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469eb32e | 1 | // SPDX-License-Identifier: GPL-2.0+ |
62a038d3 | 2 | /* |
62a038d3 P |
3 | * Copyright (C) 2007 Alan Stern |
4 | * Copyright (C) IBM Corporation, 2009 | |
24f1e32c | 5 | * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com> |
ba1c813a FW |
6 | * |
7 | * Thanks to Ingo Molnar for his many suggestions. | |
ba6909b7 P |
8 | * |
9 | * Authors: Alan Stern <stern@rowland.harvard.edu> | |
10 | * K.Prasad <prasad@linux.vnet.ibm.com> | |
11 | * Frederic Weisbecker <fweisbec@gmail.com> | |
62a038d3 P |
12 | */ |
13 | ||
14 | /* | |
15 | * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, | |
16 | * using the CPU's debug registers. | |
17 | * This file contains the arch-independent routines. | |
18 | */ | |
19 | ||
20 | #include <linux/irqflags.h> | |
21 | #include <linux/kallsyms.h> | |
22 | #include <linux/notifier.h> | |
23 | #include <linux/kprobes.h> | |
24 | #include <linux/kdebug.h> | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/percpu.h> | |
28 | #include <linux/sched.h> | |
29 | #include <linux/init.h> | |
feef47d0 | 30 | #include <linux/slab.h> |
45a73372 | 31 | #include <linux/list.h> |
88f7a890 | 32 | #include <linux/cpu.h> |
62a038d3 | 33 | #include <linux/smp.h> |
ea6a9d53 | 34 | #include <linux/bug.h> |
62a038d3 | 35 | |
24f1e32c | 36 | #include <linux/hw_breakpoint.h> |
ba1c813a FW |
37 | /* |
38 | * Constraints data | |
39 | */ | |
bde96030 ON |
40 | struct bp_cpuinfo { |
41 | /* Number of pinned cpu breakpoints in a cpu */ | |
42 | unsigned int cpu_pinned; | |
43 | /* tsk_pinned[n] is the number of tasks having n+1 breakpoints */ | |
44 | unsigned int *tsk_pinned; | |
45 | /* Number of non-pinned cpu/task breakpoints in a cpu */ | |
46 | unsigned int flexible; /* XXX: placeholder, see fetch_this_slot() */ | |
47 | }; | |
62a038d3 | 48 | |
bde96030 | 49 | static DEFINE_PER_CPU(struct bp_cpuinfo, bp_cpuinfo[TYPE_MAX]); |
feef47d0 FW |
50 | static int nr_slots[TYPE_MAX]; |
51 | ||
bde96030 ON |
52 | static struct bp_cpuinfo *get_bp_info(int cpu, enum bp_type_idx type) |
53 | { | |
54 | return per_cpu_ptr(bp_cpuinfo + type, cpu); | |
55 | } | |
56 | ||
45a73372 FW |
57 | /* Keep track of the breakpoints attached to tasks */ |
58 | static LIST_HEAD(bp_task_head); | |
59 | ||
feef47d0 FW |
60 | static int constraints_initialized; |
61 | ||
ba1c813a FW |
62 | /* Gather the number of total pinned and un-pinned bp in a cpuset */ |
63 | struct bp_busy_slots { | |
64 | unsigned int pinned; | |
65 | unsigned int flexible; | |
66 | }; | |
67 | ||
68 | /* Serialize accesses to the above constraints */ | |
69 | static DEFINE_MUTEX(nr_bp_mutex); | |
70 | ||
f93a2054 FW |
71 | __weak int hw_breakpoint_weight(struct perf_event *bp) |
72 | { | |
73 | return 1; | |
74 | } | |
75 | ||
cbd9d9f1 | 76 | static inline enum bp_type_idx find_slot_idx(u64 bp_type) |
0102752e | 77 | { |
cbd9d9f1 | 78 | if (bp_type & HW_BREAKPOINT_RW) |
0102752e FW |
79 | return TYPE_DATA; |
80 | ||
81 | return TYPE_INST; | |
82 | } | |
83 | ||
ba1c813a FW |
84 | /* |
85 | * Report the maximum number of pinned breakpoints a task | |
86 | * have in this cpu | |
