blob: 086adf25a55e3aaecf3eb3172a7569b2c1a209e0 [file] [log] [blame]
K.Prasad62a038d2009-06-01 23:43:33 +05301/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * along with this program; if not, write to the Free Software
14 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
15 *
16 * Copyright (C) 2007 Alan Stern
17 * Copyright (C) IBM Corporation, 2009
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020018 * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020019 *
20 * Thanks to Ingo Molnar for his many suggestions.
K.Prasadba6909b2009-11-23 21:17:13 +053021 *
22 * Authors: Alan Stern <stern@rowland.harvard.edu>
23 * K.Prasad <prasad@linux.vnet.ibm.com>
24 * Frederic Weisbecker <fweisbec@gmail.com>
K.Prasad62a038d2009-06-01 23:43:33 +053025 */
26
27/*
28 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
29 * using the CPU's debug registers.
30 * This file contains the arch-independent routines.
31 */
32
33#include <linux/irqflags.h>
34#include <linux/kallsyms.h>
35#include <linux/notifier.h>
36#include <linux/kprobes.h>
37#include <linux/kdebug.h>
38#include <linux/kernel.h>
39#include <linux/module.h>
40#include <linux/percpu.h>
41#include <linux/sched.h>
42#include <linux/init.h>
Frederic Weisbeckerfeef47d2010-04-23 05:59:55 +020043#include <linux/slab.h>
Frederic Weisbecker45a73372010-06-23 23:00:37 +020044#include <linux/list.h>
Li Zefan88f7a8902009-12-30 14:22:22 +080045#include <linux/cpu.h>
K.Prasad62a038d2009-06-01 23:43:33 +053046#include <linux/smp.h>
47
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020048#include <linux/hw_breakpoint.h>
49
Frederic Weisbecker01027522010-04-11 18:55:56 +020050
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020051/*
52 * Constraints data
53 */
K.Prasad62a038d2009-06-01 23:43:33 +053054
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020055/* Number of pinned cpu breakpoints in a cpu */
Frederic Weisbecker01027522010-04-11 18:55:56 +020056static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020057
58/* Number of pinned task breakpoints in a cpu */
Frederic Weisbecker777d0412010-05-03 15:39:45 +020059static DEFINE_PER_CPU(unsigned int *, nr_task_bp_pinned[TYPE_MAX]);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020060
61/* Number of non-pinned cpu/task breakpoints in a cpu */
Frederic Weisbecker01027522010-04-11 18:55:56 +020062static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020063
Frederic Weisbeckerfeef47d2010-04-23 05:59:55 +020064static int nr_slots[TYPE_MAX];
65
Frederic Weisbecker45a73372010-06-23 23:00:37 +020066/* Keep track of the breakpoints attached to tasks */
67static LIST_HEAD(bp_task_head);
68
Frederic Weisbeckerfeef47d2010-04-23 05:59:55 +020069static int constraints_initialized;
70
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020071/* Gather the number of total pinned and un-pinned bp in a cpuset */
72struct bp_busy_slots {
73 unsigned int pinned;
74 unsigned int flexible;
75};
76
77/* Serialize accesses to the above constraints */
78static DEFINE_MUTEX(nr_bp_mutex);
79
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +020080__weak int hw_breakpoint_weight(struct perf_event *bp)
81{
82 return 1;
83}
84
Frederic Weisbecker01027522010-04-11 18:55:56 +020085static inline enum bp_type_idx find_slot_idx(struct perf_event *bp)
86{
87 if (bp->attr.bp_type & HW_BREAKPOINT_RW)
88 return TYPE_DATA;
89
90 return TYPE_INST;
91}
92
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020093/*
94 * Report the maximum number of pinned breakpoints a task
95 * have in this cpu
96 */
Frederic Weisbecker01027522010-04-11 18:55:56 +020097static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
K.Prasad62a038d2009-06-01 23:43:33 +053098{
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +020099 int i;
Frederic Weisbecker01027522010-04-11 18:55:56 +0200100 unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
K.Prasad62a038d2009-06-01 23:43:33 +0530101
Frederic Weisbeckerfeef47d2010-04-23 05:59:55 +0200102 for (i = nr_slots[type] - 1; i >= 0; i--) {
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200103 if (tsk_pinned[i] > 0)
104 return i + 1;
K.Prasad62a038d2009-06-01 23:43:33 +0530105 }
106
K.Prasad62a038d2009-06-01 23:43:33 +0530107 return 0;
108}
109
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200110/*
111 * Count the number of breakpoints of the same type and same task.
112 * The given event must be not on the list.
113 */
114static int task_bp_pinned(struct perf_event *bp, enum bp_type_idx type)
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200115{
Peter Zijlstrad580ff82010-10-14 17:43:23 +0200116 struct task_struct *tsk = bp->hw.bp_target;
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200117 struct perf_event *iter;
Frederic Weisbecker56053172009-12-07 06:46:48 +0100118 int count = 0;
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200119
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200120 list_for_each_entry(iter, &bp_task_head, hw.bp_list) {
Peter Zijlstrad580ff82010-10-14 17:43:23 +0200121 if (iter->hw.bp_target == tsk && find_slot_idx(iter) == type)
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200122 count += hw_breakpoint_weight(iter);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200123 }
124
Frederic Weisbecker56053172009-12-07 06:46:48 +0100125 return count;
126}
127
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 */
132static void
Frederic Weisbecker01027522010-04-11 18:55:56 +0200133fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
134 enum bp_type_idx type)
Frederic Weisbecker56053172009-12-07 06:46:48 +0100135{
136 int cpu = bp->cpu;
Peter Zijlstrad580ff82010-10-14 17:43:23 +0200137 struct task_struct *tsk = bp->hw.bp_target;
Frederic Weisbecker56053172009-12-07 06:46:48 +0100138
139 if (cpu >= 0) {
Frederic Weisbecker01027522010-04-11 18:55:56 +0200140 slots->pinned = per_cpu(nr_cpu_bp_pinned[type], cpu);
Frederic Weisbecker56053172009-12-07 06:46:48 +0100141 if (!tsk)
Frederic Weisbecker01027522010-04-11 18:55:56 +0200142 slots->pinned += max_task_bp_pinned(cpu, type);
Frederic Weisbecker56053172009-12-07 06:46:48 +0100143 else
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200144 slots->pinned += task_bp_pinned(bp, type);
Frederic Weisbecker01027522010-04-11 18:55:56 +0200145 slots->flexible = per_cpu(nr_bp_flexible[type], cpu);
Frederic Weisbecker56053172009-12-07 06:46:48 +0100146
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200147 return;
Frederic Weisbecker56053172009-12-07 06:46:48 +0100148 }
149
150 for_each_online_cpu(cpu) {
151 unsigned int nr;
152
Frederic Weisbecker01027522010-04-11 18:55:56 +0200153 nr = per_cpu(nr_cpu_bp_pinned[type], cpu);
Frederic Weisbecker56053172009-12-07 06:46:48 +0100154 if (!tsk)
Frederic Weisbecker01027522010-04-11 18:55:56 +0200155 nr += max_task_bp_pinned(cpu, type);
Frederic Weisbecker56053172009-12-07 06:46:48 +0100156 else
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200157 nr += task_bp_pinned(bp, type);
Frederic Weisbecker56053172009-12-07 06:46:48 +0100158
159 if (nr > slots->pinned)
160 slots->pinned = nr;
161
Frederic Weisbecker01027522010-04-11 18:55:56 +0200162 nr = per_cpu(nr_bp_flexible[type], cpu);
Frederic Weisbecker56053172009-12-07 06:46:48 +0100163
164 if (nr > slots->flexible)
165 slots->flexible = nr;
166 }
167}
168
169/*
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200170 * For now, continue to consider flexible as pinned, until we can
171 * ensure no flexible event can ever be scheduled before a pinned event
172 * in a same cpu.
173 */
174static void
175fetch_this_slot(struct bp_busy_slots *slots, int weight)
176{
177 slots->pinned += weight;
178}
179
180/*
Frederic Weisbecker56053172009-12-07 06:46:48 +0100181 * Add a pinned breakpoint for the given task in our constraint table
182 */
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200183static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable,
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200184 enum bp_type_idx type, int weight)
Frederic Weisbecker56053172009-12-07 06:46:48 +0100185{
186 unsigned int *tsk_pinned;
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200187 int old_count = 0;
188 int old_idx = 0;
189 int idx = 0;
Frederic Weisbecker56053172009-12-07 06:46:48 +0100190
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200191 old_count = task_bp_pinned(bp, type);
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200192 old_idx = old_count - 1;
193 idx = old_idx + weight;
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200194
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200195 /* tsk_pinned[n] is the number of tasks having n breakpoints */
Frederic Weisbecker01027522010-04-11 18:55:56 +0200196 tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200197 if (enable) {
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200198 tsk_pinned[idx]++;
199 if (old_count > 0)
200 tsk_pinned[old_idx]--;
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200201 } else {
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200202 tsk_pinned[idx]--;
203 if (old_count > 0)
204 tsk_pinned[old_idx]++;
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200205 }
206}
207
208/*
209 * Add/remove the given breakpoint in our constraint table
210 */
Frederic Weisbecker01027522010-04-11 18:55:56 +0200211static void
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200212toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
213 int weight)
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200214{
215 int cpu = bp->cpu;
Peter Zijlstrad580ff82010-10-14 17:43:23 +0200216 struct task_struct *tsk = bp->hw.bp_target;
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200217
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200218 /* Pinned counter cpu profiling */
219 if (!tsk) {
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200220
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200221 if (enable)
222 per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight;
223 else
224 per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight;
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200225 return;
226 }
227
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200228 /* Pinned counter task profiling */
229
230 if (!enable)
231 list_del(&bp->hw.bp_list);
232
233 if (cpu >= 0) {
234 toggle_bp_task_slot(bp, cpu, enable, type, weight);
235 } else {
236 for_each_online_cpu(cpu)
237 toggle_bp_task_slot(bp, cpu, enable, type, weight);
238 }
239
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200240 if (enable)
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200241 list_add_tail(&bp->hw.bp_list, &bp_task_head);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200242}
243
244/*
K.Prasadf7136c52010-06-15 11:34:34 +0530245 * Function to perform processor-specific cleanup during unregistration
246 */
247__weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
248{
249 /*
250 * A weak stub function here for those archs that don't define
251 * it inside arch/.../kernel/hw_breakpoint.c
252 */
253}
254
255/*
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200256 * Contraints to check before allowing this new breakpoint counter:
257 *
258 * == Non-pinned counter == (Considered as pinned for now)
259 *
260 * - If attached to a single cpu, check:
261 *
262 * (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu)
Stephen Rothwell6ab88862009-12-08 18:25:15 +1100263 * + max(per_cpu(nr_task_bp_pinned, cpu)))) < HBP_NUM
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200264 *
265 * -> If there are already non-pinned counters in this cpu, it means
266 * there is already a free slot for them.
267 * Otherwise, we check that the maximum number of per task
268 * breakpoints (for this cpu) plus the number of per cpu breakpoint
269 * (for this cpu) doesn't cover every registers.
270 *
271 * - If attached to every cpus, check:
272 *
273 * (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *))
Stephen Rothwell6ab88862009-12-08 18:25:15 +1100274 * + max(per_cpu(nr_task_bp_pinned, *)))) < HBP_NUM
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200275 *
276 * -> This is roughly the same, except we check the number of per cpu
277 * bp for every cpu and we keep the max one. Same for the per tasks
278 * breakpoints.
279 *
280 *
281 * == Pinned counter ==
282 *
283 * - If attached to a single cpu, check:
284 *
285 * ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu)
Stephen Rothwell6ab88862009-12-08 18:25:15 +1100286 * + max(per_cpu(nr_task_bp_pinned, cpu))) < HBP_NUM
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200287 *
288 * -> Same checks as before. But now the nr_bp_flexible, if any, must keep
289 * one register at least (or they will never be fed).
290 *
291 * - If attached to every cpus, check:
292 *
293 * ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *))
Stephen Rothwell6ab88862009-12-08 18:25:15 +1100294 * + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200295 */
Jason Wessel5352ae632010-01-28 17:04:43 -0600296static int __reserve_bp_slot(struct perf_event *bp)
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200297{
298 struct bp_busy_slots slots = {0};
Frederic Weisbecker01027522010-04-11 18:55:56 +0200299 enum bp_type_idx type;
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200300 int weight;
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200301
Frederic Weisbeckerfeef47d2010-04-23 05:59:55 +0200302 /* We couldn't initialize breakpoint constraints on boot */
303 if (!constraints_initialized)
304 return -ENOMEM;
305
Frederic Weisbecker01027522010-04-11 18:55:56 +0200306 /* Basic checks */
307 if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY ||
308 bp->attr.bp_type == HW_BREAKPOINT_INVALID)
309 return -EINVAL;
310
311 type = find_slot_idx(bp);
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200312 weight = hw_breakpoint_weight(bp);
313
Frederic Weisbecker01027522010-04-11 18:55:56 +0200314 fetch_bp_busy_slots(&slots, bp, type);
Frederic Weisbecker45a73372010-06-23 23:00:37 +0200315 /*
316 * Simulate the addition of this breakpoint to the constraints
317 * and see the result.
318 */
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200319 fetch_this_slot(&slots, weight);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200320
321 /* Flexible counters need to keep at least one slot */
Frederic Weisbeckerfeef47d2010-04-23 05:59:55 +0200322 if (slots.pinned + (!!slots.flexible) > nr_slots[type])
Jason Wessel5352ae632010-01-28 17:04:43 -0600323 return -ENOSPC;
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200324
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200325 toggle_bp_slot(bp, true, type, weight);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200326
Jason Wessel5352ae632010-01-28 17:04:43 -0600327 return 0;
328}
329
330int reserve_bp_slot(struct perf_event *bp)
331{
332 int ret;
333
334 mutex_lock(&nr_bp_mutex);
335
336 ret = __reserve_bp_slot(bp);
337
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200338 mutex_unlock(&nr_bp_mutex);
339
340 return ret;
341}
342
Jason Wessel5352ae632010-01-28 17:04:43 -0600343static void __release_bp_slot(struct perf_event *bp)
344{
Frederic Weisbecker01027522010-04-11 18:55:56 +0200345 enum bp_type_idx type;
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200346 int weight;
Frederic Weisbecker01027522010-04-11 18:55:56 +0200347
348 type = find_slot_idx(bp);
Frederic Weisbeckerf93a2052010-04-13 00:32:30 +0200349 weight = hw_breakpoint_weight(bp);
350 toggle_bp_slot(bp, false, type, weight);
Jason Wessel5352ae632010-01-28 17:04:43 -0600351}
352
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200353void release_bp_slot(struct perf_event *bp)
K.Prasad62a038d2009-06-01 23:43:33 +0530354{
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200355 mutex_lock(&nr_bp_mutex);
356
K.Prasadf7136c52010-06-15 11:34:34 +0530357 arch_unregister_hw_breakpoint(bp);
Jason Wessel5352ae632010-01-28 17:04:43 -0600358 __release_bp_slot(bp);
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200359
360 mutex_unlock(&nr_bp_mutex);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200361}
K.Prasad62a038d2009-06-01 23:43:33 +0530362
Jason Wessel5352ae632010-01-28 17:04:43 -0600363/*
364 * Allow the kernel debugger to reserve breakpoint slots without
365 * taking a lock using the dbg_* variant of for the reserve and
366 * release breakpoint slots.
367 */
368int dbg_reserve_bp_slot(struct perf_event *bp)
369{
370 if (mutex_is_locked(&nr_bp_mutex))
371 return -1;
372
373 return __reserve_bp_slot(bp);
374}
375
376int dbg_release_bp_slot(struct perf_event *bp)
377{
378 if (mutex_is_locked(&nr_bp_mutex))
379 return -1;
380
381 __release_bp_slot(bp);
382
383 return 0;
384}
Frederic Weisbeckerba1c8132009-09-10 09:26:21 +0200385
Frederic Weisbeckerb2812d02010-04-18 18:11:53 +0200386static int validate_hw_breakpoint(struct perf_event *bp)
387{
388 int ret;
389
390 ret = arch_validate_hwbkpt_settings(bp);
391 if (ret)
392 return ret;
393
394 if (arch_check_bp_in_kernelspace(bp)) {
395 if (bp->attr.exclude_kernel)
396 return -EINVAL;
397 /*
398 * Don't let unprivileged users set a breakpoint in the trap
399 * path to avoid trap recursion attacks.
