(start_entry + nentries);
+ nbits = ENTRIES_TO_BITS(nentries);
+ bits_to_write = BITS_PER_LONG - start_bit % BITS_PER_LONG;
+ mask = BITMAP_FIRST_WORD_MASK(start_bit);
+ /* Mark the beginning of the allocation. */
+ value = MASK | (1UL << (start_bit % BITS_PER_LONG));
+ index = BITS_DIV_LONGS(start_bit);
+
+ /*
+ * Writes entries to the bitmap, as long as the reminder is
+ * positive or zero.
+ * Might be skipped if the entries to write do not reach the end
+ * of a bitmap UL unit.
+ */
+ while (nbits >= bits_to_write) {
+ if (action(map + index, mask, value & mask))
+ return BITS_DIV_ENTRIES(nbits);
+ nbits -= bits_to_write;
+ bits_to_write = BITS_PER_LONG;
+ mask = ~0UL;
+ value = MASK;
+ index++;
}
+ /* Takes care of the ending part of the entries to mark. */
+ if (nbits > 0) {
+ mask ^= BITMAP_FIRST_WORD_MASK((end_bit) % BITS_PER_LONG);
+ bits_to_write = nbits;
+ if (action(map + index, mask, value & mask))
+ return BITS_DIV_ENTRIES(nbits);
+ }
return 0;
}
+
/**
- * gen_pool_create - create a new special memory pool
- * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
- * @nid: node id of the node the pool structure should be allocated on, or -1
+ * gen_pool_create() - create a new special memory pool
+ * @min_alloc_order: log base 2 of number of bytes each bitmap entry
+ * represents
+ * @nid: node id of the node the pool structure should be allocated on,
+ * or -1
*
- * Create a new special memory pool that can be used to manage special purpose
- * memory not managed by the regular kmalloc/kfree interface.
+ * Create a new special memory pool that can be used to manage special
+ * purpose memory not managed by the regular kmalloc/kfree interface.
+ *
+ * Return:
+ * * pointer to the pool - success
+ * * NULL - otherwise
*/
struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
{
@@ -167,7 +367,7 @@ struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
EXPORT_SYMBOL(gen_pool_create);
/**
- * gen_pool_add_virt - add a new chunk of special memory to the pool
+ * gen_pool_add_virt() - add a new chunk of special memory to the pool
* @pool: pool to add new memory chunk to
* @virt: virtual starting address of memory chunk to add to pool
* @phys: physical starting address of memory chunk to add to pool
@@ -177,16 +377,20 @@ EXPORT_SYMBOL(gen_pool_create);
*
* Add a new chunk of special memory to the specified pool.
*
- * Returns 0 on success or a -ve errno on failure.
+ * Return:
+ * * 0 - success
+ * * -ve errno - failure
*/
-int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
- size_t size, int nid)
+int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt,
+ phys_addr_t phys, size_t size, int nid)
{
struct gen_pool_chunk *chunk;
- int nbits = size >> pool->min_alloc_order;
- int nbytes = sizeof(struct gen_pool_chunk) +
- BITS_TO_LONGS(nbits) * sizeof(long);
+ unsigned int nentries;
+ unsigned int nbytes;
+ nentries = size >> pool->min_alloc_order;
+ nbytes = sizeof(struct gen_pool_chunk) +
+ ENTRIES_DIV_LONGS(nentries) * sizeof(long);
chunk = kzalloc_node(nbytes, GFP_KERNEL, nid);
if (unlikely(chunk == NULL))
return -ENOMEM;
@@ -205,11 +409,13 @@ int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phy
EXPORT_SYMBOL(gen_pool_add_virt);
/**
- * gen_pool_virt_to_phys - return the physical address of memory
+ * gen_pool_virt_to_phys() - return the physical address of memory
* @pool: pool to allocate from
* @addr: starting address of memory
*
- * Returns the physical address on success, or -1 on error.
+ * Return:
+ * * the physical address - success
+ * * \-1 - error
*/
phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
{
@@ -230,7 +436,7 @@ phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
EXPORT_SYMBOL(gen_pool_virt_to_phys);
/**
- * gen_pool_destroy - destroy a special memory pool
+ * gen_pool_destroy() - destroy a special memory pool
* @pool: pool to destroy
*
* Destroy the specified special memory pool. Verifies that there are no
@@ -240,26 +446,33 @@ void gen_pool_destroy(struct gen_pool *pool)
{
struct list_head *_chunk, *_next_chunk;
struct gen_pool_chunk *chunk;
- int order = pool->min_alloc_order;
- int bit, end_bit;
+ unsigned int order = pool->min_alloc_order;
+ unsigned long bit, end_bit;
+ bool empty = true;
list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
list_del(&chunk->next_chunk);
end_bit = chunk_size(chunk) >> order;
- bit = find_next_bit(chunk->bits, end_bit, 0);
- BUG_ON(bit < end_bit);
-
+ bit = find_next_bit(chunk->entries, end_bit, 0);
+ if (unlikely(bit < end_bit)) {
+ WARN(true, "Attempt to destroy non-empty pool %s",
+ pool->name);
+ empty = false;
+ continue;
+ }
kfree(chunk);
}
- kfree_const(pool->name);
- kfree(pool);
+ if (likely(empty)) {
+ kfree_const(pool->name);
+ kfree(pool);
+ }
}
EXPORT_SYMBOL(gen_pool_destroy);
/**
- * gen_pool_alloc - allocate special memory from the pool
+ * gen_pool_alloc() - allocate special memory from the pool
* @pool: pool to allocate from
* @size: number of bytes to allocate from the pool
*
@@ -267,6 +480,10 @@ EXPORT_SYMBOL(gen_pool_destroy);
* Uses the pool allocation function (with first-fit algorithm by default).
* Can not be used in NMI handler on architectures without
* NMI-safe cmpxchg implementation.
+ *
+ * Return:
+ * * address of the memory allocated - success
+ * * NULL - error
*/
unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
{
@@ -275,7 +492,7 @@ unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
EXPORT_SYMBOL(gen_pool_alloc);
/**
- * gen_pool_alloc_algo - allocate special memory from the pool
+ * gen_pool_alloc_algo() - allocate special memory from the pool
* @pool: pool to allocate from
* @size: number of bytes to allocate from the pool
* @algo: algorithm passed from caller
@@ -285,14 +502,18 @@ EXPORT_SYMBOL(gen_pool_alloc);
* Uses the pool allocation function (with first-fit algorithm by default).
* Can not be used in NMI handler on architectures without
* NMI-safe cmpxchg implementation.
+ *
+ * Return:
+ * * address of the memory allocated - success
+ * * NULL - error
*/
unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
genpool_algo_t algo, void *data)
{
struct gen_pool_chunk *chunk;
unsigned long addr = 0;
- int order = pool->min_alloc_order;
- int nbits, start_bit, end_bit, remain;
+ unsigned int order = pool->min_alloc_order;
+ unsigned int nentries, start_entry, end_entry, remain;
#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
BUG_ON(in_nmi());
@@ -301,29 +522,32 @@ unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
if (size == 0)
return 0;
- nbits = (size + (1UL << order) - 1) >> order;
+ nentries = mem_to_units(size, order);
rcu_read_lock();
list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
if (size > atomic_long_read(&chunk->avail))
continue;
- start_bit = 0;
- end_bit = chunk_size(chunk) >> order;
+ start_entry = 0;
+ end_entry = chunk_size(chunk) >> order;
retry:
- start_bit = algo(chunk->bits, end_bit, start_bit,
- nbits, data, pool);
- if (start_bit >= end_bit)
+ start_entry = algo(chunk->entries, end_entry, start_entry,
+ nentries, data, pool);
+ if (start_entry >= end_entry)
continue;
- remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
+ remain = alter_bitmap_ll(SET_BITS, chunk->entries,
+ start_entry, nentries);
if (remain) {
- remain = bitmap_clear_ll(chunk->bits, start_bit,
- nbits - remain);
- BUG_ON(remain);
+ remain = alter_bitmap_ll(CLEAR_BITS,
+ chunk->entries,
+ start_entry,
+ nentries - remain);
goto retry;
}
- addr = chunk->start_addr + ((unsigned long)start_bit << order);
- size = nbits << order;
+ addr = chunk->start_addr +
+ ((unsigned long)start_entry << order);
+ size = nentries << order;
atomic_long_sub(size, &chunk->avail);
break;
}
@@ -333,7 +557,7 @@ unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
EXPORT_SYMBOL(gen_pool_alloc_algo);
/**
- * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
+ * gen_pool_dma_alloc() - allocate special memory from the pool for DMA usage
* @pool: pool to allocate from
* @size: number of bytes to allocate from the pool
* @dma: dma-view physical address return value. Use NULL if unneeded.
@@ -342,14 +566,15 @@ EXPORT_SYMBOL(gen_pool_alloc_algo);
* Uses the pool allocation function (with first-fit algorithm by default).
* Can not be used in NMI handler on architectures without
* NMI-safe cmpxchg implementation.
+ *
+ * Return:
+ * * address of the memory allocated - success
+ * * NULL - error
*/
void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
{
unsigned long vaddr;
- if (!pool)
- return NULL;
-
vaddr = gen_pool_alloc(pool, size);
if (!vaddr)
return NULL;
@@ -362,10 +587,10 @@ void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
EXPORT_SYMBOL(gen_pool_dma_alloc);
/**
- * gen_pool_free - free allocated special memory back to the pool
+ * gen_pool_free() - free allocated special memory back to the pool
* @pool: pool to free to
* @addr: starting address of memory to free back to pool
- * @size: size in bytes of memory to free
+ * @size: size in bytes of memory to free or 0, for auto-detection
*
* Free previously allocated special memory back to the specified
* pool. Can not be used in NMI handler on architectures without
@@ -374,34 +599,63 @@ EXPORT_SYMBOL(gen_pool_dma_alloc);
void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
{
struct gen_pool_chunk *chunk;
- int order = pool->min_alloc_order;
- int start_bit, nbits, remain;
+ unsigned int order = pool->min_alloc_order;
+ unsigned int start_entry, remaining_entries, nentries, remain;
+ int boundary;
#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
BUG_ON(in_nmi());
#endif
- nbits = (size + (1UL << order) - 1) >> order;
rcu_read_lock();
list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
- BUG_ON(addr + size - 1 > chunk->end_addr);
- start_bit = (addr - chunk->start_addr) >> order;
- remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
- BUG_ON(remain);
- size = nbits << order;
- atomic_long_add(size, &chunk->avail);
+ if (unlikely(addr + size - 1 > chunk->end_addr)) {
+ rcu_read_unlock();
+ WARN(true,
+ "Trying to free unallocated memory"
+ " from pool %s", pool);
+ return;
+ }
+ start_entry = (addr - chunk->start_addr) >> order;
+ remaining_entries = (chunk->end_addr - addr) >> order;
+ boundary = get_boundary(chunk->entries, start_entry,
+ remaining_entries);
+ if (unlikely(exit_test(boundary < 0))) {
+ rcu_read_unlock();
+ WARN(true, "Corrupted pool %s", pool);
+ return;
+ }
+ nentries = boundary - start_entry;
+ if (unlikely(size && (nentries !=
+ mem_to_units(size, order)))) {
+ rcu_read_unlock();
+ WARN(true,
+ "Size provided differs from size "
+ "measured from pool %s", pool);
+ return;
+ }
+ remain = alter_bitmap_ll(CLEAR_BITS, chunk->entries,
+ start_entry, nentries);
+ if (unlikely(remain)) {
+ rcu_read_unlock();
+ WARN(true,
+ "Unexpected bitmap collision while"
+ " freeing memory in pool %s", pool);
+ return;
+ }
+ atomic_long_add(nentries << order, &chunk->avail);
rcu_read_unlock();
return;
}
}
rcu_read_unlock();
- BUG();
+ WARN(true, "address not found in pool %s", pool->name);
}
EXPORT_SYMBOL(gen_pool_free);
/**
- * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
+ * gen_pool_for_each_chunk() - call func for every chunk of generic memory pool
* @pool: the generic memory pool
* @func: func to call
* @data: additional data used by @func
@@ -423,16 +677,19 @@ void gen_pool_for_each_chunk(struct gen_pool *pool,
EXPORT_SYMBOL(gen_pool_for_each_chunk);
/**
- * addr_in_gen_pool - checks if an address falls within the range of a pool
+ * addr_in_gen_pool() - checks if an address falls within the range of a pool
* @pool: the generic memory pool
* @start: start address
* @size: size of the region
*
- * Check if the range of addresses falls within the specified pool. Returns
- * true if the entire range is contained in the pool and false otherwise.
+ * Check if the range of addresses falls within the specified pool.
+ *
+ * Return:
+ * * true - the entire range is contained in the pool
+ * * false - otherwise
*/
bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
- size_t size)
+ size_t size)
{
bool found = false;
unsigned long end = start + size - 1;
@@ -452,10 +709,10 @@ bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
}
/**
- * gen_pool_avail - get available free space of the pool
+ * gen_pool_avail() - get available free space of the pool
* @pool: pool to get available free space
*
- * Return available free space of the specified pool.
+ * Return: available free space of the specified pool.
*/
size_t gen_pool_avail(struct gen_pool *pool)
{
@@ -471,10 +728,10 @@ size_t gen_pool_avail(struct gen_pool *pool)
EXPORT_SYMBOL_GPL(gen_pool_avail);
/**
- * gen_pool_size - get size in bytes of memory managed by the pool
+ * gen_pool_size() - get size in bytes of memory managed by the pool
* @pool: pool to get size
*
- * Return size in bytes of memory managed by the pool.
+ * Return: size in bytes of memory managed by the pool.
*/
size_t gen_pool_size(struct gen_pool *pool)
{
@@ -490,7 +747,7 @@ size_t gen_pool_size(struct gen_pool *pool)
EXPORT_SYMBOL_GPL(gen_pool_size);
/**
- * gen_pool_set_algo - set the allocation algorithm
+ * gen_pool_set_algo() - set the allocation algorithm
* @pool: pool to change allocation algorithm
* @algo: custom algorithm function
* @data: additional data used by @algo
@@ -514,137 +771,200 @@ void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
EXPORT_SYMBOL(gen_pool_set_algo);
/**
- * gen_pool_first_fit - find the first available region
+ * gen_pool_first_fit() - find the first available region
* of memory matching the size requirement (no alignment constraint)
* @map: The address to base the search on
- * @size: The bitmap size in bits
- * @start: The bitnumber to start searching at
- * @nr: The number of zeroed bits we're looking for
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
* @data: additional data - unused
* @pool: pool to find the fit region memory from
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
*/
unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
- unsigned long start, unsigned int nr, void *data,
- struct gen_pool *pool)
+ unsigned long start, unsigned int nr,
+ void *data, struct gen_pool *pool)
{
- return bitmap_find_next_zero_area(map, size, start, nr, 0);
+ unsigned long align_mask;
+ unsigned long bit_index;
+
+ align_mask = roundup_pow_of_two(BITS_PER_ENTRY) - 1;
+ bit_index = bitmap_find_next_zero_area(map, ENTRIES_TO_BITS(size),
+ ENTRIES_TO_BITS(start),
+ ENTRIES_TO_BITS(nr),
+ align_mask);
+ return BITS_DIV_ENTRIES(bit_index);
}
EXPORT_SYMBOL(gen_pool_first_fit);
/**
- * gen_pool_first_fit_align - find the first available region
+ * gen_pool_first_fit_align() - find the first available region
* of memory matching the size requirement (alignment constraint)
* @map: The address to base the search on
- * @size: The bitmap size in bits
- * @start: The bitnumber to start searching at
- * @nr: The number of zeroed bits we're looking for
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
* @data: data for alignment
* @pool: pool to get order from
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
*/
-unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
- unsigned long start, unsigned int nr, void *data,
- struct gen_pool *pool)
+unsigned long gen_pool_first_fit_align(unsigned long *map,
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr, void *data,
+ struct gen_pool *pool)
{
struct genpool_data_align *alignment;
unsigned long align_mask;
- int order;
+ unsigned long bit_index;
+ unsigned int order;
alignment = data;
order = pool->min_alloc_order;
- align_mask = ((alignment->align + (1UL << order) - 1) >> order) - 1;
- return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
+ align_mask = roundup_pow_of_two(
+ ENTRIES_TO_BITS(mem_to_units(alignment->align,
+ order))) - 1;
+ bit_index = bitmap_find_next_zero_area(map, ENTRIES_TO_BITS(size),
+ ENTRIES_TO_BITS(start),
+ ENTRIES_TO_BITS(nr),
+ align_mask);
+ return BITS_DIV_ENTRIES(bit_index);
}
EXPORT_SYMBOL(gen_pool_first_fit_align);
/**
- * gen_pool_fixed_alloc - reserve a specific region
+ * gen_pool_fixed_alloc() - reserve a specific region
* @map: The address to base the search on
- * @size: The bitmap size in bits
- * @start: The bitnumber to start searching at
- * @nr: The number of zeroed bits we're looking for
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
* @data: data for alignment
* @pool: pool to get order from
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
*/
unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
- unsigned long start, unsigned int nr, void *data,
- struct gen_pool *pool)
+ unsigned long start, unsigned int nr,
+ void *data, struct gen_pool *pool)
{
struct genpool_data_fixed *fixed_data;
- int order;
- unsigned long offset_bit;
- unsigned long start_bit;
+ unsigned int order;
+ unsigned long offset;
+ unsigned long align_mask;
+ unsigned long bit_index;
fixed_data = data;
order = pool->min_alloc_order;
- offset_bit = fixed_data->offset >> order;
if (WARN_ON(fixed_data->offset & ((1UL << order) - 1)))
return size;
+ offset = fixed_data->offset >> order;
+ align_mask = roundup_pow_of_two(BITS_PER_ENTRY) - 1;
+ bit_index = bitmap_find_next_zero_area(map, ENTRIES_TO_BITS(size),
+ ENTRIES_TO_BITS(start + offset),
+ ENTRIES_TO_BITS(nr), align_mask);
+ if (bit_index != ENTRIES_TO_BITS(offset))
+ return size;
- start_bit = bitmap_find_next_zero_area(map, size,
- start + offset_bit, nr, 0);
- if (start_bit != offset_bit)
- start_bit = size;
- return start_bit;
+ return BITS_DIV_ENTRIES(bit_index);
}
EXPORT_SYMBOL(gen_pool_fixed_alloc);
/**
- * gen_pool_first_fit_order_align - find the first available region
+ * gen_pool_first_fit_order_align() - find the first available region
* of memory matching the size requirement. The region will be aligned
* to the order of the size specified.
* @map: The address to base the search on
- * @size: The bitmap size in bits
- * @start: The bitnumber to start searching at
- * @nr: The number of zeroed bits we're looking for
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
* @data: additional data - unused
* @pool: pool to find the fit region memory from
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
*/
unsigned long gen_pool_first_fit_order_align(unsigned long *map,
- unsigned long size, unsigned long start,
- unsigned int nr, void *data, struct gen_pool *pool)
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr, void *data,
+ struct gen_pool *pool)
{
- unsigned long align_mask = roundup_pow_of_two(nr) - 1;
-
- return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
+ unsigned long align_mask;
+ unsigned long bit_index;
+
+ align_mask = roundup_pow_of_two(ENTRIES_TO_BITS(nr)) - 1;
+ bit_index = bitmap_find_next_zero_area(map, ENTRIES_TO_BITS(size),
+ ENTRIES_TO_BITS(start),
+ ENTRIES_TO_BITS(nr),
+ align_mask);
+ return BITS_DIV_ENTRIES(bit_index);
}
EXPORT_SYMBOL(gen_pool_first_fit_order_align);
/**
- * gen_pool_best_fit - find the best fitting region of memory
- * macthing the size requirement (no alignment constraint)
+ * gen_pool_best_fit() - find the best fitting region of memory
+ * matching the size requirement (no alignment constraint)
* @map: The address to base the search on
- * @size: The bitmap size in bits
- * @start: The bitnumber to start searching at
- * @nr: The number of zeroed bits we're looking for
+ * @size: The number of allocation units in the bitmap
+ * @start: The allocation unit to start searching at
+ * @nr: The number of allocation units we're looking for
* @data: additional data - unused
* @pool: pool to find the fit region memory from
*
* Iterate over the bitmap to find the smallest free region
* which we can allocate the memory.
+ *
+ * Return:
+ * * index of the memory allocated - sufficient space available
+ * * end of the range - insufficient space
*/
unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
- unsigned long start, unsigned int nr, void *data,
- struct gen_pool *pool)
+ unsigned long start, unsigned int nr,
+ void *data, struct gen_pool *pool)
{
- unsigned long start_bit = size;
+ unsigned long start_bit = ENTRIES_TO_BITS(size);
unsigned long len = size + 1;
unsigned long index;
+ unsigned long align_mask;
+ unsigned long bit_index;
- index = bitmap_find_next_zero_area(map, size, start, nr, 0);
+ align_mask = roundup_pow_of_two(BITS_PER_ENTRY) - 1;
+ bit_index = bitmap_find_next_zero_area(map, ENTRIES_TO_BITS(size),
+ ENTRIES_TO_BITS(start),
+ ENTRIES_TO_BITS(nr),
+ align_mask);
+ index = BITS_DIV_ENTRIES(bit_index);
while (index < size) {
- int next_bit = find_next_bit(map, size, index + nr);
- if ((next_bit - index) < len) {
- len = next_bit - index;
- start_bit = index;
+ unsigned long next_bit;
+
+ next_bit = find_next_bit(map, ENTRIES_TO_BITS(size),
+ ENTRIES_TO_BITS(index + nr));
+ if ((BITS_DIV_ENTRIES(next_bit) - index) < len) {
+ len = BITS_DIV_ENTRIES(next_bit) - index;
+ start_bit = ENTRIES_TO_BITS(index);
if (len == nr)
- return start_bit;
+ return BITS_DIV_ENTRIES(start_bit);
}
- index = bitmap_find_next_zero_area(map, size,
- next_bit + 1, nr, 0);
+ bit_index =
+ bitmap_find_next_zero_area(map,
+ ENTRIES_TO_BITS(size),
+ next_bit + 1,
+ ENTRIES_TO_BITS(nr),
+ align_mask);
+ index = BITS_DIV_ENTRIES(bit_index);
}
- return start_bit;
+ return BITS_DIV_ENTRIES(start_bit);
}
EXPORT_SYMBOL(gen_pool_best_fit);
@@ -668,11 +988,14 @@ static int devm_gen_pool_match(struct device *dev, void *res, void *data)
}
/**
- * gen_pool_get - Obtain the gen_pool (if any) for a device
+ * gen_pool_get() - Obtain the gen_pool (if any) for a device
* @dev: device to retrieve the gen_pool from
- * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
+ * @name: name of a gen_pool or NULL, identifies a particular gen_pool
+ * on device
*
- * Returns the gen_pool for the device if one is present, or NULL.