87 | */ | |
0102752e | 88 | static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type) |
62a038d3 | 89 | { |
bde96030 | 90 | unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned; |
ba1c813a | 91 | int i; |
62a038d3 | 92 | |
feef47d0 | 93 | for (i = nr_slots[type] - 1; i >= 0; i--) { |
ba1c813a FW |
94 | if (tsk_pinned[i] > 0) |
95 | return i + 1; | |
62a038d3 P |
96 | } |
97 | ||
24f1e32c | 98 | return 0; |
62a038d3 P |
99 | } |
100 | ||
45a73372 FW |
101 | /* |
102 | * Count the number of breakpoints of the same type and same task. | |
103 | * The given event must be not on the list. | |
104 | */ | |
0d855354 | 105 | static int task_bp_pinned(int cpu, struct perf_event *bp, enum bp_type_idx type) |
56053170 | 106 | { |
50f16a8b | 107 | struct task_struct *tsk = bp->hw.target; |
45a73372 | 108 | struct perf_event *iter; |
56053170 FW |
109 | int count = 0; |
110 | ||
45a73372 | 111 | list_for_each_entry(iter, &bp_task_head, hw.bp_list) { |
50f16a8b | 112 | if (iter->hw.target == tsk && |
cbd9d9f1 | 113 | find_slot_idx(iter->attr.bp_type) == type && |
8b4d801b | 114 | (iter->cpu < 0 || cpu == iter->cpu)) |
45a73372 | 115 | count += hw_breakpoint_weight(iter); |
56053170 FW |
116 | } |
117 | ||
56053170 FW |
118 | return count; |
119 | } | |
120 | ||
1c10adbb ON |
121 | static const struct cpumask *cpumask_of_bp(struct perf_event *bp) |
122 | { | |
123 | if (bp->cpu >= 0) | |
124 | return cpumask_of(bp->cpu); | |
125 | return cpu_possible_mask; | |
126 | } | |
127 | ||
ba1c813a FW |
128 | /* |
129 | * Report the number of pinned/un-pinned breakpoints we have in | |
130 | * a given cpu (cpu > -1) or in all of them (cpu = -1). | |
131 | */ | |
56053170 | 132 | static void |
0102752e FW |
133 | fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp, |
134 | enum bp_type_idx type) | |
ba1c813a | 135 | { |
1c10adbb ON |
136 | const struct cpumask *cpumask = cpumask_of_bp(bp); |
137 | int cpu; | |
56053170 | 138 | |
1c10adbb | 139 | for_each_cpu(cpu, cpumask) { |
bde96030 ON |
140 | struct bp_cpuinfo *info = get_bp_info(cpu, type); |
141 | int nr; | |
ba1c813a | 142 | |
bde96030 | 143 | nr = info->cpu_pinned; |
50f16a8b | 144 | if (!bp->hw.target) |
0102752e | 145 | nr += max_task_bp_pinned(cpu, type); |
56053170 | 146 | else |
0d855354 | 147 | nr += task_bp_pinned(cpu, bp, type); |
ba1c813a FW |
148 | |
149 | if (nr > slots->pinned) | |
150 | slots->pinned = nr; | |
151 | ||
bde96030 | 152 | nr = info->flexible; |
ba1c813a FW |
153 | if (nr > slots->flexible) |
154 | slots->flexible = nr; | |
155 | } | |
156 | } | |
157 | ||
f93a2054 FW |
158 | /* |
159 | * For now, continue to consider flexible as pinned, until we can | |
160 | * ensure no flexible event can ever be scheduled before a pinned event | |
161 | * in a same cpu. | |
162 | */ | |
163 | static void | |
164 | fetch_this_slot(struct bp_busy_slots *slots, int weight) | |
165 | { | |
166 | slots->pinned += weight; | |
167 | } | |
168 | ||
ba1c813a FW |
169 | /* |
170 | * Add a pinned breakpoint for the given task in our constraint table | |
171 | */ | |
7ab71f32 | 172 | static void toggle_bp_task_slot(struct perf_event *bp, int cpu, |
