1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright 2010 ARM Ltd.
  4 * Copyright 2012 Advanced Micro Devices, Inc., Robert Richter
  5 *
  6 * Perf-events backend for OProfile.
  7 */
  8#include <linux/perf_event.h>
  9#include <linux/platform_device.h>
 10#include <linux/oprofile.h>
 11#include <linux/slab.h>
 12
 13/*
 14 * Per performance monitor configuration as set via oprofilefs.
 15 */
 16struct op_counter_config {
 17	unsigned long count;
 18	unsigned long enabled;
 19	unsigned long event;
 20	unsigned long unit_mask;
 21	unsigned long kernel;
 22	unsigned long user;
 23	struct perf_event_attr attr;
 24};
 25
 26static int oprofile_perf_enabled;
 27static DEFINE_MUTEX(oprofile_perf_mutex);
 28
 29static struct op_counter_config *counter_config;
 30static DEFINE_PER_CPU(struct perf_event **, perf_events);
 31static int num_counters;
 32
 33/*
 34 * Overflow callback for oprofile.
 35 */
 36static void op_overflow_handler(struct perf_event *event,
 37			struct perf_sample_data *data, struct pt_regs *regs)
 38{
 39	int id;
 40	u32 cpu = smp_processor_id();
 41
 42	for (id = 0; id < num_counters; ++id)
 43		if (per_cpu(perf_events, cpu)[id] == event)
 44			break;
 45
 46	if (id != num_counters)
 47		oprofile_add_sample(regs, id);
 48	else
 49		pr_warning("oprofile: ignoring spurious overflow "
 50				"on cpu %u\n", cpu);
 51}
 52
 53/*
 54 * Called by oprofile_perf_setup to create perf attributes to mirror the oprofile
 55 * settings in counter_config. Attributes are created as `pinned' events and
 56 * so are permanently scheduled on the PMU.
 57 */
 58static void op_perf_setup(void)
 59{
 60	int i;
 61	u32 size = sizeof(struct perf_event_attr);
 62	struct perf_event_attr *attr;
 63
 64	for (i = 0; i < num_counters; ++i) {
 65		attr = &counter_config[i].attr;
 66		memset(attr, 0, size);
 67		attr->type		= PERF_TYPE_RAW;
 68		attr->size		= size;
 69		attr->config		= counter_config[i].event;
 70		attr->sample_period	= counter_config[i].count;
 71		attr->pinned		= 1;
 72	}
 73}
 74
 75static int op_create_counter(int cpu, int event)
 76{
 77	struct perf_event *pevent;
 78
 79	if (!counter_config[event].enabled || per_cpu(perf_events, cpu)[event])
 80		return 0;
 81
 82	pevent = perf_event_create_kernel_counter(&counter_config[event].attr,
 83						  cpu, NULL,
 84						  op_overflow_handler, NULL);
 85
 86	if (IS_ERR(pevent))
 87		return PTR_ERR(pevent);
 88
 89	if (pevent->state != PERF_EVENT_STATE_ACTIVE) {
 90		perf_event_release_kernel(pevent);
 91		pr_warning("oprofile: failed to enable event %d "
 92				"on CPU %d\n", event, cpu);
 93		return -EBUSY;
 94	}
 95
 96	per_cpu(perf_events, cpu)[event] = pevent;
 97
 98	return 0;
 99}
100
101static void op_destroy_counter(int cpu, int event)
102{
103	struct perf_event *pevent = per_cpu(perf_events, cpu)[event];
104
105	if (pevent) {
106		perf_event_release_kernel(pevent);
107		per_cpu(perf_events, cpu)[event] = NULL;
108	}
109}
110
111/*
112 * Called by oprofile_perf_start to create active perf events based on the
113 * perviously configured attributes.
114 */
115static int op_perf_start(void)
116{
117	int cpu, event, ret = 0;
118
119	for_each_online_cpu(cpu) {
120		for (event = 0; event < num_counters; ++event) {
121			ret = op_create_counter(cpu, event);
122			if (ret)
123				return ret;
124		}
125	}
126
127	return ret;
128}
129
130/*
131 * Called by oprofile_perf_stop at the end of a profiling run.
