// SPDX-License-Identifier: GPL-2.0 #include <linux/kernel.h> #include <linux/string.h> #include <linux/mm.h> #include <linux/mmdebug.h> #include <linux/highmem.h> #include <linux/page_ext.h> #include <linux/poison.h> #include <linux/ratelimit.h> #include <linux/kasan.h> bool _page_poisoning_enabled_early; EXPORT_SYMBOL(_page_poisoning_enabled_early); DEFINE_STATIC_KEY_FALSE(_page_poisoning_enabled); EXPORT_SYMBOL(_page_poisoning_enabled); static int __init early_page_poison_param(char *buf) { return kstrtobool(buf, &_page_poisoning_enabled_early); } early_param("page_poison", early_page_poison_param); 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(kasan_reset_tag(addr), PAGE_POISON, PAGE_SIZE); kasan_enable_current(); kunmap_atomic(addr); } void __kernel_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; 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\n"); else pr_err("pagealloc: memory corruption\n"); print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, end - start + 1, 1); dump_stack(); dump_page(page, "pagealloc: corrupted page details"); } static void unpoison_page(struct page *page) { void *addr; addr = kmap_atomic(page); kasan_disable_current(); /* * 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 poisoned. */ check_poison_mem(page, kasan_reset_tag(addr), PAGE_SIZE); kasan_enable_current(); kunmap_atomic(addr); } void __kernel_unpoison_pages(struct page *page, int n) { int i; for (i = 0; i < n; i++) unpoison_page(page + i); } #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