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-rw-r--r--arch/arm64/kernel/hw_breakpoint.c880
1 files changed, 880 insertions, 0 deletions
diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
new file mode 100644
index 000000000000..5ab825c59db9
--- /dev/null
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -0,0 +1,880 @@
1/*
2 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
3 * using the CPU's debug registers.
4 *
5 * Copyright (C) 2012 ARM Limited
6 * Author: Will Deacon <will.deacon@arm.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program. If not, see <http://www.gnu.org/licenses/>.
19 */
20
21#define pr_fmt(fmt) "hw-breakpoint: " fmt
22
23#include <linux/errno.h>
24#include <linux/hw_breakpoint.h>
25#include <linux/perf_event.h>
26#include <linux/ptrace.h>
27#include <linux/smp.h>
28
29#include <asm/compat.h>
30#include <asm/current.h>
31#include <asm/debug-monitors.h>
32#include <asm/hw_breakpoint.h>
33#include <asm/kdebug.h>
34#include <asm/traps.h>
35#include <asm/cputype.h>
36#include <asm/system_misc.h>
37
38/* Breakpoint currently in use for each BRP. */
39static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
40
41/* Watchpoint currently in use for each WRP. */
42static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]);
43
44/* Currently stepping a per-CPU kernel breakpoint. */
45static DEFINE_PER_CPU(int, stepping_kernel_bp);
46
47/* Number of BRP/WRP registers on this CPU. */
48static int core_num_brps;
49static int core_num_wrps;
50
51/* Determine number of BRP registers available. */
52static int get_num_brps(void)
53{
54 return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1;
55}
56
57/* Determine number of WRP registers available. */
58static int get_num_wrps(void)
59{
60 return ((read_cpuid(ID_AA64DFR0_EL1) >> 20) & 0xf) + 1;
61}
62
63int hw_breakpoint_slots(int type)
64{
65 /*
66 * We can be called early, so don't rely on
67 * our static variables being initialised.
68 */
69 switch (type) {
70 case TYPE_INST:
71 return get_num_brps();
72 case TYPE_DATA:
73 return get_num_wrps();
74 default:
75 pr_warning("unknown slot type: %d\n", type);
76 return 0;
77 }
78}
79
80#define READ_WB_REG_CASE(OFF, N, REG, VAL) \
81 case (OFF + N): \
82 AARCH64_DBG_READ(N, REG, VAL); \
83 break
84
85#define WRITE_WB_REG_CASE(OFF, N, REG, VAL) \
86 case (OFF + N): \
87 AARCH64_DBG_WRITE(N, REG, VAL); \
88 break
89
90#define GEN_READ_WB_REG_CASES(OFF, REG, VAL) \
91 READ_WB_REG_CASE(OFF, 0, REG, VAL); \
92 READ_WB_REG_CASE(OFF, 1, REG, VAL); \
93 READ_WB_REG_CASE(OFF, 2, REG, VAL); \
94 READ_WB_REG_CASE(OFF, 3, REG, VAL); \
95 READ_WB_REG_CASE(OFF, 4, REG, VAL); \
96 READ_WB_REG_CASE(OFF, 5, REG, VAL); \
97 READ_WB_REG_CASE(OFF, 6, REG, VAL); \
98 READ_WB_REG_CASE(OFF, 7, REG, VAL); \
99 READ_WB_REG_CASE(OFF, 8, REG, VAL); \
100 READ_WB_REG_CASE(OFF, 9, REG, VAL); \
101 READ_WB_REG_CASE(OFF, 10, REG, VAL); \
102 READ_WB_REG_CASE(OFF, 11, REG, VAL); \
103 READ_WB_REG_CASE(OFF, 12, REG, VAL); \
104 READ_WB_REG_CASE(OFF, 13, REG, VAL); \
105 READ_WB_REG_CASE(OFF, 14, REG, VAL); \
106 READ_WB_REG_CASE(OFF, 15, REG, VAL)
107
108#define GEN_WRITE_WB_REG_CASES(OFF, REG, VAL) \
109 WRITE_WB_REG_CASE(OFF, 0, REG, VAL); \
110 WRITE_WB_REG_CASE(OFF, 1, REG, VAL); \
111 WRITE_WB_REG_CASE(OFF, 2, REG, VAL); \
