kasan, mm: don't save alloc stacks twice

Patch series "kasan: optimizations and fixes for HW_TAGS", v4.

This patchset makes the HW_TAGS mode more efficient, mostly by reworking
poisoning approaches and simplifying/inlining some internal helpers.

With this change, the overhead of HW_TAGS annotations excluding setting
and checking memory tags is ~3%.  The performance impact caused by tags
will be unknown until we have hardware that supports MTE.

As a side-effect, this patchset speeds up generic KASAN by ~15%.

This patch (of 13):

Currently KASAN saves allocation stacks in both kasan_slab_alloc() and
kasan_kmalloc() annotations.  This patch changes KASAN to save allocation
stacks for slab objects from kmalloc caches in kasan_kmalloc() only, and
stacks for other slab objects in kasan_slab_alloc() only.

This change requires ____kasan_kmalloc() knowing whether the object
belongs to a kmalloc cache.  This is implemented by adding a flag field to
the kasan_info structure.  That flag is only set for kmalloc caches via a
new kasan_cache_create_kmalloc() annotation.

Link: https://lkml.kernel.org/r/cover.1612546384.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/7c673ebca8d00f40a7ad6f04ab9a2bddeeae2097.1612546384.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 7eaf2d9effb4..3fb31e8a353e 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -83,6 +83,7 @@ static inline void kasan_disable_current(void) {}
 struct kasan_cache {
 	int alloc_meta_offset;
 	int free_meta_offset;
+	bool is_kmalloc;
 };
 
 #ifdef CONFIG_KASAN_HW_TAGS
@@ -143,6 +144,13 @@ static __always_inline void kasan_cache_create(struct kmem_cache *cache,
 		__kasan_cache_create(cache, size, flags);
 }
 
+void __kasan_cache_create_kmalloc(struct kmem_cache *cache);
+static __always_inline void kasan_cache_create_kmalloc(struct kmem_cache *cache)
+{
+	if (kasan_enabled())
+		__kasan_cache_create_kmalloc(cache);
+}
+
 size_t __kasan_metadata_size(struct kmem_cache *cache);
 static __always_inline size_t kasan_metadata_size(struct kmem_cache *cache)
 {
@@ -278,6 +286,7 @@ static inline void kasan_free_pages(struct page *page, unsigned int order) {}
 static inline void kasan_cache_create(struct kmem_cache *cache,
 				      unsigned int *size,
 				      slab_flags_t *flags) {}
+static inline void kasan_cache_create_kmalloc(struct kmem_cache *cache) {}
 static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
 static inline void kasan_poison_slab(struct page *page) {}
 static inline void kasan_unpoison_object_data(struct kmem_cache *cache,