* [PATCH v2 1/2] perf machine: Factor creating a "live" machine out of dwarf-unwind @ 2025-05-29 5:23 Ian Rogers 2025-05-29 5:23 ` [PATCH v2 2/2] perf debug: Add function symbols to dump_stack Ian Rogers 0 siblings, 1 reply; 7+ messages in thread From: Ian Rogers @ 2025-05-29 5:23 UTC (permalink / raw) To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa, Ian Rogers, Adrian Hunter, Kan Liang, James Clark, Howard Chu, Yicong Yang, Michael Petlan, Andi Kleen, Christophe Leroy, Dr. David Alan Gilbert, Krzysztof Łopatowski, Dmitry Vyukov, linux-perf-users, linux-kernel Factor out for use in places other than the dwarf unwinding tests for libunwind. Signed-off-by: Ian Rogers <irogers@google.com> --- tools/perf/tests/dwarf-unwind.c | 35 ++++------------------ tools/perf/util/machine.c | 53 +++++++++++++++++++++++++++------ tools/perf/util/machine.h | 1 + 3 files changed, 51 insertions(+), 38 deletions(-) diff --git a/tools/perf/tests/dwarf-unwind.c b/tools/perf/tests/dwarf-unwind.c index 4803ab2d97ba..525c46b7971a 100644 --- a/tools/perf/tests/dwarf-unwind.c +++ b/tools/perf/tests/dwarf-unwind.c @@ -15,7 +15,6 @@ #include "symbol.h" #include "thread.h" #include "callchain.h" -#include "util/synthetic-events.h" /* For bsearch. We try to unwind functions in shared object. */ #include <stdlib.h> @@ -37,24 +36,6 @@ #define NO_TAIL_CALL_BARRIER __asm__ __volatile__("" : : : "memory"); #endif -static int mmap_handler(const struct perf_tool *tool __maybe_unused, - union perf_event *event, - struct perf_sample *sample, - struct machine *machine) -{ - return machine__process_mmap2_event(machine, event, sample); -} - -static int init_live_machine(struct machine *machine) -{ - union perf_event event; - pid_t pid = getpid(); - - memset(&event, 0, sizeof(event)); - return perf_event__synthesize_mmap_events(NULL, &event, pid, pid, - mmap_handler, machine, true); -} - /* * We need to keep these functions global, despite the * fact that they are used only locally in this object, @@ -202,8 +183,12 @@ noinline int test__dwarf_unwind(struct test_suite *test __maybe_unused, struct machine *machine; struct thread *thread; int err = -1; + pid_t pid = getpid(); - machine = machine__new_host(); + callchain_param.record_mode = CALLCHAIN_DWARF; + dwarf_callchain_users = true; + + machine = machine__new_live(/*kernel_maps=*/true, pid); if (!machine) { pr_err("Could not get machine\n"); return -1; @@ -214,18 +199,10 @@ noinline int test__dwarf_unwind(struct test_suite *test __maybe_unused, return -1; } - callchain_param.record_mode = CALLCHAIN_DWARF; - dwarf_callchain_users = true; - - if (init_live_machine(machine)) { - pr_err("Could not init machine\n"); - goto out; - } - if (verbose > 1) machine__fprintf(machine, stderr); - thread = machine__find_thread(machine, getpid(), getpid()); + thread = machine__find_thread(machine, pid, pid); if (!thread) { pr_err("Could not get thread\n"); goto out; diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 2531b373f2cf..c5e28d15323f 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -20,6 +20,7 @@ #include "path.h" #include "srcline.h" #include "symbol.h" +#include "synthetic-events.h" #include "sort.h" #include "strlist.h" #include "target.h" @@ -128,23 +129,57 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid) return 0; } -struct machine *machine__new_host(void) +static struct machine *__machine__new_host(bool kernel_maps) { struct machine *machine = malloc(sizeof(*machine)); - if (machine != NULL) { - machine__init(machine, "", HOST_KERNEL_ID); + if (!machine) + return NULL; - if (machine__create_kernel_maps(machine) < 0) - goto out_delete; + machine__init(machine, "", HOST_KERNEL_ID); - machine->env = &perf_env; + if (kernel_maps && machine__create_kernel_maps(machine) < 0) { + free(machine); + return NULL; } + machine->env = &perf_env; + return machine; +} + +struct machine *machine__new_host(void) +{ + return __machine__new_host(/*kernel_maps=*/true); +} + +static int mmap_handler(const struct perf_tool *tool __maybe_unused, + union perf_event *event, + struct perf_sample *sample, + struct machine *machine) +{ + return machine__process_mmap2_event(machine, event, sample); +} +static int machine__init_live(struct machine *machine, pid_t pid) +{ + union perf_event event; + + memset(&event, 0, sizeof(event)); + return perf_event__synthesize_mmap_events(NULL, &event, pid, pid, + mmap_handler, machine, true); +} + +struct machine *machine__new_live(bool kernel_maps, pid_t pid) +{ + struct machine *machine = __machine__new_host(kernel_maps); + + if (!machine) + return NULL; + + if (machine__init_live(machine, pid)) { + machine__delete(machine); + return NULL; + } return machine; -out_delete: - free(machine); - return NULL; } struct machine *machine__new_kallsyms(void) diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h index b56abec84fed..180b369c366c 100644 --- a/tools/perf/util/machine.h +++ b/tools/perf/util/machine.h @@ -171,6 +171,7 @@ void machines__set_comm_exec(struct machines *machines, bool comm_exec); struct machine *machine__new_host(void); struct machine *machine__new_kallsyms(void); +struct machine *machine__new_live(bool kernel_maps, pid_t pid); int machine__init(struct machine *machine, const char *root_dir, pid_t pid); void machine__exit(struct machine *machine); void machine__delete_threads(struct machine *machine); -- 2.49.0.1204.g71687c7c1d-goog ^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 2/2] perf debug: Add function symbols to dump_stack 2025-05-29 5:23 [PATCH v2 1/2] perf machine: Factor creating a "live" machine out of dwarf-unwind Ian Rogers @ 2025-05-29 5:23 ` Ian Rogers 2025-05-29 20:21 ` Arnaldo Carvalho de Melo 0 siblings, 1 reply; 7+ messages in thread From: Ian Rogers @ 2025-05-29 5:23 UTC (permalink / raw) To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa, Ian Rogers, Adrian Hunter, Kan Liang, James Clark, Howard Chu, Yicong Yang, Michael Petlan, Andi Kleen, Christophe Leroy, Dr. David Alan Gilbert, Krzysztof Łopatowski, Dmitry Vyukov, linux-perf-users, linux-kernel 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> --- v2: Fix NO_BACKTRACE=1 build (Arnaldo) --- tools/perf/tests/builtin-test.c | 15 +++++++- tools/perf/ui/tui/setup.c | 2 +- tools/perf/util/debug.c | 68 +++++++++++++++++++++++++++------ tools/perf/util/debug.h | 1 + 4 files changed, 73 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..0c7c6a9e158b 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 +305,60 @@ 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)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) {} 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); -- 2.49.0.1204.g71687c7c1d-goog ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] perf debug: Add function symbols to dump_stack 2025-05-29 5:23 ` [PATCH v2 2/2] perf debug: Add function symbols to dump_stack Ian Rogers @ 2025-05-29 20:21 ` Arnaldo Carvalho de Melo 2025-05-29 22:02 ` Ian Rogers 0 siblings, 1 reply; 7+ messages in thread From: Arnaldo Carvalho de Melo @ 2025-05-29 20:21 UTC (permalink / raw) To: Ian Rogers Cc: Peter Zijlstra, Ingo Molnar, Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa, Adrian Hunter, Kan Liang, James Clark, Howard Chu, Yicong Yang, Michael Petlan, Andi Kleen, Christophe Leroy, Dr. David Alan Gilbert, Krzysztof Łopatowski, Dmitry Vyukov, linux-perf-users, linux-kernel On Wed, May 28, 2025 at 10:23:22PM -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: So you are testing it with: root@number:~# perf test PERF_RECORD 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 : Skip (permissions) root@number:~# ? I built it with DEBUG=1 and without, and with your patch, following your example output, I'm not being able to reproduce. Tried it as well with: ⬢ [acme@toolbx perf-tools-next]$ cat segv.patch diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 8b30c6f16a9eeac1..e55d86f1097d6d79 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -402,6 +402,8 @@ static struct symbol *symbols__find(struct rb_root_cached *symbols, u64 ip) { struct rb_node *n; + *(int *)NULL = 0; + if (symbols == NULL) return NULL; ⬢ [acme@toolbx perf-tools-next]$ patch -p1 < segv.patch patching file tools/perf/util/symbol.c ⬢ [acme@toolbx perf-tools-next]$ m rm: cannot remove '/home/acme/libexec/perf-core/scripts/python/Perf-Trace-Util/lib/Perf/Trace/__pycache__/Core.cpython-313.pyc': Permission denied make: Entering directory '/home/acme/git/perf-tools-next/tools/perf' BUILD: Doing 'make -j32' parallel build Warning: Kernel ABI header differences: diff -u tools/arch/arm64/include/asm/cputype.h arch/arm64/include/asm/cputype.h Auto-detecting system features: ... libdw: [ on ] ... glibc: [ on ] ... libelf: [ on ] ... libnuma: [ on ] ... numa_num_possible_cpus: [ on ] ... libperl: [ on ] ... libpython: [ on ] ... libcrypto: [ on ] ... libcapstone: [ on ] ... llvm-perf: [ on ] ... zlib: [ on ] ... lzma: [ on ] ... get_cpuid: [ on ] ... bpf: [ on ] ... libaio: [ on ] ... libzstd: [ on ] INSTALL libsubcmd_headers INSTALL libperf_headers INSTALL libapi_headers INSTALL libsymbol_headers INSTALL libbpf_headers CC /tmp/build/perf-tools-next/util/symbol.o LD /tmp/build/perf-tools-next/util/perf-util-in.o LD /tmp/build/perf-tools-next/perf-util-in.o AR /tmp/build/perf-tools-next/libperf-util.a LINK /tmp/build/perf-tools-next/perf GEN /tmp/build/perf-tools-next/python/perf.cpython-313-x86_64-linux-gnu.so INSTALL binaries INSTALL tests INSTALL libperf-jvmti.so INSTALL libexec INSTALL perf-archive INSTALL perf-iostat INSTALL perl-scripts INSTALL python-scripts INSTALL dlfilters INSTALL perf_completion-script INSTALL perf-tip make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf' 18: 'import perf' in python : Ok ⬢ [acme@toolbx perf-tools-next]$ root@number:~# perf top perf: Segmentation fault -------- backtrace -------- Segmentation fault (core dumped) root@number:~# Tried also with this, but probably something else is at play: root@number:~# perf probe -x ~/bin/perf dump_stack Added new event: probe_perf:dump_stack (on dump_stack in /home/acme/bin/perf) You can now use it in all perf tools, such as: perf record -e probe_perf:dump_stack -aR sleep 1 root@number:~# root@number:~# perf trace -e probe_perf:dump_stack/max-stack=16/ perf top perf: Segmentation fault -------- backtrace -------- root@number:~# Running perf trace on a separate terminal it also doesn't catch dump_stack being called (that probe point). root@number:~# perf top --stdio PerfTop: 0 irqs/sec kernel: 0.0% exact: 0.0% lost: 0/0 drop: 0/0 [4000Hz cycles:P], (all, 32 CPUs) ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ perf: Segmentation fault Segmentation fault (core dumped) root@number:~# root@number:~# nm ~/bin/perf | grep dump_stack 0000000000637eaa T __dump_stack 00000000006380fa T dump_stack 000000000063816b T sighandler_dump_stack root@number:~# ⬢ [acme@toolbx perf-tools-next]$ rpm -q glibc glibc-2.41-5.fc42.x86_64 root@number:~# uname -a Linux number 6.14.8-300.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Thu May 22 19:26:02 UTC 2025 x86_64 GNU/Linux root@number:~# What am I missing? - Arnaldo > ____ 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> > --- > v2: Fix NO_BACKTRACE=1 build (Arnaldo) > --- > tools/perf/tests/builtin-test.c | 15 +++++++- > tools/perf/ui/tui/setup.c | 2 +- > tools/perf/util/debug.c | 68 +++++++++++++++++++++++++++------ > tools/perf/util/debug.h | 1 + > 4 files changed, 73 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..0c7c6a9e158b 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 +305,60 @@ 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)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) {} > 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); > > -- > 2.49.0.1204.g71687c7c1d-goog > ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] perf debug: Add function symbols to dump_stack 2025-05-29 20:21 ` Arnaldo Carvalho de Melo @ 2025-05-29 22:02 ` Ian Rogers 2025-06-02 17:32 ` Ian Rogers 0 siblings, 1 reply; 7+ messages in thread From: Ian Rogers @ 2025-05-29 22:02 UTC (permalink / raw) To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra, Ingo Molnar, Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa, Adrian Hunter, Kan Liang, James Clark, Howard Chu, Yicong Yang, Michael Petlan, Andi Kleen, Christophe Leroy, Dr. David Alan Gilbert, Krzysztof Łopatowski, Dmitry Vyukov, linux-perf-users, linux-kernel On Thu, May 29, 2025 at 1:21 PM Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > On Wed, May 28, 2025 at 10:23:22PM -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: > > So you are testing it with: > > root@number:~# perf test PERF_RECORD > 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 : Skip (permissions) > root@number:~# > > ? You are running the test as a child and by default the child test output is only displayed if verbose is enabled. I use verbose=2 below as verbose=1 won't display anything unless the child test gives a fail exit value: ``` $ git log --oneline b9ac06abfde9 perf debug: Add function symbols to dump_stack e561806265ed perf machine: Factor creating a "live" machine out of dwarf-unwind 628e124404b3 perf tests switch-tracking: Fix timestamp comparison $ make -C tools/perf O=/tmp/perf ... $ sudo /tmp/perf/perf test -vv PERF_RECORD 8: PERF_RECORD_* events & perf_sample fields: 