linux.git/tools/bpf/resolve_btfids, branch master

Merge tag 'perf-tools-for-v7.3-2026-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools

2026-08-22T15:47:50+00:00

Pull perf tools updates from Namhyung Kim:
 "perf c2c:

   - Add 'function view' in perf c2c report TUI (switched by pressing
     'TAB' in the cacheline view) to organize samples around functions
     rather than cachelines in 3-level hierarchy:

	Level 1: Read-side function (sorted by estimated Cycles %)
	Level 2:   Contending writer functions (sorted by Store count)
	Level 3:     Shared cacheline addresses

     Users can navigate the entries and fold/unfold using 'e' key. An
     example output would look like below:

	Shared Data Functions Table     (19 entries, sorted on Cycles %)
	   Cycles    Store
	        %    count  Function / Contending function / Cacheline
	----------------------------------------------------------------------
	+  35.67%      876  + [k] cpupri_set
	+  24.31%      424  + [k] pull_rt_task
	-  16.53%      555  - [k] dequeue_pushable_task
	               145    - [k] pull_rt_task
	               145        0xff2d0082809da080
	               139    - [k] enqueue_pushable_task
	                70        0xff2d00a2071f9640
	                69        0xff2d0082809da000

  python module support:

   - Extend "perf" python module so that it can be fully functional. The
     goal is to run scripts directly, not by 'perf script' command. This
     would give better performance as well as more control to build
     standalone programs with UI.

   - Add LiveSession helper (perf_live.py) to enable live event
     collection directly from Python using perf.evlist and
     perf.parse_events.

  perf stat:

   - Add --hide-zero-events option to suppress zero-count events
   - Reject conflicting --field-separator and --json-output options
   - Fix duplicate event output with --for-each-cgroup

  perf sched latency:

   - Add -H/--histogram and --hist-mode (log|linear) options to show
     scheduler wait latency histograms
   - Add --time option to filter analysis by time span in 'perf sched
     latency'

  ARM CoreSight:

   - Synthesize callchains for instruction samples from CoreSight trace
     using thread stack ('--itrace=g...')
   - Support call indentation ('perf script -F +callindent') to display
     call depth hierarchy on branch samples
   - Decode ETE (Embedded Trace Extension) exception packets

  Build system:

   - Add 'make install-build-deps' target to install required packages
   - Parallelize JSON and metric pre-computation in jevents.py for
     faster builds

  Vendor event/metric updates:

   - Add Intel Nova Lake events and update tables for existing models
   - Update AMD Zen 5 and Zen 6 core events
   - Update Arm64 Tegra410 metrics and PowerPC hcalls

  Internal changes and fixes:

   - Harden trace-event and synthetic event parsing against corrupted
     data
   - Fix unwinding of multi-threaded processes in libdw unwinder
   - Fix memory leaks in various commands and python bindings
   - Speed up 'perf test' shell tests"

* tag 'perf-tools-for-v7.3-2026-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (232 commits)
  perf vendor events arm64: Fix Tegra410 Olympus event 0x0197
  perf vendor events arm64: fix swapped MetricGroup for Tegra410 L1 prefetcher metrics
  perf evlist: Warn when 'sleep' workload is used without system-wide (-a) option
  perf c2c: document function view in perf-c2c man page
  perf c2c: add function view browser UI and cacheline detail
  perf c2c: build and finalize the function view hierarchy
  perf c2c: add function view hierarchy entry creation
  perf c2c: add function view stats merge and memory management
  perf c2c: add HPP list parsing for function view columns
  perf c2c: add column rendering for function view
  perf c2c: add function view model skeleton
  perf c2c: extract shared data structures into util/c2c.h
  perf test sample-parsing: Validate PERF_FORMAT_GROUP values without LOST
  perf dso: Replace assert with runtime check in dso__read_symbol()
  perf dso: Guard against cache underflow on short reads in dso_cache__memcpy()
  perf dso: Use stored fd error instead of stale errno in file_read() and file_size()
  perf dso: Guard close() against invalid fd in dso__decompress_kmodule_path()
  perf dso: Guard against errno==0 when dso__get_filename() returns NULL
  perf build: install-build-deps: add RHEL family devel package mapping
  perf build: Remove leftover feature tests for removed cxx and clang support
  ...

resolve_btfids: Emit arena attributes from kfunc parameter suffixes

2026-08-13T01:28:49+00:00

Kfunc declarations can identify arena arguments through parameter name
suffixes without repeating KF_ARENA_ARG flags in their BTF ID sets.
resolve_btfids currently misses those arguments when synthesizing the
address_space(1) attributes used by generated vmlinux.h files.

