linux-kernel - Re: [PATCH] perf symbols: Ignore mapping symbols on riscv

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Message-ID: <CAJve8okP5wy-GNDCsDywgqPPmLSf0q1vGH573vXepxw7j-W8Qg@mail.gmail.com>
Date: Mon, 19 May 2025 16:13:58 +0800
From: Haibo Xu <xiaobo55x@...il.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Haibo Xu <haibo1.xu@...el.com>, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	"Liang, Kan" <kan.liang@...ux.intel.com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, Stephen Brennan <stephen.s.brennan@...cle.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-riscv@...ts.infradead.org
Subject: Re: [PATCH] perf symbols: Ignore mapping symbols on riscv

kindly ping.

Regards,
Haibo

On Fri, Apr 11, 2025 at 8:53 AM Namhyung Kim <namhyung@...nel.org> wrote:
>
> Hello,
>
> On Wed, Apr 09, 2025 at 10:51:56AM +0800, Haibo Xu wrote:
> > RISCV ELF use mapping symbols with special names $x, $d to
> > identify regions of RISCV code or code with different ISAs[1].
> > These symbols don't identify functions, so will confuse the
> > perf output.
> >
> > The patch filters out these symbols at load time, similar to
> > "4886f2ca perf symbols: Ignore mapping symbols on aarch64".
> >
> > [1] https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/
> >     master/riscv-elf.adoc#mapping-symbol
> >
> > Signed-off-by: Haibo Xu <haibo1.xu@...el.com>
>
> Acked-by: Namhyung Kim <namhyung@...nel.org>
>
> Thanks,
> Namhyung
>
>
> > ---
> >  tools/perf/util/symbol-elf.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> > index fbf6d0f73af9..55b1409b0593 100644
> > --- a/tools/perf/util/symbol-elf.c
> > +++ b/tools/perf/util/symbol-elf.c
> > @@ -1733,6 +1733,12 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
> >                               continue;
> >               }
> >
> > +             /* Reject RISCV ELF "mapping symbols" */
> > +             if (ehdr.e_machine == EM_RISCV) {
> > +                     if (elf_name[0] == '$' && strchr("dx", elf_name[1]))
> > +                             continue;
> > +             }
> > +
> >               if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) {
> >                       u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr;
> >                       u64 *opd = opddata->d_buf + offset;
> > --
> > 2.43.0
> >