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 v15:
[http://www.openwall.com/lists/kernel-hardening/2018/02/11/4]
- Fixed remaining broken comments
- Fixed remaining broken "Returns" instead of "Return:" in kernel-doc
- Converted "Return:" values to lists
- Fixed SPDX license statements
Igor Stoppa (6):
genalloc: track beginning of allocations
genalloc: selftest
struct page: add field for vm_struct
Protectable Memory
Pmalloc: self-test
Documentation for Pmalloc
Documentation/core-api/index.rst | 1 +
Documentation/core-api/pmalloc.rst | 114 +++++++
include/linux/genalloc-selftest.h | 26 ++
include/linux/genalloc.h | 7 +-
include/linux/mm_types.h | 1 +
include/linux/pmalloc.h | 242 ++++++++++++++
include/linux/vmalloc.h | 1 +
init/main.c | 2 +
lib/Kconfig | 15 +
lib/Makefile | 1 +
lib/genalloc-selftest.c | 400 ++++++++++++++++++++++
lib/genalloc.c | 658 +++++++++++++++++++++++++++----------
mm/Kconfig | 15 +
mm/Makefile | 2 +
mm/pmalloc-selftest.c | 64 ++++
mm/pmalloc-selftest.h | 24 ++
mm/pmalloc.c | 501 ++++++++++++++++++++++++++++
mm/usercopy.c | 33 ++
mm/vmalloc.c | 18 +-
19 files changed, 1950 insertions(+), 175 deletions(-)
create mode 100644 Documentation/core-api/pmalloc.rst
create mode 100644 include/linux/genalloc-selftest.h
create mode 100644 include/linux/pmalloc.h
create mode 100644 lib/genalloc-selftest.c
create mode 100644 mm/pmalloc-selftest.c
create mode 100644 mm/pmalloc-selftest.h
create mode 100644 mm/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
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/genalloc.h | 4 +-
lib/genalloc.c | 631 ++++++++++++++++++++++++++++++++++-------------
2 files changed, 465 insertions(+), 170 deletions(-)
diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index 872f930f1b06..dcaa33e74b1c 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 */
};
/*
diff --git a/lib/genalloc.c b/lib/genalloc.c
index ca06adc4f445..87f62f31b52f 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>
@@ -36,118 +104,247 @@
#include <linux/genalloc.h>
#include <linux/of_device.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, int start_entry, 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
+ *
+ * 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.
*
- * 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.
+ * Return:
+ * * 0 - success
+ * * remaining entries - failure
*/
-static int bitmap_clear_ll(unsigned long *map, int start, int nr)
+static int alter_bitmap_ll(bool alteration, unsigned long *map,
+ int start_entry, 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;
+ int nbits;
+ int bits_to_write;
+ 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 +364,7 @@ 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 +374,20 @@ 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);
+ int nentries;
+ 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 +406,13 @@ 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 +433,7 @@ 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
@@ -248,7 +451,7 @@ void gen_pool_destroy(struct gen_pool *pool)
list_del(&chunk->next_chunk);
end_bit = chunk_size(chunk) >> order;
- bit = find_next_bit(chunk->bits, end_bit, 0);
+ bit = find_next_bit(chunk->entries, end_bit, 0);
BUG_ON(bit < end_bit);
kfree(chunk);
@@ -259,7 +462,7 @@ void gen_pool_destroy(struct gen_pool *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 +470,10 @@ 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 +482,7 @@ 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
@@ -285,6 +492,10 @@ 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)
@@ -292,7 +503,7 @@ unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
struct gen_pool_chunk *chunk;
unsigned long addr = 0;
int order = pool->min_alloc_order;
- int nbits, start_bit, end_bit, remain;
+ int nentries, start_entry, end_entry, remain;
#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
BUG_ON(in_nmi());
@@ -301,29 +512,32 @@ 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 +547,7 @@ 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.
@@ -342,6 +556,10 @@ 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)
{
@@ -362,10 +580,10 @@ 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
@@ -375,22 +593,29 @@ 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;
+ 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);
+ start_entry = (addr - chunk->start_addr) >> order;
+ remaining_entries = (chunk->end_addr - addr) >> order;
+ boundary = get_boundary(chunk->entries, start_entry,
+ remaining_entries);
+ BUG_ON(boundary < 0);
+ nentries = boundary - start_entry;
+ BUG_ON(size &&
+ (nentries != mem_to_units(size, order)));
+ remain = alter_bitmap_ll(CLEAR_BITS, chunk->entries,
+ start_entry, nentries);
BUG_ON(remain);
- size = nbits << order;
- atomic_long_add(size, &chunk->avail);
+ atomic_long_add(nentries << order, &chunk->avail);
rcu_read_unlock();
return;
}
@@ -401,7 +626,7 @@ void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
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
@@ -423,13 +648,16 @@ 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)
@@ -452,10 +680,10 @@ 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 +699,10 @@ 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 +718,7 @@ 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
@@ -514,32 +742,48 @@ 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)
{
- 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,
@@ -547,23 +791,34 @@ unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
{
struct genpool_data_align *alignment;
unsigned long align_mask;
+ unsigned long bit_index;
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,
@@ -571,82 +826,113 @@ unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
{
struct genpool_data_fixed *fixed_data;
int order;
- unsigned long offset_bit;
- unsigned long start_bit;
+ 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 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_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;
+ int 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);
static void devm_gen_pool_release(struct device *dev, void *res)
{
@@ -668,11 +954,14 @@ 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 +976,7 @@ 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 +985,10 @@ 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)
@@ -738,14 +1031,16 @@ 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)
--
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.
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/genalloc.h | 3 +
include/linux/pmalloc.h | 242 +++++++++++++++++++++++
include/linux/vmalloc.h | 1 +
lib/genalloc.c | 27 +++
mm/Kconfig | 6 +
mm/Makefile | 1 +
mm/pmalloc.c | 499 +++++++++++++++++++++++++++++++++++++++++++++++
mm/usercopy.c | 33 ++++
8 files changed, 812 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 dcaa33e74b1c..b6c4cea9fbd8 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -121,6 +121,9 @@ extern unsigned long gen_pool_alloc_algo(struct gen_pool *, size_t,
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_flush_chunk(struct gen_pool *pool,
+ struct gen_pool_chunk *chunk);
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 *);
diff --git a/include/linux/pmalloc.h b/include/linux/pmalloc.h
new file mode 100644
index 000000000000..afc2068d5545
--- /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
+ *
+ * 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 87f62f31b52f..24ed35035095 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -625,6 +625,33 @@ 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;
+
+ if (unlikely(!(pool && chunk)))
+ return;
+
+ 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..be578fbdce6d 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -760,3 +760,9 @@ config GUP_BENCHMARK
performance of get_user_pages_fast().
