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1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License version 2 as
4 * published by the Free Software Foundation.
5 *
6 * This program is distributed in the hope that it will be useful,
7 * but WITHOUT ANY WARRANTY; without even the implied warranty of
8 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
9 * GNU General Public License for more details.
10 *
11 * You should have received a copy of the GNU General Public License
12 * along with this program; if not, write to the Free Software
13 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
14 *
15 * Copyright (C) 2009, 2010 ARM Limited
16 *
17 * Author: Will Deacon <will.deacon@arm.com>
18 */
19
20/*
21 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
22 * using the CPU's debug registers.
23 */
24#define pr_fmt(fmt) "hw-breakpoint: " fmt
25
26#include <linux/errno.h>
27#include <linux/hardirq.h>
28#include <linux/perf_event.h>
29#include <linux/hw_breakpoint.h>
30#include <linux/smp.h>
31#include <linux/cpu_pm.h>
32
33#include <asm/cacheflush.h>
34#include <asm/cputype.h>
35#include <asm/current.h>
36#include <asm/hw_breakpoint.h>
37#include <asm/kdebug.h>
38#include <asm/traps.h>
39#include <asm/hardware/coresight.h>
40
41/* Breakpoint currently in use for each BRP. */
42static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
43
44/* Watchpoint currently in use for each WRP. */
45static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]);
46
47/* Number of BRP/WRP registers on this CPU. */
48static int core_num_brps;
49static int core_num_wrps;
50
51/* Debug architecture version. */
52static u8 debug_arch;
53
54/* Does debug architecture support OS Save and Restore? */
55static bool has_ossr;
56
57/* Maximum supported watchpoint length. */
58static u8 max_watchpoint_len;
59
60#define READ_WB_REG_CASE(OP2, M, VAL) \
61 case ((OP2 << 4) + M): \
62 ARM_DBG_READ(c0, c ## M, OP2, VAL); \
63 break
64
65#define WRITE_WB_REG_CASE(OP2, M, VAL) \
66 case ((OP2 << 4) + M): \
67 ARM_DBG_WRITE(c0, c ## M, OP2, VAL); \
68 break
69
70#define GEN_READ_WB_REG_CASES(OP2, VAL) \
71 READ_WB_REG_CASE(OP2, 0, VAL); \
72 READ_WB_REG_CASE(OP2, 1, VAL); \
73 READ_WB_REG_CASE(OP2, 2, VAL); \
74 READ_WB_REG_CASE(OP2, 3, VAL); \
75 READ_WB_REG_CASE(OP2, 4, VAL); \
76 READ_WB_REG_CASE(OP2, 5, VAL); \
77 READ_WB_REG_CASE(OP2, 6, VAL); \
78 READ_WB_REG_CASE(OP2, 7, VAL); \
79 READ_WB_REG_CASE(OP2, 8, VAL); \
80 READ_WB_REG_CASE(OP2, 9, VAL); \
81 READ_WB_REG_CASE(OP2, 10, VAL); \
82 READ_WB_REG_CASE(OP2, 11, VAL); \
83 READ_WB_REG_CASE(OP2, 12, VAL); \
84 READ_WB_REG_CASE(OP2, 13, VAL); \
85 READ_WB_REG_CASE(OP2, 14, VAL); \
86 READ_WB_REG_CASE(OP2, 15, VAL)
87
88#define GEN_WRITE_WB_REG_CASES(OP2, VAL) \
89 WRITE_WB_REG_CASE(OP2, 0, VAL); \
90 WRITE_WB_REG_CASE(OP2, 1, VAL); \
91 WRITE_WB_REG_CASE(OP2, 2, VAL); \
92 WRITE_WB_REG_CASE(OP2, 3, VAL); \
93 WRITE_WB_REG_CASE(OP2, 4, VAL); \
94 WRITE_WB_REG_CASE(OP2, 5, VAL); \
95 WRITE_WB_REG_CASE(OP2, 6, VAL); \
96 WRITE_WB_REG_CASE(OP2, 7, VAL); \
97 WRITE_WB_REG_CASE(OP2, 8, VAL); \
98 WRITE_WB_REG_CASE(OP2, 9, VAL); \
99 WRITE_WB_REG_CASE(OP2, 10, VAL); \
100 WRITE_WB_REG_CASE(OP2, 11, VAL); \
101 WRITE_WB_REG_CASE(OP2, 12, VAL); \
102 WRITE_WB_REG_CASE(OP2, 13, VAL); \
103 WRITE_WB_REG_CASE(OP2, 14, VAL); \
104 WRITE_WB_REG_CASE(OP2, 15, VAL)
105
106static u32 read_wb_reg(int n)
107{
108 u32 val = 0;
109
110 switch (n) {
111 GEN_READ_WB_REG_CASES(ARM_OP2_BVR, val);
112 GEN_READ_WB_REG_CASES(ARM_OP2_BCR, val);
113 GEN_READ_WB_REG_CASES(ARM_OP2_WVR, val);
114 GEN_READ_WB_REG_CASES(ARM_OP2_WCR, val);
115 default:
116 pr_warning("attempt to read from unknown breakpoint "
117 "register %d\n", n);
118 }
119
120 return val;
121}
122
123static void write_wb_reg(int n, u32 val)
124{
125 switch (n) {
126 GEN_WRITE_WB_REG_CASES(ARM_OP2_BVR, val);
127 GEN_WRITE_WB_REG_CASES(ARM_OP2_BCR, val);
128 GEN_WRITE_WB_REG_CASES(ARM_OP2_WVR, val);
129 GEN_WRITE_WB_REG_CASES(ARM_OP2_WCR, val);
130 default:
131 pr_warning("attempt to write to unknown breakpoint "
132 "register %d\n", n);
133 }
134 isb();
135}
136
137/* Determine debug architecture. */
138static u8 get_debug_arch(void)
139{
140 u32 didr;
141
142 /* Do we implement the extended CPUID interface? */
143 if (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
144 pr_warn_once("CPUID feature registers not supported. "
145 "Assuming v6 debug is present.\n");
146 return ARM_DEBUG_ARCH_V6;
147 }
148
149 ARM_DBG_READ(c0, c0, 0, didr);
150 return (didr >> 16) & 0xf;
151}
152
153u8 arch_get_debug_arch(void)
154{
155 return debug_arch;
156}
157
158static int debug_arch_supported(void)
159{
160 u8 arch = get_debug_arch();
161
162 /* We don't support the memory-mapped interface. */
163 return (arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14) ||
164 arch >= ARM_DEBUG_ARCH_V7_1;
165}
166
167/* Can we determine the watchpoint access type from the fsr? */
168static int debug_exception_updates_fsr(void)
169{
170 return get_debug_arch() >= ARM_DEBUG_ARCH_V8;
171}
172
173/* Determine number of WRP registers available. */
174static int get_num_wrp_resources(void)
175{
176 u32 didr;
177 ARM_DBG_READ(c0, c0, 0, didr);
178 return ((didr >> 28) & 0xf) + 1;
179}
180
181/* Determine number of BRP registers available. */
182static int get_num_brp_resources(void)
183{
184 u32 didr;
185 ARM_DBG_READ(c0, c0, 0, didr);
186 return ((didr >> 24) & 0xf) + 1;
187}
188
189/* Does this core support mismatch breakpoints? */
190static int core_has_mismatch_brps(void)
191{
192 return (get_debug_arch() >= ARM_DEBUG_ARCH_V7_ECP14 &&
193 get_num_brp_resources() > 1);
194}
195
196/* Determine number of usable WRPs available. */
197static int get_num_wrps(void)
198{
199 /*
200 * On debug architectures prior to 7.1, when a watchpoint fires, the
201 * only way to work out which watchpoint it was is by disassembling
202 * the faulting instruction and working out the address of the memory
203 * access.
204 *
205 * Furthermore, we can only do this if the watchpoint was precise
206 * since imprecise watchpoints prevent us from calculating register
207 * based addresses.
208 *
209 * Providing we have more than 1 breakpoint register, we only report
210 * a single watchpoint register for the time being. This way, we always
211 * know which watchpoint fired. In the future we can either add a
212 * disassembler and address generation emulator, or we can insert a
213 * check to see if the DFAR is set on watchpoint exception entry
214 * [the ARM ARM states that the DFAR is UNKNOWN, but experience shows
215 * that it is set on some implementations].
216 */
217 if (get_debug_arch() < ARM_DEBUG_ARCH_V7_1)
218 return 1;
219
220 return get_num_wrp_resources();
221}
222
223/* Determine number of usable BRPs available. */
224static int get_num_brps(void)
225{
226 int brps = get_num_brp_resources();
227 return core_has_mismatch_brps() ? brps - 1 : brps;
228}
229
230/*
231 * In order to access the breakpoint/watchpoint control registers,
232 * we must be running in debug monitor mode. Unfortunately, we can
233 * be put into halting debug mode at any time by an external debugger
234 * but there is nothing we can do to prevent that.
235 */
236static int monitor_mode_enabled(void)
237{
238 u32 dscr;
239 ARM_DBG_READ(c0, c1, 0, dscr);
240 return !!(dscr & ARM_DSCR_MDBGEN);
241}
242
243static int enable_monitor_mode(void)
244{
245 u32 dscr;
246 ARM_DBG_READ(c0, c1, 0, dscr);
247
248 /* If monitor mode is already enabled, just return. */
249 if (dscr & ARM_DSCR_MDBGEN)
250 goto out;
251
252 /* Write to the corresponding DSCR. */
253 switch (get_debug_arch()) {
254 case ARM_DEBUG_ARCH_V6:
255 case ARM_DEBUG_ARCH_V6_1:
256 ARM_DBG_WRITE(c0, c1, 0, (dscr | ARM_DSCR_MDBGEN));
257 break;
258 case ARM_DEBUG_ARCH_V7_ECP14:
259 case ARM_DEBUG_ARCH_V7_1:
260 case ARM_DEBUG_ARCH_V8:
261 ARM_DBG_WRITE(c0, c2, 2, (dscr | ARM_DSCR_MDBGEN));
262 isb();
263 break;
264 default:
265 return -ENODEV;
266 }
267
268 /* Check that the write made it through. */
269 ARM_DBG_READ(c0, c1, 0, dscr);
270 if (!(dscr & ARM_DSCR_MDBGEN)) {
271 pr_warn_once("Failed to enable monitor mode on CPU %d.\n",
272 smp_processor_id());
273 return -EPERM;
274 }
275
276out:
277 return 0;
278}
279
280int hw_breakpoint_slots(int type)
281{
282 if (!debug_arch_supported())
283 return 0;
284
285 /*
286 * We can be called early, so don't rely on
287 * our static variables being initialised.
288 */
289 switch (type) {
290 case TYPE_INST:
291 return get_num_brps();
292 case TYPE_DATA:
293 return get_num_wrps();
294 default:
295 pr_warning("unknown slot type: %d\n", type);
296 return 0;
297 }
298}
299
300/*
301 * Check if 8-bit byte-address select is available.
302 * This clobbers WRP 0.
303 */
304static u8 get_max_wp_len(void)
305{
306 u32 ctrl_reg;
307 struct arch_hw_breakpoint_ctrl ctrl;
308 u8 size = 4;
309
310 if (debug_arch < ARM_DEBUG_ARCH_V7_ECP14)
311 goto out;
312
313 memset(&ctrl, 0, sizeof(ctrl));
314 ctrl.len = ARM_BREAKPOINT_LEN_8;
315 ctrl_reg = encode_ctrl_reg(ctrl);
316
317 write_wb_reg(ARM_BASE_WVR, 0);
318 write_wb_reg(ARM_BASE_WCR, ctrl_reg);
319 if ((read_wb_reg(ARM_BASE_WCR) & ctrl_reg) == ctrl_reg)
320 size = 8;
321
322out:
323 return size;
324}
325
326u8 arch_get_max_wp_len(void)
327{
328 return max_watchpoint_len;
329}
330
331/*
332 * Install a perf counter breakpoint.
333 */
334int arch_install_hw_breakpoint(struct perf_event *bp)
335{
336 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
337 struct perf_event **slot, **slots;
338 int i, max_slots, ctrl_base, val_base;
339 u32 addr, ctrl;
340
341 addr = info->address;
342 ctrl = encode_ctrl_reg(info->ctrl) | 0x1;
343
344 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
345 /* Breakpoint */
346 ctrl_base = ARM_BASE_BCR;
347 val_base = ARM_BASE_BVR;
348 slots = this_cpu_ptr(bp_on_reg);
349 max_slots = core_num_brps;
350 } else {
351 /* Watchpoint */
352 ctrl_base = ARM_BASE_WCR;
353 val_base = ARM_BASE_WVR;
354 slots = this_cpu_ptr(wp_on_reg);
355 max_slots = core_num_wrps;
356 }
357
358 for (i = 0; i < max_slots; ++i) {
359 slot = &slots[i];
360
361 if (!*slot) {
362 *slot = bp;
363 break;
364 }
365 }
366
367 if (i == max_slots) {
368 pr_warning("Can't find any breakpoint slot\n");
369 return -EBUSY;
370 }
371
372 /* Override the breakpoint data with the step data. */
373 if (info->step_ctrl.enabled) {
374 addr = info->trigger & ~0x3;
375 ctrl = encode_ctrl_reg(info->step_ctrl);
376 if (info->ctrl.type != ARM_BREAKPOINT_EXECUTE) {
377 i = 0;
378 ctrl_base = ARM_BASE_BCR + core_num_brps;
379 val_base = ARM_BASE_BVR + core_num_brps;
380 }
381 }
382
383 /* Setup the address register. */
384 write_wb_reg(val_base + i, addr);
385
386 /* Setup the control register. */
387 write_wb_reg(ctrl_base + i, ctrl);
388 return 0;
389}
390
391void arch_uninstall_hw_breakpoint(struct perf_event *bp)
392{
393 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
394 struct perf_event **slot, **slots;
395 int i, max_slots, base;
396
397 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
398 /* Breakpoint */
399 base = ARM_BASE_BCR;
400 slots = this_cpu_ptr(bp_on_reg);
401 max_slots = core_num_brps;
402 } else {
403 /* Watchpoint */
404 base = ARM_BASE_WCR;
405 slots = this_cpu_ptr(wp_on_reg);
406 max_slots = core_num_wrps;
407 }
408
409 /* Remove the breakpoint. */
410 for (i = 0; i < max_slots; ++i) {
411 slot = &slots[i];
412
413 if (*slot == bp) {
414 *slot = NULL;
415 break;
416 }
417 }
418
419 if (i == max_slots) {
420 pr_warning("Can't find any breakpoint slot\n");
421 return;
422 }
423
424 /* Ensure that we disable the mismatch breakpoint. */
425 if (info->ctrl.type != ARM_BREAKPOINT_EXECUTE &&
426 info->step_ctrl.enabled) {
427 i = 0;
428 base = ARM_BASE_BCR + core_num_brps;
429 }
430
431 /* Reset the control register. */
432 write_wb_reg(base + i, 0);
433}
434
435static int get_hbp_len(u8 hbp_len)
436{
437 unsigned int len_in_bytes = 0;
438
439 switch (hbp_len) {
440 case ARM_BREAKPOINT_LEN_1:
441 len_in_bytes = 1;
442 break;
443 case ARM_BREAKPOINT_LEN_2:
444 len_in_bytes = 2;
445 break;
446 case ARM_BREAKPOINT_LEN_4:
447 len_in_bytes = 4;
448 break;
449 case ARM_BREAKPOINT_LEN_8:
450 len_in_bytes = 8;
451 break;
452 }
453
454 return len_in_bytes;
455}
456
457/*
458 * Check whether bp virtual address is in kernel space.
459 */
460int arch_check_bp_in_kernelspace(struct perf_event *bp)
461{
462 unsigned int len;
463 unsigned long va;
464 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
465
466 va = info->address;
467 len = get_hbp_len(info->ctrl.len);
468
469 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
470}
471
472/*
473 * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
474 * Hopefully this will disappear when ptrace can bypass the conversion
475 * to generic breakpoint descriptions.
476 */
477int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
478 int *gen_len, int *gen_type)
479{
480 /* Type */
481 switch (ctrl.type) {
482 case ARM_BREAKPOINT_EXECUTE:
483 *gen_type = HW_BREAKPOINT_X;
484 break;
485 case ARM_BREAKPOINT_LOAD:
486 *gen_type = HW_BREAKPOINT_R;
487 break;
488 case ARM_BREAKPOINT_STORE:
489 *gen_type = HW_BREAKPOINT_W;
490 break;
491 case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE:
492 *gen_type = HW_BREAKPOINT_RW;
493 break;
494 default:
495 return -EINVAL;
496 }
497
498 /* Len */
499 switch (ctrl.len) {
500 case ARM_BREAKPOINT_LEN_1:
501 *gen_len = HW_BREAKPOINT_LEN_1;
502 break;
503 case ARM_BREAKPOINT_LEN_2:
504 *gen_len = HW_BREAKPOINT_LEN_2;
505 break;
506 case ARM_BREAKPOINT_LEN_4:
507 *gen_len = HW_BREAKPOINT_LEN_4;
508 break;
509 case ARM_BREAKPOINT_LEN_8:
510 *gen_len = HW_BREAKPOINT_LEN_8;
511 break;
512 default:
513 return -EINVAL;
514 }
515
516 return 0;
517}
518
519/*
520 * Construct an arch_hw_breakpoint from a perf_event.
