Re: [PATCHv4 bpf-next 00/25] bpf: tracing_multi link

[Leon Hwang <leon.hwang@linux.dev>]

Hi Jiri,

Nice version for tracing_multi link.

I hope I have time to add tracing_multi link support to bpfsnoop, and
test this new tracing feature.

I left comments on patches #13, #24, and #25.

Hope this series lands in bpf-next soon.

Thanks,
Leon

On 24/3/26 16:18, Jiri Olsa wrote:
> 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-jolsa@kernel.org/
> v1: https://lore.kernel.org/bpf/20260220100649.628307-1-jolsa@kernel.org/
> v2: https://lore.kernel.org/bpf/20260304222141.497203-1-jolsa@kernel.org/
> v3: https://lore.kernel.org/bpf/20260316075138.465430-1-jolsa@kernel.org/
> 
> 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
>