>From: Namhyung Kim [mailto:[email protected]] > >Backtrace is a crucial info for debugging. And upcoming refcnt >tracking facility also wants to use it. > >So instead of relying on glibc's backtrace_symbols[_fd] which misses >some (static) functions , use our own symbol searching mechanism. To >do that, add perf_thread global variable to keep its maps and symbols.
Hmm, I doubt that this can work for debugging situation, because sometimes backtrace facilities has to debug itself by itself. For the some (static) functions, I'd rather like to use glibc's backtrace_symbols and addr2line or even with raw address for reliability... Thank you, > >The backtrace output from TUI is changed like below. (I made a key >action to generate a segfault for testing): > >Before: > perf: Segmentation fault > -------- backtrace -------- > perf[0x544a8b] > /usr/lib/libc.so.6(+0x33680)[0x7fc46420b680] > perf[0x54041b] > perf(perf_evlist__tui_browse_hists+0x91)[0x5432e1] > perf(cmd_report+0x1d20)[0x43cb10] > perf[0x487073] > perf(main+0x62f)[0x42cb1f] > /usr/lib/libc.so.6(__libc_start_main+0xf0)[0x7fc4641f8610] > perf(_start+0x29)[0x42cc39] > [0x0] > >After: > perf: Segmentation fault > -------- backtrace -------- > perf_evsel__hists_browse(+0x43b) in perf [0x54066b] > perf_evlist__tui_browse_hists(+0x91) in perf [0x543531] > cmd_report(+0x1d20) in perf [0x43cb50] > run_builtin(+0x53) in perf [0x4870b3] > main(+0x634) in perf [0x42cb54] > __libc_start_main(+0xf0) in libc-2.22.so [0x7fea3577c610] > _start(+0x29) in perf [0x42cc79] > [0x0] > >Cc: Frederic Weisbecker <[email protected]> >Cc: Masami Hiramatsu <[email protected]> >Signed-off-by: Namhyung Kim <[email protected]> >--- > tools/perf/perf.c | 7 +++++- > tools/perf/ui/tui/setup.c | 21 ++++++++++++++-- > tools/perf/util/util.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++ > tools/perf/util/util.h | 5 ++++ > 4 files changed, 92 insertions(+), 3 deletions(-) > >diff --git a/tools/perf/perf.c b/tools/perf/perf.c >index 4bee53c3f796..f77eb440b05c 100644 >--- a/tools/perf/perf.c >+++ b/tools/perf/perf.c >@@ -604,6 +604,8 @@ int main(int argc, const char **argv) > */ > pthread__block_sigwinch(); > >+ create_perf_thread(); >+ > while (1) { > static int done_help; > int was_alias = run_argv(&argc, &argv); >@@ -615,7 +617,7 @@ int main(int argc, const char **argv) > fprintf(stderr, "Expansion of alias '%s' failed; " > "'%s' is not a perf-command\n", > cmd, argv[0]); >- goto out; >+ goto out_destroy; > } > if (!done_help) { > cmd = argv[0] = help_unknown_cmd(cmd); >@@ -626,6 +628,9 @@ int main(int argc, const char **argv) > > fprintf(stderr, "Failed to run command '%s': %s\n", > cmd, strerror_r(errno, sbuf, sizeof(sbuf))); >+ >+out_destroy: >+ destroy_perf_thread(); > out: > return 1; > } >diff --git a/tools/perf/ui/tui/setup.c b/tools/perf/ui/tui/setup.c >index 7dfeba0a91f3..bc2da884e65a 100644 >--- a/tools/perf/ui/tui/setup.c >+++ b/tools/perf/ui/tui/setup.c >@@ -13,6 +13,8 @@ > #include "../libslang.h" > #include "../keysyms.h" > #include "tui.h" >+#include "../../util/symbol.h" >+#include "../../util/thread.h" > > static volatile int ui__need_resize; > >@@ -96,14 +98,29 @@ int ui__getch(int delay_secs) > static void