compositor: Use libunwind if available for better backtraces
libunwind has a dwarf parser and automatically queries the dlinfo
for location of dlopened modules. The resulting backtrace is much
better and includes stack frames in dynamically loaded modules.
krh: Originally submitted for Xorg, adapted for weston:
http://lists.x.org/archives/xorg-devel/2013-February/035493.html
Note this require libunwind at least 1.1 to get the pkg-config files.
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
diff --git a/src/compositor.c b/src/compositor.c
index 63fe793..5c19d92 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -49,6 +49,11 @@
#include <sys/time.h>
#include <time.h>
+#ifdef HAVE_LIBUNWIND
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+#endif
+
#include <wayland-server.h>
#include "compositor.h"
#include "../shared/os-compatibility.h"
@@ -3051,13 +3056,88 @@
return 1;
}
+#ifdef HAVE_LIBUNWIND
+
static void
-on_segv_signal(int s, siginfo_t *siginfo, void *context)
+print_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) {
+ weston_log("unw_getcontext: %d\n", ret);
+ return;
+ }
+
+ ret = unw_init_local(&cursor, &context);
+ if (ret) {
+ weston_log("unw_init_local: %d\n", ret);
+ return;
+ }
+
+ ret = unw_step(&cursor);
+ while (ret > 0) {
+ ret = unw_get_proc_info(&cursor, &pip);
+ if (ret) {
+ weston_log("unw_get_proc_info: %d\n", ret);
+ break;
+ }
+
+ ret = unw_get_proc_name(&cursor, procname, 256, &off);
+ if (ret && ret != -UNW_ENOMEM) {
+ if (ret != -UNW_EUNSPEC)
+ weston_log("unw_get_proc_name: %d\n", 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 = "?";
+
+ weston_log("%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)
+ weston_log("unw_step: %d\n", ret);
+ }
+}
+
+#else
+
+static void
+print_backtrace(void)
{
void *buffer[32];
int i, count;
Dl_info info;
+ count = backtrace(buffer, ARRAY_LENGTH(buffer));
+ for (i = 0; i < count; i++) {
+ dladdr(buffer[i], &info);
+ weston_log(" [%016lx] %s (%s)\n",
+ (long) buffer[i],
+ info.dli_sname ? info.dli_sname : "--",
+ info.dli_fname);
+ }
+}
+
+#endif
+
+static void
+on_segv_signal(int s, siginfo_t *siginfo, void *context)
+{
/* This SIGSEGV handler will do a best-effort backtrace, and
* then call the backend restore function, which will switch
* back to the vt we launched from or ungrab X etc and then
@@ -3068,14 +3148,7 @@
weston_log("caught segv\n");
- count = backtrace(buffer, ARRAY_LENGTH(buffer));
- for (i = 0; i < count; i++) {
- dladdr(buffer[i], &info);
- weston_log(" [%016lx] %s (%s)\n",
- (long) buffer[i],
- info.dli_sname ? info.dli_sname : "--",
- info.dli_fname);
- }
+ print_backtrace();
segv_compositor->restore(segv_compositor);