blob: 05d5fec64a9475855e224012dbb54a9d82b1ee4c [file] [log] [blame]
K.Prasad0067f122009-06-01 23:43:57 +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) 2009 IBM Corporation
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020018 * Copyright (C) 2009 Frederic Weisbecker <fweisbec@gmail.com>
K.Prasadba6909b2009-11-23 21:17:13 +053019 *
20 * Authors: Alan Stern <stern@rowland.harvard.edu>
21 * K.Prasad <prasad@linux.vnet.ibm.com>
22 * Frederic Weisbecker <fweisbec@gmail.com>
K.Prasad0067f122009-06-01 23:43:57 +053023 */
24
25/*
26 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
27 * using the CPU's debug registers.
28 */
29
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020030#include <linux/perf_event.h>
31#include <linux/hw_breakpoint.h>
K.Prasad0067f122009-06-01 23:43:57 +053032#include <linux/irqflags.h>
33#include <linux/notifier.h>
34#include <linux/kallsyms.h>
35#include <linux/kprobes.h>
36#include <linux/percpu.h>
37#include <linux/kdebug.h>
38#include <linux/kernel.h>
39#include <linux/module.h>
40#include <linux/sched.h>
41#include <linux/init.h>
42#include <linux/smp.h>
43
44#include <asm/hw_breakpoint.h>
45#include <asm/processor.h>
46#include <asm/debugreg.h>
47
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020048/* Per cpu debug control register value */
Tejun Heo28b4e0d2009-11-25 22:24:44 +090049DEFINE_PER_CPU(unsigned long, cpu_dr7);
50EXPORT_PER_CPU_SYMBOL(cpu_dr7);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020051
52/* Per cpu debug address registers values */
53static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]);
K.Prasad0067f122009-06-01 23:43:57 +053054
55/*
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020056 * Stores the breakpoints currently in use on each breakpoint address
57 * register for each cpus
K.Prasad0067f122009-06-01 23:43:57 +053058 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020059static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);
K.Prasad0067f122009-06-01 23:43:57 +053060
61
Frederic Weisbecker2c31b792009-11-26 06:04:38 +010062static inline unsigned long
63__encode_dr7(int drnum, unsigned int len, unsigned int type)
64{
65 unsigned long bp_info;
66
67 bp_info = (len | type) & 0xf;
68 bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE);
69 bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE));
70
71 return bp_info;
72}
73
K.Prasad0067f122009-06-01 23:43:57 +053074/*
75 * Encode the length, type, Exact, and Enable bits for a particular breakpoint
76 * as stored in debug register 7.
77 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020078unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type)
K.Prasad0067f122009-06-01 23:43:57 +053079{
Frederic Weisbecker2c31b792009-11-26 06:04:38 +010080 return __encode_dr7(drnum, len, type) | DR_GLOBAL_SLOWDOWN;
K.Prasad0067f122009-06-01 23:43:57 +053081}
82
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020083/*
84 * Decode the length and type bits for a particular breakpoint as
85 * stored in debug register 7. Return the "enabled" status.
86 */
87int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type)
K.Prasad0067f122009-06-01 23:43:57 +053088{
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020089 int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE);
K.Prasad0067f122009-06-01 23:43:57 +053090
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020091 *len = (bp_info & 0xc) | 0x40;
92 *type = (bp_info & 0x3) | 0x80;
K.Prasad0067f122009-06-01 23:43:57 +053093
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +020094 return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3;
95}
96
97/*
98 * Install a perf counter breakpoint.
99 *
100 * We seek a free debug address register and use it for this
101 * breakpoint. Eventually we enable it in the debug control register.
102 *
103 * Atomic: we hold the counter->ctx->lock and we only handle variables
104 * and registers local to this cpu.
105 */
106int arch_install_hw_breakpoint(struct perf_event *bp)
107{
108 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
109 unsigned long *dr7;
110 int i;
111
112 for (i = 0; i < HBP_NUM; i++) {
113 struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
114
115 if (!*slot) {
116 *slot = bp;
117 break;
K.Prasad0067f122009-06-01 23:43:57 +0530118 }
119 }
120
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200121 if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
122 return -EBUSY;
123
124 set_debugreg(info->address, i);
125 __get_cpu_var(cpu_debugreg[i]) = info->address;
126
Tejun Heo28b4e0d2009-11-25 22:24:44 +0900127 dr7 = &__get_cpu_var(cpu_dr7);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200128 *dr7 |= encode_dr7(i, info->len, info->type);
129
130 set_debugreg(*dr7, 7);
131
132 return 0;
K.Prasad0067f122009-06-01 23:43:57 +0530133}
134
135/*
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200136 * Uninstall the breakpoint contained in the given counter.
