perf libdw: Fix outer-frame name resolution and spurious "(inlined)" tag

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cu_walk_functions_at() calls libdw_a2l_cb() with the containing
DW_TAG_subprogram DIE first, then each DW_TAG_inlined_subroutine
nested inside.  The callback treated both the same way, causing two
bugs:

  1) die_name() returns the unqualified DW_AT_name, so every C++
     frame lost its namespace/class prefix (ns::Class::method
     collapsed to method).

  2) new_inline_sym() re-uses base_sym only when funcname matches
     base_sym->name exactly; otherwise it fabricates a fake symbol
     tagged "(inlined)".  Any mismatch between the DWARF name and
     the ELF symbol name mis-tags an outer, non-inline frame as
     inlined.  This hits C++ (die_name()'s unqualified output never
     matches the demangled ELF symbol) and it also hits C functions
     that GCC IPA-cloned (foo vs foo.isra.0 / .constprop / .part /
     .cold), since DW_AT_linkage_name doesn't reflect those renames.

Fix both:

  * Prefer die_get_linkage_name() (mangled, fully qualified),
    falling back to die_name() when absent (C, extern "C").
    new_inline_sym() already demangles via dso__demangle_sym().

  * For DW_TAG_subprogram DIEs, use base_sym directly -- the DIE
    tag already tells us it is the outer function, sidestepping
    the name comparison entirely for both C++ qualification and
    GCC IPA-clone renames.

Fixes: 88c51002d0 ("perf addr2line: Add a libdw implementation")
Signed-off-by: Michael Liang <mliang@purestorage.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

...

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Michael Liang 2026-07-28 14:42:15 -06:00 • committed by Namhyung Kim

parent f2effca1ef

commit 022bcb6ba2

1 changed files with 30 additions and 4 deletions

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tools/perf/util/libdw.c

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