132 */
133static void op_perf_stop(void)
134{
135	int cpu, event;
136
137	for_each_online_cpu(cpu)
138		for (event = 0; event < num_counters; ++event)
139			op_destroy_counter(cpu, event);
140}
141
142static int oprofile_perf_create_files(struct dentry *root)
143{
144	unsigned int i;
145
146	for (i = 0; i < num_counters; i++) {
147		struct dentry *dir;
148		char buf[4];
149
150		snprintf(buf, sizeof buf, "%d", i);
151		dir = oprofilefs_mkdir(root, buf);
152		oprofilefs_create_ulong(dir, "enabled", &counter_config[i].enabled);
153		oprofilefs_create_ulong(dir, "event", &counter_config[i].event);
154		oprofilefs_create_ulong(dir, "count", &counter_config[i].count);
155		oprofilefs_create_ulong(dir, "unit_mask", &counter_config[i].unit_mask);
156		oprofilefs_create_ulong(dir, "kernel", &counter_config[i].kernel);
157		oprofilefs_create_ulong(dir, "user", &counter_config[i].user);
158	}
159
160	return 0;
161}
162
163static int oprofile_perf_setup(void)
164{
165	raw_spin_lock(&oprofilefs_lock);
166	op_perf_setup();
167	raw_spin_unlock(&oprofilefs_lock);
168	return 0;
169}
170
171static int oprofile_perf_start(void)
172{
173	int ret = -EBUSY;
174
175	mutex_lock(&oprofile_perf_mutex);
176	if (!oprofile_perf_enabled) {
177		ret = 0;
178		op_perf_start();
179		oprofile_perf_enabled = 1;
180	}
181	mutex_unlock(&oprofile_perf_mutex);
182	return ret;
183}
184
185static void oprofile_perf_stop(void)
186{
187	mutex_lock(&oprofile_perf_mutex);
188	if (oprofile_perf_enabled)
189		op_perf_stop();
190	oprofile_perf_enabled = 0;
191	mutex_unlock(&oprofile_perf_mutex);
192}
193
194#ifdef CONFIG_PM
195
196static int oprofile_perf_suspend(struct platform_device *dev, pm_message_t state)
197{
198	mutex_lock(&oprofile_perf_mutex);
199	if (oprofile_perf_enabled)
200		op_perf_stop();
201	mutex_unlock(&oprofile_perf_mutex);
202	return 0;
203}
204
205static int oprofile_perf_resume(struct platform_device *dev)
206{
207	mutex_lock(&oprofile_perf_mutex);
208	if (oprofile_perf_enabled && op_perf_start())
209		oprofile_perf_enabled = 0;
210	mutex_unlock(&oprofile_perf_mutex);
211	return 0;
212}
213
214static struct platform_driver oprofile_driver = {
215	.driver		= {
216		.name		= "oprofile-perf",
217	},
218	.resume		= oprofile_perf_resume,
219	.suspend	= oprofile_perf_suspend,
220};
221
222static struct platform_device *oprofile_pdev;
223
224static int __init init_driverfs(void)
225{
226	int ret;
227
228	ret = platform_driver_register(&oprofile_driver);
229	if (ret)
230		return ret;
231
232	oprofile_pdev =	platform_device_register_simple(
233				oprofile_driver.driver.name, 0, NULL, 0);
234	if (IS_ERR(oprofile_pdev)) {
235		ret = PTR_ERR(oprofile_pdev);
236		platform_driver_unregister(&oprofile_driver);
237	}
238
239	return ret;
240}
241
242static void exit_driverfs(void)
243{
244	platform_device_unregister(oprofile_pdev);
245	platform_driver_unregister(&oprofile_driver);
246}
247
248#else
249
250static inline int  init_driverfs(void) { return 0; }
251static inline void exit_driverfs(void) { }
252
253#endif /* CONFIG_PM */
254
255void oprofile_perf_exit(void)
256{
257	int cpu, id;
258	struct perf_event *event;
259
260	for_each_possible_cpu(cpu) {
261		for (id = 0; id < num_counters; ++id) {
262			event = per_cpu(perf_events, cpu)[id];
263			if (event)
264				perf_event_release_kernel(event);
265		}
266
267		kfree(per_cpu(perf_events, cpu));
268	}
269
270	kfree(counter_config);
271	exit_driverfs();
272}
273
274int __init oprofile_perf_init(struct oprofile_operations *ops)
275{
276	int cpu, ret = 0;
277
278	ret = init_driverfs();
279	if (ret)
280		return ret;
281
282	num_counters = perf_num_counters();
283	if (num_counters <= 0) {
284		pr_info("oprofile: no performance counters\n");
285		ret = -ENODEV;
286		goto out;
287	}
288
289	counter_config = kcalloc(num_counters,
290			sizeof(struct op_counter_config), GFP_KERNEL);
291
292	if (!counter_config) {
293		pr_info("oprofile: failed to allocate %d "
294				"counters\n", num_counters);
295		ret = -ENOMEM;
296		num_counters = 0;
297		goto out;
298	}
299
300	for_each_possible_cpu(cpu) {
301		per_cpu(perf_events, cpu) = kcalloc(num_counters,
302				sizeof(struct perf_event *), GFP_KERNEL);
303		if (!per_cpu(perf_events, cpu)) {
304			pr_info("oprofile: failed to allocate %d perf events "
305					"for cpu %d\n", num_counters, cpu);
306			ret = -ENOMEM;
307			goto out;
308		}
309	}
310
311	ops->create_files	= oprofile_perf_create_files;
312	ops->setup		= oprofile_perf_setup;
313	ops->start		= oprofile_perf_start;
314	ops->stop		= oprofile_perf_stop;
315	ops->shutdown		= oprofile_perf_stop;
316	ops->cpu_type		= op_name_from_perf_id();
317
318	if (!ops->cpu_type)
319		ret = -ENODEV;
320	else
321		pr_info("oprofile: using %s\n", ops->cpu_type);
322
323out:
324	if (ret)
325		oprofile_perf_exit();
326
327	return ret;
328}