137 *
138 * First we search the debug address register it uses and then we disable
139 * it.
140 *
141 * Atomic: we hold the counter->ctx->lock and we only handle variables
142 * and registers local to this cpu.
K.Prasad0067f122009-06-01 23:43:57 +0530143 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200144void arch_uninstall_hw_breakpoint(struct perf_event *bp)
K.Prasad0067f122009-06-01 23:43:57 +0530145{
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200146 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
147 unsigned long *dr7;
148 int i;
K.Prasad0067f122009-06-01 23:43:57 +0530149
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200150 for (i = 0; i < HBP_NUM; i++) {
151 struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
152
153 if (*slot == bp) {
154 *slot = NULL;
155 break;
156 }
K.Prasad0067f122009-06-01 23:43:57 +0530157 }
158
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200159 if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
160 return;
K.Prasad0067f122009-06-01 23:43:57 +0530161
Tejun Heo28b4e0d2009-11-25 22:24:44 +0900162 dr7 = &__get_cpu_var(cpu_dr7);
Frederic Weisbecker2c31b792009-11-26 06:04:38 +0100163 *dr7 &= ~__encode_dr7(i, info->len, info->type);
K.Prasad0067f122009-06-01 23:43:57 +0530164
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200165 set_debugreg(*dr7, 7);
K.Prasad0067f122009-06-01 23:43:57 +0530166}
167
168static int get_hbp_len(u8 hbp_len)
169{
170 unsigned int len_in_bytes = 0;
171
172 switch (hbp_len) {
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200173 case X86_BREAKPOINT_LEN_1:
K.Prasad0067f122009-06-01 23:43:57 +0530174 len_in_bytes = 1;
175 break;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200176 case X86_BREAKPOINT_LEN_2:
K.Prasad0067f122009-06-01 23:43:57 +0530177 len_in_bytes = 2;
178 break;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200179 case X86_BREAKPOINT_LEN_4:
K.Prasad0067f122009-06-01 23:43:57 +0530180 len_in_bytes = 4;
181 break;
182#ifdef CONFIG_X86_64
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200183 case X86_BREAKPOINT_LEN_8:
K.Prasad0067f122009-06-01 23:43:57 +0530184 len_in_bytes = 8;
185 break;
186#endif
187 }
188 return len_in_bytes;
189}
190
191/*
192 * Check for virtual address in user space.
193 */
194int arch_check_va_in_userspace(unsigned long va, u8 hbp_len)
195{
196 unsigned int len;
197
198 len = get_hbp_len(hbp_len);
199
200 return (va <= TASK_SIZE - len);
201}
202
203/*
204 * Check for virtual address in kernel space.
205 */
Jaswinder Singh Rajput45558352009-06-17 14:44:19 +0530206static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
K.Prasad0067f122009-06-01 23:43:57 +0530207{
208 unsigned int len;
209
210 len = get_hbp_len(hbp_len);
211
212 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
213}
214
215/*
216 * Store a breakpoint's encoded address, length, and type.
217 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200218static int arch_store_info(struct perf_event *bp)
K.Prasad0067f122009-06-01 23:43:57 +0530219{
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200220 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
K.Prasad0067f122009-06-01 23:43:57 +0530221 /*
222 * For kernel-addresses, either the address or symbol name can be
223 * specified.
224 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200225 if (info->name)
226 info->address = (unsigned long)
227 kallsyms_lookup_name(info->name);
228 if (info->address)
K.Prasad0067f122009-06-01 23:43:57 +0530229 return 0;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200230
K.Prasad0067f122009-06-01 23:43:57 +0530231 return -EINVAL;
232}
233
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200234int arch_bp_generic_fields(int x86_len, int x86_type,
235 int *gen_len, int *gen_type)
K.Prasad0067f122009-06-01 23:43:57 +0530236{
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200237 /* Len */
238 switch (x86_len) {
239 case X86_BREAKPOINT_LEN_1:
240 *gen_len = HW_BREAKPOINT_LEN_1;
K.Prasad0067f122009-06-01 23:43:57 +0530241 break;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200242 case X86_BREAKPOINT_LEN_2:
243 *gen_len = HW_BREAKPOINT_LEN_2;
K.Prasad0067f122009-06-01 23:43:57 +0530244 break;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200245 case X86_BREAKPOINT_LEN_4:
246 *gen_len = HW_BREAKPOINT_LEN_4;
K.Prasad0067f122009-06-01 23:43:57 +0530247 break;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200248#ifdef CONFIG_X86_64
249 case X86_BREAKPOINT_LEN_8:
250 *gen_len = HW_BREAKPOINT_LEN_8;
251 break;
252#endif
K.Prasad0067f122009-06-01 23:43:57 +0530253 default:
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200254 return -EINVAL;
K.Prasad0067f122009-06-01 23:43:57 +0530255 }
256
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200257 /* Type */
258 switch (x86_type) {
259 case X86_BREAKPOINT_EXECUTE:
260 *gen_type = HW_BREAKPOINT_X;
261 break;
262 case X86_BREAKPOINT_WRITE:
263 *gen_type = HW_BREAKPOINT_W;
264 break;
265 case X86_BREAKPOINT_RW:
266 *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
267 break;
268 default:
269 return -EINVAL;
270 }
271
272 return 0;
273}
274
275
276static int arch_build_bp_info(struct perf_event *bp)
277{
278 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
279
280 info->address = bp->attr.bp_addr;
281
282 /* Len */
283 switch (bp->attr.bp_len) {
K.Prasad0067f122009-06-01 23:43:57 +0530284 case HW_BREAKPOINT_LEN_1:
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200285 info->len = X86_BREAKPOINT_LEN_1;
K.Prasad0067f122009-06-01 23:43:57 +0530286 break;
287 case HW_BREAKPOINT_LEN_2:
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200288 info->len = X86_BREAKPOINT_LEN_2;
K.Prasad0067f122009-06-01 23:43:57 +0530289 break;
290 case HW_BREAKPOINT_LEN_4:
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200291 info->len = X86_BREAKPOINT_LEN_4;
K.Prasad0067f122009-06-01 23:43:57 +0530292 break;
293#ifdef CONFIG_X86_64
294 case HW_BREAKPOINT_LEN_8:
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200295 info->len = X86_BREAKPOINT_LEN_8;
296 break;
297#endif
298 default:
299 return -EINVAL;
300 }
301
302 /* Type */
303 switch (bp->attr.bp_type) {
304 case HW_BREAKPOINT_W:
305 info->type = X86_BREAKPOINT_WRITE;
306 break;
307 case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
308 info->type = X86_BREAKPOINT_RW;
309 break;
310 case HW_BREAKPOINT_X:
311 info->type = X86_BREAKPOINT_EXECUTE;
312 break;
313 default:
314 return -EINVAL;
315 }
316
317 return 0;
318}
319/*
320 * Validate the arch-specific HW Breakpoint register settings
321 */
322int arch_validate_hwbkpt_settings(struct perf_event *bp,
323 struct task_struct *tsk)
324{
325 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
326 unsigned int align;
327 int ret;
328
329
330 ret = arch_build_bp_info(bp);
331 if (ret)
332 return ret;
333
334 ret = -EINVAL;
335
336 if (info->type == X86_BREAKPOINT_EXECUTE)
337 /*
338 * Ptrace-refactoring code
339 * For now, we'll allow instruction breakpoint only for user-space
340 * addresses
341 */
342 if ((!arch_check_va_in_userspace(info->address, info->len)) &&
343 info->len != X86_BREAKPOINT_EXECUTE)
344 return ret;
345
346 switch (info->len) {
347 case X86_BREAKPOINT_LEN_1:
348 align = 0;
349 break;
350 case X86_BREAKPOINT_LEN_2:
351 align = 1;
352 break;
353 case X86_BREAKPOINT_LEN_4:
354 align = 3;
355 break;
356#ifdef CONFIG_X86_64
357 case X86_BREAKPOINT_LEN_8:
K.Prasad0067f122009-06-01 23:43:57 +0530358 align = 7;
359 break;
360#endif
361 default:
362 return ret;
363 }
364
Frederic Weisbeckerb326e952009-12-05 09:44:31 +0100365 ret = arch_store_info(bp);
K.Prasad0067f122009-06-01 23:43:57 +0530366
367 if (ret < 0)
368 return ret;
369 /*
370 * Check that the low-order bits of the address are appropriate
371 * for the alignment implied by len.