ui__signal_backtrace(int sig) > { > void *stackdump[32]; >- size_t size; >+ size_t size, i; > > ui__exit(false); > psignal(sig, "perf"); > > printf("-------- backtrace --------\n"); > size = backtrace(stackdump, ARRAY_SIZE(stackdump)); >- backtrace_symbols_fd(stackdump, size, STDOUT_FILENO); >+ /* skip first two stack frame (for this function and signal stack) */ >+ for (i = 2; i < size; i++) { >+ struct addr_location al = { >+ .sym = NULL, >+ }; >+ >+ thread__find_addr_location(perf_thread, PERF_RECORD_MISC_USER, >+ MAP__FUNCTION, (long)stackdump[i], >&al); >+ >+ if (al.sym) >+ printf("%s(+0x%"PRIx64") in ", al.sym->name, >+ map__map_ip(al.map, (u64)stackdump[i]) - >al.sym->start); >+ if (al.map) >+ printf("%s ", al.map->dso->short_name); >+ printf("[0x%lx]\n", (unsigned long)stackdump[i]); >+ } > > exit(0); > } >diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c >index 75759aebc7b8..f1a26ea14053 100644 >--- a/tools/perf/util/util.c >+++ b/tools/perf/util/util.c >@@ -16,6 +16,9 @@ > #include <linux/kernel.h> > #include <unistd.h> > #include "callchain.h" >+#include "machine.h" >+#include "thread.h" >+#include "thread_map.h" > > struct callchain_param callchain_param = { > .mode = CHAIN_GRAPH_ABS, >@@ -696,3 +699,62 @@ fetch_kernel_version(unsigned int *puint, char *str, > *puint = (version << 16) + (patchlevel << 8) + sublevel; > return 0; > } >+ >+ >+static int process_event(struct perf_tool *tool, union perf_event *event, >+ struct perf_sample *sample, struct machine *machine) >+{ >+ switch (event->header.type) { >+ case PERF_RECORD_COMM: >+ return tool->comm(tool, event, sample, machine); >+ case PERF_RECORD_MMAP: >+ return tool->mmap(tool, event, sample, machine); >+ case PERF_RECORD_MMAP2: >+ return tool->mmap2(tool, event, sample, machine); >+ default: >+ break; >+ } >+ return 0; >+} >+ >+struct thread *perf_thread; >+ >+void create_perf_thread(void) >+{ >+ struct perf_tool tool = { >+ .comm = perf_event__process_comm, >+ .mmap = perf_event__process_mmap, >+ .mmap2 = perf_event__process_mmap2, >+ }; >+ struct thread_map *tm; >+ struct machine *machine; >+ int pid = getpid(); >+ >+ machine = machine__new_host(); >+ if (machine == NULL) >+ return; >+ >+ tm = thread_map__new_dummy(); >+ if (tm == NULL) { >+ machine__delete(machine); >+ return; >+ } >+ >+ thread_map__set_pid(tm, 0, pid); >+ >+ perf_event__synthesize_thread_map(&tool, tm, process_event, machine, >+ false, 500); >+ >+ perf_thread = machine__find_thread(machine, pid, pid); >+ BUG_ON(perf_thread == NULL); >+ >+ thread_map__put(tm); >+} >+ >+void destroy_perf_thread(void) >+{ >+ struct machine *machine = perf_thread->mg->machine; >+ >+ machine__delete_threads(machine); >+ machine__delete(machine); >+} >diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h >index dcc659017976..630e145049aa 100644 >--- a/tools/perf/util/util.h >+++ b/tools/perf/util/util.h >@@ -358,4 +358,9 @@ int fetch_kernel_version(unsigned int *puint, > #define KVER_FMT "%d.%d.%d" > #define KVER_PARAM(x) KVER_VERSION(x), KVER_PATCHLEVEL(x), KVER_SUBLEVEL(x) > >+extern struct thread *perf_thread; >+ >+void create_perf_thread(void); >+void destroy_perf_thread(void); >+ > #endif /* GIT_COMPAT_UTIL_H */ >-- >2.6.2
