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    SubjectRe: [PATCH mm v3 12/19] kasan, mm: check kasan_enabled in annotations
    On Fri, Nov 13, 2020 at 11:20PM +0100, Andrey Konovalov wrote:
    > Declare the kasan_enabled static key in include/linux/kasan.h and in
    > include/linux/mm.h and check it in all kasan annotations. This allows to
    > avoid any slowdown caused by function calls when kasan_enabled is
    > disabled.
    >
    > Co-developed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
    > Signed-off-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
    > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    > Link: https://linux-review.googlesource.com/id/I2589451d3c96c97abbcbf714baabe6161c6f153e

    Reviewed-by: Marco Elver <elver@google.com>

    > ---
    > include/linux/kasan.h | 213 ++++++++++++++++++++++++++++++++----------
    > include/linux/mm.h | 22 +++--
    > mm/kasan/common.c | 56 +++++------
    > 3 files changed, 210 insertions(+), 81 deletions(-)
    >
    > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
    > index 872bf145ddde..6bd95243a583 100644
    > --- a/include/linux/kasan.h
    > +++ b/include/linux/kasan.h
    > @@ -2,6 +2,7 @@
    > #ifndef _LINUX_KASAN_H
    > #define _LINUX_KASAN_H
    >
    > +#include <linux/static_key.h>
    > #include <linux/types.h>
    >
    > struct kmem_cache;
    > @@ -74,54 +75,176 @@ static inline void kasan_disable_current(void) {}
    >
    > #ifdef CONFIG_KASAN
    >
    > -void kasan_unpoison_range(const void *address, size_t size);
    > +struct kasan_cache {
    > + int alloc_meta_offset;
    > + int free_meta_offset;
    > +};
    >
    > -void kasan_alloc_pages(struct page *page, unsigned int order);
    > -void kasan_free_pages(struct page *page, unsigned int order);
    > +#ifdef CONFIG_KASAN_HW_TAGS
    > +DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
    > +static __always_inline bool kasan_enabled(void)
    > +{
    > + return static_branch_likely(&kasan_flag_enabled);
    > +}
    > +#else
    > +static inline bool kasan_enabled(void)
    > +{
    > + return true;
    > +}
    > +#endif
    >
    > -void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
    > - slab_flags_t *flags);
    > +void __kasan_unpoison_range(const void *addr, size_t size);
    > +static __always_inline void kasan_unpoison_range(const void *addr, size_t size)
    > +{
    > + if (kasan_enabled())
    > + __kasan_unpoison_range(addr, size);
    > +}
    >
    > -void kasan_poison_slab(struct page *page);
    > -void kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
    > -void kasan_poison_object_data(struct kmem_cache *cache, void *object);
    > -void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
    > - const void *object);
    > +void __kasan_alloc_pages(struct page *page, unsigned int order);
    > +static __always_inline void kasan_alloc_pages(struct page *page,
    > + unsigned int order)
    > +{
    > + if (kasan_enabled())
    > + __kasan_alloc_pages(page, order);
    > +}
    >
    > -void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
    > - gfp_t flags);
    > -void kasan_kfree_large(void *ptr, unsigned long ip);
    > -void kasan_poison_kfree(void *ptr, unsigned long ip);
    > -void * __must_check kasan_kmalloc(struct kmem_cache *s, const void *object,
    > - size_t size, gfp_t flags);
    > -void * __must_check kasan_krealloc(const void *object, size_t new_size,
    > - gfp_t flags);
    > +void __kasan_free_pages(struct page *page, unsigned int order);
    > +static __always_inline void kasan_free_pages(struct page *page,
    > + unsigned int order)
    > +{
    > + if (kasan_enabled())
    > + __kasan_free_pages(page, order);
    > +}
    >
    > -void * __must_check kasan_slab_alloc(struct kmem_cache *s, void *object,
    > - gfp_t flags);
    > -bool kasan_slab_free(struct kmem_cache *s, void *object, unsigned long ip);
    > +void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
    > + slab_flags_t *flags);
    > +static __always_inline void kasan_cache_create(struct kmem_cache *cache,
    > + unsigned int *size, slab_flags_t *flags)
    > +{
    > + if (kasan_enabled())
    > + __kasan_cache_create(cache, size, flags);
    > +}
    >
    > -struct kasan_cache {
    > - int alloc_meta_offset;
    > - int free_meta_offset;
    > -};
    > +size_t __kasan_metadata_size(struct kmem_cache *cache);
    > +static __always_inline size_t kasan_metadata_size(struct kmem_cache *cache)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_metadata_size(cache);
    > + return 0;
    > +}
    > +
    > +void __kasan_poison_slab(struct page *page);
    > +static __always_inline void kasan_poison_slab(struct page *page)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_poison_slab(page);
    > +}
    > +