400 */
401 if (!capable(CAP_SYS_ADMIN))
402 return -EPERM;
403 }
404
405 return 0;
406}
407
Frederic Weisbeckerb326e952009-12-05 09:44:31 +0100408int register_perf_hw_breakpoint(struct perf_event *bp)
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200409{
410 int ret;
K.Prasad62a038d2009-06-01 23:43:33 +0530411
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200412 ret = reserve_bp_slot(bp);
413 if (ret)
414 return ret;
K.Prasad62a038d2009-06-01 23:43:33 +0530415
Frederic Weisbeckerb2812d02010-04-18 18:11:53 +0200416 ret = validate_hw_breakpoint(bp);
K.Prasad62a038d2009-06-01 23:43:33 +0530417
Mahesh Salgaonkarb23ff0e2010-01-21 18:25:16 +0530418 /* if arch_validate_hwbkpt_settings() fails then release bp slot */
419 if (ret)
420 release_bp_slot(bp);
421
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200422 return ret;
423}
K.Prasad62a038d2009-06-01 23:43:33 +0530424
K.Prasad62a038d2009-06-01 23:43:33 +0530425/**
426 * register_user_hw_breakpoint - register a hardware breakpoint for user space
Frederic Weisbecker5fa10b22009-11-27 04:55:53 +0100427 * @attr: breakpoint attributes
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200428 * @triggered: callback to trigger when we hit the breakpoint
K.Prasad62a038d2009-06-01 23:43:33 +0530429 * @tsk: pointer to 'task_struct' of the process to which the address belongs
K.Prasad62a038d2009-06-01 23:43:33 +0530430 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200431struct perf_event *
Frederic Weisbecker5fa10b22009-11-27 04:55:53 +0100432register_user_hw_breakpoint(struct perf_event_attr *attr,
Frederic Weisbeckerb326e952009-12-05 09:44:31 +0100433 perf_overflow_handler_t triggered,
Frederic Weisbecker5fa10b22009-11-27 04:55:53 +0100434 struct task_struct *tsk)
K.Prasad62a038d2009-06-01 23:43:33 +0530435{
Matt Helsley38a81da2010-09-13 13:01:20 -0700436 return perf_event_create_kernel_counter(attr, -1, tsk, triggered);
K.Prasad62a038d2009-06-01 23:43:33 +0530437}
438EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
439
440/**
441 * modify_user_hw_breakpoint - modify a user-space hardware breakpoint
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200442 * @bp: the breakpoint structure to modify
Frederic Weisbecker5fa10b22009-11-27 04:55:53 +0100443 * @attr: new breakpoint attributes
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200444 * @triggered: callback to trigger when we hit the breakpoint
K.Prasad62a038d2009-06-01 23:43:33 +0530445 * @tsk: pointer to 'task_struct' of the process to which the address belongs
K.Prasad62a038d2009-06-01 23:43:33 +0530446 */
Frederic Weisbecker44234ad2009-12-09 09:25:48 +0100447int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
K.Prasad62a038d2009-06-01 23:43:33 +0530448{
Frederic Weisbecker44234ad2009-12-09 09:25:48 +0100449 u64 old_addr = bp->attr.bp_addr;
Mahesh Salgaonkarcd757642010-01-30 10:25:18 +0530450 u64 old_len = bp->attr.bp_len;
Frederic Weisbecker44234ad2009-12-09 09:25:48 +0100451 int old_type = bp->attr.bp_type;
Frederic Weisbecker44234ad2009-12-09 09:25:48 +0100452 int err = 0;
K.Prasad62a038d2009-06-01 23:43:33 +0530453
Frederic Weisbecker44234ad2009-12-09 09:25:48 +0100454 perf_event_disable(bp);
455
456 bp->attr.bp_addr = attr->bp_addr;
457 bp->attr.bp_type = attr->bp_type;
458 bp->attr.bp_len = attr->bp_len;
459
460 if (attr->disabled)
461 goto end;
462
Frederic Weisbeckerb2812d02010-04-18 18:11:53 +0200463 err = validate_hw_breakpoint(bp);
Frederic Weisbecker44234ad2009-12-09 09:25:48 +0100464 if (!err)
465 perf_event_enable(bp);
466
467 if (err) {
468 bp->attr.bp_addr = old_addr;
469 bp->attr.bp_type = old_type;
470 bp->attr.bp_len = old_len;
471 if (!bp->attr.disabled)