See tools/testing/selftests/vm/gup_benchmark.c
+
+config PROTECTABLE_MEMORY
+ bool
+ 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..abddba90a9f6
--- /dev/null
+++ b/mm/pmalloc.c
@@ -0,0 +1,499 @@
+// 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 <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 (!name) {
+ WARN_ON(1);
+ 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 int check_alloc_params(struct gen_pool *pool, size_t req_size)
+{
+ struct pmalloc_data *data;
+
+ if (unlikely(!req_size || !pool))
+ return -1;
+
+ data = pool->data;
+
+ if (data == NULL)
+ return -1;
+
+ if (unlikely(data->protected)) {
+ WARN_ON(1);
+ return -1;
+ }
+ return 0;
+}
+
+
+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;
+
+ if (check_alloc_params(pool, size))
+ return false;
+
+ /* 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 (check_alloc_params(pool, size))
+ 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;
+
+ BUG_ON(chunk_size & (PAGE_SIZE - 1));
+
+ 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;
+
+ if (unlikely(!pool))
+ return -EINVAL;
+
+ data = pool->data;
+
+ if (unlikely(!data))
+ return -EINVAL;
+
+ if (unlikely(data->protected == protection)) {
+ WARN_ON(1);
+ 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;
+
+ if (unlikely(pool == NULL))
+ return -EINVAL;
+
+ data = pool->data;
+
+ if (unlikely(data == NULL))
+ return -EINVAL;
+
+ 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
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.
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/genalloc-selftest.h | 26 +++
init/main.c | 2 +
lib/Kconfig | 15 ++
lib/Makefile | 1 +
lib/genalloc-selftest.c | 400 ++++++++++++++++++++++++++++++++++++++
5 files changed, 444 insertions(+)
create mode 100644 include/linux/genalloc-selftest.h
create mode 100644 lib/genalloc-selftest.c
diff --git a/include/linux/genalloc-selftest.h b/include/linux/genalloc-selftest.h
new file mode 100644
index 000000000000..e0ac8f963abc
--- /dev/null
+++ b/include/linux/genalloc-selftest.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * genalloc-selftest.h
+ *
+ * (C) Copyright 2017 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+
+#ifndef __LINUX_GENALLOC_SELFTEST_H
+#define __LINUX_GENALLOC_SELFTEST_H
+
+
+#ifdef CONFIG_GENERIC_ALLOCATOR_SELFTEST
+
+#include <linux/genalloc.h>
+
+void genalloc_selftest(void);
+
+#else
+
+static inline void genalloc_selftest(void){};
+
+#endif
+
+#endif
diff --git a/init/main.c b/init/main.c
index a8100b954839..fb844aa3eb8c 100644
--- a/init/main.c
+++ b/init/main.c
@@ -89,6 +89,7 @@
#include <linux/io.h>
#include <linux/cache.h>
#include <linux/rodata_test.h>
+#include <linux/genalloc-selftest.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -660,6 +661,7 @@ asmlinkage __visible void __init start_kernel(void)
*/
mem_encrypt_init();
+ genalloc_selftest();
#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..0d526c004e81 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -287,6 +287,21 @@ config DECOMPRESS_LZ4
config GENERIC_ALLOCATOR
bool
+config GENERIC_ALLOCATOR_SELFTEST
+ 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 GENERIC_ALLOCATOR_SELFTEST_VERBOSE
+ bool "make the genalloc tester more verbose"
+ default n
+ select GENERIC_ALLOCATOR_SELFTEST
+ 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..fadb30abde08 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-$(CONFIG_GENERIC_ALLOCATOR_SELFTEST) += genalloc-selftest.o
obj-$(CONFIG_842_COMPRESS) += 842/
obj-$(CONFIG_842_DECOMPRESS) += 842/
diff --git a/lib/genalloc-selftest.c b/lib/genalloc-selftest.c
new file mode 100644
index 000000000000..e86be22c5512
--- /dev/null
+++ b/lib/genalloc-selftest.c
@@ -0,0 +1,400 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * genalloc-selftest.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/genalloc-selftest.h>
+/*
+ * 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_GENERIC_ALLOCATOR_SELFTEST_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 genalloc_selftest(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 obtian
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.
As example, the function find_vm_area is reimplemented, to take advantage
of the newly introduced field.
Signed-off-by: Igor Stoppa <[email protected]>
---
include/linux/mm_types.h | 1 +
mm/vmalloc.c | 18 +++++++++++++-----
2 files changed, 14 insertions(+), 5 deletions(-)
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 673942094328..9404ffd0ee98 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1466,13 +1466,16 @@ struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
*/
struct vm_struct *find_vm_area(const void *addr)
{
- struct vmap_area *va;
+ struct page *page;
- va = find_vmap_area((unsigned long)addr);
- if (va && va->flags & VM_VM_AREA)
- return va->vm;
+ if (unlikely(!is_vmalloc_addr(addr)))
+ return NULL;
- return NULL;
+ page = vmalloc_to_page(addr);
+ if (unlikely(!page))
+ return NULL;
+
+ return page->area;
}
/**
@@ -1536,6 +1539,7 @@ 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);
}
@@ -1744,6 +1748,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
const void *caller)
{
struct vm_struct *area;
+ unsigned int i;
void *addr;
unsigned long real_size = size;
@@ -1769,6 +1774,9 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
kmemleak_vmalloc(area, size, gfp_mask);
+ for (i = 0; i < area->nr_pages; i++)
+ area->pages[i]->area = area;
+
return addr;
fail:
--
2.14.1
Add basic self-test functionality for pmalloc.
Signed-off-by: Igor Stoppa <[email protected]>
---
mm/Kconfig | 9 ++++++++
mm/Makefile | 1 +
mm/pmalloc-selftest.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++
mm/pmalloc-selftest.h | 24 +++++++++++++++++++
mm/pmalloc.c | 2 ++
5 files changed, 100 insertions(+)
create mode 100644 mm/pmalloc-selftest.c
create mode 100644 mm/pmalloc-selftest.h
diff --git a/mm/Kconfig b/mm/Kconfig
index be578fbdce6d..098aefef78b1 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -766,3 +766,12 @@ config PROTECTABLE_MEMORY
depends on ARCH_HAS_SET_MEMORY
select GENERIC_ALLOCATOR
default y
+
+config PROTECTABLE_MEMORY_SELFTEST
+ bool "Run self test for pmalloc memory allocator"
+ 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..f7bbbfde6967 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_PROTECTABLE_MEMORY_SELFTEST) += pmalloc-selftest.o
obj-$(CONFIG_KSM) += ksm.o
obj-$(CONFIG_PAGE_POISONING) += page_poison.o
obj-$(CONFIG_SLAB) += slab.o
diff --git a/mm/pmalloc-selftest.c b/mm/pmalloc-selftest.c
new file mode 100644
index 000000000000..97ba52d17f69
--- /dev/null
+++ b/mm/pmalloc-selftest.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * pmalloc-selftest.c
+ *
+ * (C) Copyright 2018 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+#include <linux/pmalloc.h>
+#include <linux/mm.h>
+
+#include "pmalloc-selftest.h"
+
+#define SIZE_1 (PAGE_SIZE * 3)
+#define SIZE_2 1000
+
+#define validate_alloc(expected, variable, size) \
+ pr_notice("must be " expected ": %s", \
+ is_pmalloc_object(variable, size) > 0 ? "ok" : "no")
+
+#define is_alloc_ok(variable, size) \
+ validate_alloc("ok", variable, size)
+
+#define is_alloc_no(variable, size) \
+ validate_alloc("no", variable, size)
+
+void pmalloc_selftest(void)
+{
+ struct gen_pool *pool_unprot;
+ struct gen_pool *pool_prot;
+ void *var_prot, *var_unprot, *var_vmall;
+
+ pr_notice("pmalloc self-test");
+ pool_unprot = pmalloc_create_pool("unprotected", 0);
+ pool_prot = pmalloc_create_pool("protected", 0);
+ BUG_ON(!(pool_unprot && pool_prot));
+
+ 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);
+ is_alloc_ok(var_unprot, 10);
+ is_alloc_ok(var_unprot, SIZE_1);
+ is_alloc_ok(var_unprot, PAGE_SIZE);
+ is_alloc_no(var_unprot, SIZE_1 + 1);
+ 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
+ * destroyed is not protected, which is unusual and should happen
+ * on error paths only, where probably other warnings are already
+ * displayed.
+ */
+ pmalloc_destroy_pool(pool_unprot);
+
+ /* This must not cause WARNings */
+ pmalloc_destroy_pool(pool_prot);
+}
diff --git a/mm/pmalloc-selftest.h b/mm/pmalloc-selftest.h
new file mode 100644
index 000000000000..58a5a0cbec14
--- /dev/null
+++ b/mm/pmalloc-selftest.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * pmalloc-selftest.h
+ *
+ * (C) Copyright 2018 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <[email protected]>
+ */
+
+
+#ifndef __MM_PMALLOC_SELFTEST_H
+#define __MM_PMALLOC_SELFTEST_H
+
+
+#ifdef CONFIG_PROTECTABLE_MEMORY_SELFTEST
+
+void pmalloc_selftest(void);
+
+#else
+
+static inline void pmalloc_selftest(void){};
+
+#endif
+
+#endif
diff --git a/mm/pmalloc.c b/mm/pmalloc.c
index abddba90a9f6..eb445c574b19 100644
--- a/mm/pmalloc.c
+++ b/mm/pmalloc.c
@@ -22,6 +22,7 @@
#include <asm/page.h>
#include <linux/pmalloc.h>
+#include "pmalloc-selftest.h"
/*
* pmalloc_data contains the data specific to a pmalloc pool,
* in a format compatible with the design of gen_alloc.
@@ -494,6 +495,7 @@ static int __init pmalloc_late_init(void)
}
}
mutex_unlock(&pmalloc_mutex);
+ pmalloc_selftest();
return 0;
}
late_initcall(pmalloc_late_init);
--
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 | 114 +++++++++++++++++++++++++++++++++++++
2 files changed, 115 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..d9725870444e
--- /dev/null
+++ b/Documentation/core-api/pmalloc.rst
@@ -0,0 +1,114 @@
+.. 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.
+
+- Before destroying a pool, all the memory allocated from it must be
+ released.
+
+- 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
On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
> 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.
This series came up in discussions with Dave Chinner (and Matthew
Wilcox, already part of the discussion, and others) at LCA. I wonder
if XFS would make a good initial user of this, as it could allocate
all the function pointers and other const information about a
superblock in pmalloc(), keeping it separate from the R/W portions?
Could other filesystems do similar things?
Do you have other immediate users in mind for pmalloc? Adding those to
the series could really help both define the API and clarify the
usage.
-Kees
>
> 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 v15:
> [http://www.openwall.com/lists/kernel-hardening/2018/02/11/4]
>
> - Fixed remaining broken comments
> - Fixed remaining broken "Returns" instead of "Return:" in kernel-doc
> - Converted "Return:" values to lists
> - Fixed SPDX license statements
>
> Igor Stoppa (6):
> genalloc: track beginning of allocations
> genalloc: selftest
> struct page: add field for vm_struct
> Protectable Memory
> Pmalloc: self-test
> Documentation for Pmalloc
>
> Documentation/core-api/index.rst | 1 +
> Documentation/core-api/pmalloc.rst | 114 +++++++
> include/linux/genalloc-selftest.h | 26 ++
> include/linux/genalloc.h | 7 +-
> include/linux/mm_types.h | 1 +
> include/linux/pmalloc.h | 242 ++++++++++++++
> include/linux/vmalloc.h | 1 +
> init/main.c | 2 +
> lib/Kconfig | 15 +
> lib/Makefile | 1 +
> lib/genalloc-selftest.c | 400 ++++++++++++++++++++++
> lib/genalloc.c | 658 +++++++++++++++++++++++++++----------
> mm/Kconfig | 15 +
> mm/Makefile | 2 +
> mm/pmalloc-selftest.c | 64 ++++
> mm/pmalloc-selftest.h | 24 ++
> mm/pmalloc.c | 501 ++++++++++++++++++++++++++++
> mm/usercopy.c | 33 ++
> mm/vmalloc.c | 18 +-
> 19 files changed, 1950 insertions(+), 175 deletions(-)
> create mode 100644 Documentation/core-api/pmalloc.rst
> create mode 100644 include/linux/genalloc-selftest.h
> create mode 100644 include/linux/pmalloc.h
> create mode 100644 lib/genalloc-selftest.c
> create mode 100644 mm/pmalloc-selftest.c
> create mode 100644 mm/pmalloc-selftest.h
> create mode 100644 mm/pmalloc.c
>
> --
> 2.14.1
>
--
Kees Cook
Pixel Security
On Mon, Feb 12, 2018 at 8:53 AM, Igor Stoppa <[email protected]> wrote:
> Add basic self-test functionality for pmalloc.
>
> Signed-off-by: Igor Stoppa <[email protected]>
> ---
> mm/Kconfig | 9 ++++++++
> mm/Makefile | 1 +
> mm/pmalloc-selftest.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++
> mm/pmalloc-selftest.h | 24 +++++++++++++++++++
> mm/pmalloc.c | 2 ++
> 5 files changed, 100 insertions(+)
> create mode 100644 mm/pmalloc-selftest.c
> create mode 100644 mm/pmalloc-selftest.h
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index be578fbdce6d..098aefef78b1 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -766,3 +766,12 @@ config PROTECTABLE_MEMORY
> depends on ARCH_HAS_SET_MEMORY
> select GENERIC_ALLOCATOR
> default y
> +
> +config PROTECTABLE_MEMORY_SELFTEST
> + bool "Run self test for pmalloc memory allocator"
> + 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..f7bbbfde6967 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_PROTECTABLE_MEMORY_SELFTEST) += pmalloc-selftest.o
Nit: self-test modules are traditionally named "test_$thing.o"
(outside of the tools/ directory).