    > +void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
    > +static __always_inline void kasan_unpoison_object_data(struct kmem_cache *cache,
    > + void *object)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_unpoison_object_data(cache, object);
    > +}
    > +
    > +void __kasan_poison_object_data(struct kmem_cache *cache, void *object);
    > +static __always_inline void kasan_poison_object_data(struct kmem_cache *cache,
    > + void *object)
    > +{
    > + if (kasan_enabled())
    > + __kasan_poison_object_data(cache, object);
    > +}
    > +
    > +void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
    > + const void *object);
    > +static __always_inline void * __must_check kasan_init_slab_obj(
    > + struct kmem_cache *cache, const void *object)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_init_slab_obj(cache, object);
    > + return (void *)object;
    > +}
    > +
    > +bool __kasan_slab_free(struct kmem_cache *s, void *object, unsigned long ip);
    > +static __always_inline bool kasan_slab_free(struct kmem_cache *s, void *object,
    > + unsigned long ip)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_slab_free(s, object, ip);
    > + return false;
    > +}
    > +
    > +void * __must_check __kasan_slab_alloc(struct kmem_cache *s,
    > + void *object, gfp_t flags);
    > +static __always_inline void * __must_check kasan_slab_alloc(
    > + struct kmem_cache *s, void *object, gfp_t flags)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_slab_alloc(s, object, flags);
    > + return object;
    > +}
    > +
    > +void * __must_check __kasan_kmalloc(struct kmem_cache *s, const void *object,
    > + size_t size, gfp_t flags);
    > +static __always_inline void * __must_check kasan_kmalloc(struct kmem_cache *s,
    > + const void *object, size_t size, gfp_t flags)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_kmalloc(s, object, size, flags);
    > + return (void *)object;
    > +}
    >
    > -size_t kasan_metadata_size(struct kmem_cache *cache);
    > +void * __must_check __kasan_kmalloc_large(const void *ptr,
    > + size_t size, gfp_t flags);
    > +static __always_inline void * __must_check kasan_kmalloc_large(const void *ptr,
    > + size_t size, gfp_t flags)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_kmalloc_large(ptr, size, flags);
    > + return (void *)ptr;
    > +}
    > +
    > +void * __must_check __kasan_krealloc(const void *object,
    > + size_t new_size, gfp_t flags);
    > +static __always_inline void * __must_check kasan_krealloc(const void *object,
    > + size_t new_size, gfp_t flags)
    > +{
    > + if (kasan_enabled())
    > + return __kasan_krealloc(object, new_size, flags);
    > + return (void *)object;
    > +}
    > +
    > +void __kasan_poison_kfree(void *ptr, unsigned long ip);
    > +static __always_inline void kasan_poison_kfree(void *ptr, unsigned long ip)
    > +{
    > + if (kasan_enabled())
    > + __kasan_poison_kfree(ptr, ip);
    > +}
    > +
    > +void __kasan_kfree_large(void *ptr, unsigned long ip);
    > +static __always_inline void kasan_kfree_large(void *ptr, unsigned long ip)
    > +{
    > + if (kasan_enabled())
    > + __kasan_kfree_large(ptr, ip);
    > +}
    >
    > bool kasan_save_enable_multi_shot(void);
    > void kasan_restore_multi_shot(bool enabled);
    >
    > #else /* CONFIG_KASAN */
    >
    > +static inline bool kasan_enabled(void)
    > +{
    > + return false;
    > +}
    > static inline void kasan_unpoison_range(const void *address, size_t size) {}
    > -
    > static inline void kasan_alloc_pages(struct page *page, unsigned int order) {}
    > 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 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,
    > void *object) {}
    > @@ -132,36 +255,32 @@ static inline void *kasan_init_slab_obj(struct kmem_cache *cache,
    > {
    > return (void *)object;
    > }
    > -
    > -static inline void *kasan_kmalloc_large(void *ptr, size_t size, gfp_t flags)
    > +static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
    > + unsigned long ip)
    > {
    > - return ptr;
    > + return false;
    > +}
    > +static inline void *kasan_slab_alloc(struct kmem_cache *s, void *object,
    > + gfp_t flags)
    > +{
    > + return object;
    > }
    > -static inline void kasan_kfree_large(void *ptr, unsigned long ip) {}
    > -static inline void kasan_poison_kfree(void *ptr, unsigned long ip) {}
    > static inline void *kasan_kmalloc(struct kmem_cache *s, const void *object,
    > size_t size, gfp_t flags)
    > {
    > return (void *)object;
    > }
    > +static inline void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
    > +{
    > + return (void *)ptr;
    > +}
    > static inline void *kasan_krealloc(const void *object, size_t new_size,
    > gfp_t flags)
    > {
    > return (void *)object;
