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bpf: Separate bpf_get_[stack|stackid] for perf events BPF

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Calling get_perf_callchain() on perf_events from PEBS entries may cause
unwinder errors. To fix this issue, the callchain is fetched early. Such
perf_events are marked with __PERF_SAMPLE_CALLCHAIN_EARLY.

Similarly, calling bpf_get_[stack|stackid] on perf_events from PEBS may
also cause unwinder errors. To fix this, add separate version of these
two helpers, bpf_get_[stack|stackid]_pe. These two hepers use callchain in
bpf_perf_event_data_kern->data->callchain.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200723180648.1429892-2-songliubraving@fb.com
This commit is contained in:
Song Liu
2020-07-23 11:06:44 -07:00
committed by Alexei Starovoitov
parent 909e446b32
commit 7b04d6d60f
3 changed files with 170 additions and 20 deletions
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4
kernel/trace/bpf_trace.c
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@@ -1411,9 +1411,9 @@ pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_perf_event_output:
return &bpf_perf_event_output_proto_tp;
case BPF_FUNC_get_stackid:
return &bpf_get_stackid_proto_tp;
return &bpf_get_stackid_proto_pe;
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_tp;
return &bpf_get_stack_proto_pe;
case BPF_FUNC_perf_prog_read_value:
return &bpf_perf_prog_read_value_proto;
case BPF_FUNC_read_branch_records: