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.
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.
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.
15 * Copyright (C) 2009, 2010 ARM Limited
17 * Author: Will Deacon <will.deacon@arm.com>
21 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
22 * using the CPU's debug registers.
24 #define pr_fmt(fmt) "hw-breakpoint: " fmt
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>
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/system.h>
38 #include <asm/traps.h>
40 /* Breakpoint currently in use for each BRP. */
41 static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
43 /* Watchpoint currently in use for each WRP. */
44 static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]);
46 /* Number of BRP/WRP registers on this CPU. */
47 static int core_num_brps;
48 static int core_num_reserved_brps;
49 static int core_num_wrps;
51 /* Debug architecture version. */
54 /* Maximum supported watchpoint length. */
55 static u8 max_watchpoint_len;
57 #define READ_WB_REG_CASE(OP2, M, VAL) \
58 case ((OP2 << 4) + M): \
59 ARM_DBG_READ(c ## M, OP2, VAL); \
62 #define WRITE_WB_REG_CASE(OP2, M, VAL) \
63 case ((OP2 << 4) + M): \
64 ARM_DBG_WRITE(c ## M, OP2, VAL);\
67 #define GEN_READ_WB_REG_CASES(OP2, VAL) \
68 READ_WB_REG_CASE(OP2, 0, VAL); \
69 READ_WB_REG_CASE(OP2, 1, VAL); \
70 READ_WB_REG_CASE(OP2, 2, VAL); \
71 READ_WB_REG_CASE(OP2, 3, VAL); \
72 READ_WB_REG_CASE(OP2, 4, VAL); \
73 READ_WB_REG_CASE(OP2, 5, VAL); \
74 READ_WB_REG_CASE(OP2, 6, VAL); \
75 READ_WB_REG_CASE(OP2, 7, VAL); \
76 READ_WB_REG_CASE(OP2, 8, VAL); \
77 READ_WB_REG_CASE(OP2, 9, VAL); \
78 READ_WB_REG_CASE(OP2, 10, VAL); \
79 READ_WB_REG_CASE(OP2, 11, VAL); \
80 READ_WB_REG_CASE(OP2, 12, VAL); \
81 READ_WB_REG_CASE(OP2, 13, VAL); \
82 READ_WB_REG_CASE(OP2, 14, VAL); \
83 READ_WB_REG_CASE(OP2, 15, VAL)
85 #define GEN_WRITE_WB_REG_CASES(OP2, VAL) \
86 WRITE_WB_REG_CASE(OP2, 0, VAL); \
87 WRITE_WB_REG_CASE(OP2, 1, VAL); \
88 WRITE_WB_REG_CASE(OP2, 2, VAL); \
89 WRITE_WB_REG_CASE(OP2, 3, VAL); \
90 WRITE_WB_REG_CASE(OP2, 4, VAL); \
91 WRITE_WB_REG_CASE(OP2, 5, VAL); \
92 WRITE_WB_REG_CASE(OP2, 6, VAL); \
93 WRITE_WB_REG_CASE(OP2, 7, VAL); \
94 WRITE_WB_REG_CASE(OP2, 8, VAL); \
95 WRITE_WB_REG_CASE(OP2, 9, VAL); \
96 WRITE_WB_REG_CASE(OP2, 10, VAL); \
97 WRITE_WB_REG_CASE(OP2, 11, VAL); \
98 WRITE_WB_REG_CASE(OP2, 12, VAL); \
99 WRITE_WB_REG_CASE(OP2, 13, VAL); \
100 WRITE_WB_REG_CASE(OP2, 14, VAL); \
101 WRITE_WB_REG_CASE(OP2, 15, VAL)
103 static u32 read_wb_reg(int n)
108 GEN_READ_WB_REG_CASES(ARM_OP2_BVR, val);
109 GEN_READ_WB_REG_CASES(ARM_OP2_BCR, val);
110 GEN_READ_WB_REG_CASES(ARM_OP2_WVR, val);
111 GEN_READ_WB_REG_CASES(ARM_OP2_WCR, val);
113 pr_warning("attempt to read from unknown breakpoint "
120 static void write_wb_reg(int n, u32 val)
123 GEN_WRITE_WB_REG_CASES(ARM_OP2_BVR, val);
124 GEN_WRITE_WB_REG_CASES(ARM_OP2_BCR, val);
125 GEN_WRITE_WB_REG_CASES(ARM_OP2_WVR, val);