521 */
522static int arch_build_bp_info(struct perf_event *bp)
523{
524 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
525
526 /* Type */
527 switch (bp->attr.bp_type) {
528 case HW_BREAKPOINT_X:
529 info->ctrl.type = ARM_BREAKPOINT_EXECUTE;
530 break;
531 case HW_BREAKPOINT_R:
532 info->ctrl.type = ARM_BREAKPOINT_LOAD;
533 break;
534 case HW_BREAKPOINT_W:
535 info->ctrl.type = ARM_BREAKPOINT_STORE;
536 break;
537 case HW_BREAKPOINT_RW:
538 info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
539 break;
540 default:
541 return -EINVAL;
542 }
543
544 /* Len */
545 switch (bp->attr.bp_len) {
546 case HW_BREAKPOINT_LEN_1:
547 info->ctrl.len = ARM_BREAKPOINT_LEN_1;
548 break;
549 case HW_BREAKPOINT_LEN_2:
550 info->ctrl.len = ARM_BREAKPOINT_LEN_2;
551 break;
552 case HW_BREAKPOINT_LEN_4:
553 info->ctrl.len = ARM_BREAKPOINT_LEN_4;
554 break;
555 case HW_BREAKPOINT_LEN_8:
556 info->ctrl.len = ARM_BREAKPOINT_LEN_8;
557 if ((info->ctrl.type != ARM_BREAKPOINT_EXECUTE)
558 && max_watchpoint_len >= 8)
559 break;
560 default:
561 return -EINVAL;
562 }
563
564 /*
565 * Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes.
566 * Watchpoints can be of length 1, 2, 4 or 8 bytes if supported
567 * by the hardware and must be aligned to the appropriate number of
568 * bytes.
569 */
570 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE &&
571 info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
572 info->ctrl.len != ARM_BREAKPOINT_LEN_4)
573 return -EINVAL;
574
575 /* Address */
576 info->address = bp->attr.bp_addr;
577
578 /* Privilege */
579 info->ctrl.privilege = ARM_BREAKPOINT_USER;
580 if (arch_check_bp_in_kernelspace(bp))
581 info->ctrl.privilege |= ARM_BREAKPOINT_PRIV;
582
583 /* Enabled? */
584 info->ctrl.enabled = !bp->attr.disabled;
585
586 /* Mismatch */
587 info->ctrl.mismatch = 0;
588
589 return 0;
590}
591
592/*
593 * Validate the arch-specific HW Breakpoint register settings.
594 */
595int arch_validate_hwbkpt_settings(struct perf_event *bp)
596{
597 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
598 int ret = 0;
599 u32 offset, alignment_mask = 0x3;
600
601 /* Ensure that we are in monitor debug mode. */
602 if (!monitor_mode_enabled())
603 return -ENODEV;
604
605 /* Build the arch_hw_breakpoint. */
606 ret = arch_build_bp_info(bp);
607 if (ret)
608 goto out;
609
610 /* Check address alignment. */
611 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
612 alignment_mask = 0x7;
613 offset = info->address & alignment_mask;
614 switch (offset) {
615 case 0:
616 /* Aligned */
617 break;
618 case 1:
619 case 2:
620 /* Allow halfword watchpoints and breakpoints. */
621 if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
622 break;
623 case 3:
624 /* Allow single byte watchpoint. */
625 if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
626 break;
627 default:
628 ret = -EINVAL;
629 goto out;
630 }
631
632 info->address &= ~alignment_mask;
633 info->ctrl.len <<= offset;
634
635 if (!bp->overflow_handler) {
636 /*
637 * Mismatch breakpoints are required for single-stepping
638 * breakpoints.
639 */
640 if (!core_has_mismatch_brps())
641 return -EINVAL;
642
643 /* We don't allow mismatch breakpoints in kernel space. */
644 if (arch_check_bp_in_kernelspace(bp))
645 return -EPERM;
646
647 /*
648 * Per-cpu breakpoints are not supported by our stepping
649 * mechanism.
650 */
651 if (!bp->hw.bp_target)
652 return -EINVAL;
653
654 /*
655 * We only support specific access types if the fsr
656 * reports them.
657 */
658 if (!debug_exception_updates_fsr() &&
659 (info->ctrl.type == ARM_BREAKPOINT_LOAD ||
660 info->ctrl.type == ARM_BREAKPOINT_STORE))
661 return -EINVAL;
662 }
663
664out:
665 return ret;
666}
667
668/*
669 * Enable/disable single-stepping over the breakpoint bp at address addr.
670 */
671static void enable_single_step(struct perf_event *bp, u32 addr)
672{
673 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
674
675 arch_uninstall_hw_breakpoint(bp);
676 info->step_ctrl.mismatch = 1;
677 info->step_ctrl.len = ARM_BREAKPOINT_LEN_4;
678 info->step_ctrl.type = ARM_BREAKPOINT_EXECUTE;
679 info->step_ctrl.privilege = info->ctrl.privilege;
680 info->step_ctrl.enabled = 1;
681 info->trigger = addr;
682 arch_install_hw_breakpoint(bp);
683}
684
685static void disable_single_step(struct perf_event *bp)
686{
687 arch_uninstall_hw_breakpoint(bp);
688 counter_arch_bp(bp)->step_ctrl.enabled = 0;
689 arch_install_hw_breakpoint(bp);
690}
691
692static void watchpoint_handler(unsigned long addr, unsigned int fsr,
693 struct pt_regs *regs)
694{
695 int i, access;
696 u32 val, ctrl_reg, alignment_mask;
697 struct perf_event *wp, **slots;
698 struct arch_hw_breakpoint *info;
699 struct arch_hw_breakpoint_ctrl ctrl;
700
701 slots = this_cpu_ptr(wp_on_reg);
702
703 for (i = 0; i < core_num_wrps; ++i) {
704 rcu_read_lock();
705
706 wp = slots[i];
707
708 if (wp == NULL)
709 goto unlock;
710
711 info = counter_arch_bp(wp);
712 /*
713 * The DFAR is an unknown value on debug architectures prior
714 * to 7.1. Since we only allow a single watchpoint on these
715 * older CPUs, we can set the trigger to the lowest possible
716 * faulting address.
717 */
718 if (debug_arch < ARM_DEBUG_ARCH_V7_1) {
719 BUG_ON(i > 0);
720 info->trigger = wp->attr.bp_addr;
721 } else {
722 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
723 alignment_mask = 0x7;
724 else
725 alignment_mask = 0x3;
726
727 /* Check if the watchpoint value matches. */
728 val = read_wb_reg(ARM_BASE_WVR + i);
729 if (val != (addr & ~alignment_mask))
730 goto unlock;
731
732 /* Possible match, check the byte address select. */
733 ctrl_reg = read_wb_reg(ARM_BASE_WCR + i);
734 decode_ctrl_reg(ctrl_reg, &ctrl);
735 if (!((1 << (addr & alignment_mask)) & ctrl.len))
736 goto unlock;
737
738 /* Check that the access type matches. */
739 if (debug_exception_updates_fsr()) {
740 access = (fsr & ARM_FSR_ACCESS_MASK) ?
741 HW_BREAKPOINT_W : HW_BREAKPOINT_R;
742 if (!(access & hw_breakpoint_type(wp)))
743 goto unlock;
744 }
745
746 /* We have a winner. */
747 info->trigger = addr;
748 }
749
750 pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
751 perf_bp_event(wp, regs);
752
753 /*
754 * If no overflow handler is present, insert a temporary
755 * mismatch breakpoint so we can single-step over the
756 * watchpoint trigger.
757 */
758 if (!wp->overflow_handler)
759 enable_single_step(wp, instruction_pointer(regs));
760
761unlock:
762 rcu_read_unlock();
763 }
764}
765
766static void watchpoint_single_step_handler(unsigned long pc)
767{
768 int i;
769 struct perf_event *wp, **slots;
770 struct arch_hw_breakpoint *info;
771
772 slots = this_cpu_ptr(wp_on_reg);
773
774 for (i = 0; i < core_num_wrps; ++i) {
775 rcu_read_lock();
776
777 wp = slots[i];
778
779 if (wp == NULL)
780 goto unlock;
781
782 info = counter_arch_bp(wp);
783 if (!info->step_ctrl.enabled)
784 goto unlock;
785
786 /*
787 * Restore the original watchpoint if we've completed the
788 * single-step.
789 */
790 if (info->trigger != pc)
791 disable_single_step(wp);
792
793unlock:
794 rcu_read_unlock();
795 }
796}
797
798static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
799{
800 int i;
801 u32 ctrl_reg, val, addr;
802 struct perf_event *bp, **slots;
803 struct arch_hw_breakpoint *info;
804 struct arch_hw_breakpoint_ctrl ctrl;
805
806 slots = this_cpu_ptr(bp_on_reg);
807
808 /* The exception entry code places the amended lr in the PC. */
809 addr = regs->ARM_pc;
810
811 /* Check the currently installed breakpoints first. */
812 for (i = 0; i < core_num_brps; ++i) {
813 rcu_read_lock();
814
815 bp = slots[i];
816
817 if (bp == NULL)
818 goto unlock;
819
820 info = counter_arch_bp(bp);
821
822 /* Check if the breakpoint value matches. */
823 val = read_wb_reg(ARM_BASE_BVR + i);
824 if (val != (addr & ~0x3))
825 goto mismatch;
826
827 /* Possible match, check the byte address select to confirm. */
828 ctrl_reg = read_wb_reg(ARM_BASE_BCR + i);
829 decode_ctrl_reg(ctrl_reg, &ctrl);
830 if ((1 << (addr & 0x3)) & ctrl.len) {
831 info->trigger = addr;
832 pr_debug("breakpoint fired: address = 0x%x\n", addr);
833 perf_bp_event(bp, regs);
834 if (!bp->overflow_handler)
835 enable_single_step(bp, addr);
836 goto unlock;
837 }
838
839mismatch:
840 /* If we're stepping a breakpoint, it can now be restored. */
841 if (info->step_ctrl.enabled)
842 disable_single_step(bp);
843unlock:
844 rcu_read_unlock();
845 }
846
847 /* Handle any pending watchpoint single-step breakpoints. */
848 watchpoint_single_step_handler(addr);
849}
850
851/*
852 * Called from either the Data Abort Handler [watchpoint] or the
853 * Prefetch Abort Handler [breakpoint] with interrupts disabled.