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 0x5617ec45e5e3 in child_test_sig_handler builtin-test.c:0 #1 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 #2 0x7f855c699687 in __internal_syscall_cancel cancellation.c:64 #3 0x7f855c6e5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72 #4 0x7f855c6f1393 in __nanosleep nanosleep.c:26 #5 0x7f855c702d68 in __sleep sleep.c:55 #6 0x5617ec46ebfb in test__PERF_RECORD perf-record.c:0 #7 0x5617ec45e4f0 in run_test_child builtin-test.c:0 #8 0x5617ec3faf0d in start_command run-command.c:127 #9 0x5617ec45f433 in __cmd_test builtin-test.c:0 #10 0x5617ec45faff in cmd_test perf[147aff] #11 0x5617ec3ed960 in run_builtin perf.c:0 #12 0x5617ec3edc7b in handle_internal_command perf.c:0 #13 0x5617ec368d33 in main perf[50d33] #14 0x7f855c633ca8 in __libc_start_call_main libc_start_call_main.h:74 #15 0x7f855c633d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 #16 0x5617ec369381 in _start perf[51381] ---- unexpected signal (2) ---- #0 0x5617ec45e5e3 in child_test_sig_handler builtin-test.c:0 #1 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 #2 0x7f855c6a3a14 in pthread_sigmask@GLIBC_2.2.5 pthread_sigmask.c:45 #3 0x7f855c649fd9 in __GI___sigprocmask sigprocmask.c:26 #4 0x7f855c72601b in __longjmp_chk longjmp.c:36 #5 0x5617ec45e600 in print_test_result.isra.0 builtin-test.c:0 #6 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 #7 0x7f855c699687 in __internal_syscall_cancel cancellation.c:64 #8 0x7f855c6e5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72 #9 0x7f855c6f1393 in __nanosleep nanosleep.c:26 #10 0x7f855c702d68 in __sleep sleep.c:55 #11 0x5617ec46ebfb in test__PERF_RECORD perf-record.c:0 #12 0x5617ec45e4f0 in run_test_child builtin-test.c:0 #13 0x5617ec3faf0d in start_command run-command.c:127 #14 0x5617ec45f433 in __cmd_test builtin-test.c:0 #15 0x5617ec45faff in cmd_test perf[147aff] #16 0x5617ec3ed960 in run_builtin perf.c:0 #17 0x5617ec3edc7b in handle_internal_command perf.c:0 #18 0x5617ec368d33 in main perf[50d33] #19 0x7f855c633ca8 in __libc_start_call_main libc_start_call_main.h:74 #20 0x7f855c633d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 #21 0x5617ec369381 in _start perf[51381] 8: PERF_RECORD_* events & perf_sample fields : Skip (permissions) ``` > I built it with DEBUG=1 and without, and with your patch, following your > example output, I'm not being able to reproduce. > > Tried it as well with: > > ⬢ [acme@toolbx perf-tools-next]$ cat segv.patch > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > index 8b30c6f16a9eeac1..e55d86f1097d6d79 100644 > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c > @@ -402,6 +402,8 @@ static struct symbol *symbols__find(struct rb_root_cached *symbols, u64 ip) > { > struct rb_node *n; > > + *(int *)NULL = 0; > + > if (symbols == NULL) > return NULL; > > ⬢ [acme@toolbx perf-tools-next]$ patch -p1 < segv.patch > patching file tools/perf/util/symbol.c > ⬢ [acme@toolbx perf-tools-next]$ m > rm: cannot remove '/home/acme/libexec/perf-core/scripts/python/Perf-Trace-Util/lib/Perf/Trace/__pycache__/Core.cpython-313.pyc': Permission denied > make: Entering directory '/home/acme/git/perf-tools-next/tools/perf' > BUILD: Doing 'make -j32' parallel build > Warning: Kernel ABI header differences: > diff -u tools/arch/arm64/include/asm/cputype.h arch/arm64/include/asm/cputype.h > > Auto-detecting system features: > ... libdw: [ on ] > ... glibc: [ on ] > ... libelf: [ on ] > ... libnuma: [ on ] > ... numa_num_possible_cpus: [ on ] > ... libperl: [ on ] > ... libpython: [ on ] > ... libcrypto: [ on ] > ... libcapstone: [ on ] > ... llvm-perf: [ on ] > ... zlib: [ on ] > ... lzma: [ on ] > ... get_cpuid: [ on ] > ... bpf: [ on ] > ... libaio: [ on ] > ... libzstd: [ on ] > > INSTALL libsubcmd_headers > INSTALL libperf_headers > INSTALL libapi_headers > INSTALL libsymbol_headers > INSTALL libbpf_headers > CC /tmp/build/perf-tools-next/util/symbol.o > LD /tmp/build/perf-tools-next/util/perf-util-in.o > LD /tmp/build/perf-tools-next/perf-util-in.o > AR /tmp/build/perf-tools-next/libperf-util.a > LINK /tmp/build/perf-tools-next/perf > GEN /tmp/build/perf-tools-next/python/perf.cpython-313-x86_64-linux-gnu.so > INSTALL binaries > INSTALL tests > INSTALL libperf-jvmti.so > INSTALL libexec > INSTALL perf-archive > INSTALL perf-iostat > INSTALL perl-scripts > INSTALL python-scripts > INSTALL dlfilters > INSTALL perf_completion-script > INSTALL perf-tip > make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf' > 18: 'import perf' in python : Ok > ⬢ [acme@toolbx perf-tools-next]$ > > root@number:~# perf top > perf: Segmentation fault > -------- backtrace -------- > Segmentation fault (core dumped) > root@number:~# > > Tried also with this, but probably something else is at play: > > root@number:~# perf probe -x ~/bin/perf dump_stack > Added new event: > probe_perf:dump_stack (on dump_stack in /home/acme/bin/perf) > > You can now use it in all perf tools, such as: > > perf record -e probe_perf:dump_stack -aR sleep 1 > > root@number:~# > root@number:~# perf trace -e probe_perf:dump_stack/max-stack=16/ perf top > perf: Segmentation fault > -------- backtrace -------- > root@number:~# > > Running perf trace on a separate terminal it also doesn't catch > dump_stack being called (that probe point). > > root@number:~# perf top --stdio > PerfTop: 0 irqs/sec kernel: 0.0% exact: 0.0% lost: 0/0 drop: 0/0 [4000Hz cycles:P], (all, 32 CPUs) > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ > > perf: Segmentation fault > Segmentation fault (core dumped) > root@number:~# > > root@number:~# nm ~/bin/perf | grep dump_stack > 0000000000637eaa T __dump_stack > 00000000006380fa T dump_stack > 000000000063816b T sighandler_dump_stack > root@number:~# > > ⬢ [acme@toolbx perf-tools-next]$ rpm -q glibc > glibc-2.41-5.fc42.x86_64 > root@number:~# uname -a > Linux number 6.14.8-300.