126 GEN_WRITE_WB_REG_CASES(ARM_OP2_WCR, val);
128 pr_warning("attempt to write to unknown breakpoint "
134 /* Determine debug architecture. */
135 static u8 get_debug_arch(void)
139 /* Do we implement the extended CPUID interface? */
140 if (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
141 pr_warning("CPUID feature registers not supported. "
142 "Assuming v6 debug is present.\n");
143 return ARM_DEBUG_ARCH_V6;
146 ARM_DBG_READ(c0, 0, didr);
147 return (didr >> 16) & 0xf;
150 u8 arch_get_debug_arch(void)
155 /* Determine number of BRP register available. */
156 static int get_num_brp_resources(void)
159 ARM_DBG_READ(c0, 0, didr);
160 return ((didr >> 24) & 0xf) + 1;
163 /* Does this core support mismatch breakpoints? */
164 static int core_has_mismatch_brps(void)
166 return (get_debug_arch() >= ARM_DEBUG_ARCH_V7_ECP14 &&
167 get_num_brp_resources() > 1);
170 /* Determine number of usable WRPs available. */
171 static int get_num_wrps(void)
174 * FIXME: When a watchpoint fires, the only way to work out which
175 * watchpoint it was is by disassembling the faulting instruction
176 * and working out the address of the memory access.
178 * Furthermore, we can only do this if the watchpoint was precise
179 * since imprecise watchpoints prevent us from calculating register
182 * Providing we have more than 1 breakpoint register, we only report
183 * a single watchpoint register for the time being. This way, we always
184 * know which watchpoint fired. In the future we can either add a
185 * disassembler and address generation emulator, or we can insert a
186 * check to see if the DFAR is set on watchpoint exception entry
187 * [the ARM ARM states that the DFAR is UNKNOWN, but experience shows
188 * that it is set on some implementations].
194 ARM_DBG_READ(c0, 0, didr);
195 wrps = ((didr >> 28) & 0xf) + 1;
199 if (core_has_mismatch_brps() && wrps >= get_num_brp_resources())
200 wrps = get_num_brp_resources() - 1;
205 /* We reserve one breakpoint for each watchpoint. */
206 static int get_num_reserved_brps(void)
208 if (core_has_mismatch_brps())
209 return get_num_wrps();
213 /* Determine number of usable BRPs available. */
214 static int get_num_brps(void)
216 int brps = get_num_brp_resources();
217 if (core_has_mismatch_brps())
218 brps -= get_num_reserved_brps();
222 int hw_breakpoint_slots(int type)
225 * We can be called early, so don't rely on
226 * our static variables being initialised.
230 return get_num_brps();
232 return get_num_wrps();
234 pr_warning("unknown slot type: %d\n", type);
240 * In order to access the breakpoint/watchpoint control registers,
241 * we must be running in debug monitor mode. Unfortunately, we can
242 * be put into halting debug mode at any time by an external debugger
243 * but there is nothing we can do to prevent that.
245 static int enable_monitor_mode(void)
250 ARM_DBG_READ(c1, 0, dscr);
252 /* Ensure that halting mode is disabled. */
253 if (WARN_ONCE(dscr & ARM_DSCR_HDBGEN, "halting debug mode enabled."
