1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Performance event support framework for SuperH hardware counters.
4 *
5 * Copyright (C) 2009 Paul Mundt
6 *
7 * Heavily based on the x86 and PowerPC implementations.
8 *
9 * x86:
10 * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
11 * Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
12 * Copyright (C) 2009 Jaswinder Singh Rajput
13 * Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
14 * Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra
15 * Copyright (C) 2009 Intel Corporation, <markus.t.metzger@intel.com>
16 *
17 * ppc:
18 * Copyright 2008-2009 Paul Mackerras, IBM Corporation.
19 */
20 #include <linux/kernel.h>
21 #include <linux/init.h>
22 #include <linux/io.h>
23 #include <linux/irq.h>
24 #include <linux/perf_event.h>
25 #include <linux/export.h>
26 #include <asm/processor.h>
27
28 struct cpu_hw_events {
29 struct perf_event *events[MAX_HWEVENTS];
30 unsigned long used_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
31 unsigned long active_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
32 };
33
34 DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
35
36 static struct sh_pmu *sh_pmu __read_mostly;
37
38 /* Number of perf_events counting hardware events */
39 static atomic_t num_events;
40 /* Used to avoid races in calling reserve/release_pmc_hardware */
41 static DEFINE_MUTEX(pmc_reserve_mutex);
42
43 /*
44 * Stub these out for now, do something more profound later.
45 */
46 int reserve_pmc_hardware(void)
47 {
48 return 0;
49 }
50
51 void release_pmc_hardware(void)
52 {
53 }
54
55 static inline int sh_pmu_initialized(void)
56 {
57 return !!sh_pmu;
58 }
59
60 /*
61 * Release the PMU if this is the last perf_event.
62 */
63 static void hw_perf_event_destroy(struct perf_event *event)
64 {
65 if (!atomic_add_unless(&num_events, -1, 1)) {
66 mutex_lock(&pmc_reserve_mutex);
67 if (atomic_dec_return(&num_events) == 0)
68 release_pmc_hardware();
69 mutex_unlock(&pmc_reserve_mutex);
70 }
71 }
72
73 static int hw_perf_cache_event(int config, int *evp)
74 {
75 unsigned long type, op, result;
76 int ev;
77
78 if (!sh_pmu->cache_events)
79 return -EINVAL;
80
81 /* unpack config */
82 type = config & 0xff;
83 op = (config >> 8) & 0xff;
84 result = (config >> 16) & 0xff;
85
86 if (type >= PERF_COUNT_HW_CACHE_MAX ||
87 op >= PERF_COUNT_HW_CACHE_OP_MAX ||
88 result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
89 return -EINVAL;
90
91 ev = (*sh_pmu->cache_events)[type][op][result];
92 if (ev == 0)
93 return -EOPNOTSUPP;
94 if (ev == -1)
95 return -EINVAL;
96 *evp = ev;
97 return 0;
98 }
99
100 static int __hw_perf_event_init(struct perf_event *event)
101 {
102 struct perf_event_attr *attr = &event->attr;
103 struct hw_perf_event *hwc = &event->hw;
104 int config = -1;
105 int err;
106
107 if (!sh_pmu_initialized())
108 return -ENODEV;
109
110 /*
111 * See if we need to reserve the counter.
112 *
113 * If no events are currently in use, then we have to take a
114 * mutex to ensure that we don't race with another task doing
115 * reserve_pmc_hardware or release_pmc_hardware.
116 */
117 err = 0;
118 if (!atomic_inc_not_zero(&num_events)) {
119 mutex_lock(&pmc_reserve_mutex);
120 if (atomic_read(&num_events) == 0 &&
121 reserve_pmc_hardware())
122 err = -EBUSY;
123 else
124 atomic_inc(&num_events);
125 mutex_unlock(&pmc_reserve_mutex);
126 }
127
128 if (err)
129 return err;
130
131 event->destroy = hw_perf_event_destroy;
132
133 switch (attr->type) {
134 case PERF_TYPE_RAW:
135 config = attr->config & sh_pmu->raw_event_mask;
136 break;
137 case PERF_TYPE_HW_CACHE:
138 err = hw_perf_cache_event(attr->config, &config);
139 if (err)
140 return err;
141 break;
142 case PERF_TYPE_HARDWARE:
143 if (attr->config >= sh_pmu->max_events)
144 return -EINVAL;
145
146 config = sh_pmu->event_map(attr->config);
147 break;
148 }
149
150 if (config == -1)
151 return -EINVAL;
152
153 hwc->config |= config;
154
155 return 0;
156 }
157
158 static void sh_perf_event_update(struct perf_event *event,
159 struct hw_perf_event *hwc, int idx)
160 {
161 u64 prev_raw_count, new_raw_count;
162 s64 delta;
163 int shift = 0;
164
165 /*
166 * Depending on the counter configuration, they may or may not
167 * be chained, in which case the previous counter value can be
168 * updated underneath us if the lower-half overflows.
169 *
170 * Our tactic to handle this is to first atomically read and
171 * exchange a new raw count - then add that new-prev delta
172 * count to the generic counter atomically.
173 *
174 * As there is no interrupt associated with the overflow events,
175 * this is the simplest approach for maintaining consistency.
176 */
177 again:
178 prev_raw_count = local64_read(&hwc->prev_count);
179 new_raw_count = sh_pmu->read(idx);
180
181 if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
182 new_raw_count) != prev_raw_count)
183 goto again;
184
185 /*
186 * Now we have the new raw value and have updated the prev
187 * timestamp already. We can now calculate the elapsed delta
188 * (counter-)time and add that to the generic counter.