854 */
855static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
856 struct pt_regs *regs)
857{
858 int ret = 0;
859 u32 dscr;
860
861 preempt_disable();
862
863 if (interrupts_enabled(regs))
864 local_irq_enable();
865
866 /* We only handle watchpoints and hardware breakpoints. */
867 ARM_DBG_READ(c0, c1, 0, dscr);
868
869 /* Perform perf callbacks. */
870 switch (ARM_DSCR_MOE(dscr)) {
871 case ARM_ENTRY_BREAKPOINT:
872 breakpoint_handler(addr, regs);
873 break;
874 case ARM_ENTRY_ASYNC_WATCHPOINT:
875 WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
876 case ARM_ENTRY_SYNC_WATCHPOINT:
877 watchpoint_handler(addr, fsr, regs);
878 break;
879 default:
880 ret = 1; /* Unhandled fault. */
881 }
882
883 preempt_enable();
884
885 return ret;
886}
887
888/*
889 * One-time initialisation.
890 */
891static cpumask_t debug_err_mask;
892
893static int debug_reg_trap(struct pt_regs *regs, unsigned int instr)
894{
895 int cpu = smp_processor_id();
896
897 pr_warning("Debug register access (0x%x) caused undefined instruction on CPU %d\n",
898 instr, cpu);
899
900 /* Set the error flag for this CPU and skip the faulting instruction. */
901 cpumask_set_cpu(cpu, &debug_err_mask);
902 instruction_pointer(regs) += 4;
903 return 0;
904}
905
906static struct undef_hook debug_reg_hook = {
907 .instr_mask = 0x0fe80f10,
908 .instr_val = 0x0e000e10,
909 .fn = debug_reg_trap,
910};
911
912/* Does this core support OS Save and Restore? */
913static bool core_has_os_save_restore(void)
914{
915 u32 oslsr;
916
917 switch (get_debug_arch()) {
918 case ARM_DEBUG_ARCH_V7_1:
919 return true;
920 case ARM_DEBUG_ARCH_V7_ECP14:
921 ARM_DBG_READ(c1, c1, 4, oslsr);
922 if (oslsr & ARM_OSLSR_OSLM0)
923 return true;
924 default:
925 return false;
926 }
927}
928
929static void reset_ctrl_regs(void *unused)
930{
931 int i, raw_num_brps, err = 0, cpu = smp_processor_id();
932 u32 val;
933
934 /*
935 * v7 debug contains save and restore registers so that debug state
936 * can be maintained across low-power modes without leaving the debug
937 * logic powered up. It is IMPLEMENTATION DEFINED whether we can access
938 * the debug registers out of reset, so we must unlock the OS Lock
939 * Access Register to avoid taking undefined instruction exceptions
940 * later on.
941 */
942 switch (debug_arch) {
943 case ARM_DEBUG_ARCH_V6:
944 case ARM_DEBUG_ARCH_V6_1:
945 /* ARMv6 cores clear the registers out of reset. */
946 goto out_mdbgen;
947 case ARM_DEBUG_ARCH_V7_ECP14:
948 /*
949 * Ensure sticky power-down is clear (i.e. debug logic is
950 * powered up).
951 */
952 ARM_DBG_READ(c1, c5, 4, val);
953 if ((val & 0x1) == 0)
954 err = -EPERM;
955
956 if (!has_ossr)
957 goto clear_vcr;
958 break;
959 case ARM_DEBUG_ARCH_V7_1:
960 /*
961 * Ensure the OS double lock is clear.
962 */
963 ARM_DBG_READ(c1, c3, 4, val);
964 if ((val & 0x1) == 1)
965 err = -EPERM;
966 break;
967 }
968
969 if (err) {
970 pr_warn_once("CPU %d debug is powered down!\n", cpu);
971 cpumask_or(&debug_err_mask, &debug_err_mask, cpumask_of(cpu));
972 return;
973 }
974
975 /*
976 * Unconditionally clear the OS lock by writing a value
977 * other than CS_LAR_KEY to the access register.
978 */
979 ARM_DBG_WRITE(c1, c0, 4, ~CS_LAR_KEY);
980 isb();
981
982 /*
983 * Clear any configured vector-catch events before
984 * enabling monitor mode.
985 */
986clear_vcr:
987 ARM_DBG_WRITE(c0, c7, 0, 0);
988 isb();
989
990 if (cpumask_intersects(&debug_err_mask, cpumask_of(cpu))) {
991 pr_warn_once("CPU %d failed to disable vector catch\n", cpu);
992 return;
993 }
994
995 /*
996 * The control/value register pairs are UNKNOWN out of reset so
997 * clear them to avoid spurious debug events.
998 */
999 raw_num_brps = get_num_brp_resources();
1000 for (i = 0; i < raw_num_brps; ++i) {
1001 write_wb_reg(ARM_BASE_BCR + i, 0UL);
1002 write_wb_reg(ARM_BASE_BVR + i, 0UL);
1003 }
1004
1005 for (i = 0; i < core_num_wrps; ++i) {
1006 write_wb_reg(ARM_BASE_WCR + i, 0UL);
1007 write_wb_reg(ARM_BASE_WVR + i, 0UL);
1008 }
1009
1010 if (cpumask_intersects(&debug_err_mask, cpumask_of(cpu))) {
1011 pr_warn_once("CPU %d failed to clear debug register pairs\n", cpu);
1012 return;
1013 }
1014
1015 /*
1016 * Have a crack at enabling monitor mode. We don't actually need
1017 * it yet, but reporting an error early is useful if it fails.
1018 */
1019out_mdbgen:
1020 if (enable_monitor_mode())
1021 cpumask_or(&debug_err_mask, &debug_err_mask, cpumask_of(cpu));
1022}
1023
1024static int dbg_reset_notify(struct notifier_block *self,
1025 unsigned long action, void *cpu)
1026{
1027 if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE)
1028 smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
1029
1030 return NOTIFY_OK;
1031}
1032
1033static struct notifier_block dbg_reset_nb = {
1034 .notifier_call = dbg_reset_notify,
1035};
1036
1037#ifdef CONFIG_CPU_PM
1038static int dbg_cpu_pm_notify(struct notifier_block *self, unsigned long action,
1039 void *v)
1040{
1041 if (action == CPU_PM_EXIT)
1042 reset_ctrl_regs(NULL);
1043
1044 return NOTIFY_OK;
1045}
1046
1047static struct notifier_block dbg_cpu_pm_nb = {
1048 .notifier_call = dbg_cpu_pm_notify,
1049};
1050
1051static void __init pm_init(void)
1052{
1053 cpu_pm_register_notifier(&dbg_cpu_pm_nb);
1054}
1055#else
1056static inline void pm_init(void)
1057{
1058}
1059#endif
1060
1061static int __init arch_hw_breakpoint_init(void)
1062{
1063 debug_arch = get_debug_arch();
1064
1065 if (!debug_arch_supported()) {
1066 pr_info("debug architecture 0x%x unsupported.\n", debug_arch);
1067 return 0;
1068 }
1069
1070 has_ossr = core_has_os_save_restore();
1071
1072 /* Determine how many BRPs/WRPs are available. */
1073 core_num_brps = get_num_brps();
1074 core_num_wrps = get_num_wrps();
1075
1076 cpu_notifier_register_begin();
1077
1078 /*
1079 * We need to tread carefully here because DBGSWENABLE may be
1080 * driven low on this core and there isn't an architected way to
1081 * determine that.
1082 */
1083 register_undef_hook(&debug_reg_hook);
1084
1085 /*
1086 * Reset the breakpoint resources. We assume that a halting
1087 * debugger will leave the world in a nice state for us.
