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authorAndrey Konovalov <andreyknvl@google.com>2022-03-25 02:11:26 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-25 03:06:47 +0100
commit53ae233c30a623ff44ff2f83854e92530c5d9fc2 (patch)
treea6fb500753f2d2a89a70c842ac91831582e75c0b /mm/page_alloc.c
parentkasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS (diff)
downloadlinux-53ae233c30a623ff44ff2f83854e92530c5d9fc2.tar.xz
linux-53ae233c30a623ff44ff2f83854e92530c5d9fc2.zip
kasan, page_alloc: allow skipping unpoisoning for HW_TAGS
Add a new GFP flag __GFP_SKIP_KASAN_UNPOISON that allows skipping KASAN poisoning for page_alloc allocations. The flag is only effective with HW_TAGS KASAN. This flag will be used by vmalloc code for page_alloc allocations backing vmalloc() mappings in a following patch. The reason to skip KASAN poisoning for these pages in page_alloc is because vmalloc code will be poisoning them instead. Also reword the comment for __GFP_SKIP_KASAN_POISON. Link: https://lkml.kernel.org/r/35c97d77a704f6ff971dd3bfe4be95855744108e.1643047180.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Acked-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c31
1 files changed, 22 insertions, 9 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 350bb27dc4bb..59a9408e1e7d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2343,6 +2343,26 @@ static inline bool check_new_pcp(struct page *page, unsigned int order)
}
#endif /* CONFIG_DEBUG_VM */
+static inline bool should_skip_kasan_unpoison(gfp_t flags, bool init_tags)
+{
+ /* Don't skip if a software KASAN mode is enabled. */
+ if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
+ IS_ENABLED(CONFIG_KASAN_SW_TAGS))
+ return false;
+
+ /* Skip, if hardware tag-based KASAN is not enabled. */
+ if (!kasan_hw_tags_enabled())
+ return true;
+
+ /*
+ * With hardware tag-based KASAN enabled, skip if either:
+ *
+ * 1. Memory tags have already been cleared via tag_clear_highpage().
+ * 2. Skipping has been requested via __GFP_SKIP_KASAN_UNPOISON.
+ */
+ return init_tags || (flags & __GFP_SKIP_KASAN_UNPOISON);
+}
+
inline void post_alloc_hook(struct page *page, unsigned int order,
gfp_t gfp_flags)
{
@@ -2382,15 +2402,8 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
/* Note that memory is already initialized by the loop above. */
init = false;
}
- /*
- * If either a software KASAN mode is enabled, or,
- * in the case of hardware tag-based KASAN,
- * if memory tags have not been cleared via tag_clear_highpage().
- */
- if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
- IS_ENABLED(CONFIG_KASAN_SW_TAGS) ||
- kasan_hw_tags_enabled() && !init_tags) {
- /* Mark shadow memory or set memory tags. */
+ if (!should_skip_kasan_unpoison(gfp_flags, init_tags)) {
+ /* Unpoison shadow memory or set memory tags. */
kasan_unpoison_pages(page, order, init);
/* Note that memory is already initialized by KASAN. */