112 WRITE_WB_REG_CASE(OFF, 3, REG, VAL); \
113 WRITE_WB_REG_CASE(OFF, 4, REG, VAL); \
114 WRITE_WB_REG_CASE(OFF, 5, REG, VAL); \
115 WRITE_WB_REG_CASE(OFF, 6, REG, VAL); \
116 WRITE_WB_REG_CASE(OFF, 7, REG, VAL); \
117 WRITE_WB_REG_CASE(OFF, 8, REG, VAL); \
118 WRITE_WB_REG_CASE(OFF, 9, REG, VAL); \
119 WRITE_WB_REG_CASE(OFF, 10, REG, VAL); \
120 WRITE_WB_REG_CASE(OFF, 11, REG, VAL); \
121 WRITE_WB_REG_CASE(OFF, 12, REG, VAL); \
122 WRITE_WB_REG_CASE(OFF, 13, REG, VAL); \
123 WRITE_WB_REG_CASE(OFF, 14, REG, VAL); \
124 WRITE_WB_REG_CASE(OFF, 15, REG, VAL)
125
126static u64 read_wb_reg(int reg, int n)
127{
128 u64 val = 0;
129
130 switch (reg + n) {
131 GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_BVR, AARCH64_DBG_REG_NAME_BVR, val);
132 GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_BCR, AARCH64_DBG_REG_NAME_BCR, val);
133 GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_WVR, AARCH64_DBG_REG_NAME_WVR, val);
134 GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_WCR, AARCH64_DBG_REG_NAME_WCR, val);
135 default:
136 pr_warning("attempt to read from unknown breakpoint register %d\n", n);
137 }
138
139 return val;
140}
141
142static void write_wb_reg(int reg, int n, u64 val)
143{
144 switch (reg + n) {
145 GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_BVR, AARCH64_DBG_REG_NAME_BVR, val);
146 GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_BCR, AARCH64_DBG_REG_NAME_BCR, val);
147 GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_WVR, AARCH64_DBG_REG_NAME_WVR, val);
148 GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_WCR, AARCH64_DBG_REG_NAME_WCR, val);
149 default:
150 pr_warning("attempt to write to unknown breakpoint register %d\n", n);
151 }
152 isb();
153}
154
155/*
156 * Convert a breakpoint privilege level to the corresponding exception
157 * level.
158 */
159static enum debug_el debug_exception_level(int privilege)
160{
161 switch (privilege) {
162 case AARCH64_BREAKPOINT_EL0:
163 return DBG_ACTIVE_EL0;
164 case AARCH64_BREAKPOINT_EL1:
165 return DBG_ACTIVE_EL1;
166 default:
167 pr_warning("invalid breakpoint privilege level %d\n", privilege);
168 return -EINVAL;
169 }
170}
171
172/*
173 * Install a perf counter breakpoint.
174 */
175int arch_install_hw_breakpoint(struct perf_event *bp)
176{
177 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
178 struct perf_event **slot, **slots;
179 struct debug_info *debug_info = &current->thread.debug;
180 int i, max_slots, ctrl_reg, val_reg, reg_enable;
181 u32 ctrl;
182
183 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
184 /* Breakpoint */
185 ctrl_reg = AARCH64_DBG_REG_BCR;
186 val_reg = AARCH64_DBG_REG_BVR;
187 slots = __get_cpu_var(bp_on_reg);
188 max_slots = core_num_brps;
189 reg_enable = !debug_info->bps_disabled;
190 } else {
191 /* Watchpoint */
192 ctrl_reg = AARCH64_DBG_REG_WCR;
193 val_reg = AARCH64_DBG_REG_WVR;
194 slots = __get_cpu_var(wp_on_reg);
195 max_slots = core_num_wrps;
196 reg_enable = !debug_info->wps_disabled;
197 }
198
199 for (i = 0; i < max_slots; ++i) {
200 slot = &slots[i];
201
202 if (!*slot) {
203 *slot = bp;
204 break;
205 }
206 }
207
208 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot"))
209 return -ENOSPC;
210
211 /* Ensure debug monitors are enabled at the correct exception level. */
