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Subject: Re: [PATCH v10 02/11] arm64: Make perf_callchain_kernel() use
 arch_stack_walk()
To:     Mark Brown <broonie@kernel.org>
Cc:     mark.rutland@arm.com, jpoimboe@redhat.com, ardb@kernel.org,
        nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com,
        catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org,
        linux-arm-kernel@lists.infradead.org,
        live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
References: <c05ce30dcc9be1bd6b5e24a2ca8fe1d66246980b>
 <20211015025847.17694-1-madvenka@linux.microsoft.com>
 <20211015025847.17694-3-madvenka@linux.microsoft.com>
 <YXAu2aXqBU3rO5e+@sirena.org.uk>
From:   "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
Message-ID: <f528a0d2-3fc5-771d-4249-cc1a9685d4ae@linux.microsoft.com>
Date:   Thu, 21 Oct 2021 07:28:46 -0500
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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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> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

Thanks.

Madhavan