f93a2054 | 173 | enum bp_type_idx type, int weight) |
ba1c813a | 174 | { |
bde96030 | 175 | unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned; |
e1ebe862 ON |
176 | int old_idx, new_idx; |
177 | ||
178 | old_idx = task_bp_pinned(cpu, bp, type) - 1; | |
7ab71f32 | 179 | new_idx = old_idx + weight; |
e1ebe862 ON |
180 | |
181 | if (old_idx >= 0) | |
182 | tsk_pinned[old_idx]--; | |
183 | if (new_idx >= 0) | |
184 | tsk_pinned[new_idx]++; | |
ba1c813a FW |
185 | } |
186 | ||
187 | /* | |
188 | * Add/remove the given breakpoint in our constraint table | |
189 | */ | |
0102752e | 190 | static void |
f93a2054 FW |
191 | toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, |
192 | int weight) | |
ba1c813a | 193 | { |
1c10adbb ON |
194 | const struct cpumask *cpumask = cpumask_of_bp(bp); |
195 | int cpu; | |
ba1c813a | 196 | |
7ab71f32 ON |
197 | if (!enable) |
198 | weight = -weight; | |
199 | ||
45a73372 | 200 | /* Pinned counter cpu profiling */ |
50f16a8b | 201 | if (!bp->hw.target) { |
bde96030 | 202 | get_bp_info(bp->cpu, type)->cpu_pinned += weight; |
45a73372 FW |
203 | return; |
204 | } | |
205 | ||
ba1c813a | 206 | /* Pinned counter task profiling */ |
1c10adbb | 207 | for_each_cpu(cpu, cpumask) |
7ab71f32 | 208 | toggle_bp_task_slot(bp, cpu, type, weight); |
ba1c813a | 209 | |
ba1c813a | 210 | if (enable) |
45a73372 | 211 | list_add_tail(&bp->hw.bp_list, &bp_task_head); |
e1ebe862 ON |
212 | else |
213 | list_del(&bp->hw.bp_list); | |
ba1c813a FW |
214 | } |
215 | ||
f7136c51 P |
216 | /* |
217 | * Function to perform processor-specific cleanup during unregistration | |
218 | */ | |
219 | __weak void arch_unregister_hw_breakpoint(struct perf_event *bp) | |
220 | { | |
221 | /* | |
222 | * A weak stub function here for those archs that don't define | |
223 | * it inside arch/.../kernel/hw_breakpoint.c | |
224 | */ | |
225 | } | |
226 | ||
ba1c813a | 227 | /* |
fca0c116 | 228 | * Constraints to check before allowing this new breakpoint counter: |
ba1c813a FW |
229 | * |
230 | * == Non-pinned counter == (Considered as pinned for now) | |
231 | * | |
232 | * - If attached to a single cpu, check: | |
233 | * | |
bde96030 ON |
234 | * (per_cpu(info->flexible, cpu) || (per_cpu(info->cpu_pinned, cpu) |
235 | * + max(per_cpu(info->tsk_pinned, cpu)))) < HBP_NUM | |
ba1c813a FW |
236 | * |
237 | * -> If there are already non-pinned counters in this cpu, it means | |
238 | * there is already a free slot for them. | |
239 | * Otherwise, we check that the maximum number of per task | |
240 | * breakpoints (for this cpu) plus the number of per cpu breakpoint | |
241 | * (for this cpu) doesn't cover every registers. | |
242 | * | |
243 | * - If attached to every cpus, check: | |
244 | * | |
bde96030 ON |
245 | * (per_cpu(info->flexible, *) || (max(per_cpu(info->cpu_pinned, *)) |
246 | * + max(per_cpu(info->tsk_pinned, *)))) < HBP_NUM | |
ba1c813a FW |
247 | * |
248 | * -> This is roughly the same, except we check the number of per cpu | |
249 | * bp for every cpu and we keep the max one. Same for the per tasks | |
250 | * breakpoints. | |
251 | * | |
252 | * | |
253 | * == Pinned counter == | |
254 | * | |
