mirror of
https://github.com/team-infusion-developers/android_kernel_samsung_msm8976.git
synced 2024-11-01 02:21:16 +00:00
6a11f75b6a
CONFIG_DEBUG_PAGEALLOC is now supported by x86, powerpc, sparc64, and s390. This patch implements it for the rest of the architectures by filling the pages with poison byte patterns after free_pages() and verifying the poison patterns before alloc_pages(). This generic one cannot detect invalid page accesses immediately but invalid read access may cause invalid dereference by poisoned memory and invalid write access can be detected after a long delay. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
129 lines
2.5 KiB
C
129 lines
2.5 KiB
C
#include <linux/kernel.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/page-debug-flags.h>
|
|
#include <linux/poison.h>
|
|
|
|
static inline void set_page_poison(struct page *page)
|
|
{
|
|
__set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
|
|
}
|
|
|
|
static inline void clear_page_poison(struct page *page)
|
|
{
|
|
__clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
|
|
}
|
|
|
|
static inline bool page_poison(struct page *page)
|
|
{
|
|
return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
|
|
}
|
|
|
|
static void poison_highpage(struct page *page)
|
|
{
|
|
/*
|
|
* Page poisoning for highmem pages is not implemented.
|
|
*
|
|
* This can be called from interrupt contexts.
|
|
* So we need to create a new kmap_atomic slot for this
|
|
* application and it will need interrupt protection.
|
|
*/
|
|
}
|
|
|
|
static void poison_page(struct page *page)
|
|
{
|
|
void *addr;
|
|
|
|
if (PageHighMem(page)) {
|
|
poison_highpage(page);
|
|
return;
|
|
}
|
|
set_page_poison(page);
|
|
addr = page_address(page);
|
|
memset(addr, PAGE_POISON, PAGE_SIZE);
|
|
}
|
|
|
|
static void poison_pages(struct page *page, int n)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < n; i++)
|
|
poison_page(page + i);
|
|
}
|
|
|
|
static bool single_bit_flip(unsigned char a, unsigned char b)
|
|
{
|
|
unsigned char error = a ^ b;
|
|
|
|
return error && !(error & (error - 1));
|
|
}
|
|
|
|
static void check_poison_mem(unsigned char *mem, size_t bytes)
|
|
{
|
|
unsigned char *start;
|
|
unsigned char *end;
|
|
|
|
for (start = mem; start < mem + bytes; start++) {
|
|
if (*start != PAGE_POISON)
|
|
break;
|
|
}
|
|
if (start == mem + bytes)
|
|
return;
|
|
|
|
for (end = mem + bytes - 1; end > start; end--) {
|
|
if (*end != PAGE_POISON)
|
|
break;
|
|
}
|
|
|
|
if (!printk_ratelimit())
|
|
return;
|
|
else if (start == end && single_bit_flip(*start, PAGE_POISON))
|
|
printk(KERN_ERR "pagealloc: single bit error\n");
|
|
else
|
|
printk(KERN_ERR "pagealloc: memory corruption\n");
|
|
|
|
print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
|
|
end - start + 1, 1);
|
|
dump_stack();
|
|
}
|
|
|
|
static void unpoison_highpage(struct page *page)
|
|
{
|
|
/*
|
|
* See comment in poison_highpage().
|
|
* Highmem pages should not be poisoned for now
|
|
*/
|
|
BUG_ON(page_poison(page));
|
|
}
|
|
|
|
static void unpoison_page(struct page *page)
|
|
{
|
|
if (PageHighMem(page)) {
|
|
unpoison_highpage(page);
|
|
return;
|
|
}
|
|
if (page_poison(page)) {
|
|
void *addr = page_address(page);
|
|
|
|
check_poison_mem(addr, PAGE_SIZE);
|
|
clear_page_poison(page);
|
|
}
|
|
}
|
|
|
|
static void unpoison_pages(struct page *page, int n)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < n; i++)
|
|
unpoison_page(page + i);
|
|
}
|
|
|
|
void kernel_map_pages(struct page *page, int numpages, int enable)
|
|
{
|
|
if (!debug_pagealloc_enabled)
|
|
return;
|
|
|
|
if (enable)
|
|
unpoison_pages(page, numpages);
|
|
else
|
|
poison_pages(page, numpages);
|
|
}
|