> obj-$(CONFIG_KSM) += ksm.o
> obj-$(CONFIG_PAGE_POISONING) += page_poison.o
> obj-$(CONFIG_SLAB) += slab.o
> diff --git a/mm/pmalloc-selftest.c b/mm/pmalloc-selftest.c
> new file mode 100644
> index 000000000000..97ba52d17f69
> --- /dev/null
> +++ b/mm/pmalloc-selftest.c
> @@ -0,0 +1,64 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * pmalloc-selftest.c
> + *
> + * (C) Copyright 2018 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <[email protected]>
> + */
> +
> +#include <linux/pmalloc.h>
> +#include <linux/mm.h>
> +
> +#include "pmalloc-selftest.h"
> +
> +#define SIZE_1 (PAGE_SIZE * 3)
> +#define SIZE_2 1000
> +
> +#define validate_alloc(expected, variable, size) \
> + pr_notice("must be " expected ": %s", \
> + is_pmalloc_object(variable, size) > 0 ? "ok" : "no")
> +
> +#define is_alloc_ok(variable, size) \
> + validate_alloc("ok", variable, size)
> +
> +#define is_alloc_no(variable, size) \
> + validate_alloc("no", variable, size)
> +
> +void pmalloc_selftest(void)
> +{
> + struct gen_pool *pool_unprot;
> + struct gen_pool *pool_prot;
> + void *var_prot, *var_unprot, *var_vmall;
> +
> + pr_notice("pmalloc self-test");
> + pool_unprot = pmalloc_create_pool("unprotected", 0);
> + pool_prot = pmalloc_create_pool("protected", 0);
> + BUG_ON(!(pool_unprot && pool_prot));
> +
> + 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);
> + is_alloc_ok(var_unprot, 10);
> + is_alloc_ok(var_unprot, SIZE_1);
> + is_alloc_ok(var_unprot, PAGE_SIZE);
> + is_alloc_no(var_unprot, SIZE_1 + 1);
> + 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
> + * destroyed is not protected, which is unusual and should happen
> + * on error paths only, where probably other warnings are already
> + * displayed.
> + */
> + pmalloc_destroy_pool(pool_unprot);
> +
> + /* This must not cause WARNings */
> + pmalloc_destroy_pool(pool_prot);
> +}
I wonder if lkdtm should grow a test too, to validate the RO-ness of
the allocations at the right time in API usage?
Otherwise, yay! Selftests!
-Kees
> diff --git a/mm/pmalloc-selftest.h b/mm/pmalloc-selftest.h
> new file mode 100644
> index 000000000000..58a5a0cbec14
> --- /dev/null
> +++ b/mm/pmalloc-selftest.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * pmalloc-selftest.h
> + *
> + * (C) Copyright 2018 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <[email protected]>
> + */
> +
> +
> +#ifndef __MM_PMALLOC_SELFTEST_H
> +#define __MM_PMALLOC_SELFTEST_H
> +
> +
> +#ifdef CONFIG_PROTECTABLE_MEMORY_SELFTEST
> +
> +void pmalloc_selftest(void);
> +
> +#else
> +
> +static inline void pmalloc_selftest(void){};
> +
> +#endif
> +
> +#endif
> diff --git a/mm/pmalloc.c b/mm/pmalloc.c
> index abddba90a9f6..eb445c574b19 100644
> --- a/mm/pmalloc.c
> +++ b/mm/pmalloc.c
> @@ -22,6 +22,7 @@
> #include <asm/page.h>
>
> #include <linux/pmalloc.h>
> +#include "pmalloc-selftest.h"
> /*
> * pmalloc_data contains the data specific to a pmalloc pool,
> * in a format compatible with the design of gen_alloc.
> @@ -494,6 +495,7 @@ static int __init pmalloc_late_init(void)
> }
> }
> mutex_unlock(&pmalloc_mutex);
> + pmalloc_selftest();
> return 0;
> }
> late_initcall(pmalloc_late_init);
> --
> 2.14.1
>
--
Kees Cook
Pixel Security
On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
> 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.
>
> Signed-off-by: Igor Stoppa <[email protected]>
> ---
> include/linux/genalloc-selftest.h | 26 +++
> init/main.c | 2 +
> lib/Kconfig | 15 ++
> lib/Makefile | 1 +
> lib/genalloc-selftest.c | 400 ++++++++++++++++++++++++++++++++++++++
Nit: make this test_genalloc.c instead.
> 5 files changed, 444 insertions(+)
> create mode 100644 include/linux/genalloc-selftest.h
> create mode 100644 lib/genalloc-selftest.c
>
> diff --git a/include/linux/genalloc-selftest.h b/include/linux/genalloc-selftest.h
> new file mode 100644
> index 000000000000..e0ac8f963abc
> --- /dev/null
> +++ b/include/linux/genalloc-selftest.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * genalloc-selftest.h
> + *
> + * (C) Copyright 2017 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <[email protected]>
> + */
> +
> +
> +#ifndef __LINUX_GENALLOC_SELFTEST_H
> +#define __LINUX_GENALLOC_SELFTEST_H
> +
> +
> +#ifdef CONFIG_GENERIC_ALLOCATOR_SELFTEST
> +
> +#include <linux/genalloc.h>
> +
> +void genalloc_selftest(void);
> +
> +#else
> +
> +static inline void genalloc_selftest(void){};
> +
> +#endif
> +
> +#endif
> diff --git a/init/main.c b/init/main.c
> index a8100b954839..fb844aa3eb8c 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -89,6 +89,7 @@
> #include <linux/io.h>
> #include <linux/cache.h>
> #include <linux/rodata_test.h>
> +#include <linux/genalloc-selftest.h>
>
> #include <asm/io.h>
> #include <asm/bugs.h>
> @@ -660,6 +661,7 @@ asmlinkage __visible void __init start_kernel(void)
> */
> mem_encrypt_init();
>
> + genalloc_selftest();
I wonder if it's possible to make this module-loadable instead? That
way it could be built and tested separately. Regardless, I love
gaining more internal selftests, this is great. :)
> #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..0d526c004e81 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -287,6 +287,21 @@ config DECOMPRESS_LZ4
> config GENERIC_ALLOCATOR
> bool
>
> +config GENERIC_ALLOCATOR_SELFTEST
Like the other lib/test_*.c targets, I'd call this 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 GENERIC_ALLOCATOR_SELFTEST_VERBOSE
> + bool "make the genalloc tester more verbose"
> + default n
> + select GENERIC_ALLOCATOR_SELFTEST
> + 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..fadb30abde08 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-$(CONFIG_GENERIC_ALLOCATOR_SELFTEST) += genalloc-selftest.o
>
> obj-$(CONFIG_842_COMPRESS) += 842/
> obj-$(CONFIG_842_DECOMPRESS) += 842/
> diff --git a/lib/genalloc-selftest.c b/lib/genalloc-selftest.c
> new file mode 100644
> index 000000000000..e86be22c5512
> --- /dev/null
> +++ b/lib/genalloc-selftest.c
> @@ -0,0 +1,400 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * genalloc-selftest.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/genalloc-selftest.h>
> +/*
> + * 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_GENERIC_ALLOCATOR_SELFTEST_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));
There's been a lot recently on BUG vs WARN. It does seem crazy to not
BUG for an allocator selftest, but if we can avoid it, we should.
Also, I wonder if it might make sense to split this series up a little
more, as in:
1/n: add genalloc selftest
2/n: update bitmaps
3/n: add/change bitmap tests to selftest
Maybe I'm over-thinking it, but the great thing about this self test
is that it's checking much more than just the bitmap changes you're
making, and that can be used to "prove" that genalloc continues to
work after the changes (i.e. the selftest passes before the changes,
and after, rather than just after).
> +}
> +
> +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 genalloc_selftest(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
>
-Kees
--
Kees Cook
Pixel Security
On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
> @@ -738,14 +1031,16 @@ 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)
I wonder if this might be more readable by splitting the kernel-doc
changes from the bitmap changes? I.e. fix all the kernel-doc in one
patch, and in the following, make the bitmap changes. Maybe it's such
a small part that it doesn't matter, though?
