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30#include <linux/perf_event.h>
31#include <linux/hw_breakpoint.h>
32#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
48
49DEFINE_PER_CPU(unsigned long, cpu_dr7);
50EXPORT_PER_CPU_SYMBOL(cpu_dr7);
51
52
53static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]);
54
55
56
57
58
59static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);
60
61
62static 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
74
75
76
77
78unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type)
79{
80 return __encode_dr7(drnum, len, type) | DR_GLOBAL_SLOWDOWN;
81}
82
83
84
85
86
87int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type)
88{
89 int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE);
90
91 *len = (bp_info & 0xc) | 0x40;
92 *type = (bp_info & 0x3) | 0x80;
93
94 return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3;
95}
96
97
98
99
100
101
102
103
104
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;
118 }
119 }
120
121 if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
122 return -EBUSY;
123
124 set_debugreg(info->address, i);
125 __this_cpu_write(cpu_debugreg[i], info->address);
126
127 dr7 = &__get_cpu_var(cpu_dr7);
128 *dr7 |= encode_dr7(i, info->len, info->type);
129
130 set_debugreg(*dr7, 7);
131
132 return 0;
133}
134
135
136
137
138
139
140
141
142
143
144void arch_uninstall_hw_breakpoint(struct perf_event *bp)
145{
146 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
147 unsigned long *dr7;
148 int i;
149
150 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 }
157 }
158
159 if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
160 return;
161
162 dr7 = &__get_cpu_var(cpu_dr7);
163 *dr7 &= ~__encode_dr7(i, info->len, info->type);
164
165 set_debugreg(*dr7, 7);
166}
167
168static int get_hbp_len(u8 hbp_len)
169{
170 unsigned int len_in_bytes = 0;
171
172 switch (hbp_len) {
173 case X86_BREAKPOINT_LEN_1:
174 len_in_bytes = 1;
175 break;
176 case X86_BREAKPOINT_LEN_2:
177 len_in_bytes = 2;
178 break;
179 case X86_BREAKPOINT_LEN_4:
180 len_in_bytes = 4;
181 break;
182#ifdef CONFIG_X86_64
183 case X86_BREAKPOINT_LEN_8:
184 len_in_bytes = 8;
185 break;
186#endif
187 }
188 return len_in_bytes;
189}
190
191
192
193
194int arch_check_bp_in_kernelspace(struct perf_event *bp)
195{
196 unsigned int len;
197 unsigned long va;
198 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
199
200 va = info->address;
201 len = get_hbp_len(info->len);
202
203 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
204}
205
206int arch_bp_generic_fields(int x86_len, int x86_type,
207 int *gen_len, int *gen_type)
208{
209
210 switch (x86_type) {
211 case X86_BREAKPOINT_EXECUTE:
212 if (x86_len != X86_BREAKPOINT_LEN_X)
213 return -EINVAL;
214
215 *gen_type = HW_BREAKPOINT_X;
216 *gen_len = sizeof(long);
217 return 0;
218 case X86_BREAKPOINT_WRITE:
219 *gen_type = HW_BREAKPOINT_W;
220 break;
221 case X86_BREAKPOINT_RW:
222 *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
223 break;
224 default:
225 return -EINVAL;
226 }
227
228
229 switch (x86_len) {
230 case X86_BREAKPOINT_LEN_1:
231 *gen_len = HW_BREAKPOINT_LEN_1;
232 break;
233 case X86_BREAKPOINT_LEN_2:
234 *gen_len = HW_BREAKPOINT_LEN_2;
235 break;
236 case X86_BREAKPOINT_LEN_4:
237 *gen_len = HW_BREAKPOINT_LEN_4;
238 break;
239#ifdef CONFIG_X86_64
240 case X86_BREAKPOINT_LEN_8:
241 *gen_len = HW_BREAKPOINT_LEN_8;
242 break;
243#endif
244 default:
245 return -EINVAL;
246 }
247
248 return 0;
249}
250
251
252static int arch_build_bp_info(struct perf_event *bp)
253{
254 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
255
256 info->address = bp->attr.bp_addr;
257
258
259 switch (bp->attr.bp_type) {
260 case HW_BREAKPOINT_W:
261 info->type = X86_BREAKPOINT_WRITE;
262 break;
263 case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
264 info->type = X86_BREAKPOINT_RW;
265 break;
266 case HW_BREAKPOINT_X:
267 info->type = X86_BREAKPOINT_EXECUTE;
268
269
270
271
272
273 if (bp->attr.bp_len == sizeof(long)) {
274 info->len = X86_BREAKPOINT_LEN_X;
275 return 0;
276 }
277 default:
278 return -EINVAL;
279 }
280
281
282 switch (bp->attr.bp_len) {
283 case HW_BREAKPOINT_LEN_1:
