* Re: libdw dwarf unwind issue [not found] <20201103221709.GL3597846@krava> @ 2020-11-22 22:27 ` Jan Kratochvil 2020-11-23 22:12 ` Jiri Olsa 0 siblings, 1 reply; 6+ messages in thread From: Jan Kratochvil @ 2020-11-22 22:27 UTC (permalink / raw) To: Jiri Olsa Cc: Frank Ch. Eigler, Mark Wielaard, Arnaldo Carvalho de Melo, Milian Wolff, John Levon, Namhyung Kim, linux-perf-users [-- Attachment #1: Type: text/plain, Size: 2237 bytes --] On Tue, 03 Nov 2020 23:17:09 +0100, Jiri Olsa wrote: > When you compiled perf with libunwind, you get: > > $ make VF=1 > $ perf report -i perf.data --stdio > > # Children Self Trace output > # ........ ........ .............. > # > 100.00% 100.00% (5640789cdf50) > | > |--98.85%--0x7fc8eca0f554 > | main > | main_loop_wait > | qemu_poll_ns > | > --1.15%--0x7fc8ecdc2ea4 > iothread_run > aio_poll > qemu_poll_ns > > > When you compile perf with libdw, you get: > > $ make VF=1 NO_LIBUNWIND=1 > $ perf report -i perf.data --stdio > > # Children Self Trace output > # ........ ........ .............. > # > 100.00% 100.00% (5640789cdf50) > | > |--98.85%--0x45260879 > | qemu_poll_ns > | > --1.15%--qemu_poll_ns I get after the attached fix: # Children Self Trace output # ........ ........ .............. # 100.00% 100.00% (5640789cdf50) | |--98.85%--main | main_loop_wait | qemu_poll_ns | --1.15%--iothread_run aio_poll qemu_poll_ns > any idea why libdw is doing that? ;-) Because libdw was reporting separate debuginfo file as the main file: (lldb) p thread->process->dwfl->modulelist->main.name (char *) $1 = 0x0000000000b52490 "/home/jkratoch/.debug/.build-id/fc/d0111443729957fa8ef9511ff5dc3e9a5ccf9d/debug" (lldb) p thread->process->dwfl->modulelist->debug.name (char *) $2 = 0x0000000000000000 The correct way is to report the main ELF file as the main file: (lldb) p thread->process->dwfl->modulelist->main.name (char *) $1 = 0x0000000000b52490 "/home/jkratoch/.debug/.build-id/fc/d0111443729957fa8ef9511ff5dc3e9a5ccf9d/elf" (lldb) p thread->process->dwfl->modulelist->debug.name (char *) $2 = 0x0000000000000000 In some cases it may later fill-in even the ->debug.name with "/debug" filename. Jan Kratochvil [-- Attachment #2: libdw-unwind.patch --] [-- Type: text/plain, Size: 2120 bytes --] diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c index 7a3dbc259cec..5d66cafccde5 100644 --- a/tools/perf/util/unwind-libdw.c +++ b/tools/perf/util/unwind-libdw.c @@ -20,10 +20,28 @@ static char *debuginfo_path; +static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, + const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, + const char *file_name __maybe_unused, + const char *debuglink_file __maybe_unused, + GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) +{ + const struct dso *dso = *userdata; + char filename[PATH_MAX]; + + assert(dso); + + // We could also use dso->symsrc_filename but it may not be set yet. + if (dso__build_id_filename(dso, filename, sizeof(filename), true)) + *debuginfo_file_name = strdup(filename); + return -1; +} + static const Dwfl_Callbacks offline_callbacks = { - .find_debuginfo = dwfl_standard_find_debuginfo, + .find_debuginfo = __find_debuginfo, .debuginfo_path = &debuginfo_path, .section_address = dwfl_offline_section_address, + // .find_elf is not set as we use dwfl_report_elf() instead. }; static int __report_module(struct addr_location *al, u64 ip, @@ -46,16 +64,21 @@ static int __report_module(struct addr_location *al, u64 ip, mod = dwfl_addrmodule(ui->dwfl, ip); if (mod) { Dwarf_Addr s; + void **userdatap; - dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); + dwfl_module_info(mod, &userdatap, &s, NULL, NULL, NULL, NULL, NULL); + *userdatap = dso; if (s != al->map->start - al->map->pgoff) mod = 0; } - if (!mod) - mod = dwfl_report_elf(ui->dwfl, dso->short_name, - (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff, - false); + if (!mod) { + char filename[PATH_MAX]; + + if (dso__build_id_filename(dso, filename, sizeof(filename), false)) + mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, + al->map->start - al->map->pgoff, false); + } return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; } ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: libdw dwarf unwind issue 2020-11-22 22:27 ` libdw dwarf unwind issue Jan Kratochvil @ 2020-11-23 22:12 ` Jiri Olsa 2020-11-28 4:07 ` Jan Kratochvil 0 siblings, 1 reply; 6+ messages in thread From: Jiri Olsa @ 2020-11-23 22:12 UTC (permalink / raw) To: Jan Kratochvil Cc: Frank Ch. Eigler, Mark Wielaard, Arnaldo Carvalho de Melo, Milian Wolff, John Levon, Namhyung Kim, linux-perf-users On Sun, Nov 22, 2020 at 11:27:51PM +0100, Jan Kratochvil wrote: SNIP > --1.15%--iothread_run > aio_poll > qemu_poll_ns > > > > any idea why libdw is doing that? ;-) > > Because libdw was reporting separate debuginfo file as the main file: > > (lldb) p thread->process->dwfl->modulelist->main.name > (char *) $1 = 0x0000000000b52490 "/home/jkratoch/.debug/.build-id/fc/d0111443729957fa8ef9511ff5dc3e9a5ccf9d/debug" > (lldb) p thread->process->dwfl->modulelist->debug.name > (char *) $2 = 0x0000000000000000 > > The correct way is to report the main ELF file as the main file: > > (lldb) p thread->process->dwfl->modulelist->main.name > (char *) $1 = 0x0000000000b52490 "/home/jkratoch/.debug/.build-id/fc/d0111443729957fa8ef9511ff5dc3e9a5ccf9d/elf" > (lldb) p thread->process->dwfl->modulelist->debug.name > (char *) $2 = 0x0000000000000000 > > In some cases it may later fill-in even the ->debug.name with "/debug" filename. hi, it fixes the issue for me, but it breaks the dwarf test: 72: DWARF unwind : FAILED! [jolsa@krava perf]$ sudo ./perf test dwarf -v 72: DWARF unwind : --- start --- test child forked, pid 2084484 unwind: failed with 'No such file or directory' got wrong number of stack entries 0 != 8 test child finished with -1 ---- end ---- DWARF unwind: FAILED! thanks, jirka ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: libdw dwarf unwind issue 2020-11-23 22:12 ` Jiri Olsa @ 2020-11-28 4:07 ` Jan Kratochvil 2020-12-01 19:41 ` Jiri Olsa 0 siblings, 1 reply; 6+ messages in thread From: Jan Kratochvil @ 2020-11-28 4:07 UTC (permalink / raw) To: Jiri Olsa Cc: Frank Ch. Eigler, Mark Wielaard, Arnaldo Carvalho de Melo, Milian Wolff, John Levon, Namhyung Kim, linux-perf-users [-- Attachment #1: Type: text/plain, Size: 685 bytes --] On Mon, 23 Nov 2020 23:12:47 +0100, Jiri Olsa wrote: > it fixes the issue for me, but it breaks the dwarf test: > > 72: DWARF unwind : FAILED! > [jolsa@krava perf]$ sudo ./perf test dwarf -v > 72: DWARF unwind : > --- start --- > test child forked, pid 2084484 > unwind: failed with 'No such file or directory' > got wrong number of stack entries 0 != 8 > test child finished with -1 > ---- end ---- > DWARF unwind: FAILED! The previous patch required ~/.debug/ build-id symlink, fixed. I hope dso->symsrc_filename is always already set if a separate debug info is present. Jan [-- Attachment #2: libdw-unwind2.patch --] [-- Type: text/plain, Size: 2115 bytes --] diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c index 7a3dbc259cec..400e4832b50e 100644 --- a/tools/perf/util/unwind-libdw.c +++ b/tools/perf/util/unwind-libdw.c @@ -20,10 +20,25 @@ static char *debuginfo_path; +static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, + const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, + const char *file_name __maybe_unused, + const char *debuglink_file __maybe_unused, + GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) +{ + const struct dso *dso = *userdata; + + assert(dso); + if (dso->symsrc_filename) + *debuginfo_file_name = strdup(dso->symsrc_filename); + return -1; +} + static const Dwfl_Callbacks offline_callbacks = { - .find_debuginfo = dwfl_standard_find_debuginfo, + .find_debuginfo = __find_debuginfo, .debuginfo_path = &debuginfo_path, .section_address = dwfl_offline_section_address, + // .find_elf is not set as we use dwfl_report_elf() instead. }; static int __report_module(struct addr_location *al, u64 ip, @@ -46,16 +61,24 @@ static int __report_module(struct addr_location *al, u64 ip, mod = dwfl_addrmodule(ui->dwfl, ip); if (mod) { Dwarf_Addr s; + void **userdatap; - dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); + dwfl_module_info(mod, &userdatap, &s, NULL, NULL, NULL, NULL, NULL); + *userdatap = dso; if (s != al->map->start - al->map->pgoff) mod = 0; } if (!mod) - mod = dwfl_report_elf(ui->dwfl, dso->short_name, - (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff, - false); + mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1, + al->map->start - al->map->pgoff, false); + if (!mod) { + char filename[PATH_MAX]; + + if (dso__build_id_filename(dso, filename, sizeof(filename), false)) + mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, + al->map->start - al->map->pgoff, false); + } return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; } ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: libdw dwarf unwind issue 2020-11-28 4:07 ` Jan Kratochvil @ 2020-12-01 19:41 ` Jiri Olsa 2020-12-02 10:06 ` Jan Kratochvil 0 siblings, 1 reply; 6+ messages in thread From: Jiri Olsa @ 2020-12-01 19:41 UTC (permalink / raw) To: Jan Kratochvil Cc: Frank Ch. Eigler, Mark Wielaard, Arnaldo Carvalho de Melo, Milian Wolff, John Levon, Namhyung Kim, linux-perf-users On Sat, Nov 28, 2020 at 05:07:40AM +0100, Jan Kratochvil wrote: > On Mon, 23 Nov 2020 23:12:47 +0100, Jiri Olsa wrote: > > it fixes the issue for me, but it breaks the dwarf test: > > > > 72: DWARF unwind : FAILED! > > [jolsa@krava perf]$ sudo ./perf test dwarf -v > > 72: DWARF unwind : > > --- start --- > > test child forked, pid 2084484 > > unwind: failed with 'No such file or directory' > > got wrong number of stack entries 0 != 8 > > test child finished with -1 > > ---- end ---- > > DWARF unwind: FAILED! > > The previous patch required ~/.debug/ build-id symlink, fixed. > > I hope dso->symsrc_filename is always already set if a separate debug info is > present. it should be the one with .symtab section the fix is working for me, would you mind send full patch? or just provide me with changelog and I can do it for you thanks, jirka > > > Jan > diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c > index 7a3dbc259cec..400e4832b50e 100644 > --- a/tools/perf/util/unwind-libdw.c > +++ b/tools/perf/util/unwind-libdw.c > @@ -20,10 +20,25 @@ > > static char *debuginfo_path; > > +static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, > + const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, > + const char *file_name __maybe_unused, > + const char *debuglink_file __maybe_unused, > + GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) > +{ > + const struct dso *dso = *userdata; > + > + assert(dso); > + if (dso->symsrc_filename) > + *debuginfo_file_name = strdup(dso->symsrc_filename); > + return -1; > +} > + > static const Dwfl_Callbacks offline_callbacks = { > - .find_debuginfo = dwfl_standard_find_debuginfo, > + .find_debuginfo = __find_debuginfo, > .debuginfo_path = &debuginfo_path, > .section_address = dwfl_offline_section_address, > + // .find_elf is not set as we use dwfl_report_elf() instead. > }; > > static int __report_module(struct addr_location *al, u64 ip, > @@ -46,16 +61,24 @@ static int __report_module(struct addr_location *al, u64 ip, > mod = dwfl_addrmodule(ui->dwfl, ip); > if (mod) { > Dwarf_Addr s; > + void **userdatap; > > - dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); > + dwfl_module_info(mod, &userdatap, &s, NULL, NULL, NULL, NULL, NULL); > + *userdatap = dso; > if (s != al->map->start - al->map->pgoff) > mod = 0; > } > > if (!mod) > - mod = dwfl_report_elf(ui->dwfl, dso->short_name, > - (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff, > - false); > + mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1, > + al->map->start - al->map->pgoff, false); > + if (!mod) { > + char filename[PATH_MAX]; > + > + if (dso__build_id_filename(dso, filename, sizeof(filename), false)) > + mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, > + al->map->start - al->map->pgoff, false); > + } > > return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; > } ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: libdw dwarf unwind issue 2020-12-01 19:41 ` Jiri Olsa @ 2020-12-02 10:06 ` Jan Kratochvil 2020-12-02 10:56 ` Jiri Olsa 0 siblings, 1 reply; 6+ messages in thread From: Jan Kratochvil @ 2020-12-02 10:06 UTC (permalink / raw) To: Jiri Olsa Cc: Frank Ch. Eigler, Mark Wielaard, Arnaldo Carvalho de Melo, Milian Wolff, John Levon, Namhyung Kim, linux-perf-users [-- Attachment #1: Type: text/plain, Size: 282 bytes --] On Tue, 01 Dec 2020 20:41:16 +0100, Jiri Olsa wrote: > the fix is working for me, would you mind send full patch? > or just provide me with changelog and I can do it for you I am not proficient with all the meta-tags there, I make no copyright claims to this patch. Regards, Jan [-- Attachment #2: libdw-unwind3.patch --] [-- Type: text/plain, Size: 2452 bytes --] perf libdw: Fix separte debug info files elfutils needs to be provided main binary and separate debug info file respectively. Providing separate debug info file instead of the main binary is not sufficient. One needs to try both supplied filename and its possible cache by its build-id depending on the use case. diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c index 7a3dbc259cec..0ada907c60d4 100644 --- a/tools/perf/util/unwind-libdw.c +++ b/tools/perf/util/unwind-libdw.c @@ -20,10 +20,24 @@ static char *debuginfo_path; +static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, + const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, + const char *file_name, const char *debuglink_file __maybe_unused, + GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) +{ + const struct dso *dso = *userdata; + + assert(dso); + if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename)) + *debuginfo_file_name = strdup(dso->symsrc_filename); + return -1; +} + static const Dwfl_Callbacks offline_callbacks = { - .find_debuginfo = dwfl_standard_find_debuginfo, + .find_debuginfo = __find_debuginfo, .debuginfo_path = &debuginfo_path, .section_address = dwfl_offline_section_address, + // .find_elf is not set as we use dwfl_report_elf() instead. }; static int __report_module(struct addr_location *al, u64 ip, @@ -46,16 +60,24 @@ static int __report_module(struct addr_location *al, u64 ip, mod = dwfl_addrmodule(ui->dwfl, ip); if (mod) { Dwarf_Addr s; + void **userdatap; - dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); + dwfl_module_info(mod, &userdatap, &s, NULL, NULL, NULL, NULL, NULL); + *userdatap = dso; if (s != al->map->start - al->map->pgoff) mod = 0; } if (!mod) - mod = dwfl_report_elf(ui->dwfl, dso->short_name, - (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff, - false); + mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1, + al->map->start - al->map->pgoff, false); + if (!mod) { + char filename[PATH_MAX]; + + if (dso__build_id_filename(dso, filename, sizeof(filename), false)) + mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, + al->map->start - al->map->pgoff, false); + } return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; } ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: libdw dwarf unwind issue 2020-12-02 10:06 ` Jan Kratochvil @ 2020-12-02 10:56 ` Jiri Olsa 0 siblings, 0 replies; 6+ messages in thread From: Jiri Olsa @ 2020-12-02 10:56 UTC (permalink / raw) To: Jan Kratochvil Cc: Frank Ch. Eigler, Mark Wielaard, Arnaldo Carvalho de Melo, Milian Wolff, John Levon, Namhyung Kim, linux-perf-users On Wed, Dec 02, 2020 at 11:06:46AM +0100, Jan Kratochvil wrote: > On Tue, 01 Dec 2020 20:41:16 +0100, Jiri Olsa wrote: > > the fix is working for me, would you mind send full patch? > > or just provide me with changelog and I can do it for you > > I am not proficient with all the meta-tags there, I make no copyright claims > to this patch. > > > Regards, > Jan > perf libdw: Fix separte debug info files > > elfutils needs to be provided main binary and separate debug info file > respectively. Providing separate debug info file instead of the main binary is > not sufficient. > > One needs to try both supplied filename and its possible cache by its build-id > depending on the use case. it's great, I'll just add your's SOB if that's ok: Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com> thanks, jirka > > diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c > index 7a3dbc259cec..0ada907c60d4 100644 > --- a/tools/perf/util/unwind-libdw.c > +++ b/tools/perf/util/unwind-libdw.c > @@ -20,10 +20,24 @@ > > static char *debuginfo_path; > > +static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, > + const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, > + const char *file_name, const char *debuglink_file __maybe_unused, > + GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) > +{ > + const struct dso *dso = *userdata; > + > + assert(dso); > + if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename)) > + *debuginfo_file_name = strdup(dso->symsrc_filename); > + return -1; > +} > + > static const Dwfl_Callbacks offline_callbacks = { > - .find_debuginfo = dwfl_standard_find_debuginfo, > + .find_debuginfo = __find_debuginfo, > .debuginfo_path = &debuginfo_path, > .section_address = dwfl_offline_section_address, > + // .find_elf is not set as we use dwfl_report_elf() instead. > }; > > static int __report_module(struct addr_location *al, u64 ip, > @@ -46,16 +60,24 @@ static int __report_module(struct addr_location *al, u64 ip, > mod = dwfl_addrmodule(ui->dwfl, ip); > if (mod) { > Dwarf_Addr s; > + void **userdatap; > > - dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); > + dwfl_module_info(mod, &userdatap, &s, NULL, NULL, NULL, NULL, NULL); > + *userdatap = dso; > if (s != al->map->start - al->map->pgoff) > mod = 0; > } > > if (!mod) > - mod = dwfl_report_elf(ui->dwfl, dso->short_name, > - (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff, > - false); > + mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1, > + al->map->start - al->map->pgoff, false); > + if (!mod) { > + char filename[PATH_MAX]; > + > + if (dso__build_id_filename(dso, filename, sizeof(filename), false)) > + mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, > + al->map->start - al->map->pgoff, false); > + } > > return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; > } ^ permalink raw reply [flat|nested] 6+ messages in thread
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[not found] <20201103221709.GL3597846@krava>
2020-11-22 22:27 ` libdw dwarf unwind issue Jan Kratochvil
2020-11-23 22:12 ` Jiri Olsa
2020-11-28 4:07 ` Jan Kratochvil
2020-12-01 19:41 ` Jiri Olsa
2020-12-02 10:06 ` Jan Kratochvil
2020-12-02 10:56 ` Jiri Olsa
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