-Kees
--
Kees Cook
Pixel Security
On Mon, Feb 12, 2018 at 03:32:36PM -0800, Kees Cook wrote:
> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
> > 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.
>
> This series came up in discussions with Dave Chinner (and Matthew
> Wilcox, already part of the discussion, and others) at LCA. I wonder
> if XFS would make a good initial user of this, as it could allocate
> all the function pointers and other const information about a
> superblock in pmalloc(), keeping it separate from the R/W portions?
> Could other filesystems do similar things?
I wasn't cc'd on this patchset, (please use [email protected] for
future postings) so I can't really say anything about it right
now. My interest for XFS was that we have a fair amount of static
data in XFS that we set up at mount time and it never gets modified
after that. I'm not so worried about VFS level objects (that's a
much more complex issue) but there is a lot of low hanging fruit in
the XFS structures we could convert to write-once structures.
Cheers,
Dave.
--
Dave Chinner
[email protected]
On 13/02/18 01:43, Kees Cook wrote:
> On Mon, Feb 12, 2018 at 8:53 AM, Igor Stoppa <[email protected]> wrote:
[...]
>> +obj-$(CONFIG_PROTECTABLE_MEMORY_SELFTEST) += pmalloc-selftest.o
>
> Nit: self-test modules are traditionally named "test_$thing.o"
> (outside of the tools/ directory).
ok
[...]
> I wonder if lkdtm should grow a test too, to validate the RO-ness of
> the allocations at the right time in API usage?
sorry for being dense ... are you proposing that I do something to
lkdtm_rodata.c ? An example would probably help me understand.
--
igor
On 13/02/18 01:50, Kees Cook wrote:
> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
[...]
>> lib/genalloc-selftest.c | 400 ++++++++++++++++++++++++++++++++++++++
>
> Nit: make this test_genalloc.c instead.
ok
[...]
>> + genalloc_selftest();
>
> I wonder if it's possible to make this module-loadable instead? That
> way it could be built and tested separately.
In my case modules are not an option.
Of course it could be still built in, but what is the real gain?
[...]
>> +config GENERIC_ALLOCATOR_SELFTEST
>
> Like the other lib/test_*.c targets, I'd call this TEST_GENERIC_ALLOCATOR.
ok
[...]
>> + BUG_ON(compare_bitmaps(pool, action->pattern));
>
> There's been a lot recently on BUG vs WARN. It does seem crazy to not
> BUG for an allocator selftest, but if we can avoid it, we should.
If this fails, I would expect that memory corruption is almost guaranteed.
Do we really want to allow the boot to continue, possibly mounting a
filesystem, only to corrupt it? It seems very dangerous.
> Also, I wonder if it might make sense to split this series up a little
> more, as in:
>
> 1/n: add genalloc selftest
> 2/n: update bitmaps
> 3/n: add/change bitmap tests to selftest
>
> Maybe I'm over-thinking it, but the great thing about this self test
> is that it's checking much more than just the bitmap changes you're
> making, and that can be used to "prove" that genalloc continues to
> work after the changes (i.e. the selftest passes before the changes,
> and after, rather than just after).
If I really have to ... but to me the evidence that the changes to the
bitmaps do really work is already provided by the bitmap patch itself.
Since the patch doesn't remove the parameter indicating the space to be
freed, it can actually compare what the kernel passes to it vs. what it
thinks the space should be.
If the values were different, it would complain, but it doesn't ...
Isn't that even stronger evidence that the bitmap changes work as expected?
(eventually the parameter can be removed, but I intentionally left it,
for facilitating the merge)
--
igor
On 13/02/18 01:52, Kees Cook wrote:
> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
>> @@ -738,14 +1031,16 @@ 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)
>
> I wonder if this might be more readable by splitting the kernel-doc
> changes from the bitmap changes? I.e. fix all the kernel-doc in one
> patch, and in the following, make the bitmap changes. Maybe it's such
> a small part that it doesn't matter, though?
I had the same thought, but then I would have made most of the kerneldoc
changes to something that would be altered by the following patch,
because it would have made little sense to fix only those parts that
would have survived.
If it is really a problem to keep them together, I could put these
changes in a following patch. Would that be ok?
--
igor
On 20/02/18 03:21, Dave Chinner wrote:
> On Mon, Feb 12, 2018 at 03:32:36PM -0800, Kees Cook wrote:
>> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
>>> 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.
>>
>> This series came up in discussions with Dave Chinner (and Matthew
>> Wilcox, already part of the discussion, and others) at LCA. I wonder
>> if XFS would make a good initial user of this, as it could allocate
>> all the function pointers and other const information about a
>> superblock in pmalloc(), keeping it separate from the R/W portions?
>> Could other filesystems do similar things?
>
> I wasn't cc'd on this patchset, (please use [email protected] for
> future postings)
Apologies, somehow I didn't realize that I should have put you too in
CC. It will be fixed at the next iteration.
> so I can't really say anything about it right
> now. My interest for XFS was that we have a fair amount of static
> data in XFS that we set up at mount time and it never gets modified
> after that.
This is the typical use case I had in mind, although it requires a
conversion.
Ex:
before:
static int a;
void set_a(void)
{
a = 4;
}
after:
static int *a __ro_after_init;
struct gen_pool *pool;
void init_a(void)
{
pool = pmalloc_create_pool("pool", 0);
a = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL);
}
void set_a(void)
{
*a = 4;
pmalloc_protect_pool(pool);
}
> I'm not so worried about VFS level objects (that's a
> much more complex issue) but there is a lot of low hanging fruit in
> the XFS structures we could convert to write-once structures.
I'd be interested to have your review of the pmalloc API, if you think
something is missing, once I send out the next revision.
--
igor
On Tue, Feb 20, 2018 at 08:03:49PM +0200, Igor Stoppa wrote:
>
>
> On 20/02/18 03:21, Dave Chinner wrote:
> > On Mon, Feb 12, 2018 at 03:32:36PM -0800, Kees Cook wrote:
> >> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
> >>> 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.
> >>
> >> This series came up in discussions with Dave Chinner (and Matthew
> >> Wilcox, already part of the discussion, and others) at LCA. I wonder
> >> if XFS would make a good initial user of this, as it could allocate
> >> all the function pointers and other const information about a
> >> superblock in pmalloc(), keeping it separate from the R/W portions?
> >> Could other filesystems do similar things?
> >
> > I wasn't cc'd on this patchset, (please use [email protected] for
> > future postings)
>
> Apologies, somehow I didn't realize that I should have put you too in
> CC. It will be fixed at the next iteration.
No worries, If you weren't at LCA, you wouldn't have known :P
> > so I can't really say anything about it right
> > now. My interest for XFS was that we have a fair amount of static
> > data in XFS that we set up at mount time and it never gets modified
> > after that.
>
> This is the typical use case I had in mind, although it requires a
> conversion.
> Ex:
>
> before:
>
> static int a;
>
>
> void set_a(void)
> {
> a = 4;
> }
>
>
>
> after:
>
> static int *a __ro_after_init;
> struct gen_pool *pool;
>
> void init_a(void)
> {
> pool = pmalloc_create_pool("pool", 0);
> a = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL);
> }
>
> void set_a(void)
> {
> *a = 4;
> pmalloc_protect_pool(pool);
> }
Yeah, that's kinda what I figured. I'm guessing that I treat a pool
just like a normal heap allocation, but then when all the objects I
need to allocate are fully initialised, then I write protect the
pool? i.e. the API isn't using an object-based protection scope?
