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    Subject[PATCH RFC v2 15/21] kasan: check kasan_enabled in annotations
    From
    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.

    Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    Link: https://linux-review.googlesource.com/id/I2589451d3c96c97abbcbf714baabe6161c6f153e
    ---
    include/linux/kasan.h | 210 ++++++++++++++++++++++++++++++++----------
    include/linux/mm.h | 27 ++++--
    mm/kasan/common.c | 60 ++++++------
    3 files changed, 211 insertions(+), 86 deletions(-)

    diff --git a/include/linux/kasan.h b/include/linux/kasan.h
    index 2b9023224474..8654275aa62e 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/jump_label.h>
    #include <linux/types.h>

    struct kmem_cache;
    @@ -66,40 +67,154 @@ static inline void kasan_disable_current(void) {}

    #ifdef CONFIG_KASAN

    -void kasan_alloc_pages(struct page *page, unsigned int order);
    -void kasan_free_pages(struct page *page, unsigned int order);
    +struct kasan_cache {
    + int alloc_meta_offset;
    + int free_meta_offset;
    +};
    +
    +#ifdef CONFIG_KASAN_HW_TAGS
    +DECLARE_STATIC_KEY_FALSE(kasan_enabled);
    +#else
    +DECLARE_STATIC_KEY_TRUE(kasan_enabled);
    +#endif

    -void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
    - slab_flags_t *flags);
    +void __kasan_alloc_pages(struct page *page, unsigned int order);
    +static inline void kasan_alloc_pages(struct page *page, unsigned int order)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + __kasan_alloc_pages(page, order);
    +}

    -void kasan_unpoison_data(const void *address, size_t size);
    -void kasan_unpoison_slab(const void *ptr);
    +void __kasan_free_pages(struct page *page, unsigned int order);
    +static inline void kasan_free_pages(struct page *page, unsigned int order)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + __kasan_free_pages(page, order);
    +}

    -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_cache_create(struct kmem_cache *cache, unsigned int *size,
    + slab_flags_t *flags);
    +static inline void kasan_cache_create(struct kmem_cache *cache,
    + unsigned int *size, slab_flags_t *flags)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + __kasan_cache_create(cache, size, flags);
    +}

    -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);
    +size_t __kasan_metadata_size(struct kmem_cache *cache);
    +static inline size_t kasan_metadata_size(struct kmem_cache *cache)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + return __kasan_metadata_size(cache);
    + return 0;
    +}

    -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_unpoison_data(const void *addr, size_t size);
    +static inline void kasan_unpoison_data(const void *addr, size_t size)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + __kasan_unpoison_data(addr, size);
    +}

    -struct kasan_cache {
    - int alloc_meta_offset;
    - int free_meta_offset;
    -};
    +void __kasan_unpoison_slab(const void *ptr);
    +static inline void kasan_unpoison_slab(const void *ptr)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + __kasan_unpoison_slab(ptr);
    +}
    +
    +void __kasan_poison_slab(struct page *page);
    +static inline void kasan_poison_slab(struct page *page)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + return __kasan_poison_slab(page);
    +}
    +
    +void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
    +static inline void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + return __kasan_unpoison_object_data(cache, object);
    +}
    +
    +void __kasan_poison_object_data(struct kmem_cache *cache, void *object);
    +static inline void kasan_poison_object_data(struct kmem_cache *cache, void *object)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + __kasan_poison_object_data(cache, object);
    +}
    +
    +void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
    + const void *object);
    +static inline void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
    + const void *object)
    +{
    + if (static_branch_likely(&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 inline bool kasan_slab_free(struct kmem_cache *s, void *object, unsigned long ip)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + return __kasan_slab_free(s, object, ip);
    + return false;
    +}

    -size_t kasan_metadata_size(struct kmem_cache *cache);
    +void * __must_check __kasan_slab_alloc(struct kmem_cache *s,
    + void *object, gfp_t flags);
    +static inline void * __must_check kasan_slab_alloc(struct kmem_cache *s,
    + void *object, gfp_t flags)
    +{
    + if (static_branch_likely(&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 inline void * __must_check kasan_kmalloc(struct kmem_cache *s, const void *object,
    + size_t size, gfp_t flags)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + return __kasan_kmalloc(s, object, size, flags);
    + return (void *)object;
    +}
    +
    +void * __must_check __kasan_kmalloc_large(const void *ptr,
    + size_t size, gfp_t flags);
    +static inline void * __must_check kasan_kmalloc_large(const void *ptr,
    + size_t size, gfp_t flags)
    +{
    + if (static_branch_likely(&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 inline void * __must_check kasan_krealloc(const void *object,
    + size_t new_size, gfp_t flags)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + return __kasan_krealloc(object, new_size, flags);
    + return (void *)object;
    +}
    +
    +void __kasan_poison_kfree(void *ptr, unsigned long ip);
    +static inline void kasan_poison_kfree(void *ptr, unsigned long ip)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + __kasan_poison_kfree(ptr, ip);
    +}
    +
    +void __kasan_kfree_large(void *ptr, unsigned long ip);
    +static inline void kasan_kfree_large(void *ptr, unsigned long ip)
    +{
    + if (static_branch_likely(&kasan_enabled))
    + __kasan_kfree_large(ptr, ip);
    +}

