perf/x86-ibs: Fix update of period

The last sw period was not correctly updated on overflow and thus led
to wrong distribution of events. We always need to properly initialize
data.period in struct perf_sample_data.

Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-2-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event_amd_ibs.c

@@ -386,7 +386,21 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
 	if (!(*buf++ & perf_ibs->valid_mask))
 		return 0;
 
+	/*
+	 * Emulate IbsOpCurCnt in MSRC001_1033 (IbsOpCtl), not
+	 * supported in all cpus. As this triggered an interrupt, we
+	 * set the current count to the max count.
+	 */
+	config = ibs_data.regs[0];
+	if (perf_ibs == &perf_ibs_op && !(ibs_caps & IBS_CAPS_RDWROPCNT)) {
+		config &= ~IBS_OP_CUR_CNT;
+		config |= (config & IBS_OP_MAX_CNT) << 36;
+	}
+
+	perf_ibs_event_update(perf_ibs, event, config);
 	perf_sample_data_init(&data, 0);
+	data.period = event->hw.last_period;
+
 	if (event->attr.sample_type & PERF_SAMPLE_RAW) {
 		ibs_data.caps = ibs_caps;
 		size = 1;
@@ -405,19 +419,6 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
 
 	regs = *iregs; /* XXX: update ip from ibs sample */
 
-	/*
-	 * Emulate IbsOpCurCnt in MSRC001_1033 (IbsOpCtl), not
-	 * supported in all cpus. As this triggered an interrupt, we
-	 * set the current count to the max count.
-	 */
-	config = ibs_data.regs[0];
-	if (perf_ibs == &perf_ibs_op && !(ibs_caps & IBS_CAPS_RDWROPCNT)) {
-		config &= ~IBS_OP_CUR_CNT;
-		config |= (config & IBS_OP_MAX_CNT) << 36;
-	}
-
-	perf_ibs_event_update(perf_ibs, event, config);
-
 	overflow = perf_ibs_set_period(perf_ibs, hwc, &config);
 	reenable = !(overflow && perf_event_overflow(event, &data, &regs));
 	config = (config >> 4) | (reenable ? perf_ibs->enable_mask : 0);