[PATCH v2 bpf-next 0/7] libbpf: add tracing attach APIs

[Andrii Nakryiko <andriin@fb.com>]

This patchset adds the following APIs to allow attaching BPF programs to
tracing entities:
- bpf_program__attach_perf_event for attaching to any opened perf event FD,
  allowing users full control;
- bpf_program__attach_kprobe for attaching to kernel probes (both entry and
  return probes);
- bpf_program__attach_uprobe for attaching to user probes (both entry/return);
- bpf_program__attach_tracepoint for attaching to kernel tracepoints;
- bpf_program__attach_raw_tracepoint for attaching to raw kernel tracepoint
  (wrapper around bpf_raw_tracepoint_open);

This set of APIs makes libbpf more useful for tracing applications.

Pre-patch #1 makes internal libbpf_strerror_r helper function work w/ negative
error codes, lifting the burder off callers to keep track of error sign.
Patch #2 adds attach_perf_event, which is the base for all other APIs.
Patch #3 adds kprobe/uprobe APIs.
Patch #4 adds tracepoint/raw_tracepoint APIs.
Patch #5 converts one existing test to use attach_perf_event.
Patch #6 adds new kprobe/uprobe tests.
Patch #7 converts all the selftests currently using tracepoint to new APIs.

v1->v2:
- preserve errno before close() call (Stanislav);
- use libbpf_perf_event_disable_and_close in selftest (Stanislav);
- remove unnecessary memset (Stanislav);

Andrii Nakryiko (7):
  libbpf: make libbpf_strerror_r agnostic to sign of error
  libbpf: add ability to attach/detach BPF to perf event
  libbpf: add kprobe/uprobe attach API
  libbpf: add tracepoint/raw tracepoint attach API
  selftests/bpf: switch test to new attach_perf_event API
  selftests/bpf: add kprobe/uprobe selftests
  selftests/bpf: convert existing tracepoint tests to new APIs

 tools/lib/bpf/libbpf.c                        | 346 ++++++++++++++++++
 tools/lib/bpf/libbpf.h                        |  17 +
 tools/lib/bpf/libbpf.map                      |   6 +
 tools/lib/bpf/str_error.c                     |   2 +-
 .../selftests/bpf/prog_tests/attach_probe.c   | 151 ++++++++
 .../bpf/prog_tests/stacktrace_build_id.c      |  49 +--
 .../bpf/prog_tests/stacktrace_build_id_nmi.c  |  24 +-
 .../selftests/bpf/prog_tests/stacktrace_map.c |  42 +--
 .../bpf/prog_tests/stacktrace_map_raw_tp.c    |  14 +-
 .../bpf/prog_tests/task_fd_query_rawtp.c      |  10 +-
 .../bpf/prog_tests/task_fd_query_tp.c         |  51 +--
 .../bpf/prog_tests/tp_attach_query.c          |  56 +--
 .../selftests/bpf/progs/test_attach_probe.c   |  55 +++
 13 files changed, 651 insertions(+), 172 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/attach_probe.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_attach_probe.c

-- 
2.17.1