212 enable_debug_monitors(debug_exception_level(info->ctrl.privilege));
213
214 /* Setup the address register. */
215 write_wb_reg(val_reg, i, info->address);
216
217 /* Setup the control register. */
218 ctrl = encode_ctrl_reg(info->ctrl);
219 write_wb_reg(ctrl_reg, i, reg_enable ? ctrl | 0x1 : ctrl & ~0x1);
220
221 return 0;
222}
223
224void arch_uninstall_hw_breakpoint(struct perf_event *bp)
225{
226 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
227 struct perf_event **slot, **slots;
228 int i, max_slots, base;
229
230 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
231 /* Breakpoint */
232 base = AARCH64_DBG_REG_BCR;
233 slots = __get_cpu_var(bp_on_reg);
234 max_slots = core_num_brps;
235 } else {
236 /* Watchpoint */
237 base = AARCH64_DBG_REG_WCR;
238 slots = __get_cpu_var(wp_on_reg);
239 max_slots = core_num_wrps;
240 }
241
242 /* Remove the breakpoint. */
243 for (i = 0; i < max_slots; ++i) {
244 slot = &slots[i];
245
246 if (*slot == bp) {
247 *slot = NULL;
248 break;
249 }
250 }
251
252 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot"))
253 return;
254
255 /* Reset the control register. */
256 write_wb_reg(base, i, 0);
257
258 /* Release the debug monitors for the correct exception level. */
259 disable_debug_monitors(debug_exception_level(info->ctrl.privilege));
260}
261
262static int get_hbp_len(u8 hbp_len)
263{
264 unsigned int len_in_bytes = 0;
265
266 switch (hbp_len) {
267 case ARM_BREAKPOINT_LEN_1:
268 len_in_bytes = 1;
269 break;
270 case ARM_BREAKPOINT_LEN_2:
271 len_in_bytes = 2;
272 break;
273 case ARM_BREAKPOINT_LEN_4:
274 len_in_bytes = 4;
275 break;
276 case ARM_BREAKPOINT_LEN_8:
277 len_in_bytes = 8;
278 break;
279 }
280
281 return len_in_bytes;
282}
283
284/*
285 * Check whether bp virtual address is in kernel space.
286 */
287int arch_check_bp_in_kernelspace(struct perf_event *bp)
288{
289 unsigned int len;
290 unsigned long va;
291 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
292
293 va = info->address;
294 len = get_hbp_len(info->ctrl.len);
295
296 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
297}
298
299/*
300 * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
301 * Hopefully this will disappear when ptrace can bypass the conversion
302 * to generic breakpoint descriptions.
303 */
304int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
305 int *gen_len, int *gen_type)
306{
307 /* Type */
308 switch (ctrl.type) {
309 case ARM_BREAKPOINT_EXECUTE:
310 *gen_type = HW_BREAKPOINT_X;
311 break;
312 case ARM_BREAKPOINT_LOAD:
313 *gen_type = HW_BREAKPOINT_R;
314 break;
315 case ARM_BREAKPOINT_STORE:
316 *gen_type = HW_BREAKPOINT_W;
317 break;
318 case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE:
319 *gen_type = HW_BREAKPOINT_RW;
320 break;
321 default:
322 return -EINVAL;
323 }
324
325 /* Len */
326 switch (ctrl.len) {
327 case ARM_BREAKPOINT_LEN_1:
328 *gen_len = HW_BREAKPOINT_LEN_1;
329 break;
330 case ARM_BREAKPOINT_LEN_2:
331 *gen_len = HW_BREAKPOINT_LEN_2;
332 break;
333 case ARM_BREAKPOINT_LEN_4:
334 *gen_len = HW_BREAKPOINT_LEN_4;
335 break;
336 case ARM_BREAKPOINT_LEN_8:
337 *gen_len = HW_BREAKPOINT_LEN_8;
338 break;
339 default:
340 return -EINVAL;
341 }
342
343 return 0;
344}
345
346/*
347 * Construct an arch_hw_breakpoint from a perf_event.
