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From: Catalin Marinas <catalin.marinas@arm.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will.deacon@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 v2 1/5] arm64: kasan: allow to init memory when setting tags
Date: Mon, 8 Mar 2021 16:58:47 +0000	[thread overview]
Message-ID: <20210308165847.GF15644@arm.com> (raw)
In-Reply-To: <755161094eac5b0fc15273d609c78a459d4d07b9.1615218180.git.andreyknvl@google.com>

On Mon, Mar 08, 2021 at 04:55:14PM +0100, Andrey Konovalov wrote:
> @@ -68,10 +69,16 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
>  		 * 'asm volatile' is required to prevent the compiler to move
>  		 * the statement outside of the loop.
>  		 */
> -		asm volatile(__MTE_PREAMBLE "stg %0, [%0]"
> -			     :
> -			     : "r" (curr)
> -			     : "memory");
> +		if (init)
> +			asm volatile(__MTE_PREAMBLE "stzg %0, [%0]"
> +				     :
> +				     : "r" (curr)
> +				     : "memory");
> +		else
> +			asm volatile(__MTE_PREAMBLE "stg %0, [%0]"
> +				     :
> +				     : "r" (curr)
> +				     : "memory");
>  
>  		curr += MTE_GRANULE_SIZE;
>  	} while (curr != end);

Is 'init' always a built-in constant here? If not, checking it once
outside the loop may be better (or check the code generation, maybe the
compiler is smart enough).

-- 
Catalin

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will.deacon@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 v2 1/5] arm64: kasan: allow to init memory when setting tags
Date: Mon, 8 Mar 2021 16:58:47 +0000	[thread overview]
Message-ID: <20210308165847.GF15644@arm.com> (raw)
In-Reply-To: <755161094eac5b0fc15273d609c78a459d4d07b9.1615218180.git.andreyknvl@google.com>

On Mon, Mar 08, 2021 at 04:55:14PM +0100, Andrey Konovalov wrote:
> @@ -68,10 +69,16 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
>  		 * 'asm volatile' is required to prevent the compiler to move
>  		 * the statement outside of the loop.
>  		 */
> -		asm volatile(__MTE_PREAMBLE "stg %0, [%0]"
> -			     :
> -			     : "r" (curr)
> -			     : "memory");
> +		if (init)
> +			asm volatile(__MTE_PREAMBLE "stzg %0, [%0]"
> +				     :
> +				     : "r" (curr)
> +				     : "memory");
> +		else
> +			asm volatile(__MTE_PREAMBLE "stg %0, [%0]"
> +				     :
> +				     : "r" (curr)
> +				     : "memory");
>  
>  		curr += MTE_GRANULE_SIZE;
>  	} while (curr != end);

Is 'init' always a built-in constant here? If not, checking it once
outside the loop may be better (or check the code generation, maybe the
compiler is smart enough).

-- 
Catalin


  reply	other threads:[~2021-03-08 17:00 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-08 15:55 [PATCH v2 0/5] kasan: integrate with init_on_alloc/free Andrey Konovalov
2021-03-08 15:55 ` Andrey Konovalov
2021-03-08 15:55 ` [PATCH v2 1/5] arm64: kasan: allow to init memory when setting tags Andrey Konovalov
2021-03-08 15:55   ` Andrey Konovalov
2021-03-08 16:58   ` Catalin Marinas [this message]
2021-03-08 16:58     ` Catalin Marinas
2021-03-09 13:09     ` Andrey Konovalov
2021-03-09 13:09       ` Andrey Konovalov
2021-03-08 15:55 ` [PATCH v2 2/5] kasan: init memory in kasan_(un)poison for HW_TAGS Andrey Konovalov
2021-03-08 15:55   ` Andrey Konovalov
2021-03-08 15:55 ` [PATCH v2 3/5] kasan, mm: integrate page_alloc init with HW_TAGS Andrey Konovalov
2021-03-08 15:55   ` Andrey Konovalov
2021-03-08 16:07   ` Marco Elver
2021-03-08 16:07     ` Marco Elver
2021-03-08 15:55 ` [PATCH v2 4/5] kasan, mm: integrate slab init_on_alloc " Andrey Konovalov
2021-03-08 15:55   ` Andrey Konovalov
2021-03-08 16:24   ` Marco Elver
2021-03-08 16:24     ` Marco Elver
2021-03-08 15:55 ` [PATCH v2 5/5] kasan, mm: integrate slab init_on_free " Andrey Konovalov
2021-03-08 15:55   ` Andrey Konovalov
2021-03-08 16:27   ` Marco Elver
2021-03-08 16:27     ` Marco Elver

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