Messages in this thread Patch in this message | | | Date | Thu, 31 May 2012 10:45:57 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH/RFC 2/2] perf tools: Check callchain is corrupted |
| |
Em Thu, May 31, 2012 at 02:43:27PM +0900, Namhyung Kim escreveu: > We faced segmentation fault on perf top -G at very high sampling > rate due to a corrupted callchain. While the root cause was not > revealed (I failed to figure it out), this patch tries to protect > us from the segfault on such cases.
Capping the callchain lenght may even be a feature, not a consistency check, but I don't know how long, for consistency checking, we should consider too much, as there are cases of loooong callchains.
Ingo? Peter?
- Arnaldo > Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> > Signed-off-by: Namhyung Kim <namhyung.kim@lge.com> > --- > include/linux/perf_event.h | 4 ++-- > tools/perf/util/session.c | 14 +++++++++++++- > 2 files changed, 15 insertions(+), 3 deletions(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index 8adf70e9e3cc..0430ea6054ef 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -555,6 +555,8 @@ enum perf_event_type { > PERF_RECORD_MAX, /* non-ABI */ > }; > > +#define PERF_MAX_STACK_DEPTH 255 > + > enum perf_callchain_context { > PERF_CONTEXT_HV = (__u64)-32, > PERF_CONTEXT_KERNEL = (__u64)-128, > @@ -609,8 +611,6 @@ struct perf_guest_info_callbacks { > #include <linux/sysfs.h> > #include <asm/local.h> > > -#define PERF_MAX_STACK_DEPTH 255 > - > struct perf_callchain_entry { > __u64 nr; > __u64 ip[PERF_MAX_STACK_DEPTH]; > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c > index a7de2acac460..fa14e60ed459 100644 > --- a/tools/perf/util/session.c > +++ b/tools/perf/util/session.c > @@ -300,6 +300,11 @@ int machine__resolve_callchain(struct machine *self, > > callchain_cursor_reset(&callchain_cursor); > > + if (chain->nr > PERF_MAX_STACK_DEPTH) { > + pr_warning("corrupted callchain. skipping...\n"); > + return 0; > + } > + > for (i = 0; i < chain->nr; i++) { > u64 ip; > struct addr_location al; > @@ -318,7 +323,14 @@ int machine__resolve_callchain(struct machine *self, > case PERF_CONTEXT_USER: > cpumode = PERF_RECORD_MISC_USER; break; > default: > - break; > + pr_debug("invalid callchain context: " > + "%"PRId64"\n", (s64) ip); > + /* > + * It seems the callchain is corrupted. > + * Discard all. > + */ > + callchain_cursor_reset(&callchain_cursor); > + return 0; > } > continue; > } > -- > 1.7.10.1
| |