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Thu May 22 19:26:02 UTC 2025 x86_64 GNU/Linux > root@number:~# > > What am I missing? For perf top I can do: ``` $ sudo /tmp/perf/perf top ``` in a different terminal: ``` $ sudo killall -11 perf ``` then back in the first terminal: ``` perf: Segmentation fault -------- backtrace -------- #0 0x55ee68647918 in ui__signal_backtrace setup.c:110 #1 0x7fe2d3849df0 in __restore_rt libc_sigaction.c:0 #2 0x7fe2d38a49ee in __syscall_cancel_arch syscall_cancel.S:56 #3 0x7fe2d3899668 in __internal_syscall_cancel cancellation.c:54 #4 0x7fe2d38996ad in __syscall_cancel cancellation.c:79 #5 0x7fe2d390d9c6 in __poll poll.c:43 #6 0x55ee6855dfcb in fdarray__poll array.c:139 #7 0x55ee68565a05 in perf_evlist__poll evlist.c:391 #8 0x55ee68673b5a in evlist__poll evlist.c:594 #9 0x55ee684e7a61 in __cmd_top builtin-top.c:1369 #10 0x55ee684e9a6c in cmd_top builtin-top.c:1856 #11 0x55ee6855d1f0 in run_builtin perf.c:351 #12 0x55ee6855d497 in handle_internal_command perf.c:404 #13 0x55ee6855d5f0 in run_argv perf.c:451 #14 0x55ee6855d939 in main perf.c:558 #15 0x7fe2d3833ca8 in __libc_start_call_main libc_start_call_main.h:74 #16 0x7fe2d3833d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 #17 0x55ee684b0a91 in _start perf[4ca91] ``` As the same symbol code is used for the backtrace then adding the segv there is likely causing a segv in the signal handler in __dump_stack. Thanks, Ian > - Arnaldo > > > ____ 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> > > --- > > v2: Fix NO_BACKTRACE=1 build (Arnaldo) > > --- > > tools/perf/tests/builtin-test.c | 15 +++++++- > > tools/perf/ui/tui/setup.c | 2 +- > > tools/perf/util/debug.c | 68 +++++++++++++++++++++++++++------ > > tools/perf/util/debug.h | 1 + > > 4 files changed, 73 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..0c7c6a9e158b 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 +305,60 @@ 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)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) {} > > 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); > > > > -- > > 2.49.0.1204.g71687c7c1d-goog > > ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] perf debug: Add function symbols to dump_stack 2025-05-29 22:02 ` Ian Rogers @ 2025-06-02 17:32 ` Ian Rogers 2025-06-03 21:55 ` Ian Rogers 0 siblings, 1 reply; 7+ messages in thread From: Ian Rogers @ 2025-06-02 17:32 UTC (permalink / raw) To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra, Ingo Molnar, Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa, Adrian Hunter, Kan Liang, James Clark, Howard Chu, Yicong Yang, Michael Petlan, Andi Kleen, Christophe Leroy, Dr. David Alan Gilbert, Krzysztof Łopatowski, Dmitry Vyukov, linux-perf-users, linux-kernel On Thu, May 29, 2025 at 3:02 PM Ian Rogers <irogers@google.com> wrote: > > On Thu, May 29, 2025 at 1:21 PM Arnaldo Carvalho de Melo > <acme@kernel.org> wrote: > > > > On Wed, May 28, 2025 at 10:23:22PM -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: > > > > So you are testing it with: > > > > root@number:~# perf test PERF_RECORD > > 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 : Skip (permissions) > > root@number:~# > > > > ? > > You are running the test as a child and by default the child test > output is only displayed if verbose is enabled. I use verbose=2 below > as verbose=1 won't display anything unless the child test gives a fail > exit value: > ``` > $ git log --oneline > b9ac06abfde9 perf debug: Add function symbols to dump_stack > e561806265ed perf machine: Factor creating a "live" machine out of dwarf-unwind > 628e124404b3 perf tests switch-tracking: Fix timestamp comparison > $ make -C tools/perf O=/tmp/perf > ... > $ sudo /tmp/perf/perf test -vv PERF_RECORD > 8: PERF_RECORD_* events & perf_sample fields: > 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 0x5617ec45e5e3 in child_test_sig_handler builtin-test.c:0 > #1 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > #2 0x7f855c699687 in __internal_syscall_cancel cancellation.c:64 > #3 0x7f855c6e5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72 > #4 0x7f855c6f1393 in __nanosleep nanosleep.c:26 > #5 0x7f855c702d68 in __sleep sleep.c:55 > #6 0x5617ec46ebfb in test__PERF_RECORD perf-record.c:0 > #7 0x5617ec45e4f0 in run_test_child builtin-test.c:0 > #8 0x5617ec3faf0d in start_command run-command.c:127 > #9 0x5617ec45f433 in __cmd_test builtin-test.c:0 > #10 0x5617ec45faff in cmd_test perf[147aff] > #11 0x5617ec3ed960 in run_builtin perf.c:0 > #12 0x5617ec3edc7b in handle_internal_command perf.c:0 > #13 0x5617ec368d33 in main perf[50d33] > #14 0x7f855c633ca8 in __libc_start_call_main libc_start_call_main.h:74 > #15 0x7f855c633d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > #16 0x5617ec369381 in _start perf[51381] > > ---- unexpected signal (2) ---- > #0 0x5617ec45e5e3 in child_test_sig_handler builtin-test.c:0 > #1 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > #2 0x7f855c6a3a14 in pthread_sigmask@GLIBC_2.2.5 pthread_sigmask.c:45 > #3 0x7f855c649fd9 in __GI___sigprocmask sigprocmask.c:26 > #4 0x7f855c72601b in __longjmp_chk longjmp.c:36 > #5 0x5617ec45e600 in print_test_result.isra.0 builtin-test.c:0 > #6 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > #7 0x7f855c699687 in __internal_syscall_cancel cancellation.c:64 > #8 0x7f855c6e5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72 > #9 0x7f855c6f1393 in __nanosleep nanosleep.c:26 > #10 0x7f855c702d68 in __sleep sleep.c:55 > #11 0x5617ec46ebfb in test__PERF_RECORD perf-record.c:0 > #12 0x5617ec45e4f0 in run_test_child builtin-test.c:0 > #13 0x5617ec3faf0d in start_command run-command.c:127 > #14 0x5617ec45f433 in __cmd_test builtin-test.c:0 > #15 0x5617ec45faff in cmd_test perf[147aff] > #16 0x5617ec3ed960 in run_builtin perf.c:0 > #17 0x5617ec3edc7b in handle_internal_command perf.c:0 > #18 0x5617ec368d33 in main perf[50d33] > #19 0x7f855c633ca8 in __libc_start_call_main libc_start_call_main.h:74 > #20 0x7f855c633d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > #21 0x5617ec369381 in _start perf[51381] > 8: PERF_RECORD_* events & perf_sample fields : > Skip (permissions) > ``` > > > > I built it with DEBUG=1 and without, and with your patch, following your > > example output, I'm not being able to reproduce. > > > > Tried it as well with: > > > > ⬢ [acme@toolbx perf-tools-next]$ cat segv.patch > > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > > index 8b30c6f16a9eeac1..e55d86f1097d6d79 100644 > > --- a/tools/perf/util/symbol.c > > +++ b/tools/perf/util/symbol.c > > @@ -402,6 +402,8 @@ static struct symbol *symbols__find(struct rb_root_cached *symbols, u64 ip) > > { > > struct rb_node *n; > > > > + *(int *)NULL = 0; > > + > > if (symbols == NULL) > > return NULL; > > > > ⬢ [acme@toolbx perf-tools-next]$ patch -p1 < segv.patch > > patching file tools/perf/util/symbol.c > > ⬢ [acme@toolbx perf-tools-next]$ m > > rm: cannot remove '/home/acme/libexec/perf-core/scripts/python/Perf-Trace-Util/lib/Perf/Trace/__pycache__/Core.cpython-313.pyc': Permission denied > > make: Entering directory '/home/acme/git/perf-tools-next/tools/perf' > > BUILD: Doing 'make -j32' parallel build > > Warning: Kernel ABI header differences: > > diff -u tools/arch/arm64/include/asm/cputype.h arch/arm64/include/asm/cputype.h > > > > Auto-detecting system features: > > ... libdw: [ on ] > > ... glibc: [ on ] > > ... libelf: [ on ] > > ... libnuma: [ on ] > > ... numa_num_possible_cpus: [ on ] > > ... libperl: [ on ] > > ... libpython: [ on ] > > ... libcrypto: [ on ] > > ... libcapstone: [ on ] > > ... llvm-perf: [ on ] > > ... zlib: [ on ] > > ... lzma: [ on ] > > ... get_cpuid: [ on ] > > ... bpf: [ on ] > > ... libaio: [ on ] > > ... libzstd: [ on ] > > > > INSTALL libsubcmd_headers > > INSTALL libperf_headers > > INSTALL libapi_headers > > INSTALL libsymbol_headers > > INSTALL libbpf_headers > > CC /tmp/build/perf-tools-next/util/symbol.o > > LD /tmp/build/perf-tools-next/util/perf-util-in.o > > LD /tmp/build/perf-tools-next/perf-util-in.o > > AR /tmp/build/perf-tools-next/libperf-util.a > > LINK /tmp/build/perf-tools-next/perf > > GEN /tmp/build/perf-tools-next/python/perf.cpython-313-x86_64-linux-gnu.so > > INSTALL binaries > > INSTALL tests > > INSTALL libperf-jvmti.so > > INSTALL libexec > > INSTALL perf-archive > > INSTALL perf-iostat > > INSTALL perl-scripts > > INSTALL python-scripts > > INSTALL dlfilters > > INSTALL perf_completion-script > > INSTALL perf-tip > > make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf' > > 18: 'import perf' in python : Ok > > ⬢ [acme@toolbx perf-tools-next]$ > > > > root@number:~# perf top > > perf: Segmentation fault > > -------- backtrace -------- > > Segmentation fault (core dumped) > > root@number:~# > > > > Tried also with this, but probably something else is at play: > > > > root@number:~# perf probe -x ~/bin/perf dump_stack > > Added new event: > > probe_perf:dump_stack (on dump_stack in /home/acme/bin/perf) > > > > You can now use it in all perf tools, such as: > > > > perf record -e probe_perf:dump_stack -aR sleep 1 > > > > root@number:~# > > root@number:~# perf trace -e probe_perf:dump_stack/max-stack=16/ perf top > > perf: Segmentation fault > > -------- backtrace -------- > > root@number:~# > > > > Running perf trace on a separate terminal it also doesn't catch > > dump_stack being called (that probe point). > > > > root@number:~# perf top --stdio > > PerfTop: 0 irqs/sec kernel: 0.0% exact: 0.0% lost: 0/0 drop: 0/0 [4000Hz cycles:P], (all, 32 CPUs) > > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ > > > > perf: Segmentation fault > > Segmentation fault (core dumped) > > root@number:~# > > > > root@number:~# nm ~/bin/perf | grep dump_stack > > 0000000000637eaa T __dump_stack > > 00000000006380fa T dump_stack > > 000000000063816b T sighandler_dump_stack > > root@number:~# > > > > ⬢ [acme@toolbx perf-tools-next]$ rpm -q glibc > > glibc-2.41-5.fc42.x86_64 > > root@number:~# uname -a > > Linux number 6.14.8-300.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Thu May 22 19:26:02 UTC 2025 x86_64 GNU/Linux > > root@number:~# > > > > What am I missing? > > For perf top I can do: > ``` > $ sudo /tmp/perf/perf top > ``` > in a different terminal: > ``` > $ sudo killall -11 perf > ``` > then back in the first terminal: > ``` > perf: Segmentation fault > -------- backtrace -------- > #0 0x55ee68647918 in ui__signal_backtrace setup.c:110 > #1 0x7fe2d3849df0 in __restore_rt libc_sigaction.c:0 > #2 0x7fe2d38a49ee in __syscall_cancel_arch syscall_cancel.S:56 > #3 0x7fe2d3899668 in __internal_syscall_cancel cancellation.c:54 > #4 0x7fe2d38996ad in __syscall_cancel cancellation.c:79 > #5 0x7fe2d390d9c6 in __poll poll.c:43 > #6 0x55ee6855dfcb in fdarray__poll array.c:139 > #7 0x55ee68565a05 in perf_evlist__poll evlist.c:391 > #8 0x55ee68673b5a in evlist__poll evlist.c:594 > #9 0x55ee684e7a61 in __cmd_top builtin-top.c:1369 > #10 0x55ee684e9a6c in cmd_top builtin-top.c:1856 > #11 0x55ee6855d1f0 in run_builtin perf.c:351 > #12 0x55ee6855d497 in handle_internal_command perf.c:404 > #13 0x55ee6855d5f0 in run_argv perf.c:451 > #14 0x55ee6855d939 in main perf.c:558 > #15 0x7fe2d3833ca8 in __libc_start_call_main libc_start_call_main.h:74 > #16 0x7fe2d3833d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > #17 0x55ee684b0a91 in _start perf[4ca91] > ``` > As the same symbol code is used for the backtrace then adding the segv > there is likely causing a segv in the signal handler in __dump_stack. Just to note, it would be nice for this to land as I need to rebase: https://lore.kernel.org/lkml/20250529044000.759937-19-irogers@google.com/ due to the machine changes. I believe the patches are WAI as shown in the output. Thanks, Ian > Thanks, > Ian > > > - Arnaldo > > > > > ____ 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> > > > --- > > > v2: Fix NO_BACKTRACE=1 build (Arnaldo) > > > --- > > > tools/perf/tests/builtin-test.c | 15 +++++++- > > > tools/perf/ui/tui/setup.c | 2 +- > > > tools/perf/util/debug.c | 68 +++++++++++++++++++++++++++------ > > > tools/perf/util/debug.h | 1 + > > > 4 files changed, 73 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..0c7c6a9e158b 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 +305,60 @@ 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)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) {} > > > 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); > > > > > > -- > > > 2.49.0.1204.g71687c7c1d-goog > > > ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] perf debug: Add function symbols to dump_stack 2025-06-02 17:32 ` Ian Rogers @ 2025-06-03 21:55 ` Ian Rogers 2025-06-11 22:05 ` Ian Rogers 0 siblings, 1 reply; 7+ messages in thread From: Ian Rogers @ 2025-06-03 21:55 UTC (permalink / raw) To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra, Ingo Molnar, Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa, Adrian Hunter, Kan Liang, James Clark, Howard Chu, Yicong Yang, Michael Petlan, Andi Kleen, Christophe Leroy, Dr. David Alan Gilbert, Krzysztof Łopatowski, Dmitry Vyukov, linux-perf-users, linux-kernel On Mon, Jun 2, 2025 at 10:32 AM Ian Rogers <irogers@google.com> wrote: > > On Thu, May 29, 2025 at 3:02 PM Ian Rogers <irogers@google.com> wrote: > > > > On Thu, May 29, 2025 at 1:21 PM Arnaldo Carvalho de Melo > > <acme@kernel.org> wrote: > > > > > > On Wed, May 28, 2025 at 10:23:22PM -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: > > > > > > So you are testing it with: > > > > > > root@number:~# perf test PERF_RECORD > > > 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 : Skip (permissions) > > > root@number:~# > > > > > > ? > > > > You are running the test as a child and by default the child test > > output is only displayed if verbose is enabled. I use verbose=2 below > > as verbose=1 won't display anything unless the child test gives a fail > > exit value: > > ``` > > $ git log --oneline > > b9ac06abfde9 perf debug: Add function symbols to dump_stack > > e561806265ed perf machine: Factor creating a "live" machine out of dwarf-unwind > > 628e124404b3 perf tests switch-tracking: Fix timestamp comparison > > $ make -C tools/perf O=/tmp/perf > > ... > > $ sudo /tmp/perf/perf test -vv PERF_RECORD > > 8: PERF_RECORD_* events & perf_sample fields: > > 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 0x5617ec45e5e3 in child_test_sig_handler builtin-test.c:0 > > #1 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > > #2 0x7f855c699687 in __internal_syscall_cancel cancellation.c:64 > > #3 0x7f855c6e5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72 > > #4 0x7f855c6f1393 in __nanosleep nanosleep.c:26 > > #5 0x7f855c702d68 in __sleep sleep.c:55 > > #6 0x5617ec46ebfb in test__PERF_RECORD perf-record.c:0 > > #7 0x5617ec45e4f0 in run_test_child builtin-test.c:0 > > #8 0x5617ec3faf0d in start_command run-command.c:127 > > #9 0x5617ec45f433 in __cmd_test builtin-test.c:0 > > #10 0x5617ec45faff in cmd_test perf[147aff] > > #11 0x5617ec3ed960 in run_builtin perf.c:0 > > #12 0x5617ec3edc7b in handle_internal_command perf.c:0 > > #13 0x5617ec368d33 in main perf[50d33] > > #14 0x7f855c633ca8 in __libc_start_call_main libc_start_call_main.h:74 > > #15 0x7f855c633d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > > #16 0x5617ec369381 in _start perf[51381] > > > > ---- unexpected signal (2) ---- > > #0 0x5617ec45e5e3 in child_test_sig_handler builtin-test.c:0 > > #1 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > > #2 0x7f855c6a3a14 in pthread_sigmask@GLIBC_2.2.5 pthread_sigmask.c:45 > > #3 0x7f855c649fd9 in __GI___sigprocmask sigprocmask.c:26 > > #4 0x7f855c72601b in __longjmp_chk longjmp.c:36 > > #5 0x5617ec45e600 in print_test_result.isra.0 builtin-test.c:0 > > #6 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > > #7 0x7f855c699687 in __internal_syscall_cancel cancellation.c:64 > > #8 0x7f855c6e5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72 > > #9 0x7f855c6f1393 in __nanosleep nanosleep.c:26 > > #10 0x7f855c702d68 in __sleep sleep.c:55 > > #11 0x5617ec46ebfb in test__PERF_RECORD perf-record.c:0 > > #12 0x5617ec45e4f0 in run_test_child builtin-test.c:0 > > #13 0x5617ec3faf0d in start_command run-command.c:127 > > #14 0x5617ec45f433 in __cmd_test builtin-test.c:0 > > #15 0x5617ec45faff in cmd_test perf[147aff] > > #16 0x5617ec3ed960 in run_builtin perf.c:0 > > #17 0x5617ec3edc7b in handle_internal_command perf.c:0 > > #18 0x5617ec368d33 in main perf[50d33] > > #19 0x7f855c633ca8 in __libc_start_call_main libc_start_call_main.h:74 > > #20 0x7f855c633d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > > #21 0x5617ec369381 in _start perf[51381] > > 8: PERF_RECORD_* events & perf_sample fields : > > Skip (permissions) > > ``` > > > > > > > I built it with DEBUG=1 and without, and with your patch, following your > > > example output, I'm not being able to reproduce. > > > > > > Tried it as well with: > > > > > > ⬢ [acme@toolbx perf-tools-next]$ cat segv.patch > > > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > > > index 8b30c6f16a9eeac1..e55d86f1097d6d79 100644 > > > --- a/tools/perf/util/symbol.c > > > +++ b/tools/perf/util/symbol.c > > > @@ -402,6 +402,8 @@ static struct symbol *symbols__find(struct rb_root_cached *symbols, u64 ip) > > > { > > > struct rb_node *n; > > > > > > + *(int *)NULL = 0; > > > + > > > if (symbols == NULL) > > > return NULL; > > > > > > ⬢ [acme@toolbx perf-tools-next]$ patch -p1 < segv.patch > > > patching file tools/perf/util/symbol.c > > > ⬢ [acme@toolbx perf-tools-next]$ m > > > rm: cannot remove '/home/acme/libexec/perf-core/scripts/python/Perf-Trace-Util/lib/Perf/Trace/__pycache__/Core.cpython-313.pyc': Permission denied > > > make: Entering directory '/home/acme/git/perf-tools-next/tools/perf' > > > BUILD: Doing 'make -j32' parallel build > > > Warning: Kernel ABI header differences: > > > diff -u tools/arch/arm64/include/asm/cputype.h arch/arm64/include/asm/cputype.h > > > > > > Auto-detecting system features: > > > ... libdw: [ on ] > > > ... glibc: [ on ] > > > ... libelf: [ on ] > > > ... libnuma: [ on ] > > > ... numa_num_possible_cpus: [ on ] > > > ... libperl: [ on ] > > > ... libpython: [ on ] > > > ... libcrypto: [ on ] > > > ... libcapstone: [ on ] > > > ... llvm-perf: [ on ] > > > ... zlib: [ on ] > > > ... lzma: [ on ] > > > ... get_cpuid: [ on ] > > > ... bpf: [ on ] > > > ... libaio: [ on ] > > > ... libzstd: [ on ] > > > > > > INSTALL libsubcmd_headers > > > INSTALL libperf_headers > > > INSTALL libapi_headers > > > INSTALL libsymbol_headers > > > INSTALL libbpf_headers > > > CC /tmp/build/perf-tools-next/util/symbol.o > > > LD /tmp/build/perf-tools-next/util/perf-util-in.o > > > LD /tmp/build/perf-tools-next/perf-util-in.o > > > AR /tmp/build/perf-tools-next/libperf-util.a > > > LINK /tmp/build/perf-tools-next/perf > > > GEN /tmp/build/perf-tools-next/python/perf.cpython-313-x86_64-linux-gnu.so > > > INSTALL binaries > > > INSTALL tests > > > INSTALL libperf-jvmti.so > > > INSTALL libexec > > > INSTALL perf-archive > > > INSTALL perf-iostat > > > INSTALL perl-scripts > > > INSTALL python-scripts > > > INSTALL dlfilters > > > INSTALL perf_completion-script > > > INSTALL perf-tip > > > make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf' > > > 18: 'import perf' in python : Ok > > > ⬢ [acme@toolbx perf-tools-next]$ > > > > > > root@number:~# perf top > > > perf: Segmentation fault > > > -------- backtrace -------- > > > Segmentation fault (core dumped) > > > root@number:~# > > > > > > Tried also with this, but probably something else is at play: > > > > > > root@number:~# perf probe -x ~/bin/perf dump_stack > > > Added new event: > > > probe_perf:dump_stack (on dump_stack in /home/acme/bin/perf) > > > > > > You can now use it in all perf tools, such as: > > > > > > perf record -e probe_perf:dump_stack -aR sleep 1 > > > > > > root@number:~# > > > root@number:~# perf trace -e probe_perf:dump_stack/max-stack=16/ perf top > > > perf: Segmentation fault > > > -------- backtrace -------- > > > root@number:~# > > > > > > Running perf trace on a separate terminal it also doesn't catch > > > dump_stack being called (that probe point). > > > > > > root@number:~# perf top --stdio > > > PerfTop: 0 irqs/sec kernel: 0.0% exact: 0.0% lost: 0/0 drop: 0/0 [4000Hz cycles:P], (all, 32 CPUs) > > > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ > > > > > > perf: Segmentation fault > > > Segmentation fault (core dumped) > > > root@number:~# > > > > > > root@number:~# nm ~/bin/perf | grep dump_stack > > > 0000000000637eaa T __dump_stack > > > 00000000006380fa T dump_stack > > > 000000000063816b T sighandler_dump_stack > > > root@number:~# > > > > > > ⬢ [acme@toolbx perf-tools-next]$ rpm -q glibc > > > glibc-2.41-5.fc42.x86_64 > > > root@number:~# uname -a > > > Linux number 6.14.8-300.