1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25#include <linux/hw_breakpoint.h>
26#include <linux/notifier.h>
27#include <linux/kprobes.h>
28#include <linux/percpu.h>
29#include <linux/kernel.h>
30#include <linux/sched.h>
31#include <linux/init.h>
32#include <linux/smp.h>
33
34#include <asm/hw_breakpoint.h>
35#include <asm/processor.h>
36#include <asm/sstep.h>
37#include <asm/uaccess.h>
38
39
40
41
42
43static DEFINE_PER_CPU(struct perf_event *, bp_per_reg);
44
45
46
47
48int hw_breakpoint_slots(int type)
49{
50 if (type == TYPE_DATA)
51 return HBP_NUM;
52 return 0;
53}
54
55
56
57
58
59
60
61
62
63
64int arch_install_hw_breakpoint(struct perf_event *bp)
65{
66 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
67 struct perf_event **slot = &__get_cpu_var(bp_per_reg);
68
69 *slot = bp;
70
71
72
73
74
75 if (current->thread.last_hit_ubp != bp)
76 set_breakpoint(info);
77
78 return 0;
79}
80
81
82
83
84
85
86
87
88
89
90void arch_uninstall_hw_breakpoint(struct perf_event *bp)
91{
92 struct perf_event **slot = &__get_cpu_var(bp_per_reg);
93
94 if (*slot != bp) {
95 WARN_ONCE(1, "Can't find the breakpoint");
96 return;
97 }
98
99 *slot = NULL;
100 hw_breakpoint_disable();
101}
102
103
104
105
106
107void arch_unregister_hw_breakpoint(struct perf_event *bp)
108{
109
110
111
112
113
114 if (bp->ctx && bp->ctx->task)
115 bp->ctx->task->thread.last_hit_ubp = NULL;
116}
117
118
119
120
121int arch_check_bp_in_kernelspace(struct perf_event *bp)
122{
123 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
124
125 return is_kernel_addr(info->address);
126}
127
128int arch_bp_generic_fields(int type, int *gen_bp_type)
129{
130 *gen_bp_type = 0;
131 if (type & HW_BRK_TYPE_READ)
132 *gen_bp_type |= HW_BREAKPOINT_R;
133 if (type & HW_BRK_TYPE_WRITE)
134 *gen_bp_type |= HW_BREAKPOINT_W;
135 if (*gen_bp_type == 0)
136 return -EINVAL;
137 return 0;
138}
139
140
141
142
143int arch_validate_hwbkpt_settings(struct perf_event *bp)
144{
145 int ret = -EINVAL, length_max;
146 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
147
148 if (!bp)
149 return ret;
150
151 info->type = HW_BRK_TYPE_TRANSLATE;
152 if (bp->attr.bp_type & HW_BREAKPOINT_R)
153 info->type |= HW_BRK_TYPE_READ;
154 if (bp->attr.bp_type & HW_BREAKPOINT_W)
155 info->type |= HW_BRK_TYPE_WRITE;
156 if (info->type == HW_BRK_TYPE_TRANSLATE)
157
158 return ret;
159 if (!(bp->attr.exclude_user))
160 info->type |= HW_BRK_TYPE_USER;
161 if (!(bp->attr.exclude_kernel))
162 info->type |= HW_BRK_TYPE_KERNEL;
163 if (!(bp->attr.exclude_hv))
164 info->type |= HW_BRK_TYPE_HYP;
165 info->address = bp->attr.bp_addr;
166 info->len = bp->attr.bp_len;
167
168
169
170
171
172
173
174 length_max = 8;
175 if (cpu_has_feature(CPU_FTR_DAWR)) {
176 length_max = 512 ;
177
178 if ((bp->attr.bp_addr >> 10) !=
179 ((bp->attr.bp_addr + bp->attr.bp_len) >> 10))
180 return -EINVAL;
181 }
182 if (info->len >
183 (length_max - (info->address & HW_BREAKPOINT_ALIGN)))
184 return -EINVAL;
185 return 0;
186}
187
188
189
190
191
192
193void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
194{
195 struct arch_hw_breakpoint *info;
196
197 if (likely(!tsk->thread.last_hit_ubp))
198 return;
199
200 info = counter_arch_bp(tsk->thread.last_hit_ubp);
201 regs->msr &= ~MSR_SE;
202 set_breakpoint(info);
203 tsk->thread.last_hit_ubp = NULL;
204}
205
206
207
208
209int __kprobes hw_breakpoint_handler(struct die_args *args)
210{
211 int rc = NOTIFY_STOP;
212 struct perf_event *bp;
213 struct pt_regs *regs = args->regs;
214 int stepped = 1;
215 struct arch_hw_breakpoint *info;
216 unsigned int instr;
217 unsigned long dar = regs->dar;
218
219
220 hw_breakpoint_disable();
221
222
223
224
225
226
227
228 rcu_read_lock();
229
230 bp = __get_cpu_var(bp_per_reg);
231 if (!bp)
232 goto out;
233 info = counter_arch_bp(bp);
234
235
236
237
238
239
240
241 if (bp->overflow_handler == ptrace_triggered) {
242 perf_bp_event(bp, regs);
243 rc = NOTIFY_DONE;
244 goto out;
245 }
246
247
248
249
250
251
252
253 if (!((bp->attr.bp_addr <= dar) &&
254 (dar - bp->attr.bp_addr < bp->attr.bp_len)))
255 info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
256
257
258 if (user_mode(regs)) {
259 current->thread.last_hit_ubp = bp;
260 regs->msr |= MSR_SE;
261 goto out;
262 }
263
264 stepped = 0;
265 instr = 0;
266 if (!__get_user_inatomic(instr, (unsigned int *) regs->nip))
267 stepped = emulate_step(regs, instr);
268
269
270
271
272
273
274 if (!stepped) {
275 WARN(1, "Unable to handle hardware breakpoint. Breakpoint at "
276 "0x%lx will be disabled.", info->address);
277 perf_event_disable(bp);
278 goto out;
279 }
280
281
282
283
284 if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
285 perf_bp_event(bp, regs);
286
287 set_breakpoint(info);
288out:
289 rcu_read_unlock();
290 return rc;
291}
292
293
294
295
296int __kprobes single_step_dabr_instruction(struct die_args *args)
297{
298 struct pt_regs *regs = args->regs;
299 struct perf_event *bp = NULL;
300 struct arch_hw_breakpoint *info;
301
302 bp = current->thread.last_hit_ubp;
303
304
305
306
307 if (!bp)
308 return NOTIFY_DONE;
309
310 info = counter_arch_bp(bp);
311
312
313
314
315
316 if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
317 perf_bp_event(bp, regs);
318
319 set_breakpoint(info);
320 current->thread.last_hit_ubp = NULL;
321
322
323
324
325
326 if (test_thread_flag(TIF_SINGLESTEP))
327 return NOTIFY_DONE;
328
329 return NOTIFY_STOP;
330}
331
332
333
334
335int __kprobes hw_breakpoint_exceptions_notify(
336 struct notifier_block *unused, unsigned long val, void *data)
337{
338 int ret = NOTIFY_DONE;
339
340 switch (val) {
341 case DIE_DABR_MATCH:
342 ret = hw_breakpoint_handler(data);
343 break;
344 case DIE_SSTEP:
345 ret = single_step_dabr_instruction(data);
346 break;
347 }
348
349 return ret;
350}
351
352
353
354
355void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
356{
357 struct thread_struct *t = &tsk->thread;
358
359 unregister_hw_breakpoint(t->ptrace_bps[0]);
360 t->ptrace_bps[0] = NULL;
361}
362
363void hw_breakpoint_pmu_read(struct perf_event *bp)
364{
365
366}
367