2014-11-19 01:44:33

by Yinghai Lu

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Subject: [PATCH 1/3] x86: Fix typo in mark_rodata_ro

In the comment, should use cleanup_highmap().
and also remove not needed cast for _brk_end, as it is
unsigned long.

Signed-off-by: Yinghai Lu <[email protected]>

---
arch/x86/mm/init_64.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -1145,9 +1145,9 @@ void mark_rodata_ro(void)
* of the PMD will remain mapped executable.
*
* Any PMD which was setup after the one which covers _brk_end
- * has been zapped already via cleanup_highmem().
+ * has been zapped already via cleanup_highmap().
*/
- all_end = roundup((unsigned long)_brk_end, PMD_SIZE);
+ all_end = roundup(_brk_end, PMD_SIZE);
set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT);

rodata_test();


2014-11-19 01:44:44

by Yinghai Lu

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Subject: [PATCH 2/3] x86, 64bit: add pfn_range_is_highmapped()

Need to use it to support holes in highmap when remove not
used range in highmap.

Signed-off-by: Yinghai Lu <[email protected]>

---
arch/x86/include/asm/pgtable_64.h | 2 ++
arch/x86/mm/init_64.c | 22 ++++++++++++++++++++++
arch/x86/mm/pageattr.c | 16 +---------------
3 files changed, 25 insertions(+), 15 deletions(-)

Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -378,6 +378,23 @@ void __init init_extra_mapping_uc(unsign
__init_extra_mapping(phys, size, _PAGE_CACHE_MODE_UC);
}

+/* three holes at most*/
+#define NR_RANGE 4
+static struct range pfn_highmapped[NR_RANGE];
+static int nr_pfn_highmapped;
+
+int pfn_range_is_highmapped(unsigned long start_pfn, unsigned long end_pfn)
+{
+ int i;
+
+ for (i = 0; i < nr_pfn_highmapped; i++)
+ if ((start_pfn >= pfn_highmapped[i].start) &&
+ (end_pfn <= pfn_highmapped[i].end))
+ return 1;
+
+ return 0;
+}
+
/*
* The head.S code sets up the kernel high mapping:
*
@@ -412,6 +429,11 @@ void __init cleanup_highmap(void)
if (vaddr < (unsigned long) _text || vaddr > end)
set_pmd(pmd, __pmd(0));
}
+
+ nr_pfn_highmapped = add_range(pfn_highmapped, NR_RANGE,
+ nr_pfn_highmapped,
+ __pa_symbol(_text) >> PAGE_SHIFT,
+ __pa_symbol(roundup(_brk_end, PMD_SIZE)) >> PAGE_SHIFT);
}

static unsigned long __meminit
Index: linux-2.6/arch/x86/mm/pageattr.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/pageattr.c
+++ linux-2.6/arch/x86/mm/pageattr.c
@@ -91,20 +91,6 @@ void arch_report_meminfo(struct seq_file
static inline void split_page_count(int level) { }
#endif

-#ifdef CONFIG_X86_64
-
-static inline unsigned long highmap_start_pfn(void)
-{
- return __pa_symbol(_text) >> PAGE_SHIFT;
-}
-
-static inline unsigned long highmap_end_pfn(void)
-{
- return __pa_symbol(roundup(_brk_end, PMD_SIZE)) >> PAGE_SHIFT;
-}
-
-#endif
-
#ifdef CONFIG_DEBUG_PAGEALLOC
# define debug_pagealloc 1
#else
@@ -1255,7 +1241,7 @@ static int cpa_process_alias(struct cpa_
* to touch the high mapped kernel as well:
*/
if (!within(vaddr, (unsigned long)_text, _brk_end) &&
- within(cpa->pfn, highmap_start_pfn(), highmap_end_pfn())) {
+ pfn_range_is_highmapped(cpa->pfn, 1)) {
unsigned long temp_cpa_vaddr = (cpa->pfn << PAGE_SHIFT) +
__START_KERNEL_map - phys_base;
alias_cpa = *cpa;
Index: linux-2.6/arch/x86/include/asm/pgtable_64.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/pgtable_64.h
+++ linux-2.6/arch/x86/include/asm/pgtable_64.h
@@ -167,6 +167,8 @@ static inline int pgd_large(pgd_t pgd) {
extern int kern_addr_valid(unsigned long addr);
extern void cleanup_highmap(void);

+int pfn_range_is_highmapped(unsigned long start_pfn, unsigned long end_pfn);
+
#define HAVE_ARCH_UNMAPPED_AREA
#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN

2014-11-19 01:44:51

by Yinghai Lu

[permalink] [raw]
Subject: [PATCH 3/4] x86, 64bit: remove highmap for not needed ranges

add cleanup_highmap_late to remove highmap for initmem, around rodata, and
[_brk_end, all_end).

Kernel Layout:

[ 0.000000] .text: [0x01000000-0x0200df88]
[ 0.000000] .rodata: [0x02200000-0x02a1dfff]
[ 0.000000] .data: [0x02c00000-0x02e510ff]
[ 0.000000] .init: [0x02e53000-0x03213fff]
[ 0.000000] .bss: [0x03222000-0x0437cfff]
[ 0.000000] .brk: [0x0437d000-0x043a2fff]

Actually used brk:
[ 0.270365] memblock_reserve: [0x0000000437d000-0x00000004383fff] flags 0x0 BRK

Before patch:
---[ High Kernel Mapping ]---
---[ High Kernel Mapping ]---
0xffffffff80000000-0xffffffff81000000 16M pmd
0xffffffff81000000-0xffffffff82000000 16M ro PSE GLB x pmd
0xffffffff82000000-0xffffffff82011000 68K ro GLB x pte
0xffffffff82011000-0xffffffff82200000 1980K RW GLB x pte
0xffffffff82200000-0xffffffff82a00000 8M ro PSE GLB NX pmd
0xffffffff82a00000-0xffffffff82a1e000 120K ro GLB NX pte
0xffffffff82a1e000-0xffffffff82c00000 1928K RW GLB NX pte
0xffffffff82c00000-0xffffffff82e00000 2M RW PSE GLB NX pmd
0xffffffff82e00000-0xffffffff83000000 2M RW GLB NX pte
0xffffffff83000000-0xffffffff83200000 2M RW PSE GLB NX pmd
0xffffffff83200000-0xffffffff83400000 2M RW GLB NX pte
0xffffffff83400000-0xffffffff84400000 16M RW PSE GLB NX pmd
0xffffffff84400000-0xffffffffa0000000 444M pmd

After patch:
---[ High Kernel Mapping ]---
0xffffffff80000000-0xffffffff81000000 16M pmd
0xffffffff81000000-0xffffffff82000000 16M ro PSE GLB x pmd
0xffffffff82000000-0xffffffff82012000 72K ro GLB x pte
0xffffffff82012000-0xffffffff82200000 1976K pte
0xffffffff82200000-0xffffffff82a00000 8M ro PSE GLB NX pmd
0xffffffff82a00000-0xffffffff82a1e000 120K ro GLB NX pte
0xffffffff82a1e000-0xffffffff82c00000 1928K pte
0xffffffff82c00000-0xffffffff82e00000 2M RW PSE GLB NX pmd
0xffffffff82e00000-0xffffffff82e53000 332K RW GLB NX pte
0xffffffff82e53000-0xffffffff83000000 1716K pte
0xffffffff83000000-0xffffffff83200000 2M pmd
0xffffffff83200000-0xffffffff83214000 80K pte
0xffffffff83214000-0xffffffff83400000 1968K RW GLB NX pte
0xffffffff83400000-0xffffffff84200000 14M RW PSE GLB NX pmd
0xffffffff84200000-0xffffffff84384000 1552K RW GLB NX pte
0xffffffff84384000-0xffffffff84400000 496K pte
0xffffffff84400000-0xffffffffa0000000 444M pmd

So remove some range before rodata with RW+x.

-v4: adapt it to all_end change.

