linux-kernel - Re: [PATCH 2/2] perf: disasm: prefer symsrc

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Message-ID: <6abf540f-5f11-4b2b-b8c1-69783a71277b@intel.com>
Date: Thu, 13 Jun 2024 13:26:39 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: duchangbin <changbin.du@...wei.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Nathan Chancellor <nathan@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
 "Liang, Kan" <kan.liang@...ux.intel.com>,
 Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling
 <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
 "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>
Subject: Re: [PATCH 2/2] perf: disasm: prefer symsrc_filename for filename

On 13/06/24 12:43, duchangbin wrote:
> On Thu, Jun 13, 2024 at 11:15:28AM +0300, Adrian Hunter wrote:
>> On 13/06/24 09:35, Changbin Du wrote:
>>> If we already found a debugging version when loading symbols for that dso,
>>> then use the same file for disasm instead of looking up in buildid-cache.
>>
>> In the past, there have been cases where the debugging version has not
>> worked for reading object code.  I don't remember the details, but the
>> symbols and debugging information was OK while the object code was not.
>>
>> In general, using anything other than the file that was actually executed
>> for reading object code seems like a bad idea.
>>
> Is this a platform specific issue? AFAIK, the binary code in debugging and
> non-debugging version should be identical. 

"should be" != "guaranteed to be".  Simpler to avoid the issue and
stick with the file that was actually executed.  We already support
having separate symbol sources, so there should not really be a
problem.