[PATCH] os: use libunwind to generate backtraces
Peter Hutterer
peter.hutterer at who-t.net
Thu Feb 21 15:02:39 PST 2013
On Thu, Feb 21, 2013 at 08:00:07AM +0100, Marcin Ślusarz wrote:
> 21 lut 2013 00:37, "Peter Hutterer" <peter.hutterer at who-t.net> napisał(a):
> >
> > On Tue, Feb 19, 2013 at 09:29:03PM +0100, Marcin Slusarz wrote:
> > [...]
> > > ---
> > > From: Marcin Slusarz <marcin.slusarz at gmail.com>
> > > Subject: [PATCH] os: use libunwind to generate backtraces
> > >
> > > Libunwind generates backtraces much more reliably than glibc's
> "backtrace".
> > >
> > > Before:
> > > 0: /opt/xserver/bin/X (0x400000+0x18ce36) [0x58ce36]
> > > 1: /opt/xserver/bin/X (xorg_backtrace+0x9) [0x58d119]
> > > 2: /opt/xserver/bin/X (0x400000+0x190d69) [0x590d69]
> > > 3: /lib64/libpthread.so.0 (0x7fb904268000+0x10a90) [0x7fb904278a90]
> > > 4: /lib64/libc.so.6 (ioctl+0x7) [0x7fb902fbf987]
> > > 5: /usr/lib64/libdrm.so.2 (drmIoctl+0x28) [0x7fb90405ffa8]
> > > 6: /usr/lib64/libdrm.so.2 (drmCommandWrite+0x1b) [0x7fb90406235b]
> > > 7: /usr/lib64/libdrm_nouveau.so.2 (nouveau_bo_wait+0x89)
> [0x7fb902009719]
> > > 8: /opt/xserver/lib/xorg/modules/drivers/nouveau_drv.so
> (0x7fb90220e000+0x76f3) [0x7fb9022156f3]
> > > 9: /opt/xserver/lib/xorg/modules/libexa.so (0x7fb9019c7000+0xbae0)
> [0x7fb9019d2ae0]
> > > 10: /opt/xserver/bin/X (0x400000+0x17d2b3) [0x57d2b3]
> > > 11: /opt/xserver/bin/X (0x400000+0xc9930) [0x4c9930]
> > > 12: /opt/xserver/bin/X (0x400000+0x3a81a) [0x43a81a]
> > > 13: /opt/xserver/bin/X (0x400000+0x3d6a1) [0x43d6a1]
> > > 14: /opt/xserver/bin/X (0x400000+0x2c2ca) [0x42c2ca]
> > > 15: /lib64/libc.so.6 (__libc_start_main+0xf5) [0x7fb902f019b5]
> > > 16: /opt/xserver/bin/X (0x400000+0x2c60d) [0x42c60d]
> > > 17: ?? [0x0]
> > >
> > > After:
> > > 0: /opt/xserver/bin/X (OsSigHandler+0x39) [0x590d69]
> > > 1: /lib64/libpthread.so.0 (__restore_rt+0x0) [0x7fb904278a8f]
> > > 2: /lib64/libc.so.6 (ioctl+0x7) [0x7fb902fbf987]
> > > 3: /usr/lib64/libdrm.so.2 (drmIoctl+0x28) [0x7fb90405ffa8]
> > > 4: /usr/lib64/libdrm.so.2 (drmCommandWrite+0x1b) [0x7fb90406235b]
> > > 5: /usr/lib64/libdrm_nouveau.so.2 (nouveau_bo_wait+0x89)
> [0x7fb902009719]
> > > 6: /opt/xserver/lib/xorg/modules/drivers/nouveau_drv.so
> (nouveau_exa_download_from_screen+0x1a3) [0x7fb9022156f3]
> > > 7: /opt/xserver/lib/xorg/modules/libexa.so (exaGetImage+0x1f0)
> [0x7fb9019d2ae0]
> > > 8: /opt/xserver/bin/X (miSpriteGetImage+0x173) [0x57d2b3]
> > > 9: /opt/xserver/bin/X (compGetImage+0xb0) [0x4c9930]
> > > 10: /opt/xserver/bin/X (ProcGetImage+0x55a) [0x43a81a]
> > > 11: /opt/xserver/bin/X (Dispatch+0x341) [0x43d6a1]
> > > 12: /opt/xserver/bin/X (main+0x3ba) [0x42c2ca]
> > > 13: /lib64/libc.so.6 (__libc_start_main+0xf5) [0x7fb902f019b5]
> > > 14: /opt/xserver/bin/X (_start+0x29) [0x42c60d]
> > > 15: ? (?+0x29) [0x29]
> > >
> > > Signed-off-by: Marcin Slusarz <marcin.slusarz at gmail.com>
> > > ---
> > > configure.ac | 7 +++++
> > > include/dix-config.h.in | 3 ++
> > > os/Makefile.am | 5 ++++
