Re: [PATCH v10 02/11] arm64: Make perf_callchain_kernel() use arch_stack_walk()

Madhavan T. Venkataraman
2021-10-21T12:28:54Z

On 10/20/21 9:59 AM, Mark Brown wrote:
> On Thu, Oct 14, 2021 at 09:58:38PM -0500, madvenka@linux.microsoft.com wrote:
>> From: "Madhavan T. Venkataraman" <madvenka@linux.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.
>
>> static bool callchain_trace(void *data, unsigned long pc)
>> {
>> struct perf_callchain_entry_ctx *entry = data;
>> - perf_callchain_store(entry, pc);
>> - return true;
>> + return perf_callchain_store(entry, pc) == 0;
>> }
>
> This changes us from unconditionally doing the whole walk to returning
> an error if perf_callchain_store() returns an error so it's not quite a
> straight transform, though since that seems like a useful improvement
> which most likely on't have any practical impact that's fine.
>
> Reviewed-by: Mark Brown <broonie@kernel.org>
>
>
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Thanks.

Madhavan