The patch titled
Subject: kasan, mm: don't save alloc stacks twice
has been added to the -mm tree. Its filename is
kasan-mm-dont-save-alloc-stacks-twice.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-mm-dont-save-alloc-stacks-twice.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-mm-dont-save-alloc-stacks-twice.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Link: https://lkml.kernel.org/r/7c673ebca8d00f40a7ad6f04ab9a2bddeeae2097.1612546384.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx>
Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kasan.h | 9 +++++++++
mm/kasan/common.c | 18 ++++++++++++++----
mm/slab_common.c | 1 +
3 files changed, 24 insertions(+), 4 deletions(-)
--- a/include/linux/kasan.h~kasan-mm-dont-save-alloc-stacks-twice
+++ a/include/linux/kasan.h
@@ -83,6 +83,7 @@ static inline void kasan_disable_current
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_
__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(stru
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,
--- a/mm/kasan/common.c~kasan-mm-dont-save-alloc-stacks-twice
+++ a/mm/kasan/common.c
@@ -210,6 +210,11 @@ void __kasan_cache_create(struct kmem_ca
*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
}
}
-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 km
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 km
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);
}
--- a/mm/slab_common.c~kasan-mm-dont-save-alloc-stacks-twice
+++ a/mm/slab_common.c
@@ -568,6 +568,7 @@ struct kmem_cache *__init create_kmalloc
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;
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-prefix-global-functions-with-kasan_.patch
kasan-clarify-hw_tags-impact-on-tbi.patch
kasan-clean-up-comments-in-tests.patch
kasan-add-macros-to-simplify-checking-test-constraints.patch
kasan-add-match-all-tag-tests.patch
kasan-arm64-allow-using-kunit-tests-with-hw_tags-mode.patch
kasan-rename-config_test_kasan_module.patch
kasan-add-compiler-barriers-to-kunit_expect_kasan_fail.patch
kasan-adapt-kmalloc_uaf2-test-to-hw_tags-mode.patch
kasan-fix-memory-corruption-in-kasan_bitops_tags-test.patch
kasan-move-_ret_ip_-to-inline-wrappers.patch
kasan-fix-bug-detection-via-ksize-for-hw_tags-mode.patch
kasan-add-proper-page-allocator-tests.patch
kasan-add-a-test-for-kmem_cache_alloc-free_bulk.patch
kasan-dont-run-tests-when-kasan-is-not-enabled.patch
kfence-kasan-make-kfence-compatible-with-kasan-fix-2.patch
kasan-mm-dont-save-alloc-stacks-twice.patch
kasan-mm-optimize-kmalloc-poisoning.patch
kasan-optimize-large-kmalloc-poisoning.patch
kasan-clean-up-setting-free-info-in-kasan_slab_free.patch
kasan-unify-large-kfree-checks.patch
kasan-rework-krealloc-tests.patch
kasan-mm-fail-krealloc-on-freed-objects.patch
kasan-mm-optimize-krealloc-poisoning.patch
kasan-ensure-poisoning-size-alignment.patch
arm64-kasan-simplify-and-inline-mte-functions.patch
kasan-inline-hw_tags-helper-functions.patch
arm64-kasan-export-mte-symbols-for-kasan-tests.patch
kasan-clarify-that-only-first-bug-is-reported-in-hw_tags.patch
