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authorTommi Rantala <tommi.t.rantala@nokia.com>2020-10-16 14:47:18 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2020-11-03 08:30:34 -0300
commitab8bf5f2e0321f254590ad81c6e230185d88b4e5 (patch)
tree67175e4dedde06e30bf1fa4e764e02378c159cec /tools/perf
parent263e452eff397b370e39d464c8cbd30f6bd59fb9 (diff)
downloadlwn-ab8bf5f2e0321f254590ad81c6e230185d88b4e5.tar.gz
lwn-ab8bf5f2e0321f254590ad81c6e230185d88b4e5.zip
perf tools: Fix crash with non-jited bpf progs
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> Acked-by: Jiri Olsa <jolsa@redhat.com> Tested-by: Jiri Olsa <jolsa@redhat.com> Link: https://lore.kernel.org/r/20201016114718.54332-1-tommi.t.rantala@nokia.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r--tools/perf/util/machine.c11
-rw-r--r--tools/perf/util/symbol.c7
-rw-r--r--tools/perf/util/symbol.h2
3 files changed, 19 insertions, 1 deletions
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 7d4194ffc5b0..15385ea00190 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 6138866665df..0d14abdf3d72 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 f4801c488def..954d6a049ee2 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -131,6 +131,8 @@ 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);