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;
342 if (info->step_ctrl.enabled) {
343 /* Override the breakpoint data with the step data. */
344 addr = info->trigger & ~0x3;
345 ctrl = encode_ctrl_reg(info->step_ctrl);
349 if (info->step_ctrl.enabled) {
350 /* Install into the reserved breakpoint region. */
351 ctrl_base = ARM_BASE_BCR + core_num_brps;
352 val_base = ARM_BASE_BVR + core_num_brps;
353 /* Override the watchpoint data with the step data. */
354 addr = info->trigger & ~0x3;
355 ctrl = encode_ctrl_reg(info->step_ctrl);
357 ctrl_base = ARM_BASE_WCR;
358 val_base = ARM_BASE_WVR;
360 slots = __get_cpu_var(wp_on_reg);
361 max_slots = core_num_wrps;
364 for (i = 0; i < max_slots; ++i) {
373 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot")) {
378 /* Setup the address register. */
379 write_wb_reg(val_base + i, addr);
381 /* Setup the control register. */
382 write_wb_reg(ctrl_base + i, ctrl);
388 void arch_uninstall_hw_breakpoint(struct perf_event *bp)
390 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
391 struct perf_event **slot, **slots;
392 int i, max_slots, base;
394 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
397 slots = __get_cpu_var(bp_on_reg);
398 max_slots = core_num_brps;
401 if (info->step_ctrl.enabled)
402 base = ARM_BASE_BCR + core_num_brps;
405 slots = __get_cpu_var(wp_on_reg);
406 max_slots = core_num_wrps;
409 /* Remove the breakpoint. */
410 for (i = 0; i < max_slots; ++i) {
419 if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot"))
422 /* Reset the control register. */
423 write_wb_reg(base + i, 0);
426 static int get_hbp_len(u8 hbp_len)
428 unsigned int len_in_bytes = 0;
431 case ARM_BREAKPOINT_LEN_1:
434 case ARM_BREAKPOINT_LEN_2:
437 case ARM_BREAKPOINT_LEN_4:
440 case ARM_BREAKPOINT_LEN_8:
449 * Check whether bp virtual address is in kernel space.
451 int arch_check_bp_in_kernelspace(struct perf_event *bp)
455 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
458 len = get_hbp_len(info->ctrl.len);
460 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
464 * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
465 * Hopefully this will disappear when ptrace can bypass the conversion
466 * to generic breakpoint descriptions.
468 int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
469 int *gen_len, int *gen_type)
473 case ARM_BREAKPOINT_EXECUTE:
474 *gen_type = HW_BREAKPOINT_X;
476 case ARM_BREAKPOINT_LOAD:
477 *gen_type = HW_BREAKPOINT_R;
479 case ARM_BREAKPOINT_STORE:
480 *gen_type = HW_BREAKPOINT_W;
482 case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE:
483 *gen_type = HW_BREAKPOINT_RW;
491 case ARM_BREAKPOINT_LEN_1:
492 *gen_len = HW_BREAKPOINT_LEN_1;
494 case ARM_BREAKPOINT_LEN_2:
495 *gen_len = HW_BREAKPOINT_LEN_2;
497 case ARM_BREAKPOINT_LEN_4:
498 *gen_len = HW_BREAKPOINT_LEN_4;
500 case ARM_BREAKPOINT_LEN_8:
501 *gen_len = HW_BREAKPOINT_LEN_8;
511 * Construct an arch_hw_breakpoint from a perf_event.
513 static int arch_build_bp_info(struct perf_event *bp)
515 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
518 switch (bp->attr.bp_type) {
519 case HW_BREAKPOINT_X:
520 info->ctrl.type = ARM_BREAKPOINT_EXECUTE;
522 case HW_BREAKPOINT_R:
523 info->ctrl.type = ARM_BREAKPOINT_LOAD;
525 case HW_BREAKPOINT_W:
526 info->ctrl.type = ARM_BREAKPOINT_STORE;
528 case HW_BREAKPOINT_RW:
529 info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
536 switch (bp->attr.bp_len) {
537 case HW_BREAKPOINT_LEN_1:
538 info->ctrl.len = ARM_BREAKPOINT_LEN_1;
540 case HW_BREAKPOINT_LEN_2:
541 info->ctrl.len = ARM_BREAKPOINT_LEN_2;
543 case HW_BREAKPOINT_LEN_4:
544 info->ctrl.len = ARM_BREAKPOINT_LEN_4;
546 case HW_BREAKPOINT_LEN_8:
547 info->ctrl.len = ARM_BREAKPOINT_LEN_8;
548 if ((info->ctrl.type != ARM_BREAKPOINT_EXECUTE)
549 && max_watchpoint_len >= 8)
556 * Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes.
557 * Watchpoints can be of length 1, 2, 4 or 8 bytes if supported
558 * by the hardware and must be aligned to the appropriate number of
561 if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE &&
562 info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
563 info->ctrl.len != ARM_BREAKPOINT_LEN_4)
567 info->address = bp->attr.bp_addr;
570 info->ctrl.privilege = ARM_BREAKPOINT_USER;
571 if (arch_check_bp_in_kernelspace(bp))
572 info->ctrl.privilege |= ARM_BREAKPOINT_PRIV;
575 info->ctrl.enabled = !bp->attr.disabled;
578 info->ctrl.mismatch = 0;
584 * Validate the arch-specific HW Breakpoint register settings.
586 int arch_validate_hwbkpt_settings(struct perf_event *bp)
588 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
590 u32 offset, alignment_mask = 0x3;
592 /* Build the arch_hw_breakpoint. */
593 ret = arch_build_bp_info(bp);
597 /* Check address alignment. */
598 if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
599 alignment_mask = 0x7;
600 offset = info->address & alignment_mask;
606 /* Allow single byte watchpoint. */
607 if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
610 /* Allow halfword watchpoints and breakpoints. */
611 if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
618 info->address &= ~alignment_mask;
619 info->ctrl.len <<= offset;
622 * Currently we rely on an overflow handler to take
623 * care of single-stepping the breakpoint when it fires.
624 * In the case of userspace breakpoints on a core with V7 debug,
625 * we can use the mismatch feature as a poor-man's hardware
626 * single-step, but this only works for per-task breakpoints.
628 if (WARN_ONCE(!bp->overflow_handler &&
629 (arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_brps()
630 || !bp->hw.bp_target),
631 "overflow handler required but none found")) {
639 * Enable/disable single-stepping over the breakpoint bp at address addr.
641 static void enable_single_step(struct perf_event *bp, u32 addr)
643 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
645 arch_uninstall_hw_breakpoint(bp);
646 info->step_ctrl.mismatch = 1;
647 info->step_ctrl.len = ARM_BREAKPOINT_LEN_4;
648 info->step_ctrl.type = ARM_BREAKPOINT_EXECUTE;
649 info->step_ctrl.privilege = info->ctrl.privilege;
650 info->step_ctrl.enabled = 1;
651 info->trigger = addr;
652 arch_install_hw_breakpoint(bp);
655 static void disable_single_step(struct perf_event *bp)
657 arch_uninstall_hw_breakpoint(bp);
658 counter_arch_bp(bp)->step_ctrl.enabled = 0;
659 arch_install_hw_breakpoint(bp);
662 static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs)
665 struct perf_event *wp, **slots = __get_cpu_var(wp_on_reg);
666 struct arch_hw_breakpoint *info;
668 /* Without a disassembler, we can only handle 1 watchpoint. */
669 BUG_ON(core_num_wrps > 1);
671 for (i = 0; i < core_num_wrps; ++i) {
682 * The DFAR is an unknown value. Since we only allow a
683 * single watchpoint, we can set the trigger to the lowest
684 * possible faulting address.
686 info = counter_arch_bp(wp);
687 info->trigger = wp->attr.bp_addr;
688 pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
689 perf_bp_event(wp, regs);
692 * If no overflow handler is present, insert a temporary
693 * mismatch breakpoint so we can single-step over the
694 * watchpoint trigger.
