perf bpf: Save BTF information as headers to perf.data

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 <[email protected]>
Reviewed-by: Jiri Olsa <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stanislav Fomichev <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions