Adding sysfs 'precise' attribute for cpu device
(/sys/devices/cpu/precise) to show the maximum
value for perf event precise_ip attribute.
This will be used to put proper precise_ip when
configuring an event and and to automatically test
precise stuff to some extend.
Signed-off-by: Jiri Olsa <jo...@redhat.com>
Cc: Corey Ashford <cjash...@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Ingo Molnar <mi...@elte.hu>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Andi Kleen <a...@linux.intel.com>
Cc: David Ahern <dsah...@gmail.com>
Cc: Stephane Eranian <eran...@google.com>
---
arch/x86/kernel/cpu/perf_event.c | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 5ed7a4c..d38c9ea 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -377,19 +377,26 @@ static inline int precise_br_compat(struct perf_event
*event)
return m == b;
}
-int x86_pmu_hw_config(struct perf_event *event)
+static int x86_get_precise(void)
{
- if (event->attr.precise_ip) {
- int precise = 0;
+ int precise = 0;
- /* Support for constant skid */
- if (x86_pmu.pebs_active && !x86_pmu.pebs_broken) {
+ /* Support for constant skid */
+ if (x86_pmu.pebs_active && !x86_pmu.pebs_broken) {
+ precise++;
+
+ /* Support for IP fixup */
+ if (x86_pmu.lbr_nr)
precise++;
+ }
- /* Support for IP fixup */
- if (x86_pmu.lbr_nr)
- precise++;
- }
+ return precise;
+}
+
+int x86_pmu_hw_config(struct perf_event *event)
+{
+ if (event->attr.precise_ip) {
+ int precise = x86_get_precise();
if (event->attr.precise_ip > precise)
return -EOPNOTSUPP;
@@ -1734,6 +1741,13 @@ static int x86_pmu_event_init(struct perf_event *event)
return err;
}
+static ssize_t get_attr_precise(struct device *cdev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return snprintf(buf, 10, "%d\n", x86_get_precise());
+}
+
static int x86_pmu_event_idx(struct perf_event *event)
{
int idx = event->hw.idx;
@@ -1786,9 +1800,11 @@ static ssize_t set_attr_rdpmc(struct device *cdev,
}
static DEVICE_ATTR(rdpmc, S_IRUSR | S_IWUSR, get_attr_rdpmc, set_attr_rdpmc);
+static DEVICE_ATTR(precise, S_IRUGO, get_attr_precise, NULL);
static struct attribute *x86_pmu_attrs[] = {
&dev_attr_rdpmc.attr,
+ &dev_attr_precise.attr,
NULL,
};
--
1.7.11.7
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