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2024-02-20 e636c8d336489bf3eed5878299e6cc045bbad077 
 kernel/drivers/hwtracing/coresight/coresight-etm-perf.c
....@@ -24,20 +24,67 @@
2424 static struct pmu etm_pmu;
2525 static bool etm_perf_up;
2626 
27
-static DEFINE_PER_CPU(struct perf_output_handle, ctx_handle);
27
+/*
28
+ * An ETM context for a running event includes the perf aux handle
29
+ * and aux_data. For ETM, the aux_data (etm_event_data), consists of
30
+ * the trace path and the sink configuration. The event data is accessible
31
+ * via perf_get_aux(handle). However, a sink could "end" a perf output
32
+ * handle via the IRQ handler. And if the "sink" encounters a failure
33
+ * to "begin" another session (e.g due to lack of space in the buffer),
34
+ * the handle will be cleared. Thus, the event_data may not be accessible
35
+ * from the handle when we get to the etm_event_stop(), which is required
36
+ * for stopping the trace path. The event_data is guaranteed to stay alive
37
+ * until "free_aux()", which cannot happen as long as the event is active on
38
+ * the ETM. Thus the event_data for the session must be part of the ETM context
39
+ * to make sure we can disable the trace path.
40
+ */
41
+struct etm_ctxt {
42
+	struct perf_output_handle handle;
43
+	struct etm_event_data *event_data;
44
+};
45
+
46
+static DEFINE_PER_CPU(struct etm_ctxt, etm_ctxt);
2847 static DEFINE_PER_CPU(struct coresight_device *, csdev_src);
2948 
30
-/* ETMv3.5/PTM's ETMCR is 'config' */
49
+/*
50
+ * The PMU formats were orignally for ETMv3.5/PTM's ETMCR 'config';
51
+ * now take them as general formats and apply on all ETMs.
52
+ */
3153 PMU_FORMAT_ATTR(cycacc,		"config:" __stringify(ETM_OPT_CYCACC));
32
-PMU_FORMAT_ATTR(contextid,	"config:" __stringify(ETM_OPT_CTXTID));
54
+/* contextid1 enables tracing CONTEXTIDR_EL1 for ETMv4 */
55
+PMU_FORMAT_ATTR(contextid1,	"config:" __stringify(ETM_OPT_CTXTID));
56
+/* contextid2 enables tracing CONTEXTIDR_EL2 for ETMv4 */
57
+PMU_FORMAT_ATTR(contextid2,	"config:" __stringify(ETM_OPT_CTXTID2));
3358 PMU_FORMAT_ATTR(timestamp,	"config:" __stringify(ETM_OPT_TS));
3459 PMU_FORMAT_ATTR(retstack,	"config:" __stringify(ETM_OPT_RETSTK));
3560 /* Sink ID - same for all ETMs */
3661 PMU_FORMAT_ATTR(sinkid,		"config2:0-31");
3762 
63
+/*
64
+ * contextid always traces the "PID".  The PID is in CONTEXTIDR_EL1
65
+ * when the kernel is running at EL1; when the kernel is at EL2,
66
+ * the PID is in CONTEXTIDR_EL2.
67
+ */
68
+static ssize_t format_attr_contextid_show(struct device *dev,
69
+					  struct device_attribute *attr,
70
+					  char *page)
71
+{
72
+	int pid_fmt = ETM_OPT_CTXTID;
73
+
74
+#if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM4X)
75
+	pid_fmt = is_kernel_in_hyp_mode() ? ETM_OPT_CTXTID2 : ETM_OPT_CTXTID;
76
+#endif
77
+	return sprintf(page, "config:%d\n", pid_fmt);
78
+}
79
+
80
+struct device_attribute format_attr_contextid =
81
+	__ATTR(contextid, 0444, format_attr_contextid_show, NULL);
82
+
3883 static struct attribute *etm_config_formats_attr[] = {
3984 	&format_attr_cycacc.attr,
4085 	&format_attr_contextid.attr,
86
+	&format_attr_contextid1.attr,
87
+	&format_attr_contextid2.attr,
4188 	&format_attr_timestamp.attr,
4289 	&format_attr_retstack.attr,
4390 	&format_attr_sinkid.attr,
....@@ -204,13 +251,33 @@
204251 	schedule_work(&event_data->work);
205252 }
206253 
254
+/*
255
+ * Check if two given sinks are compatible with each other,
256
+ * so that they can use the same sink buffers, when an event
257
+ * moves around.