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Thu May 22 19:26:02 UTC 2025 x86_64 GNU/Linux > > > root@number:~# > > > > > > What am I missing? > > > > For perf top I can do: > > ``` > > $ sudo /tmp/perf/perf top > > ``` > > in a different terminal: > > ``` > > $ sudo killall -11 perf > > ``` > > then back in the first terminal: > > ``` > > perf: Segmentation fault > > -------- backtrace -------- > > #0 0x55ee68647918 in ui__signal_backtrace setup.c:110 > > #1 0x7fe2d3849df0 in __restore_rt libc_sigaction.c:0 > > #2 0x7fe2d38a49ee in __syscall_cancel_arch syscall_cancel.S:56 > > #3 0x7fe2d3899668 in __internal_syscall_cancel cancellation.c:54 > > #4 0x7fe2d38996ad in __syscall_cancel cancellation.c:79 > > #5 0x7fe2d390d9c6 in __poll poll.c:43 > > #6 0x55ee6855dfcb in fdarray__poll array.c:139 > > #7 0x55ee68565a05 in perf_evlist__poll evlist.c:391 > > #8 0x55ee68673b5a in evlist__poll evlist.c:594 > > #9 0x55ee684e7a61 in __cmd_top builtin-top.c:1369 > > #10 0x55ee684e9a6c in cmd_top builtin-top.c:1856 > > #11 0x55ee6855d1f0 in run_builtin perf.c:351 > > #12 0x55ee6855d497 in handle_internal_command perf.c:404 > > #13 0x55ee6855d5f0 in run_argv perf.c:451 > > #14 0x55ee6855d939 in main perf.c:558 > > #15 0x7fe2d3833ca8 in __libc_start_call_main libc_start_call_main.h:74 > > #16 0x7fe2d3833d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > > #17 0x55ee684b0a91 in _start perf[4ca91] > > ``` > > As the same symbol code is used for the backtrace then adding the segv > > there is likely causing a segv in the signal handler in __dump_stack. > > Just to note, it would be nice for this to land as I need to rebase: > https://lore.kernel.org/lkml/20250529044000.759937-19-irogers@google.com/ > due to the machine changes. I believe the patches are WAI as shown in > the output. Ok, I see this made it into v6.16 PR: https://lore.kernel.org/lkml/20250603203501.1961487-1-acme@kernel.org/ Thanks Arnaldo! Ian ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/2] perf debug: Add function symbols to dump_stack 2025-06-03 21:55 ` Ian Rogers @ 2025-06-11 22:05 ` Ian Rogers 0 siblings, 0 replies; 7+ messages in thread From: Ian Rogers @ 2025-06-11 22:05 UTC (permalink / raw) To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra, Ingo Molnar, Namhyung Kim, Mark Rutland, Alexander Shishkin, Jiri Olsa, Adrian Hunter, Kan Liang, James Clark, Howard Chu, Yicong Yang, Michael Petlan, Andi Kleen, Christophe Leroy, Dr. David Alan Gilbert, Krzysztof Łopatowski, Dmitry Vyukov, linux-perf-users, linux-kernel On Tue, Jun 3, 2025 at 2:55 PM Ian Rogers <irogers@google.com> wrote: > > On Mon, Jun 2, 2025 at 10:32 AM Ian Rogers <irogers@google.com> wrote: > > > > On Thu, May 29, 2025 at 3:02 PM Ian Rogers <irogers@google.com> wrote: > > > > > > On Thu, May 29, 2025 at 1:21 PM Arnaldo Carvalho de Melo > > > <acme@kernel.org> wrote: > > > > > > > > On Wed, May 28, 2025 at 10:23:22PM -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: > > > > > > > > So you are testing it with: > > > > > > > > root@number:~# perf test PERF_RECORD > > > > 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 : Skip (permissions) > > > > root@number:~# > > > > > > > > ? > > > > > > You are running the test as a child and by default the child test > > > output is only displayed if verbose is enabled. I use verbose=2 below > > > as verbose=1 won't display anything unless the child test gives a fail > > > exit value: > > > ``` > > > $ git log --oneline > > > b9ac06abfde9 perf debug: Add function symbols to dump_stack > > > e561806265ed perf machine: Factor creating a "live" machine out of dwarf-unwind > > > 628e124404b3 perf tests switch-tracking: Fix timestamp comparison > > > $ make -C tools/perf O=/tmp/perf > > > ... > > > $ sudo /tmp/perf/perf test -vv PERF_RECORD > > > 8: PERF_RECORD_* events & perf_sample fields: > > > 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 0x5617ec45e5e3 in child_test_sig_handler builtin-test.c:0 > > > #1 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > > > #2 0x7f855c699687 in __internal_syscall_cancel cancellation.c:64 > > > #3 0x7f855c6e5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72 > > > #4 0x7f855c6f1393 in __nanosleep nanosleep.c:26 > > > #5 0x7f855c702d68 in __sleep sleep.c:55 > > > #6 0x5617ec46ebfb in test__PERF_RECORD perf-record.c:0 > > > #7 0x5617ec45e4f0 in run_test_child builtin-test.c:0 > > > #8 0x5617ec3faf0d in start_command run-command.c:127 > > > #9 0x5617ec45f433 in __cmd_test builtin-test.c:0 > > > #10 0x5617ec45faff in cmd_test perf[147aff] > > > #11 0x5617ec3ed960 in run_builtin perf.c:0 > > > #12 0x5617ec3edc7b in handle_internal_command perf.c:0 > > > #13 0x5617ec368d33 in main perf[50d33] > > > #14 0x7f855c633ca8 in __libc_start_call_main libc_start_call_main.h:74 > > > #15 0x7f855c633d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > > > #16 0x5617ec369381 in _start perf[51381] > > > > > > ---- unexpected signal (2) ---- > > > #0 0x5617ec45e5e3 in child_test_sig_handler builtin-test.c:0 > > > #1 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > > > #2 0x7f855c6a3a14 in pthread_sigmask@GLIBC_2.2.5 pthread_sigmask.c:45 > > > #3 0x7f855c649fd9 in __GI___sigprocmask sigprocmask.c:26 > > > #4 0x7f855c72601b in __longjmp_chk longjmp.c:36 > > > #5 0x5617ec45e600 in print_test_result.isra.0 builtin-test.c:0 > > > #6 0x7f855c649df0 in __restore_rt libc_sigaction.c:0 > > > #7 0x7f855c699687 in __internal_syscall_cancel cancellation.c:64 > > > #8 0x7f855c6e5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72 > > > #9 0x7f855c6f1393 in __nanosleep nanosleep.c:26 > > > #10 0x7f855c702d68 in __sleep sleep.c:55 > > > #11 0x5617ec46ebfb in test__PERF_RECORD perf-record.c:0 > > > #12 0x5617ec45e4f0 in run_test_child builtin-test.c:0 > > > #13 0x5617ec3faf0d in start_command run-command.c:127 > > > #14 0x5617ec45f433 in __cmd_test builtin-test.c:0 > > > #15 0x5617ec45faff in cmd_test perf[147aff] > > > #16 0x5617ec3ed960 in run_builtin perf.c:0 > > > #17 0x5617ec3edc7b in handle_internal_command perf.c:0 > > > #18 0x5617ec368d33 in main perf[50d33] > > > #19 0x7f855c633ca8 in __libc_start_call_main libc_start_call_main.h:74 > > > #20 0x7f855c633d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > > > #21 0x5617ec369381 in _start perf[51381] > > > 8: PERF_RECORD_* events & perf_sample fields : > > > Skip (permissions) > > > ``` > > > > > > > > > > I built it with DEBUG=1 and without, and with your patch, following your > > > > example output, I'm not being able to reproduce. > > > > > > > > Tried it as well with: > > > > > > > > ⬢ [acme@toolbx perf-tools-next]$ cat segv.patch > > > > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > > > > index 