Teach the arena prototype rewrite to recognize __arena and
__arena__nullable directly on each parameter. Keep KF_ARENA_ARG1 and
KF_ARENA_ARG2 handling for explicitly flagged kfuncs, while allowing
suffixes on any argument without synthesizing kfunc flags.

Signed-off-by: Kumar Kartikeya Dwivedi 
Link: https://patch.msgid.link/20260812193842.2879226-2-memxor@gmail.com
Signed-off-by: Eduard Zingerman

docs, resolve_btfids: Document kfunc BTF annotation emission

2026-08-07T05:01:28+00:00

resolve_btfids now emits the bpf_kfunc and bpf_fastcall BTF decl tags and
the arena address_space(1) type attribute for kfuncs, which were
previously produced by pahole.

Reflect this in the in-tree comments and documentation.

Signed-off-by: Ihor Solodrai 
Reviewed-by: Emil Tsalapatis 
Link: https://patch.msgid.link/20260807032029.78092-7-ihor.solodrai@linux.dev
Signed-off-by: Eduard Zingerman

resolve_btfids: Emit bpf_kfunc and bpf_fastcall decl tags

2026-08-07T05:01:28+00:00

Emit the bpf_kfunc decl tag for every discovered kfunc, and bpf_fastcall
for kfuncs flagged KF_FASTCALL. These were previously produced by pahole
under --btf_features=decl_tag_kfuncs.

resolve_btfids now discovers kfuncs from the BTF ID sets [1] and
becomes the source of truth for their annotations.

Drop decl_tag_kfuncs pahole feature flag from scripts/Makefile.btf

[1] https://lore.kernel.org/all/20260722233518.778854-1-ihor.solodrai@linux.dev/

Signed-off-by: Ihor Solodrai 
Acked-by: Eduard Zingerman 
Link: https://patch.msgid.link/20260807032029.78092-5-ihor.solodrai@linux.dev
Signed-off-by: Eduard Zingerman

resolve_btfids: Process KF_ARENA_* flags in resolve_btfids

2026-08-07T05:01:28+00:00

For kfuncs flagged with KF_ARENA_RET, KF_ARENA_ARG1 or KF_ARENA_ARG2,
the address_space(1) attribute (a type tag with kflag=1) must be
emitted for the corresponding type in BTF. This was previously done by
pahole via the "attributes" BTF feature [1].

Implement the emission of the arena attributes in resolve_btfids: for
flagged kfuncs create a new function prototype with updated BTF types.
The original proto may be shared with sibling FUNCs, so it is not
modified in place.

Emission is unconditional: kbuild controls the pahole flags, so the
input BTF is expected to not have these attributes. Invalid
declarations are reported as errors.

Drop the "attributes" pahole feature from scripts/Makefile.btf
resolve_btfids now emits them for all supported pahole versions.

[1] https://lore.kernel.org/dwarves/20250228194654.1022535-1-ihor.solodrai@linux.dev/

Signed-off-by: Ihor Solodrai 
Link: https://patch.msgid.link/20260807032029.78092-3-ihor.solodrai@linux.dev
Signed-off-by: Eduard Zingerman

resolve_btfids: Deduplicate BTF after btf2btf transformations

2026-08-07T05:01:28+00:00

btf2btf() adds new types to the BTF: the KF_IMPLICIT_ARGS transform
synthesizes an _impl FUNC together with its FUNC_PROTO and copies of the
kfunc's decl tags. Nothing deduplicates them afterwards. pahole runs
btf__dedup() on its own output, but that happens before resolve_btfids
sees the BTF, so any type the tool itself creates is emitted as-is, even
when a structurally identical type is already present.

Call btf__dedup() at the start of finalize_btf(), so that base
distillation and the by-name sort both operate on the canonical set of
types.

