Messages in this thread | | | From | Song Liu <> | Subject | Re: [PATCH v2 2/2] perf-stat: enable counting events for BPF programs | Date | Tue, 8 Dec 2020 18:16:25 +0000 |
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> On Dec 8, 2020, at 2:24 AM, Jiri Olsa <jolsa@redhat.com> wrote: > > On Tue, Dec 08, 2020 at 01:36:57AM +0000, Song Liu wrote: > > SNIP > >>> >>> I'm still getting >>> >>> [root@dell-r440-01 perf]# ./perf stat -b 38 >>> libbpf: elf: skipping unrecognized data section(9) .eh_frame >>> libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9) .eh_frame >>> libbpf: XXX is not found in vmlinux BTF >>> libbpf: failed to load object 'bpf_prog_profiler_bpf' >>> libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2 >>> ... >>> >>> with id 38 being: >>> >>> 38: tracepoint name sys_enter tag 03418b72a610af75 gpl >>> loaded_at 2020-12-07T22:54:05+0100 uid 0 >>> xlated 272B jited 153B memlock 4096B map_ids 1 >>> >>> how is this supposed to work when there's XXX in the >>> program's section? libbpf is trying to find XXX in >>> kernel BTF and fails of course >> >> I think this is because this program doesn't have BTF. The actual failed >> function was bpf_program__set_attach_target(). So the error message above >> should be "Failed to _open_ bpf skeleton". I will fix the error messages. > > ah right, it's bpftrace program, so there's no BTF loaded for the program > I'll check if there's a way to add it, it'd be shame not to have this > feature for bpftrace programs > > there's no way around it, right? we need btf id of the program to attach > fentry/fexit to it
Yes, we do need BTF here (in bpf_program__set_attach_target). > > I think we need to fail the function if there's error detected, > and also check on the prog_name and fail if it's not found > > plus change all those pr_debug to pr_err in bpf_program_profiler_load_one
I fixed these in the next version.
Thanks, Song
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