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authorAndrey Konovalov <andreyknvl@google.com>2021-02-25 17:19:55 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-26 09:41:02 -0800
commit928501344fc645f80390afc12708c81b3595745d (patch)
tree98e66961054a59acab4663ee4249eaa33f7c1535 /mm
parentd3a61f745e0d089a2484740283a434deb6dd4eb5 (diff)
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/kasan/common.c18
-rw-r--r--mm/slab_common.c1
2 files changed, 15 insertions, 4 deletions
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index af1768c4fee5..d8d83ca56fe2 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -210,6 +210,11 @@ void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
*size = optimal_size;
}
+void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
+{
+ cache->kasan_info.is_kmalloc = true;
+}
+
size_t __kasan_metadata_size(struct kmem_cache *cache)
{
if (!kasan_stack_collection_enabled())
@@ -394,17 +399,22 @@ void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
}
}
-static void set_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
+static void set_alloc_info(struct kmem_cache *cache, void *object,
+ gfp_t flags, bool is_kmalloc)
{
struct kasan_alloc_meta *alloc_meta;
+ /* Don't save alloc info for kmalloc caches in kasan_slab_alloc(). */
+ if (cache->kasan_info.is_kmalloc && !is_kmalloc)
+ return;
+
alloc_meta = kasan_get_alloc_meta(cache, object);
if (alloc_meta)
kasan_set_track(&alloc_meta->alloc_track, flags);
}
static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
- size_t size, gfp_t flags, bool keep_tag)
+ size_t size, gfp_t flags, bool is_kmalloc)
{
unsigned long redzone_start;
unsigned long redzone_end;
@@ -423,7 +433,7 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
KASAN_GRANULE_SIZE);
redzone_end = round_up((unsigned long)object + cache->object_size,
KASAN_GRANULE_SIZE);
- tag = assign_tag(cache, object, false, keep_tag);
+ tag = assign_tag(cache, object, false, is_kmalloc);
/* Tag is ignored in set_tag without CONFIG_KASAN_SW/HW_TAGS */
kasan_unpoison(set_tag(object, tag), size);
@@ -431,7 +441,7 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
KASAN_KMALLOC_REDZONE);
if (kasan_stack_collection_enabled())
- set_alloc_info(cache, (void *)object, flags);
+ set_alloc_info(cache, (void *)object, flags, is_kmalloc);
return set_tag(object, tag);
}
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 284954ef1da5..897c3a446b04 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -643,6 +643,7 @@ struct kmem_cache *__init create_kmalloc_cache(const char *name,
panic("Out of memory when creating slab %s\n", name);
create_boot_cache(s, name, size, flags, useroffset, usersize);
+ kasan_cache_create_kmalloc(s);
list_add(&s->list, &slab_caches);
s->refcount = 1;
return s;