linux-kernel - [PATCH] bpf: fix sample_flags for bpf_perf_event

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Date:   Fri,  7 Oct 2022 10:13:27 +0200
From:   Sumanth Korikkar <sumanthk@...ux.ibm.com>
To:     olsajiri@...il.com
Cc:     bpf@...r.kernel.org, gor@...ux.ibm.com, hca@...ux.ibm.com,
        iii@...ux.ibm.com, linux-kernel@...r.kernel.org,
        linux-tip-commits@...r.kernel.org, namhyung@...nel.org,
        peterz@...radead.org, sumanthk@...ux.ibm.com, svens@...ux.ibm.com,
        tip-bot2@...utronix.de, tmricht@...ux.ibm.com, x86@...nel.org
Subject: [PATCH] bpf: fix sample_flags for bpf_perf_event_output

* 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@...nel.org>
Signed-off-by: Sumanth Korikkar <sumanthk@...ux.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