bpf: tracing_multi link

hi,
adding tracing_multi link support that allows fast attachment
of tracing program to many functions.

RFC: https://lore.kernel.org/bpf/20260203093819.2105105-1-jols...
v1: https://lore.kernel.org/bpf/20260220100649.628307-1-jolsa...
v2: https://lore.kernel.org/bpf/20260304222141.497203-1-jolsa...
v3: https://lore.kernel.org/bpf/20260316075138.465430-1-jolsa...

v4 changes:
- unlink rollback fix (added ftrace_hash_count) [bot]
- use const for some bpf_link_create_opts tracing_multi members [bot]
- adding missing comment for lockdep keys [bot]
- selftest error path fixes (leaks) and other assorted test fixes [Leon Hwang]
- several compile fixes wrt CONFIG_BPF_SYSCALL and CONFIG_BPF_JIT [kernel test robot]
- make ftrace_hash_clear global, because it's needed in rollback

v3 changes:
- fix module parsing [Leon Hwang]
- use function traceable check from libbpf [Leon Hwang]
- use ptr_to_u64 and fix/updated few comments [ci]
- display cookies as decimal numbers [ci]
- added link_create.flags check [ci]
- fix error path in bpf_trampoline_multi_detach [ci]
- make fentry/fexit.multi not extendable [ci]
- add missing OPTS_VALID to bpf_program__attach_tracing_multi [ci]

v2 changes:
- allocate data.unreg in bpf_trampoline_multi_attach for rollback path [ci]
  and fixed link count setup in rollback path [ci]
- several small assorted fixes [ci]
- added loongarch and powerpc changes for struct bpf_tramp_node change
- added support to attach functions from modules
- added tests for sleepable programs
- added rollback tests

v1 changes:
- added ftrace_hash_count as wrapper for hash_count [Steven]
- added trampoline mutex pool [Andrii]
- reworked 'struct bpf_tramp_node' separatoin [Andrii]
  - the 'struct bpf_tramp_node' now holds pointer to bpf_link,
    which is similar to what we do for uprobe_multi;
    I understand it's not a fundamental change compared to previous
    version which used bpf_prog pointer instead, but I don't see better
    way of doing this.. I'm happy to discuss this further if there's
    better idea
- reworked 'struct bpf_fsession_link' based on bpf_tramp_node
- made btf__find_by_glob_kind function internal helper [Andrii]
- many small assorted fixes [Andrii,CI]
- added session support [Leon Hwang]
- added cookies support
- added more tests


Note I plan to send linkinfo support separately, the patchset is big enough.

thanks,
jirka


Cc: Hengqi Chen <hengqi.chen@gmail.com>
---
Jiri Olsa (25):
      ftrace: Add ftrace_hash_count function
      ftrace: Make ftrace_hash_clear global
      bpf: Use mutex lock pool for bpf trampolines
      bpf: Add struct bpf_trampoline_ops object
      bpf: Add struct bpf_tramp_node object
      bpf: Factor fsession link to use struct bpf_tramp_node
      bpf: Add multi tracing attach types
      bpf: Move sleepable verification code to btf_id_allow_sleepable
      bpf: Add bpf_trampoline_multi_attach/detach functions
      bpf: Add support for tracing multi link
      bpf: Add support for tracing_multi link cookies
      bpf: Add support for tracing_multi link session
      bpf: Add support for tracing_multi link fdinfo
      libbpf: Add bpf_object_cleanup_btf function
      libbpf: Add bpf_link_create support for tracing_multi link
      libbpf: Add btf_type_is_traceable_func function
      libbpf: Add support to create tracing multi link
      selftests/bpf: Add tracing multi skel/pattern/ids attach tests
      selftests/bpf: Add tracing multi skel/pattern/ids module attach tests
      selftests/bpf: Add tracing multi intersect tests
      selftests/bpf: Add tracing multi cookies test
      selftests/bpf: Add tracing multi session test
      selftests/bpf: Add tracing multi attach fails test
      selftests/bpf: Add tracing multi attach benchmark test
      selftests/bpf: Add tracing multi attach rollback tests

 arch/arm64/net/bpf_jit_comp.c                                      |  58 +++---
 arch/loongarch/net/bpf_jit.c                                       |  44 ++---
 arch/powerpc/net/bpf_jit_comp.c                                    |  46 ++---
 arch/riscv/net/bpf_jit_comp64.c                                    |  52 ++---
 arch/s390/net/bpf_jit_comp.c                                       |  44 ++---
 arch/x86/net/bpf_jit_comp.c                                        |  54 ++---
 include/linux/bpf.h                                                | 102 +++++++---
 include/linux/bpf_types.h                                          |   1 +
 include/linux/bpf_verifier.h                                       |   3 +
 include/linux/btf_ids.h                                            |   1 +
 include/linux/ftrace.h                                             |   2 +
 include/linux/trace_events.h                                       |   6 +
 include/uapi/linux/bpf.h                                           |   9 +
 kernel/bpf/bpf_struct_ops.c                                        |  27 +--
 kernel/bpf/btf.c                                                   |   4 +
 kernel/bpf/syscall.c                                               |  88 ++++++---
 kernel/bpf/trampoline.c                                            | 536 ++++++++++++++++++++++++++++++++++++++++---------
 kernel/bpf/verifier.c                                              | 124 +++++++++---
 kernel/trace/bpf_trace.c                                           | 149 +++++++++++++-
 kernel/trace/ftrace.c                                              |   9 +-
 net/bpf/bpf_dummy_struct_ops.c                                     |  14 +-
 net/bpf/test_run.c                                                 |   3 +
 tools/include/uapi/linux/bpf.h                                     |  10 +
 tools/lib/bpf/bpf.c                                                |   9 +
 tools/lib/bpf/bpf.h                                                |   5 +
 tools/lib/bpf/libbpf.c                                             | 337 ++++++++++++++++++++++++++++++-
 tools/lib/bpf/libbpf.h                                             |  15 ++
 tools/lib/bpf/libbpf.map                                           |   1 +
 tools/lib/bpf/libbpf_internal.h                                    |   1 +
 tools/testing/selftests/bpf/Makefile                               |   9 +-
 tools/testing/selftests/bpf/prog_tests/tracing_multi.c             | 912 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/tracing_multi_attach.c           |  39 ++++
 tools/testing/selftests/bpf/progs/tracing_multi_attach_module.c    |  25 +++
 tools/testing/selftests/bpf/progs/tracing_multi_bench.c            |  12 ++
 tools/testing/selftests/bpf/progs/tracing_multi_check.c            | 212 ++++++++++++++++++++
 tools/testing/selftests/bpf/progs/tracing_multi_fail.c             |  18 ++
 tools/testing/selftests/bpf/progs/tracing_multi_intersect_attach.c |  41 ++++
 tools/testing/selftests/bpf/progs/tracing_multi_rollback.c         |  43 ++++
 tools/testing/selftests/bpf/progs/tracing_multi_session_attach.c   |  43 ++++
 tools/testing/selftests/bpf/trace_helpers.c                        |   6 +-
 tools/testing/selftests/bpf/trace_helpers.h                        |   1 +
 41 files changed, 2749 insertions(+), 366 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/tracing_multi.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_attach.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_attach_module.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_bench.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_check.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_fail.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_intersect_attach.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_rollback.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_session_attach.c