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