linux-kernel - Re: [PATCH v10 02/11] arm64: Make perf_callchain_kernel() use arch_stack

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Message-ID: <4de6800b-54fc-a74d-598f-80fc40924976@linux.microsoft.com>
Date:   Sat, 23 Oct 2021 07:49:11 -0500
From:   "Madhavan T. Venkataraman" <madvenka@...ux.microsoft.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     broonie@...nel.org, jpoimboe@...hat.com, ardb@...nel.org,
        nobuta.keiya@...itsu.com, sjitindarsingh@...il.com,
        catalin.marinas@....com, will@...nel.org, jmorris@...ei.org,
        linux-arm-kernel@...ts.infradead.org,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 02/11] arm64: Make perf_callchain_kernel() use
 arch_stack_walk()



On 10/22/21 1:11 PM, Mark Rutland wrote:
> On Thu, Oct 14, 2021 at 09:58:38PM -0500, madvenka@...ux.microsoft.com wrote:
>> From: "Madhavan T. Venkataraman" <madvenka@...ux.microsoft.com>
>>
>> Currently, perf_callchain_kernel() in ARM64 code walks the stack using
>> start_backtrace() and walk_stackframe(). Make it use arch_stack_walk()
>> instead. This makes maintenance easier.
>>
>> Signed-off-by: Madhavan T. Venkataraman <madvenka@...ux.microsoft.com>
> 
> This looks good to me; bailing out when perf_callchain_store() can't
> accept any more entries absolutely makes sense.
> 
> I gave this a spin with:
> 
> | #  perf record -g -c1 ls
> | #  perf report
> 
> ... and the recorded callchains look sane.
> 
> Reviewed-by: Mark Rutland <mark.rutland@....com>
> Tested-by: Mark Rutland <mark.rutland@....com>
> 

Thanks a lot!

> As mentioned on patch 1, I'd like to get this rebased atop Peter's
> untangling of ARCH_STACKWALK from STACKTRACE.
> 

Will do.

Thanks.

Madhavan