linux-kernel - [PATCH 3.16 026/306] perf symbols: Fixup symbol sizes before picking best ones

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Date:   Wed, 15 Feb 2017 22:41:40 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Wang Nan" <wangnan0@...wei.com>,
        "Anton Blanchard" <anton@...ba.org>,
        "Namhyung Kim" <namhyung@...nel.org>,
        "David Ahern" <dsahern@...il.com>, "Jiri Olsa" <jolsa@...nel.org>,
        "Masami Hiramatsu" <mhiramat@...nel.org>,
        "Arnaldo Carvalho de Melo" <acme@...hat.com>,
        "Adrian Hunter" <adrian.hunter@...el.com>
Subject: [PATCH 3.16 026/306] perf symbols: Fixup symbol sizes before
 picking best ones

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Arnaldo Carvalho de Melo <acme@...hat.com>

commit 432746f8e0b6a82ba832b771afe31abd51af6752 upstream.

When we call symbol__fixup_duplicate() we use algorithms to pick the
"best" symbols for cases where there are various functions/aliases to an
address, and those check zero size symbols, which, before calling
symbol__fixup_end() are _all_ symbols in a just parsed kallsyms file.

So first fixup the end, then fixup the duplicates.

Found while trying to figure out why 'perf test vmlinux' failed, see the
output of 'perf test -v vmlinux' to see cases where the symbols picked
as best for vmlinux don't match the ones picked for kallsyms.

Cc: Anton Blanchard <anton@...ba.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Wang Nan <wangnan0@...wei.com>
Fixes: 694bf407b061 ("perf symbols: Add some heuristics for choosing the best duplicate symbol")
Link: http://lkml.kernel.org/n/tip-rxqvdgr0mqjdxee0kf8i2ufn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 tools/perf/util/symbol-elf.c | 2 +-
 tools/perf/util/symbol.c     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -958,8 +958,8 @@ new_symbol:
 	 * For misannotated, zeroed, ASM function sizes.
 	 */
 	if (nr > 0) {
-		symbols__fixup_duplicate(&dso->symbols[map->type]);
 		symbols__fixup_end(&dso->symbols[map->type]);
+		symbols__fixup_duplicate(&dso->symbols[map->type]);
 		if (kmap) {
 			/*
 			 * We need to fixup this here too because we create new
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1176,8 +1176,8 @@ int dso__load_kallsyms(struct dso *dso,
 	if (kallsyms__delta(map, filename, &delta))
 		return -1;
 
-	symbols__fixup_duplicate(&dso->symbols[map->type]);
 	symbols__fixup_end(&dso->symbols[map->type]);
+	symbols__fixup_duplicate(&dso->symbols[map->type]);
 
 	if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
 		dso->symtab_type = DSO_BINARY_TYPE__GUEST_KALLSYMS;