Hi, Adrian Hunter <adrian.hun...@intel.com> writes:
> On 18/10/18 1:55 AM, Arnaldo Carvalho de Melo wrote: >> From: Arnaldo Carvalho de Melo <a...@redhat.com> >> >> David reports that: >> >> <quote> >> Perf has this hack where it uses the kernel symbol map as a backup when >> a symbol can't be found in the user's symbol table(s). > > I don't think this is a complete fix because it exposes new problems. This commit broke function name resolution for 'perf record -g' for me. What I mean is, with this commit applied: $ ./tools/perf/perf record -g -- sleep 1 $ ./tools/perf/perf report 'perf report' doesn't seem to be able to show the function names of the trace. If I revert this commit, function names are resolved fine. > This code caters for branches from kernel space to user space and vice > versa. That is, since there is only one cpumode so it is certain to be > wrong for either 'ip' or 'addr' when they are not both in the kernel > or both in userspace. > >> >> >> Cc: Adrian Hunter <adrian.hun...@intel.com> >> Cc: David Ahern <dsah...@gmail.com> >> Cc: Jiri Olsa <jo...@kernel.org> >> Cc: Namhyung Kim <namhy...@kernel.org> >> Cc: Wang Nan <wangn...@huawei.com> >> Link: https://lkml.kernel.org/n/tip-cs7skq9pp0kjypiju6o7t...@git.kernel.org >> Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> >> --- >> tools/perf/util/event.c | 21 ++------------------- >> 1 file changed, 2 insertions(+), 19 deletions(-) >> >> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c >> index 0988eb3b844b..bc646185f8d9 100644 >> --- a/tools/perf/util/event.c >> +++ b/tools/perf/util/event.c >> @@ -1561,26 +1561,9 @@ struct map *thread__find_map(struct thread *thread, >> u8 cpumode, u64 addr, >> >> return NULL; >> } >> -try_again: >> + >> al->map = map_groups__find(mg, al->addr); >> - if (al->map == NULL) { >> - /* >> - * If this is outside of all known maps, and is a negative >> - * address, try to look it up in the kernel dso, as it might be >> - * a vsyscall or vdso (which executes in user-mode). >> - * >> - * XXX This is nasty, we should have a symbol list in the >> - * "[vdso]" dso, but for now lets use the old trick of looking >> - * in the whole kernel symbol list. >> - */ >> - if (cpumode == PERF_RECORD_MISC_USER && machine && >> - mg != &machine->kmaps && >> - machine__kernel_ip(machine, al->addr)) { >> - mg = &machine->kmaps; >> - load_map = true; >> - goto try_again; >> - } >> - } else { >> + if (al->map != NULL) { >> /* >> * Kernel maps might be changed when loading symbols so loading >> * must be done prior to using kernel maps. >> -- Vinicius