FWIW, I'm not wanting to use it to replace static variables. All the
structures are dynamically allocated right now, and get assigned to
other dynamically allocated pointers. I'd likely split the current
structures into a "ro after init" structure and rw structure, so
how does the "__ro_after_init" attribute work in that case? Is it
something like this?
struct xfs_mount {
struct xfs_mount_ro{
.......
} *ro __ro_after_init;
......
Also, what compile time checks are in place to catch writes to
ro structure members? Is sparse going to be able to check this sort
of thing, like is does with endian-specific variables?
> I'd be interested to have your review of the pmalloc API, if you think
> something is missing, once I send out the next revision.
I'll look at it in more depth when it comes past again. :P
Cheers,
Dave.
--
Dave Chinner
[email protected]
On Wed, Feb 21, 2018 at 08:36:04AM +1100, Dave Chinner wrote:
> FWIW, I'm not wanting to use it to replace static variables. All the
> structures are dynamically allocated right now, and get assigned to
> other dynamically allocated pointers. I'd likely split the current
> structures into a "ro after init" structure and rw structure, so
> how does the "__ro_after_init" attribute work in that case? Is it
> something like this?
>
> struct xfs_mount {
> struct xfs_mount_ro{
> .......
> } *ro __ro_after_init;
> ......
No, you'd do:
struct xfs_mount_ro {
[...]
};
struct xfs_mount {
const struct xfs_mount_ro *ro;
[...]
};
We can't do protection on less than a page boundary, so you can't embed
a ro struct inside a rw struct.
> Also, what compile time checks are in place to catch writes to
> ro structure members? Is sparse going to be able to check this sort
> of thing, like is does with endian-specific variables?
Just labelling the pointer const should be enough for the compiler to
catch unintended writes.
> > I'd be interested to have your review of the pmalloc API, if you think
> > something is missing, once I send out the next revision.
>
> I'll look at it in more depth when it comes past again. :P
I think the key question is whether you want a slab-style interface
or whether you want a kmalloc-style interface. I'd been assuming
the former, but Igor has implemented the latter already.
On Tue, Feb 20, 2018 at 03:56:00PM -0800, Matthew Wilcox wrote:
> On Wed, Feb 21, 2018 at 08:36:04AM +1100, Dave Chinner wrote:
> > FWIW, I'm not wanting to use it to replace static variables. All the
> > structures are dynamically allocated right now, and get assigned to
> > other dynamically allocated pointers. I'd likely split the current
> > structures into a "ro after init" structure and rw structure, so
> > how does the "__ro_after_init" attribute work in that case? Is it
> > something like this?
> >
> > struct xfs_mount {
> > struct xfs_mount_ro{
> > .......
> > } *ro __ro_after_init;
^^^^^^^^
pointer, not embedded structure....
> > ......
>
> No, you'd do:
>
> struct xfs_mount_ro {
> [...]
> };
>
> struct xfs_mount {
> const struct xfs_mount_ro *ro;
> [...]
> };
.... so that's pretty much the same thing :P
> > Also, what compile time checks are in place to catch writes to
> > ro structure members? Is sparse going to be able to check this sort
> > of thing, like is does with endian-specific variables?
>
> Just labelling the pointer const should be enough for the compiler to
> catch unintended writes.
Ok.
> > > I'd be interested to have your review of the pmalloc API, if you think
> > > something is missing, once I send out the next revision.
> >
> > I'll look at it in more depth when it comes past again. :P
>
> I think the key question is whether you want a slab-style interface
> or whether you want a kmalloc-style interface. I'd been assuming
> the former, but Igor has implemented the latter already.
Slabs are rally only useful when you have lots of a specific type of
object. I'm concerned mostly about one-off per-mount point
structures, of which there are relatively few. A heap-like pool per
mount is fine for this.
Cheers,
Dave.
--
Dave Chinner
[email protected]
On 21/02/18 03:36, Dave Chinner wrote:
> On Tue, Feb 20, 2018 at 03:56:00PM -0800, Matthew Wilcox wrote:
>> On Wed, Feb 21, 2018 at 08:36:04AM +1100, Dave Chinner wrote:
>>> FWIW, I'm not wanting to use it to replace static variables. All the
>>> structures are dynamically allocated right now, and get assigned to
>>> other dynamically allocated pointers. I'd likely split the current
>>> structures into a "ro after init"
I would prefer to use a different terminology, because, if I have
understood the use case, this is not exactly the same as __ro_after_init
So, this is my understanding:
* "const" needs to be known at link time - there might be some
adjustments later on, ex: patching of "const" pointers, after relocation
has taken place - I am assuming we are not planning to patch const data
The compiler can perform whatever optimization it feels like and it is
allowed to do, on this.
* __ro_after_init is almost the same as a const, from a r/w perspective,
but it will become effectively read_only after the completion of the
init phase. The compiler cannot use it in any way to detect errors,
AFAIK. The system will just generate a runtime error is someone tries to
alter some __ro_after_init data, when it's read-only.
The only trick available is to use, after the protection, a different
type of handle, const.
* pmalloc pools can be protected (hence the "p") at any time, but they
start as r/w. Also, they cannot be declared statically.
* data which is either const or __ro_after_init is placed into specific
sections (on arm64 it's actually the same) and its pages are then marked
as read-only.
>>> structure and rw structure, so
>>> how does the "__ro_after_init" attribute work in that case? Is it
>>> something like this?
>>>
>>> struct xfs_mount {
>>> struct xfs_mount_ro{
>>> .......
>>> } *ro __ro_after_init;
> ^^^^^^^^
>
> pointer, not embedded structure....
I doubt this would work, because I think it's not possible to put a
field of a structure into a separate section, afaik.
__ro_after_init would refer to the ro field, not to the memory it refers to.
>>> ......
>>
>> No, you'd do:
>>
>> struct xfs_mount_ro {
>> [...]
>> };
is this something that is readonly from the beginning and then shared
among mount points or is it specific to each mount point?
>> struct xfs_mount {
>> const struct xfs_mount_ro *ro;
>> [...]
>> };
>
> .... so that's pretty much the same thing :P
The "const" modifier is a nice way to catch errors through the compiler,
iff the ro data will not be initialized through this handle, when it's
still writable.
>>> Also, what compile time checks are in place to catch writes to
>>> ro structure members? Is sparse going to be able to check this sort
>>> of thing, like is does with endian-specific variables?
>>
>> Just labelling the pointer const should be enough for the compiler to
>> catch unintended writes.
>
> Ok.
yes, anyway the first one trying to alter it at run time, is in for some
surprise.
>>>> I'd be interested to have your review of the pmalloc API, if you think
>>>> something is missing, once I send out the next revision.
>>>
>>> I'll look at it in more depth when it comes past again. :P
>>
>> I think the key question is whether you want a slab-style interface
>> or whether you want a kmalloc-style interface. I'd been assuming
>> the former, but Igor has implemented the latter already.
