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Subject[PATCH] perf parse events: Fix invalid precise_ip handling
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When the user set a precise_ip greater than the highest precision available,
perf should return EINVAL to indicate the invalid precise_ip setting.

Currently, in get_event_modifier(), perf compares the user-specified precise_ip
with 3, instead of the highest precision available in the current processor.
It is incorrect if the maximum precision available is less than 3.

For example, with a highest precision perf_event_attr.precise_ip = 2, the
user-specified precise_ip greater than 2 should be handled as invalid argument.

Introduce perf_get_max_precise_ip() to get max precision available and compare
it with the user-specified precise_ip. Also show the available max precision in
an error message when the user-specified precise_ip is invalid.

Before:
$./perf record -e cycles:ppp sleep 1
Error:
PMU Hardware doesn't support sampling/overflow-interrupts.

After:
$./perf record -e cycles:ppp sleep 1
Error: Invalid argument for precise_ip setting.
The highest level of precise ip is 2
invalid or unsupported event: 'cycles:ppp'
Run 'perf list' for a list of valid events

Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]

-e, --event <event> event selector. use 'perf list' to list available events

Signed-off-by: Mengting Zhang <zhangmengting@huawei.com>
---
tools/perf/util/parse-events.c | 33 ++++++++++++++++++++++++++++++++-
1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 39b1596..25225f4 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1369,6 +1369,32 @@ struct event_modifier {
int pinned;
};

+static int perf_get_max_precise_ip(void)
+{
+ int max_precise_ip = 0;
+ struct perf_event_attr attr = {
+ .type = PERF_TYPE_HARDWARE,
+ .config = PERF_COUNT_HW_CPU_CYCLES,
+ };
+
+ event_attr_init(&attr);
+
+ attr.precise_ip = 3;
+ attr.sample_period = 1;
+
+ while (attr.precise_ip != 0) {
+ int fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
+ if (fd != -1){
+ close(fd);
+ break;
+ }
+ --attr.precise_ip;
+ }
+ max_precise_ip = attr.precise_ip;
+
+ return max_precise_ip;
+}
+
static int get_event_modifier(struct event_modifier *mod, char *str,
struct perf_evsel *evsel)
{
@@ -1382,6 +1408,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
int precise_max = 0;
int sample_read = 0;
int pinned = evsel ? evsel->attr.pinned : 0;
+ int max_precise_ip = 0;

int exclude = eu | ek | eh;
int exclude_GH = evsel ? evsel->exclude_GH : 0;
@@ -1438,8 +1465,12 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
*
* See also PERF_RECORD_MISC_EXACT_IP
*/
- if (precise > 3)
+ max_precise_ip = perf_get_max_precise_ip();
+ if (precise > max_precise_ip) {
+ pr_err("Error: Invalid argument for precise_ip setting. \n"
+ "The highest level of precise ip is %d\n", max_precise_ip);
return -EINVAL;
+ }

mod->eu = eu;
mod->ek = ek;
--
1.7.12.4
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