348 */
349static int arch_build_bp_info(struct perf_event *bp)
350{
351 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
352
353 /* Type */
354 switch (bp->attr.bp_type) {
355 case HW_BREAKPOINT_X:
356 info->ctrl.type = ARM_BREAKPOINT_EXECUTE;
357 break;
358 case HW_BREAKPOINT_R:
359 info->ctrl.type = ARM_BREAKPOINT_LOAD;
360 break;
361 case HW_BREAKPOINT_W:
362 info->ctrl.type = ARM_BREAKPOINT_STORE;
363 break;
364 case HW_BREAKPOINT_RW:
365 info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
366 break;
367 default:
368 return -EINVAL;
369 }
370
371 /* Len */
372 switch (bp->attr.bp_len) {
373 case HW_BREAKPOINT_LEN_1:
374 info->ctrl.len = ARM_BREAKPOINT_LEN_1;
375 break;
376 case HW_BREAKPOINT_LEN_2:
377 info->ctrl.len = ARM_BREAKPOINT_LEN_2;
378 break;
379 case HW_BREAKPOINT_LEN_4:
380 info->ctrl.len = ARM_BREAKPOINT_LEN_4;
381 break;
382 case HW_BREAKPOINT_LEN_8:
383 info->ctrl.len = ARM_BREAKPOINT_LEN_8;
384 break;
385 default:
386 return -EINVAL;
387 }
388
389 /*
390 * On AArch64, we only permit breakpoints of length 4, whereas
391 * AArch32 also requires breakpoints of length 2 for Thumb.
392 * Watchpoints can be of length 1, 2, 4 or 8 bytes.
393 */
394 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
395 if (is_compat_task()) {
396 if (info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
397 info->ctrl.len != ARM_BREAKPOINT_LEN_4)
398 return -EINVAL;
399 } else if (info->ctrl.len != ARM_BREAKPOINT_LEN_4) {
400 /*
401 * FIXME: Some tools (I'm looking at you perf) assume
402 * that breakpoints should be sizeof(long). This
403 * is nonsense. For now, we fix up the parameter
404 * but we should probably return -EINVAL instead.
405 */
406 info->ctrl.len = ARM_BREAKPOINT_LEN_4;
407 }
408 }
409
410 /* Address */
411 info->address = bp->attr.bp_addr;
412
413 /*
414 * Privilege
415 * Note that we disallow combined EL0/EL1 breakpoints because
416 * that would complicate the stepping code.
417 */
418 if (arch_check_bp_in_kernelspace(bp))
419 info->ctrl.privilege = AARCH64_BREAKPOINT_EL1;
420 else
421 info->ctrl.privilege = AARCH64_BREAKPOINT_EL0;
422
423 /* Enabled? */
424 info->ctrl.enabled = !bp->attr.disabled;
425
426 return 0;
427}
428
429/*
430 * Validate the arch-specific HW Breakpoint register settings.
431 */
432int arch_validate_hwbkpt_settings(struct perf_event *bp)
433{
434 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
435 int ret;
436 u64 alignment_mask, offset;
437
438 /* Build the arch_hw_breakpoint. */
439 ret = arch_build_bp_info(bp);
440 if (ret)
441 return ret;
442
443 /*
444 * Check address alignment.
445 * We don't do any clever alignment correction for watchpoints
446 * because using 64-bit unaligned addresses is deprecated for
447 * AArch64.
448 *
449 * AArch32 tasks expect some simple alignment fixups, so emulate
450 * that here.
451 */
452 if (is_compat_task()) {
453 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
454 alignment_mask = 0x7;
455 else
456 alignment_mask = 0x3;
457 offset = info->address & alignment_mask;
458 switch (offset) {
459 case 0:
460 /* Aligned */
461 break;
462 case 1:
463 /* Allow single byte watchpoint. */
464 if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
465 break;
466 case 2:
467 /* Allow halfword watchpoints and breakpoints. */
468 if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
469 break;
470 default:
471 return -EINVAL;
472 }
473
474 info->address &= ~alignment_mask;
475 info->ctrl.len <<= offset;
476 } else {
477 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE)
478 alignment_mask = 0x3;
479 else
480 alignment_mask = 0x7;
481 if (info->address & alignment_mask)
482 return -EINVAL;
483 }
484
485 /*
486 * Disallow per-task kernel breakpoints since these would
487 * complicate the stepping code.
