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 */
15 struct 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
25 static int oprofile_perf_enabled;
26 static DEFINE_MUTEX(oprofile_perf_mutex);
27
28 static struct op_counter_config *counter_config;
29 static DEFINE_PER_CPU(struct perf_event **, perf_events);
30 static int num_counters;
31
32 /*
33 * Overflow callback for oprofile.
34 */
op_overflow_handler(struct perf_event * event,struct perf_sample_data * data,struct pt_regs * regs)35 static 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 */
op_perf_setup(void)57 static 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
op_create_counter(int cpu,int event)74 static 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
op_destroy_counter(int cpu,int event)100 static 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 */
op_perf_start(void)114 static 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 */
op_perf_stop(void)132 static 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
oprofile_perf_create_files(struct dentry * root)141 static 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
oprofile_perf_setup(void)162 static 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
oprofile_perf_start(void)170 static 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
oprofile_perf_stop(void)184 static 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
oprofile_perf_suspend(struct platform_device * dev,pm_message_t state)195 static 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
oprofile_perf_resume(struct platform_device * dev)204 static 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
213 static struct platform_driver oprofile_driver = {
214 .driver = {
215 .name = "oprofile-perf",
216 },
217 .resume = oprofile_perf_resume,
218 .suspend = oprofile_perf_suspend,
219 };
220
221 static struct platform_device *oprofile_pdev;
222
init_driverfs(void)223 static 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
exit_driverfs(void)241 static void exit_driverfs(void)
242 {
243 platform_device_unregister(oprofile_pdev);
244 platform_driver_unregister(&oprofile_driver);
245 }
246
247 #else
248
init_driverfs(void)249 static inline int init_driverfs(void) { return 0; }
exit_driverfs(void)250 static inline void exit_driverfs(void) { }
251
252 #endif /* CONFIG_PM */
253
oprofile_perf_exit(void)254 void 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
oprofile_perf_init(struct oprofile_operations * ops)273 int __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
322 out:
323 if (ret)
324 oprofile_perf_exit();
325
326 return ret;
327 }
328