linux-kernel - [PATCH 2/3] perf record: Fix bug mismatch with -c option definition

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Date:	Mon, 17 May 2010 12:47:57 -0300
From:	Arnaldo Carvalho de Melo <acme@...radead.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org,
	Stephane Eranian <eranian@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 2/3] perf record: Fix bug mismatch with -c option definition

From: Stephane Eranian <eranian@...gle.com>

The -c option defines the user requested sampling period. It was implemented
using an unsigned int variable but the type of the option was OPT_LONG. Thus,
the option parser was overwriting memory belonging to other variables, namely
the mmap_pages leading to a zero page sampling buffer. The bug was exposed only
when compiling at -O0, probably because the compiler was padding variables at
higher optimization levels.

This patch fixes this problem by declaring user_interval as u64. This also
avoids wrap-around issues for large period on 32-bit systems.

Commiter note:

Made it use OPT_U64(user_interval) after implementing OPT_U64 in the
previous patch.

Cc: David S. Miller <davem@...emloft.net>
Cc: Frédéric Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
LKML-Reference: <4bf11ae9.e88cd80a.06b0.ffffa8e3@...google.com>
Signed-off-by: Stephane Eranian <eranian@...gle.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-record.c |   11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 0f467cf..b93573c 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -33,8 +33,8 @@ enum write_mode_t {
 
 static int			*fd[MAX_NR_CPUS][MAX_COUNTERS];
 
-static unsigned int		user_interval 			= UINT_MAX;
-static long			default_interval		=      0;
+static u64			user_interval			= ULLONG_MAX;
+static u64			default_interval		=      0;
 
 static int			nr_cpus				=      0;
 static unsigned int		page_size;
@@ -268,7 +268,7 @@ static void create_counter(int counter, int cpu)
 	 * it a weak assumption overridable by the user.
 	 */
 	if (!attr->sample_period || (user_freq != UINT_MAX &&
-				     user_interval != UINT_MAX)) {
+				     user_interval != ULLONG_MAX)) {
 		if (freq) {
 			attr->sample_type	|= PERF_SAMPLE_PERIOD;
 			attr->freq		= 1;
@@ -817,8 +817,7 @@ static const struct option options[] = {
 			    "CPU to profile on"),
 	OPT_BOOLEAN('f', "force", &force,
 			"overwrite existing data file (deprecated)"),
-	OPT_LONG('c', "count", &user_interval,
-		    "event period to sample"),
+	OPT_U64('c', "count", &user_interval, "event period to sample"),
 	OPT_STRING('o', "output", &output_name, "file",
 		    "output file name"),
 	OPT_BOOLEAN('i', "no-inherit", &no_inherit,
@@ -901,7 +900,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
 	if (!event_array)
 		return -ENOMEM;
 
-	if (user_interval != UINT_MAX)
+	if (user_interval != ULLONG_MAX)
 		default_interval = user_interval;
 	if (user_freq != UINT_MAX)
 		freq = user_freq;
-- 
1.6.2.5

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