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(-)
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@GLIBC_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@google.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 45d3d8b3317a..80375ca39a37 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>
@@ -231,6 +234,16 @@ 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);
}
@@ -244,7 +257,7 @@ 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);
--
2.50.0.rc1.591.g9c95f17f64-googOn Wed, Jun 11, 2025 at 03:15:21PM -0700, Ian Rogers wrote:
> 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@GLIBC_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@google.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 45d3d8b3317a..80375ca39a37 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>
> @@ -231,6 +234,16 @@ 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);
> }
>
> @@ -244,7 +257,7 @@ 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))
It seems addr_location__exit(&al) is needed here.
Thanks,
Namhyung
> + 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);
>
> --
> 2.50.0.rc1.591.g9c95f17f64-goog
>
On Fri, Jun 20, 2025 at 1:23 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Wed, Jun 11, 2025 at 03:15:21PM -0700, Ian Rogers wrote:
> > 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@GLIBC_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@google.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 45d3d8b3317a..80375ca39a37 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>
> > @@ -231,6 +234,16 @@ 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);
> > }
> >
> > @@ -244,7 +257,7 @@ 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))
>
> It seems addr_location__exit(&al) is needed here.
Good catch. I don't think it changes the behavior of the code but is
cleaner. I'll fix in v4.
Thanks,
Ian
> Thanks,
> Namhyung
>
>
> > + 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);
> >
> > --
> > 2.50.0.rc1.591.g9c95f17f64-goog
> >
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