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From: Evgenii Stepanov <eugenis@google.com>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
	Branislav Rankov <branislav.rankov@arm.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v1 4/4] arm64/mte: Add userspace interface for enabling asymmetric mode
Date: Tue, 1 Mar 2022 16:52:01 -0800	[thread overview]
Message-ID: <Yh6/sU5YSTz8FdDG@google.com> (raw)
In-Reply-To: <20220127195712.748150-5-broonie@kernel.org>

On Thu, Jan 27, 2022 at 07:57:12PM +0000, Mark Brown wrote:
> Since there PR_MTE_TCF_ values are a bitmask (allowing the kernel to choose
> between the multiple modes) and there are no free bits adjacent to the
> existing PR_MTE_TCF_ bits the set of bits used to specify the mode becomes
> disjoint. Programs using the new interface should be aware of this and
> programs that do not use it will not see any change in behaviour.

Extending PR_MTE_TCF_MASK seems bad for backward compatibility. User
code may do "flags =& ~PR_MTE_TCF_MASK" to disable MTE; when compiled
against an old version of the header this would fail to remove the ASYMM
bit.


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  parent reply	other threads:[~2022-03-02  0:54 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-27 19:57 [PATCH v1 0/4] arm64/mte: Asymmetric MTE support in userspace Mark Brown
2022-01-27 19:57 ` [PATCH v1 1/4] arm64/mte: Document ABI for asymmetric mode Mark Brown
2022-01-28 16:43   ` Catalin Marinas
2022-01-28 17:23     ` Mark Brown
2022-01-28 16:55   ` Vincenzo Frascino
2022-02-15 18:14   ` Will Deacon
2022-02-16 16:36     ` Mark Brown
2022-02-16 17:06       ` Will Deacon
2022-01-27 19:57 ` [PATCH v1 2/4] arm64/mte: Add a little bit of documentation for mte_update_sctlr_user() Mark Brown
2022-01-28 16:45   ` Catalin Marinas
2022-01-28 16:57   ` Vincenzo Frascino
2022-01-27 19:57 ` [PATCH v1 3/4] arm64/mte: Add hwcap for asymmetric mode Mark Brown
2022-01-28 16:51   ` Catalin Marinas
2022-01-28 17:00   ` Vincenzo Frascino
2022-01-27 19:57 ` [PATCH v1 4/4] arm64/mte: Add userspace interface for enabling " Mark Brown
2022-01-28 17:12   ` Vincenzo Frascino
2022-01-28 17:15   ` Catalin Marinas
2022-03-02  0:52   ` Evgenii Stepanov [this message]
2022-03-02 11:44     ` Catalin Marinas
2022-03-02 13:10       ` Mark Brown
2022-03-02 18:44         ` Evgenii Stepanov
2022-03-02 19:33           ` Mark Brown
2022-03-02 20:58             ` Evgenii Stepanov
2022-03-03 10:34               ` Catalin Marinas
2022-03-03 15:44                 ` Mark Brown
2022-03-03 22:47                   ` Evgenii Stepanov
2022-03-04 21:09                 ` Peter Collingbourne
2022-03-07 15:36                   ` Catalin Marinas
2022-03-07 19:10                     ` Mark Brown
2022-03-07 20:55                       ` Peter Collingbourne
2022-03-08 13:34                         ` Mark Brown
2022-03-07 20:55                     ` Peter Collingbourne
2022-03-08 18:26                       ` Catalin Marinas
2022-02-10 21:43 ` [PATCH v1 0/4] arm64/mte: Asymmetric MTE support in userspace Branislav Rankov

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