284 info->len = X86_BREAKPOINT_LEN_1;
285 break;
286 case HW_BREAKPOINT_LEN_2:
287 info->len = X86_BREAKPOINT_LEN_2;
288 break;
289 case HW_BREAKPOINT_LEN_4:
290 info->len = X86_BREAKPOINT_LEN_4;
291 break;
292#ifdef CONFIG_X86_64
293 case HW_BREAKPOINT_LEN_8:
294 info->len = X86_BREAKPOINT_LEN_8;
295 break;
296#endif
297 default:
298 return -EINVAL;
299 }
300
301 return 0;
302}
303
304
305
306int arch_validate_hwbkpt_settings(struct perf_event *bp)
307{
308 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
309 unsigned int align;
310 int ret;
311
312
313 ret = arch_build_bp_info(bp);
314 if (ret)
315 return ret;
316
317 ret = -EINVAL;
318
319 switch (info->len) {
320 case X86_BREAKPOINT_LEN_1:
321 align = 0;
322 break;
323 case X86_BREAKPOINT_LEN_2:
324 align = 1;
325 break;
326 case X86_BREAKPOINT_LEN_4:
327 align = 3;
328 break;
329#ifdef CONFIG_X86_64
330 case X86_BREAKPOINT_LEN_8:
331 align = 7;
332 break;
333#endif
334 default:
335 return ret;
336 }
337
338
339
340
341
342 if (info->address & align)
343 return -EINVAL;
344
345 return 0;
346}
347
348
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352
353
354
355
356void aout_dump_debugregs(struct user *dump)
357{
358 int i;
359 int dr7 = 0;
360 struct perf_event *bp;
361 struct arch_hw_breakpoint *info;
362 struct thread_struct *thread = ¤t->thread;
363
364 for (i = 0; i < HBP_NUM; i++) {
365 bp = thread->ptrace_bps[i];
366
367 if (bp && !bp->attr.disabled) {
368 dump->u_debugreg[i] = bp->attr.bp_addr;
369 info = counter_arch_bp(bp);
370 dr7 |= encode_dr7(i, info->len, info->type);
371 } else {
372 dump->u_debugreg[i] = 0;
373 }
374 }
375
376 dump->u_debugreg[4] = 0;
377 dump->u_debugreg[5] = 0;
378 dump->u_debugreg[6] = current->thread.debugreg6;
379
380 dump->u_debugreg[7] = dr7;
381}
382EXPORT_SYMBOL_GPL(aout_dump_debugregs);
383
384
385
386
387void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
388{
389 int i;
390 struct thread_struct *t = &tsk->thread;
391
392 for (i = 0; i < HBP_NUM; i++) {
393 unregister_hw_breakpoint(t->ptrace_bps[i]);
394 t->ptrace_bps[i] = NULL;
395 }
396
397 t->debugreg6 = 0;
398 t->ptrace_dr7 = 0;
399}
400
401void hw_breakpoint_restore(void)
402{
403 set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0);
404 set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1);
405 set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2);
406 set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3);
407 set_debugreg(current->thread.debugreg6, 6);
408 set_debugreg(__this_cpu_read(cpu_dr7), 7);
409}
410EXPORT_SYMBOL_GPL(hw_breakpoint_restore);
411
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425
426
427
428static int __kprobes hw_breakpoint_handler(struct die_args *args)
429{
430 int i, cpu, rc = NOTIFY_STOP;
431 struct perf_event *bp;
432 unsigned long dr7, dr6;
433 unsigned long *dr6_p;
434
435
436 dr6_p = (unsigned long *)ERR_PTR(args->err);
437 dr6 = *dr6_p;
438
439
440 if (dr6 & DR_STEP)
441 return NOTIFY_DONE;
442
443
444 if ((dr6 & DR_TRAP_BITS) == 0)
445 return NOTIFY_DONE;
446
447 get_debugreg(dr7, 7);
448
449 set_debugreg(0UL, 7);
450
451
452
453
454
455 current->thread.debugreg6 &= ~DR_TRAP_BITS;
456 cpu = get_cpu();
457
458
459 for (i = 0; i < HBP_NUM; ++i) {
460 if (likely(!(dr6 & (DR_TRAP0 << i))))
461 continue;
462
463
464
465
466
467
468
469 rcu_read_lock();
470
471 bp = per_cpu(bp_per_reg[i], cpu);
472
473
474
475
476 (*dr6_p) &= ~(DR_TRAP0 << i);
477
478
479
480
481 if (!bp) {
482 rcu_read_unlock();
483 break;
484 }
485
486 perf_bp_event(bp, args->regs);
487
488
489
490
491
492 if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE)
493 args->regs->flags |= X86_EFLAGS_RF;
494
495 rcu_read_unlock();
496 }
497
498
499
500
501
502 if ((current->thread.debugreg6 & DR_TRAP_BITS) ||
503 (dr6 & (~DR_TRAP_BITS)))
504 rc = NOTIFY_DONE;
505
506 set_debugreg(dr7, 7);
507 put_cpu();
508
509 return rc;
510}
511
512
513
514
515int __kprobes hw_breakpoint_exceptions_notify(
516 struct notifier_block *unused, unsigned long val, void *data)
517{
518 if (val != DIE_DEBUG)
519 return NOTIFY_DONE;
520
521 return hw_breakpoint_handler(data);
522}
523
524void hw_breakpoint_pmu_read(struct perf_event *bp)
525{
526
527}
528