255 | * - If attached to a single cpu, check: | |
256 | * | |
bde96030 ON |
257 | * ((per_cpu(info->flexible, cpu) > 1) + per_cpu(info->cpu_pinned, cpu) |
258 | * + max(per_cpu(info->tsk_pinned, cpu))) < HBP_NUM | |
ba1c813a | 259 | * |
bde96030 | 260 | * -> Same checks as before. But now the info->flexible, if any, must keep |
ba1c813a FW |
261 | * one register at least (or they will never be fed). |
262 | * | |
263 | * - If attached to every cpus, check: | |
264 | * | |
bde96030 ON |
265 | * ((per_cpu(info->flexible, *) > 1) + max(per_cpu(info->cpu_pinned, *)) |
266 | * + max(per_cpu(info->tsk_pinned, *))) < HBP_NUM | |
ba1c813a | 267 | */ |
1ad9ff7d | 268 | static int __reserve_bp_slot(struct perf_event *bp, u64 bp_type) |
ba1c813a FW |
269 | { |
270 | struct bp_busy_slots slots = {0}; | |
0102752e | 271 | enum bp_type_idx type; |
f93a2054 | 272 | int weight; |
ba1c813a | 273 | |
feef47d0 FW |
274 | /* We couldn't initialize breakpoint constraints on boot */ |
275 | if (!constraints_initialized) | |
276 | return -ENOMEM; | |
277 | ||
0102752e | 278 | /* Basic checks */ |
1ad9ff7d JO |
279 | if (bp_type == HW_BREAKPOINT_EMPTY || |
280 | bp_type == HW_BREAKPOINT_INVALID) | |
0102752e FW |
281 | return -EINVAL; |
282 | ||
1ad9ff7d | 283 | type = find_slot_idx(bp_type); |
f93a2054 FW |
284 | weight = hw_breakpoint_weight(bp); |
285 | ||
0102752e | 286 | fetch_bp_busy_slots(&slots, bp, type); |
45a73372 FW |
287 | /* |
288 | * Simulate the addition of this breakpoint to the constraints | |
289 | * and see the result. | |
290 | */ | |
f93a2054 | 291 | fetch_this_slot(&slots, weight); |
ba1c813a FW |
292 | |
293 | /* Flexible counters need to keep at least one slot */ | |
feef47d0 | 294 | if (slots.pinned + (!!slots.flexible) > nr_slots[type]) |
5352ae63 | 295 | return -ENOSPC; |
ba1c813a | 296 | |
f93a2054 | 297 | toggle_bp_slot(bp, true, type, weight); |
ba1c813a | 298 | |
5352ae63 JW |
299 | return 0; |
300 | } | |
301 | ||
302 | int reserve_bp_slot(struct perf_event *bp) | |
303 | { | |
304 | int ret; | |
305 | ||
306 | mutex_lock(&nr_bp_mutex); | |
307 | ||
1ad9ff7d | 308 | ret = __reserve_bp_slot(bp, bp->attr.bp_type); |
5352ae63 | 309 | |
ba1c813a FW |
310 | mutex_unlock(&nr_bp_mutex); |
311 | ||
312 | return ret; | |
313 | } | |
314 | ||
1ad9ff7d | 315 | static void __release_bp_slot(struct perf_event *bp, u64 bp_type) |
5352ae63 | 316 | { |
0102752e | 317 | enum bp_type_idx type; |
f93a2054 | 318 | int weight; |
0102752e | 319 | |
1ad9ff7d | 320 | type = find_slot_idx(bp_type); |
f93a2054 FW |
321 | weight = hw_breakpoint_weight(bp); |
322 | toggle_bp_slot(bp, false, type, weight); | |
5352ae63 JW |
323 | } |
324 | ||
24f1e32c | 325 | void release_bp_slot(struct perf_event *bp) |
62a038d3 | 326 | { |
ba1c813a FW |
327 | mutex_lock(&nr_bp_mutex); |
328 | ||
f7136c51 | 329 | arch_unregister_hw_breakpoint(bp); |
1ad9ff7d | 330 | __release_bp_slot(bp, bp->attr.bp_type); |
ba1c813a FW |
331 | |
332 | mutex_unlock(&nr_bp_mutex); | |
62a038d3 P |
333 | } |
334 | ||
cb8b7881 | 335 | static int __modify_bp_slot(struct perf_event *bp, u64 old_type, u64 new_type) |
ea6a9d53 JO |
336 | { |
337 | int err; | |
