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Date:   Wed, 11 Nov 2020 17:42:03 +0100
From:   Marco Elver <elver@google.com>
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 06/20] kasan: remove __kasan_unpoison_stack
Message-ID: <20201111164203.GH517454@elver.google.com>
References: <cover.1605046662.git.andreyknvl@google.com>
 <462c375f39ba8c4c105b3a9bf3b5db17f3720159.1605046662.git.andreyknvl@google.com>
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On Tue, Nov 10, 2020 at 11:20PM +0100, Andrey Konovalov wrote:
> There's no need for __kasan_unpoison_stack() helper, as it's only
> currently used in a single place. Removing it also removes unneeded
> arithmetic.
> 
> No functional changes.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> Link: https://linux-review.googlesource.com/id/Ie5ba549d445292fe629b4a96735e4034957bcc50
> ---
>  mm/kasan/common.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)

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

Thanks for spotting this simplification.

> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index a3e67d49b893..9008fc6b0810 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -59,18 +59,12 @@ void kasan_disable_current(void)
>  #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
>  
>  #if CONFIG_KASAN_STACK
> -static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
> -{
> -	void *base = task_stack_page(task);
> -	size_t size = sp - base;
> -
> -	kasan_unpoison_memory(base, size);
> -}
> -
>  /* Unpoison the entire stack for a task. */
>  void kasan_unpoison_task_stack(struct task_struct *task)
>  {
> -	__kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE);
> +	void *base = task_stack_page(task);
> +
> +	kasan_unpoison_memory(base, THREAD_SIZE);
>  }
>  
>  /* Unpoison the stack for the current task beyond a watermark sp value. */
> -- 
> 2.29.2.222.g5d2a92d10f8-goog
>