From: Catalin Marinas <catalin.marinas@arm.com>
To: linux-arm-kernel@lists.infradead.org,
D Scott Phillips <scott@os.amperecomputing.com>
Cc: Will Deacon <will@kernel.org>,
patches@amperecomputing.com,
Darren Hart <darren@os.amperecomputing.com>,
Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH v5] arm64: errata: Fix exec handling in erratum 1418040 workaround
Date: Wed, 22 Dec 2021 15:23:34 +0000 [thread overview]
Message-ID: <164018659839.257110.10503084732579119152.b4-ty@arm.com> (raw)
In-Reply-To: <20211220234114.3926-1-scott@os.amperecomputing.com>
On Mon, 20 Dec 2021 15:41:14 -0800, D Scott Phillips wrote:
> The erratum 1418040 workaround enables CNTVCT_EL1 access trapping in EL0
> when executing compat threads. The workaround is applied when switching
> between tasks, but the need for the workaround could also change at an
> exec(), when a non-compat task execs a compat binary or vice versa. Apply
> the workaround in arch_setup_new_exec().
>
> This leaves a small window of time between SET_PERSONALITY and
> arch_setup_new_exec where preemption could occur and confuse the old
> workaround logic that compares TIF_32BIT between prev and next. Instead, we
> can just read cntkctl to make sure it's in the state that the next task
> needs. I measured cntkctl read time to be about the same as a mov from a
> general-purpose register on N1. Update the workaround logic to examine the
> current value of cntkctl instead of the previous task's compat state.
>
> [...]
Applied to arm64 (for-next/misc), thanks!
[1/1] arm64: errata: Fix exec handling in erratum 1418040 workaround
https://git.kernel.org/arm64/c/38e0257e0e6f
--
Catalin
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next prev parent reply other threads:[~2021-12-22 15:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 23:41 [PATCH v5] arm64: errata: Fix exec handling in erratum 1418040 workaround D Scott Phillips
2021-12-21 11:30 ` Catalin Marinas
2021-12-21 20:10 ` D Scott Phillips
2021-12-22 11:03 ` Catalin Marinas
2021-12-22 12:44 ` Marc Zyngier
2021-12-22 15:23 ` Catalin Marinas [this message]
2021-12-22 15:25 ` Catalin Marinas
2021-12-22 16:12 ` D Scott Phillips
2021-12-23 11:43 ` Catalin Marinas
2021-12-23 18:22 ` D Scott Phillips
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