Root/drivers/oprofile/oprofile_perf.c

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 super_block *sb, 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(sb, root, buf);
151        oprofilefs_create_ulong(sb, dir, "enabled", &counter_config[i].enabled);
152        oprofilefs_create_ulong(sb, dir, "event", &counter_config[i].event);
153        oprofilefs_create_ulong(sb, dir, "count", &counter_config[i].count);
154        oprofilefs_create_ulong(sb, dir, "unit_mask", &counter_config[i].unit_mask);
155        oprofilefs_create_ulong(sb, dir, "kernel", &counter_config[i].kernel);
156        oprofilefs_create_ulong(sb, 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

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