linux-kernel - Re: [PATCH] arm64: stacktrace: don't trace arch_stack

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Message-Id: <161641697038.3900410.16800195752008718733.b4-ty@kernel.org>
Date:   Mon, 22 Mar 2021 13:19:56 +0000
From:   Will Deacon <will@...nel.org>
To:     linux-kernel@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     catalin.marinas@....com, kernel-team@...roid.com,
        Will Deacon <will@...nel.org>, Mark Brown <broonie@...nel.org>,
        Marco Elver <elver@...gle.com>,
        Chen Jun <chenjun102@...wei.com>
Subject: Re: [PATCH] arm64: stacktrace: don't trace arch_stack_walk()

On Fri, 19 Mar 2021 18:41:06 +0000, Mark Rutland wrote:
> We recently converted arm64 to use arch_stack_walk() in commit:
> 
>   5fc57df2f6fd ("arm64: stacktrace: Convert to ARCH_STACKWALK")
> 
> The core stacktrace code expects that (when tracing the current task)
> arch_stack_walk() starts a trace at its caller, and does not include
> itself in the trace. However, arm64's arch_stack_walk() includes itself,
> and so traces include one more entry than callers expect. The core
> stacktrace code which calls arch_stack_walk() tries to skip a number of
> entries to prevent itself appearing in a trace, and the additional entry
> prevents skipping one of the core stacktrace functions, leaving this in
> the trace unexpectedly.
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64: stacktrace: don't trace arch_stack_walk()
      https://git.kernel.org/arm64/c/c607ab4f916d

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev