You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
133 lines
3.0 KiB
133 lines
3.0 KiB
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/kernel.h>
|
|
#include <linux/string.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/highmem.h>
|
|
#include <linux/page_ext.h>
|
|
#include <linux/poison.h>
|
|
#include <linux/ratelimit.h>
|
|
#include <linux/kasan.h>
|
|
|
|
static bool want_page_poisoning __read_mostly
|
|
= IS_ENABLED(CONFIG_PAGE_POISONING_ENABLE_DEFAULT);
|
|
|
|
static int early_page_poison_param(char *buf)
|
|
{
|
|
if (!buf)
|
|
return -EINVAL;
|
|
return strtobool(buf, &want_page_poisoning);
|
|
}
|
|
early_param("page_poison", early_page_poison_param);
|
|
|
|
bool page_poisoning_enabled(void)
|
|
{
|
|
/*
|
|
* Assumes that debug_pagealloc_enabled is set before
|
|
* free_all_bootmem.
|
|
* Page poisoning is debug page alloc for some arches. If
|
|
* either of those options are enabled, enable poisoning.
|
|
*/
|
|
return (want_page_poisoning ||
|
|
(!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
|
|
debug_pagealloc_enabled()));
|
|
}
|
|
|
|
static void poison_page(struct page *page)
|
|
{
|
|
void *addr = kmap_atomic(page);
|
|
|
|
/* KASAN still think the page is in-use, so skip it. */
|
|
kasan_disable_current();
|
|
memset(addr, PAGE_POISON, PAGE_SIZE);
|
|
kasan_enable_current();
|
|
kunmap_atomic(addr);
|
|
}
|
|
|
|
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(struct page *page,
|
|
unsigned char *mem, size_t bytes)
|
|
{
|
|
static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
|
|
unsigned char *start;
|
|
unsigned char *end;
|
|
|
|
if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY))
|
|
return;
|
|
|
|
start = memchr_inv(mem, PAGE_POISON, bytes);
|
|
if (!start)
|
|
return;
|
|
|
|
for (end = mem + bytes - 1; end > start; end--) {
|
|
if (*end != PAGE_POISON)
|
|
break;
|
|
}
|
|
|
|
if (!__ratelimit(&ratelimit))
|
|
return;
|
|
else if (start == end && single_bit_flip(*start, PAGE_POISON))
|
|
pr_err("pagealloc: single bit error on page with phys start 0x%lx\n",
|
|
(unsigned long)page_to_phys(page));
|
|
else
|
|
pr_err("pagealloc: memory corruption on page with phys start 0x%lx\n",
|
|
(unsigned long)page_to_phys(page));
|
|
|
|
print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
|
|
end - start + 1, 1);
|
|
BUG_ON(PANIC_CORRUPTION);
|
|
dump_stack();
|
|
}
|
|
|
|
static void unpoison_page(struct page *page)
|
|
{
|
|
void *addr;
|
|
|
|
addr = kmap_atomic(page);
|
|
/*
|
|
* Page poisoning when enabled poisons each and every page
|
|
* that is freed to buddy. Thus no extra check is done to
|
|
* see if a page was posioned.
|
|
*/
|
|
check_poison_mem(page, addr, PAGE_SIZE);
|
|
kunmap_atomic(addr);
|
|
}
|
|
|
|
static void unpoison_pages(struct page *page, int n)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < n; i++)
|
|
unpoison_page(page + i);
|
|
}
|
|
|
|
void kernel_poison_pages(struct page *page, int numpages, int enable)
|
|
{
|
|
if (!page_poisoning_enabled())
|
|
return;
|
|
|
|
if (enable)
|
|
unpoison_pages(page, numpages);
|
|
else
|
|
poison_pages(page, numpages);
|
|
}
|
|
|
|
#ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC
|
|
void __kernel_map_pages(struct page *page, int numpages, int enable)
|
|
{
|
|
/* This function does nothing, all work is done via poison pages */
|
|
}
|
|
#endif
|
|
|