Messages in this thread | | | From | SeongJae Park <> | Subject | Re: [PATCH] bpf: fix sample_flags for bpf_perf_event_output | Date | Mon, 17 Oct 2022 19:27:44 +0000 |
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Hello,
The commit that this patch is fixing[1] also causes yet another segfault for 'perf-script' of tracepoint records. For example:
$ sudo timeout 3 perf record -e exceptions:page_fault_user [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.228 MB perf.data (74 samples) ] $ sudo perf script Segmentation fault
Reverting this patch and the original bug commit[1] fixes the issue. I haven't deep dive yet because I'm not familiar with this area. Anybody has any idea about this?
[1] 838d9bb62d13 ("perf: Use sample_flags for raw_data")
Thanks, SJ
On Fri, 7 Oct 2022 10:13:27 +0200 Sumanth Korikkar <sumanthk@linux.ibm.com> wrote:
> * Raw data is also filled by bpf_perf_event_output. > * Add sample_flags to indicate raw data. > * This eliminates the segfaults as shown below: > Run ./samples/bpf/trace_output > BUG pid 9 cookie 1001000000004 sized 4 > BUG pid 9 cookie 1001000000004 sized 4 > BUG pid 9 cookie 1001000000004 sized 4 > Segmentation fault (core dumped) > > Fixes: 838d9bb62d13 ("perf: Use sample_flags for raw_data") > Acked-by: Namhyung Kim <namhyung@kernel.org> > Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com> > --- > kernel/trace/bpf_trace.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 49fb9ec8366d..1ed08967fb97 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -687,6 +687,7 @@ BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map, > > perf_sample_data_init(sd, 0, 0); > sd->raw = &raw; > + sd->sample_flags |= PERF_SAMPLE_RAW; > > err = __bpf_perf_event_output(regs, map, flags, sd); > > @@ -745,6 +746,7 @@ u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, > perf_fetch_caller_regs(regs); > perf_sample_data_init(sd, 0, 0); > sd->raw = &raw; > + sd->sample_flags |= PERF_SAMPLE_RAW; > > ret = __bpf_perf_event_output(regs, map, flags, sd); > out: > -- > 2.36.1
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