254 "Unable to access hardware resources.")) {
259 /* Write to the corresponding DSCR. */
260 switch (debug_arch) {
261 case ARM_DEBUG_ARCH_V6:
262 case ARM_DEBUG_ARCH_V6_1:
263 ARM_DBG_WRITE(c1, 0, (dscr | ARM_DSCR_MDBGEN));
265 case ARM_DEBUG_ARCH_V7_ECP14:
266 ARM_DBG_WRITE(c2, 2, (dscr | ARM_DSCR_MDBGEN));
273 /* Check that the write made it through. */
274 ARM_DBG_READ(c1, 0, dscr);
275 if (WARN_ONCE(!(dscr & ARM_DSCR_MDBGEN),
276 "failed to enable monitor mode.")) {
285 * Check if 8-bit byte-address select is available.
286 * This clobbers WRP 0.
288 static u8 get_max_wp_len(void)
291 struct arch_hw_breakpoint_ctrl ctrl;
294 if (debug_arch < ARM_DEBUG_ARCH_V7_ECP14)
297 if (enable_monitor_mode())
300 memset(&ctrl, 0, sizeof(ctrl));
301 ctrl.len = ARM_BREAKPOINT_LEN_8;
302 ctrl_reg = encode_ctrl_reg(ctrl);
304 write_wb_reg(ARM_BASE_WVR, 0);
305 write_wb_reg(ARM_BASE_WCR, ctrl_reg);
306 if ((read_wb_reg(ARM_BASE_WCR) & ctrl_reg) == ctrl_reg)
313 u8 arch_get_max_wp_len(void)
315 return max_watchpoint_len;
319 * Install a perf counter breakpoint.
321 int arch_install_hw_breakpoint(struct perf_event *bp)
323 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
324 struct perf_event **slot, **slots;
325 int i, max_slots, ctrl_base, val_base, ret = 0;
328 /* Ensure that we are in monitor mode and halting mode is disabled. */
329 ret = enable_monitor_mode();
333 addr = info->address;
334 ctrl = encode_ctrl_reg(info->ctrl) | 0x1;
336 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
338 ctrl_base = ARM_BASE_BCR;
339 val_base = ARM_BASE_BVR;
340 slots = __get_cpu_var(bp_on_reg);
341 max_slots = core_num_brps;
344 if (info->step_ctrl.enabled) {
345 /* Install into the reserved breakpoint region. */
346 ctrl_base = ARM_BASE_BCR + core_num_brps;
347 val_base = ARM_BASE_BVR + core_num_brps;
348 /* Override the watchpoint data with the step data. */
349 addr = info->trigger & ~0x3;
350 ctrl = encode_ctrl_reg(info->step_ctrl);
352 ctrl_base = ARM_BASE_WCR;
353 val_base = ARM_BASE_WVR;
355 slots = __get_cpu_var(wp_on_reg);
356 max_slots = core_num_wrps;
359 for (i = 0; i < max_slots; ++i) {
368 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot")) {
373 /* Setup the address register. */
374 write_wb_reg(val_base + i, addr);
376 /* Setup the control register. */
377 write_wb_reg(ctrl_base + i, ctrl);
383 void arch_uninstall_hw_breakpoint(struct perf_event *bp)
385 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
386 struct perf_event **slot, **slots;
387 int i, max_slots, base;
389 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
392 slots = __get_cpu_var(bp_on_reg);
393 max_slots = core_num_brps;
396 if (info->step_ctrl.enabled)
397 base = ARM_BASE_BCR + core_num_brps;
400 slots = __get_cpu_var(wp_on_reg);
401 max_slots = core_num_wrps;
404 /* Remove the breakpoint. */
405 for (i = 0; i < max_slots; ++i) {
414 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot"))
417 /* Reset the control register. */
418 write_wb_reg(base + i, 0);
421 static int get_hbp_len(u8 hbp_len)
423 unsigned int len_in_bytes = 0;
426 case ARM_BREAKPOINT_LEN_1:
429 case ARM_BREAKPOINT_LEN_2:
432 case ARM_BREAKPOINT_LEN_4:
435 case ARM_BREAKPOINT_LEN_8:
444 * Check whether bp virtual address is in kernel space.
446 int arch_check_bp_in_kernelspace(struct perf_event *bp)
450 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
453 len = get_hbp_len(info->ctrl.len);
455 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
459 * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
460 * Hopefully this will disappear when ptrace can bypass the conversion
461 * to generic breakpoint descriptions.