338 | ||
339 | __release_bp_slot(bp, old_type); | |
340 | ||
cb8b7881 | 341 | err = __reserve_bp_slot(bp, new_type); |
ea6a9d53 JO |
342 | if (err) { |
343 | /* | |
344 | * Reserve the old_type slot back in case | |
345 | * there's no space for the new type. | |
346 | * | |
347 | * This must succeed, because we just released | |
348 | * the old_type slot in the __release_bp_slot | |
349 | * call above. If not, something is broken. | |
350 | */ | |
351 | WARN_ON(__reserve_bp_slot(bp, old_type)); | |
352 | } | |
353 | ||
354 | return err; | |
355 | } | |
356 | ||
cb8b7881 | 357 | static int modify_bp_slot(struct perf_event *bp, u64 old_type, u64 new_type) |
ea6a9d53 JO |
358 | { |
359 | int ret; | |
360 | ||
361 | mutex_lock(&nr_bp_mutex); | |
cb8b7881 | 362 | ret = __modify_bp_slot(bp, old_type, new_type); |
ea6a9d53 JO |
363 | mutex_unlock(&nr_bp_mutex); |
364 | return ret; | |
365 | } | |
366 | ||
5352ae63 JW |
367 | /* |
368 | * Allow the kernel debugger to reserve breakpoint slots without | |
369 | * taking a lock using the dbg_* variant of for the reserve and | |
370 | * release breakpoint slots. | |
371 | */ | |
372 | int dbg_reserve_bp_slot(struct perf_event *bp) | |
373 | { | |
374 | if (mutex_is_locked(&nr_bp_mutex)) | |
375 | return -1; | |
376 | ||
1ad9ff7d | 377 | return __reserve_bp_slot(bp, bp->attr.bp_type); |
5352ae63 JW |
378 | } |
379 | ||
380 | int dbg_release_bp_slot(struct perf_event *bp) | |
381 | { | |
382 | if (mutex_is_locked(&nr_bp_mutex)) | |
383 | return -1; | |
384 | ||
1ad9ff7d | 385 | __release_bp_slot(bp, bp->attr.bp_type); |
5352ae63 JW |
386 | |
387 | return 0; | |
388 | } | |
ba1c813a | 389 | |
9a4903dd FW |
390 | static int hw_breakpoint_parse(struct perf_event *bp, |
391 | const struct perf_event_attr *attr, | |
392 | struct arch_hw_breakpoint *hw) | |
393 | { | |
394 | int err; | |
b2812d03 | 395 | |
9a4903dd FW |
396 | err = hw_breakpoint_arch_parse(bp, attr, hw); |
397 | if (err) | |
398 | return err; | |
b2812d03 | 399 | |
8e983ff9 | 400 | if (arch_check_bp_in_kernelspace(hw)) { |
9a4903dd | 401 | if (attr->exclude_kernel) |
b2812d03 FW |
402 | return -EINVAL; |
403 | /* | |
404 | * Don't let unprivileged users set a breakpoint in the trap | |
405 | * path to avoid trap recursion attacks. | |
406 | */ | |
407 | if (!capable(CAP_SYS_ADMIN)) | |
408 | return -EPERM; | |
409 | } | |
410 | ||
411 | return 0; | |
412 | } | |
413 | ||
b326e956 | 414 | int register_perf_hw_breakpoint(struct perf_event *bp) |
62a038d3 | 415 | { |
310aa0a2 | 416 | struct arch_hw_breakpoint hw = { }; |
9a4903dd | 417 | int err; |
62a038d3 | 418 | |
9a4903dd FW |
419 | err = reserve_bp_slot(bp); |
420 | if (err) | |
421 | return err; | |
62a038d3 | 422 | |
9a4903dd FW |
423 | err = hw_breakpoint_parse(bp, &bp->attr, &hw); |
424 | if (err) { | |
b23ff0e9 | 425 | release_bp_slot(bp); |
9a4903dd FW |
426 | return err; |
427 | } | |
b23ff0e9 | 428 | |
9a4903dd FW |
429 | bp->hw.info = hw; |
430 | ||
431 | return 0; | |
24f1e32c | 432 | } |
62a038d3 | 433 | |
62a038d3 P |
434 | /** |
435 | * register_user_hw_breakpoint - register a hardware breakpoint for user space | |