    > }
    > -
    > -static inline void *kasan_slab_alloc(struct kmem_cache *s, void *object,
    > - gfp_t flags)
    > -{
    > - return object;
    > -}
    > -static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
    > - unsigned long ip)
    > -{
    > - return false;
    > -}
    > -
    > -static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
    > +static inline void kasan_poison_kfree(void *ptr, unsigned long ip) {}
    > +static inline void kasan_kfree_large(void *ptr, unsigned long ip) {}
    >
    > #endif /* CONFIG_KASAN */
    >
    > diff --git a/include/linux/mm.h b/include/linux/mm.h
    > index 947f4f1a6536..24f47e140a4c 100644
    > --- a/include/linux/mm.h
    > +++ b/include/linux/mm.h
    > @@ -31,6 +31,7 @@
    > #include <linux/sizes.h>
    > #include <linux/sched.h>
    > #include <linux/pgtable.h>
    > +#include <linux/kasan.h>
    >
    > struct mempolicy;
    > struct anon_vma;
    > @@ -1415,22 +1416,30 @@ static inline bool cpupid_match_pid(struct task_struct *task, int cpupid)
    > #endif /* CONFIG_NUMA_BALANCING */
    >
    > #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
    > +
    > static inline u8 page_kasan_tag(const struct page *page)
    > {
    > - return (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
    > + if (kasan_enabled())
    > + return (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
    > + return 0xff;
    > }
    >
    > static inline void page_kasan_tag_set(struct page *page, u8 tag)
    > {
    > - page->flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
    > - page->flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
    > + if (kasan_enabled()) {
    > + page->flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
    > + page->flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
    > + }
    > }
    >
    > static inline void page_kasan_tag_reset(struct page *page)
    > {
    > - page_kasan_tag_set(page, 0xff);
    > + if (kasan_enabled())
    > + page_kasan_tag_set(page, 0xff);
    > }
    > -#else
    > +
    > +#else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
    > +
    > static inline u8 page_kasan_tag(const struct page *page)
    > {
    > return 0xff;
    > @@ -1438,7 +1447,8 @@ static inline u8 page_kasan_tag(const struct page *page)
    >
    > static inline void page_kasan_tag_set(struct page *page, u8 tag) { }
    > static inline void page_kasan_tag_reset(struct page *page) { }
    > -#endif
    > +
    > +#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
    >
    > static inline struct zone *page_zone(const struct page *page)
    > {
    > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
    > index a11e3e75eb08..17918bd20ed9 100644
    > --- a/mm/kasan/common.c
    > +++ b/mm/kasan/common.c
    > @@ -59,7 +59,7 @@ void kasan_disable_current(void)
    > }
    > #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
    >
    > -void kasan_unpoison_range(const void *address, size_t size)
    > +void __kasan_unpoison_range(const void *address, size_t size)
    > {
    > unpoison_range(address, size);
    > }
    > @@ -87,7 +87,7 @@ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
    > }
    > #endif /* CONFIG_KASAN_STACK */
    >
    > -void kasan_alloc_pages(struct page *page, unsigned int order)
    > +void __kasan_alloc_pages(struct page *page, unsigned int order)
    > {
    > u8 tag;
    > unsigned long i;
    > @@ -101,7 +101,7 @@ void kasan_alloc_pages(struct page *page, unsigned int order)
    > unpoison_range(page_address(page), PAGE_SIZE << order);
    > }
    >
    > -void kasan_free_pages(struct page *page, unsigned int order)
    > +void __kasan_free_pages(struct page *page, unsigned int order)
    > {
    > if (likely(!PageHighMem(page)))
    > poison_range(page_address(page),
    > @@ -128,8 +128,8 @@ static inline unsigned int optimal_redzone(unsigned int object_size)
    > object_size <= (1 << 16) - 1024 ? 1024 : 2048;
    > }
    >
    > -void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
    > - slab_flags_t *flags)
    > +void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
    > + slab_flags_t *flags)
    > {
    > unsigned int orig_size = *size;
    > unsigned int redzone_size;
    > @@ -174,7 +174,7 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
    > *flags |= SLAB_KASAN;
    > }
    >
    > -size_t kasan_metadata_size(struct kmem_cache *cache)
    > +size_t __kasan_metadata_size(struct kmem_cache *cache)
    > {
    > if (!kasan_stack_collection_enabled())
    > return 0;
    > @@ -197,7 +197,7 @@ struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
    > return kasan_reset_tag(object) + cache->kasan_info.free_meta_offset;
    > }
    >
    > -void kasan_poison_slab(struct page *page)
    > +void __kasan_poison_slab(struct page *page)
    > {
    > unsigned long i;
