[PATCHv3 bpf-next 0/5] bpf: Speed up symbol resolving in kprobe multi link

[Jiri Olsa <jolsa@kernel.org>]

hi,
sending additional fix for symbol resolving in kprobe multi link
requested by Alexei and Andrii [1].

This speeds up bpftrace kprobe attachment, when using pure symbols
(3344 symbols) to attach:

Before:

  # perf stat -r 5 -e cycles ./src/bpftrace -e 'kprobe:x* {  } i:ms:1 { exit(); }'
  ...
  6.5681 +- 0.0225 seconds time elapsed  ( +-  0.34% )

After:

  # perf stat -r 5 -e cycles ./src/bpftrace -e 'kprobe:x* {  } i:ms:1 { exit(); }'
  ...
  0.5661 +- 0.0275 seconds time elapsed  ( +-  4.85% )

v3 changes:
  - renamed kallsyms_lookup_names to ftrace_lookup_symbols
    and moved it to ftrace.c [Masami]
  - added ack [Andrii]
  - couple small test fixes [Andrii]

v2 changes (first version [2]):
  - removed the 2 seconds check [Alexei]
  - moving/forcing symbols sorting out of kallsyms_lookup_names function [Alexei]
  - skipping one array allocation and copy_from_user [Andrii]
  - several small fixes [Masami,Andrii]
  - build fix [kernel test robot]

thanks,
jirka


[1] https://lore.kernel.org/bpf/CAEf4BzZtQaiUxQ-sm_hH2qKPRaqGHyOfEsW96DxtBHRaKLoL3Q@mail.gmail.com/
[2] https://lore.kernel.org/bpf/20220407125224.310255-1-jolsa@kernel.org/
---
Jiri Olsa (5):
      kallsyms: Fully export kallsyms_on_each_symbol function
      ftrace: Add ftrace_lookup_symbols function
      fprobe: Resolve symbols with ftrace_lookup_symbols
      bpf: Resolve symbols with ftrace_lookup_symbols for kprobe multi link
      selftests/bpf: Add attach bench test

 include/linux/ftrace.h                                     |   6 ++++++
 include/linux/kallsyms.h                                   |   5 +++++
 kernel/kallsyms.c                                          |   3 +--
 kernel/trace/bpf_trace.c                                   | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------------------------
 kernel/trace/fprobe.c                                      |  32 ++++++++++++--------------------
 kernel/trace/ftrace.c                                      |  62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c | 133 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/kprobe_multi_empty.c     |  12 ++++++++++++
 8 files changed, 297 insertions(+), 68 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/kprobe_multi_empty.c