perf, x86: Improve the PEBS ABI
Rename perf_event_attr::precise to perf_event_attr::precise_ip and
widen it to 2 bits. This new field describes the required precision of
the PERF_SAMPLE_IP field:
0 - SAMPLE_IP can have arbitrary skid
1 - SAMPLE_IP must have constant skid
2 - SAMPLE_IP requested to have 0 skid
3 - SAMPLE_IP must have 0 skid
And modify the Intel PEBS code accordingly. The PEBS implementation
now supports up to precise_ip == 2, where we perform the IP fixup.
Also s/PERF_RECORD_MISC_EXACT/&_IP/ to clarify its meaning, this bit
should be set for each PERF_SAMPLE_IP field known to match the actual
instruction triggering the event.
This new scheme allows for a PEBS mode that uses the buffer for more
than a single event.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 6be4a0f..23cd005 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -203,9 +203,19 @@
enable_on_exec : 1, /* next exec enables */
task : 1, /* trace fork/exit */
watermark : 1, /* wakeup_watermark */
- precise : 1, /* OoO invariant counter */
+ /*
+ * precise_ip:
+ *
+ * 0 - SAMPLE_IP can have arbitrary skid
+ * 1 - SAMPLE_IP must have constant skid
+ * 2 - SAMPLE_IP requested to have 0 skid
+ * 3 - SAMPLE_IP must have 0 skid
+ *
+ * See also PERF_RECORD_MISC_EXACT_IP
+ */
+ precise_ip : 2, /* skid constraint */
- __reserved_1 : 48;
+ __reserved_1 : 47;
union {
__u32 wakeup_events; /* wakeup every n events */
@@ -296,7 +306,12 @@
#define PERF_RECORD_MISC_GUEST_KERNEL (4 << 0)
#define PERF_RECORD_MISC_GUEST_USER (5 << 0)
-#define PERF_RECORD_MISC_EXACT (1 << 14)
+/*
+ * Indicates that the content of PERF_SAMPLE_IP points to
+ * the actual instruction that triggered the event. See also
+ * perf_event_attr::precise_ip.
+ */
+#define PERF_RECORD_MISC_EXACT_IP (1 << 14)
/*
* Reserve the last bit to indicate some extended misc field
*/