472 perf_event_enable(bp);
473
474 return err;
475 }
476
477end:
478 bp->attr.disabled = attr->disabled;
479
480 return 0;
K.Prasad62a038d2009-06-01 23:43:33 +0530481}
482EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
483
484/**
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200485 * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
K.Prasad62a038d2009-06-01 23:43:33 +0530486 * @bp: the breakpoint structure to unregister
K.Prasad62a038d2009-06-01 23:43:33 +0530487 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200488void unregister_hw_breakpoint(struct perf_event *bp)
K.Prasad62a038d2009-06-01 23:43:33 +0530489{
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200490 if (!bp)
K.Prasad62a038d2009-06-01 23:43:33 +0530491 return;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200492 perf_event_release_kernel(bp);
493}
494EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
495
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200496/**
497 * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
Frederic Weisbeckerdd1853c2009-11-27 04:55:54 +0100498 * @attr: breakpoint attributes
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200499 * @triggered: callback to trigger when we hit the breakpoint
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200500 *
501 * @return a set of per_cpu pointers to perf events
502 */
Tejun Heo44ee6352010-02-17 10:50:50 +0900503struct perf_event * __percpu *
Frederic Weisbeckerdd1853c2009-11-27 04:55:54 +0100504register_wide_hw_breakpoint(struct perf_event_attr *attr,
Frederic Weisbeckerb326e952009-12-05 09:44:31 +0100505 perf_overflow_handler_t triggered)
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200506{
Tejun Heo44ee6352010-02-17 10:50:50 +0900507 struct perf_event * __percpu *cpu_events, **pevent, *bp;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200508 long err;
509 int cpu;
510
511 cpu_events = alloc_percpu(typeof(*cpu_events));
512 if (!cpu_events)
Tejun Heo44ee6352010-02-17 10:50:50 +0900513 return (void __percpu __force *)ERR_PTR(-ENOMEM);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200514
Li Zefan88f7a8902009-12-30 14:22:22 +0800515 get_online_cpus();
516 for_each_online_cpu(cpu) {
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200517 pevent = per_cpu_ptr(cpu_events, cpu);
Matt Helsley38a81da2010-09-13 13:01:20 -0700518 bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200519
520 *pevent = bp;
521
Frederic Weisbecker605bfae2009-11-26 05:35:42 +0100522 if (IS_ERR(bp)) {
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200523 err = PTR_ERR(bp);
524 goto fail;
525 }
K.Prasad62a038d2009-06-01 23:43:33 +0530526 }
Li Zefan88f7a8902009-12-30 14:22:22 +0800527 put_online_cpus();
K.Prasad62a038d2009-06-01 23:43:33 +0530528
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200529 return cpu_events;
K.Prasad62a038d2009-06-01 23:43:33 +0530530
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200531fail:
Li Zefan88f7a8902009-12-30 14:22:22 +0800532 for_each_online_cpu(cpu) {
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200533 pevent = per_cpu_ptr(cpu_events, cpu);
Frederic Weisbecker605bfae2009-11-26 05:35:42 +0100534 if (IS_ERR(*pevent))
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200535 break;
536 unregister_hw_breakpoint(*pevent);
537 }
Li Zefan88f7a8902009-12-30 14:22:22 +0800538 put_online_cpus();
539
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200540 free_percpu(cpu_events);
Tejun Heo44ee6352010-02-17 10:50:50 +0900541 return (void __percpu __force *)ERR_PTR(err);
K.Prasad62a038d2009-06-01 23:43:33 +0530542}
Frederic Weisbeckerf60d24d2009-11-10 10:17:07 +0100543EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200544