On an x86_64 build with the BPF selftests config this removes 17
duplicate FUNC_PROTOs from vmlinux BTF.

The dedup call increases runtime of resolve_btfids on vmlinux by 30-40%.
The performance hit is an acceptable cost to keep kernel BTF deduped [1].

[1] https://lore.kernel.org/bpf/986e6f4e-4b51-4440-a37c-9624906d7370@linux.dev/

Signed-off-by: Ihor Solodrai 
Link: https://patch.msgid.link/20260807032029.78092-2-ihor.solodrai@linux.dev
Signed-off-by: Eduard Zingerman

resolve_btfids: Enforce consistent kfunc flags across BTF ID sets

2026-07-30T19:48:12+00:00

A kfunc may be listed in several BTF ID sets, which is expected
because different kfuncs are available to BPF programs depending on
their type.

However kfunc flags across different BTF ID sets must be consistent [1].
The flags should be considered a part of the kfunc declaration,
because they influence its BTF representation and verifier handling.

Enforce the kfunc flag consistency in resolve_btifds by hard failing
on error and blocking kernel (or module) build.

[1] https://lore.kernel.org/bpf/9b2196dd-443b-4632-ae11-030cdbdc59b4@linux.dev/

Signed-off-by: Ihor Solodrai 
Signed-off-by: Andrii Nakryiko 
Reviewed-by: Eduard Zingerman 
Link: https://lore.kernel.org/bpf/20260722233518.778854-9-ihor.solodrai@linux.dev

resolve_btfids: Discover kfuncs from BTF ID sets

2026-07-30T19:48:11+00:00

collect_kfuncs() currently uses bpf_kfunc decl tags to identify the
list of kfuncs. The decl tags are generated by pahole, which makes
current implementation implicitly rely on those tags being generated.

The authoritative source, used by the the BPF verifier for kfunc
registration, of functions being BPF kfuncs are
BTF_KFUNCS_START()/END() declarations. These are BTF_ID_SET8 under the
hood. Currently resolve_btfids reads kfunc flags from these sets, and
populates them with BTF IDs.

Implement kfunc discovery from BTF_ID_SET8 symbols in resolve_btfids,
removing the dependency on pahole's emmission of decl tags.

Walk BTF_ID_KIND_SET8 sets, and use the address-to-symbol index to
look up set entry's BTF_ID symbol name (before .BTF_ids is patched),
recording the paired flags directly. This makes find_kfunc_flags()
helper unnecessary, so it's removed.

Signed-off-by: Ihor Solodrai 
Signed-off-by: Andrii Nakryiko 
Reviewed-by: Eduard Zingerman 
Link: https://lore.kernel.org/bpf/20260722233518.778854-8-ihor.solodrai@linux.dev

resolve_btfids: Fix the _impl lookup for module BTF

2026-07-30T19:48:08+00:00

process_kfunc_with_implicit_args() skips generating _impl
function when one already exists for backwards compatibility.

It uses btf__find_by_name_kind(), which searches the base BTF before
the split BTF. When resolve_btfids processes a module, a same-named
_impl in vmlinux would be found and the module's own counterpart would
not be created.

Fix by using btf__find_by_name_kind_own() for the lookup.

Signed-off-by: Ihor Solodrai 
Signed-off-by: Andrii Nakryiko 
Reviewed-by: Eduard Zingerman 
Link: https://lore.kernel.org/bpf/20260722233518.778854-6-ihor.solodrai@linux.dev

resolve_btfids: Keep collected kfuncs in a rbtree

2026-07-30T19:48:07+00:00

Store collected kfuncs in a rbtree keyed by BTF ID instead of a
dynamically grown array. This allows for efficient deduplication for
kfuncs declared in multiple sets, which is needed for subsequent
patches [1].

[1] https://lore.kernel.org/bpf/CAEf4BzaLzX3mXvQzxv+gbmZOh84XvYofLjMSWFYghNjS-ohEZg@mail.gmail.com/

Signed-off-by: Ihor Solodrai 
Signed-off-by: Andrii Nakryiko 
Reviewed-by: Eduard Zingerman 
Link: https://lore.kernel.org/bpf/20260722233518.778854-4-ihor.solodrai@linux.dev