488 */
489 if (info->ctrl.privilege == AARCH64_BREAKPOINT_EL1 && bp->hw.bp_target)
490 return -EINVAL;
491
492 return 0;
493}
494
495/*
496 * Enable/disable all of the breakpoints active at the specified
497 * exception level at the register level.
498 * This is used when single-stepping after a breakpoint exception.
499 */
500static void toggle_bp_registers(int reg, enum debug_el el, int enable)
501{
502 int i, max_slots, privilege;
503 u32 ctrl;
504 struct perf_event **slots;
505
506 switch (reg) {
507 case AARCH64_DBG_REG_BCR:
508 slots = __get_cpu_var(bp_on_reg);
509 max_slots = core_num_brps;
510 break;
511 case AARCH64_DBG_REG_WCR:
512 slots = __get_cpu_var(wp_on_reg);
513 max_slots = core_num_wrps;
514 break;
515 default:
516 return;
517 }
518
519 for (i = 0; i < max_slots; ++i) {
520 if (!slots[i])
521 continue;
522
523 privilege = counter_arch_bp(slots[i])->ctrl.privilege;
524 if (debug_exception_level(privilege) != el)
525 continue;
526
527 ctrl = read_wb_reg(reg, i);
528 if (enable)
529 ctrl |= 0x1;
530 else
531 ctrl &= ~0x1;
532 write_wb_reg(reg, i, ctrl);
533 }
534}
535
536/*
537 * Debug exception handlers.
538 */
539static int breakpoint_handler(unsigned long unused, unsigned int esr,
540 struct pt_regs *regs)
541{
542 int i, step = 0, *kernel_step;
543 u32 ctrl_reg;
544 u64 addr, val;
545 struct perf_event *bp, **slots;
546 struct debug_info *debug_info;
547 struct arch_hw_breakpoint_ctrl ctrl;
548
549 slots = (struct perf_event **)__get_cpu_var(bp_on_reg);
550 addr = instruction_pointer(regs);
551 debug_info = &current->thread.debug;
552
553 for (i = 0; i < core_num_brps; ++i) {
554 rcu_read_lock();
555
556 bp = slots[i];
557
558 if (bp == NULL)
559 goto unlock;
560
561 /* Check if the breakpoint value matches. */
562 val = read_wb_reg(AARCH64_DBG_REG_BVR, i);
563 if (val != (addr & ~0x3))
564 goto unlock;
565
566 /* Possible match, check the byte address select to confirm. */
567 ctrl_reg = read_wb_reg(AARCH64_DBG_REG_BCR, i);
568 decode_ctrl_reg(ctrl_reg, &ctrl);
569 if (!((1 << (addr & 0x3)) & ctrl.len))
570 goto unlock;
571
572 counter_arch_bp(bp)->trigger = addr;
573 perf_bp_event(bp, regs);
574
575 /* Do we need to handle the stepping? */
576 if (!bp->overflow_handler)
577 step = 1;
578unlock:
579 rcu_read_unlock();
580 }
581
582 if (!step)
583 return 0;
584
585 if (user_mode(regs)) {
586 debug_info->bps_disabled = 1;
587 toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL0, 0);
588
589 /* If we're already stepping a watchpoint, just return. */
590 if (debug_info->wps_disabled)
591 return 0;
592
593 if (test_thread_flag(TIF_SINGLESTEP))
594 debug_info->suspended_step = 1;
595 else
596 user_enable_single_step(current);
597 } else {
598 toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL1, 0);
599 kernel_step = &__get_cpu_var(stepping_kernel_bp);
600
601 if (*kernel_step != ARM_KERNEL_STEP_NONE)
602 return 0;
603
604 if (kernel_active_single_step()) {
605 *kernel_step = ARM_KERNEL_STEP_SUSPEND;
606 } else {
607 *kernel_step = ARM_KERNEL_STEP_ACTIVE;
608 kernel_enable_single_step(regs);
609 }
610 }
611
612 return 0;
613}
614
615static int watchpoint_handler(unsigned long addr, unsigned int esr,
616 struct pt_regs *regs)
617{
618 int i, step = 0, *kernel_step, access;
619 u32 ctrl_reg;
620 u64 val, alignment_mask;
621 struct perf_event *wp, **slots;
622 struct debug_info *debug_info;
623 struct arch_hw_breakpoint *info;
624 struct arch_hw_breakpoint_ctrl ctrl;
625
626 slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
627 debug_info = &current->thread.debug;
628
629 for (i = 0; i < core_num_wrps; ++i) {
630 rcu_read_lock();
631
632 wp = slots[i];
633
634 if (wp == NULL)
635 goto unlock;
636
637 info = counter_arch_bp(wp);
638 /* AArch32 watchpoints are either 4 or 8 bytes aligned. */
639 if (is_compat_task()) {
640 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
641 alignment_mask = 0x7;
642 else
643 alignment_mask = 0x3;
644 } else {
645 alignment_mask = 0x7;
646 }
647
648 /* Check if the watchpoint value matches. */
649 val = read_wb_reg(AARCH64_DBG_REG_WVR, i);
650 if (val != (addr & ~alignment_mask))
651 goto unlock;
652
653 /* Possible match, check the byte address select to confirm. */
654 ctrl_reg = read_wb_reg(AARCH64_DBG_REG_WCR, i);
655 decode_ctrl_reg(ctrl_reg, &ctrl);
656 if (!((1 << (addr & alignment_mask)) & ctrl.len))
657 goto unlock;
658
659 /*
660 * Check that the access type matches.
