Messages in this thread | | | Date | Mon, 5 Jun 2017 12:47:20 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH 2/2] perf report: report module before querying isactivation in dwfl unwind |
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On Fri, Jun 02, 2017 at 12:25:08PM -0300, Arnaldo Carvalho de Melo wrote: > Em Fri, Jun 02, 2017 at 04:37:53PM +0200, Milian Wolff escreveu: > > The PC returned by dwfl_frame_pc may map into a not-yet-reported > > module. We have to report it before we continue unwinding. But when > > we query for the isactivation flag in dwfl_frame_pc, libdw will > > actually do one more unwinding step internally which can then break > > and lead to missed frames or broken stacks. > > > > With libunwind we get e.g.:
sounds like a libdw design issue.. Jan is there a specific way to handle the case that Milian described?
thanks, jirka
> > Thanks, > > - Arnaldo > > > ~~~~~ > > heaptrack_gui 2228 135073.400474: 613969 cycles: > > 108c8e [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 1093bc [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 109e7b QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0) > > 1470ff [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 147f67 QSystemLocale::query (/usr/lib/libQt5Core.so.5.8.0) > > 109fbf QLocalePrivate::updateSystemPrivate (/usr/lib/libQt5Core.so.5.8.0) > > 10aa27 QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0) > > 1e02c3 [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 2113bb [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 211505 [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 1b5df0 QFileInfo::exists (/usr/lib/libQt5Core.so.5.8.0) > > 92eb2 [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 93423 [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 93d2a QLibraryInfo::location (/usr/lib/libQt5Core.so.5.8.0) > > 2170af [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 297c53 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0) > > f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0) > > 1589e8 QApplicationPrivate::init (/usr/lib/libQt5Widgets.so.5.8.0) > > 78622 main (/home/milian/projects/compiled/other/bin/heaptrack_gui) > > 20439 __libc_start_main (/usr/lib/libc-2.25.so) > > 78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui) > > > > heaptrack_gui 2228 135073.401156: 569521 cycles: > > 131633 QString::endsWith (/usr/lib/libQt5Core.so.5.8.0) > > 1a0701 QDir::cleanPath (/usr/lib/libQt5Core.so.5.8.0) > > 21b82d [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 1b3727 QFileInfo::canonicalFilePath (/usr/lib/libQt5Core.so.5.8.0) > > 2780c7 QFactoryLoader::update (/usr/lib/libQt5Core.so.5.8.0) > > 279525 QFactoryLoader::QFactoryLoader (/usr/lib/libQt5Core.so.5.8.0) > > e5bd0 QPlatformIntegrationFactory::create (/usr/lib/libQt5Gui.so.5.8.0) > > f5a1c QGuiApplicationPrivate::createPlatformIntegration (/usr/lib/libQt5Gui.so.5.8.0) > > f650c QGuiApplicationPrivate::createEventDispatcher (/usr/lib/libQt5Gui.so.5.8.0) > > 298524 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0) > > f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0) > > 1589e8 QApplicationPrivate::init (/usr/lib/libQt5Widgets.so.5.8.0) > > 78622 main (/home/milian/projects/compiled/other/bin/heaptrack_gui) > > 20439 __libc_start_main (/usr/lib/libc-2.25.so) > > 78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui) > > ~~~~~ > > > > Note the two frames 1589e8 and 78622 in the first sample. These are > > missing when unwinding with libdw. The second sample's breakage is > > more obvious: > > > > ~~~~~ > > heaptrack_gui 2228 135073.400474: 613969 cycles: > > 108c8e [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 1093bc [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 109e7b QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0) > > 1470ff [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 147f67 QSystemLocale::query (/usr/lib/libQt5Core.so.5.8.0) > > 109fbf QLocalePrivate::updateSystemPrivate (/usr/lib/libQt5Core.so.5.8.0) > > 10aa27 QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0) > > 1e02c3 [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 2113bb [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 211505 [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 1b5df0 QFileInfo::exists (/usr/lib/libQt5Core.so.5.8.0) > > 92eb2 [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 93423 [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 93d2a QLibraryInfo::location (/usr/lib/libQt5Core.so.5.8.0) > > 2170af [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 297c53 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0) > > f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0) > > 20439 __libc_start_main (/usr/lib/libc-2.25.so) > > 78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui) > > > > heaptrack_gui 2228 135073.401156: 569521 cycles: > > 131633 QString::endsWith (/usr/lib/libQt5Core.so.5.8.0) > > 1a0701 QDir::cleanPath (/usr/lib/libQt5Core.so.5.8.0) > > 21b82d [unknown] (/usr/lib/libQt5Core.so.5.8.0) > > 1b3727 QFileInfo::canonicalFilePath (/usr/lib/libQt5Core.so.5.8.0) > > 2780c7 QFactoryLoader::update (/usr/lib/libQt5Core.so.5.8.0) > > 279525 QFactoryLoader::QFactoryLoader (/usr/lib/libQt5Core.so.5.8.0) > > e5bd0 QPlatformIntegrationFactory::create (/usr/lib/libQt5Gui.so.5.8.0) > > 723dbf [unknown] ([unknown]) > > ~~~~~ > > > > This patch fixes this issue and the libdw unwinder mimicks the > > libunwind behavior more closely. > > > > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > > Cc: Namhyung Kim <namhyung@kernel.org> > > Cc: Jiri Olsa <jolsa@redhat.com> > > Signed-off-by: Milian Wolff <milian.wolff@kdab.com> > > --- > > tools/perf/util/unwind-libdw.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c > > index da45c4be5fb3..7755a5e0fe5e 100644 > > --- a/tools/perf/util/unwind-libdw.c > > +++ b/tools/perf/util/unwind-libdw.c > > @@ -178,6 +178,14 @@ frame_callback(Dwfl_Frame *state, void *arg) > > Dwarf_Addr pc; > > bool isactivation; > > > > + if (!dwfl_frame_pc(state, &pc, NULL)) { > > + pr_err("%s", dwfl_errmsg(-1)); > > + return DWARF_CB_ABORT; > > + } > > + > > + // report the module before we query for isactivation > > + report_module(pc, ui); > > + > > if (!dwfl_frame_pc(state, &pc, &isactivation)) { > > pr_err("%s", dwfl_errmsg(-1)); > > return DWARF_CB_ABORT; > > -- > > 2.13.0
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