[PATCHv2 bpf-next 0/8] bpf: Fixes for kprobe multi on kernel modules

[Jiri Olsa <jolsa@kernel.org>]

hi,
Martynas reported kprobe _multi link does not resolve symbols
from kernel modules, which attach by address works.

In addition while fixing that I realized we do not take module
reference if the module has kprobe_multi link on top of it and
can be removed.

There's mo crash related to this, it will silently disappear from
ftrace tables, while kprobe_multi link stays up with no data.

This patchset has fixes for both issues.

v2 changes:
  - added acks (Song)
  - added comment to kallsyms_callback (Song)
  - change module_callback realloc logic (Andrii)
  - get rid of macros in tests (Andrii)

thanks,
jirka


---
Jiri Olsa (8):
      kallsyms: Make module_kallsyms_on_each_symbol generally available
      ftrace: Add support to resolve module symbols in ftrace_lookup_symbols
      bpf: Rename __bpf_kprobe_multi_cookie_cmp to bpf_kprobe_multi_addrs_cmp
      bpf: Take module reference on kprobe_multi link
      selftests/bpf: Add load_kallsyms_refresh function
      selftests/bpf: Add bpf_testmod_fentry_* functions
      selftests/bpf: Add kprobe_multi check to module attach test
      selftests/bpf: Add kprobe_multi kmod attach api tests

 include/linux/module.h                                             |  9 ++++++++
 kernel/module/kallsyms.c                                           |  2 --
 kernel/trace/bpf_trace.c                                           | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 kernel/trace/ftrace.c                                              | 16 +++++++++-----
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c              | 24 +++++++++++++++++++++
 tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/prog_tests/module_attach.c             |  7 +++++++
 tools/testing/selftests/bpf/progs/kprobe_multi.c                   | 50 +++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/test_module_attach.c             |  6 ++++++
 tools/testing/selftests/bpf/trace_helpers.c                        | 20 +++++++++++-------
 tools/testing/selftests/bpf/trace_helpers.h                        |  2 ++
 11 files changed, 306 insertions(+), 17 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c