Messages in this thread Patch in this message | | | From | Kajol Jain <> | Subject | [PATCH] bpf: Enable bpf support for reading branch records in powerpc | Date | Mon, 15 Nov 2021 10:14:37 +0530 |
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Branch data available to bpf programs can be very useful to get stack traces out of userspace applications.
Commit fff7b64355ea ("bpf: Add bpf_read_branch_records() helper") added bpf support to capture branch records in x86. Enable this feature for powerpc as well.
Commit 67306f84ca78 ("selftests/bpf: Add bpf_read_branch_records() selftest") adds selftest corresponding to bpf branch read function bpf_read_branch_records(). Used this selftest to test bpf support, for reading branch records in powerpc.
Selftest result in power9 box before this patch changes:
[command]# ./test_progs -t perf_branches Failed to load bpf_testmod.ko into the kernel: -8 WARNING! Selftests relying on bpf_testmod.ko will be skipped. test_perf_branches_common:PASS:test_perf_branches_load 0 nsec test_perf_branches_common:PASS:attach_perf_event 0 nsec test_perf_branches_common:PASS:set_affinity 0 nsec check_good_sample:PASS:output not valid 0 nsec check_good_sample:FAIL:read_branches_size err -2 check_good_sample:FAIL:read_branches_stack err -2 check_good_sample:FAIL:read_branches_stack stack bytes written=-2 not multiple of struct size=24 check_good_sample:FAIL:read_branches_global err -2 check_good_sample:FAIL:read_branches_global global bytes written=-2 not multiple of struct size=24 check_good_sample:PASS:read_branches_size 0 nsec #75/1 perf_branches_hw:FAIL #75/2 perf_branches_no_hw:OK #75 perf_branches:FAIL Summary: 0/1 PASSED, 0 SKIPPED, 2 FAILED
Selftest result in power9 box after this patch changes:
[command]#: ./test_progs -t perf_branches #75/1 perf_branches_hw:OK #75/2 perf_branches_no_hw:OK #75 perf_branches:OK Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: Kajol Jain<kjain@linux.ibm.com> --- kernel/trace/bpf_trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index fdd14072fc3b..2b7343b64bb7 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1245,7 +1245,7 @@ static const struct bpf_func_proto bpf_perf_prog_read_value_proto = { BPF_CALL_4(bpf_read_branch_records, struct bpf_perf_event_data_kern *, ctx, void *, buf, u32, size, u64, flags) { -#ifndef CONFIG_X86 +#if !(defined(CONFIG_X86) || defined(CONFIG_PPC64)) return -ENOENT; #else static const u32 br_entry_size = sizeof(struct perf_branch_entry); -- 2.27.0
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