+ * Return:
+ * * the gen_pool for the device - if it exists
+ * * NULL - no pool exists for the device
*/
struct gen_pool *gen_pool_get(struct device *dev, const char *name)
{
@@ -687,7 +1010,7 @@ struct gen_pool *gen_pool_get(struct device *dev, const char *name)
EXPORT_SYMBOL_GPL(gen_pool_get);
/**
- * devm_gen_pool_create - managed gen_pool_create
+ * devm_gen_pool_create() - managed gen_pool_create
* @dev: device that provides the gen_pool
* @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
* @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
@@ -696,6 +1019,10 @@ EXPORT_SYMBOL_GPL(gen_pool_get);
* Create a new special memory pool that can be used to manage special purpose
* memory not managed by the regular kmalloc/kfree interface. The pool will be
* automatically destroyed by the device management code.
+ *
+ * Return:
+ * * address of the pool - success
+ * * NULL - error
*/
struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
int nid, const char *name)
@@ -738,17 +1065,19 @@ EXPORT_SYMBOL(devm_gen_pool_create);
#ifdef CONFIG_OF
/**
- * of_gen_pool_get - find a pool by phandle property
+ * of_gen_pool_get() - find a pool by phandle property
* @np: device node
* @propname: property name containing phandle(s)
* @index: index into the phandle array
*
- * Returns the pool that contains the chunk starting at the physical
- * address of the device tree node pointed at by the phandle property,
- * or NULL if not found.
+ * Return:
+ * * pool address - it contains the chunk starting at the physical
+ * address of the device tree node pointed at by
+ * the phandle property
+ * * NULL - otherwise
*/
struct gen_pool *of_gen_pool_get(struct device_node *np,
- const char *propname, int index)
+ const char *propname, int index)
{
struct platform_device *pdev;
struct device_node *np_pool, *parent;
--
2.14.1
Introduce a set of macros for writing concise test cases for genalloc.
The test cases are meant to provide regression testing, when working on
new functionality for genalloc.
Primarily they are meant to confirm that the various allocation strategy
will continue to work as expected.
The execution of the self testing is controlled through a Kconfig option.
The testing takes place in the very early stages of main.c, to ensure
that failures in genalloc are caught before they can cause unexplained
erratic behavior in any of genalloc users.
Therefore, it would not be advisable to implement it as module.
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/test_genalloc.h | 26 +++
init/main.c | 2 +
lib/Kconfig | 15 ++
lib/Makefile | 1 +
lib/test_genalloc.c | 410 ++++++++++++++++++++++++++++++++++++++++++
5 files changed, 454 insertions(+)
create mode 100644 include/linux/test_genalloc.h
create mode 100644 lib/test_genalloc.c
diff --git a/include/linux/test_genalloc.h b/include/linux/test_genalloc.h
new file mode 100644
index 000000000000..cc45c6c859cf
--- /dev/null
+++ b/include/linux/test_genalloc.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * test_genalloc.h
+ *
+ * (C) Copyright 2017 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+
+#ifndef __LINUX_TEST_GENALLOC_H
+#define __LINUX_TEST_GENALLOC_H
+
+
+#ifdef CONFIG_TEST_GENERIC_ALLOCATOR
+
+#include <linux/genalloc.h>
+
+void test_genalloc(void);
+
+#else
+
+static inline void test_genalloc(void){};
+
+#endif
+
+#endif
diff --git a/init/main.c b/init/main.c
index 969eaf140ef0..2bf1312fd2fe 100644
--- a/init/main.c
+++ b/init/main.c
@@ -90,6 +90,7 @@
#include <linux/cache.h>
#include <linux/rodata_test.h>
#include <linux/jump_label.h>
+#include <linux/test_genalloc.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -661,6 +662,7 @@ asmlinkage __visible void __init start_kernel(void)
*/
mem_encrypt_init();
+ test_genalloc();
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
diff --git a/lib/Kconfig b/lib/Kconfig
index e96089499371..361514324d64 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -287,6 +287,21 @@ config DECOMPRESS_LZ4
config GENERIC_ALLOCATOR
bool
+config TEST_GENERIC_ALLOCATOR
+ bool "genalloc tester"
+ default n
+ select GENERIC_ALLOCATOR
+ help
+ Enable automated testing of the generic allocator.
+ The testing is primarily for the tracking of allocated space.
+
+config TEST_GENERIC_ALLOCATOR_VERBOSE
+ bool "make the genalloc tester more verbose"
+ default n
+ select TEST_GENERIC_ALLOCATOR
+ help
+ More information will be displayed during the self-testing.
+
#
# reed solomon support is select'ed if needed
#
diff --git a/lib/Makefile b/lib/Makefile
index a90d4fcd748f..5b5ee8d8f6d6 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -108,6 +108,7 @@ obj-$(CONFIG_LIBCRC32C) += libcrc32c.o
obj-$(CONFIG_CRC8) += crc8.o
obj-$(CONFIG_XXHASH) += xxhash.o
obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o
+obj-$(CONFIG_TEST_GENERIC_ALLOCATOR) += test_genalloc.o
obj-$(CONFIG_842_COMPRESS) += 842/
obj-$(CONFIG_842_DECOMPRESS) += 842/
diff --git a/lib/test_genalloc.c b/lib/test_genalloc.c
new file mode 100644
index 000000000000..12a61c9e7558
--- /dev/null
+++ b/lib/test_genalloc.c
@@ -0,0 +1,410 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * test_genalloc.c
+ *
+ * (C) Copyright 2017 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/init.h>
+#include <linux/vmalloc.h>
+#include <linux/string.h>
+#include <linux/debugfs.h>
+#include <linux/atomic.h>
+#include <linux/genalloc.h>
+
+#include <linux/test_genalloc.h>
+
+
+/*
+ * In case of failure of any of these tests, memory corruption is almost
+ * guarranteed; allowing the boot to continue means risking to corrupt
+ * also any filesystem/block device accessed write mode.
+ * Therefore, BUG_ON() is used, when testing.
+ */
+
+
+/*
+ * Keep the bitmap small, while including case of cross-ulong mapping.
+ * For simplicity, the test cases use only 1 chunk of memory.
+ */
+#define BITMAP_SIZE_C 16
+#define ALLOC_ORDER 0
+
+#define ULONG_SIZE (sizeof(unsigned long))
+#define BITMAP_SIZE_UL (BITMAP_SIZE_C / ULONG_SIZE)
+#define MIN_ALLOC_SIZE (1 << ALLOC_ORDER)
+#define ENTRIES (BITMAP_SIZE_C * 8)
+#define CHUNK_SIZE (MIN_ALLOC_SIZE * ENTRIES)
+
+#ifndef CONFIG_TEST_GENERIC_ALLOCATOR_VERBOSE
+
+static inline void print_first_chunk_bitmap(struct gen_pool *pool) {}
+
+#else
+
+static void print_first_chunk_bitmap(struct gen_pool *pool)
+{
+ struct gen_pool_chunk *chunk;
+ char bitmap[BITMAP_SIZE_C * 2 + 1];
+ unsigned long i;
+ char *bm = bitmap;
+ char *entry;
+
+ if (unlikely(pool == NULL || pool->chunks.next == NULL))
+ return;
+
+ chunk = container_of(pool->chunks.next, struct gen_pool_chunk,
+ next_chunk);
+ entry = (void *)chunk->entries;
+ for (i = 1; i <= BITMAP_SIZE_C; i++)
+ bm += snprintf(bm, 3, "%02hhx", entry[BITMAP_SIZE_C - i]);
+ *bm = '\0';
+ pr_notice("chunk: %p bitmap: 0x%s\n", chunk, bitmap);
+
+}
+
+#endif
+
+enum test_commands {
+ CMD_ALLOCATOR,
+ CMD_ALLOCATE,
+ CMD_FLUSH,
+ CMD_FREE,
+ CMD_NUMBER,
+ CMD_END = CMD_NUMBER,
+};
+
+struct null_struct {
+ void *null;
+};
+
+struct test_allocator {
+ genpool_algo_t algo;
+ union {
+ struct genpool_data_align align;
+ struct genpool_data_fixed offset;
+ struct null_struct null;
+ } data;
+};
+
+struct test_action {
+ unsigned int location;
+ char pattern[BITMAP_SIZE_C];
+ unsigned int size;
+};
+
+
+struct test_command {
+ enum test_commands command;
+ union {
+ struct test_allocator allocator;
+ struct test_action action;
+ };
+};
+
+
+/*
+ * To pass an array literal as parameter to a macro, it must go through
+ * this one, first.
+ */
+#define ARR(...) __VA_ARGS__
+
+#define SET_DATA(parameter, value) \
+ .parameter = { \
+ .parameter = value, \
+ } \
+
+#define SET_ALLOCATOR(alloc, parameter, value) \
+{ \
+ .command = CMD_ALLOCATOR, \
+ .allocator = { \
+ .algo = (alloc), \
+ .data = { \
+ SET_DATA(parameter, value), \
+ }, \
+ } \
+}
+
+#define ACTION_MEM(act, mem_size, mem_loc, match) \
+{ \
+ .command = act, \
+ .action = { \
+ .size = (mem_size), \
+ .location = (mem_loc), \
+ .pattern = match, \
+ }, \
+}
+
+#define ALLOCATE_MEM(mem_size, mem_loc, match) \
+ ACTION_MEM(CMD_ALLOCATE, mem_size, mem_loc, ARR(match))
+
+#define FREE_MEM(mem_size, mem_loc, match) \
+ ACTION_MEM(CMD_FREE, mem_size, mem_loc, ARR(match))
+
+#define FLUSH_MEM() \
+{ \
+ .command = CMD_FLUSH, \
+}
+
+#define END() \
+{ \
+ .command = CMD_END, \
+}
+
+static inline int compare_bitmaps(const struct gen_pool *pool,
+ const char *reference)
+{
+ struct gen_pool_chunk *chunk;
+ char *bitmap;
+ unsigned int i;
+
+ chunk = container_of(pool->chunks.next, struct gen_pool_chunk,
+ next_chunk);
+ bitmap = (char *)chunk->entries;
+
+ for (i = 0; i < BITMAP_SIZE_C; i++)
+ if (bitmap[i] != reference[i])
+ return -1;
+ return 0;
+}
+
+static void callback_set_allocator(struct gen_pool *pool,
+ const struct test_command *cmd,
+ unsigned long *locations)
+{
+ gen_pool_set_algo(pool, cmd->allocator.algo,
+ (void *)&cmd->allocator.data);
+}
+
+static void callback_allocate(struct gen_pool *pool,
+ const struct test_command *cmd,
+ unsigned long *locations)
+{
+ const struct test_action *action = &cmd->action;
+
+ locations[action->location] = gen_pool_alloc(pool, action->size);
+ BUG_ON(!locations[action->location]);
+ print_first_chunk_bitmap(pool);
+ BUG_ON(compare_bitmaps(pool, action->pattern));
+}
+
+static void callback_flush(struct gen_pool *pool,
+ const struct test_command *cmd,
+ unsigned long *locations)
+{
+ unsigned int i;
+
+ for (i = 0; i < ENTRIES; i++)
+ if (locations[i]) {
+ gen_pool_free(pool, locations[i], 0);
+ locations[i] = 0;
+ }
+}
+
+static void callback_free(struct gen_pool *pool,
+ const struct test_command *cmd,
+ unsigned long *locations)
+{
+ const struct test_action *action = &cmd->action;
+
+ gen_pool_free(pool, locations[action->location], 0);
+ locations[action->location] = 0;
+ print_first_chunk_bitmap(pool);
+ BUG_ON(compare_bitmaps(pool, action->pattern));
+}
+
+static void (* const callbacks[CMD_NUMBER])(struct gen_pool *,
+ const struct test_command *,
+ unsigned long *) = {
+ [CMD_ALLOCATOR] = callback_set_allocator,
+ [CMD_ALLOCATE] = callback_allocate,
+ [CMD_FREE] = callback_free,
+ [CMD_FLUSH] = callback_flush,
+};
+
+static const struct test_command test_first_fit[] = {
+ SET_ALLOCATOR(gen_pool_first_fit, null, NULL),
+ ALLOCATE_MEM(3, 0, ARR({0x2b})),
+ ALLOCATE_MEM(2, 1, ARR({0xeb, 0x02})),
+ ALLOCATE_MEM(5, 2, ARR({0xeb, 0xae, 0x0a})),
+ FREE_MEM(2, 1, ARR({0x2b, 0xac, 0x0a})),
+ ALLOCATE_MEM(1, 1, ARR({0xeb, 0xac, 0x0a})),
+ FREE_MEM(0, 2, ARR({0xeb})),
+ FREE_MEM(0, 0, ARR({0xc0})),
+ FREE_MEM(0, 1, ARR({0x00})),
+ END(),
+};
+
+/*
+ * To make the test work for both 32bit and 64bit ulong sizes,
+ * allocate (8 / 2 * 4 - 1) = 15 bytes bytes, then 16, then 2.
+ * The first allocation prepares for the crossing of the 32bit ulong
+ * threshold. The following crosses the 32bit threshold and prepares for
+ * crossing the 64bit thresholds. The last is large enough (2 bytes) to
+ * cross the 64bit threshold.
+ * Then free the allocations in the order: 2nd, 1st, 3rd.
+ */
+static const struct test_command test_ulong_span[] = {
+ SET_ALLOCATOR(gen_pool_first_fit, null, NULL),
+ ALLOCATE_MEM(15, 0, ARR({0xab, 0xaa, 0xaa, 0x2a})),
+ ALLOCATE_MEM(16, 1, ARR({0xab, 0xaa, 0xaa, 0xea,
+ 0xaa, 0xaa, 0xaa, 0x2a})),
+ ALLOCATE_MEM(2, 2, ARR({0xab, 0xaa, 0xaa, 0xea,
+ 0xaa, 0xaa, 0xaa, 0xea,
+ 0x02})),
+ FREE_MEM(0, 1, ARR({0xab, 0xaa, 0xaa, 0x2a,
+ 0x00, 0x00, 0x00, 0xc0,
+ 0x02})),
+ FREE_MEM(0, 0, ARR({0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0xc0,
+ 0x02})),
+ FREE_MEM(0, 2, ARR({0x00})),
+ END(),
+};
+
+/*
+ * Create progressively smaller allocations A B C D E.
+ * then free B and D.
+ * Then create new allocation that would fit in both of the gaps left by
+ * B and D. Verify that it uses the gap from B.
+ */
+static const struct test_command test_first_fit_gaps[] = {
+ SET_ALLOCATOR(gen_pool_first_fit, null, NULL),
+ ALLOCATE_MEM(10, 0, ARR({0xab, 0xaa, 0x0a})),
+ ALLOCATE_MEM(8, 1, ARR({0xab, 0xaa, 0xba, 0xaa,
+ 0x0a})),
+ ALLOCATE_MEM(6, 2, ARR({0xab, 0xaa, 0xba, 0xaa,
+ 0xba, 0xaa})),
+ ALLOCATE_MEM(4, 3, ARR({0xab, 0xaa, 0xba, 0xaa,
+ 0xba, 0xaa, 0xab})),
+ ALLOCATE_MEM(2, 4, ARR({0xab, 0xaa, 0xba, 0xaa,
+ 0xba, 0xaa, 0xab, 0x0b})),
+ FREE_MEM(0, 1, ARR({0xab, 0xaa, 0x0a, 0x00,
+ 0xb0, 0xaa, 0xab, 0x0b})),
+ FREE_MEM(0, 3, ARR({0xab, 0xaa, 0x0a, 0x00,
+ 0xb0, 0xaa, 0x00, 0x0b})),
+ ALLOCATE_MEM(3, 3, ARR({0xab, 0xaa, 0xba, 0x02,
+ 0xb0, 0xaa, 0x00, 0x0b})),
+ FLUSH_MEM(),
+ END(),
+};
+
+/* Test first fit align */
+static const struct test_command test_first_fit_align[] = {
+ SET_ALLOCATOR(gen_pool_first_fit_align, align, 4),
+ ALLOCATE_MEM(5, 0, ARR({0xab, 0x02})),
+ ALLOCATE_MEM(3, 1, ARR({0xab, 0x02, 0x2b})),
+ ALLOCATE_MEM(2, 2, ARR({0xab, 0x02, 0x2b, 0x0b})),
+ ALLOCATE_MEM(1, 3, ARR({0xab, 0x02, 0x2b, 0x0b, 0x03})),
+ FREE_MEM(0, 0, ARR({0x00, 0x00, 0x2b, 0x0b, 0x03})),
+ FREE_MEM(0, 2, ARR({0x00, 0x00, 0x2b, 0x00, 0x03})),
+ ALLOCATE_MEM(2, 0, ARR({0x0b, 0x00, 0x2b, 0x00, 0x03})),
+ FLUSH_MEM(),
+ END(),
+};
+
+
+/* Test fixed alloc */
+static const struct test_command test_fixed_data[] = {
+ SET_ALLOCATOR(gen_pool_fixed_alloc, offset, 1),
+ ALLOCATE_MEM(5, 0, ARR({0xac, 0x0a})),
+ SET_ALLOCATOR(gen_pool_fixed_alloc, offset, 8),
+ ALLOCATE_MEM(3, 1, ARR({0xac, 0x0a, 0x2b})),
+ SET_ALLOCATOR(gen_pool_fixed_alloc, offset, 6),
+ ALLOCATE_MEM(2, 2, ARR({0xac, 0xba, 0x2b})),
+ SET_ALLOCATOR(gen_pool_fixed_alloc, offset, 30),
+ ALLOCATE_MEM(40, 3, ARR({0xac, 0xba, 0x2b, 0x00,
+ 0x00, 0x00, 0x00, 0xb0,
+ 0xaa, 0xaa, 0xaa, 0xaa,
+ 0xaa, 0xaa, 0xaa, 0xaa})),
+ FLUSH_MEM(),
+ END(),
+};
+
+
+/* Test first fit order align */
+static const struct test_command test_first_fit_order_align[] = {
+ SET_ALLOCATOR(gen_pool_first_fit_order_align, null, NULL),
+ ALLOCATE_MEM(5, 0, ARR({0xab, 0x02})),
+ ALLOCATE_MEM(3, 1, ARR({0xab, 0x02, 0x2b})),
+ ALLOCATE_MEM(2, 2, ARR({0xab, 0xb2, 0x2b})),
+ ALLOCATE_MEM(1, 3, ARR({0xab, 0xbe, 0x2b})),
+ ALLOCATE_MEM(1, 4, ARR({0xab, 0xbe, 0xeb})),
+ ALLOCATE_MEM(2, 5, ARR({0xab, 0xbe, 0xeb, 0x0b})),
+ FLUSH_MEM(),
+ END(),
+};
+
+
+/* 007 Test best fit */
+static const struct test_command test_best_fit[] = {
+ SET_ALLOCATOR(gen_pool_best_fit, null, NULL),
+ ALLOCATE_MEM(5, 0, ARR({0xab, 0x02})),
+ ALLOCATE_MEM(3, 1, ARR({0xab, 0xae})),
+ ALLOCATE_MEM(3, 2, ARR({0xab, 0xae, 0x2b})),
+ ALLOCATE_MEM(1, 3, ARR({0xab, 0xae, 0xeb})),
+ FREE_MEM(0, 0, ARR({0x00, 0xac, 0xeb})),
+ FREE_MEM(0, 2, ARR({0x00, 0xac, 0xc0})),
+ ALLOCATE_MEM(2, 0, ARR({0x00, 0xac, 0xcb})),
+ FLUSH_MEM(),
+ END(),
+};
+
+
+enum test_cases_indexes {
+ TEST_CASE_FIRST_FIT,
+ TEST_CASE_ULONG_SPAN,
+ TEST_CASE_FIRST_FIT_GAPS,
+ TEST_CASE_FIRST_FIT_ALIGN,
+ TEST_CASE_FIXED_DATA,
+ TEST_CASE_FIRST_FIT_ORDER_ALIGN,
+ TEST_CASE_BEST_FIT,
+ TEST_CASES_NUM,
+};
+
+static const struct test_command *test_cases[TEST_CASES_NUM] = {
+ [TEST_CASE_FIRST_FIT] = test_first_fit,
+ [TEST_CASE_ULONG_SPAN] = test_ulong_span,
+ [TEST_CASE_FIRST_FIT_GAPS] = test_first_fit_gaps,
+ [TEST_CASE_FIRST_FIT_ALIGN] = test_first_fit_align,
+ [TEST_CASE_FIXED_DATA] = test_fixed_data,
+ [TEST_CASE_FIRST_FIT_ORDER_ALIGN] = test_first_fit_order_align,
+ [TEST_CASE_BEST_FIT] = test_best_fit,
+};
+
+
+void test_genalloc(void)
+{
+ static struct gen_pool *pool;
+ unsigned long locations[ENTRIES];
+ char chunk[CHUNK_SIZE];
+ int retval;
+ unsigned int i;
+ const struct test_command *cmd;
+
+ pool = gen_pool_create(ALLOC_ORDER, -1);
+ if (unlikely(!pool)) {
+ pr_err("genalloc-selftest: no memory for pool.");
+ return;
+ }
+
+ retval = gen_pool_add_virt(pool, (unsigned long)chunk, 0,
+ CHUNK_SIZE, -1);
+ if (unlikely(retval)) {
+ pr_err("genalloc-selftest: could not register chunk.");
+ goto destroy_pool;
+ }
+
+ memset(locations, 0, ENTRIES * sizeof(unsigned long));
+ for (i = 0; i < TEST_CASES_NUM; i++)
+ for (cmd = test_cases[i]; cmd->command < CMD_END; cmd++)
+ callbacks[cmd->command](pool, cmd, locations);
+ pr_notice("genalloc-selftest: executed successfully %d tests",
+ TEST_CASES_NUM);
+
+destroy_pool:
+ gen_pool_destroy(pool);
+}
--
2.14.1
When a page is used for virtual memory, it is often necessary to obtain
a handler to the corresponding vm_struct, which refers to the virtually
continuous area generated when invoking vmalloc.
The struct page has a "mapping" field, which can be re-used, to store a
pointer to the parent area.
This will avoid more expensive searches, later on.
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/mm_types.h | 1 +
mm/vmalloc.c | 2 ++
2 files changed, 3 insertions(+)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index fd1af6b9591d..c3a4825e10c0 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -84,6 +84,7 @@ struct page {
void *s_mem; /* slab first object */
atomic_t compound_mapcount; /* first tail page */
/* page_deferred_list().next -- second tail page */
+ struct vm_struct *area;
};
/* Second double word */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ebff729cc956..61a1ca22b0f6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1536,6 +1536,7 @@ static void __vunmap(const void *addr, int deallocate_pages)
struct page *page = area->pages[i];
BUG_ON(!page);
+ page->area = NULL;
__free_pages(page, 0);
}
@@ -1705,6 +1706,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
area->nr_pages = i;
goto fail;
}
+ page->area = area;
area->pages[i] = page;
if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
cond_resched();
--
2.14.1
The MMU available in many systems running Linux can often provide R/O
protection to the memory pages it handles.
However, the MMU-based protection works efficiently only when said pages
contain exclusively data that will not need further modifications.
Statically allocated variables can be segregated into a dedicated
section, but this does not sit very well with dynamically allocated
ones.
Dynamic allocation does not provide, currently, any means for grouping
variables in memory pages that would contain exclusively data suitable
for conversion to read only access mode.
The allocator here provided (pmalloc - protectable memory allocator)
introduces the concept of pools of protectable memory.
A module can request a pool and then refer any allocation request to the
pool handler it has received.
Once all the chunks of memory associated to a specific pool are
initialized, the pool can be protected.
After this point, the pool can only be destroyed (it is up to the module
to avoid any further references to the memory from the pool, after
the destruction is invoked).
The latter case is mainly meant for releasing memory, when a module is
unloaded.
A module can have as many pools as needed, for example to support the
protection of data that is initialized in sufficiently distinct phases.
Since pmalloc memory is obtained from vmalloc, an attacker that has
gained access to the physical mapping, still has to identify where the
target of the attack is actually located.
At the same time, being also based on genalloc, pmalloc does not
generate as much trashing of the TLB as it would be caused by using
directly only vmalloc.
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/genalloc.h | 13 ++
include/linux/pmalloc.h | 242 ++++++++++++++++++++++++
include/linux/vmalloc.h | 1 +
lib/genalloc.c | 24 +++
mm/Kconfig | 7 +
mm/Makefile | 1 +
mm/pmalloc.c | 468 +++++++++++++++++++++++++++++++++++++++++++++++
mm/usercopy.c | 33 ++++
8 files changed, 789 insertions(+)
create mode 100644 include/linux/pmalloc.h
create mode 100644 mm/pmalloc.c
diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index 7b1a1f1d9985..3c936c4390df 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -231,6 +231,19 @@ void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma);
*/
void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size);
+/**
+ * gen_pool_flush_chunk() - drops all the allocations from a specific chunk
+ * @pool: the generic memory pool
+ * @chunk: The chunk to wipe clear.
+ *
+ * This is meant to be called only while destroying a pool. It's up to the
+ * caller to avoid races, but really, at this point the pool should have
+ * already been retired and it should have become unavailable for any other
+ * sort of operation.
+ */
+void gen_pool_flush_chunk(struct gen_pool *pool,
+ struct gen_pool_chunk *chunk);
+
/**
* gen_pool_for_each_chunk() - call func for every chunk of generic memory pool
* @pool: the generic memory pool
diff --git a/include/linux/pmalloc.h b/include/linux/pmalloc.h
new file mode 100644
index 000000000000..72550a325ca1
--- /dev/null
+++ b/include/linux/pmalloc.h
@@ -0,0 +1,242 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * pmalloc.h: Header for Protectable Memory Allocator
+ *
+ * (C) Copyright 2017 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+#ifndef _LINUX_PMALLOC_H
+#define _LINUX_PMALLOC_H
+
+
+#include <linux/genalloc.h>
+#include <linux/string.h>
+
+#define PMALLOC_DEFAULT_ALLOC_ORDER (-1)
+
+/*
+ * Library for dynamic allocation of pools of memory that can be,
+ * after initialization, marked as read-only.
+ *
+ * This is intended to complement __read_only_after_init, for those cases
+ * where either it is not possible to know the initialization value before
+ * init is completed, or the amount of data is variable and can be
+ * determined only at run-time.
+ *
+ * ***WARNING***
+ * The user of the API is expected to synchronize:
+ * 1) allocation,
+ * 2) writes to the allocated memory,
+ * 3) write protection of the pool,
+ * 4) freeing of the allocated memory, and
+ * 5) destruction of the pool.
+ *
+ * For a non-threaded scenario, this type of locking is not even required.
+ *
+ * Even if the library were to provide support for locking, point 2)
+ * would still depend on the user taking the lock.
+ */
+
+
+/**
+ * pmalloc_create_pool() - create a new protectable memory pool
+ * @name: the name of the pool, enforced to be unique
+ * @min_alloc_order: log2 of the minimum allocation size obtainable
+ * from the pool; -1 will pick sizeof(unsigned long)
+ *
+ * Creates a new (empty) memory pool for allocation of protectable
+ * memory. Memory will be allocated upon request (through pmalloc).
+ *
+ * Return:
+ * * pointer to the new pool - success
+ * * NULL - error
+ */
+struct gen_pool *pmalloc_create_pool(const char *name,
+ int min_alloc_order);
+
+/**
+ * is_pmalloc_object() - validates the existence of an alleged object
+ * @ptr: address of the object
+ * @n: size of the object, in bytes
+ *
+ * Return:
+ * * 0 - the object does not belong to pmalloc
+ * * 1 - the object belongs to pmalloc
+ * * \-1 - the object overlaps pmalloc memory incorrectly
+ */
+int is_pmalloc_object(const void *ptr, const unsigned long n);
+
+/**
+ * pmalloc_prealloc() - tries to allocate a memory chunk of the requested size
+ * @pool: handle to the pool to be used for memory allocation
+ * @size: amount of memory (in bytes) requested
+ *
+ * Prepares a chunk of the requested size.
+ * This is intended to both minimize latency in later memory requests and
+ * avoid sleeping during allocation.
+ * Memory allocated with prealloc is stored in one single chunk, as
+ * opposed to what is allocated on-demand when pmalloc runs out of free
+ * space already existing in the pool and has to invoke vmalloc.
+ * One additional advantage of pre-allocating larger chunks of memory is
+ * that the total slack tends to be smaller.
+ *
+ * Return:
+ * * true - the vmalloc call was successful
+ * * false - error
+ */
+bool pmalloc_prealloc(struct gen_pool *pool, size_t size);
+
+/**
+ * pmalloc() - allocate protectable memory from a pool
+ * @pool: handle to the pool to be used for memory allocation
+ * @size: amount of memory (in bytes) requested
+ * @gfp: flags for page allocation
+ *
+ * Allocates memory from an unprotected pool. If the pool doesn't have
+ * enough memory, and the request did not include GFP_ATOMIC, an attempt
+ * is made to add a new chunk of memory to the pool
+ * (a multiple of PAGE_SIZE), in order to fit the new request.
+ * Otherwise, NULL is returned.
+ *
+ * Return:
+ * * pointer to the memory requested - success
+ * * NULL - either no memory available or
+ * pool already read-only
+ */
+void *pmalloc(struct gen_pool *pool, size_t size, gfp_t gfp);
+
+
+/**
+ * pzalloc() - zero-initialized version of pmalloc
+ * @pool: handle to the pool to be used for memory allocation
+ * @size: amount of memory (in bytes) requested
+ * @gfp: flags for page allocation
+ *
+ * Executes pmalloc, initializing the memory requested to 0,
+ * before returning the pointer to it.
+ *
+ * Return:
+ * * pointer to the memory requested - success
+ * * NULL - either no memory available or
+ * pool already read-only
+ */
+static inline void *pzalloc(struct gen_pool *pool, size_t size, gfp_t gfp)
+{
+ return pmalloc(pool, size, gfp | __GFP_ZERO);
+}
+
+/**
+ * pmalloc_array() - allocates an array according to the parameters
+ * @pool: handle to the pool to be used for memory allocation
+ * @n: number of elements in the array
+ * @size: amount of memory (in bytes) requested for each element
+ * @flags: flags for page allocation
+ *
+ * Executes pmalloc, if it has a chance to succeed.
+ *
+ * Return:
+ * * the pmalloc result - success
+ * * NULL - error
+ */
+static inline void *pmalloc_array(struct gen_pool *pool, size_t n,
+ size_t size, gfp_t flags)
+{
+ if (unlikely(!(pool && n && size)))
+ return NULL;
+ return pmalloc(pool, n * size, flags);
+}
+
+/**
+ * pcalloc() - allocates a 0-initialized array according to the parameters
+ * @pool: handle to the pool to be used for memory allocation
+ * @n: number of elements in the array
+ * @size: amount of memory (in bytes) requested
+ * @flags: flags for page allocation
+ *
+ * Executes pmalloc_array, if it has a chance to succeed.
+ *
+ * Return:
+ * * the pmalloc result - success
+ * * NULL - error
+ */
+static inline void *pcalloc(struct gen_pool *pool, size_t n,
+ size_t size, gfp_t flags)
+{
+ return pmalloc_array(pool, n, size, flags | __GFP_ZERO);
+}
+
+/**
+ * pstrdup() - duplicate a string, using pmalloc as allocator
+ * @pool: handle to the pool to be used for memory allocation
+ * @s: string to duplicate
+ * @gfp: flags for page allocation
+ *
+ * Generates a copy of the given string, allocating sufficient memory
+ * from the given pmalloc pool.
+ *
+ * Return:
+ * * pointer to the replica - success
+ * * NULL - error
+ */
+static inline char *pstrdup(struct gen_pool *pool, const char *s, gfp_t gfp)
+{
+ size_t len;
+ char *buf;
+
+ if (unlikely(pool == NULL || s == NULL))
+ return NULL;
+
+ len = strlen(s) + 1;
+ buf = pmalloc(pool, len, gfp);
+ if (likely(buf))
+ strncpy(buf, s, len);
+ return buf;
+}
+
+/**
+ * pmalloc_protect_pool() - turn a read/write pool read-only
+ * @pool: the pool to protect
+ *
+ * Write-protects all the memory chunks assigned to the pool.
+ * This prevents any further allocation.
+ *
+ * Return:
+ * * 0 - success
+ * * -EINVAL - error
+ */
+int pmalloc_protect_pool(struct gen_pool *pool);
+
+/**
+ * pfree() - mark as unused memory that was previously in use
+ * @pool: handle to the pool to be used for memory allocation
+ * @addr: the beginning of the memory area to be freed
+ *
+ * The behavior of pfree is different, depending on the state of the
+ * protection.
+ * If the pool is not yet protected, the memory is marked as unused and
+ * will be available for further allocations.
+ * If the pool is already protected, the memory is marked as unused, but
+ * it will still be impossible to perform further allocation, because of
+ * the existing protection.
+ * The freed memory, in this case, will be truly released only when the
+ * pool is destroyed.
+ */
+static inline void pfree(struct gen_pool *pool, const void *addr)
+{
+ gen_pool_free(pool, (unsigned long)addr, 0);
+}
+
+/**
+ * pmalloc_destroy_pool() - destroys a pool and all the associated memory
+ * @pool: the pool to destroy
+ *
+ * All the memory that was allocated through pmalloc in the pool will be freed.
+ *
+ * Return:
+ * * 0 - success
+ * * -EINVAL - error
+ */
+int pmalloc_destroy_pool(struct gen_pool *pool);
+
+#endif
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 1e5d8c392f15..116d280cca53 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -20,6 +20,7 @@ struct notifier_block; /* in notifier.h */
#define VM_UNINITIALIZED 0x00000020 /* vm_struct is not fully initialized */
#define VM_NO_GUARD 0x00000040 /* don't add guard page */
#define VM_KASAN 0x00000080 /* has allocated kasan shadow memory */
+#define VM_PMALLOC 0x00000100 /* pmalloc area - see docs */
/* bits [20..32] reserved for arch specific ioremap internals */
/*
diff --git a/lib/genalloc.c b/lib/genalloc.c
index d505b959f888..a7ae088cbc5e 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -654,6 +654,30 @@ void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
}
EXPORT_SYMBOL(gen_pool_free);
+
+/**
+ * gen_pool_flush_chunk() - drops all the allocations from a specific chunk
+ * @pool: the generic memory pool
+ * @chunk: The chunk to wipe clear.
+ *
+ * This is meant to be called only while destroying a pool. It's up to the
+ * caller to avoid races, but really, at this point the pool should have
+ * already been retired and it should have become unavailable for any other
+ * sort of operation.
+ */
+void gen_pool_flush_chunk(struct gen_pool *pool,
+ struct gen_pool_chunk *chunk)
+{
+ size_t size;
+
+ size = chunk->end_addr + 1 - chunk->start_addr;
+ memset(chunk->entries, 0,
+ DIV_ROUND_UP(size >> pool->min_alloc_order * BITS_PER_ENTRY,
+ BITS_PER_BYTE));
+ atomic_long_set(&chunk->avail, size);
+}
+
+
/**
* gen_pool_for_each_chunk() - call func for every chunk of generic memory pool
* @pool: the generic memory pool
diff --git a/mm/Kconfig b/mm/Kconfig
index c782e8fb7235..016d29b9400b 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -760,3 +760,10 @@ config GUP_BENCHMARK
performance of get_user_pages_fast().
See tools/testing/selftests/vm/gup_benchmark.c
+
+config PROTECTABLE_MEMORY
+ bool
+ depends on MMU
+ depends on ARCH_HAS_SET_MEMORY
+ select GENERIC_ALLOCATOR
+ default y
diff --git a/mm/Makefile b/mm/Makefile
index e669f02c5a54..959fdbdac118 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -65,6 +65,7 @@ obj-$(CONFIG_SPARSEMEM) += sparse.o
obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
obj-$(CONFIG_SLOB) += slob.o
obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
+obj-$(CONFIG_PROTECTABLE_MEMORY) += pmalloc.o
obj-$(CONFIG_KSM) += ksm.o
obj-$(CONFIG_PAGE_POISONING) += page_poison.o
obj-$(CONFIG_SLAB) += slab.o
diff --git a/mm/pmalloc.c b/mm/pmalloc.c
new file mode 100644
index 000000000000..acdec0fbdde6
--- /dev/null
+++ b/mm/pmalloc.c
@@ -0,0 +1,468 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * pmalloc.c: Protectable Memory Allocator
+ *
+ * (C) Copyright 2017 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+#include <linux/printk.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/genalloc.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/atomic.h>
+#include <linux/rculist.h>
+#include <linux/set_memory.h>
+#include <linux/bug.h>
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+
+#include <linux/pmalloc.h>
+/*
+ * pmalloc_data contains the data specific to a pmalloc pool,
+ * in a format compatible with the design of gen_alloc.
+ * Some of the fields are used for exposing the corresponding parameter
+ * to userspace, through sysfs.
+ */
+struct pmalloc_data {
+ struct gen_pool *pool; /* Link back to the associated pool. */
+ bool protected; /* Status of the pool: RO or RW. */
+ struct kobj_attribute attr_protected; /* Sysfs attribute. */
+ struct kobj_attribute attr_avail; /* Sysfs attribute. */
+ struct kobj_attribute attr_size; /* Sysfs attribute. */
+ struct kobj_attribute attr_chunks; /* Sysfs attribute. */
+ struct kobject *pool_kobject;
+ struct list_head node; /* list of pools */
+};
+
+static LIST_HEAD(pmalloc_final_list);
+static LIST_HEAD(pmalloc_tmp_list);
+static struct list_head *pmalloc_list = &pmalloc_tmp_list;
+static DEFINE_MUTEX(pmalloc_mutex);
+static struct kobject *pmalloc_kobject;
+
+static ssize_t pmalloc_pool_show_protected(struct kobject *dev,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ struct pmalloc_data *data;
+
+ data = container_of(attr, struct pmalloc_data, attr_protected);
+ if (data->protected)
+ return sprintf(buf, "protected\n");
+ else
+ return sprintf(buf, "unprotected\n");
+}
+
+static ssize_t pmalloc_pool_show_avail(struct kobject *dev,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ struct pmalloc_data *data;
+
+ data = container_of(attr, struct pmalloc_data, attr_avail);
+ return sprintf(buf, "%lu\n",
+ (unsigned long)gen_pool_avail(data->pool));
+}
+
+static ssize_t pmalloc_pool_show_size(struct kobject *dev,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ struct pmalloc_data *data;
+
+ data = container_of(attr, struct pmalloc_data, attr_size);
+ return sprintf(buf, "%lu\n",
+ (unsigned long)gen_pool_size(data->pool));
+}
+
+static void pool_chunk_number(struct gen_pool *pool,
+ struct gen_pool_chunk *chunk, void *data)
+{
+ unsigned long *counter = data;
+
+ (*counter)++;
+}
+
+static ssize_t pmalloc_pool_show_chunks(struct kobject *dev,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ struct pmalloc_data *data;
+ unsigned long chunks_num = 0;
+
+ data = container_of(attr, struct pmalloc_data, attr_chunks);
+ gen_pool_for_each_chunk(data->pool, pool_chunk_number, &chunks_num);
+ return sprintf(buf, "%lu\n", chunks_num);
+}
+
+/* Exposes the pool and its attributes through sysfs. */
+static struct kobject *pmalloc_connect(struct pmalloc_data *data)
+{
+ const struct attribute *attrs[] = {
+ &data->attr_protected.attr,
+ &data->attr_avail.attr,
+ &data->attr_size.attr,
+ &data->attr_chunks.attr,
+ NULL
+ };
+ struct kobject *kobj;
+
+ kobj = kobject_create_and_add(data->pool->name, pmalloc_kobject);
+ if (unlikely(!kobj))
+ return NULL;
+
+ if (unlikely(sysfs_create_files(kobj, attrs) < 0)) {
+ kobject_put(kobj);
+ kobj = NULL;
+ }
+ return kobj;
+}
+
+/* Removes the pool and its attributes from sysfs. */
+static void pmalloc_disconnect(struct pmalloc_data *data,
+ struct kobject *kobj)
+{
+ const struct attribute *attrs[] = {
+ &data->attr_protected.attr,
+ &data->attr_avail.attr,
+ &data->attr_size.attr,
+ &data->attr_chunks.attr,
+ NULL
+ };
+
+ sysfs_remove_files(kobj, attrs);
+ kobject_put(kobj);
+}
+
+/* Declares an attribute of the pool. */
+#define pmalloc_attr_init(data, attr_name) \
+do { \
+ sysfs_attr_init(&data->attr_##attr_name.attr); \
+ data->attr_##attr_name.attr.name = #attr_name; \
+ data->attr_##attr_name.attr.mode = VERIFY_OCTAL_PERMISSIONS(0400); \
+ data->attr_##attr_name.show = pmalloc_pool_show_##attr_name; \
+} while (0)
+
+struct gen_pool *pmalloc_create_pool(const char *name, int min_alloc_order)
+{
+ struct gen_pool *pool;
+ const char *pool_name;
+ struct pmalloc_data *data;
+
+ if (unlikely(!name)) {
+ WARN(true, "unnamed pool");
+ return NULL;
+ }
+
+ if (min_alloc_order < 0)
+ min_alloc_order = ilog2(sizeof(unsigned long));
+
+ pool = gen_pool_create(min_alloc_order, NUMA_NO_NODE);
+ if (unlikely(!pool))
+ return NULL;
+
+ mutex_lock(&pmalloc_mutex);
+ list_for_each_entry(data, pmalloc_list, node)
+ if (!strcmp(name, data->pool->name))
+ goto same_name_err;
+
+ pool_name = kstrdup(name, GFP_KERNEL);
+ if (unlikely(!pool_name))
+ goto name_alloc_err;
+
+ data = kzalloc(sizeof(struct pmalloc_data), GFP_KERNEL);
+ if (unlikely(!data))
+ goto data_alloc_err;
+
+ data->protected = false;
+ data->pool = pool;
+ pmalloc_attr_init(data, protected);
+ pmalloc_attr_init(data, avail);
+ pmalloc_attr_init(data, size);
+ pmalloc_attr_init(data, chunks);
+ pool->data = data;
+ pool->name = pool_name;
+
+ list_add(&data->node, pmalloc_list);
+ if (pmalloc_list == &pmalloc_final_list)
+ data->pool_kobject = pmalloc_connect(data);
+ mutex_unlock(&pmalloc_mutex);
+ return pool;
+
+data_alloc_err:
+ kfree(pool_name);
+name_alloc_err:
+same_name_err:
+ mutex_unlock(&pmalloc_mutex);
+ gen_pool_destroy(pool);
+ return NULL;
+}
+
+static inline bool chunk_tagging(void *chunk, bool tag)
+{
+ struct vm_struct *area;
+ struct page *page;
+
+ if (!is_vmalloc_addr(chunk))
+ return false;
+
+ page = vmalloc_to_page(chunk);
+ if (unlikely(!page))
+ return false;
+
+ area = page->area;
+ if (tag)
+ area->flags |= VM_PMALLOC;
+ else
+ area->flags &= ~VM_PMALLOC;
+ return true;
+}
+
+
+static inline bool tag_chunk(void *chunk)
+{
+ return chunk_tagging(chunk, true);
+}
+
+
+static inline bool untag_chunk(void *chunk)
+{
+ return chunk_tagging(chunk, false);
+}
+
+enum {
+ INVALID_PMALLOC_OBJECT = -1,
+ NOT_PMALLOC_OBJECT = 0,
+ VALID_PMALLOC_OBJECT = 1,
+};
+
+int is_pmalloc_object(const void *ptr, const unsigned long n)
+{
+ struct vm_struct *area;
+ struct page *page;
+ unsigned long area_start;
+ unsigned long area_end;
+ unsigned long object_start;
+ unsigned long object_end;
+
+
+ /*
+ * is_pmalloc_object gets called pretty late, so chances are high
+ * that the object is indeed of vmalloc type
+ */
+ if (unlikely(!is_vmalloc_addr(ptr)))
+ return NOT_PMALLOC_OBJECT;
+
+ page = vmalloc_to_page(ptr);
+ if (unlikely(!page))
+ return NOT_PMALLOC_OBJECT;
+
+ area = page->area;
+
+ if (likely(!(area->flags & VM_PMALLOC)))
+ return NOT_PMALLOC_OBJECT;
+
+ area_start = (unsigned long)area->addr;
+ area_end = area_start + area->nr_pages * PAGE_SIZE - 1;
+ object_start = (unsigned long)ptr;
+ object_end = object_start + n - 1;
+
+ if (likely((area_start <= object_start) &&
+ (object_end <= area_end)))
+ return VALID_PMALLOC_OBJECT;
+ else
+ return INVALID_PMALLOC_OBJECT;
+}
+
+
+bool pmalloc_prealloc(struct gen_pool *pool, size_t size)
+{
+ void *chunk;
+ size_t chunk_size;
+ bool add_error;
+
+ /* Expand pool */
+ chunk_size = roundup(size, PAGE_SIZE);
+ chunk = vmalloc(chunk_size);
+ if (unlikely(chunk == NULL))
+ return false;
+
+ /* Locking is already done inside gen_pool_add */
+ add_error = gen_pool_add(pool, (unsigned long)chunk, chunk_size,
+ NUMA_NO_NODE);
+ if (unlikely(add_error != 0))
+ goto abort;
+
+ return true;
+abort:
+ vfree_atomic(chunk);
+ return false;
+
+}
+
+void *pmalloc(struct gen_pool *pool, size_t size, gfp_t gfp)
+{
+ void *chunk;
+ size_t chunk_size;
+ bool add_error;
+ unsigned long retval;
+
+ if (unlikely(((struct pmalloc_data *)(pool->data))->protected)) {
+ WARN(true, "pool %s is already protected", pool->name);
+ return NULL;
+ }
+
+retry_alloc_from_pool:
+ retval = gen_pool_alloc(pool, size);
+ if (retval)
+ goto return_allocation;
+
+ if (unlikely((gfp & __GFP_ATOMIC))) {
+ if (unlikely((gfp & __GFP_NOFAIL)))
+ goto retry_alloc_from_pool;
+ else
+ return NULL;
+ }
+
+ /* Expand pool */
+ chunk_size = roundup(size, PAGE_SIZE);
+ chunk = vmalloc(chunk_size);
+ if (unlikely(!chunk)) {
+ if (unlikely((gfp & __GFP_NOFAIL)))
+ goto retry_alloc_from_pool;
+ else
+ return NULL;
+ }
+ if (unlikely(!tag_chunk(chunk)))
+ goto free;
+
+ /* Locking is already done inside gen_pool_add */
+ add_error = gen_pool_add(pool, (unsigned long)chunk, chunk_size,
+ NUMA_NO_NODE);
+ if (unlikely(add_error))
+ goto abort;
+
+ retval = gen_pool_alloc(pool, size);
+ if (retval) {
+return_allocation:
+ *(size_t *)retval = size;
+ if (gfp & __GFP_ZERO)
+ memset((void *)retval, 0, size);
+ return (void *)retval;
+ }
+ /*
+ * Here there is no test for __GFP_NO_FAIL because, in case of
+ * concurrent allocation, one thread might add a chunk to the
+ * pool and this memory could be allocated by another thread,
+ * before the first thread gets a chance to use it.
+ * As long as vmalloc succeeds, it's ok to retry.
+ */
+ goto retry_alloc_from_pool;
+abort:
+ untag_chunk(chunk);
+free:
+ vfree_atomic(chunk);
+ return NULL;
+}
+
+static void pmalloc_chunk_set_protection(struct gen_pool *pool,
+ struct gen_pool_chunk *chunk,
+ void *data)
+{
+ const bool *flag = data;
+ size_t chunk_size = chunk->end_addr + 1 - chunk->start_addr;
+ unsigned long pages = chunk_size / PAGE_SIZE;
+
+ if (unlikely(chunk_size & (PAGE_SIZE - 1))) {
+ WARN(true, "Chunk size is not a multiple of PAGE_SIZE.");
+ return;
+ }
+
+ if (*flag)
+ set_memory_ro(chunk->start_addr, pages);
+ else
+ set_memory_rw(chunk->start_addr, pages);
+}
+
+static int pmalloc_pool_set_protection(struct gen_pool *pool, bool protection)
+{
+ struct pmalloc_data *data;
+ struct gen_pool_chunk *chunk;
+
+ data = pool->data;
+ if (unlikely(data->protected == protection)) {
+ WARN(true, "The pool %s is already protected as requested",
+ pool->name);
+ return 0;
+ }
+ data->protected = protection;
+ list_for_each_entry(chunk, &(pool)->chunks, next_chunk)
+ pmalloc_chunk_set_protection(pool, chunk, &protection);
+ return 0;
+}
+
+int pmalloc_protect_pool(struct gen_pool *pool)
+{
+ return pmalloc_pool_set_protection(pool, true);
+}
+
+
+static void pmalloc_chunk_free(struct gen_pool *pool,
+ struct gen_pool_chunk *chunk, void *data)
+{
+ untag_chunk(chunk);
+ gen_pool_flush_chunk(pool, chunk);
+ vfree_atomic((void *)chunk->start_addr);
+}
+
+
+int pmalloc_destroy_pool(struct gen_pool *pool)
+{
+ struct pmalloc_data *data;
+
+ data = pool->data;
+
+ mutex_lock(&pmalloc_mutex);
+ list_del(&data->node);
+ mutex_unlock(&pmalloc_mutex);
+
+ if (likely(data->pool_kobject))
+ pmalloc_disconnect(data, data->pool_kobject);
+
+ pmalloc_pool_set_protection(pool, false);
+ gen_pool_for_each_chunk(pool, pmalloc_chunk_free, NULL);
+ gen_pool_destroy(pool);
+ kfree(data);
+ return 0;
+}
+
+/*
+ * When the sysfs is ready to receive registrations, connect all the
+ * pools previously created. Also enable further pools to be connected
+ * right away.
+ */
+static int __init pmalloc_late_init(void)
+{
+ struct pmalloc_data *data, *n;
+
+ pmalloc_kobject = kobject_create_and_add("pmalloc", kernel_kobj);
+
+ mutex_lock(&pmalloc_mutex);
+ pmalloc_list = &pmalloc_final_list;
+
+ if (likely(pmalloc_kobject != NULL)) {
+ list_for_each_entry_safe(data, n, &pmalloc_tmp_list, node) {
+ list_move(&data->node, &pmalloc_final_list);
+ pmalloc_connect(data);
+ }
+ }
+ mutex_unlock(&pmalloc_mutex);
+ return 0;
+}
+late_initcall(pmalloc_late_init);
diff --git a/mm/usercopy.c b/mm/usercopy.c
index e9e9325f7638..946ce051e296 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -240,6 +240,36 @@ static inline void check_heap_object(const void *ptr, unsigned long n,
}
}
+#ifdef CONFIG_PROTECTABLE_MEMORY
+
+int is_pmalloc_object(const void *ptr, const unsigned long n);
+
+static void check_pmalloc_object(const void *ptr, unsigned long n,
+ bool to_user)
+{
+ int retv;
+
+ retv = is_pmalloc_object(ptr, n);
+ if (unlikely(retv)) {
+ if (unlikely(!to_user))
+ usercopy_abort("pmalloc",
+ "trying to write to pmalloc object",
+ to_user, (const unsigned long)ptr, n);
+ if (retv < 0)
+ usercopy_abort("pmalloc",
+ "invalid pmalloc object",
+ to_user, (const unsigned long)ptr, n);
+ }
+}
+
+#else
+
+static void check_pmalloc_object(const void *ptr, unsigned long n,
+ bool to_user)
+{
+}
+#endif
+
/*
* Validates that the given object is:
* - not bogus address
@@ -277,5 +307,8 @@ void __check_object_size(const void *ptr, unsigned long n, bool to_user)
/* Check for object in kernel to avoid text exposure. */
check_kernel_text_object((const unsigned long)ptr, n, to_user);
+
+ /* Check if object is from a pmalloc chunk. */
+ check_pmalloc_object(ptr, n, to_user);
}
EXPORT_SYMBOL(__check_object_size);
--
2.14.1
Add basic self-test functionality for pmalloc.
The testing is introduced as early as possible, right after the main
dependency, genalloc, has passed successfully, so that it can help
diagnosing failures in pmalloc users.
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/test_pmalloc.h | 24 +++++++++++
init/main.c | 2 +
mm/Kconfig | 10 +++++
mm/Makefile | 1 +
mm/test_pmalloc.c | 100 +++++++++++++++++++++++++++++++++++++++++++
5 files changed, 137 insertions(+)
create mode 100644 include/linux/test_pmalloc.h
create mode 100644 mm/test_pmalloc.c
diff --git a/include/linux/test_pmalloc.h b/include/linux/test_pmalloc.h
new file mode 100644
index 000000000000..c7e2e451c17c
--- /dev/null
+++ b/include/linux/test_pmalloc.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * test_pmalloc.h
+ *
+ * (C) Copyright 2018 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+
+#ifndef __LINUX_TEST_PMALLOC_H
+#define __LINUX_TEST_PMALLOC_H
+
+
+#ifdef CONFIG_TEST_PROTECTABLE_MEMORY
+
+void test_pmalloc(void);
+
+#else
+
+static inline void test_pmalloc(void){};
+
+#endif
+
+#endif
diff --git a/init/main.c b/init/main.c
index 2bf1312fd2fe..ea44c940070a 100644
--- a/init/main.c
+++ b/init/main.c
@@ -91,6 +91,7 @@
#include <linux/rodata_test.h>
#include <linux/jump_label.h>
#include <linux/test_genalloc.h>
+#include <linux/test_pmalloc.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -663,6 +664,7 @@ asmlinkage __visible void __init start_kernel(void)
mem_encrypt_init();
test_genalloc();
+ test_pmalloc();
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
diff --git a/mm/Kconfig b/mm/Kconfig
index 016d29b9400b..47b0843b02d2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -767,3 +767,13 @@ config PROTECTABLE_MEMORY
depends on ARCH_HAS_SET_MEMORY
select GENERIC_ALLOCATOR
default y
+
+config TEST_PROTECTABLE_MEMORY
+ bool "Run self test for pmalloc memory allocator"
+ depends on MMU
+ depends on ARCH_HAS_SET_MEMORY
+ select PROTECTABLE_MEMORY
+ default n
+ help
+ Tries to verify that pmalloc works correctly and that the memory
+ is effectively protected.
diff --git a/mm/Makefile b/mm/Makefile
index 959fdbdac118..1de4be5fd0bc 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -66,6 +66,7 @@ obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
obj-$(CONFIG_SLOB) += slob.o
obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
obj-$(CONFIG_PROTECTABLE_MEMORY) += pmalloc.o
+obj-$(CONFIG_TEST_PROTECTABLE_MEMORY) += test_pmalloc.o
obj-$(CONFIG_KSM) += ksm.o
obj-$(CONFIG_PAGE_POISONING) += page_poison.o
obj-$(CONFIG_SLAB) += slab.o
diff --git a/mm/test_pmalloc.c b/mm/test_pmalloc.c
new file mode 100644
index 000000000000..df7ecc91c6a4
--- /dev/null
+++ b/mm/test_pmalloc.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * test_pmalloc.c
+ *
+ * (C) Copyright 2018 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+#include <linux/pmalloc.h>
+#include <linux/mm.h>
+#include <linux/test_pmalloc.h>
+#include <linux/bug.h>
+
+#define SIZE_1 (PAGE_SIZE * 3)
+#define SIZE_2 1000
+
+static inline bool validate_alloc(bool expected, void *addr,
+ unsigned long size)
+{
+ bool test;
+
+ test = is_pmalloc_object(addr, size) > 0;
+ pr_notice("must be %s: %s",
+ expected ? "ok" : "no", test ? "ok" : "no");
+ return test == expected;
+}
+
+#define is_alloc_ok(variable, size) \
+ validate_alloc(true, variable, size)
+
+#define is_alloc_no(variable, size) \
+ validate_alloc(false, variable, size)
+
+void test_pmalloc(void)
+{
+ struct gen_pool *pool_unprot;
+ struct gen_pool *pool_prot;
+ void *var_prot, *var_unprot, *var_vmall;
+
+ pr_notice("pmalloc-selftest");
+ pool_unprot = pmalloc_create_pool("unprotected", 0);
+ if (unlikely(!pool_unprot))
+ goto error;
+ pool_prot = pmalloc_create_pool("protected", 0);
+ if (unlikely(!(pool_prot)))
+ goto error_release;
+
+ pr_notice("Testing allocation capability");
+ var_unprot = pmalloc(pool_unprot, SIZE_1 - 1, GFP_KERNEL);
+ var_prot = pmalloc(pool_prot, SIZE_1, GFP_KERNEL);
+ *(int *)var_prot = 0;
+ var_vmall = vmalloc(SIZE_2);
+
+
+ pr_notice("Test correctness of is_pmalloc_object()");
+ WARN_ON(unlikely(!is_alloc_ok(var_unprot, 10)));
+ WARN_ON(unlikely(!is_alloc_ok(var_unprot, SIZE_1)));
+ WARN_ON(unlikely(!is_alloc_ok(var_unprot, PAGE_SIZE)));
+ WARN_ON(unlikely(!is_alloc_no(var_unprot, SIZE_1 + 1)));
+ WARN_ON(unlikely(!is_alloc_no(var_vmall, 10)));
+
+
+ pfree(pool_unprot, var_unprot);
+ vfree(var_vmall);
+
+ pmalloc_protect_pool(pool_prot);
+
+ /*
+ * This will intentionally trigger a WARN, because the pool being
+ * allocated from is already protected.
+ */
+ pr_notice("Test allocation from a protected pool."
+ "Expect WARN in pmalloc");
+ if (unlikely(pmalloc(pool_prot, 10, GFP_KERNEL)))
+ WARN(true, "no memory from a protected pool");
+
+ /*
+ * This will intentionally trigger a WARN because the pool being
+ * destroyed is not protected, which is unusual and should happen
+ * on error paths only, where probably other warnings are already
+ * displayed.
+ */
+ pr_notice("pmalloc-selftest:"
+ " Expect WARN in pmalloc_pool_set_protection below.");
+ pmalloc_destroy_pool(pool_unprot);
+ pr_notice("pmalloc-selftest:"
+ "Critical point for expected WARN passed.");
+
+ /* This must not cause WARNings */
+ pr_notice("pmalloc-selftest:"
+ "Expect no WARN below.");
+ pmalloc_destroy_pool(pool_prot);
+ pr_notice("pmalloc-selftest:"
+ "Critical point for unexpected WARN passed.");
+ return;
+error_release:
+ pmalloc_destroy_pool(pool_unprot);
+error:
+ WARN(true, "Unable to allocate memory for pmalloc selftest.");
+}
--
2.14.1
Verify that pmalloc read-only protection is in place: trying to
overwrite a protected variable will crash the kernel.
Signed-off-by: Igor Stoppa <[email protected]>
---
drivers/misc/lkdtm.h | 1 +
drivers/misc/lkdtm_core.c | 3 +++
drivers/misc/lkdtm_perms.c | 28 ++++++++++++++++++++++++++++
3 files changed, 32 insertions(+)
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
index 9e513dcfd809..dcda3ae76ceb 100644
--- a/drivers/misc/lkdtm.h
+++ b/drivers/misc/lkdtm.h
@@ -38,6 +38,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void);
void __init lkdtm_perms_init(void);
void lkdtm_WRITE_RO(void);
void lkdtm_WRITE_RO_AFTER_INIT(void);
+void lkdtm_WRITE_RO_PMALLOC(void);
void lkdtm_WRITE_KERN(void);
void lkdtm_EXEC_DATA(void);
void lkdtm_EXEC_STACK(void);
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 2154d1bfd18b..c9fd42bda6ee 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -155,6 +155,9 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(ACCESS_USERSPACE),
CRASHTYPE(WRITE_RO),
CRASHTYPE(WRITE_RO_AFTER_INIT),
+#ifdef CONFIG_PROTECTABLE_MEMORY
+ CRASHTYPE(WRITE_RO_PMALLOC),
+#endif
CRASHTYPE(WRITE_KERN),
CRASHTYPE(REFCOUNT_INC_OVERFLOW),
CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
diff --git a/drivers/misc/lkdtm_perms.c b/drivers/misc/lkdtm_perms.c
index 53b85c9d16b8..0ac9023fd2b0 100644
--- a/drivers/misc/lkdtm_perms.c
+++ b/drivers/misc/lkdtm_perms.c
@@ -9,6 +9,7 @@
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/uaccess.h>
+#include <linux/pmalloc.h>
#include <asm/cacheflush.h>
/* Whether or not to fill the target memory area with do_nothing(). */
@@ -104,6 +105,33 @@ void lkdtm_WRITE_RO_AFTER_INIT(void)
*ptr ^= 0xabcd1234;
}
+#ifdef CONFIG_PROTECTABLE_MEMORY
+void lkdtm_WRITE_RO_PMALLOC(void)
+{
+ struct gen_pool *pool;
+ int *i;
+
+ pool = pmalloc_create_pool("pool", 0);
+ if (unlikely(!pool)) {
+ pr_info("Failed preparing pool for pmalloc test.");
+ return;
+ }
+
+ i = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL);
+ if (unlikely(!i)) {
+ pr_info("Failed allocating memory for pmalloc test.");
+ pmalloc_destroy_pool(pool);
+ return;
+ }
+
+ *i = INT_MAX;
+ pmalloc_protect_pool(pool);
+
+ pr_info("attempting bad pmalloc write at %p\n", i);
+ *i = 0;
+}
+#endif
+
void lkdtm_WRITE_KERN(void)
{
size_t size;
--
2.14.1
Detailed documentation about the protectable memory allocator.
Signed-off-by: Igor Stoppa <[email protected]>
---
Documentation/core-api/index.rst | 1 +
Documentation/core-api/pmalloc.rst | 111 +++++++++++++++++++++++++++++++++++++
2 files changed, 112 insertions(+)
create mode 100644 Documentation/core-api/pmalloc.rst
diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst
index c670a8031786..8f5de42d6571 100644
--- a/Documentation/core-api/index.rst
+++ b/Documentation/core-api/index.rst
@@ -25,6 +25,7 @@ Core utilities
genalloc
errseq
printk-formats
+ pmalloc
Interfaces for kernel debugging
===============================
diff --git a/Documentation/core-api/pmalloc.rst b/Documentation/core-api/pmalloc.rst
new file mode 100644
index 000000000000..8fb9c9d3171b
--- /dev/null
+++ b/Documentation/core-api/pmalloc.rst
@@ -0,0 +1,111 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Protectable memory allocator
+============================
+
+Purpose
+-------
+
+The pmalloc library is meant to provide R/O status to data that, for some
+reason, could neither be declared as constant, nor could it take advantage
+of the qualifier __ro_after_init, but is write-once and read-only in spirit.
+It protects data from both accidental and malicious overwrites.
+
+Example: A policy that is loaded from userspace.
+
+
+Concept
+-------
+
+pmalloc builds on top of genalloc, using the same concept of memory pools.
+
+The value added by pmalloc is that now the memory contained in a pool can
+become R/O, for the rest of the life of the pool.
+
+Different kernel drivers and threads can use different pools, for finer
+control of what becomes R/O and when. And for improved lockless concurrency.
+
+
+Caveats
+-------
+
+- Memory freed while a pool is not yet protected will be reused.
+
+- Once a pool is protected, it's not possible to allocate any more memory
+ from it.
+
+- Memory "freed" from a protected pool indicates that such memory is not
+ in use anymore by the requester; however, it will not become available
+ for further use, until the pool is destroyed.
+
+- pmalloc does not provide locking support with respect to allocating vs
+ protecting an individual pool, for performance reasons.
+ It is recommended not to share the same pool between unrelated functions.
+ Should sharing be a necessity, the user of the shared pool is expected
+ to implement locking for that pool.
+
+- pmalloc uses genalloc to optimize the use of the space it allocates
+ through vmalloc. Some more TLB entries will be used, however less than
+ in the case of using vmalloc directly. The exact number depends on the
+ size of each allocation request and possible slack.
+
+- Considering that not much data is supposed to be dynamically allocated
+ and then marked as read-only, it shouldn't be an issue that the address
+ range for pmalloc is limited, on 32-bit systems.
+
+- Regarding SMP systems, the allocations are expected to happen mostly
+ during an initial transient, after which there should be no more need to
+ perform cross-processor synchronizations of page tables.
+
+- To facilitate the conversion of existing code to pmalloc pools, several
+ helper functions are provided, mirroring their kmalloc counterparts.