258
+ */
259
+static bool sinks_compatible(struct coresight_device *a,
260
+			     struct coresight_device *b)
261
+{
262
+	if (!a || !b)
263
+		return false;
264
+	/*
265
+	 * If the sinks are of the same subtype and driven
266
+	 * by the same driver, we can use the same buffer
267
+	 * on these sinks.
268
+	 */
269
+	return (a->subtype.sink_subtype == b->subtype.sink_subtype) &&
270
+	       (sink_ops(a) == sink_ops(b));
271
+}
272
+
207273 static void *etm_setup_aux(struct perf_event *event, void **pages,
208274 			   int nr_pages, bool overwrite)
209275 {
210276 	u32 id;
211277 	int cpu = event->cpu;
212278 	cpumask_t *mask;
213
-	struct coresight_device *sink;
279
+	struct coresight_device *sink = NULL;
280
+	struct coresight_device *user_sink = NULL, *last_sink = NULL;
214281 	struct etm_event_data *event_data = NULL;
215282 
216283 	event_data = alloc_event_data(cpu);
....@@ -221,13 +288,8 @@
221288 	/* First get the selected sink from user space. */
222289 	if (event->attr.config2) {
223290 		id = (u32)event->attr.config2;
224
-		sink = coresight_get_sink_by_id(id);
225
-	} else {
226
-		sink = coresight_get_enabled_sink(true);
291
+		sink = user_sink = coresight_get_sink_by_id(id);
227292 	}
228
-
229
-	if (!sink)
230
-		goto err;
231293 
232294 	mask = &event_data->mask;
233295 
....@@ -254,6 +316,35 @@
254316 		}
255317 
256318 		/*
319
+		 * No sink provided - look for a default sink for all the ETMs,
320
+		 * where this event can be scheduled.
321
+		 * We allocate the sink specific buffers only once for this
322
+		 * event. If the ETMs have different default sink devices, we
323
+		 * can only use a single "type" of sink as the event can carry
324
+		 * only one sink specific buffer. Thus we have to make sure
325
+		 * that the sinks are of the same type and driven by the same
326
+		 * driver, as the one we allocate the buffer for. As such
327
+		 * we choose the first sink and check if the remaining ETMs
328
+		 * have a compatible default sink. We don't trace on a CPU
329
+		 * if the sink is not compatible.
330
+		 */
331
+		if (!user_sink) {
332
+			/* Find the default sink for this ETM */
333
+			sink = coresight_find_default_sink(csdev);
334
+			if (!sink) {
335
+				cpumask_clear_cpu(cpu, mask);
336
+				continue;
337
+			}
338
+
339
+			/* Check if this sink compatible with the last sink */
340
+			if (last_sink && !sinks_compatible(last_sink, sink)) {
341
+				cpumask_clear_cpu(cpu, mask);
342
+				continue;
343
+			}
344
+			last_sink = sink;
345
+		}
346
+
347
+		/*
257348 		 * Building a path doesn't enable it, it simply builds a
258349 		 * list of devices from source to sink that can be
259350 		 * referenced later when the path is actually needed.
....@@ -267,6 +358,10 @@
267358 		*etm_event_cpu_path_ptr(event_data, cpu) = path;
268359 	}
269360 
361
+	/* no sink found for any CPU - cannot trace */
362
+	if (!sink)
363
+		goto err;
364
+
270365 	/* If we don't have any CPUs ready for tracing, abort */
271366 	cpu = cpumask_first(mask);
272367 	if (cpu >= nr_cpu_ids)
....@@ -275,7 +370,12 @@
275370 	if (!sink_ops(sink)->alloc_buffer || !sink_ops(sink)->free_buffer)
276371 		goto err;
277372 
278
-	/* Allocate the sink buffer for this session */
373
+	/*
374
+	 * Allocate the sink buffer for this session. All the sinks
375
+	 * where this event can be scheduled are ensured to be of the
376
+	 * same type. Thus the same sink configuration is used by the
377
+	 * sinks.
378
+	 */
279379 	event_data->snk_config =
280380 			sink_ops(sink)->alloc_buffer(sink, event, pages,
281381 						     nr_pages, overwrite);
....@@ -295,11 +395,16 @@
295395 {
296396 	int cpu = smp_processor_id();
297397 	struct etm_event_data *event_data;
298
-	struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle);
398
+	struct etm_ctxt *ctxt = this_cpu_ptr(&etm_ctxt);
399
+	struct perf_output_handle *handle = &ctxt->handle;
299400 	struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
300401 	struct list_head *path;
301402 
302403 	if (!csdev)
404
+		goto fail;
405
+
406
+	/* Have we messed up our tracking ? */
407
+	if (WARN_ON(ctxt->event_data))
303408 		goto fail;
304409 
305410 	/*
....@@ -337,6 +442,8 @@
337442 	if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF))
338443 		goto fail_disable_path;
339444 
445
+	/* Save the event_data for this ETM */
446
+	ctxt->event_data = event_data;
340447 out:
341448 	return;
342449 
....@@ -355,11 +462,28 @@
355462 	int cpu = smp_processor_id();
356463 	unsigned long size;
357464 	struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
358
-	struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle);
359
-	struct etm_event_data *event_data = perf_get_aux(handle);
465
+	struct etm_ctxt *ctxt = this_cpu_ptr(&etm_ctxt);
466
+	struct perf_output_handle *handle = &ctxt->handle;
467
+	struct etm_event_data *event_data;
360468 	struct list_head *path;
361469 
470
+	/*
471
+	 * If we still have access to the event_data via handle,
472
+	 * confirm that we haven't messed up the tracking.
473
+	 */
474
+	if (handle->event &&
475
+	    WARN_ON(perf_get_aux(handle) != ctxt->event_data))
476
+		return;
477
+
478
+	event_data = ctxt->event_data;
479
+	/* Clear the event_data as this ETM is stopping the trace. */
480
+	ctxt->event_data = NULL;
481
+
362482 	if (event->hw.state == PERF_HES_STOPPED)
483
+		return;
484
+
485
+	/* We must have a valid event_data for a running event */
486
+	if (WARN_ON(!event_data))
363487 		return;
364488 
365489 	if (!csdev)
....@@ -379,7 +503,13 @@
379503 	/* tell the core */
380504 	event->hw.state = PERF_HES_STOPPED;
381505 
382
-	if (mode & PERF_EF_UPDATE) {
506
+	/*
507
+	 * If the handle is not bound to an event anymore
508
+	 * (e.g, the sink driver was unable to restart the
509
+	 * handle due to lack of buffer space), we don't
510
+	 * have to do anything here.
511
+	 */
512
+	if (handle->event && (mode & PERF_EF_UPDATE)) {
383513 		if (WARN_ON_ONCE(handle->event != event))
384514 			return;
385515 
....@@ -516,6 +646,7 @@
516646 
517647 	return 0;
518648 }
649
+EXPORT_SYMBOL_GPL(etm_perf_symlink);
519650 
520651 static ssize_t etm_perf_sink_name_show(struct device *dev,
521652 				       struct device_attribute *dattr,
....@@ -589,7 +720,7 @@
589720 	csdev->ea = NULL;
590721 }
591722 
592
-static int __init etm_perf_init(void)
723
+int __init etm_perf_init(void)
593724 {
594725 	int ret;
595726 
....@@ -609,6 +740,7 @@
609740 	etm_pmu.addr_filters_sync	= etm_addr_filters_sync;
610741 	etm_pmu.addr_filters_validate	= etm_addr_filters_validate;
611742 	etm_pmu.nr_addr_filters		= ETM_ADDR_CMP_MAX;
743
+	etm_pmu.module			= THIS_MODULE;
612744 
613745 	ret = perf_pmu_register(&etm_pmu, CORESIGHT_ETM_PMU_NAME, -1);
614746 	if (ret == 0)
....@@ -616,4 +748,8 @@
616748 
617749 	return ret;
618750 }
619
-device_initcall(etm_perf_init);
751
+
752
+void __exit etm_perf_exit(void)
753
+{
754
+	perf_pmu_unregister(&etm_pmu);
755
+}