linux-kernel - [PATCH 24/47] perf symbols: avoid SyS kernel syscall aliases

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Message-Id: <1375909874-22073-25-git-send-email-acme@infradead.org>
Date:	Wed,  7 Aug 2013 18:10:51 -0300
From:	Arnaldo Carvalho de Melo <acme@...radead.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>, Mike Galbraith <efault@....de>,
	Namhyung Kim <namhyung@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 24/47] perf symbols: avoid SyS kernel syscall aliases

From: Adrian Hunter <adrian.hunter@...el.com>

When removing duplicate symbols, prefer to remove syscall aliases
starting with SyS or compat_SyS.

A side-effect of that is that it results in slightly improved results
for the "vmlinux symtab matches kallsyms" test.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Mike Galbraith <efault@....de>
Cc: Namhyung Kim <namhyung@...il.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Link: http://lkml.kernel.org/r/1375875537-4509-6-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/symbol.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 02718e7..ea62ecd 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -87,6 +87,7 @@ static int choose_best_symbol(struct symbol *syma, struct symbol *symb)
 {
 	s64 a;
 	s64 b;
+	size_t na, nb;
 
 	/* Prefer a symbol with non zero length */
 	a = syma->end - syma->start;
@@ -120,11 +121,21 @@ static int choose_best_symbol(struct symbol *syma, struct symbol *symb)
 	else if (a > b)
 		return SYMBOL_B;
 
-	/* If all else fails, choose the symbol with the longest name */
-	if (strlen(syma->name) >= strlen(symb->name))
+	/* Choose the symbol with the longest name */
+	na = strlen(syma->name);
+	nb = strlen(symb->name);
+	if (na > nb)
 		return SYMBOL_A;
-	else
+	else if (na < nb)
+		return SYMBOL_B;
+
+	/* Avoid "SyS" kernel syscall aliases */
+	if (na >= 3 && !strncmp(syma->name, "SyS", 3))
 		return SYMBOL_B;
+	if (na >= 10 && !strncmp(syma->name, "compat_SyS", 10))
+		return SYMBOL_B;
+
+	return SYMBOL_A;
 }
 
 void symbols__fixup_duplicate(struct rb_root *symbols)
-- 
1.8.1.4

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