From: Namhyung Kim <namhyung@kernel.org>
Date: Thu, 2 Jan 2025 20:32:51 +0000 (-0800)
Subject: perf symbol: Prefer non-label symbols with same address
X-Git-Tag: v6.14-rc1~29^2~42
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=8c2eafbbfd782d6ad270ca2de21b529ac57de0f4;p=linux-block.git

perf symbol: Prefer non-label symbols with same address

When there are more than one symbols at the same address, it needs to
choose which one is better.  In choose_best_symbol() it didn't check the
type of symbols.  It's possible to have labels in other symbols and in
that case, it would be better to pick the actual symbol over the labels.
To minimize the possible impact on other symbols, I only check NOTYPE
symbols specifically.

  $ readelf -sW vmlinux | grep -e __do_softirq -e __softirqentry_text_start
  105089: ffffffff82000000   814 FUNC    GLOBAL DEFAULT    1 __do_softirq
  111954: ffffffff82000000     0 NOTYPE  GLOBAL DEFAULT    1 __softirqentry_text_start

The commit 77b004f4c5c3c90b tried to do the same by not giving the size
to the label symbols but it seems there's some label-only symbols in asm
code.  Let's restore the original code and choose the right symbol using
type of the symbols.

Fixes: 77b004f4c5c3c90b ("perf symbol: Do not fixup end address of labels")
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Ian Rogers <irogers@google.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Link: http://lore.kernel.org/lkml/Z3b-DqBMnNb4ucEm@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 0037f1163919..49b08adc6ee3 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -154,6 +154,13 @@ static int choose_best_symbol(struct symbol *syma, struct symbol *symb)
 	else if ((a == 0) && (b > 0))
 		return SYMBOL_B;
 
+	if (syma->type != symb->type) {
+		if (syma->type == STT_NOTYPE)
+			return SYMBOL_B;
+		if (symb->type == STT_NOTYPE)
+			return SYMBOL_A;
+	}
+
 	/* Prefer a non weak symbol over a weak one */
 	a = syma->binding == STB_WEAK;
 	b = symb->binding == STB_WEAK;
@@ -257,7 +264,7 @@ void symbols__fixup_end(struct rb_root_cached *symbols, bool is_kallsyms)
 		 * like in:
 		 *   ffffffffc1937000 T hdmi_driver_init  [snd_hda_codec_hdmi]
 		 */
-		if (prev->end == prev->start && prev->type != STT_NOTYPE) {
+		if (prev->end == prev->start) {
 			const char *prev_mod;
 			const char *curr_mod;