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.:
Jiri, can you review this one? 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 <[email protected]> > Cc: Namhyung Kim <[email protected]> > Cc: Jiri Olsa <[email protected]> > Signed-off-by: Milian Wolff <[email protected]> > --- > 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