    bool kasan_save_enable_multi_shot(void);
    void kasan_restore_multi_shot(bool enabled);
    @@ -108,14 +223,12 @@ void kasan_restore_multi_shot(bool enabled);

    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 void kasan_unpoison_data(const void *address, size_t size) { }
    -static inline void kasan_unpoison_slab(const void *ptr) { }
    -
    +static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
    +static inline void kasan_unpoison_data(const void *address, size_t size) {}
    +static inline void kasan_unpoison_slab(const void *ptr) {}
    static inline void kasan_poison_slab(struct page *page) {}
    static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
    void *object) {}
    @@ -126,36 +239,33 @@ 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_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)
    +static inline void *kasan_slab_alloc(struct kmem_cache *s, void *object,
    + gfp_t flags)
    {
    - return (void *)object;
    + return object;
    }
    -static inline void *kasan_krealloc(const void *object, size_t new_size,
    - gfp_t flags)
    +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_slab_alloc(struct kmem_cache *s, void *object,
    - gfp_t flags)
    +static inline void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
    {
    - return object;
    + return (void *)ptr;
    }
    -static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
    - unsigned long ip)
    +static inline void *kasan_krealloc(const void *object, size_t new_size,
    + gfp_t flags)
    {
    - return false;
    + return (void *)object;
    }
    -
    -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 a3cac68c737c..701e9d7666d6 100644
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -1412,22 +1412,36 @@ 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)
    +
    +#ifdef CONFIG_KASAN_HW_TAGS
    +DECLARE_STATIC_KEY_FALSE(kasan_enabled);
    +#else
    +DECLARE_STATIC_KEY_TRUE(kasan_enabled);
    +#endif
    +
    static inline u8 page_kasan_tag(const struct page *page)
    {
    - return (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
    + if (static_branch_likely(&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 (static_branch_likely(&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 (static_branch_likely(&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;
    @@ -1435,7 +1449,8 @@ 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 cc129ef62ab1..c5ec60e1a4d2 100644
    --- a/mm/kasan/common.c
    +++ b/mm/kasan/common.c
    @@ -81,7 +81,7 @@ 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;
    @@ -95,7 +95,7 @@ void kasan_alloc_pages(struct page *page, unsigned int order)
    kasan_unpoison_memory(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)))
    kasan_poison_memory(page_address(page),
    @@ -122,8 +122,8 @@ 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;
    @@ -165,7 +165,7 @@ 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 (static_branch_unlikely(&kasan_stack))
    return (cache->kasan_info.alloc_meta_offset ?
    @@ -188,17 +188,17 @@ struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
    return (void *)reset_tag(object) + cache->kasan_info.free_meta_offset;
    }

    -void kasan_unpoison_data(const void *address, size_t size)
    +void __kasan_unpoison_data(const void *addr, size_t size)
    {
    - kasan_unpoison_memory(address, size);
    + kasan_unpoison_memory(addr, size);
    }

    -void kasan_unpoison_slab(const void *ptr)
    +void __kasan_unpoison_slab(const void *ptr)
    {
    kasan_unpoison_memory(ptr, __ksize(ptr));
    }

    -void kasan_poison_slab(struct page *page)
    +void __kasan_poison_slab(struct page *page)
    {
    unsigned long i;

    @@ -208,12 +208,12 @@ 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)
    {
    kasan_unpoison_memory(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)
    {
    kasan_poison_memory(object,
    round_up(cache->object_size, KASAN_GRANULE_SIZE),
    @@ -266,7 +266,7 @@ 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;
    @@ -285,7 +285,7 @@ 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;
    @@ -329,9 +329,9 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
    return false;
    }

    -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)
    @@ -339,7 +339,7 @@ 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;
    @@ -371,20 +371,20 @@ 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;
    @@ -409,7 +409,7 @@ 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;

    @@ -419,13 +419,13 @@ 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;

    @@ -438,11 +438,11 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
    }
    kasan_poison_memory(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);
    --
    2.29.0.rc1.297.gfa9743e501-goog
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      Last update: 2020-10-22 15:20    [W:4.260 / U:0.028 seconds]
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