189 *
190 * Careful, not all hw sign-extends above the physical width
191 * of the count.
192 */
193 delta = (new_raw_count << shift) - (prev_raw_count << shift);
194 delta >>= shift;
195
196 local64_add(delta, &event->count);
197 }
198
199 static void sh_pmu_stop(struct perf_event *event, int flags)
200 {
201 struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
202 struct hw_perf_event *hwc = &event->hw;
203 int idx = hwc->idx;
204
205 if (!(event->hw.state & PERF_HES_STOPPED)) {
206 sh_pmu->disable(hwc, idx);
207 cpuc->events[idx] = NULL;
208 event->hw.state |= PERF_HES_STOPPED;
209 }
210
211 if ((flags & PERF_EF_UPDATE) && !(event->hw.state & PERF_HES_UPTODATE)) {
212 sh_perf_event_update(event, &event->hw, idx);
213 event->hw.state |= PERF_HES_UPTODATE;
214 }
215 }
216
217 static void sh_pmu_start(struct perf_event *event, int flags)
218 {
219 struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
220 struct hw_perf_event *hwc = &event->hw;
221 int idx = hwc->idx;
222
223 if (WARN_ON_ONCE(idx == -1))
224 return;
225
226 if (flags & PERF_EF_RELOAD)
227 WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
228
229 cpuc->events[idx] = event;
230 event->hw.state = 0;
231 sh_pmu->enable(hwc, idx);
232 }
233
234 static void sh_pmu_del(struct perf_event *event, int flags)
235 {
236 struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
237
238 sh_pmu_stop(event, PERF_EF_UPDATE);
239 __clear_bit(event->hw.idx, cpuc->used_mask);
240
241 perf_event_update_userpage(event);
242 }
243
244 static int sh_pmu_add(struct perf_event *event, int flags)
245 {
246 struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
247 struct hw_perf_event *hwc = &event->hw;
248 int idx = hwc->idx;
249 int ret = -EAGAIN;
250
251 perf_pmu_disable(event->pmu);
252
253 if (__test_and_set_bit(idx, cpuc->used_mask)) {
254 idx = find_first_zero_bit(cpuc->used_mask, sh_pmu->num_events);
255 if (idx == sh_pmu->num_events)
256 goto out;
257
258 __set_bit(idx, cpuc->used_mask);
259 hwc->idx = idx;
260 }
261
262 sh_pmu->disable(hwc, idx);
263
264 event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
265 if (flags & PERF_EF_START)
266 sh_pmu_start(event, PERF_EF_RELOAD);
267
268 perf_event_update_userpage(event);
269 ret = 0;
270 out:
271 perf_pmu_enable(event->pmu);
272 return ret;
273 }
274
275 static void sh_pmu_read(struct perf_event *event)
276 {
277 sh_perf_event_update(event, &event->hw, event->hw.idx);
278 }
279
280 static int sh_pmu_event_init(struct perf_event *event)
281 {
282 int err;
283
284 /* does not support taken branch sampling */
285 if (has_branch_stack(event))
286 return -EOPNOTSUPP;
287
288 switch (event->attr.type) {
289 case PERF_TYPE_RAW:
290 case PERF_TYPE_HW_CACHE:
291 case PERF_TYPE_HARDWARE:
292 err = __hw_perf_event_init(event);
293 break;
294
295 default:
296 return -ENOENT;
297 }
298
299 if (unlikely(err)) {
300 if (event->destroy)
301 event->destroy(event);
302 }
303
304 return err;
305 }
306
307 static void sh_pmu_enable(struct pmu *pmu)
308 {
309 if (!sh_pmu_initialized())
310 return;
311
312 sh_pmu->enable_all();
313 }
314
315 static void sh_pmu_disable(struct pmu *pmu)
316 {
317 if (!sh_pmu_initialized())
318 return;
319
320 sh_pmu->disable_all();
321 }
322
323 static struct pmu pmu = {
324 .pmu_enable = sh_pmu_enable,
325 .pmu_disable = sh_pmu_disable,
326 .event_init = sh_pmu_event_init,
327 .add = sh_pmu_add,
328 .del = sh_pmu_del,
329 .start = sh_pmu_start,
330 .stop = sh_pmu_stop,
331 .read = sh_pmu_read,
332 };
333
334 static int sh_pmu_prepare_cpu(unsigned int cpu)
335 {
336 struct cpu_hw_events *cpuhw = &per_cpu(cpu_hw_events, cpu);
337
338 memset(cpuhw, 0, sizeof(struct cpu_hw_events));
339 return 0;
340 }
341
342 int register_sh_pmu(struct sh_pmu *_pmu)
343 {
344 if (sh_pmu)
345 return -EBUSY;
346 sh_pmu = _pmu;
347
348 pr_info("Performance Events: %s support registered\n", _pmu->name);
349
350 /*
351 * All of the on-chip counters are "limited", in that they have
352 * no interrupts, and are therefore unable to do sampling without
353 * further work and timer assistance.
354 */
355 pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
356
357 WARN_ON(_pmu->num_events > MAX_HWEVENTS);
358
359 perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
360 cpuhp_setup_state(CPUHP_PERF_SUPERH, "PERF_SUPERH", sh_pmu_prepare_cpu,
361 NULL);
362 return 0;
363 }
364
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