[PATCH v3 0/7] perf annotate: Add elfutils libasm disassembler and BPF JIT disassembly support

[Ian Rogers <irogers@google.com>]

This patch series introduces support for using the elfutils `libasm` library
as a disassembler backend in `perf annotate`. This provides a lightweight,
library-based alternative to LLVM and Capstone for in-process disassembly.

Additionally, this series implements disassembly support for in-memory BPF
JITted programs by writing the JITted instruction buffer to a temporary ELF
file on the fly and disassembling it using the ELF-based backends (`objdump`
and `libasm`).

Changes in v3:
- Address review comments on v2 series.
- Explicitly link against `-lasm -ldw -lelf` in the feature check.
- Document that older versions of elfutils that require explicitly linking
  `-lebl` statically are unsupported.
- Fix instruction-by-instruction disassembly loop logic in `libasm.c` by
  returning 1 from output callback and checking for `ret != 1`.
- Pass the correct ELF machine (`e_machine`) to `jit_write_elf` instead of
  hardcoding host architecture.
- Update `annotate.sh` tests to use `perf test -w` workload instead of `free`
  to avoid CI environment issues.
- Expand test coverage to test all disassemblers (including libasm) on BPF
  JIT symbols when run with root privileges.


Ian Rogers (7):
  tools build: Add feature check for elfutils libasm
  perf build: Add build support and capability for elfutils libasm
  perf annotate: Implement elfutils libasm disassembler backend
  perf annotate: Add --disassembler command-line option
  perf test: Enhance annotate test coverage and isolate config
  perf annotate: Support BPF JIT disassembly via genelf
  perf test: Add BPF JIT annotation test coverage for all disassemblers

 tools/build/Makefile.feature       |   2 +
 tools/build/feature/Makefile       |   9 ++
 tools/build/feature/test-libasm.c  |  20 ++++
 tools/perf/Makefile.config         |  22 ++++
 tools/perf/builtin-annotate.c      |  10 ++
 tools/perf/builtin-check.c         |   1 +
 tools/perf/tests/genelf.c          |   2 +-
 tools/perf/tests/shell/annotate.sh | 153 ++++++++++++++++++++++++
 tools/perf/util/Build              |   1 +
 tools/perf/util/annotate.c         |   8 +-
 tools/perf/util/annotate.h         |   3 +
 tools/perf/util/disasm.c           | 114 +++++++++++++++++-
 tools/perf/util/disasm.h           |   1 +
 tools/perf/util/genelf.c           |  16 +--
 tools/perf/util/genelf.h           |   2 +-
 tools/perf/util/jitdump.c          |   3 +-
 tools/perf/util/libasm.c           | 184 +++++++++++++++++++++++++++++
 tools/perf/util/libasm.h           |  27 +++++
 18 files changed, 559 insertions(+), 19 deletions(-)
 create mode 100644 tools/build/feature/test-libasm.c
 create mode 100644 tools/perf/util/libasm.c
 create mode 100644 tools/perf/util/libasm.h

-- 
2.54.0.1099.g489fc7bff1-goog