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From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Dmitry Vyukov <dvyukov@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Branislav Rankov <Branislav.Rankov@arm.com>,
	Andrey Konovalov <andreyknvl@google.com>
Subject: Re: [PATCH v3 4/4] arm64: mte: Optimize mte_assign_mem_tag_range()
Date: Sun, 17 Jan 2021 12:27:08 +0000	[thread overview]
Message-ID: <0c1b9a6b-0326-a24f-6418-23a0723adecf@arm.com> (raw)
In-Reply-To: <4b1a5cdf-e1bf-3a7e-593f-0089cedbbc03@arm.com>

Hi Mark,

On 1/16/21 2:22 PM, Vincenzo Frascino wrote:
>> Is there any chance that this can be used for the last bytes of the
>> virtual address space? This might need to change to `_addr == _end` if
>> that is possible, otherwise it'll terminate early in that case.
>>
> Theoretically it is a possibility. I will change the condition and add a note
> for that.
> 

I was thinking to the end of the virtual address space scenario and I forgot
that if I use a condition like `_addr == _end` the tagging operation overflows
to the first granule of the next allocation. This disrupts tagging accesses for
that memory area hence I think that `_addr < _end` is the way to go.

-- 
Regards,
Vincenzo

WARNING: multiple messages have this Message-ID (diff)
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>,
	Marco Elver <elver@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Evgenii Stepanov <eugenis@google.com>,
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
	Alexander Potapenko <glider@google.com>,
	linux-arm-kernel@lists.infradead.org,
	Andrey Konovalov <andreyknvl@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Will Deacon <will@kernel.org>, Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH v3 4/4] arm64: mte: Optimize mte_assign_mem_tag_range()
Date: Sun, 17 Jan 2021 12:27:08 +0000	[thread overview]
Message-ID: <0c1b9a6b-0326-a24f-6418-23a0723adecf@arm.com> (raw)
In-Reply-To: <4b1a5cdf-e1bf-3a7e-593f-0089cedbbc03@arm.com>

Hi Mark,

On 1/16/21 2:22 PM, Vincenzo Frascino wrote:
>> Is there any chance that this can be used for the last bytes of the
>> virtual address space? This might need to change to `_addr == _end` if
>> that is possible, otherwise it'll terminate early in that case.
>>
> Theoretically it is a possibility. I will change the condition and add a note
> for that.
> 

I was thinking to the end of the virtual address space scenario and I forgot
that if I use a condition like `_addr == _end` the tagging operation overflows
to the first granule of the next allocation. This disrupts tagging accesses for
that memory area hence I think that `_addr < _end` is the way to go.

-- 
Regards,
Vincenzo

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

  reply	other threads:[~2021-01-17 12:27 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-15 12:00 [PATCH v3 0/4] arm64: ARMv8.5-A: MTE: Add async mode support Vincenzo Frascino
2021-01-15 12:00 ` Vincenzo Frascino
2021-01-15 12:00 ` [PATCH v3 1/4] kasan, arm64: Add KASAN light mode Vincenzo Frascino
2021-01-15 12:00   ` Vincenzo Frascino
2021-01-15 15:08   ` Mark Rutland
2021-01-15 15:08     ` Mark Rutland
2021-01-16 13:47     ` Vincenzo Frascino
2021-01-16 13:47       ` Vincenzo Frascino
2021-01-16 14:09       ` Andrey Konovalov
2021-01-16 14:09         ` Andrey Konovalov
2021-01-18 10:24       ` Mark Rutland
2021-01-18 10:24         ` Mark Rutland
2021-01-15 18:59   ` Andrey Konovalov
2021-01-15 18:59     ` Andrey Konovalov
2021-01-16 13:40     ` Vincenzo Frascino
2021-01-16 13:40       ` Vincenzo Frascino
2021-01-16 13:59       ` Andrey Konovalov
2021-01-16 13:59         ` Andrey Konovalov
2021-01-16 14:06         ` Vincenzo Frascino
2021-01-16 14:06           ` Vincenzo Frascino
2021-01-15 12:00 ` [PATCH v3 2/4] arm64: mte: Add asynchronous mode support Vincenzo Frascino
2021-01-15 12:00   ` Vincenzo Frascino
2021-01-15 15:13   ` Mark Rutland
2021-01-15 15:13     ` Mark Rutland
2021-01-16 13:49     ` Vincenzo Frascino
2021-01-16 13:49       ` Vincenzo Frascino
2021-01-15 12:00 ` [PATCH v3 3/4] arm64: mte: Enable async tag check fault Vincenzo Frascino
2021-01-15 12:00   ` Vincenzo Frascino
2021-01-15 15:37   ` Mark Rutland
2021-01-15 15:37     ` Mark Rutland
2021-01-18 12:57   ` Catalin Marinas
2021-01-18 12:57     ` Catalin Marinas
2021-01-18 13:37     ` Vincenzo Frascino
2021-01-18 13:37       ` Vincenzo Frascino
2021-01-18 14:14       ` Mark Rutland
2021-01-18 14:14         ` Mark Rutland
2021-01-18 14:48         ` Vincenzo Frascino
2021-01-18 14:48           ` Vincenzo Frascino
2021-01-18 15:39           ` Vincenzo Frascino
2021-01-18 15:39             ` Vincenzo Frascino
2021-01-18 15:40       ` Vincenzo Frascino
2021-01-18 15:40         ` Vincenzo Frascino
2021-01-15 12:00 ` [PATCH v3 4/4] arm64: mte: Optimize mte_assign_mem_tag_range() Vincenzo Frascino
2021-01-15 12:00   ` Vincenzo Frascino
2021-01-15 15:45   ` Mark Rutland
2021-01-15 15:45     ` Mark Rutland
2021-01-16 14:22     ` Vincenzo Frascino
2021-01-16 14:22       ` Vincenzo Frascino
2021-01-17 12:27       ` Vincenzo Frascino [this message]
2021-01-17 12:27         ` Vincenzo Frascino
2021-01-18 10:41         ` Mark Rutland
2021-01-18 10:41           ` Mark Rutland
2021-01-18 11:00           ` Vincenzo Frascino
2021-01-18 11:00             ` Vincenzo Frascino

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