372 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200373 if (info->address & align)
K.Prasad0067f122009-06-01 23:43:57 +0530374 return -EINVAL;
375
376 /* Check that the virtual address is in the proper range */
377 if (tsk) {
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200378 if (!arch_check_va_in_userspace(info->address, info->len))
K.Prasad0067f122009-06-01 23:43:57 +0530379 return -EFAULT;
380 } else {
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200381 if (!arch_check_va_in_kernelspace(info->address, info->len))
K.Prasad0067f122009-06-01 23:43:57 +0530382 return -EFAULT;
383 }
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200384
K.Prasad0067f122009-06-01 23:43:57 +0530385 return 0;
386}
387
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200388/*
Frederic Weisbecker9f6b3c22009-11-09 21:03:43 +0100389 * Dump the debug register contents to the user.
390 * We can't dump our per cpu values because it
391 * may contain cpu wide breakpoint, something that
392 * doesn't belong to the current task.
393 *
394 * TODO: include non-ptrace user breakpoints (perf)
395 */
396void aout_dump_debugregs(struct user *dump)
397{
398 int i;
399 int dr7 = 0;
400 struct perf_event *bp;
401 struct arch_hw_breakpoint *info;
402 struct thread_struct *thread = &current->thread;
403
404 for (i = 0; i < HBP_NUM; i++) {
405 bp = thread->ptrace_bps[i];
406
407 if (bp && !bp->attr.disabled) {
408 dump->u_debugreg[i] = bp->attr.bp_addr;
409 info = counter_arch_bp(bp);
410 dr7 |= encode_dr7(i, info->len, info->type);
411 } else {
412 dump->u_debugreg[i] = 0;
413 }
414 }
415
416 dump->u_debugreg[4] = 0;
417 dump->u_debugreg[5] = 0;
418 dump->u_debugreg[6] = current->thread.debugreg6;
419
420 dump->u_debugreg[7] = dr7;
421}
Ingo Molnar68efa372009-11-14 01:35:29 +0100422EXPORT_SYMBOL_GPL(aout_dump_debugregs);
Frederic Weisbecker9f6b3c22009-11-09 21:03:43 +0100423
424/*
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200425 * Release the user breakpoints used by ptrace
426 */
427void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
K.Prasad0067f122009-06-01 23:43:57 +0530428{
429 int i;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200430 struct thread_struct *t = &tsk->thread;
K.Prasad0067f122009-06-01 23:43:57 +0530431
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200432 for (i = 0; i < HBP_NUM; i++) {
433 unregister_hw_breakpoint(t->ptrace_bps[i]);
434 t->ptrace_bps[i] = NULL;
435 }
K.Prasad0067f122009-06-01 23:43:57 +0530436}
437
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200438void hw_breakpoint_restore(void)
439{
440 set_debugreg(__get_cpu_var(cpu_debugreg[0]), 0);
441 set_debugreg(__get_cpu_var(cpu_debugreg[1]), 1);
442 set_debugreg(__get_cpu_var(cpu_debugreg[2]), 2);
443 set_debugreg(__get_cpu_var(cpu_debugreg[3]), 3);
444 set_debugreg(current->thread.debugreg6, 6);
Tejun Heo28b4e0d2009-11-25 22:24:44 +0900445 set_debugreg(__get_cpu_var(cpu_dr7), 7);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200446}
447EXPORT_SYMBOL_GPL(hw_breakpoint_restore);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200448
K.Prasad0067f122009-06-01 23:43:57 +0530449/*
450 * Handle debug exception notifications.
451 *
452 * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below.
453 *
454 * NOTIFY_DONE returned if one of the following conditions is true.
