From a9ffd0484eb4426e6befd07e7be6c01108716302 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Fri, 27 Nov 2020 14:48:55 +0900 Subject: [PATCH] perf probe: Change function definition check due to broken DWARF Since some gcc generates a broken DWARF which lacks DW_AT_declaration attribute from the subprogram DIE of function prototype. (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97060) So, in addition to the DW_AT_declaration check, we also check the subprogram DIE has DW_AT_inline or actual entry pc. Committer testing: # cat /etc/fedora-release Fedora release 33 (Thirty Three) # Before: # perf test vfs_getname 78: Use vfs_getname probe to get syscall args filenames : FAILED! 79: Check open filename arg using perf trace + vfs_getname : FAILED! 81: Add vfs_getname probe to get syscall args filenames : FAILED! # After: # perf test vfs_getname 78: Use vfs_getname probe to get syscall args filenames : Ok 79: Check open filename arg using perf trace + vfs_getname : Ok 81: Add vfs_getname probe to get syscall args filenames : Ok # Reported-by: Thomas Richter Signed-off-by: Masami Hiramatsu Tested-by: Arnaldo Carvalho de Melo Cc: Sumanth Korikkar Link: http://lore.kernel.org/lkml/160645613571.2824037.7441351537890235895.stgit@devnote2 Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/dwarf-aux.c | 20 ++++++++++++++++++-- tools/perf/util/probe-finder.c | 3 +-- 2 files changed, 19 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index 03c1a39c312a..7b2d471a6419 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -356,9 +356,25 @@ bool die_is_signed_type(Dwarf_Die *tp_die) bool die_is_func_def(Dwarf_Die *dw_die) { Dwarf_Attribute attr; + Dwarf_Addr addr = 0; + + if (dwarf_tag(dw_die) != DW_TAG_subprogram) + return false; + + if (dwarf_attr(dw_die, DW_AT_declaration, &attr)) + return false; - return (dwarf_tag(dw_die) == DW_TAG_subprogram && - dwarf_attr(dw_die, DW_AT_declaration, &attr) == NULL); + /* + * DW_AT_declaration can be lost from function declaration + * by gcc's bug #97060. + * So we need to check this subprogram DIE has DW_AT_inline + * or an entry address. + */ + if (!dwarf_attr(dw_die, DW_AT_inline, &attr) && + die_entrypc(dw_die, &addr) < 0) + return false; + + return true; } /** diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 2c4061035f77..76dd349aa48d 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -1885,8 +1885,7 @@ static int line_range_search_cb(Dwarf_Die *sp_die, void *data) if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die))) return DWARF_CB_OK; - if (die_is_func_def(sp_die) && - die_match_name(sp_die, lr->function)) { + if (die_match_name(sp_die, lr->function) && die_is_func_def(sp_die)) { lf->fname = dwarf_decl_file(sp_die); dwarf_decl_line(sp_die, &lr->offset); pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset); -- 2.25.1