Commit 9c9f4a27 authored by Ian Rogers's avatar Ian Rogers Committed by Namhyung Kim
Browse files

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:
```
$ perf test -vv PERF_RECORD_
...
  7: PERF_RECORD_* events & perf_sample fields:
  7: 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:
:  7: PERF_RECORD_* events & perf_sample fields:

---- unexpected signal (2) ----
    #0 0x55788c6210a3 in child_test_sig_handler builtin-test.c:0
    #1 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
    #2 0x7fc12fe99687 in __internal_syscall_cancel cancellation.c:64
    #3 0x7fc12fee5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72
    #4 0x7fc12fef1393 in __nanosleep nanosleep.c:26
    #5 0x7fc12ff02d68 in __sleep sleep.c:55
    #6 0x55788c63196b in test__PERF_RECORD perf-record.c:0
    #7 0x55788c620fb0 in run_test_child builtin-test.c:0
    #8 0x55788c5bd18d in start_command run-command.c:127
    #9 0x55788c621ef3 in __cmd_test builtin-test.c:0
    #10 0x55788c6225bf in cmd_test ??:0
    #11 0x55788c5afbd0 in run_builtin perf.c:0
    #12 0x55788c5afeeb in handle_internal_command perf.c:0
    #13 0x55788c52b383 in main ??:0
    #14 0x7fc12fe33ca8 in __libc_start_call_main libc_start_call_main.h:74
    #15 0x7fc12fe33d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
    #16 0x55788c52b9d1 in _start ??:0

---- unexpected signal (2) ----
    #0 0x55788c6210a3 in child_test_sig_handler builtin-test.c:0
    #1 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
    #2 0x7fc12fea3a14 in pthread_sigmask@GLIBC_2.2.5 pthread_sigmask.c:45
    #3 0x7fc12fe49fd9 in __GI___sigprocmask sigprocmask.c:26
    #4 0x7fc12ff2601b in __longjmp_chk longjmp.c:36
    #5 0x55788c6210c0 in print_test_result.isra.0 builtin-test.c:0
    #6 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
    #7 0x7fc12fe99687 in __internal_syscall_cancel cancellation.c:64
    #8 0x7fc12fee5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72
    #9 0x7fc12fef1393 in __nanosleep nanosleep.c:26
    #10 0x7fc12ff02d68 in __sleep sleep.c:55
    #11 0x55788c63196b in test__PERF_RECORD perf-record.c:0
    #12 0x55788c620fb0 in run_test_child builtin-test.c:0
    #13 0x55788c5bd18d in start_command run-command.c:127
    #14 0x55788c621ef3 in __cmd_test builtin-test.c:0
    #15 0x55788c6225bf in cmd_test ??:0
    #16 0x55788c5afbd0 in run_builtin perf.c:0
    #17 0x55788c5afeeb in handle_internal_command perf.c:0
    #18 0x55788c52b383 in main ??:0
    #19 0x7fc12fe33ca8 in __libc_start_call_main libc_start_call_main.h:74
    #20 0x7fc12fe33d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
    #21 0x55788c52b9d1 in _start ??:0
  7: PERF_RECORD_* events & perf_sample fields                       : Skip (permissions)
```

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250624210500.2121303-1-irogers@google.com


Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
parent 51f4c004

tools/perf/tests/builtin-test.c

+14 −1
Original line number Diff line number Diff line
@@ -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;

	}

tools/perf/ui/tui/setup.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

}

tools/perf/util/debug.c

+57 −11
Original line number Diff line number Diff line
@@ -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 +305,60 @@ 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);



#ifdef HAVE_BACKTRACE_SUPPORT

	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;

	}

#endif



	for (size_t i = 0; i < stackdump_size; i++) {

		struct addr_location al;

		u64 addr = (u64)(uintptr_t)stackdump[i];

		bool printed = false;



		addr_location__init(&al);

		if (thread && thread__find_map(thread, PERF_RECORD_MISC_USER, addr, &al)) {

			al.sym = map__find_symbol(al.map, al.addr);

			if (al.sym) {

				fprintf(file, "    #%zd %p in %s ", i, stackdump[i], al.sym->name);

				printed = true;

			}

		}

		if (!printed)

			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) {}

tools/perf/util/debug.h

+1 −0
Original line number Diff line number Diff line
@@ -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);