455 * i) When the causative address is from user-space and the exception
456 * is a valid one, i.e. not triggered as a result of lazy debug register
457 * switching
458 * ii) When there are more bits than trap<n> set in DR6 register (such
459 * as BD, BS or BT) indicating that more than one debug condition is
460 * met and requires some more action in do_debug().
461 *
462 * NOTIFY_STOP returned for all other cases
463 *
464 */
Jaswinder Singh Rajput45558352009-06-17 14:44:19 +0530465static int __kprobes hw_breakpoint_handler(struct die_args *args)
K.Prasad0067f122009-06-01 23:43:57 +0530466{
467 int i, cpu, rc = NOTIFY_STOP;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200468 struct perf_event *bp;
K.Prasad62edab92009-06-01 23:47:06 +0530469 unsigned long dr7, dr6;
470 unsigned long *dr6_p;
471
472 /* The DR6 value is pointed by args->err */
473 dr6_p = (unsigned long *)ERR_PTR(args->err);
474 dr6 = *dr6_p;
K.Prasad0067f122009-06-01 23:43:57 +0530475
476 /* Do an early return if no trap bits are set in DR6 */
477 if ((dr6 & DR_TRAP_BITS) == 0)
478 return NOTIFY_DONE;
479
K.Prasad0067f122009-06-01 23:43:57 +0530480 get_debugreg(dr7, 7);
481 /* Disable breakpoints during exception handling */
482 set_debugreg(0UL, 7);
483 /*
484 * Assert that local interrupts are disabled
485 * Reset the DRn bits in the virtualized register value.
486 * The ptrace trigger routine will add in whatever is needed.
487 */
488 current->thread.debugreg6 &= ~DR_TRAP_BITS;
489 cpu = get_cpu();
490
491 /* Handle all the breakpoints that were triggered */
492 for (i = 0; i < HBP_NUM; ++i) {
493 if (likely(!(dr6 & (DR_TRAP0 << i))))
494 continue;
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200495
K.Prasad0067f122009-06-01 23:43:57 +0530496 /*
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200497 * The counter may be concurrently released but that can only
498 * occur from a call_rcu() path. We can then safely fetch
499 * the breakpoint, use its callback, touch its counter
500 * while we are in an rcu_read_lock() path.
K.Prasad0067f122009-06-01 23:43:57 +0530501 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200502 rcu_read_lock();
503
504 bp = per_cpu(bp_per_reg[i], cpu);
505 if (bp)
506 rc = NOTIFY_DONE;
K.Prasad0067f122009-06-01 23:43:57 +0530507 /*
K.Prasad62edab92009-06-01 23:47:06 +0530508 * Reset the 'i'th TRAP bit in dr6 to denote completion of
509 * exception handling
510 */
511 (*dr6_p) &= ~(DR_TRAP0 << i);
512 /*
K.Prasad0067f122009-06-01 23:43:57 +0530513 * bp can be NULL due to lazy debug register switching
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200514 * or due to concurrent perf counter removing.
K.Prasad0067f122009-06-01 23:43:57 +0530515 */
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200516 if (!bp) {
517 rcu_read_unlock();
518 break;
519 }
K.Prasad0067f122009-06-01 23:43:57 +0530520
Frederic Weisbeckerb326e952009-12-05 09:44:31 +0100521 perf_bp_event(bp, args->regs);
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200522
523 rcu_read_unlock();
K.Prasad0067f122009-06-01 23:43:57 +0530524 }
525 if (dr6 & (~DR_TRAP_BITS))
526 rc = NOTIFY_DONE;
527
528 set_debugreg(dr7, 7);
Ingo Molnareadb8a02009-06-17 12:52:15 +0200529 put_cpu();
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200530
K.Prasad0067f122009-06-01 23:43:57 +0530531 return rc;
532}
533
534/*
535 * Handle debug exception notifications.
536 */
537int __kprobes hw_breakpoint_exceptions_notify(
538 struct notifier_block *unused, unsigned long val, void *data)
539{
540 if (val != DIE_DEBUG)
541 return NOTIFY_DONE;
542
543 return hw_breakpoint_handler(data);
544}
Frederic Weisbecker24f1e32c2009-09-09 19:22:48 +0200545
546void hw_breakpoint_pmu_read(struct perf_event *bp)
547{
548 /* TODO */
549}
550
551void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
552{
553 /* TODO */
554}