Re: [PATCH 05/12] perf tools: Read also the end of the kernel

Jiri Olsa
2019-05-26T13:11:51Z

On Fri, May 24, 2019 at 03:46:07PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Fri, May 24, 2019 at 03:17:17PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Fri, May 24, 2019 at 03:15:06PM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Wed, May 08, 2019 at 03:20:03PM +0200, Jiri Olsa escreveu:
> > > > We mark the end of kernel based on the first module,
> > > > but that could cover some bpf program maps. Reading
> > > > _etext symbol if it's present to get precise kernel
> > > > map end.
> > >
> > > Investigating... Have you run 'perf test' before hitting the send
> > > button? :-)
> >
> > <SNIP>
> >
> > > [root@quaco c]# perf test -v 1
> > > 1: vmlinux symtab matches kallsyms :
> > <SNIP>
> > > --- start ---
> > > ERR : 0xffffffff8cc00e41: __indirect_thunk_end not on kallsyms
> > <SNIP>
> > > test child finished with -1
> > > ---- end ----
> > > vmlinux symtab matches kallsyms: FAILED!
> > > [root@quaco c]#
> >
> > So...
> >
> > [root@quaco c]# grep __indirect_thunk_end /proc/kallsyms
> > ffffffff8cc00e41 T __indirect_thunk_end
> > [root@quaco c]# grep -w _etext /proc/kallsyms
> > ffffffff8cc00e41 T _etext
> > [root@quaco c]#
> >
> > [root@quaco c]# grep -w ffffffff8cc00e41 /proc/kallsyms
> > ffffffff8cc00e41 T _etext
> > ffffffff8cc00e41 T __indirect_thunk_end
> > [root@quaco c]#
> >
> > Lemme try to fix this.
>
> So, I got this right before your patch:
>
> commit 1d1c54c5bbf55256e691bedb47b0d14745043e80
> Author: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date: Fri May 24 15:39:00 2019 -0300
>
> perf test vmlinux-kallsyms: Ignore aliases to _etext when searching on kallsyms
>
> No need to search for aliases for the symbol that marks the end of the
> kernel text segment, the following patch will make such symbols not to
> be found when searching in the kallsyms maps causing this test to fail.
>
> So as a prep patch to avoid breaking bisection, ignore such symbols.
>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Song Liu <songliubraving@fb.com>
> Cc: Stanislav Fomichev <sdf@google.com>
> Cc: Thomas Richter <tmricht@linux.ibm.com>
> Link: https://lkml.kernel.org/n/tip-qfwuih8cvmk9doh7k5k244eq@git.kernel.org
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

works for me

Tested-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka