Merge branch 'bpf-tracing_multi-link'

Jiri Olsa says:

====================
bpf: tracing_multi link

Add 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: https://lore.kernel.org/bpf/20260324081846.2334094-1-jolsa@kernel.org/
v5: https://lore.kernel.org/bpf/20260417192502.194548-1-jolsa@kernel.org/
v6: https://lore.kernel.org/bpf/20260527113951.46265-1-jolsa@kernel.org/
v7: https://lore.kernel.org/bpf/20260603110554.29590-1-jolsa@kernel.org/

v8 changes:
- add back the btf_is_union check to btf_get_type_size [sashiko]

v7 changes:
- added ftrace_hash_count stub for !CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS cade [sashiko]
- selftests fixes [sashiko]
- use hash_ptr in select_trampoline_lock [sashiko]
- changed the check duplicate logic in check_dup_ids [sashiko]
- use sort_r_nonatomic in check_dup_ids [sashiko]
- added BPF_TRACE_FSESSION_MULTI to can_be_sleepable,
  plus added testcase for sleepable fsession
- make bpf_tracing_multi_opts pointer fields as const
- add ___migrate_enable to trace_blacklist

v6 changes:
- move ftrace_hash_count declaration under CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS [sashiko]
- fix ftrace_hash_remove check/deref [sashiko]
- disable context access for multi programs by using stub function with no arguments
  for verification [sashiko]
- add __used for bpf_multi_func, and removed arguments, we do not allow direct access [sashiko]
- rebased on latest loongarch changes, fix ppc build
- guard update_ftrace_direct_del with ftrace_hash_count on rollback [sashiko]
- fix noreturn attachment condition in bpf_check_attach_btf_id_multi [sashiko]
- fail early on multiple same IDs provided by user [sashiko]
- fix selftests error paths [sashiko]
- add MAX_RESOLVE_DEPTH check to btf_get_type_size [sashiko]
- use btf__pointer_size [sashiko]
- fixed compilation on powerpc [sashiko]
- added verifier fails selftest
- after discussing with Song, it was determined that cleaning up FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER
  is not strictly necessary — keeping the trampoline in the ipmodify_enabled state is acceptable.
  The race condition this introduces remains unlikely, so the concern raised in [1] will not be
  addressed at this time.
  [1] https://lore.kernel.org/bpf/aec7bAbGlnEo3R1g@krava/

v5 changes:
- add dedicated hashes used for detach, so there's no need to allocate
  them on detach [sashiko]
- safely release old trampoline images [sashiko]
- add cond_resched() to couple of loops [sashiko]
- validate attr->link_create.target_fd [sashiko]
- allow only bpf_get_func_ret() for return value retrieval [sashiko]
- do not allow attachment of fexit/fsession_multi for noreturn functions [sashiko]
- fixed double free/close in libbpf btf cleanup, in separate patch [sashiko]
- make btf_type_is_traceable_func closer to btf_distill_func_proto [sashiko]
- add prog->attach_btf_obj_fd check to collect_func_ids_by_glob,
  to check we don't load module programs for kernel [sashiko]
- make sure program is loaded in bpf_program__attach_tracing_multi [sashiko]
- several selftests fixes [sashiko]
- add attach_type to fdinfo output [Leon Hwang]
- selftests cleanup fixes [Leon Hwang]

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
====================

Link: https://patch.msgid.link/20260606123955.345967-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>