+
+
+Use
+---
+
+The typical sequence, when using pmalloc, is:
+
+1. create a pool
+
+.. kernel-doc:: include/linux/pmalloc.h
+ :functions: pmalloc_create_pool
+
+2. [optional] pre-allocate some memory in the pool
+
+.. kernel-doc:: include/linux/pmalloc.h
+ :functions: pmalloc_prealloc
+
+3. issue one or more allocation requests to the pool with locking as needed
+
+.. kernel-doc:: include/linux/pmalloc.h
+ :functions: pmalloc
+
+.. kernel-doc:: include/linux/pmalloc.h
+ :functions: pzalloc
+
+4. initialize the memory obtained with desired values
+
+5. [optional] iterate over points 3 & 4 as needed
+
+6. write-protect the pool
+
+.. kernel-doc:: include/linux/pmalloc.h
+ :functions: pmalloc_protect_pool
+
+7. use in read-only mode the handles obtained through the allocations
+
+8. [optional] release all the memory allocated
+
+.. kernel-doc:: include/linux/pmalloc.h
+ :functions: pfree
+
+9. [optional, but depends on point 8] destroy the pool
+
+.. kernel-doc:: include/linux/pmalloc.h
+ :functions: pmalloc_destroy_pool
+
+API
+---
+
+.. kernel-doc:: include/linux/pmalloc.h
--
2.14.1
Hi Igor,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on next-20180223]
[also build test ERROR on v4.16-rc3]
[cannot apply to linus/master mmotm/master char-misc/char-misc-testing v4.16-rc3 v4.16-rc2 v4.16-rc1]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Igor-Stoppa/mm-security-ro-protection-for-dynamic-data/20180302-232215
config: i386-randconfig-x004-201808 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All error/warnings (new ones prefixed by >>):
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c: In function 'gen_pool_free':
>> lib/genalloc.c:616:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Trying to free unallocated memory"
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
>> lib/genalloc.c:615:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:617:23: note: format string is defined here
" from pool %s", pool);
~^
In file included from include/asm-generic/bug.h:5:0,
from arch/x86/include/asm/bug.h:83,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
>> lib/genalloc.c:624:17: error: implicit declaration of function 'exit_test'; did you mean 'exit_sem'? [-Werror=implicit-function-declaration]
if (unlikely(exit_test(boundary < 0))) {
^
include/linux/compiler.h:77:42: note: in definition of macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c:626:16: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
WARN(true, "Corrupted pool %s", pool);
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:626:5: note: in expansion of macro 'WARN'
WARN(true, "Corrupted pool %s", pool);
^~~~
lib/genalloc.c:634:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Size provided differs from size "
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:633:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:635:31: note: format string is defined here
"measured from pool %s", pool);
~^
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c:643:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Unexpected bitmap collision while"
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:642:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:644:36: note: format string is defined here
" freeing memory in pool %s", pool);
~^
cc1: some warnings being treated as errors
vim +624 lib/genalloc.c
609
610 rcu_read_lock();
611 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
612 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
613 if (unlikely(addr + size - 1 > chunk->end_addr)) {
614 rcu_read_unlock();
> 615 WARN(true,
> 616 "Trying to free unallocated memory"
617 " from pool %s", pool);
618 return;
619 }
620 start_entry = (addr - chunk->start_addr) >> order;
621 remaining_entries = (chunk->end_addr - addr) >> order;
622 boundary = get_boundary(chunk->entries, start_entry,
623 remaining_entries);
> 624 if (unlikely(exit_test(boundary < 0))) {
625 rcu_read_unlock();
626 WARN(true, "Corrupted pool %s", pool);
627 return;
628 }
629 nentries = boundary - start_entry;
630 if (unlikely(size && (nentries !=
631 mem_to_units(size, order)))) {
632 rcu_read_unlock();
633 WARN(true,
634 "Size provided differs from size "
635 "measured from pool %s", pool);
636 return;
637 }
638 remain = alter_bitmap_ll(CLEAR_BITS, chunk->entries,
639 start_entry, nentries);
640 if (unlikely(remain)) {
641 rcu_read_unlock();
642 WARN(true,
643 "Unexpected bitmap collision while"
644 " freeing memory in pool %s", pool);
645 return;
646 }
647 atomic_long_add(nentries << order, &chunk->avail);
648 rcu_read_unlock();
649 return;
650 }
651 }
652 rcu_read_unlock();
653 WARN(true, "address not found in pool %s", pool->name);
654 }
655 EXPORT_SYMBOL(gen_pool_free);
656
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
Hi Igor,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on next-20180223]
[also build test WARNING on v4.16-rc3]
[cannot apply to linus/master mmotm/master char-misc/char-misc-testing v4.16-rc3 v4.16-rc2 v4.16-rc1]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Igor-Stoppa/mm-security-ro-protection-for-dynamic-data/20180302-232215
config: i386-randconfig-x007-201808 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All warnings (new ones prefixed by >>):
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c: In function 'gen_pool_free':
lib/genalloc.c:616:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Trying to free unallocated memory"
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:615:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:617:23: note: format string is defined here
" from pool %s", pool);
~^
In file included from include/asm-generic/bug.h:5:0,
from arch/x86/include/asm/bug.h:83,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c:624:17: error: implicit declaration of function 'exit_test'; did you mean 'exit_sem'? [-Werror=implicit-function-declaration]
if (unlikely(exit_test(boundary < 0))) {
^
include/linux/compiler.h:58:30: note: in definition of macro '__trace_if'
if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
^~~~
>> lib/genalloc.c:624:4: note: in expansion of macro 'if'
if (unlikely(exit_test(boundary < 0))) {
^~
include/linux/compiler.h:48:24: note: in expansion of macro '__branch_check__'
# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
^~~~~~~~~~~~~~~~
>> lib/genalloc.c:624:8: note: in expansion of macro 'unlikely'
if (unlikely(exit_test(boundary < 0))) {
^~~~~~~~
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c:626:16: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
WARN(true, "Corrupted pool %s", pool);
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:626:5: note: in expansion of macro 'WARN'
WARN(true, "Corrupted pool %s", pool);
^~~~
lib/genalloc.c:634:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Size provided differs from size "
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:633:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:635:31: note: format string is defined here
"measured from pool %s", pool);
~^
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c:643:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Unexpected bitmap collision while"
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:642:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:644:36: note: format string is defined here
" freeing memory in pool %s", pool);
~^
cc1: some warnings being treated as errors
vim +/if +624 lib/genalloc.c
609
610 rcu_read_lock();
611 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
612 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
613 if (unlikely(addr + size - 1 > chunk->end_addr)) {
614 rcu_read_unlock();
615 WARN(true,
616 "Trying to free unallocated memory"
617 " from pool %s", pool);
618 return;
619 }
620 start_entry = (addr - chunk->start_addr) >> order;
621 remaining_entries = (chunk->end_addr - addr) >> order;
622 boundary = get_boundary(chunk->entries, start_entry,
623 remaining_entries);
> 624 if (unlikely(exit_test(boundary < 0))) {
625 rcu_read_unlock();
626 WARN(true, "Corrupted pool %s", pool);
627 return;
628 }
629 nentries = boundary - start_entry;
630 if (unlikely(size && (nentries !=
631 mem_to_units(size, order)))) {
632 rcu_read_unlock();
633 WARN(true,
634 "Size provided differs from size "
635 "measured from pool %s", pool);
636 return;
637 }
638 remain = alter_bitmap_ll(CLEAR_BITS, chunk->entries,
639 start_entry, nentries);
640 if (unlikely(remain)) {
641 rcu_read_unlock();
642 WARN(true,
643 "Unexpected bitmap collision while"
644 " freeing memory in pool %s", pool);
645 return;
646 }
647 atomic_long_add(nentries << order, &chunk->avail);
648 rcu_read_unlock();
649 return;
650 }
651 }
652 rcu_read_unlock();
653 WARN(true, "address not found in pool %s", pool->name);
654 }
655 EXPORT_SYMBOL(gen_pool_free);
656
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
Hi Igor,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on next-20180223]
[cannot apply to linus/master mmotm/master char-misc/char-misc-testing v4.16-rc3 v4.16-rc2 v4.16-rc1 v4.16-rc3]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Igor-Stoppa/mm-security-ro-protection-for-dynamic-data/20180302-232215
reproduce:
# apt-get install sparse
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__
sparse warnings: (new ones prefixed by >>)
lib/genalloc.c:624:29: sparse: undefined identifier 'exit_test'
>> lib/genalloc.c:624:29: sparse: call with no type!
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c: In function 'gen_pool_free':
lib/genalloc.c:616:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Trying to free unallocated memory"
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:615:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:617:23: note: format string is defined here
" from pool %s", pool);
~^
In file included from include/asm-generic/bug.h:5:0,
from arch/x86/include/asm/bug.h:83,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c:624:17: error: implicit declaration of function 'exit_test'; did you mean 'exit_sem'? [-Werror=implicit-function-declaration]
if (unlikely(exit_test(boundary < 0))) {
^
include/linux/compiler.h:77:42: note: in definition of macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c:626:16: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
WARN(true, "Corrupted pool %s", pool);
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:626:5: note: in expansion of macro 'WARN'
WARN(true, "Corrupted pool %s", pool);
^~~~
lib/genalloc.c:634:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Size provided differs from size "
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:633:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:635:31: note: format string is defined here
"measured from pool %s", pool);
~^
In file included from arch/x86/include/asm/bug.h:83:0,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/gfp.h:5,
from include/linux/slab.h:15,
from lib/genalloc.c:99:
lib/genalloc.c:643:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'struct gen_pool *' [-Wformat=]
"Unexpected bitmap collision while"
^
include/asm-generic/bug.h:98:50: note: in definition of macro '__WARN_printf'
#define __WARN_printf(arg...) do { __warn_printk(arg); __WARN(); } while (0)
^~~
lib/genalloc.c:642:5: note: in expansion of macro 'WARN'
WARN(true,
^~~~
lib/genalloc.c:644:36: note: format string is defined here
" freeing memory in pool %s", pool);
~^
cc1: some warnings being treated as errors
vim +624 lib/genalloc.c
929f9727 Dean Nelson 2006-06-23 609
7f184275 Huang Ying 2011-07-13 610 rcu_read_lock();
7f184275 Huang Ying 2011-07-13 611 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
674470d9 Joonyoung Shim 2013-09-11 612 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
3406f868 Igor Stoppa 2018-02-28 613 if (unlikely(addr + size - 1 > chunk->end_addr)) {
7f184275 Huang Ying 2011-07-13 614 rcu_read_unlock();
3406f868 Igor Stoppa 2018-02-28 615 WARN(true,
3406f868 Igor Stoppa 2018-02-28 616 "Trying to free unallocated memory"
3406f868 Igor Stoppa 2018-02-28 617 " from pool %s", pool);
7f184275 Huang Ying 2011-07-13 618 return;
f14f75b8 Jes Sorensen 2005-06-21 619 }
3406f868 Igor Stoppa 2018-02-28 620 start_entry = (addr - chunk->start_addr) >> order;
3406f868 Igor Stoppa 2018-02-28 621 remaining_entries = (chunk->end_addr - addr) >> order;
3406f868 Igor Stoppa 2018-02-28 622 boundary = get_boundary(chunk->entries, start_entry,
3406f868 Igor Stoppa 2018-02-28 623 remaining_entries);
3406f868 Igor Stoppa 2018-02-28 @624 if (unlikely(exit_test(boundary < 0))) {
3406f868 Igor Stoppa 2018-02-28 625 rcu_read_unlock();
3406f868 Igor Stoppa 2018-02-28 626 WARN(true, "Corrupted pool %s", pool);
3406f868 Igor Stoppa 2018-02-28 627 return;
f14f75b8 Jes Sorensen 2005-06-21 628 }
3406f868 Igor Stoppa 2018-02-28 629 nentries = boundary - start_entry;
3406f868 Igor Stoppa 2018-02-28 630 if (unlikely(size && (nentries !=
3406f868 Igor Stoppa 2018-02-28 631 mem_to_units(size, order)))) {
7f184275 Huang Ying 2011-07-13 632 rcu_read_unlock();
3406f868 Igor Stoppa 2018-02-28 633 WARN(true,
3406f868 Igor Stoppa 2018-02-28 634 "Size provided differs from size "
3406f868 Igor Stoppa 2018-02-28 635 "measured from pool %s", pool);
3406f868 Igor Stoppa 2018-02-28 636 return;
3406f868 Igor Stoppa 2018-02-28 637 }
3406f868 Igor Stoppa 2018-02-28 638 remain = alter_bitmap_ll(CLEAR_BITS, chunk->entries,
3406f868 Igor Stoppa 2018-02-28 639 start_entry, nentries);
3406f868 Igor Stoppa 2018-02-28 640 if (unlikely(remain)) {
3406f868 Igor Stoppa 2018-02-28 641 rcu_read_unlock();
3406f868 Igor Stoppa 2018-02-28 642 WARN(true,
3406f868 Igor Stoppa 2018-02-28 643 "Unexpected bitmap collision while"
3406f868 Igor Stoppa 2018-02-28 644 " freeing memory in pool %s", pool);
3406f868 Igor Stoppa 2018-02-28 645 return;
3406f868 Igor Stoppa 2018-02-28 646 }
3406f868 Igor Stoppa 2018-02-28 647 atomic_long_add(nentries << order, &chunk->avail);
3406f868 Igor Stoppa 2018-02-28 648 rcu_read_unlock();
3406f868 Igor Stoppa 2018-02-28 649 return;
3406f868 Igor Stoppa 2018-02-28 650 }
3406f868 Igor Stoppa 2018-02-28 651 }
3406f868 Igor Stoppa 2018-02-28 652 rcu_read_unlock();
3406f868 Igor Stoppa 2018-02-28 653 WARN(true, "address not found in pool %s", pool->name);
f14f75b8 Jes Sorensen 2005-06-21 654 }
f14f75b8 Jes Sorensen 2005-06-21 655 EXPORT_SYMBOL(gen_pool_free);
7f184275 Huang Ying 2011-07-13 656
:::::: The code at line 624 was first introduced by commit
:::::: 3406f8684f722bb52edc94f65976585acb6382ce genalloc: track beginning of allocations
:::::: TO: Igor Stoppa <[email protected]>
:::::: CC: 0day robot <[email protected]>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
Hi Igor,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on next-20180223]
[cannot apply to linus/master mmotm/master char-misc/char-misc-testing v4.16-rc3 v4.16-rc2 v4.16-rc1 v4.16-rc3]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Igor-Stoppa/mm-security-ro-protection-for-dynamic-data/20180302-232215
config: arm-allmodconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=arm
All errors (new ones prefixed by >>):
mm/test_pmalloc.c: In function 'test_pmalloc':
>> mm/test_pmalloc.c:52:14: error: implicit declaration of function 'vmalloc'; did you mean 'kvmalloc'? [-Werror=implicit-function-declaration]
var_vmall = vmalloc(SIZE_2);
^~~~~~~
kvmalloc
mm/test_pmalloc.c:52:12: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
var_vmall = vmalloc(SIZE_2);
^
>> mm/test_pmalloc.c:64:2: error: implicit declaration of function 'vfree'; did you mean 'kvfree'? [-Werror=implicit-function-declaration]
vfree(var_vmall);
^~~~~
kvfree
cc1: some warnings being treated as errors
vim +52 mm/test_pmalloc.c
27
28 #define is_alloc_ok(variable, size) \
29 validate_alloc(true, variable, size)
30
31 #define is_alloc_no(variable, size) \
32 validate_alloc(false, variable, size)
33
34 void test_pmalloc(void)
35 {
36 struct gen_pool *pool_unprot;
37 struct gen_pool *pool_prot;
38 void *var_prot, *var_unprot, *var_vmall;
39
40 pr_notice("pmalloc-selftest");
41 pool_unprot = pmalloc_create_pool("unprotected", 0);
42 if (unlikely(!pool_unprot))
43 goto error;
44 pool_prot = pmalloc_create_pool("protected", 0);
45 if (unlikely(!(pool_prot)))
46 goto error_release;
47
48 pr_notice("Testing allocation capability");
49 var_unprot = pmalloc(pool_unprot, SIZE_1 - 1, GFP_KERNEL);
50 var_prot = pmalloc(pool_prot, SIZE_1, GFP_KERNEL);
51 *(int *)var_prot = 0;
> 52 var_vmall = vmalloc(SIZE_2);
53
54
55 pr_notice("Test correctness of is_pmalloc_object()");
56 WARN_ON(unlikely(!is_alloc_ok(var_unprot, 10)));
57 WARN_ON(unlikely(!is_alloc_ok(var_unprot, SIZE_1)));
58 WARN_ON(unlikely(!is_alloc_ok(var_unprot, PAGE_SIZE)));
59 WARN_ON(unlikely(!is_alloc_no(var_unprot, SIZE_1 + 1)));
60 WARN_ON(unlikely(!is_alloc_no(var_vmall, 10)));
61
62
63 pfree(pool_unprot, var_unprot);
> 64 vfree(var_vmall);
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
.
.
On 2/28/18 12:06 PM, Igor Stoppa wrote:
> +
> +/**
> + * gen_pool_dma_alloc() - allocate special memory from the pool for DMA usage
> + * @pool: pool to allocate from
> + * @size: number of bytes to allocate from the pool
> + * @dma: dma-view physical address return value. Use NULL if unneeded.
> + *
> + * Allocate the requested number of bytes from the specified pool.
> + * Uses the pool allocation function (with first-fit algorithm by default).
> + * Can not be used in NMI handler on architectures without
> + * NMI-safe cmpxchg implementation.
> + *
> + * Return:
> + * * address of the memory allocated - success
> + * * NULL - error
> + */
> +void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma);
> +
OK, so gen_pool_dma_alloc() is defined here, which believe is the API
line being drawn for this series.
so,
.
.
.
>
>
> /**
> - * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
> + * gen_pool_dma_alloc() - allocate special memory from the pool for DMA usage
> * @pool: pool to allocate from
> * @size: number of bytes to allocate from the pool
> * @dma: dma-view physical address return value. Use NULL if unneeded.
> @@ -342,14 +566,15 @@ EXPORT_SYMBOL(gen_pool_alloc_algo);
> * Uses the pool allocation function (with first-fit algorithm by default).
> * Can not be used in NMI handler on architectures without
> * NMI-safe cmpxchg implementation.
> + *
> + * Return:
> + * * address of the memory allocated - success
> + * * NULL - error
> */
> void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
> {
> unsigned long vaddr;
>
> - if (!pool)
> - return NULL;
> -
why is this being removed? I don't believe this code was getting
removed from your v17 series patches.
> vaddr = gen_pool_alloc(pool, size);
> if (!vaddr)
> return NULL;
> @@ -362,10 +587,10 @@ void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
> EXPORT_SYMBOL(gen_pool_dma_alloc);
>
>
Otherwise, looks good,
Reviewed-by: Jay Freyensee <[email protected]>
> +
> +/*
> + * In case of failure of any of these tests, memory corruption is almost
> + * guarranteed; allowing the boot to continue means risking to corrupt
> + * also any filesystem/block device accessed write mode.
> + * Therefore, BUG_ON() is used, when testing.
> + */
> +
> +
I like the explanation; good background info on why something is
implemented the way it is :-).
Reviewed-by: Jay Freyensee <[email protected]>
Reviewed-by: Jay Freyensee <[email protected]>
On 2/28/18 12:06 PM, Igor Stoppa wrote:
> When a page is used for virtual memory, it is often necessary to obtain
> a handler to the corresponding vm_struct, which refers to the virtually
> continuous area generated when invoking vmalloc.
>
> The struct page has a "mapping" field, which can be re-used, to store a
> pointer to the parent area.
>
> This will avoid more expensive searches, later on.
>
> Signed-off-by: Igor Stoppa <[email protected]>
> ---
> include/linux/mm_types.h | 1 +
> mm/vmalloc.c | 2 ++
> 2 files changed, 3 insertions(+)
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index fd1af6b9591d..c3a4825e10c0 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -84,6 +84,7 @@ struct page {
> void *s_mem; /* slab first object */
> atomic_t compound_mapcount; /* first tail page */
> /* page_deferred_list().next -- second tail page */
> + struct vm_struct *area;
> };
>
> /* Second double word */
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index ebff729cc956..61a1ca22b0f6 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1536,6 +1536,7 @@ static void __vunmap(const void *addr, int deallocate_pages)
> struct page *page = area->pages[i];
>
> BUG_ON(!page);
> + page->area = NULL;
> __free_pages(page, 0);
> }
>
> @@ -1705,6 +1706,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
> area->nr_pages = i;
> goto fail;
> }
> + page->area = area;
> area->pages[i] = page;
> if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
> cond_resched();
snip
.
.
.
> +
> +config PROTECTABLE_MEMORY
> + bool
> + depends on MMU
Curious, would you also want to depend on "SECURITY" as well, as this is
being advertised as a compliment to __read_only_after_init, per the file
header comments, as I'm assuming ro_after_init would be disabled if the
SECURITY Kconfig selection is *NOT* selected?
> + depends on ARCH_HAS_SET_MEMORY
> + select GENERIC_ALLOCATOR
> + default y
> diff --git a/mm/Makefile b/mm/Makefile
> index e669f02c5a54..959fdbdac118 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -65,6 +65,7 @@ obj-$(CONFIG_SPARSEMEM) += sparse.o
> obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
> obj-$(CONFIG_SLOB) += slob.o
> obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
> +obj-$(CONFIG_PROTECTABLE_MEMORY) += pmalloc.o
> obj-$(CONFIG_KSM) += ksm.o
> obj-$(CONFIG_PAGE_POISONING) += page_poison.o
> obj-$(CONFIG_SLAB) += slab.o
> diff --git a/mm/pmalloc.c b/mm/pmalloc.c
> new file mode 100644
> index 000000000000..acdec0fbdde6
> --- /dev/null
> +++ b/mm/pmalloc.c
> @@ -0,0 +1,468 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * pmalloc.c: Protectable Memory Allocator
> + *
> + * (C) Copyright 2017 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa<[email protected]>
> + */
> +
> +#include <linux/printk.h>
> +#include <linux/init.h>
> +#include <linux/mm.h>
> +#include <linux/vmalloc.h>
> +#include <linux/genalloc.h>
> +#include <linux/kernel.h>
> +#include <linux/log2.h>
> +#include <linux/slab.h>
> +#include <linux/device.h>
> +#include <linux/atomic.h>
> +#include <linux/rculist.h>
> +#include <linux/set_memory.h>
> +#include <linux/bug.h>
> +#include <asm/cacheflush.h>
> +#include <asm/page.h>
> +
> +#include <linux/pmalloc.h>
> +/*
> + * pmalloc_data contains the data specific to a pmalloc pool,
> + * in a format compatible with the design of gen_alloc.
> + * Some of the fields are used for exposing the corresponding parameter
> + * to userspace, through sysfs.
> + */
> +struct pmalloc_data {
> + struct gen_pool *pool; /* Link back to the associated pool. */
> + bool protected; /* Status of the pool: RO or RW. */
nitpick, you could probably get a tad bit better byte packing alignment
of this struct if "bool protected" was stuck as the last element in this
data structure.
> + struct kobj_attribute attr_protected; /* Sysfs attribute. */
> + struct kobj_attribute attr_avail; /* Sysfs attribute. */
> + struct kobj_attribute attr_size; /* Sysfs attribute. */
> + struct kobj_attribute attr_chunks; /* Sysfs attribute. */
> + struct kobject *pool_kobject;
> + struct list_head node; /* list of pools */
> +};
> +
> +static LIST_HEAD(pmalloc_final_list);
> +static LIST_HEAD(pmalloc_tmp_list);
> +static struct list_head *pmalloc_list = &pmalloc_tmp_list;
> +static DEFINE_MUTEX(pmalloc_mutex);
> +static struct kobject *pmalloc_kobject;
> +
> +static ssize_t pmalloc_pool_show_protected(struct kobject *dev,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + struct pmalloc_data *data;
> +
> + data = container_of(attr, struct pmalloc_data, attr_protected);
> + if (data->protected)
> + return sprintf(buf, "protected\n");
> + else
> + return sprintf(buf, "unprotected\n");
> +}
> +
> +static ssize_t pmalloc_pool_show_avail(struct kobject *dev,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + struct pmalloc_data *data;
> +
> + data = container_of(attr, struct pmalloc_data, attr_avail);
> + return sprintf(buf, "%lu\n",
> + (unsigned long)gen_pool_avail(data->pool));
> +}
> +
> +static ssize_t pmalloc_pool_show_size(struct kobject *dev,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + struct pmalloc_data *data;
> +
> + data = container_of(attr, struct pmalloc_data, attr_size);
> + return sprintf(buf, "%lu\n",
> + (unsigned long)gen_pool_size(data->pool));
> +}
Curious, will this show the size in bytes?
> +
> +static void pool_chunk_number(struct gen_pool *pool,
> + struct gen_pool_chunk *chunk, void *data)
> +{
> + unsigned long *counter = data;
> +
> + (*counter)++;
> +}
> +
> +static ssize_t pmalloc_pool_show_chunks(struct kobject *dev,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + struct pmalloc_data *data;
> + unsigned long chunks_num = 0;
> +
> + data = container_of(attr, struct pmalloc_data, attr_chunks);
> + gen_pool_for_each_chunk(data->pool, pool_chunk_number, &chunks_num);
> + return sprintf(buf, "%lu\n", chunks_num);
> +}
> +
> +/* Exposes the pool and its attributes through sysfs. */
> +static struct kobject *pmalloc_connect(struct pmalloc_data *data)
> +{
> + const struct attribute *attrs[] = {
> + &data->attr_protected.attr,
> + &data->attr_avail.attr,
> + &data->attr_size.attr,
> + &data->attr_chunks.attr,
> + NULL
> + };
> + struct kobject *kobj;
> +
> + kobj = kobject_create_and_add(data->pool->name, pmalloc_kobject);
> + if (unlikely(!kobj))
> + return NULL;
> +
> + if (unlikely(sysfs_create_files(kobj, attrs) < 0)) {
> + kobject_put(kobj);
> + kobj = NULL;
> + }
> + return kobj;
> +}
> +
> +/* Removes the pool and its attributes from sysfs. */
> +static void pmalloc_disconnect(struct pmalloc_data *data,
> + struct kobject *kobj)
> +{
> + const struct attribute *attrs[] = {
> + &data->attr_protected.attr,
> + &data->attr_avail.attr,
> + &data->attr_size.attr,
> + &data->attr_chunks.attr,
> + NULL
> + };
> +
> + sysfs_remove_files(kobj, attrs);
> + kobject_put(kobj);
> +}
> +
> +/* Declares an attribute of the pool. */
> +#define pmalloc_attr_init(data, attr_name) \
> +do { \
> + sysfs_attr_init(&data->attr_##attr_name.attr); \
> + data->attr_##attr_name.attr.name = #attr_name; \
> + data->attr_##attr_name.attr.mode = VERIFY_OCTAL_PERMISSIONS(0400); \
> + data->attr_##attr_name.show = pmalloc_pool_show_##attr_name; \
Why are these ##attr's being used and not the #define macros already in
the kernel (DEVICE_ATTR(), DEVICE_ATTR_RO(), etc found in
/include/linux/device.h)? Those macros are much easier to read and use.