>
> Slabs are rally only useful when you have lots of a specific type of
> object. I'm concerned mostly about one-off per-mount point
> structures, of which there are relatively few. A heap-like pool per
> mount is fine for this.
That was my same sentiment.
Actually it would be even possible to simulate caches with pools: each
pool supports a granularity parameter, during creation. One could have
multiple pools, each with different granularity, but it would probably
lead to a proliferation of pools.
Instead, I preferred to have pmalloc as a drop-in replacement for the
variants of k/v/kv malloc.
The only real issue was the - previous - inability of tracking the size
of an allocation, given its address, but that is taken care of by the
patch for the genalloc bitmap.
If I could have a pointer to a good candidate for the pmalloc treatment,
I could come up with a patch, to show how it could be done.
Then it might be easier to discuss if the API needs to be modified
and/or extended somehow.
--
igor
On Wed, Feb 21, 2018 at 11:56:22AM +0200, Igor Stoppa wrote:
> On 21/02/18 03:36, Dave Chinner wrote:
> > On Tue, Feb 20, 2018 at 03:56:00PM -0800, Matthew Wilcox wrote:
> >> On Wed, Feb 21, 2018 at 08:36:04AM +1100, Dave Chinner wrote:
> >>> FWIW, I'm not wanting to use it to replace static variables. All the
> >>> structures are dynamically allocated right now, and get assigned to
> >>> other dynamically allocated pointers. I'd likely split the current
> >>> structures into a "ro after init"
>
> I would prefer to use a different terminology, because, if I have
> understood the use case, this is not exactly the same as __ro_after_init
I want a dynamically allocated "write once" structure.
A "write once" structure is, conceptually, is exactly the same as
"ro after init". Implementation wise, it may be different to
"__ro_after_init", especially when compared to static/global
variables.
It seems lots of people get confused when discussing concepts vs
implementation... :)
> >>> ......
> >>
> >> No, you'd do:
> >>
> >> struct xfs_mount_ro {
> >> [...]
> >> };
>
> is this something that is readonly from the beginning and then shared
> among mount points or is it specific to each mount point?
It's dynamically allocated for each mount point, made read-only
before the mount completes and lives for the length of the mount
point.
> >> struct xfs_mount {
> >> const struct xfs_mount_ro *ro;
> >> [...]
> >> };
> >
> > .... so that's pretty much the same thing :P
>
> The "const" modifier is a nice way to catch errors through the compiler,
> iff the ro data will not be initialized through this handle, when it's
> still writable.
That's kinda implied by the const, isn't it? If we don't do it that
way, then the compiler will throw errors....
Cheers,
Dave.
--
Dave Chinner
[email protected]
On Tue, Feb 20, 2018 at 8:40 AM, Igor Stoppa <[email protected]> wrote:
>
> On 13/02/18 01:43, Kees Cook wrote:
>> On Mon, Feb 12, 2018 at 8:53 AM, Igor Stoppa <[email protected]> wrote:
>
> [...]
>
>>> +obj-$(CONFIG_PROTECTABLE_MEMORY_SELFTEST) += pmalloc-selftest.o
>>
>> Nit: self-test modules are traditionally named "test_$thing.o"
>> (outside of the tools/ directory).
>
> ok
>
> [...]
>
>> I wonder if lkdtm should grow a test too, to validate the RO-ness of
>> the allocations at the right time in API usage?
>
> sorry for being dense ... are you proposing that I do something to
> lkdtm_rodata.c ? An example would probably help me understand.
It would likely live in lkdtm_perms.c (or maybe lkdtm_heap.c). Namely,
use the pmalloc API and then attempt to write to a read-only variable
in the pmalloc region (to prove that the permission adjustment
actually happened). Likely a good example is
lkdtm_WRITE_RO_AFTER_INIT().
-Kees
--
Kees Cook
Pixel Security
On Tue, Feb 20, 2018 at 8:59 AM, Igor Stoppa <[email protected]> wrote:
>
>
> On 13/02/18 01:50, Kees Cook wrote:
>> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
>
> [...]
>
>>> lib/genalloc-selftest.c | 400 ++++++++++++++++++++++++++++++++++++++
>>
>> Nit: make this test_genalloc.c instead.
>
> ok
>
> [...]
>
>>> + genalloc_selftest();
>>
>> I wonder if it's possible to make this module-loadable instead? That
>> way it could be built and tested separately.
>
> In my case modules are not an option.
> Of course it could be still built in, but what is the real gain?
The gain for it being a module is that it can be loaded and tested
separately from the final kernel image and module collection. For
example, Chrome OS builds lots of debugging test modules but doesn't
include them on the final image. They're only used for testing, and
can be separate from the kernel and "production" modules.
> [...]
>
>>> + BUG_ON(compare_bitmaps(pool, action->pattern));
>>
>> There's been a lot recently on BUG vs WARN. It does seem crazy to not
>> BUG for an allocator selftest, but if we can avoid it, we should.
>
> If this fails, I would expect that memory corruption is almost guaranteed.
> Do we really want to allow the boot to continue, possibly mounting a
> filesystem, only to corrupt it? It seems very dangerous.
I would include the rationale in either a comment or the commit log.
BUG() tends to need to be very well justified these days.
>> Also, I wonder if it might make sense to split this series up a little
>> more, as in:
>>
>> 1/n: add genalloc selftest
>> 2/n: update bitmaps
>> 3/n: add/change bitmap tests to selftest
>>
>> Maybe I'm over-thinking it, but the great thing about this self test
>> is that it's checking much more than just the bitmap changes you're
>> making, and that can be used to "prove" that genalloc continues to
>> work after the changes (i.e. the selftest passes before the changes,
>> and after, rather than just after).
>
> If I really have to ... but to me the evidence that the changes to the
> bitmaps do really work is already provided by the bitmap patch itself.
>
> Since the patch doesn't remove the parameter indicating the space to be
> freed, it can actually compare what the kernel passes to it vs. what it
> thinks the space should be.
>
> If the values were different, it would complain, but it doesn't ...
> Isn't that even stronger evidence that the bitmap changes work as expected?
>
> (eventually the parameter can be removed, but I intentionally left it,
> for facilitating the merge)
I'll leave it up to the -mm folks, but that was just my thought.
-Kees
--
Kees Cook
Pixel Security
On Tue, Feb 20, 2018 at 9:07 AM, Igor Stoppa <[email protected]> wrote:
> On 13/02/18 01:52, Kees Cook wrote:
>> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
>>> @@ -738,14 +1031,16 @@ 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)
>>
>> I wonder if this might be more readable by splitting the kernel-doc
>> changes from the bitmap changes? I.e. fix all the kernel-doc in one
>> patch, and in the following, make the bitmap changes. Maybe it's such
>> a small part that it doesn't matter, though?
>
> I had the same thought, but then I would have made most of the kerneldoc
> changes to something that would be altered by the following patch,
> because it would have made little sense to fix only those parts that
> would have survived.
>
> If it is really a problem to keep them together, I could put these
> changes in a following patch. Would that be ok?
Hmmm... I think keeping it as-is would be better than a trailing
docs-only patch. Maybe Jon has an opinion?
