[PATCH v2] perf tools: Introduce perf_thread for backtrace
From: Namhyung Kim
Date: Wed Dec 02 2015 - 00:42:56 EST
Backtrace is a crucial info for debugging. And upcoming refcnt
tracking facility also wants to use it.
So instead of relying on glibc's backtrace_symbols[_fd] which misses
some (static) functions , use our own symbol searching mechanism. To
do that, add perf_thread global variable to keep its maps and symbols.
The backtrace output from TUI is changed like below. (I made a key
action to generate a segfault):
Before:
perf: Segmentation fault
-------- backtrace --------
perf[0x544a8b]
/usr/lib/libc.so.6(+0x33680)[0x7fc46420b680]
perf[0x54041b]
perf(perf_evlist__tui_browse_hists+0x91)[0x5432e1]
perf(cmd_report+0x1d20)[0x43cb10]
perf[0x487073]
perf(main+0x62f)[0x42cb1f]
/usr/lib/libc.so.6(__libc_start_main+0xf0)[0x7fc4641f8610]
perf(_start+0x29)[0x42cc39]
After:
perf: Segmentation fault
-------- backtrace --------
perf_evsel__hists_browse(+0x43b) in perf [0x54066b]
perf_evlist__tui_browse_hists(+0x91) in perf [0x543531]
cmd_report(+0x1d20) in perf [0x43cb50]
run_builtin(+0x53) in perf [0x4870b3]
main(+0x634) in perf [0x42cb54]
__libc_start_main(+0xf0) in libc-2.22.so [0x7fea3577c610]
_start(+0x29) in perf [0x42cc79]
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
v2) fallback to glibc's backtrace_symbols_fd() if failed
tools/perf/perf.c | 7 +++++-
tools/perf/ui/tui/setup.c | 31 ++++++++++++++++++++++--
tools/perf/util/util.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/util.h | 5 ++++
4 files changed, 102 insertions(+), 3 deletions(-)
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 4bee53c3f796..f77eb440b05c 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -604,6 +604,8 @@ int main(int argc, const char **argv)
*/
pthread__block_sigwinch();
+ create_perf_thread();
+
while (1) {
static int done_help;
int was_alias = run_argv(&argc, &argv);
@@ -615,7 +617,7 @@ int main(int argc, const char **argv)
fprintf(stderr, "Expansion of alias '%s' failed; "
"'%s' is not a perf-command\n",
cmd, argv[0]);
- goto out;
+ goto out_destroy;
}
if (!done_help) {
cmd = argv[0] = help_unknown_cmd(cmd);
@@ -626,6 +628,9 @@ int main(int argc, const char **argv)
fprintf(stderr, "Failed to run command '%s': %s\n",
cmd, strerror_r(errno, sbuf, sizeof(sbuf)));
+
+out_destroy:
+ destroy_perf_thread();
out:
return 1;
}
diff --git a/tools/perf/ui/tui/setup.c b/tools/perf/ui/tui/setup.c
index 7dfeba0a91f3..ba0ff1c4e6b7 100644
--- a/tools/perf/ui/tui/setup.c
+++ b/tools/perf/ui/tui/setup.c
@@ -13,6 +13,8 @@
#include "../libslang.h"
#include "../keysyms.h"
#include "tui.h"
+#include "../../util/symbol.h"
+#include "../../util/thread.h"
static volatile int ui__need_resize;
@@ -96,14 +98,39 @@ int ui__getch(int delay_secs)
static void ui__signal_backtrace(int sig)
{
void *stackdump[32];
- size_t size;
+ size_t size, i;
ui__exit(false);
psignal(sig, "perf");
printf("-------- backtrace --------\n");
size = backtrace(stackdump, ARRAY_SIZE(stackdump));
- backtrace_symbols_fd(stackdump, size, STDOUT_FILENO);
+ /* skip first two stack frame (for this function and signal stack) */
+ for (i = 2; i < size; i++) {
+ struct addr_location al = {
+ .sym = NULL,
+ };
+
+ /* valid callchain ends with 0 address */
+ if (stackdump[i] == NULL && i == (size - 1))
+ continue;
+
+ thread__find_addr_location(perf_thread, PERF_RECORD_MISC_USER,
+ MAP__FUNCTION, (long)stackdump[i], &al);
+
+ if (!al.sym)
+ break;
+
+ printf("%s(+0x%"PRIx64") in %s [0x%lx]\n", al.sym->name,
+ map__map_ip(al.map, (u64)stackdump[i]) - al.sym->start,
+ al.map->dso->short_name, (unsigned long)stackdump[i]);
+ }
+
+ if (i != size) {
+ printf("\nperf backtrace seems broken, try again with glibc\n");
+ printf("-------- backtrace --------\n");
+ backtrace_symbols_fd(stackdump, size, STDOUT_FILENO);
+ }
exit(0);
}
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 75759aebc7b8..f1a26ea14053 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -16,6 +16,9 @@
#include <linux/kernel.h>
#include <unistd.h>
#include "callchain.h"
+#include "machine.h"
+#include "thread.h"
+#include "thread_map.h"
struct callchain_param callchain_param = {
.mode = CHAIN_GRAPH_ABS,
@@ -696,3 +699,62 @@ fetch_kernel_version(unsigned int *puint, char *str,
*puint = (version << 16) + (patchlevel << 8) + sublevel;
return 0;
}
+
+
+static int process_event(struct perf_tool *tool, union perf_event *event,
+ struct perf_sample *sample, struct machine *machine)
+{
+ switch (event->header.type) {
+ case PERF_RECORD_COMM:
+ return tool->comm(tool, event, sample, machine);
+ case PERF_RECORD_MMAP:
+ return tool->mmap(tool, event, sample, machine);
+ case PERF_RECORD_MMAP2:
+ return tool->mmap2(tool, event, sample, machine);
+ default:
+ break;
+ }
+ return 0;
+}
+
+struct thread *perf_thread;
+
+void create_perf_thread(void)
+{
+ struct perf_tool tool = {
+ .comm = perf_event__process_comm,
+ .mmap = perf_event__process_mmap,
+ .mmap2 = perf_event__process_mmap2,
+ };
+ struct thread_map *tm;
+ struct machine *machine;
+ int pid = getpid();
+
+ machine = machine__new_host();
+ if (machine == NULL)
+ return;
+
+ tm = thread_map__new_dummy();
+ if (tm == NULL) {
+ machine__delete(machine);
+ return;
+ }
+
+ thread_map__set_pid(tm, 0, pid);
+
+ perf_event__synthesize_thread_map(&tool, tm, process_event, machine,
+ false, 500);
+
+ perf_thread = machine__find_thread(machine, pid, pid);
+ BUG_ON(perf_thread == NULL);
+
+ thread_map__put(tm);
+}
+
+void destroy_perf_thread(void)
+{
+ struct machine *machine = perf_thread->mg->machine;
+
+ machine__delete_threads(machine);
+ machine__delete(machine);
+}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index dcc659017976..630e145049aa 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -358,4 +358,9 @@ int fetch_kernel_version(unsigned int *puint,
#define KVER_FMT "%d.%d.%d"
#define KVER_PARAM(x) KVER_VERSION(x), KVER_PATCHLEVEL(x), KVER_SUBLEVEL(x)
+extern struct thread *perf_thread;
+
+void create_perf_thread(void);
+void destroy_perf_thread(void);
+
#endif /* GIT_COMPAT_UTIL_H */
--
2.6.2
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