From: Catalin Marinas <catalin.marinas@arm.com>
To: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Brown <broonie@kernel.org>, 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: Wed, 2 Mar 2022 11:44:53 +0000 [thread overview]
Message-ID: <Yh9Ytbeywua1tL0b@arm.com> (raw)
In-Reply-To: <Yh6/sU5YSTz8FdDG@google.com>
On Tue, Mar 01, 2022 at 04:52:01PM -0800, Evgenii Stepanov wrote:
> 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.
But if the app is compiled against an old version, it wouldn't set
MTE_CTRL_TCF_ASYMM either as it doesn't have the definition.
--
Catalin
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next prev parent reply other threads:[~2022-03-02 11:46 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
2022-03-02 11:44 ` Catalin Marinas [this message]
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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