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Date:   Mon, 8 Mar 2021 12:26:11 +0100
From:   Marco Elver <elver@google.com>
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Alexander Potapenko <glider@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Peter Collingbourne <pcc@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/5] kasan: init memory in kasan_(un)poison for HW_TAGS
Message-ID: <YEYJ0+fmJykM0gjJ@elver.google.com>
References: <cover.1614989433.git.andreyknvl@google.com>
 <09ee2b0a0e9578885b2da1c963e9e94154d5d70a.1614989433.git.andreyknvl@google.com>
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On Sat, Mar 06, 2021 at 01:15AM +0100, Andrey Konovalov wrote:
> This change adds an argument to kasan_poison() and kasan_unpoison()
> that allows initializing memory along with setting the tags for HW_TAGS.
> 
> Combining setting allocation tags with memory initialization will
> improve HW_TAGS KASAN performance when init_on_alloc/free is enabled.
> 
> This change doesn't integrate memory initialization with KASAN,
> this is done is subsequent patches in this series.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

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

> ---
>  lib/test_kasan.c   |  4 ++--
>  mm/kasan/common.c  | 28 ++++++++++++++--------------
>  mm/kasan/generic.c | 12 ++++++------
>  mm/kasan/kasan.h   | 14 ++++++++------
>  mm/kasan/shadow.c  | 10 +++++-----
>  mm/kasan/sw_tags.c |  2 +-
>  6 files changed, 36 insertions(+), 34 deletions(-)
> 
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index e5647d147b35..d77c45edc7cd 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -1044,14 +1044,14 @@ static void match_all_mem_tag(struct kunit *test)
>  			continue;
>  
>  		/* Mark the first memory granule with the chosen memory tag. */
> -		kasan_poison(ptr, KASAN_GRANULE_SIZE, (u8)tag);
> +		kasan_poison(ptr, KASAN_GRANULE_SIZE, (u8)tag, false);
>  
>  		/* This access must cause a KASAN report. */
>  		KUNIT_EXPECT_KASAN_FAIL(test, *ptr = 0);
>  	}
>  
>  	/* Recover the memory tag and free. */
> -	kasan_poison(ptr, KASAN_GRANULE_SIZE, get_tag(ptr));
> +	kasan_poison(ptr, KASAN_GRANULE_SIZE, get_tag(ptr), false);
>  	kfree(ptr);
>  }
>  
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index b5e08d4cefec..316f7f8cd8e6 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -60,7 +60,7 @@ void kasan_disable_current(void)
>  
>  void __kasan_unpoison_range(const void *address, size_t size)
>  {
> -	kasan_unpoison(address, size);
> +	kasan_unpoison(address, size, false);
>  }
>  
>  #if CONFIG_KASAN_STACK
> @@ -69,7 +69,7 @@ void kasan_unpoison_task_stack(struct task_struct *task)
>  {
>  	void *base = task_stack_page(task);
>  
> -	kasan_unpoison(base, THREAD_SIZE);
> +	kasan_unpoison(base, THREAD_SIZE, false);
>  }
>  
>  /* Unpoison the stack for the current task beyond a watermark sp value. */
> @@ -82,7 +82,7 @@ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
>  	 */
>  	void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
>  
> -	kasan_unpoison(base, watermark - base);
> +	kasan_unpoison(base, watermark - base, false);
>  }
>  #endif /* CONFIG_KASAN_STACK */
>  
> @@ -108,14 +108,14 @@ void __kasan_alloc_pages(struct page *page, unsigned int order)
>  	tag = kasan_random_tag();
>  	for (i = 0; i < (1 << order); i++)
>  		page_kasan_tag_set(page + i, tag);
> -	kasan_unpoison(page_address(page), PAGE_SIZE << order);
> +	kasan_unpoison(page_address(page), PAGE_SIZE << order, false);
>  }
>  
>  void __kasan_free_pages(struct page *page, unsigned int order)
>  {
>  	if (likely(!PageHighMem(page)))
>  		kasan_poison(page_address(page), PAGE_SIZE << order,
> -			     KASAN_FREE_PAGE);
> +			     KASAN_FREE_PAGE, false);
>  }
>  
>  /*
> @@ -251,18 +251,18 @@ void __kasan_poison_slab(struct page *page)
>  	for (i = 0; i < compound_nr(page); i++)
>  		page_kasan_tag_reset(page + i);
>  	kasan_poison(page_address(page), page_size(page),
> -		     KASAN_KMALLOC_REDZONE);
> +		     KASAN_KMALLOC_REDZONE, false);
>  }
>  
>  void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
>  {
> -	kasan_unpoison(object, cache->object_size);
> +	kasan_unpoison(object, cache->object_size, false);
>  }
>  
>  void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
>  {
>  	kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
> -			KASAN_KMALLOC_REDZONE);
> +			KASAN_KMALLOC_REDZONE, false);
>  }
>  
>  /*
> @@ -351,7 +351,7 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache,
>  	}
>  
>  	kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
> -			KASAN_KMALLOC_FREE);
> +			KASAN_KMALLOC_FREE, false);
>  
>  	if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine))
>  		return false;
> @@ -407,7 +407,7 @@ void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
>  	if (unlikely(!PageSlab(page))) {
>  		if (____kasan_kfree_large(ptr, ip))
>  			return;
> -		kasan_poison(ptr, page_size(page), KASAN_FREE_PAGE);
> +		kasan_poison(ptr, page_size(page), KASAN_FREE_PAGE, false);
>  	} else {
>  		____kasan_slab_free(page->slab_cache, ptr, ip, false);
>  	}
> @@ -453,7 +453,7 @@ void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
>  	 * Unpoison the whole object.
