linux-kernel - Re: [PATCH] perf test: Fix probe testsuite with a new error message

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Message-ID: <Zw8ddemrwX_mzQNJ@google.com>
Date: Tue, 15 Oct 2024 18:57:09 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Veronika Molnarova <vmolnaro@...hat.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Kan Liang <kan.liang@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users <linux-perf-users@...r.kernel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Michael Petlan <mpetlan@...hat.com>
Subject: Re: [PATCH] perf test: Fix probe testsuite with a new error message

Hello,

On Tue, Oct 15, 2024 at 12:46:35PM +0200, Veronika Molnarova wrote:
> 
> 
> On 10/10/24 16:40, Arnaldo Carvalho de Melo wrote:
> > On Thu, Oct 10, 2024, 10:31 AM Veronika Molnarova <vmolnaro@...hat.com>
> > wrote:
> > 
> >>
> >>
> >> On 10/10/24 14:50, Arnaldo Carvalho de Melo wrote:
> >>> On Thu, Oct 10, 2024 at 09:48:52AM -0300, Arnaldo Carvalho de Melo wrote:
> >>>> On Wed, Oct 09, 2024 at 10:16:20PM -0700, Namhyung Kim wrote:
> >>>>> On my system, it's constantly failing because of new error message from
> >>>>> perf probe.  It should update the regex pattern to match the message -
> >>>>> "A function DIE doesn't have decl_line. Maybe broken DWARF?".
> >>>>>
> >>>>>   $ sudo head -n 2 /sys/kernel/debug/kprobes/blacklist | cut -f2
> >>>>>   warn_thunk_thunk
> >>>>>   asm_exc_divide_error
> >>>>>
> >>>>>   $ sudo perf probe warn_thunk_thunk
> >>>>>   A function DIE doesn't have decl_line. Maybe broken DWARF?
> >>>>>   A function DIE doesn't have decl_line. Maybe broken DWARF?
> >>>>>   Probe point 'warn_thunk_thunk' not found.
> >>>>>     Error: Failed to add events.
> >>>>>
> >>>>>   $ sudo perf probe asm_exc_overflow
> >>>>>   Failed to find scope of probe point.
> >>>>>     Error: Failed to add events.
> >>>>
> >>>> We discussed this in the past, I came up with a similar patch, Veronika
> >>>> rightly pointed out that this may point to a real problem, Masami said
> >>>> that since these are for DWARF from assembly those are known issues, I
> >>>> suggested Veronika checked if the CU where the function came from was
> >>>> generated from Assembly (there are DWARF tags that have that info), IIRC
> >>>> she said she would try to do it.
> >>>>
> >>>> I'll try to find out the threads and see what happened.
> >>>
> >>> https://lore.kernel.org/all/ZvXhJLkJcR99Y2sF@google.com/T/#u
> >>>
> >>> Veronika, was there a v3?
> >>>
> >>> Thanks,
> >> Well the patch was already applied upstream so we are talking about a fix
> >> not v3, right?
> > 
> > 
> > 
> > 
> > Can you provide a url for the patch that was applied upstream?
> > 
> > I just checked at
> > 
> > https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/log/tools/perf/tests/shell/base_probe/test_adding_blacklisted.sh?h=perf-tools-next
> > 
> > And I'm not seeing it.
> 
> Well the patch adding the failing test case that you can see at
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/log/tools/perf/tests/shell/base_probe/test_adding_blacklisted.sh?h=perf-tools-next
> 
> There was the whole patchset that contained the failing probe test case.
> The patchset was applied and merged upstream so there won't be a v3 for 
> the failing test case, instead we will send a fix patch resolving the 
> mentioned issue. Hopefully this explains the confusion that I think
> happened.

Ok, thanks for the explanation.  I see it's merged already and I'm
waiting for the fix only.

> 
> We will send the next patchset soon containing also the patch fixing
> the probe issue with bad dwarf so if there will still be some confusion 
> that should resolve that.
 
It'd be nice if you can send the fix first separately.  As the whole
patchset might take some time for review, I want to fix the existing
problem ASAP.

Thanks,
Namhyung