Signed-off-by: Yinghai Lu <[email protected]>

---
arch/x86/mm/init_64.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 62 insertions(+)

Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -1101,6 +1101,61 @@ void __init mem_init(void)
}

#ifdef CONFIG_DEBUG_RODATA
+static void remove_highmap_2m(unsigned long addr)
+{
+ pgd_t *pgd = pgd_offset_k(addr);
+ pud_t *pud = (pud_t *)pgd_page_vaddr(*pgd) + pud_index(addr);
+ pmd_t *pmd = (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr);
+
+ set_pmd(pmd, __pmd(0));
+}
+
+static void remove_highmap_2m_partial(unsigned long addr, unsigned long end)
+{
+ int i;
+ pgd_t *pgd = pgd_offset_k(addr);
+ pud_t *pud = (pud_t *)pgd_page_vaddr(*pgd) + pud_index(addr);
+ pmd_t *pmd = (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr);
+ pte_t *pte = (pte_t *)pmd_page_vaddr(*pmd) + pte_index(addr);
+
+ for (i = pte_index(addr); i < pte_index(end - 1) + 1; i++, pte++)
+ set_pte(pte, __pte(0));
+}
+
+static void cleanup_highmap_late(unsigned long start, unsigned long end)
+{
+ unsigned long addr;
+ unsigned long start_2m_aligned = roundup(start, PMD_SIZE);
+ unsigned long end_2m_aligned = rounddown(end, PMD_SIZE);
+
+ start = PFN_ALIGN(start);
+ end &= PAGE_MASK;
+
+ if (start >= end)
+ return;
+
+ if (start < start_2m_aligned) {
+ unsigned long tmp = min(start_2m_aligned, end);
+
+ set_memory_4k(start, (tmp - start) >> PAGE_SHIFT);
+ remove_highmap_2m_partial(start, tmp);
+ }
+
+ for (addr = start_2m_aligned; addr < end_2m_aligned; addr += PMD_SIZE)
+ remove_highmap_2m(addr);
+
+ if (start <= end_2m_aligned && end_2m_aligned < end) {
+ set_memory_4k(end_2m_aligned,
+ (end - end_2m_aligned) >> PAGE_SHIFT);
+ remove_highmap_2m_partial(end_2m_aligned, end);
+ }
+
+ subtract_range(pfn_highmapped, NR_RANGE,
+ __pa_symbol(start) >> PAGE_SHIFT,
+ __pa_symbol(end) >> PAGE_SHIFT);
+ nr_pfn_highmapped = clean_sort_range(pfn_highmapped, NR_RANGE);
+}
+
const int rodata_test_data = 0xC3;
EXPORT_SYMBOL_GPL(rodata_test_data);

@@ -1149,6 +1204,7 @@ void mark_rodata_ro(void)
unsigned long end = (unsigned long) &__end_rodata_hpage_align;
unsigned long text_end = PFN_ALIGN(&__stop___ex_table);
unsigned long rodata_end = PFN_ALIGN(&__end_rodata);
+ unsigned long data_start = PFN_ALIGN(&_sdata);
unsigned long all_end;

printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
@@ -1172,6 +1228,12 @@ void mark_rodata_ro(void)
all_end = roundup(_brk_end, PMD_SIZE);
set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT);

+ cleanup_highmap_late(text_end, rodata_start);
+ cleanup_highmap_late(rodata_end, data_start);
+ cleanup_highmap_late(PFN_ALIGN(_brk_end), all_end);
+ cleanup_highmap_late((unsigned long)(&__init_begin),
+ (unsigned long)(&__init_end));
+
rodata_test();

#ifdef CONFIG_CPA_DEBUG

2014-11-19 01:49:03

by Yinghai Lu

[permalink] [raw]
Subject: Re: [PATCH 3/4] x86, 64bit: remove highmap for not needed ranges

On Tue, Nov 18, 2014 at 5:44 PM, Yinghai Lu <[email protected]> wrote:
> add cleanup_highmap_late to remove highmap for initmem, around rodata, and
> [_brk_end, all_end).

Sorry, title should be 3/3 instead of 3/4.

Thanks

Yinghai