463 int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
464 int *gen_len, int *gen_type)
468 case ARM_BREAKPOINT_EXECUTE:
469 *gen_type = HW_BREAKPOINT_X;
471 case ARM_BREAKPOINT_LOAD:
472 *gen_type = HW_BREAKPOINT_R;
474 case ARM_BREAKPOINT_STORE:
475 *gen_type = HW_BREAKPOINT_W;
477 case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE:
478 *gen_type = HW_BREAKPOINT_RW;
486 case ARM_BREAKPOINT_LEN_1:
487 *gen_len = HW_BREAKPOINT_LEN_1;
489 case ARM_BREAKPOINT_LEN_2:
490 *gen_len = HW_BREAKPOINT_LEN_2;
492 case ARM_BREAKPOINT_LEN_4:
493 *gen_len = HW_BREAKPOINT_LEN_4;
495 case ARM_BREAKPOINT_LEN_8:
496 *gen_len = HW_BREAKPOINT_LEN_8;
506 * Construct an arch_hw_breakpoint from a perf_event.
508 static int arch_build_bp_info(struct perf_event *bp)
510 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
513 switch (bp->attr.bp_type) {
514 case HW_BREAKPOINT_X:
515 info->ctrl.type = ARM_BREAKPOINT_EXECUTE;
517 case HW_BREAKPOINT_R:
518 info->ctrl.type = ARM_BREAKPOINT_LOAD;
520 case HW_BREAKPOINT_W:
521 info->ctrl.type = ARM_BREAKPOINT_STORE;
523 case HW_BREAKPOINT_RW:
524 info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
531 switch (bp->attr.bp_len) {
532 case HW_BREAKPOINT_LEN_1:
533 info->ctrl.len = ARM_BREAKPOINT_LEN_1;
535 case HW_BREAKPOINT_LEN_2:
536 info->ctrl.len = ARM_BREAKPOINT_LEN_2;
538 case HW_BREAKPOINT_LEN_4:
539 info->ctrl.len = ARM_BREAKPOINT_LEN_4;
541 case HW_BREAKPOINT_LEN_8:
542 info->ctrl.len = ARM_BREAKPOINT_LEN_8;
543 if ((info->ctrl.type != ARM_BREAKPOINT_EXECUTE)
544 && max_watchpoint_len >= 8)
551 * Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes.
552 * Watchpoints can be of length 1, 2, 4 or 8 bytes if supported
553 * by the hardware and must be aligned to the appropriate number of
556 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE &&
557 info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
558 info->ctrl.len != ARM_BREAKPOINT_LEN_4)
562 info->address = bp->attr.bp_addr;
565 info->ctrl.privilege = ARM_BREAKPOINT_USER;
566 if (arch_check_bp_in_kernelspace(bp))
567 info->ctrl.privilege |= ARM_BREAKPOINT_PRIV;
570 info->ctrl.enabled = !bp->attr.disabled;
573 info->ctrl.mismatch = 0;
579 * Validate the arch-specific HW Breakpoint register settings.
581 int arch_validate_hwbkpt_settings(struct perf_event *bp)
583 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
585 u32 offset, alignment_mask = 0x3;
587 /* Build the arch_hw_breakpoint. */
588 ret = arch_build_bp_info(bp);
592 /* Check address alignment. */
593 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
594 alignment_mask = 0x7;
595 offset = info->address & alignment_mask;
601 /* Allow single byte watchpoint. */
602 if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
605 /* Allow halfword watchpoints and breakpoints. */
606 if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
613 info->address &= ~alignment_mask;
614 info->ctrl.len <<= offset;
617 * Currently we rely on an overflow handler to take
618 * care of single-stepping the breakpoint when it fires.
619 * In the case of userspace breakpoints on a core with V7 debug,
620 * we can use the mismatch feature as a poor-man's hardware single-step.