5fa10b28 | 436 | * @attr: breakpoint attributes |
24f1e32c | 437 | * @triggered: callback to trigger when we hit the breakpoint |
62a038d3 | 438 | * @tsk: pointer to 'task_struct' of the process to which the address belongs |
62a038d3 | 439 | */ |
24f1e32c | 440 | struct perf_event * |
5fa10b28 | 441 | register_user_hw_breakpoint(struct perf_event_attr *attr, |
b326e956 | 442 | perf_overflow_handler_t triggered, |
4dc0da86 | 443 | void *context, |
5fa10b28 | 444 | struct task_struct *tsk) |
62a038d3 | 445 | { |
4dc0da86 AK |
446 | return perf_event_create_kernel_counter(attr, -1, tsk, triggered, |
447 | context); | |
62a038d3 P |
448 | } |
449 | EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); | |
450 | ||
26c6ccdf FW |
451 | static void hw_breakpoint_copy_attr(struct perf_event_attr *to, |
452 | struct perf_event_attr *from) | |
453 | { | |
454 | to->bp_addr = from->bp_addr; | |
455 | to->bp_type = from->bp_type; | |
456 | to->bp_len = from->bp_len; | |
457 | to->disabled = from->disabled; | |
458 | } | |
459 | ||
32ff77e8 | 460 | int |
705feaf3 JO |
461 | modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *attr, |
462 | bool check) | |
18ff57b2 | 463 | { |
310aa0a2 | 464 | struct arch_hw_breakpoint hw = { }; |
26c6ccdf | 465 | int err; |
18ff57b2 | 466 | |
26c6ccdf FW |
467 | err = hw_breakpoint_parse(bp, attr, &hw); |
468 | if (err) | |
469 | return err; | |
18ff57b2 | 470 | |
26c6ccdf FW |
471 | if (check) { |
472 | struct perf_event_attr old_attr; | |
705feaf3 | 473 | |
26c6ccdf FW |
474 | old_attr = bp->attr; |
475 | hw_breakpoint_copy_attr(&old_attr, attr); | |
476 | if (memcmp(&old_attr, attr, sizeof(*attr))) | |
477 | return -EINVAL; | |
478 | } | |
18ff57b2 | 479 | |
26c6ccdf FW |
480 | if (bp->attr.bp_type != attr->bp_type) { |
481 | err = modify_bp_slot(bp, bp->attr.bp_type, attr->bp_type); | |
482 | if (err) | |
483 | return err; | |
18ff57b2 JO |
484 | } |
485 | ||
26c6ccdf | 486 | hw_breakpoint_copy_attr(&bp->attr, attr); |
9a4903dd | 487 | bp->hw.info = hw; |
9a4903dd | 488 | |
18ff57b2 JO |
489 | return 0; |
490 | } | |
491 | ||
62a038d3 P |
492 | /** |
493 | * modify_user_hw_breakpoint - modify a user-space hardware breakpoint | |
24f1e32c | 494 | * @bp: the breakpoint structure to modify |
5fa10b28 | 495 | * @attr: new breakpoint attributes |
62a038d3 | 496 | */ |
44234adc | 497 | int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) |
62a038d3 | 498 | { |
bd14406b JO |
499 | int err; |
500 | ||
500ad2d8 P |
501 | /* |
502 | * modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it | |
503 | * will not be possible to raise IPIs that invoke __perf_event_disable. | |
504 | * So call the function directly after making sure we are targeting the | |
505 | * current task. | |
506 | */ | |
507 | if (irqs_disabled() && bp->ctx && bp->ctx->task == current) | |
fae3fde6 | 508 | perf_event_disable_local(bp); |
500ad2d8 P |
509 | else |
510 | perf_event_disable(bp); | |
44234adc | 511 | |
bd14406b | 512 | err = modify_user_hw_breakpoint_check(bp, attr, false); |
44234adc | 513 | |
96955837 | 514 | if (!bp->attr.disabled) |
ea6a9d53 | 515 | perf_event_enable(bp); |
cb45302d | 516 | |
