From: Michael Ellerman <mpe@ellerman.id.au> To: Namhyung Kim <namhyung@kernel.org>, Jiri Slaby <jslaby@suse.cz> Cc: Jiri Olsa <jolsa@redhat.com>, Arnaldo Carvalho de Melo <acme@kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, Mark Rutland <mark.rutland@arm.com>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] perf tools: Resolve symbols against debug file first Date: Thu, 14 Jan 2021 22:17:25 +1100 [thread overview] Message-ID: <87sg73kbsq.fsf@mpe.ellerman.id.au> (raw) In-Reply-To: <CAM9d7cgmUqLX+C1wDPe9qaxDh1tY4sVmLx2qZqey3CQSmZSo2Q@mail.gmail.com> Namhyung Kim <namhyung@kernel.org> writes: > On Wed, Jan 13, 2021 at 8:43 PM Jiri Slaby <jslaby@suse.cz> wrote: >> >> On 13. 01. 21, 11:46, Jiri Olsa wrote: >> > On Wed, Jan 13, 2021 at 09:01:28AM +0100, Jiri Slaby wrote: >> >> With LTO, there are symbols like these: >> >> /usr/lib/debug/usr/lib64/libantlr4-runtime.so.4.8-4.8-1.4.x86_64.debug >> >> 10305: 0000000000955fa4 0 NOTYPE LOCAL DEFAULT 29 Predicate.cpp.2bc410e7 >> >> >> >> This comes from a runtime/debug split done by the standard way: >> >> objcopy --only-keep-debug $runtime $debug >> >> objcopy --add-gnu-debuglink=$debugfn -R .comment -R .GCC.command.line --strip-all $runtime >> >> ... >> >> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c >> >> index f3577f7d72fe..a31b716fa61c 100644 >> >> --- a/tools/perf/util/symbol-elf.c >> >> +++ b/tools/perf/util/symbol-elf.c >> >> @@ -1226,12 +1226,20 @@ int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss, >> >> if (sym.st_shndx == SHN_ABS) >> >> continue; >> >> >> >> - sec = elf_getscn(runtime_ss->elf, sym.st_shndx); >> >> + sec = elf_getscn(syms_ss->elf, sym.st_shndx); >> >> if (!sec) >> >> goto out_elf_end; >> > >> > we iterate symbols from syms_ss, so the fix seems to be correct >> > to call elf_getscn on syms_ss, not on runtime_ss as we do now >> > >> > I'd think this worked only when runtime_ss == syms_ss >> >> No, because the headers are copied 1:1 from runtime_ss to syms_ss. And >> runtime_ss is then stripped, so only .debug* sections are removed there. >> (And syms_ss's are set as NOBITS.) >> >> We iterated .debug* sections in syms_ss and used runtime_ss section >> _headers_ only to adjust symbols (sometimes). That worked. > > It seems PPC has an opd section only in the runtime_ss and that's why > we use it for section headers. At least on my system (Ubuntu 20.04.1) I see .opd in the debug file with NOBITS set: $ readelf -e vmlinux.debug | grep opd [37] .opd NOBITS c000000001c1f548 01202e14 But possibly that's not the case with older toolchains? cheers
WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <mpe@ellerman.id.au> To: Namhyung Kim <namhyung@kernel.org>, Jiri Slaby <jslaby@suse.cz> Cc: Mark Rutland <mark.rutland@arm.com>, Peter Zijlstra <peterz@infradead.org>, linuxppc-dev@lists.ozlabs.org, linux-kernel <linux-kernel@vger.kernel.org>, Arnaldo Carvalho de Melo <acme@kernel.org>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, Ingo Molnar <mingo@redhat.com>, Jiri Olsa <jolsa@redhat.com> Subject: Re: [PATCH] perf tools: Resolve symbols against debug file first Date: Thu, 14 Jan 2021 22:17:25 +1100 [thread overview] Message-ID: <87sg73kbsq.fsf@mpe.ellerman.id.au> (raw) In-Reply-To: <CAM9d7cgmUqLX+C1wDPe9qaxDh1tY4sVmLx2qZqey3CQSmZSo2Q@mail.gmail.com> Namhyung Kim <namhyung@kernel.org> writes: > On Wed, Jan 13, 2021 at 8:43 PM Jiri Slaby <jslaby@suse.cz> wrote: >> >> On 13. 