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authorPeter Zijlstra <peterz@infradead.org>2018-05-10 15:48:41 +0200
committerIngo Molnar <mingo@kernel.org>2018-07-25 11:46:21 +0200
commit6cbc304f2f360f25cc8607817239d6f4a2fd3dc5 (patch)
treeba5faab5782a441ef6ba482fbfc9d2444efc4024 /kernel/events
parent4799f6856fdd38c8078a190eca3288029287cf66 (diff)
downloadlinux-6cbc304f2f360f25cc8607817239d6f4a2fd3dc5.tar.bz2
perf/x86/intel: Fix unwind errors from PEBS entries (mk-II)
Vince reported the perf_fuzzer giving various unwinder warnings and Josh reported: > Deja vu. Most of these are related to perf PEBS, similar to the > following issue: > > b8000586c90b ("perf/x86/intel: Cure bogus unwind from PEBS entries") > > This is basically the ORC version of that. setup_pebs_sample_data() is > assembling a franken-pt_regs which ORC isn't happy about. RIP is > inconsistent with some of the other registers (like RSP and RBP). And where the previous unwinder only needed BP,SP ORC also requires IP. But we cannot spoof IP because then the sample will get displaced, entirely negating the point of PEBS. So cure the whole thing differently by doing the unwind early; this does however require a means to communicate we did the unwind early. We (ab)use an unused sample_type bit for this, which we set on events that fill out the data->callchain before the normal perf_prepare_sample(). Debugged-by: Josh Poimboeuf <jpoimboe@redhat.com> Reported-by: Vince Weaver <vincent.weaver@maine.edu> Tested-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8f0434a9951a..cdb32cf8e33c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6343,7 +6343,7 @@ static u64 perf_virt_to_phys(u64 virt)
static struct perf_callchain_entry __empty_callchain = { .nr = 0, };
-static struct perf_callchain_entry *
+struct perf_callchain_entry *
perf_callchain(struct perf_event *event, struct pt_regs *regs)
{
bool kernel = !event->attr.exclude_callchain_kernel;
@@ -6382,7 +6382,9 @@ void perf_prepare_sample(struct perf_event_header *header,
if (sample_type & PERF_SAMPLE_CALLCHAIN) {
int size = 1;
- data->callchain = perf_callchain(event, regs);
+ if (!(sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
+ data->callchain = perf_callchain(event, regs);
+
size += data->callchain->nr;
header->size += size * sizeof(u64);