> +} while (0)
> +
> +struct gen_pool *pmalloc_create_pool(const char *name, int min_alloc_order)
> +{
> + struct gen_pool *pool;
> + const char *pool_name;
> + struct pmalloc_data *data;
> +
> + if (unlikely(!name)) {
> + WARN(true, "unnamed pool");
> + return NULL;
> + }
> +
> + if (min_alloc_order < 0)
> + min_alloc_order = ilog2(sizeof(unsigned long));
> +
> + pool = gen_pool_create(min_alloc_order, NUMA_NO_NODE);
> + if (unlikely(!pool))
> + return NULL;
> +
> + mutex_lock(&pmalloc_mutex);
> + list_for_each_entry(data, pmalloc_list, node)
> + if (!strcmp(name, data->pool->name))
> + goto same_name_err;
> +
> + pool_name = kstrdup(name, GFP_KERNEL);
> + if (unlikely(!pool_name))
> + goto name_alloc_err;
> +
> + data = kzalloc(sizeof(struct pmalloc_data), GFP_KERNEL);
> + if (unlikely(!data))
> + goto data_alloc_err;
> +
> + data->protected = false;
> + data->pool = pool;
> + pmalloc_attr_init(data, protected);
> + pmalloc_attr_init(data, avail);
> + pmalloc_attr_init(data, size);
> + pmalloc_attr_init(data, chunks);
> + pool->data = data;
> + pool->name = pool_name;
> +
> + list_add(&data->node, pmalloc_list);
> + if (pmalloc_list == &pmalloc_final_list)
> + data->pool_kobject = pmalloc_connect(data);
> + mutex_unlock(&pmalloc_mutex);
> + return pool;
> +
> +data_alloc_err:
> + kfree(pool_name);
> +name_alloc_err:
> +same_name_err:
> + mutex_unlock(&pmalloc_mutex);
> + gen_pool_destroy(pool);
> + return NULL;
> +}
> +
> +static inline bool chunk_tagging(void *chunk, bool tag)
> +{
> + struct vm_struct *area;
> + struct page *page;
> +
> + if (!is_vmalloc_addr(chunk))
> + return false;
> +
> + page = vmalloc_to_page(chunk);
> + if (unlikely(!page))
> + return false;
> +
> + area = page->area;
> + if (tag)
> + area->flags |= VM_PMALLOC;
> + else
> + area->flags &= ~VM_PMALLOC;
> + return true;
> +}
> +
> +
> +static inline bool tag_chunk(void *chunk)
> +{
> + return chunk_tagging(chunk, true);
> +}
> +
> +
> +static inline bool untag_chunk(void *chunk)
> +{
> + return chunk_tagging(chunk, false);
> +}
> +
> +enum {
> + INVALID_PMALLOC_OBJECT = -1,
> + NOT_PMALLOC_OBJECT = 0,
> + VALID_PMALLOC_OBJECT = 1,
> +};
> +
> +int is_pmalloc_object(const void *ptr, const unsigned long n)
> +{
> + struct vm_struct *area;
> + struct page *page;
> + unsigned long area_start;
> + unsigned long area_end;
> + unsigned long object_start;
> + unsigned long object_end;
> +
> +
> + /*
> + * is_pmalloc_object gets called pretty late, so chances are high
> + * that the object is indeed of vmalloc type
> + */
> + if (unlikely(!is_vmalloc_addr(ptr)))
> + return NOT_PMALLOC_OBJECT;
> +
> + page = vmalloc_to_page(ptr);
> + if (unlikely(!page))
> + return NOT_PMALLOC_OBJECT;
> +
> + area = page->area;
> +
> + if (likely(!(area->flags & VM_PMALLOC)))
> + return NOT_PMALLOC_OBJECT;
> +
> + area_start = (unsigned long)area->addr;
> + area_end = area_start + area->nr_pages * PAGE_SIZE - 1;
> + object_start = (unsigned long)ptr;
> + object_end = object_start + n - 1;
> +
> + if (likely((area_start <= object_start) &&
> + (object_end <= area_end)))
> + return VALID_PMALLOC_OBJECT;
> + else
> + return INVALID_PMALLOC_OBJECT;
> +}
> +
> +
> +bool pmalloc_prealloc(struct gen_pool *pool, size_t size)
> +{
> + void *chunk;
> + size_t chunk_size;
> + bool add_error;
> +
> + /* Expand pool */
> + chunk_size = roundup(size, PAGE_SIZE);
> + chunk = vmalloc(chunk_size);
> + if (unlikely(chunk == NULL))
> + return false;
> +
> + /* Locking is already done inside gen_pool_add */
> + add_error = gen_pool_add(pool, (unsigned long)chunk, chunk_size,
> + NUMA_NO_NODE);
> + if (unlikely(add_error != 0))
> + goto abort;
> +
> + return true;
> +abort:
> + vfree_atomic(chunk);
> + return false;
> +
> +}
> +
> +void *pmalloc(struct gen_pool *pool, size_t size, gfp_t gfp)
> +{
> + void *chunk;
> + size_t chunk_size;
> + bool add_error;
> + unsigned long retval;
> +
> + if (unlikely(((struct pmalloc_data *)(pool->data))->protected)) {
> + WARN(true, "pool %s is already protected", pool->name);
> + return NULL;
> + }
> +
> +retry_alloc_from_pool:
> + retval = gen_pool_alloc(pool, size);
> + if (retval)
> + goto return_allocation;
> +
> + if (unlikely((gfp & __GFP_ATOMIC))) {
> + if (unlikely((gfp & __GFP_NOFAIL)))
> + goto retry_alloc_from_pool;
> + else
> + return NULL;
> + }
> +
> + /* Expand pool */
> + chunk_size = roundup(size, PAGE_SIZE);
> + chunk = vmalloc(chunk_size);
> + if (unlikely(!chunk)) {
> + if (unlikely((gfp & __GFP_NOFAIL)))
> + goto retry_alloc_from_pool;
> + else
> + return NULL;
> + }
> + if (unlikely(!tag_chunk(chunk)))
> + goto free;
> +
> + /* Locking is already done inside gen_pool_add */
> + add_error = gen_pool_add(pool, (unsigned long)chunk, chunk_size,
> + NUMA_NO_NODE);
> + if (unlikely(add_error))
> + goto abort;
> +
> + retval = gen_pool_alloc(pool, size);
> + if (retval) {
> +return_allocation:
> + *(size_t *)retval = size;
> + if (gfp & __GFP_ZERO)
> + memset((void *)retval, 0, size);
> + return (void *)retval;
> + }
> + /*
> + * Here there is no test for __GFP_NO_FAIL because, in case of
> + * concurrent allocation, one thread might add a chunk to the
> + * pool and this memory could be allocated by another thread,
> + * before the first thread gets a chance to use it.
> + * As long as vmalloc succeeds, it's ok to retry.
> + */
> + goto retry_alloc_from_pool;
> +abort:
> + untag_chunk(chunk);
> +free:
> + vfree_atomic(chunk);
> + return NULL;
> +}
> +
> +static void pmalloc_chunk_set_protection(struct gen_pool *pool,
> + struct gen_pool_chunk *chunk,
> + void *data)
> +{
> + const bool *flag = data;
> + size_t chunk_size = chunk->end_addr + 1 - chunk->start_addr;
> + unsigned long pages = chunk_size / PAGE_SIZE;
> +
> + if (unlikely(chunk_size & (PAGE_SIZE - 1))) {
> + WARN(true, "Chunk size is not a multiple of PAGE_SIZE.");
> + return;
> + }
> +
> + if (*flag)
> + set_memory_ro(chunk->start_addr, pages);
> + else
> + set_memory_rw(chunk->start_addr, pages);
> +}
> +
> +static int pmalloc_pool_set_protection(struct gen_pool *pool, bool protection)
> +{
> + struct pmalloc_data *data;
> + struct gen_pool_chunk *chunk;
> +
> + data = pool->data;
> + if (unlikely(data->protected == protection)) {
> + WARN(true, "The pool %s is already protected as requested",
> + pool->name);
> + return 0;
> + }
> + data->protected = protection;
> + list_for_each_entry(chunk, &(pool)->chunks, next_chunk)
> + pmalloc_chunk_set_protection(pool, chunk, &protection);
> + return 0;
> +}
> +
> +int pmalloc_protect_pool(struct gen_pool *pool)
> +{
> + return pmalloc_pool_set_protection(pool, true);
> +}
> +
> +
> +static void pmalloc_chunk_free(struct gen_pool *pool,
> + struct gen_pool_chunk *chunk, void *data)
> +{
> + untag_chunk(chunk);
> + gen_pool_flush_chunk(pool, chunk);
> + vfree_atomic((void *)chunk->start_addr);
> +}
> +
> +
> +int pmalloc_destroy_pool(struct gen_pool *pool)
> +{
> + struct pmalloc_data *data;
> +
> + data = pool->data;
> +
> + mutex_lock(&pmalloc_mutex);
> + list_del(&data->node);
> + mutex_unlock(&pmalloc_mutex);
> +
> + if (likely(data->pool_kobject))
> + pmalloc_disconnect(data, data->pool_kobject);
> +
> + pmalloc_pool_set_protection(pool, false);
> + gen_pool_for_each_chunk(pool, pmalloc_chunk_free, NULL);
> + gen_pool_destroy(pool);
> + kfree(data);
> + return 0;
> +}
> +
> +/*
> + * When the sysfs is ready to receive registrations, connect all the
> + * pools previously created. Also enable further pools to be connected
> + * right away.
> + */
> +static int __init pmalloc_late_init(void)
> +{
> + struct pmalloc_data *data, *n;
> +
> + pmalloc_kobject = kobject_create_and_add("pmalloc", kernel_kobj);
> +
> + mutex_lock(&pmalloc_mutex);
> + pmalloc_list = &pmalloc_final_list;
> +
> + if (likely(pmalloc_kobject != NULL)) {
> + list_for_each_entry_safe(data, n, &pmalloc_tmp_list, node) {
> + list_move(&data->node, &pmalloc_final_list);
> + pmalloc_connect(data);
> + }
> + }
> + mutex_unlock(&pmalloc_mutex);
> + return 0;
I'd just go ahead and return a different value if pmalloc_kobject does
equal to NULL. __init is already returning a value, and the __init is
already checking an error case for failure, might as well go all the way
and stick a little icing on the cake and return a different (errno)
value for this case.
>
>
>
>
Thanks,
Jay
On Wed, Feb 28, 2018 at 10:06:14PM +0200, Igor Stoppa wrote:
> The genalloc library is only capable of tracking if a certain unit of
> allocation is in use or not.
>
> It is not capable of discerning where the memory associated to an
> allocation request begins and where it ends.
>
> The reason is that units of allocations are tracked by using a bitmap,
> where each bit represents that the unit is either allocated (1) or
> available (0).
>
> The user of the API must keep track of how much space was requested, if
> it ever needs to be freed.
>
> This can cause errors being undetected.
> Examples:
> * Only a subset of the memory provided to an allocation request is freed
> * The memory from a subsequent allocation is freed
> * The memory being freed doesn't start at the beginning of an
> allocation.
>
> The bitmap is used because it allows to perform lockless read/write
> access, where this is supported by hw through cmpxchg.
> Similarly, it is possible to scan the bitmap for a sufficiently long
> sequence of zeros, to identify zones available for allocation.
>
> This patch doubles the space reserved in the bitmap for each allocation,
> to track their beginning.
>
> For details, see the documentation inside lib/genalloc.c
>
> The primary effect of this patch is that code using the gen_alloc
> library does not need anymore to keep track of the size of the
> allocations it makes.
>
> Prior to this patch, it was necessary to keep track of the size of the
> allocation, so that it would be possible, later on, to know how much
> space should be freed.
>
> Now, users of the api can choose to etiher still specify explicitly the
> size, or let the library determine it, by giving a value of 0.
>
> However, even when the value is specified, the library still uses its on
> understanding of the space associated with a certain allocation, to
> confirm that they are consistent.
>
> This verification also confirms that the patch works correctly.
>
> Eventually, the extra parameter (and the corresponding verification)
> could be dropped, in favor of a simplified API.
>
> Signed-off-by: Igor Stoppa <[email protected]>
> ---
> include/linux/genalloc.h | 354 ++++++++++++++++++++---
> lib/genalloc.c | 721 ++++++++++++++++++++++++++++++++++-------------
> 2 files changed, 837 insertions(+), 238 deletions(-)
Thanks for taking time to update the kernel-doc parts!
Some docs related comments below.
> diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
> index 872f930f1b06..7b1a1f1d9985 100644
> --- a/include/linux/genalloc.h
> +++ b/include/linux/genalloc.h
> @@ -32,7 +32,7 @@
>
> #include <linux/types.h>
> #include <linux/spinlock_types.h>
> -#include <linux/atomic.h>
> +#include <linux/slab.h>
>
> struct device;
> struct device_node;
> @@ -76,7 +76,7 @@ struct gen_pool_chunk {
> phys_addr_t phys_addr; /* physical starting address of memory chunk */
> unsigned long start_addr; /* start address of memory chunk */
> unsigned long end_addr; /* end address of memory chunk (inclusive) */
> - unsigned long bits[0]; /* bitmap for allocating memory chunk */
> + unsigned long entries[0]; /* bitmap for allocating memory chunk */
> };
>
> /*
> @@ -93,10 +93,40 @@ struct genpool_data_fixed {
> unsigned long offset; /* The offset of the specific region */
> };
>
> -extern struct gen_pool *gen_pool_create(int, int);
> -extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
> -extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
> - size_t, int);
> +/**
> + * gen_pool_create() - create a new special memory pool
> + * @min_alloc_order: log base 2 of number of bytes each bitmap entry
> + * represents
> + * @nid: node id of the node the pool structure should be allocated on,
> + * or -1
> + *
> + * Create a new special memory pool that can be used to manage special
> + * purpose memory not managed by the regular kmalloc/kfree interface.
> + *
> + * Return:
> + * * pointer to the pool - success
> + * * NULL - otherwise
> + */
If I'm not mistaken, several kernel-doc descriptions are duplicated now.
Can you please keep a single copy? ;-)
> +struct gen_pool *gen_pool_create(int min_alloc_order, int nid);
> +
> +/**
> + * gen_pool_add_virt() - add a new chunk of special memory to the pool
> + * @pool: pool to add new memory chunk to
> + * @virt: virtual starting address of memory chunk to add to pool
> + * @phys: physical starting address of memory chunk to add to pool
> + * @size: size in bytes of the memory chunk to add to pool
> + * @nid: node id of the node the chunk structure and bitmap should be
> + * allocated on, or -1
> + *
> + * Add a new chunk of special memory to the specified pool.
> + *
> + * Return:
> + * * 0 - success
> + * * -ve errno - failure
> + */
> +int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt,
> + phys_addr_t phys, size_t size, int nid);
> +
> /**
> * gen_pool_add - add a new chunk of special memory to the pool
> * @pool: pool to add new memory chunk to
...
> diff --git a/lib/genalloc.c b/lib/genalloc.c
> index ca06adc4f445..d505b959f888 100644
> --- a/lib/genalloc.c
> +++ b/lib/genalloc.c
> @@ -26,6 +26,74 @@
> *
> * This source code is licensed under the GNU General Public License,
> * Version 2. See the file COPYING for more details.
> + *
> + *
> + *
> + * Encoding of the bitmap tracking the allocations
> + * -----------------------------------------------
> + *
> + * The bitmap is composed of units of allocations.
> + *
> + * Each unit of allocation is represented using 2 consecutive bits.
> + *
> + * This makes it possible to encode, for each unit of allocation,
> + * information about:
> + * - allocation status (busy/free)
> + * - beginning of a sequennce of allocation units (first / successive)
> + *
> + *
> + * Dictionary of allocation units (msb to the left, lsb to the right):
> + *
> + * 11: first allocation unit in the allocation
> + * 10: any subsequent allocation unit (if any) in the allocation
> + * 00: available allocation unit
> + * 01: invalid
> + *
> + * Example, using the same notation as above - MSb.......LSb:
> + *
> + * ...000010111100000010101011 <-- Read in this direction.
> + * \__|\__|\|\____|\______|
> + * | | | | \___ 4 used allocation units
> + * | | | \___________ 3 empty allocation units
> + * | | \_________________ 1 used allocation unit
> + * | \___________________ 2 used allocation units
> + * \_______________________ 2 empty allocation units
> + *
> + * The encoding allows for lockless operations, such as:
> + * - search for a sufficiently large range of allocation units
> + * - reservation of a selected range of allocation units
> + * - release of a specific allocation
> + *
> + * The alignment at which to perform the research for sequence of empty
^ search?
> + * allocation units (marked as zeros in the bitmap) is 2^1.
> + *
> + * This means that an allocation can start only at even places
> + * (bit 0, bit 2, etc.) in the bitmap.
> + *
> + * Therefore, the number of zeroes to look for must be twice the number
> + * of desired allocation units.
> + *
> + * When it's time to free the memory associated to an allocation request,
> + * it's a matter of checking if the corresponding allocation unit is
> + * really the beginning of an allocation (both bits are set to 1).
> + *
> + * Looking for the ending can also be performed locklessly.
> + * It's sufficient to identify the first mapped allocation unit
> + * that is represented either as free (00) or busy (11).
> + * Even if the allocation status should change in the meanwhile, it
> + * doesn't matter, since it can only transition between free (00) and
> + * first-allocated (11).
> + *
> + * The parameter indicating to the *_free() function the size of the
> + * space that should be freed can be either set to 0, for automated
> + * assessment, or it can be specified explicitly.
> + *
> + * In case it is specified explicitly, the value is verified agaisnt what
> + * the library is tracking internally.
> + *
> + * If ever needed, the bitmap could be extended, assigning larger amounts
> + * of bits to each allocation unit (the increase must follow powers of 2),
> + * to track other properties of the allocations.
> */
>
> #include <linux/slab.h>
...
> -/*
> - * bitmap_set_ll - set the specified number of bits at the specified position
> +
> +/**
> + * get_boundary() - verifies address, then measure length.
There's some lack of consistency between the name and implementation and
the description.
It seems that it would be simpler to actually make it get_length() and
return the length of the allocation or nentries if the latter is smaller.
Then in gen_pool_free() there will be no need to recalculate nentries
again.
> * @map: pointer to a bitmap
> - * @start: a bit position in @map
> - * @nr: number of bits to set
> + * @start_entry: the index of the first entry in the bitmap
> + * @nentries: number of entries to alter
Maybe: "maximal number of entries to check"?
> *
> - * Set @nr bits start from @start in @map lock-lessly. Several users
> - * can set/clear the same bitmap simultaneously without lock. If two
> - * users set the same bit, one user will return remain bits, otherwise
> - * return 0.
> + * Return:
> + * * length of an allocation - success
> + * * -EINVAL - invalid parameters
> */
> -static int bitmap_set_ll(unsigned long *map, int start, int nr)
> +static int get_boundary(unsigned long *map, unsigned int start_entry,
> + unsigned int nentries)
> {
> - unsigned long *p = map + BIT_WORD(start);
> - const int size = start + nr;
> - int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
> - unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
> -
> - while (nr - bits_to_set >= 0) {
> - if (set_bits_ll(p, mask_to_set))
> - return nr;
> - nr -= bits_to_set;
> - bits_to_set = BITS_PER_LONG;
> - mask_to_set = ~0UL;
> - p++;
> - }
> - if (nr) {
> - mask_to_set &= BITMAP_LAST_WORD_MASK(size);
> - if (set_bits_ll(p, mask_to_set))
> - return nr;
> - }
> + int i;
> + unsigned long bitmap_entry;
>
> - return 0;
> +
> + if (unlikely(get_bitmap_entry(map, start_entry) != ENTRY_HEAD))
> + return -EINVAL;
> + for (i = start_entry + 1; i < nentries; i++) {
> + bitmap_entry = get_bitmap_entry(map, i);
> + if (bitmap_entry == ENTRY_HEAD ||
> + bitmap_entry == ENTRY_UNUSED)
> + return i;
> + }
> + return nentries - start_entry;
Shouldn't it be "nentries + start_entry"?
> }
...
> @@ -275,7 +492,7 @@ unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
> EXPORT_SYMBOL(gen_pool_alloc);
>
> /**
> - * gen_pool_alloc_algo - allocate special memory from the pool
> + * gen_pool_alloc_algo() - allocate special memory from the pool
+ using specified algorithm
> * @pool: pool to allocate from
> * @size: number of bytes to allocate from the pool
> * @algo: algorithm passed from caller
> @@ -285,14 +502,18 @@ EXPORT_SYMBOL(gen_pool_alloc);
> * Uses the pool allocation function (with first-fit algorithm by default).
"uses the provided @algo function to find room for the allocation"
> * Can not be used in NMI handler on architectures without
> * NMI-safe cmpxchg implementation.
> + *
> + * Return:
> + * * address of the memory allocated - success
> + * * NULL - error
> */
> unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
> genpool_algo_t algo, void *data)
> {
> struct gen_pool_chunk *chunk;
> unsigned long addr = 0;
> - int order = pool->min_alloc_order;
> - int nbits, start_bit, end_bit, remain;
> + unsigned int order = pool->min_alloc_order;
> + unsigned int nentries, start_entry, end_entry, remain;
>
> #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
> BUG_ON(in_nmi());
> @@ -301,29 +522,32 @@ unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
> if (size == 0)
> return 0;
>
> - nbits = (size + (1UL << order) - 1) >> order;
> + nentries = mem_to_units(size, order);
> rcu_read_lock();
> list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
> if (size > atomic_long_read(&chunk->avail))
> continue;
>
> - start_bit = 0;
> - end_bit = chunk_size(chunk) >> order;
> + start_entry = 0;
> + end_entry = chunk_size(chunk) >> order;
> retry:
> - start_bit = algo(chunk->bits, end_bit, start_bit,
> - nbits, data, pool);
> - if (start_bit >= end_bit)
> + start_entry = algo(chunk->entries, end_entry, start_entry,
> + nentries, data, pool);
> + if (start_entry >= end_entry)
> continue;
> - remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
> + remain = alter_bitmap_ll(SET_BITS, chunk->entries,
> + start_entry, nentries);
> if (remain) {
> - remain = bitmap_clear_ll(chunk->bits, start_bit,
> - nbits - remain);
> - BUG_ON(remain);
> + remain = alter_bitmap_ll(CLEAR_BITS,
> + chunk->entries,
> + start_entry,
> + nentries - remain);
> goto retry;
> }
>
> - addr = chunk->start_addr + ((unsigned long)start_bit << order);
> - size = nbits << order;
> + addr = chunk->start_addr +
> + ((unsigned long)start_entry << order);
> + size = nentries << order;
> atomic_long_sub(size, &chunk->avail);
> break;
> }
...
