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Message-Id: <20250313052952.871958-2-irogers@google.com>
Date: Wed, 12 Mar 2025 22:29:52 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>, James Clark <james.clark@...aro.org>,
Yicong Yang <yangyicong@...ilicon.com>, Howard Chu <howardchu95@...il.com>,
Andi Kleen <ak@...ux.intel.com>, Michael Petlan <mpetlan@...hat.com>,
Anne Macedo <retpolanne@...teo.net>, "Dr. David Alan Gilbert" <linux@...blig.org>,
Dmitry Vyukov <dvyukov@...gle.com>, linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v1 2/2] perf debug: Add function symbols to dump_stack
Symbolize stack traces by creating a live machine. Add this
functionality to dump_stack and switch dump_stack users to use
it. Switch TUI to use it. Add stack traces to the child test function
which can be useful to diagnose blocked code.
Example output:
```
8: PERF_RECORD_* events & perf_sample fields : Running (1 active)
^C
Signal (2) while running tests.
Terminating tests with the same signal
Internal test harness failure. Completing any started tests:
: 8: PERF_RECORD_* events & perf_sample fields:
---- unexpected signal (2) ----
#0 0x5590fb6209b6 in child_test_sig_handler builtin-test.c:243
#1 0x7f4a91e49e20 in __restore_rt libc_sigaction.c:0
#2 0x7f4a91ee4f33 in clock_nanosleep@...BC_2.2.5 clock_nanosleep.c:71
#3 0x7f4a91ef0333 in __nanosleep nanosleep.c:26
#4 0x7f4a91f01f68 in __sleep sleep.c:55
#5 0x5590fb638c63 in test__PERF_RECORD perf-record.c:295
#6 0x5590fb620b43 in run_test_child builtin-test.c:269
#7 0x5590fb5b83ab in start_command run-command.c:127
#8 0x5590fb621572 in start_test builtin-test.c:467
#9 0x5590fb621a47 in __cmd_test builtin-test.c:573
#10 0x5590fb6225ea in cmd_test builtin-test.c:775
#11 0x5590fb5a9099 in run_builtin perf.c:351
#12 0x5590fb5a9340 in handle_internal_command perf.c:404
#13 0x5590fb5a9499 in run_argv perf.c:451
#14 0x5590fb5a97e2 in main perf.c:558
#15 0x7f4a91e33d68 in __libc_start_call_main libc_start_call_main.h:74
#16 0x7f4a91e33e25 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
#17 0x5590fb4fd6d1 in _start perf[436d1]
```
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
tools/perf/tests/builtin-test.c | 15 +++++++-
tools/perf/ui/tui/setup.c | 2 +-
tools/perf/util/debug.c | 64 +++++++++++++++++++++++++++------
tools/perf/util/debug.h | 1 +
4 files changed, 69 insertions(+), 13 deletions(-)
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 14d30a5053be..358bccc75d40 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -6,6 +6,9 @@
*/
#include <fcntl.h>
#include <errno.h>
+#ifdef HAVE_BACKTRACE_SUPPORT
+#include <execinfo.h>
+#endif
#include <poll.h>
#include <unistd.h>
#include <setjmp.h>
@@ -230,6 +233,16 @@ static jmp_buf run_test_jmp_buf;
static void child_test_sig_handler(int sig)
{
+#ifdef HAVE_BACKTRACE_SUPPORT
+ void *stackdump[32];
+ size_t stackdump_size;
+#endif
+
+ fprintf(stderr, "\n---- unexpected signal (%d) ----\n", sig);
+#ifdef HAVE_BACKTRACE_SUPPORT
+ stackdump_size = backtrace(stackdump, ARRAY_SIZE(stackdump));
+ __dump_stack(stderr, stackdump, stackdump_size);
+#endif
siglongjmp(run_test_jmp_buf, sig);
}
@@ -243,7 +256,7 @@ static int run_test_child(struct child_process *process)
err = sigsetjmp(run_test_jmp_buf, 1);
if (err) {
- fprintf(stderr, "\n---- unexpected signal (%d) ----\n", err);
+ /* Received signal. */
err = err > 0 ? -err : -1;