01. 21, 11:46, Jiri Olsa wrote: >> > On Wed, Jan 13, 2021 at 09:01:28AM +0100, Jiri Slaby wrote: >> >> With LTO, there are symbols like these: >> >> /usr/lib/debug/usr/lib64/libantlr4-runtime.so.4.8-4.8-1.4.x86_64.debug >> >> 10305: 0000000000955fa4 0 NOTYPE LOCAL DEFAULT 29 Predicate.cpp.2bc410e7 >> >> >> >> This comes from a runtime/debug split done by the standard way: >> >> objcopy --only-keep-debug $runtime $debug >> >> objcopy --add-gnu-debuglink=$debugfn -R .comment -R .GCC.command.line --strip-all $runtime >> >> ... >> >> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c >> >> index f3577f7d72fe..a31b716fa61c 100644 >> >> --- a/tools/perf/util/symbol-elf.c >> >> +++ b/tools/perf/util/symbol-elf.c >> >> @@ -1226,12 +1226,20 @@ int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss, >> >> if (sym.st_shndx == SHN_ABS) >> >> continue; >> >> >> >> - sec = elf_getscn(runtime_ss->elf, sym.st_shndx); >> >> + sec = elf_getscn(syms_ss->elf, sym.st_shndx); >> >> if (!sec) >> >> goto out_elf_end; >> > >> > we iterate symbols from syms_ss, so the fix seems to be correct >> > to call elf_getscn on syms_ss, not on runtime_ss as we do now >> > >> > I'd think this worked only when runtime_ss == syms_ss >> >> No, because the headers are copied 1:1 from runtime_ss to syms_ss. And >> runtime_ss is then stripped, so only .debug* sections are removed there. >> (And syms_ss's are set as NOBITS.) >> >> We iterated .debug* sections in syms_ss and used runtime_ss section >> _headers_ only to adjust symbols (sometimes). That worked. > > It seems PPC has an opd section only in the runtime_ss and that's why > we use it for section headers. At least on my system (Ubuntu 20.04.1) I see .opd in the debug file with NOBITS set: $ readelf -e vmlinux.debug | grep opd [37] .opd NOBITS c000000001c1f548 01202e14 But possibly that's not the case with older toolchains? cheers
next prev parent reply other threads:[~2021-01-14 11:18 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-13 8:01 [PATCH] perf tools: Resolve symbols against debug file first Jiri Slaby 2021-01-13 10:46 ` Jiri Olsa 2021-01-13 11:43 ` Jiri Slaby 2021-01-14 4:54 ` Namhyung Kim 2021-01-14 4:54 ` Namhyung Kim 2021-01-14 11:17 ` Michael Ellerman [this message] 2021-01-14 11:17 ` Michael Ellerman 2021-01-15 7:37 ` Namhyung Kim 2021-01-15 7:37 ` Namhyung Kim 2021-01-28 10:43 ` Jiri Slaby 2021-02-03 4:28 ` Namhyung Kim 2021-02-03 19:32 ` Jiri Olsa
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=87sg73kbsq.fsf@mpe.ellerman.id.au \ --to=mpe@ellerman.id.au \ --cc=acme@kernel.org \ --cc=alexander.shishkin@linux.intel.com \ --cc=jolsa@redhat.com \ --cc=jslaby@suse.cz \ --cc=linux-kernel@vger.kernel.org \ --cc=linuxppc-dev@lists.ozlabs.org \ --cc=mark.rutland@arm.com \ --cc=mingo@redhat.com \ --cc=namhyung@kernel.org \ --cc=peterz@infradead.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.