>  	 * For kmalloc() allocations, kasan_kmalloc() will do precise poisoning.
>  	 */
> -	kasan_unpoison(tagged_object, cache->object_size);
> +	kasan_unpoison(tagged_object, cache->object_size, false);
>  
>  	/* Save alloc info (if possible) for non-kmalloc() allocations. */
>  	if (kasan_stack_collection_enabled())
> @@ -496,7 +496,7 @@ static inline void *____kasan_kmalloc(struct kmem_cache *cache,
>  	redzone_end = round_up((unsigned long)(object + cache->object_size),
>  				KASAN_GRANULE_SIZE);
>  	kasan_poison((void *)redzone_start, redzone_end - redzone_start,
> -			   KASAN_KMALLOC_REDZONE);
> +			   KASAN_KMALLOC_REDZONE, false);
>  
>  	/*
>  	 * Save alloc info (if possible) for kmalloc() allocations.
> @@ -546,7 +546,7 @@ void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
>  				KASAN_GRANULE_SIZE);
>  	redzone_end = (unsigned long)ptr + page_size(virt_to_page(ptr));
>  	kasan_poison((void *)redzone_start, redzone_end - redzone_start,
> -		     KASAN_PAGE_REDZONE);
> +		     KASAN_PAGE_REDZONE, false);
>  
>  	return (void *)ptr;
>  }
> @@ -563,7 +563,7 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag
>  	 * Part of it might already have been unpoisoned, but it's unknown
>  	 * how big that part is.
>  	 */
> -	kasan_unpoison(object, size);
> +	kasan_unpoison(object, size, false);
>  
>  	page = virt_to_head_page(object);
>  
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index 2e55e0f82f39..53cbf28859b5 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -208,11 +208,11 @@ static void register_global(struct kasan_global *global)
>  {
>  	size_t aligned_size = round_up(global->size, KASAN_GRANULE_SIZE);
>  
> -	kasan_unpoison(global->beg, global->size);
> +	kasan_unpoison(global->beg, global->size, false);
>  
>  	kasan_poison(global->beg + aligned_size,
>  		     global->size_with_redzone - aligned_size,
> -		     KASAN_GLOBAL_REDZONE);
> +		     KASAN_GLOBAL_REDZONE, false);
>  }
>  
>  void __asan_register_globals(struct kasan_global *globals, size_t size)
> @@ -292,11 +292,11 @@ void __asan_alloca_poison(unsigned long addr, size_t size)
>  	WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
>  
>  	kasan_unpoison((const void *)(addr + rounded_down_size),
> -			size - rounded_down_size);
> +			size - rounded_down_size, false);
>  	kasan_poison(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
> -		     KASAN_ALLOCA_LEFT);
> +		     KASAN_ALLOCA_LEFT, false);
>  	kasan_poison(right_redzone, padding_size + KASAN_ALLOCA_REDZONE_SIZE,
> -		     KASAN_ALLOCA_RIGHT);
> +		     KASAN_ALLOCA_RIGHT, false);
>  }
>  EXPORT_SYMBOL(__asan_alloca_poison);
>  
> @@ -306,7 +306,7 @@ void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
>  	if (unlikely(!stack_top || stack_top > stack_bottom))
>  		return;
>  
> -	kasan_unpoison(stack_top, stack_bottom - stack_top);
> +	kasan_unpoison(stack_top, stack_bottom - stack_top, false);
>  }
>  EXPORT_SYMBOL(__asan_allocas_unpoison);
>  
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 7fbb32234414..823a90d6a0cd 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -331,7 +331,7 @@ static inline u8 kasan_random_tag(void) { return 0; }
>  
>  #ifdef CONFIG_KASAN_HW_TAGS
>  
> -static inline void kasan_poison(const void *addr, size_t size, u8 value)
> +static inline void kasan_poison(const void *addr, size_t size, u8 value, bool init)
>  {
>  	addr = kasan_reset_tag(addr);
>  
> @@ -344,10 +344,10 @@ static inline void kasan_poison(const void *addr, size_t size, u8 value)
>  	if (WARN_ON(size & KASAN_GRANULE_MASK))
>  		return;
>  
> -	hw_set_mem_tag_range((void *)addr, size, value, false);
> +	hw_set_mem_tag_range((void *)addr, size, value, init);
>  }
>  
> -static inline void kasan_unpoison(const void *addr, size_t size)
> +static inline void kasan_unpoison(const void *addr, size_t size, bool init)
>  {
>  	u8 tag = get_tag(addr);
>  
> @@ -361,7 +361,7 @@ static inline void kasan_unpoison(const void *addr, size_t size)
>  		return;
>  	size = round_up(size, KASAN_GRANULE_SIZE);
>  
> -	hw_set_mem_tag_range((void *)addr, size, tag, false);
> +	hw_set_mem_tag_range((void *)addr, size, tag, init);
>  }
>  
>  static inline bool kasan_byte_accessible(const void *addr)
> @@ -380,22 +380,24 @@ static inline bool kasan_byte_accessible(const void *addr)
>   * @addr - range start address, must be aligned to KASAN_GRANULE_SIZE
>   * @size - range size, must be aligned to KASAN_GRANULE_SIZE
>   * @value - value that's written to metadata for the range
> + * @init - whether to initialize the memory range (only for hardware tag-based)
>   *
>   * The size gets aligned to KASAN_GRANULE_SIZE before marking the range.