goto err_out;
}
diff --git a/tools/perf/ui/tui/setup.c b/tools/perf/ui/tui/setup.c
index 16c6eff4d241..022534eed68c 100644
--- a/tools/perf/ui/tui/setup.c
+++ b/tools/perf/ui/tui/setup.c
@@ -108,7 +108,7 @@ static void ui__signal_backtrace(int sig)
printf("-------- backtrace --------\n");
size = backtrace(stackdump, ARRAY_SIZE(stackdump));
- backtrace_symbols_fd(stackdump, size, STDOUT_FILENO);
+ __dump_stack(stdout, stackdump, size);
exit(0);
}
diff --git a/tools/perf/util/debug.c b/tools/perf/util/debug.c
index f9ef7d045c92..8987ac250079 100644
--- a/tools/perf/util/debug.c
+++ b/tools/perf/util/debug.c
@@ -14,11 +14,18 @@
#ifdef HAVE_BACKTRACE_SUPPORT
#include <execinfo.h>
#endif
+#include "addr_location.h"
#include "color.h"
-#include "event.h"
#include "debug.h"
+#include "event.h"
+#include "machine.h"
+#include "map.h"
#include "print_binary.h"
+#include "srcline.h"
+#include "symbol.h"
+#include "synthetic-events.h"
#include "target.h"
+#include "thread.h"
#include "trace-event.h"
#include "ui/helpline.h"
#include "ui/ui.h"
@@ -298,21 +305,56 @@ void perf_debug_setup(void)
libapi_set_print(pr_warning_wrapper, pr_warning_wrapper, pr_debug_wrapper);
}
+void __dump_stack(FILE *file, void **stackdump, size_t stackdump_size)
+{
+ /* TODO: async safety. printf, malloc, etc. aren't safe inside a signal handler. */
+ pid_t pid = getpid();
+ struct machine *machine = machine__new_live(/*kernel_maps=*/false, pid);
+ struct thread *thread = NULL;
+
+ if (machine)
+ thread = machine__find_thread(machine, pid, pid);
+
+ if (!machine || !thread) {
+ /*
+ * Backtrace functions are async signal safe. Fall back on them
+ * if machine/thread creation fails.
+ */
+ backtrace_symbols_fd(stackdump, stackdump_size, fileno(file));
+ machine__delete(machine);
+ return;
+ }
+
+ for (size_t i = 0; i < stackdump_size; i++) {
+ struct addr_location al;
+ u64 addr = (u64)stackdump[i];
+
+ addr_location__init(&al);
+ if (!thread__find_map(thread, PERF_RECORD_MISC_USER, addr, &al))
+ continue;
+
+ al.sym = map__find_symbol(al.map, al.addr);
+ if (al.sym)
+ fprintf(file, " #%zd %p in %s ", i, stackdump[i], al.sym->name);
+ else
+ fprintf(file, " #%zd %p ", i, stackdump[i]);
+
+ map__fprintf_srcline(al.map, al.addr, "", file);
+ fprintf(file, "\n");
+ addr_location__exit(&al);
+ }
+ thread__put(thread);
+ machine__delete(machine);
+}
+
/* Obtain a backtrace and print it to stdout. */
#ifdef HAVE_BACKTRACE_SUPPORT
void dump_stack(void)
{
- void *array[16];
- size_t size = backtrace(array, ARRAY_SIZE(array));
- char **strings = backtrace_symbols(array, size);
- size_t i;
-
- printf("Obtained %zd stack frames.\n", size);
-
- for (i = 0; i < size; i++)
- printf("%s\n", strings[i]);
+ void *stackdump[32];
+ size_t size = backtrace(stackdump, ARRAY_SIZE(stackdump));
- free(strings);
+ __dump_stack(stdout, stackdump, size);
}
#else
void dump_stack(void) {}
diff --git a/tools/perf/util/debug.h b/tools/perf/util/debug.h
index a4026d1fd6a3..6b737e195ce1 100644
--- a/tools/perf/util/debug.h
+++ b/tools/perf/util/debug.h
@@ -85,6 +85,7 @@ void debug_set_display_time(bool set);
void perf_debug_setup(void);
int perf_quiet_option(void);
+void __dump_stack(FILE *file, void **stackdump, size_t stackdump_size);
void dump_stack(void);
void sighandler_dump_stack(int sig);
--
2.49.0.rc0.332.g42c0ae87b1-goog
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