> > > os/backtrace.c | 75
> +++++++++++++++++++++++++++++++++++++++++++++++++
> > > 4 files changed, 90 insertions(+)
> > >
> > > diff --git a/configure.ac b/configure.ac
> > > index 9415a54..4a292da 100644
> > > --- a/configure.ac
> > > +++ b/configure.ac
> > > @@ -309,6 +309,13 @@ AC_CHECK_HEADER([execinfo.h],[
> > > ])]
> > > )
> > >
> > > +PKG_CHECK_MODULES(LIBUNWIND, libunwind, [HAVE_LIBUNWIND=yes],
> [HAVE_LIBUNWIND=no])
> > > +if test "x$HAVE_LIBUNWIND" = xyes; then
> > > + AC_DEFINE(HAVE_LIBUNWIND, 1, [Have libunwind support])
> > > +fi
> > > +AM_CONDITIONAL(HAVE_LIBUNWIND, [test "x$HAVE_LIBUNWIND" = xyes])
> > > +
> > > +
> > > dnl
> ---------------------------------------------------------------------------
> > > dnl Bus options and CPU capabilities. Replaces logic in
> > > dnl hw/xfree86/os-support/bus/Makefile.am, among others.
> > > diff --git a/include/dix-config.h.in b/include/dix-config.h.in
> > > index 578f249..5102263 100644
> > > --- a/include/dix-config.h.in
> > > +++ b/include/dix-config.h.in
> > > @@ -60,6 +60,9 @@
> > > /* Has backtrace support */
> > > #undef HAVE_BACKTRACE
> > >
> > > +/* Has libunwind support */
> > > +#undef HAVE_LIBUNWIND
> > > +
> > > /* Define to 1 if you have the <byteswap.h> header file. */
> > > #undef HAVE_BYTESWAP_H
> > >
> > > diff --git a/os/Makefile.am b/os/Makefile.am
> > > index 8891485..364b6da 100644
> > > --- a/os/Makefile.am
> > > +++ b/os/Makefile.am
> > > @@ -34,6 +34,11 @@ if XDMCP
> > > libos_la_SOURCES += $(XDMCP_SRCS)
> > > endif
> > >
> > > +if HAVE_LIBUNWIND
> > > +AM_CFLAGS += $(LIBUNWIND_CFLAGS)
> > > +libos_la_LIBADD += $(LIBUNWIND_LIBS)
> > > +endif
> > > +
> > > EXTRA_DIST = $(SECURERPC_SRCS) $(XDMCP_SRCS)
> > >
> > > if SPECIAL_DTRACE_OBJECTS
> > > diff --git a/os/backtrace.c b/os/backtrace.c
> > > index daac60c..426f9b1 100644
> > > --- a/os/backtrace.c
> > > +++ b/os/backtrace.c
> > > @@ -30,6 +30,80 @@
> > > #include <errno.h>
> > > #include <string.h>
> > >
> > > +#ifdef HAVE_LIBUNWIND
> > > +
> > > +#define UNW_LOCAL_ONLY
> > > +#include <libunwind.h>
> > > +
> > > +#ifndef _GNU_SOURCE
> > > +#define _GNU_SOURCE
> > > +#endif
> > > +#include <dlfcn.h>
> > > +
> > > +void
> > > +xorg_backtrace(void)
> > > +{
> > > + unw_cursor_t cursor;
> > > + unw_context_t context;
> > > + unw_word_t off;
> > > + unw_proc_info_t pip;
> > > + int ret, i = 0;
> > > + char procname[256];
> > > + const char *filename;
> > > + Dl_info dlinfo;
> > > +
> > > + pip.unwind_info = NULL;
> > > + ret = unw_getcontext(&context);
> > > + if (ret) {
> > > + ErrorFSigSafe("unw_getcontext failed: %s [%d]\n",
> unw_strerror(ret),
> > > + ret);
> > > + return;
> > > + }
> > > +
> > > + ret = unw_init_local(&cursor, &context);
> > > + if (ret) {
> > > + ErrorFSigSafe("unw_init_local failed: %s [%d]\n",
> unw_strerror(ret),
> > > + ret);
> > > + return;
> > > + }
> > > +
> > > + ErrorFSigSafe("\n");
> > > + ErrorFSigSafe("Backtrace:\n");
> > > + ret = unw_step(&cursor);
> > > + while (ret > 0) {