661 * 0 => load, otherwise => store
662 */
663 access = (esr & AARCH64_ESR_ACCESS_MASK) ? HW_BREAKPOINT_W :
664 HW_BREAKPOINT_R;
665 if (!(access & hw_breakpoint_type(wp)))
666 goto unlock;
667
668 info->trigger = addr;
669 perf_bp_event(wp, regs);
670
671 /* Do we need to handle the stepping? */
672 if (!wp->overflow_handler)
673 step = 1;
674
675unlock:
676 rcu_read_unlock();
677 }
678
679 if (!step)
680 return 0;
681
682 /*
683 * We always disable EL0 watchpoints because the kernel can
684 * cause these to fire via an unprivileged access.
685 */
686 toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 0);
687
688 if (user_mode(regs)) {
689 debug_info->wps_disabled = 1;
690
691 /* If we're already stepping a breakpoint, just return. */
692 if (debug_info->bps_disabled)
693 return 0;
694
695 if (test_thread_flag(TIF_SINGLESTEP))
696 debug_info->suspended_step = 1;
697 else
698 user_enable_single_step(current);
699 } else {
700 toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL1, 0);
701 kernel_step = &__get_cpu_var(stepping_kernel_bp);
702
703 if (*kernel_step != ARM_KERNEL_STEP_NONE)
704 return 0;
705
706 if (kernel_active_single_step()) {
707 *kernel_step = ARM_KERNEL_STEP_SUSPEND;
708 } else {
709 *kernel_step = ARM_KERNEL_STEP_ACTIVE;
710 kernel_enable_single_step(regs);
711 }
712 }
713
714 return 0;
715}
716
717/*
718 * Handle single-step exception.
719 */
720int reinstall_suspended_bps(struct pt_regs *regs)
721{
722 struct debug_info *debug_info = &current->thread.debug;
723 int handled_exception = 0, *kernel_step;
724
725 kernel_step = &__get_cpu_var(stepping_kernel_bp);
726
727 /*
728 * Called from single-step exception handler.
729 * Return 0 if execution can resume, 1 if a SIGTRAP should be
730 * reported.
731 */
732 if (user_mode(regs)) {
733 if (debug_info->bps_disabled) {
734 debug_info->bps_disabled = 0;
735 toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL0, 1);
736 handled_exception = 1;
737 }
738
739 if (debug_info->wps_disabled) {
740 debug_info->wps_disabled = 0;
741 toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1);
742 handled_exception = 1;
743 }
744
745 if (handled_exception) {
746 if (debug_info->suspended_step) {
747 debug_info->suspended_step = 0;
748 /* Allow exception handling to fall-through. */
749 handled_exception = 0;
750 } else {
751 user_disable_single_step(current);
752 }
753 }
754 } else if (*kernel_step != ARM_KERNEL_STEP_NONE) {
755 toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL1, 1);
756 toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL1, 1);
757
758 if (!debug_info->wps_disabled)
759 toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1);
760
761 if (*kernel_step != ARM_KERNEL_STEP_SUSPEND) {
762 kernel_disable_single_step();
763 handled_exception = 1;
764 } else {
765 handled_exception = 0;
766 }
767
768 *kernel_step = ARM_KERNEL_STEP_NONE;
769 }
770
771 return !handled_exception;
772}
773
774/*
775 * Context-switcher for restoring suspended breakpoints.
