From: Will Deacon <will@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>,
Mark Brown <broonie@kernel.org>
Cc: kernel-team@android.com, Will Deacon <will@kernel.org>,
D Scott Phillips <scott@os.amperecomputing.com>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] arm64/bti: Disable in kernel BTI when cross section thunks are broken
Date: Tue, 6 Sep 2022 13:17:21 +0100 [thread overview]
Message-ID: <166245100774.1026830.8110650974197966709.b4-ty@kernel.org> (raw)
In-Reply-To: <20220905142255.591990-1-broonie@kernel.org>
On Mon, 5 Sep 2022 15:22:55 +0100, Mark Brown wrote:
> GCC does not insert a `bti c` instruction at the beginning of a function
> when it believes that all callers reach the function through a direct
> branch[1]. Unfortunately the logic it uses to determine this is not
> sufficiently robust, for example not taking account of functions being
> placed in different sections which may be loaded separately, so we may
> still see thunks being generated to these functions. If that happens,
> the first instruction in the callee function will result in a Branch
> Target Exception due to the missing landing pad.
>
> [...]
Applied to arm64 (for-next/fixes), thanks!
[1/1] arm64/bti: Disable in kernel BTI when cross section thunks are broken
https://git.kernel.org/arm64/c/c0a454b9044f
Cheers,
--
Will
https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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prev parent reply other threads:[~2022-09-06 12:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-05 14:22 [PATCH v2] arm64/bti: Disable in kernel BTI when cross section thunks are broken Mark Brown
2022-09-06 12:17 ` Will Deacon [this message]
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