[PATCH v1 0/2] perf libdw: Improve split-debug handling and error fallback

[Ian Rogers <irogers@google.com>]

This patch series improves libdw's handling of split debuginfo files and its
fallback logic when DWARF data is unstructured or completely absent.

When perf's libdw backend failed to read unwinding or inlining states
due to un-mapped lines (returning 0), the addr2line_style routine fell
back to executing the system's `addr2line` potentially launching many
sub-processes.

Patch 1 Ensures split debug information is properly handled.
Patch 2 checks `dwfl_errmsg(-1)` for "no DWARF" presence to avoid
fallbacks.

Ian Rogers (2):
  perf libdw: Pass dso_name explicitly to properly anchor split-debug
    builds
  perf libdw: Optimize fallback logic for missing DWARF

 .../arch/powerpc/util/skip-callchain-idx.c    |  2 +-
 tools/perf/util/dso.h                         |  5 +++--
 tools/perf/util/libdw.c                       | 21 ++++++++++++-------
 tools/perf/util/libdw.h                       |  5 +++--
 tools/perf/util/srcline.c                     |  4 +++-
 tools/perf/util/unwind-libdw.c                | 15 ++++++++++---
 6 files changed, 36 insertions(+), 16 deletions(-)

-- 
2.55.0.766.g2966f0265a-goog