776 */
777void hw_breakpoint_thread_switch(struct task_struct *next)
778{
779 /*
780 * current next
781 * disabled: 0 0 => The usual case, NOTIFY_DONE
782 * 0 1 => Disable the registers
783 * 1 0 => Enable the registers
784 * 1 1 => NOTIFY_DONE. per-task bps will
785 * get taken care of by perf.
786 */
787
788 struct debug_info *current_debug_info, *next_debug_info;
789
790 current_debug_info = &current->thread.debug;
791 next_debug_info = &next->thread.debug;
792
793 /* Update breakpoints. */
794 if (current_debug_info->bps_disabled != next_debug_info->bps_disabled)
795 toggle_bp_registers(AARCH64_DBG_REG_BCR,
796 DBG_ACTIVE_EL0,
797 !next_debug_info->bps_disabled);
798
799 /* Update watchpoints. */
800 if (current_debug_info->wps_disabled != next_debug_info->wps_disabled)
801 toggle_bp_registers(AARCH64_DBG_REG_WCR,
802 DBG_ACTIVE_EL0,
803 !next_debug_info->wps_disabled);
804}
805
806/*
807 * CPU initialisation.
808 */
809static void reset_ctrl_regs(void *unused)
810{
811 int i;
812
813 for (i = 0; i < core_num_brps; ++i) {
814 write_wb_reg(AARCH64_DBG_REG_BCR, i, 0UL);
815 write_wb_reg(AARCH64_DBG_REG_BVR, i, 0UL);
816 }
817
818 for (i = 0; i < core_num_wrps; ++i) {
819 write_wb_reg(AARCH64_DBG_REG_WCR, i, 0UL);
820 write_wb_reg(AARCH64_DBG_REG_WVR, i, 0UL);
821 }
822}
823
824static int __cpuinit hw_breakpoint_reset_notify(struct notifier_block *self,
825 unsigned long action,
826 void *hcpu)
827{
828 int cpu = (long)hcpu;
829 if (action == CPU_ONLINE)
830 smp_call_function_single(cpu, reset_ctrl_regs, NULL, 1);
831 return NOTIFY_OK;
832}
833
834static struct notifier_block __cpuinitdata hw_breakpoint_reset_nb = {
835 .notifier_call = hw_breakpoint_reset_notify,
836};
837
838/*
839 * One-time initialisation.
840 */
841static int __init arch_hw_breakpoint_init(void)
842{
843 core_num_brps = get_num_brps();
844 core_num_wrps = get_num_wrps();
845
846 pr_info("found %d breakpoint and %d watchpoint registers.\n",
847 core_num_brps, core_num_wrps);
848
849 /*
850 * Reset the breakpoint resources. We assume that a halting
851 * debugger will leave the world in a nice state for us.
852 */
853 smp_call_function(reset_ctrl_regs, NULL, 1);
854 reset_ctrl_regs(NULL);
855
856 /* Register debug fault handlers. */
857 hook_debug_fault_code(DBG_ESR_EVT_HWBP, breakpoint_handler, SIGTRAP,
858 TRAP_HWBKPT, "hw-breakpoint handler");
859 hook_debug_fault_code(DBG_ESR_EVT_HWWP, watchpoint_handler, SIGTRAP,
860 TRAP_HWBKPT, "hw-watchpoint handler");
861
862 /* Register hotplug notifier. */
863 register_cpu_notifier(&hw_breakpoint_reset_nb);
864
865 return 0;
866}
867arch_initcall(arch_hw_breakpoint_init);
868
869void hw_breakpoint_pmu_read(struct perf_event *bp)
870{
871}
872
873/*
874 * Dummy function to register with die_notifier.
875 */
876int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
877 unsigned long val, void *data)
878{
879 return NOTIFY_DONE;
880}
generated by cgit v1.2.2 (git 2.25.0) at 2026-01-07 12:43:34 -0500