1088 */
1089 on_each_cpu(reset_ctrl_regs, NULL, 1);
1090 unregister_undef_hook(&debug_reg_hook);
1091 if (!cpumask_empty(&debug_err_mask)) {
1092 core_num_brps = 0;
1093 core_num_wrps = 0;
1094 cpu_notifier_register_done();
1095 return 0;
1096 }
1097
1098 pr_info("found %d " "%s" "breakpoint and %d watchpoint registers.\n",
1099 core_num_brps, core_has_mismatch_brps() ? "(+1 reserved) " :
1100 "", core_num_wrps);
1101
1102 /* Work out the maximum supported watchpoint length. */
1103 max_watchpoint_len = get_max_wp_len();
1104 pr_info("maximum watchpoint size is %u bytes.\n",
1105 max_watchpoint_len);
1106
1107 /* Register debug fault handler. */
1108 hook_fault_code(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,
1109 TRAP_HWBKPT, "watchpoint debug exception");
1110 hook_ifault_code(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,
1111 TRAP_HWBKPT, "breakpoint debug exception");
1112
1113 /* Register hotplug and PM notifiers. */
1114 __register_cpu_notifier(&dbg_reset_nb);
1115
1116 cpu_notifier_register_done();
1117
1118 pm_init();
1119 return 0;
1120}
1121arch_initcall(arch_hw_breakpoint_init);
1122
1123void hw_breakpoint_pmu_read(struct perf_event *bp)
1124{
1125}
1126
1127/*
1128 * Dummy function to register with die_notifier.
1129 */
1130int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
1131 unsigned long val, void *data)
1132{
1133 return NOTIFY_DONE;
1134}
1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License version 2 as
4 * published by the Free Software Foundation.
5 *
6 * This program is distributed in the hope that it will be useful,
7 * but WITHOUT ANY WARRANTY; without even the implied warranty of
8 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
9 * GNU General Public License for more details.
10 *
11 * You should have received a copy of the GNU General Public License
12 * along with this program; if not, write to the Free Software
13 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
14 *
15 * Copyright (C) 2009, 2010 ARM Limited
16 *
17 * Author: Will Deacon <will.deacon@arm.com>
18 */
19
20/*
21 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
22 * using the CPU's debug registers.
23 */
24#define pr_fmt(fmt) "hw-breakpoint: " fmt
25
26#include <linux/errno.h>
27#include <linux/hardirq.h>
28#include <linux/perf_event.h>
29#include <linux/hw_breakpoint.h>
30#include <linux/smp.h>
31
32#include <asm/cacheflush.h>
33#include <asm/cputype.h>
34#include <asm/current.h>
35#include <asm/hw_breakpoint.h>
36#include <asm/kdebug.h>
37#include <asm/traps.h>
38
39/* Breakpoint currently in use for each BRP. */
40static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
41
42/* Watchpoint currently in use for each WRP. */
43static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]);
44
45/* Number of BRP/WRP registers on this CPU. */
46static int core_num_brps;
47static int core_num_wrps;
48
49/* Debug architecture version. */
50static u8 debug_arch;
51
52/* Maximum supported watchpoint length. */
53static u8 max_watchpoint_len;
54
55#define READ_WB_REG_CASE(OP2, M, VAL) \
56 case ((OP2 << 4) + M): \
57 ARM_DBG_READ(c ## M, OP2, VAL); \
58 break
59
60#define WRITE_WB_REG_CASE(OP2, M, VAL) \
61 case ((OP2 << 4) + M): \
62 ARM_DBG_WRITE(c ## M, OP2, VAL);\
63 break
64
65#define GEN_READ_WB_REG_CASES(OP2, VAL) \
66 READ_WB_REG_CASE(OP2, 0, VAL); \
67 READ_WB_REG_CASE(OP2, 1, VAL); \
68 READ_WB_REG_CASE(OP2, 2, VAL); \
69 READ_WB_REG_CASE(OP2, 3, VAL); \
70 READ_WB_REG_CASE(OP2, 4, VAL); \
71 READ_WB_REG_CASE(OP2, 5, VAL); \
72 READ_WB_REG_CASE(OP2, 6, VAL); \
73 READ_WB_REG_CASE(OP2, 7, VAL); \
74 READ_WB_REG_CASE(OP2, 8, VAL); \
75 READ_WB_REG_CASE(OP2, 9, VAL); \
76 READ_WB_REG_CASE(OP2, 10, VAL); \
77 READ_WB_REG_CASE(OP2, 11, VAL); \
78 READ_WB_REG_CASE(OP2, 12, VAL); \
79 READ_WB_REG_CASE(OP2, 13, VAL); \
80 READ_WB_REG_CASE(OP2, 14, VAL); \
81 READ_WB_REG_CASE(OP2, 15, VAL)
82
83#define GEN_WRITE_WB_REG_CASES(OP2, VAL) \
84 WRITE_WB_REG_CASE(OP2, 0, VAL); \
85 WRITE_WB_REG_CASE(OP2, 1, VAL); \
86 WRITE_WB_REG_CASE(OP2, 2, VAL); \
87 WRITE_WB_REG_CASE(OP2, 3, VAL); \
88 WRITE_WB_REG_CASE(OP2, 4, VAL); \
89 WRITE_WB_REG_CASE(OP2, 5, VAL); \
90 WRITE_WB_REG_CASE(OP2, 6, VAL); \
91 WRITE_WB_REG_CASE(OP2, 7, VAL); \
92 WRITE_WB_REG_CASE(OP2, 8, VAL); \
93 WRITE_WB_REG_CASE(OP2, 9, VAL); \
94 WRITE_WB_REG_CASE(OP2, 10, VAL); \
95 WRITE_WB_REG_CASE(OP2, 11, VAL); \
96 WRITE_WB_REG_CASE(OP2, 12, VAL); \
97 WRITE_WB_REG_CASE(OP2, 13, VAL); \
98 WRITE_WB_REG_CASE(OP2, 14, VAL); \
99 WRITE_WB_REG_CASE(OP2, 15, VAL)
100
101static u32 read_wb_reg(int n)
102{
103 u32 val = 0;
104
105 switch (n) {
106 GEN_READ_WB_REG_CASES(ARM_OP2_BVR, val);
107 GEN_READ_WB_REG_CASES(ARM_OP2_BCR, val);
108 GEN_READ_WB_REG_CASES(ARM_OP2_WVR, val);
109 GEN_READ_WB_REG_CASES(ARM_OP2_WCR, val);
110 default:
111 pr_warning("attempt to read from unknown breakpoint "
112 "register %d\n", n);
113 }
114
115 return val;
116}
117
118static void write_wb_reg(int n, u32 val)
119{
120 switch (n) {
121 GEN_WRITE_WB_REG_CASES(ARM_OP2_BVR, val);
122 GEN_WRITE_WB_REG_CASES(ARM_OP2_BCR, val);
123 GEN_WRITE_WB_REG_CASES(ARM_OP2_WVR, val);
124 GEN_WRITE_WB_REG_CASES(ARM_OP2_WCR, val);
125 default:
126 pr_warning("attempt to write to unknown breakpoint "
127 "register %d\n", n);
128 }
129 isb();
130}
131
132/* Determine debug architecture. */
133static u8 get_debug_arch(void)
134{
135 u32 didr;
136
137 /* Do we implement the extended CPUID interface? */
138 if (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
139 pr_warning("CPUID feature registers not supported. "
140 "Assuming v6 debug is present.\n");
141 return ARM_DEBUG_ARCH_V6;
142 }
143
144 ARM_DBG_READ(c0, 0, didr);
145 return (didr >> 16) & 0xf;
146}
147
148u8 arch_get_debug_arch(void)
149{
150 return debug_arch;
151}
152
153static int debug_arch_supported(void)
154{
155 u8 arch = get_debug_arch();
156
157 /* We don't support the memory-mapped interface. */
158 return (arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14) ||
159 arch >= ARM_DEBUG_ARCH_V7_1;
160}
161
162/* Can we determine the watchpoint access type from the fsr? */
163static int debug_exception_updates_fsr(void)
164{
165 return 0;
166}
167
168/* Determine number of WRP registers available. */
169static int get_num_wrp_resources(void)
170{
171 u32 didr;
172 ARM_DBG_READ(c0, 0, didr);
173 return ((didr >> 28) & 0xf) + 1;
174}
175
176/* Determine number of BRP registers available. */
177static int get_num_brp_resources(void)
178{
179 u32 didr;
180 ARM_DBG_READ(c0, 0, didr);
181 return ((didr >> 24) & 0xf) + 1;
182}
183
184/* Does this core support mismatch breakpoints? */
185static int core_has_mismatch_brps(void)
186{
187 return (get_debug_arch() >= ARM_DEBUG_ARCH_V7_ECP14 &&
188 get_num_brp_resources() > 1);
189}
190
191/* Determine number of usable WRPs available. */
192static int get_num_wrps(void)
193{
194 /*
195 * On debug architectures prior to 7.1, when a watchpoint fires, the
196 * only way to work out which watchpoint it was is by disassembling
197 * the faulting instruction and working out the address of the memory
198 * access.
199 *
200 * Furthermore, we can only do this if the watchpoint was precise
201 * since imprecise watchpoints prevent us from calculating register
202 * based addresses.
203 *
204 * Providing we have more than 1 breakpoint register, we only report
205 * a single watchpoint register for the time being. This way, we always
206 * know which watchpoint fired. In the future we can either add a
207 * disassembler and address generation emulator, or we can insert a
208 * check to see if the DFAR is set on watchpoint exception entry
209 * [the ARM ARM states that the DFAR is UNKNOWN, but experience shows
210 * that it is set on some implementations].
211 */
212 if (get_debug_arch() < ARM_DEBUG_ARCH_V7_1)
213 return 1;
214
215 return get_num_wrp_resources();
216}
217
218/* Determine number of usable BRPs available. */
219static int get_num_brps(void)
220{
221 int brps = get_num_brp_resources();
222 return core_has_mismatch_brps() ? brps - 1 : brps;
223}
224
225/*
226 * In order to access the breakpoint/watchpoint control registers,
227 * we must be running in debug monitor mode. Unfortunately, we can
228 * be put into halting debug mode at any time by an external debugger
229 * but there is nothing we can do to prevent that.
230 */
231static int enable_monitor_mode(void)
232{
233 u32 dscr;
234 int ret = 0;
235
236 ARM_DBG_READ(c1, 0, dscr);
237
238 /* Ensure that halting mode is disabled. */
239 if (WARN_ONCE(dscr & ARM_DSCR_HDBGEN,
240 "halting debug mode enabled. Unable to access hardware resources.\n")) {
241 ret = -EPERM;
242 goto out;
243 }
244
245 /* If monitor mode is already enabled, just return. */
246 if (dscr & ARM_DSCR_MDBGEN)
247 goto out;
248
249 /* Write to the corresponding DSCR. */
250 switch (get_debug_arch()) {
251 case ARM_DEBUG_ARCH_V6:
252 case ARM_DEBUG_ARCH_V6_1:
253 ARM_DBG_WRITE(c1, 0, (dscr | ARM_DSCR_MDBGEN));
254 break;
255 case ARM_DEBUG_ARCH_V7_ECP14:
256 case ARM_DEBUG_ARCH_V7_1:
257 ARM_DBG_WRITE(c2, 2, (dscr | ARM_DSCR_MDBGEN));
258 break;
259 default:
260 ret = -ENODEV;
261 goto out;
262 }
263
264 /* Check that the write made it through. */
265 ARM_DBG_READ(c1, 0, dscr);
266 if (!(dscr & ARM_DSCR_MDBGEN))
267 ret = -EPERM;
268
269out:
270 return ret;
271}
272
273int hw_breakpoint_slots(int type)
274{
275 if (!debug_arch_supported())
276 return 0;
277
278 /*
279 * We can be called early, so don't rely on
280 * our static variables being initialised.
281 */
282 switch (type) {
283 case TYPE_INST:
284 return get_num_brps();
285 case TYPE_DATA:
286 return get_num_wrps();
287 default:
288 pr_warning("unknown slot type: %d\n", type);
289 return 0;
290 }
291}
292
293/*
294 * Check if 8-bit byte-address select is available.
295 * This clobbers WRP 0.
296 */
297static u8 get_max_wp_len(void)
298{
299 u32 ctrl_reg;
300 struct arch_hw_breakpoint_ctrl ctrl;
301 u8 size = 4;
302
303 if (debug_arch < ARM_DEBUG_ARCH_V7_ECP14)
304 goto out;
305
306 memset(&ctrl, 0, sizeof(ctrl));
307 ctrl.len = ARM_BREAKPOINT_LEN_8;
308 ctrl_reg = encode_ctrl_reg(ctrl);
309
310 write_wb_reg(ARM_BASE_WVR, 0);
311 write_wb_reg(ARM_BASE_WCR, ctrl_reg);
312 if ((read_wb_reg(ARM_BASE_WCR) & ctrl_reg) == ctrl_reg)
313 size = 8;
314
315out:
316 return size;
317}
318
319u8 arch_get_max_wp_len(void)
320{
321 return max_watchpoint_len;
322}
323
324/*
325 * Install a perf counter breakpoint.
326 */
327int arch_install_hw_breakpoint(struct perf_event *bp)
328{
329 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
330 struct perf_event **slot, **slots;
331 int i, max_slots, ctrl_base, val_base, ret = 0;
332 u32 addr, ctrl;
333
334 /* Ensure that we are in monitor mode and halting mode is disabled. */
335 ret = enable_monitor_mode();
336 if (ret)
337 goto out;
338
339 addr = info->address;
340 ctrl = encode_ctrl_reg(info->ctrl) | 0x1;
341
342 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
343 /* Breakpoint */
344 ctrl_base = ARM_BASE_BCR;
345 val_base = ARM_BASE_BVR;
346 slots = (struct perf_event **)__get_cpu_var(bp_on_reg);
347 max_slots = core_num_brps;
348 } else {
349 /* Watchpoint */
350 ctrl_base = ARM_BASE_WCR;
351 val_base = ARM_BASE_WVR;
352 slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
353 max_slots = core_num_wrps;
354 }
355
356 for (i = 0; i < max_slots; ++i) {
357 slot = &slots[i];
358
359 if (!*slot) {
360 *slot = bp;
361 break;
362 }
363 }
364
365 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot\n")) {
366 ret = -EBUSY;
367 goto out;
368 }
369
370 /* Override the breakpoint data with the step data. */
371 if (info->step_ctrl.enabled) {
372 addr = info->trigger & ~0x3;
373 ctrl = encode_ctrl_reg(info->step_ctrl);
374 if (info->ctrl.type != ARM_BREAKPOINT_EXECUTE) {
375 i = 0;
376 ctrl_base = ARM_BASE_BCR + core_num_brps;
377 val_base = ARM_BASE_BVR + core_num_brps;
378 }
379 }
380
381 /* Setup the address register. */
382 write_wb_reg(val_base + i, addr);
383
384 /* Setup the control register. */
385 write_wb_reg(ctrl_base + i, ctrl);
386
387out:
388 return ret;
389}
390
391void arch_uninstall_hw_breakpoint(struct perf_event *bp)
392{
393 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
394 struct perf_event **slot, **slots;
395 int i, max_slots, base;
396
397 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
398 /* Breakpoint */
399 base = ARM_BASE_BCR;
400 slots = (struct perf_event **)__get_cpu_var(bp_on_reg);
401 max_slots = core_num_brps;
402 } else {
403 /* Watchpoint */
404 base = ARM_BASE_WCR;
405 slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
406 max_slots = core_num_wrps;
407 }
408
409 /* Remove the breakpoint. */
410 for (i = 0; i < max_slots; ++i) {
411 slot = &slots[i];
412
413 if (*slot == bp) {
414 *slot = NULL;
415 break;
416 }
417 }
418
419 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot\n"))
420 return;
421
422 /* Ensure that we disable the mismatch breakpoint. */
423 if (info->ctrl.type != ARM_BREAKPOINT_EXECUTE &&
424 info->step_ctrl.enabled) {
425 i = 0;
426 base = ARM_BASE_BCR + core_num_brps;
427 }
428
429 /* Reset the control register. */
430 write_wb_reg(base + i, 0);
431}
432
433static int get_hbp_len(u8 hbp_len)
434{
435 unsigned int len_in_bytes = 0;
436
437 switch (hbp_len) {
438 case ARM_BREAKPOINT_LEN_1:
439 len_in_bytes = 1;
440 break;
441 case ARM_BREAKPOINT_LEN_2:
442 len_in_bytes = 2;
443 break;
444 case ARM_BREAKPOINT_LEN_4:
445 len_in_bytes = 4;
446 break;
447 case ARM_BREAKPOINT_LEN_8:
448 len_in_bytes = 8;
449 break;
450 }
451
452 return len_in_bytes;
453}
454
455/*
456 * Check whether bp virtual address is in kernel space.
457 */
458int arch_check_bp_in_kernelspace(struct perf_event *bp)
459{
460 unsigned int len;
461 unsigned long va;
462 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
463
464 va = info->address;
465 len = get_hbp_len(info->ctrl.len);
466
467 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
468}
469
470/*
471 * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
472 * Hopefully this will disappear when ptrace can bypass the conversion
473 * to generic breakpoint descriptions.
474 */
475int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
476 int *gen_len, int *gen_type)
477{
478 /* Type */
479 switch (ctrl.type) {
480 case ARM_BREAKPOINT_EXECUTE:
481 *gen_type = HW_BREAKPOINT_X;
482 break;
483 case ARM_BREAKPOINT_LOAD:
484 *gen_type = HW_BREAKPOINT_R;
485 break;
486 case ARM_BREAKPOINT_STORE:
487 *gen_type = HW_BREAKPOINT_W;
488 break;
489 case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE:
490 *gen_type = HW_BREAKPOINT_RW;
491 break;
492 default:
493 return -EINVAL;
494 }
495
496 /* Len */
497 switch (ctrl.len) {
498 case ARM_BREAKPOINT_LEN_1:
499 *gen_len = HW_BREAKPOINT_LEN_1;
500 break;
501 case ARM_BREAKPOINT_LEN_2:
502 *gen_len = HW_BREAKPOINT_LEN_2;
503 break;
504 case ARM_BREAKPOINT_LEN_4:
505 *gen_len = HW_BREAKPOINT_LEN_4;
506 break;
507 case ARM_BREAKPOINT_LEN_8:
508 *gen_len = HW_BREAKPOINT_LEN_8;
509 break;
510 default:
511 return -EINVAL;
512 }
513
514 return 0;
515}
516
517/*
518 * Construct an arch_hw_breakpoint from a perf_event.