> @@ -738,17 +1065,19 @@ EXPORT_SYMBOL(devm_gen_pool_create);
>
> #ifdef CONFIG_OF
> /**
> - * of_gen_pool_get - find a pool by phandle property
> + * of_gen_pool_get() - find a pool by phandle property
> * @np: device node
> * @propname: property name containing phandle(s)
> * @index: index into the phandle array
> *
> - * Returns the pool that contains the chunk starting at the physical
> - * address of the device tree node pointed at by the phandle property,
> - * or NULL if not found.
> + * Return:
> + * * pool address - it contains the chunk starting at the physical
> + * address of the device tree node pointed at by
> + * the phandle property
> + * * NULL - otherwise
> */
> struct gen_pool *of_gen_pool_get(struct device_node *np,
> - const char *propname, int index)
> + const char *propname, int index)
> {
> struct platform_device *pdev;
> struct device_node *np_pool, *parent;
> --
> 2.14.1
>
--
Sincerely yours,
Mike.
On Wed, Feb 28, 2018 at 10:06:20PM +0200, Igor Stoppa wrote:
> Detailed documentation about the protectable memory allocator.
>
> Signed-off-by: Igor Stoppa <[email protected]>
> ---
> Documentation/core-api/index.rst | 1 +
> Documentation/core-api/pmalloc.rst | 111 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 112 insertions(+)
> create mode 100644 Documentation/core-api/pmalloc.rst
>
> diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst
> index c670a8031786..8f5de42d6571 100644
> --- a/Documentation/core-api/index.rst
> +++ b/Documentation/core-api/index.rst
> @@ -25,6 +25,7 @@ Core utilities
> genalloc
> errseq
> printk-formats
> + pmalloc
>
> Interfaces for kernel debugging
> ===============================
> diff --git a/Documentation/core-api/pmalloc.rst b/Documentation/core-api/pmalloc.rst
> new file mode 100644
> index 000000000000..8fb9c9d3171b
> --- /dev/null
> +++ b/Documentation/core-api/pmalloc.rst
> @@ -0,0 +1,111 @@
> +.. SPDX-License-Identifier: GPL-2.0
Please add a label to allow cross-referencing
> +
> +Protectable memory allocator
> +============================
> +
> +Purpose
> +-------
> +
> +The pmalloc library is meant to provide R/O status to data that, for some
> +reason, could neither be declared as constant, nor could it take advantage
> +of the qualifier __ro_after_init, but is write-once and read-only in spirit.
> +It protects data from both accidental and malicious overwrites.
> +
> +Example: A policy that is loaded from userspace.
> +
> +
> +Concept
> +-------
> +
> +pmalloc builds on top of genalloc, using the same concept of memory pools.
It would be nice to add a label to genalloc.rst and reference it here:
diff --git a/Documentation/core-api/genalloc.rst b/Documentation/core-api/genalloc.rst
index 6b38a39fab24..983fa94f999c 100644
--- a/Documentation/core-api/genalloc.rst
+++ b/Documentation/core-api/genalloc.rst
@@ -1,3 +1,5 @@
+.. _genalloc:
+
The genalloc/genpool subsystem
==============================
> +
> +The value added by pmalloc is that now the memory contained in a pool can
> +become R/O, for the rest of the life of the pool.
> +
IMHO, "read only" looks better than R/O
> +Different kernel drivers and threads can use different pools, for finer
> +control of what becomes R/O and when. And for improved lockless concurrency.
> +
> +
> +Caveats
> +-------
> +
> +- Memory freed while a pool is not yet protected will be reused.
> +
> +- Once a pool is protected, it's not possible to allocate any more memory
> + from it.
> +
> +- Memory "freed" from a protected pool indicates that such memory is not
> + in use anymore by the requester; however, it will not become available
> + for further use, until the pool is destroyed.
> +
> +- pmalloc does not provide locking support with respect to allocating vs
> + protecting an individual pool, for performance reasons.
> + It is recommended not to share the same pool between unrelated functions.
> + Should sharing be a necessity, the user of the shared pool is expected
> + to implement locking for that pool.
> +
> +- pmalloc uses genalloc to optimize the use of the space it allocates
> + through vmalloc. Some more TLB entries will be used, however less than
> + in the case of using vmalloc directly. The exact number depends on the
> + size of each allocation request and possible slack.
> +
> +- Considering that not much data is supposed to be dynamically allocated
> + and then marked as read-only, it shouldn't be an issue that the address
> + range for pmalloc is limited, on 32-bit systems.
> +
> +- Regarding SMP systems, the allocations are expected to happen mostly
> + during an initial transient, after which there should be no more need to
> + perform cross-processor synchronizations of page tables.
> +
> +- To facilitate the conversion of existing code to pmalloc pools, several
> + helper functions are provided, mirroring their kmalloc counterparts.
> +
> +
> +Use
> +---
> +
> +The typical sequence, when using pmalloc, is:
> +
> +1. create a pool
Can we use #. instead of numbers for the numbered list items?
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc_create_pool
> +
> +2. [optional] pre-allocate some memory in the pool
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc_prealloc
Maybe it's better to have a short reference to the function and keep all
the elaborate descriptions in the API section?
For instance, something like
diff --git a/Documentation/core-api/pmalloc.rst b/Documentation/core-api/pmalloc.rst
@@ -68,8 +70,7 @@ The typical sequence, when using pmalloc, is:
1. create a pool
-.. kernel-doc:: include/linux/pmalloc.h
- :functions: pmalloc_create_pool
+ :c:func:`pmalloc_create_pool`
> +3. issue one or more allocation requests to the pool with locking as needed
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pzalloc
> +
> +4. initialize the memory obtained with desired values
> +
> +5. [optional] iterate over points 3 & 4 as needed
> +
> +6. write-protect the pool
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc_protect_pool
> +
> +7. use in read-only mode the handles obtained through the allocations
> +
> +8. [optional] release all the memory allocated
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pfree
> +
> +9. [optional, but depends on point 8] destroy the pool
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc_destroy_pool
> +
> +API
> +---
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> --
> 2.14.1
>
--
Sincerely yours,
Mike.
On Wed, Feb 28, 2018 at 10:06:14PM +0200, Igor Stoppa wrote:
> + * Encoding of the bitmap tracking the allocations
> + * -----------------------------------------------
> + *
> + * The bitmap is composed of units of allocations.
> + *
> + * Each unit of allocation is represented using 2 consecutive bits.
> + *
> + * This makes it possible to encode, for each unit of allocation,
> + * information about:
> + * - allocation status (busy/free)
> + * - beginning of a sequennce of allocation units (first / successive)
> + *
> + *
> + * Dictionary of allocation units (msb to the left, lsb to the right):
> + *
> + * 11: first allocation unit in the allocation
> + * 10: any subsequent allocation unit (if any) in the allocation
> + * 00: available allocation unit
> + * 01: invalid
> + *
> + * Example, using the same notation as above - MSb.......LSb:
> + *
> + * ...000010111100000010101011 <-- Read in this direction.
> + * \__|\__|\|\____|\______|
> + * | | | | \___ 4 used allocation units
> + * | | | \___________ 3 empty allocation units
> + * | | \_________________ 1 used allocation unit
> + * | \___________________ 2 used allocation units
> + * \_______________________ 2 empty allocation units
> + *
> + * The encoding allows for lockless operations, such as:
> + * - search for a sufficiently large range of allocation units
> + * - reservation of a selected range of allocation units
> + * - release of a specific allocation
> + *
> + * The alignment at which to perform the research for sequence of empty
> + * allocation units (marked as zeros in the bitmap) is 2^1.
> + *
> + * This means that an allocation can start only at even places
> + * (bit 0, bit 2, etc.) in the bitmap.
> + *
> + * Therefore, the number of zeroes to look for must be twice the number
> + * of desired allocation units.
> + *
> + * When it's time to free the memory associated to an allocation request,
> + * it's a matter of checking if the corresponding allocation unit is
> + * really the beginning of an allocation (both bits are set to 1).
> + *
> + * Looking for the ending can also be performed locklessly.
> + * It's sufficient to identify the first mapped allocation unit
> + * that is represented either as free (00) or busy (11).
> + * Even if the allocation status should change in the meanwhile, it
> + * doesn't matter, since it can only transition between free (00) and
> + * first-allocated (11).
This seems unnecessarily complicated. Why not handle it like this:
- Double the bitmap in size (as you have done) but
- The first half of the bits are unchanged from the existing implementation
- The second half of the bits are used for determining the length
On allocation, you look for a sufficiently-large string of 0 bits in
the first-half. When you find it, you set all of them to 1, and set one
bit in the second-half to indicate where the tail of the allocation is
(you might actually want to use an rbtree or something to handle this ...
using all these bits seems pretty inefficient).
On Tue, Mar 06, 2018 at 02:19:03PM +0100, Mike Rapoport wrote:
> > +/**
> > + * gen_pool_create() - create a new special memory pool
> > + * @min_alloc_order: log base 2 of number of bytes each bitmap entry
> > + * represents
> > + * @nid: node id of the node the pool structure should be allocated on,
> > + * or -1
> > + *
> > + * Create a new special memory pool that can be used to manage special
> > + * purpose memory not managed by the regular kmalloc/kfree interface.
> > + *
> > + * Return:
> > + * * pointer to the pool - success
> > + * * NULL - otherwise
> > + */
>
> If I'm not mistaken, several kernel-doc descriptions are duplicated now.
> Can you please keep a single copy? ;-)
I think the problem is that Igor has chosen to put the kernel-doc with
the function declaration. I think we usually recommend putting it with
the definition so it's more likely to be updated.
On 06/03/2018 16:10, Matthew Wilcox wrote:
> On Wed, Feb 28, 2018 at 10:06:14PM +0200, Igor Stoppa wrote:
>> + * Encoding of the bitmap tracking the allocations
>> + * -----------------------------------------------
>> + *
>> + * The bitmap is composed of units of allocations.
>> + *
>> + * Each unit of allocation is represented using 2 consecutive bits.
>> + *
>> + * This makes it possible to encode, for each unit of allocation,
>> + * information about:
>> + * - allocation status (busy/free)
>> + * - beginning of a sequennce of allocation units (first / successive)
>> + *
>> + *
>> + * Dictionary of allocation units (msb to the left, lsb to the right):
>> + *
>> + * 11: first allocation unit in the allocation
>> + * 10: any subsequent allocation unit (if any) in the allocation
>> + * 00: available allocation unit
>> + * 01: invalid
>> + *
>> + * Example, using the same notation as above - MSb.......LSb:
>> + *
>> + * ...000010111100000010101011 <-- Read in this direction.
>> + * \__|\__|\|\____|\______|
>> + * | | | | \___ 4 used allocation units
>> + * | | | \___________ 3 empty allocation units
>> + * | | \_________________ 1 used allocation unit
>> + * | \___________________ 2 used allocation units
>> + * \_______________________ 2 empty allocation units
>> + *
>> + * The encoding allows for lockless operations, such as:
>> + * - search for a sufficiently large range of allocation units
>> + * - reservation of a selected range of allocation units
>> + * - release of a specific allocation
>> + *
>> + * The alignment at which to perform the research for sequence of empty
>> + * allocation units (marked as zeros in the bitmap) is 2^1.
>> + *
>> + * This means that an allocation can start only at even places
>> + * (bit 0, bit 2, etc.) in the bitmap.
>> + *
>> + * Therefore, the number of zeroes to look for must be twice the number
>> + * of desired allocation units.
>> + *
>> + * When it's time to free the memory associated to an allocation request,
>> + * it's a matter of checking if the corresponding allocation unit is
>> + * really the beginning of an allocation (both bits are set to 1).
>> + *
>> + * Looking for the ending can also be performed locklessly.
>> + * It's sufficient to identify the first mapped allocation unit
>> + * that is represented either as free (00) or busy (11).
>> + * Even if the allocation status should change in the meanwhile, it
>> + * doesn't matter, since it can only transition between free (00) and
>> + * first-allocated (11).
>
> This seems unnecessarily complicated.
TBH it seemed to me a natural extension of the existing encoding :-)
> Why not handle it like this:
>
> - Double the bitmap in size (as you have done) but
> - The first half of the bits are unchanged from the existing implementation
> - The second half of the bits are used for determining the length
Wouldn't that mean a less tight loop and less localized data?
The implementation from this patch does not have to jump elsewhere, when
(un)marking the allocation units and the start.
> On allocation, you look for a sufficiently-large string of 0 bits in
> the first-half. When you find it, you set all of them to 1, and set one
> bit in the second-half to indicate where the tail of the allocation is
> (you might actually want to use an rbtree or something to handle this ...
> using all these bits seems pretty inefficient).
1 bit maps to 1 unit of allocation, which is very seldom 1 byte.
For pmalloc use, I expect that the average allocation is likely to be
2-4 units, where 1 unit equals either a 32 or 64 bits word.
So it's probably likely that for every couple of allocation units, one
is marked as start-of-allocation.
In other cases where genalloc is used, like the tracking of uncached
pages, 1 unit of allocation equals to 1 page.
I would expect the rbtree to end up generating a far larger footprint.
For the same reasons, since the bitmap is implemented using unsigned
longs, chances are high that one allocation will fit in one bitmap
"word", which means that if the "beginning" bit and the "occupied" bit
are adjacent, one write is sufficient.
In the case you describe, it would be almost always at least 2.
I do not have factual evidence to back my reasoning, but it seems more
likely to be the case, from my analysis of data types that could belong
to pools (both existing users of genalloc and my experiments with
SELinux data structures and pmalloc).
Even in the XFS case, if I understood correctly, it was about protecting
1 or 2 pages at a time, which seems to fit what I have empirically observed.
What makes you think otherwise?
--
igor
Looks good, and a bit more thorough test than last iteration.
Reviewed-by: Jay Freyensee <[email protected]>
On 2/28/18 12:06 PM, Igor Stoppa wrote:
> Add basic self-test functionality for pmalloc.
>
> The testing is introduced as early as possible, right after the main
> dependency, genalloc, has passed successfully, so that it can help
> diagnosing failures in pmalloc users.
>
> Signed-off-by: Igor Stoppa <[email protected]>
> ---
> include/linux/test_pmalloc.h | 24 +++++++++++
> init/main.c | 2 +
> mm/Kconfig | 10 +++++
> mm/Makefile | 1 +
> mm/test_pmalloc.c | 100 +++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 137 insertions(+)
> create mode 100644 include/linux/test_pmalloc.h
> create mode 100644 mm/test_pmalloc.c
>
> diff --git a/include/linux/test_pmalloc.h b/include/linux/test_pmalloc.h
> new file mode 100644
> index 000000000000..c7e2e451c17c
> --- /dev/null
> +++ b/include/linux/test_pmalloc.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * test_pmalloc.h
> + *
> + * (C) Copyright 2018 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <[email protected]>
> + */
> +
> +
> +#ifndef __LINUX_TEST_PMALLOC_H
> +#define __LINUX_TEST_PMALLOC_H
> +
> +
> +#ifdef CONFIG_TEST_PROTECTABLE_MEMORY
> +
> +void test_pmalloc(void);
> +
> +#else
> +
> +static inline void test_pmalloc(void){};
> +
> +#endif
> +
> +#endif
> diff --git a/init/main.c b/init/main.c
> index 2bf1312fd2fe..ea44c940070a 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -91,6 +91,7 @@
> #include <linux/rodata_test.h>
> #include <linux/jump_label.h>
> #include <linux/test_genalloc.h>
> +#include <linux/test_pmalloc.h>
>
> #include <asm/io.h>
> #include <asm/bugs.h>
> @@ -663,6 +664,7 @@ asmlinkage __visible void __init start_kernel(void)
> mem_encrypt_init();
>
> test_genalloc();
> + test_pmalloc();
> #ifdef CONFIG_BLK_DEV_INITRD
> if (initrd_start && !initrd_below_start_ok &&
> page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 016d29b9400b..47b0843b02d2 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -767,3 +767,13 @@ config PROTECTABLE_MEMORY
> depends on ARCH_HAS_SET_MEMORY
> select GENERIC_ALLOCATOR
> default y
> +
> +config TEST_PROTECTABLE_MEMORY
> + bool "Run self test for pmalloc memory allocator"
> + depends on MMU
> + depends on ARCH_HAS_SET_MEMORY
> + select PROTECTABLE_MEMORY
> + default n
> + help
> + Tries to verify that pmalloc works correctly and that the memory
> + is effectively protected.
> diff --git a/mm/Makefile b/mm/Makefile
> index 959fdbdac118..1de4be5fd0bc 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -66,6 +66,7 @@ obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
> obj-$(CONFIG_SLOB) += slob.o
> obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
> obj-$(CONFIG_PROTECTABLE_MEMORY) += pmalloc.o
> +obj-$(CONFIG_TEST_PROTECTABLE_MEMORY) += test_pmalloc.o
> obj-$(CONFIG_KSM) += ksm.o
> obj-$(CONFIG_PAGE_POISONING) += page_poison.o
> obj-$(CONFIG_SLAB) += slab.o
> diff --git a/mm/test_pmalloc.c b/mm/test_pmalloc.c
> new file mode 100644
> index 000000000000..df7ecc91c6a4
> --- /dev/null
> +++ b/mm/test_pmalloc.c
> @@ -0,0 +1,100 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * test_pmalloc.c
> + *
> + * (C) Copyright 2018 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <[email protected]>
> + */
> +
> +#include <linux/pmalloc.h>
> +#include <linux/mm.h>
> +#include <linux/test_pmalloc.h>
> +#include <linux/bug.h>
> +
> +#define SIZE_1 (PAGE_SIZE * 3)
> +#define SIZE_2 1000
> +
> +static inline bool validate_alloc(bool expected, void *addr,
> + unsigned long size)
> +{
> + bool test;
> +
> + test = is_pmalloc_object(addr, size) > 0;
> + pr_notice("must be %s: %s",
> + expected ? "ok" : "no", test ? "ok" : "no");
> + return test == expected;
> +}
> +
> +#define is_alloc_ok(variable, size) \
> + validate_alloc(true, variable, size)
> +
> +#define is_alloc_no(variable, size) \
> + validate_alloc(false, variable, size)
> +
> +void test_pmalloc(void)
> +{
> + struct gen_pool *pool_unprot;
> + struct gen_pool *pool_prot;
> + void *var_prot, *var_unprot, *var_vmall;
> +
> + pr_notice("pmalloc-selftest");
> + pool_unprot = pmalloc_create_pool("unprotected", 0);
> + if (unlikely(!pool_unprot))
> + goto error;
> + pool_prot = pmalloc_create_pool("protected", 0);
> + if (unlikely(!(pool_prot)))
> + goto error_release;
> +
> + pr_notice("Testing allocation capability");
> + var_unprot = pmalloc(pool_unprot, SIZE_1 - 1, GFP_KERNEL);
> + var_prot = pmalloc(pool_prot, SIZE_1, GFP_KERNEL);
> + *(int *)var_prot = 0;
> + var_vmall = vmalloc(SIZE_2);
> +
> +
> + pr_notice("Test correctness of is_pmalloc_object()");
> + WARN_ON(unlikely(!is_alloc_ok(var_unprot, 10)));
> + WARN_ON(unlikely(!is_alloc_ok(var_unprot, SIZE_1)));
> + WARN_ON(unlikely(!is_alloc_ok(var_unprot, PAGE_SIZE)));
> + WARN_ON(unlikely(!is_alloc_no(var_unprot, SIZE_1 + 1)));
> + WARN_ON(unlikely(!is_alloc_no(var_vmall, 10)));
> +
> +
> + pfree(pool_unprot, var_unprot);
> + vfree(var_vmall);
> +
> + pmalloc_protect_pool(pool_prot);
> +
> + /*
> + * This will intentionally trigger a WARN, because the pool being
> + * allocated from is already protected.
> + */
> + pr_notice("Test allocation from a protected pool."
> + "Expect WARN in pmalloc");
> + if (unlikely(pmalloc(pool_prot, 10, GFP_KERNEL)))
> + WARN(true, "no memory from a protected pool");
> +
> + /*
> + * This will intentionally trigger a WARN because the pool being
> + * destroyed is not protected, which is unusual and should happen
> + * on error paths only, where probably other warnings are already
> + * displayed.
> + */
> + pr_notice("pmalloc-selftest:"
> + " Expect WARN in pmalloc_pool_set_protection below.");
> + pmalloc_destroy_pool(pool_unprot);
> + pr_notice("pmalloc-selftest:"
> + "Critical point for expected WARN passed.");
> +
> + /* This must not cause WARNings */
> + pr_notice("pmalloc-selftest:"
> + "Expect no WARN below.");
> + pmalloc_destroy_pool(pool_prot);
> + pr_notice("pmalloc-selftest:"
> + "Critical point for unexpected WARN passed.");
> + return;
> +error_release:
> + pmalloc_destroy_pool(pool_unprot);
> +error:
> + WARN(true, "Unable to allocate memory for pmalloc selftest.");
> +}
On 2/28/18 12:06 PM, Igor Stoppa wrote:
> Verify that pmalloc read-only protection is in place: trying to
> overwrite a protected variable will crash the kernel.
>
> Signed-off-by: Igor Stoppa <[email protected]>
> ---
> drivers/misc/lkdtm.h | 1 +
> drivers/misc/lkdtm_core.c | 3 +++
> drivers/misc/lkdtm_perms.c | 28 ++++++++++++++++++++++++++++
> 3 files changed, 32 insertions(+)
>
> diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
> index 9e513dcfd809..dcda3ae76ceb 100644
> --- a/drivers/misc/lkdtm.h
> +++ b/drivers/misc/lkdtm.h
> @@ -38,6 +38,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void);
> void __init lkdtm_perms_init(void);
> void lkdtm_WRITE_RO(void);
> void lkdtm_WRITE_RO_AFTER_INIT(void);
> +void lkdtm_WRITE_RO_PMALLOC(void);
Does this need some sort of #ifdef too?
> void lkdtm_WRITE_KERN(void);
> void lkdtm_EXEC_DATA(void);
> void lkdtm_EXEC_STACK(void);
> diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
> index 2154d1bfd18b..c9fd42bda6ee 100644
> --- a/drivers/misc/lkdtm_core.c
> +++ b/drivers/misc/lkdtm_core.c
> @@ -155,6 +155,9 @@ static const struct crashtype crashtypes[] = {
> CRASHTYPE(ACCESS_USERSPACE),
> CRASHTYPE(WRITE_RO),
> CRASHTYPE(WRITE_RO_AFTER_INIT),
> +#ifdef CONFIG_PROTECTABLE_MEMORY
> + CRASHTYPE(WRITE_RO_PMALLOC),
> +#endif
> CRASHTYPE(WRITE_KERN),
> CRASHTYPE(REFCOUNT_INC_OVERFLOW),
> CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
> diff --git a/drivers/misc/lkdtm_perms.c b/drivers/misc/lkdtm_perms.c
> index 53b85c9d16b8..0ac9023fd2b0 100644
> --- a/drivers/misc/lkdtm_perms.c
> +++ b/drivers/misc/lkdtm_perms.c
> @@ -9,6 +9,7 @@
> #include <linux/vmalloc.h>
> #include <linux/mman.h>
> #include <linux/uaccess.h>
> +#include <linux/pmalloc.h>
> #include <asm/cacheflush.h>
>
> /* Whether or not to fill the target memory area with do_nothing(). */
> @@ -104,6 +105,33 @@ void lkdtm_WRITE_RO_AFTER_INIT(void)
> *ptr ^= 0xabcd1234;
> }
>
> +#ifdef CONFIG_PROTECTABLE_MEMORY
> +void lkdtm_WRITE_RO_PMALLOC(void)
> +{
> + struct gen_pool *pool;
> + int *i;
> +
> + pool = pmalloc_create_pool("pool", 0);
> + if (unlikely(!pool)) {
> + pr_info("Failed preparing pool for pmalloc test.");
> + return;
> + }
> +
> + i = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL);
> + if (unlikely(!i)) {
> + pr_info("Failed allocating memory for pmalloc test.");
> + pmalloc_destroy_pool(pool);
> + return;
> + }
> +
> + *i = INT_MAX;
> + pmalloc_protect_pool(pool);
> +
> + pr_info("attempting bad pmalloc write at %p\n", i);
> + *i = 0;
OK, now I'm on the right version of this patch series, same comment
applies. I don't get the local *i assignment at the end of the
function, but seems harmless.
Except the two minor comments, otherwise,
Reviewed-by: Jay Freyensee <[email protected]>
> +}
> +#endif
> +
> void lkdtm_WRITE_KERN(void)
> {
> size_t size;
Minus the comment-fixes Mike Rapoport mentioned, looks good:
Reviewed-by: Jay Freyensee <[email protected]>
On 2/28/18 12:06 PM, Igor Stoppa wrote:
> Detailed documentation about the protectable memory allocator.
>
> Signed-off-by: Igor Stoppa <[email protected]>
> ---
> Documentation/core-api/index.rst | 1 +
> Documentation/core-api/pmalloc.rst | 111 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 112 insertions(+)
> create mode 100644 Documentation/core-api/pmalloc.rst
>
> diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst
> index c670a8031786..8f5de42d6571 100644
> --- a/Documentation/core-api/index.rst
> +++ b/Documentation/core-api/index.rst
> @@ -25,6 +25,7 @@ Core utilities
> genalloc
> errseq
> printk-formats
> + pmalloc
>
> Interfaces for kernel debugging
> ===============================
> diff --git a/Documentation/core-api/pmalloc.rst b/Documentation/core-api/pmalloc.rst
> new file mode 100644
> index 000000000000..8fb9c9d3171b
> --- /dev/null
> +++ b/Documentation/core-api/pmalloc.rst
> @@ -0,0 +1,111 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Protectable memory allocator
> +============================
> +
> +Purpose
> +-------
> +
> +The pmalloc library is meant to provide R/O status to data that, for some
> +reason, could neither be declared as constant, nor could it take advantage
> +of the qualifier __ro_after_init, but is write-once and read-only in spirit.
> +It protects data from both accidental and malicious overwrites.
> +
> +Example: A policy that is loaded from userspace.
> +
> +
> +Concept
> +-------
> +
> +pmalloc builds on top of genalloc, using the same concept of memory pools.
> +
> +The value added by pmalloc is that now the memory contained in a pool can
> +become R/O, for the rest of the life of the pool.
> +
> +Different kernel drivers and threads can use different pools, for finer
> +control of what becomes R/O and when. And for improved lockless concurrency.
> +
> +
> +Caveats
> +-------
> +
> +- Memory freed while a pool is not yet protected will be reused.
> +
> +- Once a pool is protected, it's not possible to allocate any more memory
> + from it.
> +
> +- Memory "freed" from a protected pool indicates that such memory is not
> + in use anymore by the requester; however, it will not become available
> + for further use, until the pool is destroyed.
> +
> +- pmalloc does not provide locking support with respect to allocating vs
> + protecting an individual pool, for performance reasons.
> + It is recommended not to share the same pool between unrelated functions.
> + Should sharing be a necessity, the user of the shared pool is expected
> + to implement locking for that pool.
> +
> +- pmalloc uses genalloc to optimize the use of the space it allocates
> + through vmalloc. Some more TLB entries will be used, however less than
> + in the case of using vmalloc directly. The exact number depends on the
> + size of each allocation request and possible slack.
> +
> +- Considering that not much data is supposed to be dynamically allocated
> + and then marked as read-only, it shouldn't be an issue that the address
> + range for pmalloc is limited, on 32-bit systems.
> +
> +- Regarding SMP systems, the allocations are expected to happen mostly
> + during an initial transient, after which there should be no more need to
> + perform cross-processor synchronizations of page tables.
> +
> +- To facilitate the conversion of existing code to pmalloc pools, several
> + helper functions are provided, mirroring their kmalloc counterparts.
> +
> +
> +Use
> +---
> +
> +The typical sequence, when using pmalloc, is:
> +
> +1. create a pool
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc_create_pool
> +
> +2. [optional] pre-allocate some memory in the pool
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc_prealloc
> +
> +3. issue one or more allocation requests to the pool with locking as needed
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pzalloc
> +
> +4. initialize the memory obtained with desired values
> +
> +5. [optional] iterate over points 3 & 4 as needed
> +
> +6. write-protect the pool
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc_protect_pool
> +
> +7. use in read-only mode the handles obtained through the allocations
> +
> +8. [optional] release all the memory allocated
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pfree
> +
> +9. [optional, but depends on point 8] destroy the pool
> +
> +.. kernel-doc:: include/linux/pmalloc.h
> + :functions: pmalloc_destroy_pool
> +
> +API
> +---
> +
> +.. kernel-doc:: include/linux/pmalloc.h
On 05/03/2018 21:00, J Freyensee wrote:
> .
> .
>
>
> On 2/28/18 12:06 PM, Igor Stoppa wrote:
>> +
>> +/**
>> + * gen_pool_dma_alloc() - allocate special memory from the pool for DMA usage
>> + * @pool: pool to allocate from
>> + * @size: number of bytes to allocate from the pool
>> + * @dma: dma-view physical address return value. Use NULL if unneeded.
>> + *
>> + * Allocate the requested number of bytes from the specified pool.
>> + * Uses the pool allocation function (with first-fit algorithm by default).
>> + * Can not be used in NMI handler on architectures without
>> + * NMI-safe cmpxchg implementation.
>> + *
>> + * Return:
>> + * * address of the memory allocated - success
>> + * * NULL - error
>> + */
>> +void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma);
>> +
>
> OK, so gen_pool_dma_alloc() is defined here, which believe is the API
> line being drawn for this series.
>
> so,
> .
> .
> .
>>
>>
>> /**
>> - * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
>> + * gen_pool_dma_alloc() - allocate special memory from the pool for DMA usage
>> * @pool: pool to allocate from
>> * @size: number of bytes to allocate from the pool
>> * @dma: dma-view physical address return value. Use NULL if unneeded.
>> @@ -342,14 +566,15 @@ EXPORT_SYMBOL(gen_pool_alloc_algo);
>> * Uses the pool allocation function (with first-fit algorithm by default).
>> * Can not be used in NMI handler on architectures without
>> * NMI-safe cmpxchg implementation.
>> + *
>> + * Return:
>> + * * address of the memory allocated - success
>> + * * NULL - error
>> */
>> void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
>> {
>> unsigned long vaddr;
>>
>> - if (!pool)
>> - return NULL;
>> -
> why is this being removed? I don't believe this code was getting
> removed from your v17 series patches.
Because, as Matthew Wilcox pointed out [1] (well, that's how I
understood it) de-referencing a NULL pointer will cause the kernel to
complain loudly.
Where is the NULL pointer coming from?
a) from a bug in the user of the API - in that case it will be noticed,
reported and fixed, that is how also other in-kernel APIs work
b) from an attacker - it will still trigger an error from the kernel,
but it cannot really do much else, besides crashing repeatedly and
causing a DOS. However, there are so many other places that could be
under similar attack, that it doesn't seem to make a difference having a
check here only.
If the value was coming from userspace, that would be a completely
different case and some sort of sanitation would be mandatory.
> Otherwise, looks good,
>
> Reviewed-by: Jay Freyensee <[email protected]>
thanks
[1] http://www.openwall.com/lists/kernel-hardening/2018/02/26/16
--
igor
On 06/03/18 18:05, Igor Stoppa wrote:
> On 06/03/2018 16:10, Matthew Wilcox wrote:
[...]
>> This seems unnecessarily complicated.
>
> TBH it seemed to me a natural extension of the existing encoding :-)
BTW, to provide some background, this is where it begun:
http://www.openwall.com/lists/kernel-hardening/2017/08/18/4
Probably that comment about "keeping existing behavior and managing two
bitmaps locklessly" is what made me think of growing the 1-bit-per-unit
into a 1-word-per-unit.
--
igor
On 06/03/18 19:20, J Freyensee wrote:
> On 2/28/18 12:06 PM, Igor Stoppa wrote:
[...]
>> void __init lkdtm_perms_init(void);
>> void lkdtm_WRITE_RO(void);
>> void lkdtm_WRITE_RO_AFTER_INIT(void);
>> +void lkdtm_WRITE_RO_PMALLOC(void);
>
> Does this need some sort of #ifdef too?
Not strictly. It's just a function declaration.
As long as it is not used, the linker will not complain.
The #ifdef placed around the use and definition is sufficient, from a
correctness perspective.
But it's a different question if there is any standard in linux about
hiding also the declaration.
I am not very fond of #ifdefs, so when I can I try to avoid them.
>> + pr_info("attempting bad pmalloc write at %p\n", i);
>> + *i = 0;
>
> OK, now I'm on the right version of this patch series, same comment
> applies. I don't get the local *i assignment at the end of the
> function, but seems harmless.
Because that's the whole point of the function: prove that pmalloc
protection works (see the message in the pr_info one line above).
The function is supposed to do:
* create a pool
* allocate memory from it
* protect it
* try to alter it (and crash)
*i = 0; performs the last step
--
igor
On 06/03/18 05:59, J Freyensee wrote:
[...]
>> +config PROTECTABLE_MEMORY
>> + bool
>> + depends on MMU
>
>
> Curious, would you also want to depend on "SECURITY" as well, as this is
> being advertised as a compliment to __read_only_after_init, per the file
> header comments, as I'm assuming ro_after_init would be disabled if the
> SECURITY Kconfig selection is *NOT* selected?
__ro_after_init is configured like this:
#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
bool rodata_enabled __ro_after_init = true;
But even if __ro_after_init and pmalloc are conceptually similar, in
practice they have - potentially - different constraints.
1) the __ro_after_init segment belongs to linear kernel memory
2) the pmalloc pools belong to vmalloc memory
There is one extra layer of indirection in pmalloc.
I am not an expert of MMUs but I suppose there might be types where it
is possible to mark pages as RO but it's not possible to have virtual
memory.
If (and this is a big "if") such MMUs exist and are supported by linux,
then __ro_after_init would be possible, while pmalloc would not be.
So it seemed more correct to focus specifically on hte enablers required
by pmalloc to perform correctly.
Open Question:
Is it ok that the API disappears in case the enablers are missing?
Or should it fall back to something else?
Dealing with lack of ReadOnly support would be pretty simple, it would
be enough to make the write-Protection conditional.
But what to do if virtual mapping is not supported?
kmalloc might not have the ability to support large requests made toward
pmalloc and this would possibly cause runtime failures.
--
igor
On 06/03/18 15:19, Mike Rapoport wrote:
> On Wed, Feb 28, 2018 at 10:06:14PM +0200, Igor Stoppa wrote:
[...]
> If I'm not mistaken, several kernel-doc descriptions are duplicated now.
> Can you please keep a single copy? ;-)
What's the preferred approach?
Document the functions that are API in the .h file and leave in the .c
those which are not API?
[...]
>> + * The alignment at which to perform the research for sequence of empty
>
> ^ search?
yes
>> + * get_boundary() - verifies address, then measure length.
>
> There's some lack of consistency between the name and implementation and
> the description.
> It seems that it would be simpler to actually make it get_length() and
> return the length of the allocation or nentries if the latter is smaller.
> Then in gen_pool_free() there will be no need to recalculate nentries
> again.
There is an error in the documentation. I'll explain below.
>
>> * @map: pointer to a bitmap
>> - * @start: a bit position in @map
>> - * @nr: number of bits to set
>> + * @start_entry: the index of the first entry in the bitmap
>> + * @nentries: number of entries to alter
>
> Maybe: "maximal number of entries to check"?
No, it's actually the total number of entries in the chunk.
[...]
>> + return nentries - start_entry;
>
> Shouldn't it be "nentries + start_entry"?
And in the light of the correct comment, also what I am doing should be
now more clear:
* start_entry is the index of the initial entry
* nentries is the number of entries in the chunk
If I iterate over the rest of the chunk:
(i = start_entry + 1; i < nentries; i++)
without finding either another HEAD or an empty slot, then it means I
was measuring the length of the last allocation in the chunk, which was
taking up all the space, to the end.
Simple example:
- chunk with 7 entries -> nentries is 7
- start_entry is 2, meaning that the last allocation starts from the 3rd
element, iow it occupies indexes from 2 to 6, for a total of 5 entries
- so the length is (nentries - start_entry) = (7 - 2) = 5
But yeah, the kerneldoc was wrong.
[...]
>> - * gen_pool_alloc_algo - allocate special memory from the pool
>> + * gen_pool_alloc_algo() - allocate special memory from the pool
>
> + using specified algorithm
ok
>
>> * @pool: pool to allocate from
>> * @size: number of bytes to allocate from the pool
>> * @algo: algorithm passed from caller
>> @@ -285,14 +502,18 @@ EXPORT_SYMBOL(gen_pool_alloc);
>> * Uses the pool allocation function (with first-fit algorithm by default).
>
> "uses the provided @algo function to find room for the allocation"
ok
--
igor
On 07/03/18 16:48, Igor Stoppa wrote:
>
>
> On 06/03/18 15:19, Mike Rapoport wrote:
>> On Wed, Feb 28, 2018 at 10:06:14PM +0200, Igor Stoppa wrote:
[...]
>>> + * get_boundary() - verifies address, then measure length.
>>
>> There's some lack of consistency between the name and implementation and
>> the description.
>> It seems that it would be simpler to actually make it get_length() and
>> return the length of the allocation or nentries if the latter is smaller.
>> Then in gen_pool_free() there will be no need to recalculate nentries
>> again.
>
> There is an error in the documentation. I'll explain below.
Argh, I do not know why I came out with that.
Yes, your comment is correct. I've modified the function accordingly and
it is simpler.
I will post it in the next revision.
--
igor
On 3/7/18 5:18 AM, Igor Stoppa wrote:
>
> On 06/03/18 19:20, J Freyensee wrote:
>
>> On 2/28/18 12:06 PM, Igor Stoppa wrote:
> [...]
>
>>> void __init lkdtm_perms_init(void);
>>> void lkdtm_WRITE_RO(void);
>>> void lkdtm_WRITE_RO_AFTER_INIT(void);
>>> +void lkdtm_WRITE_RO_PMALLOC(void);
>> Does this need some sort of #ifdef too?
> Not strictly. It's just a function declaration.
> As long as it is not used, the linker will not complain.
> The #ifdef placed around the use and definition is sufficient, from a
> correctness perspective.
>
> But it's a different question if there is any standard in linux about
> hiding also the declaration.
I'd prefer hiding it if it's contents are being ifdef'ed out, but I
really think it's more of a maintainer preference question.
>
> I am not very fond of #ifdefs, so when I can I try to avoid them.
>
>
On March 7, 2018 4:48:25 PM GMT+02:00, Igor Stoppa <[email protected]> wrote:
>
>
>On 06/03/18 15:19, Mike Rapoport wrote:
>> On Wed, Feb 28, 2018 at 10:06:14PM +0200, Igor Stoppa wrote:
>
>[...]
>
>> If I'm not mistaken, several kernel-doc descriptions are duplicated
>now.
>> Can you please keep a single copy? ;-)
>
>What's the preferred approach?
>Document the functions that are API in the .h file and leave in the .c
>those which are not API?
I aggree with Matthew: "we usually recommend putting it with the definition so it's more likely to be updated."
I couldn't find the doc with this recommendation, though :)
>[...]
>
>>> + * The alignment at which to perform the research for sequence of
>empty
>>
>> ^ search?
>
>yes
>
>>> + * get_boundary() - verifies address, then measure length.
>>
>> There's some lack of consistency between the name and implementation
>and
>> the description.
>> It seems that it would be simpler to actually make it get_length()
>and
>> return the length of the allocation or nentries if the latter is
>smaller.
>> Then in gen_pool_free() there will be no need to recalculate nentries
>> again.
>
>There is an error in the documentation. I'll explain below.
>
>>
>>> * @map: pointer to a bitmap
>>> - * @start: a bit position in @map
>>> - * @nr: number of bits to set
>>> + * @start_entry: the index of the first entry in the bitmap
>>> + * @nentries: number of entries to alter
>>
>> Maybe: "maximal number of entries to check"?
>
>No, it's actually the total number of entries in the chunk.
>
>[...]
>
>>> + return nentries - start_entry;
>>
>> Shouldn't it be "nentries + start_entry"?
>
>And in the light of the correct comment, also what I am doing should be
>now more clear:
>
>* start_entry is the index of the initial entry
>* nentries is the number of entries in the chunk
>
>If I iterate over the rest of the chunk:
>
>(i = start_entry + 1; i < nentries; i++)
>
>without finding either another HEAD or an empty slot, then it means I
>was measuring the length of the last allocation in the chunk, which was
>taking up all the space, to the end.
>
>Simple example:
>
>- chunk with 7 entries -> nentries is 7
>- start_entry is 2, meaning that the last allocation starts from the
>3rd
>element, iow it occupies indexes from 2 to 6, for a total of 5 entries
>- so the length is (nentries - start_entry) = (7 - 2) = 5
>
>
>But yeah, the kerneldoc was wrong.
>
>[...]
>
>>> - * gen_pool_alloc_algo - allocate special memory from the pool
>>> + * gen_pool_alloc_algo() - allocate special memory from the pool
>>
>> + using specified algorithm
>
>ok
>
>>
>>> * @pool: pool to allocate from
>>> * @size: number of bytes to allocate from the pool
>>> * @algo: algorithm passed from caller
>>> @@ -285,14 +502,18 @@ EXPORT_SYMBOL(gen_pool_alloc);
>>> * Uses the pool allocation function (with first-fit algorithm by
>default).
>>
>> "uses the provided @algo function to find room for the allocation"
>
>ok
>
>--
>igor
--
Sincerely yours,
Mike.
On Wed, Feb 28, 2018 at 10:06:17PM +0200, Igor Stoppa wrote:
> struct gen_pool *pmalloc_create_pool(const char *name,
> int min_alloc_order);
> int is_pmalloc_object(const void *ptr, const unsigned long n);
> bool pmalloc_prealloc(struct gen_pool *pool, size_t size);
> void *pmalloc(struct gen_pool *pool, size_t size, gfp_t gfp);
> static inline void *pzalloc(struct gen_pool *pool, size_t size, gfp_t gfp)
> static inline void *pmalloc_array(struct gen_pool *pool, size_t n,
> size_t size, gfp_t flags)
> static inline void *pcalloc(struct gen_pool *pool, size_t n,
> size_t size, gfp_t flags)
> static inline char *pstrdup(struct gen_pool *pool, const char *s, gfp_t gfp)
> int pmalloc_protect_pool(struct gen_pool *pool);
> static inline void pfree(struct gen_pool *pool, const void *addr)
> int pmalloc_destroy_pool(struct gen_pool *pool);
Do you have users for all these functions? I'm particularly sceptical of
pfree(). To my mind, a user wants to:
pmalloc_create();
pmalloc(); * N
pmalloc_protect();
...
pmalloc_destroy();
I don't mind the pstrdup, pcalloc, pmalloc_array, pzalloc variations, but
I don't know why you need is_pmalloc_object().
On 12/03/18 21:13, Matthew Wilcox wrote:
> On Wed, Feb 28, 2018 at 10:06:17PM +0200, Igor Stoppa wrote:
>> struct gen_pool *pmalloc_create_pool(const char *name,
>> int min_alloc_order);
>> int is_pmalloc_object(const void *ptr, const unsigned long n);
>> bool pmalloc_prealloc(struct gen_pool *pool, size_t size);
>> void *pmalloc(struct gen_pool *pool, size_t size, gfp_t gfp);
>> static inline void *pzalloc(struct gen_pool *pool, size_t size, gfp_t gfp)
>> static inline void *pmalloc_array(struct gen_pool *pool, size_t n,
>> size_t size, gfp_t flags)
>> static inline void *pcalloc(struct gen_pool *pool, size_t n,
>> size_t size, gfp_t flags)
>> static inline char *pstrdup(struct gen_pool *pool, const char *s, gfp_t gfp)
>> int pmalloc_protect_pool(struct gen_pool *pool);
>> static inline void pfree(struct gen_pool *pool, const void *addr)
>> int pmalloc_destroy_pool(struct gen_pool *pool);
>
> Do you have users for all these functions? I'm particularly sceptical of
> pfree().
The typical case is when rolling back allocations, on an error path.
For example, with SELinux, the userspace provides the policy, which gets
processed and converted into a policyDB, where every policy maps to
several structures allocated dynamically.
The allocation is not transactional. In case a policy turns out to be
bad/broken, while being interpreted, those structures that were
initially allocated for that policy, must be freed.
Since pmalloc is meant to be a drop in replacement for k/vmalloc, it
needs to provide also pfree.
> To my mind, a user wants to:
>
> pmalloc_create();
> pmalloc(); * N
> pmalloc_protect();
> ...
> pmalloc_destroy();
This is the simplest case, but also the error path must be supported.
> I don't mind the pstrdup, pcalloc, pmalloc_array, pzalloc variations, but
All those functions turned out to be necessary when converting SELinux
to pmalloc.
Yes, I haven't published this code yet, but I was hoping to first be
done with pmalloc and then move on to SELinux, which I suspect will be
harder to chew :-/
> I don't know why you need is_pmalloc_object().
Because of hardened usercopy [1]:
On 23/05/17 00:38, Kees Cook wrote:
[...]
> I'd like hardened usercopy to grow knowledge of these
> allocations so we can bounds-check objects. Right now, mm/usercopy.c
> just looks at PageSlab(page) to decide if it should do slab checks. I
> think adding a check for this type of object would be very important
> there.
[1] http://www.openwall.com/lists/kernel-hardening/2017/05/23/17
--
igor