[PATCH v2 0/7] perf annotate: Add elfutils libasm disassembler support

[Ian Rogers <irogers@google.com>]

This series adds a new `libasm` disassembly backend to `perf annotate`,
leveraging the `elfutils` libasm library. This allows perf to use the
widely available elfutils for disassembly alongside capstone, libLLVM, and objdump.

v2 changes:
- Patch 1: Added a note to the commit message acknowledging that older elfutils static builds lacking `-lebl` dependencies in pkg-config are explicitly unsupported, while intentionally retaining the feature check and API dependencies.
- Patch 2: Fixed `NO_LIBELF=1` build breakages by implicitly disabling `libasm` and removing the unconditional `#warning` in favor of silent fallbacks or standard warnings.
- Patch 3: Fixed `libasm` block boundary tracking and corrected callback error/return values, preventing memory leaks and infinite loops in the disassembly extraction loop.
- Patch 5: Fixed script robustness in `tests/shell/annotate.sh` by ensuring cleanup functions run reliably, `set -e` doesn't abort prematurely on grep failures, and configs are properly restored.
- Patch 6: Refactored `jit_write_elf` to accept the `e_machine` parameter directly instead of post-patching the generated ELF file with `libelf`. The target architecture is now extracted dynamically and passed into `jit_write_elf`, simplifying the interaction with BPF and making it fully compatible with all disassemblers.
- Patch 7: Fixed a TOCTOU race condition when creating the symlink in `tests/shell/annotate.sh` by placing `perf.data` inside an isolated temporary directory.
- General: The cover letter now lists capstone, libLLVM, and objdump as the existing disassemblers instead of just objdump.

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  |  19 +++
 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 | 133 +++++++++++++++++++++
 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           |   4 +-
 tools/perf/util/genelf.h           |   2 +-
 tools/perf/util/jitdump.c          |   2 +-
 tools/perf/util/libasm.c           | 184 +++++++++++++++++++++++++++++
 tools/perf/util/libasm.h           |  27 +++++
 18 files changed, 531 insertions(+), 13 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

--
2.54.0.1064.gd145956f57-goog