>   */
> -void kasan_poison(const void *addr, size_t size, u8 value);
> +void kasan_poison(const void *addr, size_t size, u8 value, bool init);
>  
>  /**
>   * kasan_unpoison - mark the memory range as accessible
>   * @addr - range start address, must be aligned to KASAN_GRANULE_SIZE
>   * @size - range size, can be unaligned
> + * @init - whether to initialize the memory range (only for hardware tag-based)
>   *
>   * For the tag-based modes, the @size gets aligned to KASAN_GRANULE_SIZE before
>   * marking the range.
>   * For the generic mode, the last granule of the memory range gets partially
>   * unpoisoned based on the @size.
>   */
> -void kasan_unpoison(const void *addr, size_t size);
> +void kasan_unpoison(const void *addr, size_t size, bool init);
>  
>  bool kasan_byte_accessible(const void *addr);
>  
> diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
> index 63f43443f5d7..727ad4629173 100644
> --- a/mm/kasan/shadow.c
> +++ b/mm/kasan/shadow.c
> @@ -69,7 +69,7 @@ void *memcpy(void *dest, const void *src, size_t len)
>  	return __memcpy(dest, src, len);
>  }
>  
> -void kasan_poison(const void *addr, size_t size, u8 value)
> +void kasan_poison(const void *addr, size_t size, u8 value, bool init)
>  {
>  	void *shadow_start, *shadow_end;
>  
> @@ -106,7 +106,7 @@ void kasan_poison_last_granule(const void *addr, size_t size)
>  }
>  #endif
>  
> -void kasan_unpoison(const void *addr, size_t size)
> +void kasan_unpoison(const void *addr, size_t size, bool init)
>  {
>  	u8 tag = get_tag(addr);
>  
> @@ -129,7 +129,7 @@ void kasan_unpoison(const void *addr, size_t size)
>  		return;
>  
>  	/* Unpoison all granules that cover the object. */
> -	kasan_poison(addr, round_up(size, KASAN_GRANULE_SIZE), tag);
> +	kasan_poison(addr, round_up(size, KASAN_GRANULE_SIZE), tag, false);
>  
>  	/* Partially poison the last granule for the generic mode. */
>  	if (IS_ENABLED(CONFIG_KASAN_GENERIC))
> @@ -344,7 +344,7 @@ void kasan_poison_vmalloc(const void *start, unsigned long size)
>  		return;
>  
>  	size = round_up(size, KASAN_GRANULE_SIZE);
> -	kasan_poison(start, size, KASAN_VMALLOC_INVALID);
> +	kasan_poison(start, size, KASAN_VMALLOC_INVALID, false);
>  }
>  
>  void kasan_unpoison_vmalloc(const void *start, unsigned long size)
> @@ -352,7 +352,7 @@ void kasan_unpoison_vmalloc(const void *start, unsigned long size)
>  	if (!is_vmalloc_or_module_addr(start))
>  		return;
>  
> -	kasan_unpoison(start, size);
> +	kasan_unpoison(start, size, false);
>  }
>  
>  static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr,
> diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
> index 94c2d33be333..bd0c64d4e4d9 100644
> --- a/mm/kasan/sw_tags.c
> +++ b/mm/kasan/sw_tags.c
> @@ -159,7 +159,7 @@ EXPORT_SYMBOL(__hwasan_storeN_noabort);
>  
>  void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size)
>  {
> -	kasan_poison((void *)addr, size, tag);
> +	kasan_poison((void *)addr, size, tag, false);
>  }
>  EXPORT_SYMBOL(__hwasan_tag_memory);
>  
> -- 
> 2.30.1.766.gb4fecdf3b7-goog
>