linux-kernel - Re: [PATCH 1/1 perf-tools-next] perf top: Don't complain about lack of vmlinux when not resolving some kernel samples

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Message-ID: <Z37d_pEDFJzw5u5R@x1>
Date: Wed, 8 Jan 2025 17:20:14 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Ian Rogers <irogers@...gle.com>,
	James Clark <james.clark@...aro.org>, Jiri Olsa <jolsa@...nel.org>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 1/1 perf-tools-next] perf top: Don't complain about lack
 of vmlinux when not resolving some kernel samples

On Mon, Jan 06, 2025 at 01:04:45PM -0800, Namhyung Kim wrote:
> Hi Arnaldo,
> 
> On Fri, Jan 03, 2025 at 01:47:19PM -0300, Arnaldo Carvalho de Melo wrote:
> > Recently we got a case where a kernel sample wasn't being resolved due
> > to a bug that was not setting the end address on kernel functions
> > implemented in assembly (see Link: tag), and then those were not being
> > found by machine__resolve() -> map__find_symbol().
> > 
> > So we ended up with:
> > 
> >   # perf top --stdio
> >   PerfTop: 0 irqs/s  kernel: 0%  exact: 0% lost: 0/0 drop: 0/0 [cycles/P]
> >   -----------------------------------------------------------------------
> > 
> >   Warning:
> >   A vmlinux file was not found.
> >   Kernel samples will not be resolved.
> >   ^Z
> >   [1]+  Stopped                 perf top --stdio
> >   #
> > 
> > But then resolving all other kernel symbols.
> > 
> > So just fixup the logic to only print that warning when there are no
> > symbols in the kernel map.
> > 
> > Cc: Adrian Hunter <adrian.hunter@...el.com>
> > Cc: Ian Rogers <irogers@...gle.com>
> > Cc: Christophe Leroy <christophe.leroy@...roup.eu>
> > Cc: James Clark <james.clark@...aro.org>
> > Cc: Jiri Olsa <jolsa@...nel.org>
> > Cc: Kan Liang <kan.liang@...ux.intel.com>
> > Link: https://lore.kernel.org/lkml/Z3buKhcCsZi3_aGb@x1
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> 
> Reviewed-by: Namhyung Kim <namhyung@...nel.org>
> 
> Looks like an old bug since d88205db9caa0e9d ("perf dso: Add
> dso__has_symbols() method"). :)

Agreed, logic inversion, I'm adding the Fixes tag, thanks for finding
it!

- Arnaldo