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Date:   Tue, 10 Jan 2023 14:13:53 +0530
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From:   Ravi Bangoria <ravi.bangoria@amd.com>
Subject: Re: [RFC 0/4] perf tool: Fix non-".text" symbol resolution for kernel
 modules
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>
References: <20230110055859.685-1-ravi.bangoria@amd.com>
 <86f43058-a51a-42c7-4d75-564f0e8eef04@intel.com>
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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