• Georg Müller's avatar
    perf probe: Read DWARF files from the correct CU · c66e1c68
    Georg Müller authored
    After switching from dwarf_decl_file() to die_get_decl_file(), it is not
    possible to add probes for certain functions:
    
      $ perf probe -x /usr/lib/systemd/systemd-logind match_unit_removed
      A function DIE doesn't have decl_line. Maybe broken DWARF?
      A function DIE doesn't have decl_line. Maybe broken DWARF?
      Probe point 'match_unit_removed' not found.
         Error: Failed to add events.
    
    The problem is that die_get_decl_file() uses the wrong CU to search for
    the file. elfutils commit e1db5cdc9f has some good explanation for this:
    
        dwarf_decl_file uses dwarf_attr_integrate to get the DW_AT_decl_file
        attribute. This means the attribute might come from a different DIE
        in a different CU. If so, we need to use the CU associated with the
        attribute, not the original DIE, to resolve the file name.
    
    This patch uses the same source of information as elfutils: use attribute
    DW_AT_decl_file and use this CU to search for the file.
    
    Fixes: dc9a5d2c ("perf probe: Fix to get declared file name from clang DWARF5")
    Signed-off-by: default avatarGeorg Müller <georgmueller@gmx.net>
    Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Ian Rogers <irogers@google.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: regressions@lists.linux.dev
    Cc: stable@vger.kernel.org
    Link: https://lore.kernel.org/r/20230628084551.1860532-6-georgmueller@gmx.netSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    c66e1c68
dwarf-aux.c 36.1 KB