519 */
520static int arch_build_bp_info(struct perf_event *bp)
521{
522 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
523
524 /* Type */
525 switch (bp->attr.bp_type) {
526 case HW_BREAKPOINT_X:
527 info->ctrl.type = ARM_BREAKPOINT_EXECUTE;
528 break;
529 case HW_BREAKPOINT_R:
530 info->ctrl.type = ARM_BREAKPOINT_LOAD;
531 break;
532 case HW_BREAKPOINT_W:
533 info->ctrl.type = ARM_BREAKPOINT_STORE;
534 break;
535 case HW_BREAKPOINT_RW:
536 info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
537 break;
538 default:
539 return -EINVAL;
540 }
541
542 /* Len */
543 switch (bp->attr.bp_len) {
544 case HW_BREAKPOINT_LEN_1:
545 info->ctrl.len = ARM_BREAKPOINT_LEN_1;
546 break;
547 case HW_BREAKPOINT_LEN_2:
548 info->ctrl.len = ARM_BREAKPOINT_LEN_2;
549 break;
550 case HW_BREAKPOINT_LEN_4:
551 info->ctrl.len = ARM_BREAKPOINT_LEN_4;
552 break;
553 case HW_BREAKPOINT_LEN_8:
554 info->ctrl.len = ARM_BREAKPOINT_LEN_8;
555 if ((info->ctrl.type != ARM_BREAKPOINT_EXECUTE)
556 && max_watchpoint_len >= 8)
557 break;
558 default:
559 return -EINVAL;
560 }
561
562 /*
563 * Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes.
564 * Watchpoints can be of length 1, 2, 4 or 8 bytes if supported
565 * by the hardware and must be aligned to the appropriate number of
566 * bytes.
567 */
568 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE &&
569 info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
570 info->ctrl.len != ARM_BREAKPOINT_LEN_4)
571 return -EINVAL;
572
573 /* Address */
574 info->address = bp->attr.bp_addr;
575
576 /* Privilege */
577 info->ctrl.privilege = ARM_BREAKPOINT_USER;
578 if (arch_check_bp_in_kernelspace(bp))
579 info->ctrl.privilege |= ARM_BREAKPOINT_PRIV;
580
581 /* Enabled? */
582 info->ctrl.enabled = !bp->attr.disabled;
583
584 /* Mismatch */
585 info->ctrl.mismatch = 0;
586
587 return 0;
588}
589
590/*
591 * Validate the arch-specific HW Breakpoint register settings.
592 */
593int arch_validate_hwbkpt_settings(struct perf_event *bp)
594{
595 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
596 int ret = 0;
597 u32 offset, alignment_mask = 0x3;
598
599 /* Build the arch_hw_breakpoint. */
600 ret = arch_build_bp_info(bp);
601 if (ret)
602 goto out;
603
604 /* Check address alignment. */
605 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
606 alignment_mask = 0x7;
607 offset = info->address & alignment_mask;
608 switch (offset) {
609 case 0:
610 /* Aligned */
611 break;
612 case 1:
613 /* Allow single byte watchpoint. */
614 if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
615 break;
616 case 2:
617 /* Allow halfword watchpoints and breakpoints. */
618 if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
619 break;
620 default:
621 ret = -EINVAL;
622 goto out;
623 }
624
625 info->address &= ~alignment_mask;
626 info->ctrl.len <<= offset;
627
628 if (!bp->overflow_handler) {
629 /*
630 * Mismatch breakpoints are required for single-stepping
631 * breakpoints.
632 */
633 if (!core_has_mismatch_brps())
634 return -EINVAL;
635
636 /* We don't allow mismatch breakpoints in kernel space. */
637 if (arch_check_bp_in_kernelspace(bp))
638 return -EPERM;
639
640 /*
641 * Per-cpu breakpoints are not supported by our stepping
642 * mechanism.
643 */
644 if (!bp->hw.bp_target)
645 return -EINVAL;
646
647 /*
648 * We only support specific access types if the fsr
649 * reports them.
650 */
651 if (!debug_exception_updates_fsr() &&
652 (info->ctrl.type == ARM_BREAKPOINT_LOAD ||
653 info->ctrl.type == ARM_BREAKPOINT_STORE))
654 return -EINVAL;
655 }
656
657out:
658 return ret;
659}
660
661/*
662 * Enable/disable single-stepping over the breakpoint bp at address addr.
663 */
664static void enable_single_step(struct perf_event *bp, u32 addr)
665{
666 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
667
668 arch_uninstall_hw_breakpoint(bp);
669 info->step_ctrl.mismatch = 1;
670 info->step_ctrl.len = ARM_BREAKPOINT_LEN_4;
671 info->step_ctrl.type = ARM_BREAKPOINT_EXECUTE;
672 info->step_ctrl.privilege = info->ctrl.privilege;
673 info->step_ctrl.enabled = 1;
674 info->trigger = addr;
675 arch_install_hw_breakpoint(bp);
676}
677
678static void disable_single_step(struct perf_event *bp)
679{
680 arch_uninstall_hw_breakpoint(bp);
681 counter_arch_bp(bp)->step_ctrl.enabled = 0;
682 arch_install_hw_breakpoint(bp);
683}
684
685static void watchpoint_handler(unsigned long addr, unsigned int fsr,
686 struct pt_regs *regs)
687{
688 int i, access;
689 u32 val, ctrl_reg, alignment_mask;
690 struct perf_event *wp, **slots;
691 struct arch_hw_breakpoint *info;
692 struct arch_hw_breakpoint_ctrl ctrl;
693
694 slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
695
696 for (i = 0; i < core_num_wrps; ++i) {
697 rcu_read_lock();
698
699 wp = slots[i];
700
701 if (wp == NULL)
702 goto unlock;
703
704 info = counter_arch_bp(wp);
705 /*
706 * The DFAR is an unknown value on debug architectures prior
707 * to 7.1. Since we only allow a single watchpoint on these
708 * older CPUs, we can set the trigger to the lowest possible
709 * faulting address.
710 */
711 if (debug_arch < ARM_DEBUG_ARCH_V7_1) {
712 BUG_ON(i > 0);
713 info->trigger = wp->attr.bp_addr;
714 } else {
715 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
716 alignment_mask = 0x7;
717 else
718 alignment_mask = 0x3;
719
720 /* Check if the watchpoint value matches. */
721 val = read_wb_reg(ARM_BASE_WVR + i);
722 if (val != (addr & ~alignment_mask))
723 goto unlock;
724
725 /* Possible match, check the byte address select. */
726 ctrl_reg = read_wb_reg(ARM_BASE_WCR + i);
727 decode_ctrl_reg(ctrl_reg, &ctrl);
728 if (!((1 << (addr & alignment_mask)) & ctrl.len))
729 goto unlock;
730
731 /* Check that the access type matches. */
732 if (debug_exception_updates_fsr()) {
733 access = (fsr & ARM_FSR_ACCESS_MASK) ?
734 HW_BREAKPOINT_W : HW_BREAKPOINT_R;
735 if (!(access & hw_breakpoint_type(wp)))
736 goto unlock;
737 }
738
739 /* We have a winner. */
740 info->trigger = addr;
741 }
742
743 pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
744 perf_bp_event(wp, regs);
745
746 /*
747 * If no overflow handler is present, insert a temporary
748 * mismatch breakpoint so we can single-step over the
749 * watchpoint trigger.
750 */
751 if (!wp->overflow_handler)
752 enable_single_step(wp, instruction_pointer(regs));
753
754unlock:
755 rcu_read_unlock();
756 }
757}
758
759static void watchpoint_single_step_handler(unsigned long pc)
760{
761 int i;
762 struct perf_event *wp, **slots;
763 struct arch_hw_breakpoint *info;
764
765 slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
766
767 for (i = 0; i < core_num_wrps; ++i) {
768 rcu_read_lock();
769
770 wp = slots[i];
771
772 if (wp == NULL)
773 goto unlock;
774
775 info = counter_arch_bp(wp);
776 if (!info->step_ctrl.enabled)
777 goto unlock;
778
779 /*
780 * Restore the original watchpoint if we've completed the
781 * single-step.