545/**
546 * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
547 * @cpu_events: the per cpu set of events to unregister
548 */
Tejun Heo44ee6352010-02-17 10:50:50 +0900549void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200550{
551 int cpu;
552 struct perf_event **pevent;
553
554 for_each_possible_cpu(cpu) {
555 pevent = per_cpu_ptr(cpu_events, cpu);
556 unregister_hw_breakpoint(*pevent);
557 }
558 free_percpu(cpu_events);
559}
Frederic Weisbeckerf60d24d2009-11-10 10:17:07 +0100560EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
K.Prasad62a038d2009-06-01 23:43:33 +0530561
562static struct notifier_block hw_breakpoint_exceptions_nb = {
563 .notifier_call = hw_breakpoint_exceptions_notify,
564 /* we need to be notified first */
565 .priority = 0x7fffffff
566};
567
Peter Zijlstrab0a873e2010-06-11 13:35:08 +0200568static void bp_perf_event_destroy(struct perf_event *event)
569{
570 release_bp_slot(event);
571}
572
573static int hw_breakpoint_event_init(struct perf_event *bp)
574{
575 int err;
576
577 if (bp->attr.type != PERF_TYPE_BREAKPOINT)
578 return -ENOENT;
579
580 err = register_perf_hw_breakpoint(bp);
581 if (err)
582 return err;
583
584 bp->destroy = bp_perf_event_destroy;
585
586 return 0;
587}
588
Peter Zijlstraa4eaf7f2010-06-16 14:37:10 +0200589static int hw_breakpoint_add(struct perf_event *bp, int flags)
590{
591 if (!(flags & PERF_EF_START))
592 bp->hw.state = PERF_HES_STOPPED;
593
594 return arch_install_hw_breakpoint(bp);
595}
596
597static void hw_breakpoint_del(struct perf_event *bp, int flags)
598{
599 arch_uninstall_hw_breakpoint(bp);
600}
601
602static void hw_breakpoint_start(struct perf_event *bp, int flags)
603{
604 bp->hw.state = 0;
605}
606
607static void hw_breakpoint_stop(struct perf_event *bp, int flags)
608{
609 bp->hw.state = PERF_HES_STOPPED;
610}
611
Peter Zijlstrab0a873e2010-06-11 13:35:08 +0200612static struct pmu perf_breakpoint = {
Peter Zijlstra89a1e182010-09-07 17:34:50 +0200613 .task_ctx_nr = perf_sw_context, /* could eventually get its own */
614
Peter Zijlstrab0a873e2010-06-11 13:35:08 +0200615 .event_init = hw_breakpoint_event_init,
Peter Zijlstraa4eaf7f2010-06-16 14:37:10 +0200616 .add = hw_breakpoint_add,
617 .del = hw_breakpoint_del,
618 .start = hw_breakpoint_start,
619 .stop = hw_breakpoint_stop,
Peter Zijlstrab0a873e2010-06-11 13:35:08 +0200620 .read = hw_breakpoint_pmu_read,
621};
622
Jason Wessel3c502e72010-11-04 17:33:01 -0500623int __init init_hw_breakpoint(void)
K.Prasad62a038d2009-06-01 23:43:33 +0530624{
Frederic Weisbeckerfeef47d2010-04-23 05:59:55 +0200625 unsigned int **task_bp_pinned;
626 int cpu, err_cpu;
627 int i;
628
629 for (i = 0; i < TYPE_MAX; i++)
630 nr_slots[i] = hw_breakpoint_slots(i);
631
632 for_each_possible_cpu(cpu) {
633 for (i = 0; i < TYPE_MAX; i++) {
634 task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu);
635 *task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i],
636 GFP_KERNEL);
637 if (!*task_bp_pinned)
638 goto err_alloc;
639 }
640 }
641
642 constraints_initialized = 1;
643
Peter Zijlstra2e80a822010-11-17 23:17:36 +0100644 perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT);
Peter Zijlstrab0a873e2010-06-11 13:35:08 +0200645
K.Prasad62a038d2009-06-01 23:43:33 +0530646 return register_die_notifier(&hw_breakpoint_exceptions_nb);
Frederic Weisbeckerfeef47d2010-04-23 05:59:55 +0200647
648 err_alloc:
649 for_each_possible_cpu(err_cpu) {
650 if (err_cpu == cpu)
651 break;
652 for (i = 0; i < TYPE_MAX; i++)
653 kfree(per_cpu(nr_task_bp_pinned[i], cpu));
654 }
655
656 return -ENOMEM;
K.Prasad62a038d2009-06-01 23:43:33 +0530657}
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200658
659