8b30c6f16a9eeac1..e55d86f1097d6d79 100644 > > > > --- a/tools/perf/util/symbol.c > > > > +++ b/tools/perf/util/symbol.c > > > > @@ -402,6 +402,8 @@ static struct symbol *symbols__find(struct rb_root_cached *symbols, u64 ip) > > > > { > > > > struct rb_node *n; > > > > > > > > + *(int *)NULL = 0; > > > > + > > > > if (symbols == NULL) > > > > return NULL; > > > > > > > > ⬢ [acme@toolbx perf-tools-next]$ patch -p1 < segv.patch > > > > patching file tools/perf/util/symbol.c > > > > ⬢ [acme@toolbx perf-tools-next]$ m > > > > rm: cannot remove '/home/acme/libexec/perf-core/scripts/python/Perf-Trace-Util/lib/Perf/Trace/__pycache__/Core.cpython-313.pyc': Permission denied > > > > make: Entering directory '/home/acme/git/perf-tools-next/tools/perf' > > > > BUILD: Doing 'make -j32' parallel build > > > > Warning: Kernel ABI header differences: > > > > diff -u tools/arch/arm64/include/asm/cputype.h arch/arm64/include/asm/cputype.h > > > > > > > > Auto-detecting system features: > > > > ... libdw: [ on ] > > > > ... glibc: [ on ] > > > > ... libelf: [ on ] > > > > ... libnuma: [ on ] > > > > ... numa_num_possible_cpus: [ on ] > > > > ... libperl: [ on ] > > > > ... libpython: [ on ] > > > > ... libcrypto: [ on ] > > > > ... libcapstone: [ on ] > > > > ... llvm-perf: [ on ] > > > > ... zlib: [ on ] > > > > ... lzma: [ on ] > > > > ... get_cpuid: [ on ] > > > > ... bpf: [ on ] > > > > ... libaio: [ on ] > > > > ... libzstd: [ on ] > > > > > > > > INSTALL libsubcmd_headers > > > > INSTALL libperf_headers > > > > INSTALL libapi_headers > > > > INSTALL libsymbol_headers > > > > INSTALL libbpf_headers > > > > CC /tmp/build/perf-tools-next/util/symbol.o > > > > LD /tmp/build/perf-tools-next/util/perf-util-in.o > > > > LD /tmp/build/perf-tools-next/perf-util-in.o > > > > AR /tmp/build/perf-tools-next/libperf-util.a > > > > LINK /tmp/build/perf-tools-next/perf > > > > GEN /tmp/build/perf-tools-next/python/perf.cpython-313-x86_64-linux-gnu.so > > > > INSTALL binaries > > > > INSTALL tests > > > > INSTALL libperf-jvmti.so > > > > INSTALL libexec > > > > INSTALL perf-archive > > > > INSTALL perf-iostat > > > > INSTALL perl-scripts > > > > INSTALL python-scripts > > > > INSTALL dlfilters > > > > INSTALL perf_completion-script > > > > INSTALL perf-tip > > > > make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf' > > > > 18: 'import perf' in python : Ok > > > > ⬢ [acme@toolbx perf-tools-next]$ > > > > > > > > root@number:~# perf top > > > > perf: Segmentation fault > > > > -------- backtrace -------- > > > > Segmentation fault (core dumped) > > > > root@number:~# > > > > > > > > Tried also with this, but probably something else is at play: > > > > > > > > root@number:~# perf probe -x ~/bin/perf dump_stack > > > > Added new event: > > > > probe_perf:dump_stack (on dump_stack in /home/acme/bin/perf) > > > > > > > > You can now use it in all perf tools, such as: > > > > > > > > perf record -e probe_perf:dump_stack -aR sleep 1 > > > > > > > > root@number:~# > > > > root@number:~# perf trace -e probe_perf:dump_stack/max-stack=16/ perf top > > > > perf: Segmentation fault > > > > -------- backtrace -------- > > > > root@number:~# > > > > > > > > Running perf trace on a separate terminal it also doesn't catch > > > > dump_stack being called (that probe point). > > > > > > > > root@number:~# perf top --stdio > > > > PerfTop: 0 irqs/sec kernel: 0.0% exact: 0.0% lost: 0/0 drop: 0/0 [4000Hz cycles:P], (all, 32 CPUs) > > > > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ > > > > > > > > perf: Segmentation fault > > > > Segmentation fault (core dumped) > > > > root@number:~# > > > > > > > > root@number:~# nm ~/bin/perf | grep dump_stack > > > > 0000000000637eaa T __dump_stack > > > > 00000000006380fa T dump_stack > > > > 000000000063816b T sighandler_dump_stack > > > > root@number:~# > > > > > > > > ⬢ [acme@toolbx perf-tools-next]$ rpm -q glibc > > > > glibc-2.41-5.fc42.x86_64 > > > > root@number:~# uname -a > > > > Linux number 6.14.8-300.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Thu May 22 19:26:02 UTC 2025 x86_64 GNU/Linux > > > > root@number:~# > > > > > > > > What am I missing? > > > > > > For perf top I can do: > > > ``` > > > $ sudo /tmp/perf/perf top > > > ``` > > > in a different terminal: > > > ``` > > > $ sudo killall -11 perf > > > ``` > > > then back in the first terminal: > > > ``` > > > perf: Segmentation fault > > > -------- backtrace -------- > > > #0 0x55ee68647918 in ui__signal_backtrace setup.c:110 > > > #1 0x7fe2d3849df0 in __restore_rt libc_sigaction.c:0 > > > #2 0x7fe2d38a49ee in __syscall_cancel_arch syscall_cancel.S:56 > > > #3 0x7fe2d3899668 in __internal_syscall_cancel cancellation.c:54 > > > #4 0x7fe2d38996ad in __syscall_cancel cancellation.c:79 > > > #5 0x7fe2d390d9c6 in __poll poll.c:43 > > > #6 0x55ee6855dfcb in fdarray__poll array.c:139 > > > #7 0x55ee68565a05 in perf_evlist__poll evlist.c:391 > > > #8 0x55ee68673b5a in evlist__poll evlist.c:594 > > > #9 0x55ee684e7a61 in __cmd_top builtin-top.c:1369 > > > #10 0x55ee684e9a6c in cmd_top builtin-top.c:1856 > > > #11 0x55ee6855d1f0 in run_builtin perf.c:351 > > > #12 0x55ee6855d497 in handle_internal_command perf.c:404 > > > #13 0x55ee6855d5f0 in run_argv perf.c:451 > > > #14 0x55ee6855d939 in main perf.c:558 > > > #15 0x7fe2d3833ca8 in __libc_start_call_main libc_start_call_main.h:74 > > > #16 0x7fe2d3833d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128 > > > #17 0x55ee684b0a91 in _start perf[4ca91] > > > ``` > > > As the same symbol code is used for the backtrace then adding the segv > > > there is likely causing a segv in the signal handler in __dump_stack. > > > > Just to note, it would be nice for this to land as I need to rebase: > > https://lore.kernel.org/lkml/20250529044000.759937-19-irogers@google.com/ > > due to the machine changes. I believe the patches are WAI as shown in > > the output. > > Ok, I see this made it into v6.16 PR: > https://lore.kernel.org/lkml/20250603203501.1961487-1-acme@kernel.org/ Actually just the first patch. I'll rebase and resend just patch 2 as v3. Thanks, Ian ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2025-06-11 22:05 UTC | newest] Thread overview: 7+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2025-05-29 5:23 [PATCH v2 1/2] perf machine: Factor creating a "live" machine out of dwarf-unwind Ian Rogers 2025-05-29 5:23 ` [PATCH v2 2/2] perf debug: Add function symbols to dump_stack Ian Rogers 2025-05-29 20:21 ` Arnaldo Carvalho de Melo 2025-05-29 22:02 ` Ian Rogers 2025-06-02 17:32 ` Ian Rogers 2025-06-03 21:55 ` Ian Rogers 2025-06-11 22:05 ` Ian Rogers
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