Messages in this thread | | | Date | Tue, 20 Oct 2020 09:11:32 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf tools: Fix crash with non-jited bpf progs |
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Em Mon, Oct 19, 2020 at 10:53:43PM +0200, Jiri Olsa escreveu: > On Fri, Oct 16, 2020 at 02:47:18PM +0300, Tommi Rantala wrote: > > The addr in PERF_RECORD_KSYMBOL events for non-jited bpf progs points to > > the bpf interpreter, ie. within kernel text section. When processing the > > unregister event, this causes unexpected removal of vmlinux_map, > > crashing perf later in cleanup: > > > > # perf record -- timeout --signal=INT 2s /usr/share/bcc/tools/execsnoop > > PCOMM PID PPID RET ARGS > > [ perf record: Woken up 1 times to write data ] > > [ perf record: Captured and wrote 0.208 MB perf.data (5155 samples) ] > > perf: tools/include/linux/refcount.h:131: refcount_sub_and_test: Assertion `!(new > val)' failed. > > Aborted (core dumped) > > > > # perf script -D|grep KSYM > > 0 0xa40 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_f958f6eb72ef5af6 > > 0 0xab0 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_8c42dee26e8cd4c2 > > 0 0xb20 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_f958f6eb72ef5af6 > > 108563691893 0x33d98 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3b0 len 0 type 1 flags 0x0 name bpf_prog_bc5697a410556fc2_syscall__execve > > 108568518458 0x34098 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3f0 len 0 type 1 flags 0x0 name bpf_prog_45e2203c2928704d_do_ret_sys_execve > > 109301967895 0x34830 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3b0 len 0 type 1 flags 0x1 name bpf_prog_bc5697a410556fc2_syscall__execve > > 109302007356 0x348b0 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3f0 len 0 type 1 flags 0x1 name bpf_prog_45e2203c2928704d_do_ret_sys_execve > > perf: tools/include/linux/refcount.h:131: refcount_sub_and_test: Assertion `!(new > val)' failed. > > > > Here the addresses match the bpf interpreter: > > > > # grep -e ffffffffa9b6b530 -e ffffffffa9b6b3b0 -e ffffffffa9b6b3f0 /proc/kallsyms > > ffffffffa9b6b3b0 t __bpf_prog_run224 > > ffffffffa9b6b3f0 t __bpf_prog_run192 > > ffffffffa9b6b530 t __bpf_prog_run32 > > > > Fix by not allowing vmlinux_map to be removed by PERF_RECORD_KSYMBOL > > unregister event. > > > > Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com> > > nice, I almost forgot about non jit mode by now ;-) > > Acked/Tested-by: Jiri Olsa <jolsa@redhat.com>
Thanks, applied.
- Arnaldo
> thanks, > jirka > > > --- > > tools/perf/util/machine.c | 11 ++++++++++- > > tools/perf/util/symbol.c | 7 +++++++ > > tools/perf/util/symbol.h | 2 ++ > > 3 files changed, 19 insertions(+), 1 deletion(-) > > > > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c > > index 85587de027a5..d93d35463c61 100644 > > --- a/tools/perf/util/machine.c > > +++ b/tools/perf/util/machine.c > > @@ -786,11 +786,20 @@ static int machine__process_ksymbol_unregister(struct machine *machine, > > union perf_event *event, > > struct perf_sample *sample __maybe_unused) > > { > > + struct symbol *sym; > > struct map *map; > > > > map = maps__find(&machine->kmaps, event->ksymbol.addr); > > - if (map) > > + if (!map) > > + return 0; > > + > > + if (map != machine->vmlinux_map) > > maps__remove(&machine->kmaps, map); > > + else { > > + sym = dso__find_symbol(map->dso, map->map_ip(map, map->start)); > > + if (sym) > > + dso__delete_symbol(map->dso, sym); > > + } > > > > return 0; > > } > > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > > index 5151a8c0b791..6bf8e74ea1d1 100644 > > --- a/tools/perf/util/symbol.c > > +++ b/tools/perf/util/symbol.c > > @@ -515,6 +515,13 @@ void dso__insert_symbol(struct dso *dso, struct symbol *sym) > > } > > } > > > > +void dso__delete_symbol(struct dso *dso, struct symbol *sym) > > +{ > > + rb_erase_cached(&sym->rb_node, &dso->symbols); > > + symbol__delete(sym); > > + dso__reset_find_symbol_cache(dso); > > +} > > + > > struct symbol *dso__find_symbol(struct dso *dso, u64 addr) > > { > > if (dso->last_find_result.addr != addr || dso->last_find_result.symbol == NULL) { > > diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h > > index 03e264a27cd3..60345691db09 100644 > > --- a/tools/perf/util/symbol.h > > +++ b/tools/perf/util/symbol.h > > @@ -130,6 +130,8 @@ int dso__load_kallsyms(struct dso *dso, const char *filename, struct map *map); > > > > void dso__insert_symbol(struct dso *dso, > > struct symbol *sym); > > +void dso__delete_symbol(struct dso *dso, > > + struct symbol *sym); > > > > struct symbol *dso__find_symbol(struct dso *dso, u64 addr); > > struct symbol *dso__find_symbol_by_name(struct dso *dso, const char *name); > > -- > > 2.26.2 > > >
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- Arnaldo
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