96955837 | 517 | return err; |
62a038d3 P |
518 | } |
519 | EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); | |
520 | ||
521 | /** | |
24f1e32c | 522 | * unregister_hw_breakpoint - unregister a user-space hardware breakpoint |
62a038d3 | 523 | * @bp: the breakpoint structure to unregister |
62a038d3 | 524 | */ |
24f1e32c | 525 | void unregister_hw_breakpoint(struct perf_event *bp) |
62a038d3 | 526 | { |
24f1e32c FW |
527 | if (!bp) |
528 | return; | |
529 | perf_event_release_kernel(bp); | |
530 | } | |
531 | EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); | |
532 | ||
62a038d3 | 533 | /** |
24f1e32c | 534 | * register_wide_hw_breakpoint - register a wide breakpoint in the kernel |
dd1853c3 | 535 | * @attr: breakpoint attributes |
24f1e32c | 536 | * @triggered: callback to trigger when we hit the breakpoint |
62a038d3 | 537 | * |
24f1e32c | 538 | * @return a set of per_cpu pointers to perf events |
62a038d3 | 539 | */ |
44ee6358 | 540 | struct perf_event * __percpu * |
dd1853c3 | 541 | register_wide_hw_breakpoint(struct perf_event_attr *attr, |
4dc0da86 AK |
542 | perf_overflow_handler_t triggered, |
543 | void *context) | |
62a038d3 | 544 | { |
e12cbc10 ON |
545 | struct perf_event * __percpu *cpu_events, *bp; |
546 | long err = 0; | |
24f1e32c FW |
547 | int cpu; |
548 | ||
549 | cpu_events = alloc_percpu(typeof(*cpu_events)); | |
550 | if (!cpu_events) | |
44ee6358 | 551 | return (void __percpu __force *)ERR_PTR(-ENOMEM); |
62a038d3 | 552 | |
88f7a890 LZ |
553 | get_online_cpus(); |
554 | for_each_online_cpu(cpu) { | |
4dc0da86 AK |
555 | bp = perf_event_create_kernel_counter(attr, cpu, NULL, |
556 | triggered, context); | |
605bfaee | 557 | if (IS_ERR(bp)) { |
24f1e32c | 558 | err = PTR_ERR(bp); |
e12cbc10 | 559 | break; |
24f1e32c | 560 | } |
24f1e32c | 561 | |
e12cbc10 | 562 | per_cpu(*cpu_events, cpu) = bp; |
24f1e32c | 563 | } |
88f7a890 LZ |
564 | put_online_cpus(); |
565 | ||
e12cbc10 ON |
566 | if (likely(!err)) |
567 | return cpu_events; | |
568 | ||
569 | unregister_wide_hw_breakpoint(cpu_events); | |
44ee6358 | 570 | return (void __percpu __force *)ERR_PTR(err); |
62a038d3 | 571 | } |
f60d24d2 | 572 | EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint); |
62a038d3 P |
573 | |
574 | /** | |
24f1e32c FW |
575 | * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel |
576 | * @cpu_events: the per cpu set of events to unregister | |
62a038d3 | 577 | */ |
44ee6358 | 578 | void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events) |
62a038d3 | 579 | { |
24f1e32c | 580 | int cpu; |
62a038d3 | 581 | |
e12cbc10 ON |
582 | for_each_possible_cpu(cpu) |
583 | unregister_hw_breakpoint(per_cpu(*cpu_events, cpu)); | |
584 | ||
24f1e32c | 585 | free_percpu(cpu_events); |
62a038d3 | 586 | } |
f60d24d2 | 587 | EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint); |
62a038d3 P |
588 | |
589 | static struct notifier_block hw_breakpoint_exceptions_nb = { | |
590 | .notifier_call = hw_breakpoint_exceptions_notify, | |
591 | /* we need to be notified first */ | |
592 | .priority = 0x7fffffff | |
593 | }; | |
594 | ||
b0a873eb PZ |
595 | static void bp_perf_event_destroy(struct perf_event *event) |
