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From: Ravi Bangoria <ravi.bangoria@amd.com>
To: Adrian Hunter <adrian.hunter@intel.com>, acme@kernel.org
Cc: jolsa@kernel.org, namhyung@kernel.org, irogers@google.com,
	kan.liang@linux.intel.com, peterz@infradead.org,
	mark.rutland@arm.com, mingo@redhat.com,
	alexander.shishkin@linux.intel.com, james.clark@arm.com,
	german.gomez@arm.com, leo.yan@linaro.org,
	alexey.v.bayduraev@linux.intel.com,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	sandipan.das@amd.com, ananth.narayan@amd.com,
	santosh.shukla@amd.com, Ravi Bangoria <ravi.bangoria@amd.com>
Subject: Re: [RFC 0/4] perf tool: Fix non-".text" symbol resolution for kernel modules
Date: Tue, 10 Jan 2023 14:13:53 +0530	[thread overview]
Message-ID: <760acfd9-26a0-e028-bc29-004be0b2620c@amd.com> (raw)
In-Reply-To: <86f43058-a51a-42c7-4d75-564f0e8eef04@intel.com>

Hi Adrian,

On 10-Jan-23 12:05 PM, Adrian Hunter wrote:
> On 10/01/23 07:58, Ravi Bangoria wrote:
>> Kernel module elf contains executable code in non-".text" sections as
>> well, for ex: ".noinstr.text". Plus, kernel module's memory layout
>> differs from it's binary layout because .ko elf does not contain
>> program header table.
> 
> Have you looked at using perf record --kcore option.

Nice! We can also use --kallsyms with perf report and it resolves symbols
fine.

But what about normal perf record/report? Why I'm enforcing on normal perf-
record/report is because, generally user don't specify these options, esp if
he has root privileges, he expects symbol-resolution should just work fine.
But when he sees inconsistency in symbol-resolution of the same kernel module,
he will be clueless of what's missing. This patchset is trying to solve it,
although I too feel adding section specific maps to perf.data is overkill as
--kcore or --kallsyms can also resolve those symbols.

Thanks for your feedback,
Ravi

  reply	other threads:[~2023-01-10  8:44 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-10  5:58 Ravi Bangoria
2023-01-10  5:58 ` [RFC 1/4] perf tool: Simplify machine__create_modules() a bit Ravi Bangoria
2023-01-10  5:58 ` [RFC 2/4] perf tool: Refactor perf_event__synthesize_modules() Ravi Bangoria
2023-01-10  5:58 ` [RFC 3/4] perf tool: Introduce PERF_RECORD_KMOD_SEC_MAP Ravi Bangoria
2023-01-16  6:14   ` Adrian Hunter
2023-01-16 13:34     ` Ravi Bangoria
2023-01-10  5:58 ` [RFC 4/4] perf tool: Fix non-".text" symbol resolution for kernel modules Ravi Bangoria
2023-02-07  7:35   ` kernel test robot
2023-01-10  6:35 ` [RFC 0/4] " Adrian Hunter
2023-01-10  8:43   ` Ravi Bangoria [this message]
2023-01-10  8:58     ` Ravi Bangoria
2023-01-16  4:21 ` Ravi Bangoria

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