-Kees
--
Kees Cook
Pixel Security
On Wed, 21 Feb 2018 14:29:06 -0800
Kees Cook <[email protected]> wrote:
> >> I wonder if this might be more readable by splitting the kernel-doc
> >> changes from the bitmap changes? I.e. fix all the kernel-doc in one
> >> patch, and in the following, make the bitmap changes. Maybe it's such
> >> a small part that it doesn't matter, though?
> >
> > I had the same thought, but then I would have made most of the kerneldoc
> > changes to something that would be altered by the following patch,
> > because it would have made little sense to fix only those parts that
> > would have survived.
> >
> > If it is really a problem to keep them together, I could put these
> > changes in a following patch. Would that be ok?
>
> Hmmm... I think keeping it as-is would be better than a trailing
> docs-only patch. Maybe Jon has an opinion?
I would be inclined to agree. Putting docs changes with the associated
code changes helps to document the patch itself, among other things. I
wouldn't split them up.
jon
On 21/02/18 23:36, Dave Chinner wrote:
> On Wed, Feb 21, 2018 at 11:56:22AM +0200, Igor Stoppa wrote:
[...]
> It seems lots of people get confused when discussing concepts vs
> implementation... :)
IMHO, if possible, it's better to use unambiguous terms at every point.
__ro_after_init is already taken :-P
In this specific case, I wanted to be absolutely sure I understood
correctly what you need. I think I have now, thanks.
>> is this something that is readonly from the beginning and then shared
>> among mount points or is it specific to each mount point?
>
> It's dynamically allocated for each mount point, made read-only
> before the mount completes and lives for the length of the mount
> point.
ok. And destroyed when the mount point is unmounted, I expect.
[...]
>> The "const" modifier is a nice way to catch errors through the compiler,
>> iff the ro data will not be initialized through this handle, when it's
>> still writable.
>
> That's kinda implied by the const, isn't it? If we don't do it that
> way, then the compiler will throw errors....
I might be splitting the hair, but since I'm advertising something I
worte, I don't want to look like a peddler of snake oil, in hindsight :-P
To clarify my previous comment:
* const can mean the world to the compiler, but that doesn't
automatically translate into write-protected memory, yet I do appreciate
the advantage of teaching the compiler what should not be altered.
And I have nothing against doing it.
* even if some handle will be const, it still needs to be aliased to
some other pointer that is not const, at the beginning, because it must
be initialized and it's anyway writable. So, this cannot be avoided.
--
igor
On 22/02/18 00:24, Kees Cook wrote:
> On Tue, Feb 20, 2018 at 8:40 AM, Igor Stoppa <[email protected]> wrote:
[...]
>> sorry for being dense ... are you proposing that I do something to
>> lkdtm_rodata.c ? An example would probably help me understand.
>
> It would likely live in lkdtm_perms.c (or maybe lkdtm_heap.c). Namely,
> use the pmalloc API and then attempt to write to a read-only variable
> in the pmalloc region (to prove that the permission adjustment
> actually happened). Likely a good example is
> lkdtm_WRITE_RO_AFTER_INIT().
ok, thanks for the explanation, I will do it
--
igor
On 22/02/18 00:28, Kees Cook wrote:
> On Tue, Feb 20, 2018 at 8:59 AM, Igor Stoppa <[email protected]> wrote:
>>
>>
>> On 13/02/18 01:50, Kees Cook wrote:
>>> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
[...]
>>>> + genalloc_selftest();
>>>
>>> I wonder if it's possible to make this module-loadable instead? That
>>> way it could be built and tested separately.
>>
>> In my case modules are not an option.
>> Of course it could be still built in, but what is the real gain?
>
> The gain for it being a module is that it can be loaded and tested
> separately from the final kernel image and module collection. For
> example, Chrome OS builds lots of debugging test modules but doesn't
> include them on the final image. They're only used for testing, and
> can be separate from the kernel and "production" modules.
ok
>
>> [...]
>>
>>>> + BUG_ON(compare_bitmaps(pool, action->pattern));
>>>
>>> There's been a lot recently on BUG vs WARN. It does seem crazy to not
>>> BUG for an allocator selftest, but if we can avoid it, we should.
>>
>> If this fails, I would expect that memory corruption is almost guaranteed.
>> Do we really want to allow the boot to continue, possibly mounting a
>> filesystem, only to corrupt it? It seems very dangerous.
>
> I would include the rationale in either a comment or the commit log.
> BUG() tends to need to be very well justified these days.
ok
>
>>> Also, I wonder if it might make sense to split this series up a little
>>> more, as in:
>>>
>>> 1/n: add genalloc selftest
>>> 2/n: update bitmaps
>>> 3/n: add/change bitmap tests to selftest
[...]
> I'll leave it up to the -mm folks, but that was just my thought.
The reasons why I have doubts about your proposal are:
1) leaving 2/n and 3/n separate mean that the selftest could be broken,
if one does bisections with selftest enabled
2) since I would need to change the selftest, to make it work with the
updated bitmap, it would not really prove that the change is correct.
If there was a selftest that can work without changes, after the bitmap
update, I would definitely agree to introduce it first.
OTOH, as I wrote, the bitmap patch itself is already introducing
verification of the calculated value (from the bitmap) against the
provided value (from the call parameters).
This, unfortunately, cannot be split, because it still relies on the
"find end of the allocation" capability introduced by the very same patch.
Anyway, putting aside concerns about the verification of the correctness
of the patch, I still see point #1 as a problem: breaking bisectability.
Or did I not understand correctly how this works?
--
igor
On 22/02/18 11:14, Igor Stoppa wrote:
>
>
> On 22/02/18 00:28, Kees Cook wrote:
>> On Tue, Feb 20, 2018 at 8:59 AM, Igor Stoppa <[email protected]> wrote:
>>>
>>>
>>> On 13/02/18 01:50, Kees Cook wrote:
>>>> On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <[email protected]> wrote:
>
> [...]
>
>>>>> + genalloc_selftest();
>>>>
>>>> I wonder if it's possible to make this module-loadable instead? That
>>>> way it could be built and tested separately.
>>>
>>> In my case modules are not an option.
>>> Of course it could be still built in, but what is the real gain?
>>
>> The gain for it being a module is that it can be loaded and tested
>> separately from the final kernel image and module collection. For
>> example, Chrome OS builds lots of debugging test modules but doesn't
>> include them on the final image. They're only used for testing, and
>> can be separate from the kernel and "production" modules.
>
> ok
I started to turn this into a module, but after all it doesn't seem like
it would give any real advantage, compared to the current implementation.
This testing is meant to catch bugs in memory management as early as
possible in the boot phase, before users of genalloc start to fail in
mysterious ways.
This includes, but is not limited to: MCE on x86, uncached pages
provider on arm64, dma on arm.
Should genalloc fail, it's highly unlikely that the test rig would even
reach the point where it can load a module and run it, even if it is
located in initrd.
The test would not be run, precisely at the moment where its output
would be needed the most, leaving a crash log that is hard to debug
because of memory corruption.
I do not know how Chrome OS builds are organized, but I imagine that
probably there is a separate test build, where options like lockdep,
ubsan, etc. are enabled.
All options that cannot be left enabled in a production kernel, but are
very useful for sanity checks and require a separate build.
Genalloc testing should be added there, rather than in a module, imho.
--
igor