782 */
783 if (info->trigger != pc)
784 disable_single_step(wp);
785
786unlock:
787 rcu_read_unlock();
788 }
789}
790
791static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
792{
793 int i;
794 u32 ctrl_reg, val, addr;
795 struct perf_event *bp, **slots;
796 struct arch_hw_breakpoint *info;
797 struct arch_hw_breakpoint_ctrl ctrl;
798
799 slots = (struct perf_event **)__get_cpu_var(bp_on_reg);
800
801 /* The exception entry code places the amended lr in the PC. */
802 addr = regs->ARM_pc;
803
804 /* Check the currently installed breakpoints first. */
805 for (i = 0; i < core_num_brps; ++i) {
806 rcu_read_lock();
807
808 bp = slots[i];
809
810 if (bp == NULL)
811 goto unlock;
812
813 info = counter_arch_bp(bp);
814
815 /* Check if the breakpoint value matches. */
816 val = read_wb_reg(ARM_BASE_BVR + i);
817 if (val != (addr & ~0x3))
818 goto mismatch;
819
820 /* Possible match, check the byte address select to confirm. */
821 ctrl_reg = read_wb_reg(ARM_BASE_BCR + i);
822 decode_ctrl_reg(ctrl_reg, &ctrl);
823 if ((1 << (addr & 0x3)) & ctrl.len) {
824 info->trigger = addr;
825 pr_debug("breakpoint fired: address = 0x%x\n", addr);
826 perf_bp_event(bp, regs);
827 if (!bp->overflow_handler)
828 enable_single_step(bp, addr);
829 goto unlock;
830 }
831
832mismatch:
833 /* If we're stepping a breakpoint, it can now be restored. */
834 if (info->step_ctrl.enabled)
835 disable_single_step(bp);
836unlock:
837 rcu_read_unlock();
838 }
839
840 /* Handle any pending watchpoint single-step breakpoints. */
841 watchpoint_single_step_handler(addr);
842}
843
844/*
845 * Called from either the Data Abort Handler [watchpoint] or the
846 * Prefetch Abort Handler [breakpoint] with interrupts disabled.
847 */
848static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
849 struct pt_regs *regs)
850{
851 int ret = 0;
852 u32 dscr;
853
854 preempt_disable();
855
856 if (interrupts_enabled(regs))
857 local_irq_enable();
858
859 /* We only handle watchpoints and hardware breakpoints. */
860 ARM_DBG_READ(c1, 0, dscr);
861
862 /* Perform perf callbacks. */
863 switch (ARM_DSCR_MOE(dscr)) {
864 case ARM_ENTRY_BREAKPOINT:
865 breakpoint_handler(addr, regs);
866 break;
867 case ARM_ENTRY_ASYNC_WATCHPOINT:
868 WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
869 case ARM_ENTRY_SYNC_WATCHPOINT:
870 watchpoint_handler(addr, fsr, regs);
871 break;
872 default:
873 ret = 1; /* Unhandled fault. */
874 }
875
876 preempt_enable();
877
878 return ret;
879}
880
881/*
882 * One-time initialisation.
883 */
884static cpumask_t debug_err_mask;
885
886static int debug_reg_trap(struct pt_regs *regs, unsigned int instr)
887{
888 int cpu = smp_processor_id();
889
890 pr_warning("Debug register access (0x%x) caused undefined instruction on CPU %d\n",
891 instr, cpu);
892
893 /* Set the error flag for this CPU and skip the faulting instruction. */
894 cpumask_set_cpu(cpu, &debug_err_mask);
895 instruction_pointer(regs) += 4;
896 return 0;
897}
898
899static struct undef_hook debug_reg_hook = {
900 .instr_mask = 0x0fe80f10,
901 .instr_val = 0x0e000e10,
902 .fn = debug_reg_trap,
903};
904
905static void reset_ctrl_regs(void *unused)
906{
907 int i, raw_num_brps, err = 0, cpu = smp_processor_id();
908 u32 dbg_power;
909
910 /*
911 * v7 debug contains save and restore registers so that debug state
912 * can be maintained across low-power modes without leaving the debug
913 * logic powered up. It is IMPLEMENTATION DEFINED whether we can access
914 * the debug registers out of reset, so we must unlock the OS Lock
915 * Access Register to avoid taking undefined instruction exceptions
916 * later on.
917 */
918 switch (debug_arch) {
919 case ARM_DEBUG_ARCH_V6:
920 case ARM_DEBUG_ARCH_V6_1:
921 /* ARMv6 cores just need to reset the registers. */
922 goto reset_regs;
923 case ARM_DEBUG_ARCH_V7_ECP14:
924 /*
925 * Ensure sticky power-down is clear (i.e. debug logic is
926 * powered up).
927 */
928 asm volatile("mrc p14, 0, %0, c1, c5, 4" : "=r" (dbg_power));
929 if ((dbg_power & 0x1) == 0)
930 err = -EPERM;
931 break;
932 case ARM_DEBUG_ARCH_V7_1:
933 /*
934 * Ensure the OS double lock is clear.
935 */
936 asm volatile("mrc p14, 0, %0, c1, c3, 4" : "=r" (dbg_power));
937 if ((dbg_power & 0x1) == 1)
938 err = -EPERM;
939 break;
940 }
941
942 if (err) {
943 pr_warning("CPU %d debug is powered down!\n", cpu);
944 cpumask_or(&debug_err_mask, &debug_err_mask, cpumask_of(cpu));
945 return;
946 }
947
948 /*
949 * Unconditionally clear the lock by writing a value
950 * other than 0xC5ACCE55 to the access register.
951 */
952 asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
953 isb();
954
955 /*
956 * Clear any configured vector-catch events before
957 * enabling monitor mode.
958 */
959 asm volatile("mcr p14, 0, %0, c0, c7, 0" : : "r" (0));
960 isb();
961
962reset_regs:
963 if (enable_monitor_mode())
964 return;
965
966 /* We must also reset any reserved registers. */
967 raw_num_brps = get_num_brp_resources();
968 for (i = 0; i < raw_num_brps; ++i) {
969 write_wb_reg(ARM_BASE_BCR + i, 0UL);
970 write_wb_reg(ARM_BASE_BVR + i, 0UL);
971 }
972
973 for (i = 0; i < core_num_wrps; ++i) {
974 write_wb_reg(ARM_BASE_WCR + i, 0UL);
975 write_wb_reg(ARM_BASE_WVR + i, 0UL);
976 }
977}
978
979static int __cpuinit dbg_reset_notify(struct notifier_block *self,
980 unsigned long action, void *cpu)
981{
982 if (action == CPU_ONLINE)
983 smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
984
985 return NOTIFY_OK;
986}
987
988static struct notifier_block __cpuinitdata dbg_reset_nb = {
989 .notifier_call = dbg_reset_notify,
990};
991
992static int __init arch_hw_breakpoint_init(void)
993{
994 u32 dscr;
995
996 debug_arch = get_debug_arch();
997
998 if (!debug_arch_supported()) {
999 pr_info("debug architecture 0x%x unsupported.\n", debug_arch);
1000 return 0;
1001 }
1002
1003 /* Determine how many BRPs/WRPs are available. */
1004 core_num_brps = get_num_brps();
1005 core_num_wrps = get_num_wrps();
1006
1007 /*
1008 * We need to tread carefully here because DBGSWENABLE may be
1009 * driven low on this core and there isn't an architected way to
1010 * determine that.
1011 */
1012 register_undef_hook(&debug_reg_hook);
1013
1014 /*
1015 * Reset the breakpoint resources. We assume that a halting
1016 * debugger will leave the world in a nice state for us.
1017 */
1018 on_each_cpu(reset_ctrl_regs, NULL, 1);
1019 unregister_undef_hook(&debug_reg_hook);
1020 if (!cpumask_empty(&debug_err_mask)) {
1021 core_num_brps = 0;
1022 core_num_wrps = 0;
1023 return 0;
1024 }
1025
1026 pr_info("found %d " "%s" "breakpoint and %d watchpoint registers.\n",
1027 core_num_brps, core_has_mismatch_brps() ? "(+1 reserved) " :
1028 "", core_num_wrps);
1029
1030 ARM_DBG_READ(c1, 0, dscr);
1031 if (dscr & ARM_DSCR_HDBGEN) {
1032 max_watchpoint_len = 4;
1033 pr_warning("halting debug mode enabled. Assuming maximum watchpoint size of %u bytes.\n",
1034 max_watchpoint_len);
1035 } else {
1036 /* Work out the maximum supported watchpoint length. */
1037 max_watchpoint_len = get_max_wp_len();
1038 pr_info("maximum watchpoint size is %u bytes.\n",
1039 max_watchpoint_len);
1040 }
1041
1042 /* Register debug fault handler. */
1043 hook_fault_code(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,
1044 TRAP_HWBKPT, "watchpoint debug exception");
1045 hook_ifault_code(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,
1046 TRAP_HWBKPT, "breakpoint debug exception");
1047
1048 /* Register hotplug notifier. */
1049 register_cpu_notifier(&dbg_reset_nb);
1050 return 0;
1051}
1052arch_initcall(arch_hw_breakpoint_init);
1053
1054void hw_breakpoint_pmu_read(struct perf_event *bp)
1055{
1056}
1057
1058/*
1059 * Dummy function to register with die_notifier.
1060 */
1061int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
1062 unsigned long val, void *data)
1063{
1064 return NOTIFY_DONE;
1065}