596 | { | |
597 | release_bp_slot(event); | |
598 | } | |
599 | ||
600 | static int hw_breakpoint_event_init(struct perf_event *bp) | |
601 | { | |
602 | int err; | |
603 | ||
604 | if (bp->attr.type != PERF_TYPE_BREAKPOINT) | |
605 | return -ENOENT; | |
606 | ||
2481c5fa SE |
607 | /* |
608 | * no branch sampling for breakpoint events | |
609 | */ | |
610 | if (has_branch_stack(bp)) | |
611 | return -EOPNOTSUPP; | |
612 | ||
b0a873eb PZ |
613 | err = register_perf_hw_breakpoint(bp); |
614 | if (err) | |
615 | return err; | |
616 | ||
617 | bp->destroy = bp_perf_event_destroy; | |
618 | ||
619 | return 0; | |
620 | } | |
621 | ||
a4eaf7f1 PZ |
622 | static int hw_breakpoint_add(struct perf_event *bp, int flags) |
623 | { | |
624 | if (!(flags & PERF_EF_START)) | |
625 | bp->hw.state = PERF_HES_STOPPED; | |
626 | ||
ab573844 JO |
627 | if (is_sampling_event(bp)) { |
628 | bp->hw.last_period = bp->hw.sample_period; | |
629 | perf_swevent_set_period(bp); | |
630 | } | |
631 | ||
a4eaf7f1 PZ |
632 | return arch_install_hw_breakpoint(bp); |
633 | } | |
634 | ||
635 | static void hw_breakpoint_del(struct perf_event *bp, int flags) | |
636 | { | |
637 | arch_uninstall_hw_breakpoint(bp); | |
638 | } | |
639 | ||
640 | static void hw_breakpoint_start(struct perf_event *bp, int flags) | |
641 | { | |
642 | bp->hw.state = 0; | |
643 | } | |
644 | ||
645 | static void hw_breakpoint_stop(struct perf_event *bp, int flags) | |
646 | { | |
647 | bp->hw.state = PERF_HES_STOPPED; | |
648 | } | |
649 | ||
b0a873eb | 650 | static struct pmu perf_breakpoint = { |
89a1e187 PZ |
651 | .task_ctx_nr = perf_sw_context, /* could eventually get its own */ |
652 | ||
b0a873eb | 653 | .event_init = hw_breakpoint_event_init, |
a4eaf7f1 PZ |
654 | .add = hw_breakpoint_add, |
655 | .del = hw_breakpoint_del, | |
656 | .start = hw_breakpoint_start, | |
657 | .stop = hw_breakpoint_stop, | |
b0a873eb PZ |
658 | .read = hw_breakpoint_pmu_read, |
659 | }; | |
660 | ||
3c502e7a | 661 | int __init init_hw_breakpoint(void) |
62a038d3 | 662 | { |
feef47d0 FW |
663 | int cpu, err_cpu; |
664 | int i; | |
665 | ||
666 | for (i = 0; i < TYPE_MAX; i++) | |
667 | nr_slots[i] = hw_breakpoint_slots(i); | |
668 | ||
669 | for_each_possible_cpu(cpu) { | |
670 | for (i = 0; i < TYPE_MAX; i++) { | |
bde96030 ON |
671 | struct bp_cpuinfo *info = get_bp_info(cpu, i); |
672 | ||
673 | info->tsk_pinned = kcalloc(nr_slots[i], sizeof(int), | |
674 | GFP_KERNEL); | |
675 | if (!info->tsk_pinned) | |
feef47d0 FW |
676 | goto err_alloc; |
677 | } | |
678 | } | |
679 | ||
680 | constraints_initialized = 1; | |
681 | ||
2e80a82a | 682 | perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT); |
b0a873eb | 683 | |
62a038d3 | 684 | return register_die_notifier(&hw_breakpoint_exceptions_nb); |
feef47d0 FW |
685 | |
686 | err_alloc: | |
687 | for_each_possible_cpu(err_cpu) { | |
feef47d0 | 688 | for (i = 0; i < TYPE_MAX; i++) |
bde96030 | 689 | kfree(get_bp_info(err_cpu, i)->tsk_pinned); |
30ce2f7e NK |
690 | if (err_cpu == cpu) |
691 | break; | |
feef47d0 FW |
692 | } |
693 | ||
694 | return -ENOMEM; | |
62a038d3 | 695 | } |
24f1e32c FW |
696 | |
697 |