This patch enables 'perf record' to save BTF information as headers to
perf.data.
A new header type HEADER_BPF_BTF is introduced for this data.
Committer testing:
As root, being on the kernel sources top level directory, run:
# perf trace -e tools/perf/examples/bpf/augmented_raw_syscalls.c -e *msg
Just to compile and load a BPF program that attaches to the
raw_syscalls:sys_{enter,exit} tracepoints to trace the syscalls ending
in "msg" (recvmsg, sendmsg, recvmmsg, sendmmsg, etc).
Make sure you have a recent enough clang, say version 9, to get the
BTF ELF sections needed for this testing:
# clang --version | head -1
clang version 9.0.0 (https://git.llvm.org/git/clang.git/ 7906282d3afec5dfdc2b27943fd6c0309086c507) (https://git.llvm.org/git/llvm.git/ a1b5de1ff8ae8bc79dc8e86e1f82565229bd0500)
# readelf -SW tools/perf/examples/bpf/augmented_raw_syscalls.o | grep BTF
[22] .BTF PROGBITS 0000000000000000 000ede 000b0e 00 0 0 1
[23] .BTF.ext PROGBITS 0000000000000000 0019ec 0002a0 00 0 0 1
[24] .rel.BTF.ext REL 0000000000000000 002fa8 000270 10 30 23 8
Then do a systemwide perf record session for a few seconds:
# perf record -a sleep 2s
Then look at:
# perf report --header-only | grep b[pt]f
# event : name = cycles:ppp, , id = { 1116204, 1116205, 1116206, 1116207, 1116208, 1116209, 1116210, 1116211 }, size = 112, { sample_period, sample_freq } = 4000, sample_type = IP|TID|TIME|PERIOD, read_format = ID, disabled = 1, inherit = 1, mmap = 1, comm = 1, freq = 1, enable_on_exec = 1, task = 1, precise_ip = 3, sample_id_all = 1, exclude_guest = 1, mmap2 = 1, comm_exec = 1, ksymbol = 1, bpf_event = 1
# bpf_prog_info of id 13
# bpf_prog_info of id 14
# bpf_prog_info of id 15
# bpf_prog_info of id 16
# bpf_prog_info of id 17
# bpf_prog_info of id 18
# bpf_prog_info of id 21
# bpf_prog_info of id 22
# bpf_prog_info of id 51
# bpf_prog_info of id 52
# btf info of id 8
#
We need to show more info about these BPF and BTF entries , but that can
be done later.
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/20190312053051.2690567-10-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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