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From: Stephane Eranian on 17 May 2010 06:40
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.

Signed-off-by: Stephane Eranian <eranian(a)google.com>
--
tools/perf/builtin-record.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 0f467cf..78f64cc 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;
@@ -901,7 +901,7 @@ 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;
--
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