From 022bcb6ba2d384d772f68477d11b2684afd6e715 Mon Sep 17 00:00:00 2001 From: Michael Liang Date: Tue, 28 Jul 2026 14:42:15 -0600 Subject: [PATCH] perf libdw: Fix outer-frame name resolution and spurious "(inlined)" tag 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: 88c51002d06f9a68 ("perf addr2line: Add a libdw implementation") Signed-off-by: Michael Liang Reviewed-by: James Clark Signed-off-by: Namhyung Kim --- tools/perf/util/libdw.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/libdw.c b/tools/perf/util/libdw.c index d5d2958902c0..4ca7e7e4fbe9 100644 --- a/tools/perf/util/libdw.c +++ b/tools/perf/util/libdw.c @@ -82,13 +82,39 @@ struct libdw_a2l_cb_args { static int libdw_a2l_cb(Dwarf_Die *die, void *_args) { struct libdw_a2l_cb_args *args = _args; - struct symbol *inline_sym = new_inline_sym(args->dso, args->sym, die_name(die)); const char *call_fname = die_get_call_file(die); int call_lineno = die_get_call_lineno(die); char *call_srcline = srcline__unknown; + struct symbol *inline_sym; - if (!inline_sym) - goto abort_enomem; + if (dwarf_tag(die) == DW_TAG_subprogram && args->sym) { + /* + * cu_walk_functions_at() opens the walk with the + * containing DW_TAG_subprogram DIE (the non-inlined outer + * function). That's just the base symbol -- use it + * directly. Avoids a fragile name-vs-name compare in + * new_inline_sym() that misfires when GCC IPA passes + * (.isra/.constprop/.part/.cold) rename the ELF symbol + * while DWARF keeps the pre-clone linkage name, which + * left the outer frame spuriously tagged "(inlined)". + */ + inline_sym = args->sym; + } else { + /* + * Prefer DW_AT_linkage_name so C++ inline frames keep + * their namespace/class qualification. new_inline_sym() + * runs the name through dso__demangle_sym(), so the + * mangled linkage name is turned back into + * "Namespace::Class::method". Fall back to DW_AT_name + * (unqualified) when no linkage name is present, e.g. + * for C code or extern "C" functions. + */ + const char *funcname = die_get_linkage_name(die) ?: die_name(die); + + inline_sym = new_inline_sym(args->dso, args->sym, funcname); + if (!inline_sym) + goto abort_enomem; + } /* Assign caller information to the parent. */ if (call_fname)