> > > + ret = unw_get_proc_info(&cursor, &pip);
> > > + if (ret) {
> > > + ErrorFSigSafe("unw_get_proc_info failed: %s [%d]\n",
> > > + unw_strerror(ret), ret);
> > > + break;
> > > + }
> > > +
> > > + ret = unw_get_proc_name(&cursor, procname, 256, &off);
> > > + if (ret && ret != -UNW_ENOMEM) {
> > > + if (ret != -UNW_EUNSPEC)
> > > + ErrorFSigSafe("unw_get_proc_name failed: %s [%d]\n",
> > > + unw_strerror(ret), ret);
> > > + procname[0] = '?';
> > > + procname[1] = 0;
> > > + }
> > > +
> > > + if (dladdr((void *)(pip.start_ip + off), &dlinfo) &&
> dlinfo.dli_fname &&
> > > + *dlinfo.dli_fname)
> > > + filename = dlinfo.dli_fname;
> > > + else
> > > + filename = "?";
> > > +
> > > + ErrorFSigSafe("%u: %s (%s%s+0x%x) [%p]\n", i++, filename,
> procname,
> > > + ret == -UNW_ENOMEM ? "..." : "", (int)off,
> > > + (void *)(pip.start_ip + off));
> > > +
> > > + ret = unw_step(&cursor);
> > > + if (ret < 0)
> > > + ErrorFSigSafe("unw_step failed: %s [%d]\n",
> unw_strerror(ret), ret);
> > > + }
> > > + ErrorFSigSafe("\n");
> > > +}
> > > +#else /* HAVE_LIBUNWIND */
> > > #ifdef HAVE_BACKTRACE
> > > #ifndef _GNU_SOURCE
> > > #define _GNU_SOURCE
> > > @@ -246,3 +320,4 @@ xorg_backtrace(void)
> > >
> > > #endif
> > > #endif
> > > +#endif
> > > --
> > > 1.8.1
> >
> > thanks for the changes but after applying this patch locally I do wonder:
> > how did you test this? i'm getting undefined references to the various
> > libunwind calls (_Ux86_64_getcontext, _Ux86_64_strerror,etc) for Xvfb,
> Xdmx, Xnext
> > and all the tests). This needs some more polishing.
>
> Try to do make clean before building.
> For some reason libos.la is not updated automatically.
I did to a make distclean and it still won't work. did a fresh clone, and
I'm still getting
CCLD Xvfb
../../os/os.O: In function `xorg_backtrace':
/home/whot/xorg/xserver/os/backtrace.c:56: undefined reference to
`_Ux86_64_getcontext'
/home/whot/xorg/xserver/os/backtrace.c:58: undefined reference to
`_Ux86_64_strerror'
/home/whot/xorg/xserver/os/backtrace.c:63: undefined reference to
`_ULx86_64_init_local'
/home/whot/xorg/xserver/os/backtrace.c:65: undefined reference to
`_Ux86_64_strerror'
/home/whot/xorg/xserver/os/backtrace.c:72: undefined reference to
`_ULx86_64_step'
/home/whot/xorg/xserver/os/backtrace.c:74: undefined reference to
`_ULx86_64_get_proc_info'
/home/whot/xorg/xserver/os/backtrace.c:76: undefined reference to
`_Ux86_64_strerror'
/home/whot/xorg/xserver/os/backtrace.c:81: undefined reference to
`_ULx86_64_get_proc_name'
/home/whot/xorg/xserver/os/backtrace.c:84: undefined reference to
`_Ux86_64_strerror'
/home/whot/xorg/xserver/os/backtrace.c:100: undefined reference to
`_ULx86_64_step'
/home/whot/xorg/xserver/os/backtrace.c:102: undefined reference to
`_Ux86_64_strerror'
if you look at the hw/xfree86/Makefile.am, libos.la is uses twice, once from
XSERVER_LIBS, once at the end again. This isn't the case for the other
DDX's, I suspect this may be the reason.
Cheers,
Peter
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