    >
    > @@ -207,12 +207,12 @@ void kasan_poison_slab(struct page *page)
    > KASAN_KMALLOC_REDZONE);
    > }
    >
    > -void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
    > +void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
    > {
    > unpoison_range(object, cache->object_size);
    > }
    >
    > -void kasan_poison_object_data(struct kmem_cache *cache, void *object)
    > +void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
    > {
    > poison_range(object,
    > round_up(cache->object_size, KASAN_GRANULE_SIZE),
    > @@ -265,7 +265,7 @@ static u8 assign_tag(struct kmem_cache *cache, const void *object,
    > #endif
    > }
    >
    > -void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
    > +void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
    > const void *object)
    > {
    > struct kasan_alloc_meta *alloc_meta;
    > @@ -284,7 +284,7 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
    > return (void *)object;
    > }
    >
    > -static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
    > +static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
    > unsigned long ip, bool quarantine)
    > {
    > u8 tag;
    > @@ -330,9 +330,9 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
    > return IS_ENABLED(CONFIG_KASAN_GENERIC);
    > }
    >
    > -bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
    > +bool __kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
    > {
    > - return __kasan_slab_free(cache, object, ip, true);
    > + return ____kasan_slab_free(cache, object, ip, true);
    > }
    >
    > static void set_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
    > @@ -340,7 +340,7 @@ static void set_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
    > kasan_set_track(&kasan_get_alloc_meta(cache, object)->alloc_track, flags);
    > }
    >
    > -static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
    > +static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
    > size_t size, gfp_t flags, bool keep_tag)
    > {
    > unsigned long redzone_start;
    > @@ -375,20 +375,20 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
    > return set_tag(object, tag);
    > }
    >
    > -void * __must_check kasan_slab_alloc(struct kmem_cache *cache, void *object,
    > - gfp_t flags)
    > +void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
    > + void *object, gfp_t flags)
    > {
    > - return __kasan_kmalloc(cache, object, cache->object_size, flags, false);
    > + return ____kasan_kmalloc(cache, object, cache->object_size, flags, false);
    > }
    >
    > -void * __must_check kasan_kmalloc(struct kmem_cache *cache, const void *object,
    > - size_t size, gfp_t flags)
    > +void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object,
    > + size_t size, gfp_t flags)
    > {
    > - return __kasan_kmalloc(cache, object, size, flags, true);
    > + return ____kasan_kmalloc(cache, object, size, flags, true);
    > }
    > -EXPORT_SYMBOL(kasan_kmalloc);
    > +EXPORT_SYMBOL(__kasan_kmalloc);
    >
    > -void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
    > +void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
    > gfp_t flags)
    > {
    > struct page *page;
    > @@ -413,7 +413,7 @@ void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
    > return (void *)ptr;
    > }
    >
    > -void * __must_check kasan_krealloc(const void *object, size_t size, gfp_t flags)
    > +void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
    > {
    > struct page *page;
    >
    > @@ -423,13 +423,13 @@ void * __must_check kasan_krealloc(const void *object, size_t size, gfp_t flags)
    > page = virt_to_head_page(object);
    >
    > if (unlikely(!PageSlab(page)))
    > - return kasan_kmalloc_large(object, size, flags);
    > + return __kasan_kmalloc_large(object, size, flags);
    > else
    > - return __kasan_kmalloc(page->slab_cache, object, size,
    > + return ____kasan_kmalloc(page->slab_cache, object, size,
    > flags, true);
    > }
    >
    > -void kasan_poison_kfree(void *ptr, unsigned long ip)
    > +void __kasan_poison_kfree(void *ptr, unsigned long ip)
    > {
    > struct page *page;
    >
    > @@ -442,11 +442,11 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
    > }
    > poison_range(ptr, page_size(page), KASAN_FREE_PAGE);
    > } else {
    > - __kasan_slab_free(page->slab_cache, ptr, ip, false);
    > + ____kasan_slab_free(page->slab_cache, ptr, ip, false);
    > }
    > }
    >
    > -void kasan_kfree_large(void *ptr, unsigned long ip)
    > +void __kasan_kfree_large(void *ptr, unsigned long ip)
    > {
    > if (ptr != page_address(virt_to_head_page(ptr)))
    > kasan_report_invalid_free(ptr, ip);
    > --
    > 2.29.2.299.gdc1121823c-goog
    >

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