622 if (WARN_ONCE(!bp->overflow_handler &&
623 (arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_brps()),
624 "overflow handler required but none found")) {
631 static void update_mismatch_flag(int idx, int flag)
633 struct perf_event *bp = __get_cpu_var(bp_on_reg[idx]);
634 struct arch_hw_breakpoint *info;
639 info = counter_arch_bp(bp);
641 /* Update the mismatch field to enter/exit `single-step' mode */
642 if (!bp->overflow_handler && info->ctrl.mismatch != flag) {
643 info->ctrl.mismatch = flag;
644 write_wb_reg(ARM_BASE_BCR + idx, encode_ctrl_reg(info->ctrl) | 0x1);
648 static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs)
651 struct perf_event *wp, **slots = __get_cpu_var(wp_on_reg);
652 struct arch_hw_breakpoint *info;
654 /* Without a disassembler, we can only handle 1 watchpoint. */
655 BUG_ON(core_num_wrps > 1);
657 for (i = 0; i < core_num_wrps; ++i) {
668 * The DFAR is an unknown value. Since we only allow a
669 * single watchpoint, we can set the trigger to the lowest
670 * possible faulting address.
672 info = counter_arch_bp(wp);
673 info->trigger = wp->attr.bp_addr;
674 pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
675 perf_bp_event(wp, regs);
678 * If no overflow handler is present, insert a temporary
679 * mismatch breakpoint so we can single-step over the
680 * watchpoint trigger.
682 if (!wp->overflow_handler) {
683 arch_uninstall_hw_breakpoint(wp);
684 info->step_ctrl.mismatch = 1;
685 info->step_ctrl.len = ARM_BREAKPOINT_LEN_4;
686 info->step_ctrl.type = ARM_BREAKPOINT_EXECUTE;
687 info->step_ctrl.privilege = info->ctrl.privilege;
688 info->step_ctrl.enabled = 1;
689 info->trigger = regs->ARM_pc;
690 arch_install_hw_breakpoint(wp);
697 static void watchpoint_single_step_handler(unsigned long pc)
700 struct perf_event *wp, **slots = __get_cpu_var(wp_on_reg);
701 struct arch_hw_breakpoint *info;
703 for (i = 0; i < core_num_reserved_brps; ++i) {
711 info = counter_arch_bp(wp);
712 if (!info->step_ctrl.enabled)
716 * Restore the original watchpoint if we've completed the
719 if (info->trigger != pc) {
720 arch_uninstall_hw_breakpoint(wp);
721 info->step_ctrl.enabled = 0;
722 arch_install_hw_breakpoint(wp);
730 static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
734 u32 ctrl_reg, val, addr;
735 struct perf_event *bp, **slots = __get_cpu_var(bp_on_reg);
736 struct arch_hw_breakpoint *info;
737 struct arch_hw_breakpoint_ctrl ctrl;
739 /* The exception entry code places the amended lr in the PC. */
742 /* Check the currently installed breakpoints first. */
743 for (i = 0; i < core_num_brps; ++i) {
755 /* Check if the breakpoint value matches. */
756 val = read_wb_reg(ARM_BASE_BVR + i);
757 if (val != (addr & ~0x3))
760 /* Possible match, check the byte address select to confirm. */
761 ctrl_reg = read_wb_reg(ARM_BASE_BCR + i);
762 decode_ctrl_reg(ctrl_reg, &ctrl);
763 if ((1 << (addr & 0x3)) & ctrl.len) {
765 info = counter_arch_bp(bp);
766 info->trigger = addr;
770 if (mismatch && !info->ctrl.mismatch) {
771 pr_debug("breakpoint fired: address = 0x%x\n", addr);
772 perf_bp_event(bp, regs);
775 update_mismatch_flag(i, mismatch);
779 /* Handle any pending watchpoint single-step breakpoints. */
780 watchpoint_single_step_handler(addr);
784 * Called from either the Data Abort Handler [watchpoint] or the
785 * Prefetch Abort Handler [breakpoint] with preemption disabled.
787 static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
788 struct pt_regs *regs)
793 /* We must be called with preemption disabled. */
794 WARN_ON(preemptible());
796 /* We only handle watchpoints and hardware breakpoints. */
797 ARM_DBG_READ(c1, 0, dscr);
799 /* Perform perf callbacks. */
800 switch (ARM_DSCR_MOE(dscr)) {
801 case ARM_ENTRY_BREAKPOINT:
802 breakpoint_handler(addr, regs);
804 case ARM_ENTRY_ASYNC_WATCHPOINT:
805 WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
806 case ARM_ENTRY_SYNC_WATCHPOINT:
807 watchpoint_handler(addr, regs);
810 ret = 1; /* Unhandled fault. */
814 * Re-enable preemption after it was disabled in the
815 * low-level exception handling code.
823 * One-time initialisation.
825 static void reset_ctrl_regs(void *unused)
830 * v7 debug contains save and restore registers so that debug state
831 * can be maintained across low-power modes without leaving
832 * the debug logic powered up. It is IMPLEMENTATION DEFINED whether
833 * we can write to the debug registers out of reset, so we must
834 * unlock the OS Lock Access Register to avoid taking undefined
835 * instruction exceptions later on.
837 if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) {
839 * Unconditionally clear the lock by writing a value
840 * other than 0xC5ACCE55 to the access register.
842 asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
846 if (enable_monitor_mode())
849 /* We must also reset any reserved registers. */
850 for (i = 0; i < core_num_brps + core_num_reserved_brps; ++i) {
851 write_wb_reg(ARM_BASE_BCR + i, 0UL);
852 write_wb_reg(ARM_BASE_BVR + i, 0UL);
855 for (i = 0; i < core_num_wrps; ++i) {
856 write_wb_reg(ARM_BASE_WCR + i, 0UL);
857 write_wb_reg(ARM_BASE_WVR + i, 0UL);
861 static int __cpuinit dbg_reset_notify(struct notifier_block *self,
862 unsigned long action, void *cpu)
864 if (action == CPU_ONLINE)
865 smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
869 static struct notifier_block __cpuinitdata dbg_reset_nb = {
870 .notifier_call = dbg_reset_notify,
873 static int __init arch_hw_breakpoint_init(void)
878 debug_arch = get_debug_arch();
880 if (debug_arch > ARM_DEBUG_ARCH_V7_ECP14) {
881 pr_info("debug architecture 0x%x unsupported.\n", debug_arch);
886 /* Determine how many BRPs/WRPs are available. */
887 core_num_brps = get_num_brps();
888 core_num_reserved_brps = get_num_reserved_brps();
889 core_num_wrps = get_num_wrps();
891 pr_info("found %d breakpoint and %d watchpoint registers.\n",
892 core_num_brps + core_num_reserved_brps, core_num_wrps);
894 if (core_num_reserved_brps)
895 pr_info("%d breakpoint(s) reserved for watchpoint "
896 "single-step.\n", core_num_reserved_brps);
898 ARM_DBG_READ(c1, 0, dscr);
899 if (dscr & ARM_DSCR_HDBGEN) {
900 pr_warning("halting debug mode enabled. Assuming maximum "
901 "watchpoint size of 4 bytes.");
904 * Reset the breakpoint resources. We assume that a halting
905 * debugger will leave the world in a nice state for us.
907 smp_call_function(reset_ctrl_regs, NULL, 1);
908 reset_ctrl_regs(NULL);
910 /* Work out the maximum supported watchpoint length. */
911 max_watchpoint_len = get_max_wp_len();
912 pr_info("maximum watchpoint size is %u bytes.\n",
916 /* Register debug fault handler. */
917 hook_fault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
918 "watchpoint debug exception");
919 hook_ifault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
920 "breakpoint debug exception");
922 /* Register hotplug notifier. */
923 register_cpu_notifier(&dbg_reset_nb);
927 arch_initcall(arch_hw_breakpoint_init);
929 void hw_breakpoint_pmu_read(struct perf_event *bp)
934 * Dummy function to register with die_notifier.
936 int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
937 unsigned long val, void *data)