From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: Symbols not found for some files
Date: Wed, 3 Oct 2018 17:57:25 -0300 [thread overview]
Message-ID: <20181003205725.GD11343@kernel.org> (raw)
In-Reply-To: <c5e4d596-0805-a45e-b6b2-cda43c9f6953@molgen.mpg.de>
Em Wed, Oct 03, 2018 at 10:42:39PM +0200, Paul Menzel escreveu:
> Dear Linux folks,
>
>
> For profiling the boot on my Debian Sid/unstable system (32-bit user space),
> the following service unit is used.
You forgot to mention what is the version of the perf tool in that
system, so that I could check if this got fixed somehow after that
version.
Can you please provide it?
Thanks,
- Arnaldo
> ```
> $ systemctl cat perf
> # /etc/systemd/system/perf.service
>
> [Unit]
> Description=Perf 10 s
> DefaultDependencies=no
>
> [Service]
> ExecStart=/usr/local/bin/perf record -F 999 -g -a -o /dev/shm/perf.data
> sleep 10
>
> [Install]
> WantedBy=sysinit.target
> ```
>
> Running `perf.data` through `perf script`, the messages below are shown.
>
> ```
> [vdso] with build id 69dd0f0c522f0d3e2a87722d70245ab9725c8b42 not found,
> continuing without symbols
> /lib/systemd/libsystemd-shared-239.so with build id
> 196c7922a15fa971d68775522dd16e82da46ebb3 not found, continuing without
> symbols
> /lib/systemd/systemd-journald with build id
> 9e31591e8c9bb88de06e96a251f34d8a7e201f6c not found, continuing without
> symbols
> /lib/systemd/systemd with build id 1b92f342a959b6ff370b82092bfadaf1d470a7b9
> not found, continuing without symbols
> /lib/systemd/systemd-networkd with build id
> 9fa8f6abc1f2e5c1018d0a33be058c22e25efaff not found, continuing without
> symbols
> /lib/systemd/systemd-logind with build id
> 63d664b5f8f8e85274aff6730ec9e924d74c8fed not found, continuing without
> symbols
> ```
>
> But, the debug symbol packages are installed (`systemd-dbgsym`), and GDB
> loads the debug symbols just fine.
>
> ```
> $ gdb --quiet /lib/systemd/libsystemd-shared-239.so
> Reading symbols from /lib/systemd/libsystemd-shared-239.so...Reading symbols
> from /usr/lib/debug/.build-id/19/6c7922a15fa971d68775522dd16e82da46ebb3.debug...done.
> done.
> (gdb)
> ```
>
> Tracing `perf`, it also seems to find them, but does not use them.
>
> ```
> stat64("/home/kodi/.debug/.build-id/a2/03af6935d5ab00f79fe12b4098d27d3f70c19f",
> 0xbfbd54ac) = -1 ENOENT (No such file or directory)
> stat64("/home/kodi/.debug/.build-id/a2/03af6935d5ab00f79fe12b4098d27d3f70c19f/elf",
> 0xbfbd75bc) = -1 ENOENT (No such file or directory)
> stat64("03af6935d5ab00f79fe12b4098d27d3f70c19f.debug", 0xbfbd1bfc) = -1
> ENOENT (No such file or directory)
> stat64("/lib/i386-linux-gnu/03af6935d5ab00f79fe12b4098d27d3f70c19f.debug",
> 0xbfbd1bfc) = -1 ENOENT (No such file or directory)
> stat64("/lib/i386-linux-gnu/.debug/03af6935d5ab00f79fe12b4098d27d3f70c19f.debug",
> 0xbfbd1bfc) = -1 ENOENT (No such file or directory)
> stat64("/usr/lib/debug/lib/i386-linux-gnu/03af6935d5ab00f79fe12b4098d27d3f70c19f.debug",
> 0xbfbd1bfc) = -1 ENOENT (No such file or directory)
> stat64("/home/kodi/.debug/.build-id/a2/03af6935d5ab00f79fe12b4098d27d3f70c19f",
> 0xbfbd1b5c) = -1 ENOENT (No such file or directory)
> stat64("/home/kodi/.debug/.build-id/a2/03af6935d5ab00f79fe12b4098d27d3f70c19f/elf",
> 0xbfbd3c6c) = -1 ENOENT (No such file or directory)
> stat64("/home/kodi/.debug/.build-id/a2/03af6935d5ab00f79fe12b4098d27d3f70c19f",
> 0xbfbd1b5c) = -1 ENOENT (No such file or directory)
> stat64("/home/kodi/.debug/.build-id/a2/03af6935d5ab00f79fe12b4098d27d3f70c19f/debug",
> 0xbfbd3c6c) = -1 ENOENT (No such file or directory)
> stat64("/usr/lib/debug/.build-id/a2/03af6935d5ab00f79fe12b4098d27d3f70c19f.debug",
> {st_mode=S_IFREG|0644, st_size=4524336, ...}) = 0
> openat(AT_FDCWD,
> "/usr/lib/debug/.build-id/a2/03af6935d5ab00f79fe12b4098d27d3f70c19f.debug",
> O_RDONLY|O_LARGEFILE) = 91
> ```
>
> Looking into `perf` with GDB, the code in `util/symbol.c` below is not
> setting `runtime_ss`, because `symsrc__possibly_runtime(ss)` returns false.
> Then the for loop is not quit, and continues.
>
> ```
> if (!syms_ss && symsrc__has_symtab(ss)) {
> syms_ss = ss;
> next_slot = true;
> if (!dso->symsrc_filename)
> dso->symsrc_filename = strdup(name);
> }
>
> if (!runtime_ss && symsrc__possibly_runtime(ss)) {
> runtime_ss = ss;
> next_slot = true;
> }
>
> if (next_slot) {
> ss_pos++;
>
> if (syms_ss && runtime_ss)
> break;
> } else {
> symsrc__destroy(ss);
> }
>
> ```
>
> Do you have an idea, why the files from the systemd Debian package cause
> problems for `perf` but not GDB? The Debian maintainers mentioned, that LTO
> is enabled for the Debian package.
>
> Please tell me, if you need other information to look into the problem.
>
>
> Kind regards,
>
> Paul
next prev parent reply other threads:[~2018-10-03 20:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-03 20:42 Symbols not found for some files Paul Menzel
2018-10-03 20:57 ` Arnaldo Carvalho de Melo [this message]
2018-10-04 3:19 ` Paul Menzel
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