696 if (!wp->overflow_handler)
697 enable_single_step(wp, instruction_pointer(regs));
703 static void watchpoint_single_step_handler(unsigned long pc)
706 struct perf_event *wp, **slots = __get_cpu_var(wp_on_reg);
707 struct arch_hw_breakpoint *info;
709 for (i = 0; i < core_num_reserved_brps; ++i) {
717 info = counter_arch_bp(wp);
718 if (!info->step_ctrl.enabled)
722 * Restore the original watchpoint if we've completed the
725 if (info->trigger != pc)
726 disable_single_step(wp);
733 static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
736 u32 ctrl_reg, val, addr;
737 struct perf_event *bp, **slots = __get_cpu_var(bp_on_reg);
738 struct arch_hw_breakpoint *info;
739 struct arch_hw_breakpoint_ctrl ctrl;
741 /* The exception entry code places the amended lr in the PC. */
744 /* Check the currently installed breakpoints first. */
745 for (i = 0; i < core_num_brps; ++i) {
753 info = counter_arch_bp(bp);
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) {
764 info->trigger = addr;
765 pr_debug("breakpoint fired: address = 0x%x\n", addr);
766 perf_bp_event(bp, regs);
767 if (!bp->overflow_handler)
768 enable_single_step(bp, addr);
773 /* If we're stepping a breakpoint, it can now be restored. */
774 if (info->step_ctrl.enabled)
775 disable_single_step(bp);
780 /* Handle any pending watchpoint single-step breakpoints. */
781 watchpoint_single_step_handler(addr);
785 * Called from either the Data Abort Handler [watchpoint] or the
786 * Prefetch Abort Handler [breakpoint] with preemption disabled.
788 static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
789 struct pt_regs *regs)
794 /* We must be called with preemption disabled. */
795 WARN_ON(preemptible());
797 /* We only handle watchpoints and hardware breakpoints. */
798 ARM_DBG_READ(c1, 0, dscr);
800 /* Perform perf callbacks. */
801 switch (ARM_DSCR_MOE(dscr)) {
802 case ARM_ENTRY_BREAKPOINT:
803 breakpoint_handler(addr, regs);
805 case ARM_ENTRY_ASYNC_WATCHPOINT:
806 WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
807 case ARM_ENTRY_SYNC_WATCHPOINT:
808 watchpoint_handler(addr, regs);
811 ret = 1; /* Unhandled fault. */
815 * Re-enable preemption after it was disabled in the
816 * low-level exception handling code.
824 * One-time initialisation.
826 static void reset_ctrl_regs(void *unused)
831 * v7 debug contains save and restore registers so that debug state
832 * can be maintained across low-power modes without leaving
833 * the debug logic powered up. It is IMPLEMENTATION DEFINED whether
834 * we can write to the debug registers out of reset, so we must
835 * unlock the OS Lock Access Register to avoid taking undefined
836 * instruction exceptions later on.
838 if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) {
840 * Unconditionally clear the lock by writing a value
841 * other than 0xC5ACCE55 to the access register.
843 asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
847 if (enable_monitor_mode())
850 /* We must also reset any reserved registers. */
851 for (i = 0; i < core_num_brps + core_num_reserved_brps; ++i) {
852 write_wb_reg(ARM_BASE_BCR + i, 0UL);
853 write_wb_reg(ARM_BASE_BVR + i, 0UL);
856 for (i = 0; i < core_num_wrps; ++i) {
857 write_wb_reg(ARM_BASE_WCR + i, 0UL);
858 write_wb_reg(ARM_BASE_WVR + i, 0UL);
862 static int __cpuinit dbg_reset_notify(struct notifier_block *self,
863 unsigned long action, void *cpu)
865 if (action == CPU_ONLINE)
866 smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
870 static struct notifier_block __cpuinitdata dbg_reset_nb = {
871 .notifier_call = dbg_reset_notify,
874 static int __init arch_hw_breakpoint_init(void)
879 debug_arch = get_debug_arch();
881 if (debug_arch > ARM_DEBUG_ARCH_V7_ECP14) {
882 pr_info("debug architecture 0x%x unsupported.\n", debug_arch);
887 /* Determine how many BRPs/WRPs are available. */
888 core_num_brps = get_num_brps();
889 core_num_reserved_brps = get_num_reserved_brps();
890 core_num_wrps = get_num_wrps();
892 pr_info("found %d breakpoint and %d watchpoint registers.\n",
893 core_num_brps + core_num_reserved_brps, core_num_wrps);
895 if (core_num_reserved_brps)
896 pr_info("%d breakpoint(s) reserved for watchpoint "
897 "single-step.\n", core_num_reserved_brps);
899 ARM_DBG_READ(c1, 0, dscr);
900 if (dscr & ARM_DSCR_HDBGEN) {
901 pr_warning("halting debug mode enabled. Assuming maximum "
902 "watchpoint size of 4 bytes.");
905 * Reset the breakpoint resources. We assume that a halting
906 * debugger will leave the world in a nice state for us.
908 smp_call_function(reset_ctrl_regs, NULL, 1);
909 reset_ctrl_regs(NULL);
911 /* Work out the maximum supported watchpoint length. */
912 max_watchpoint_len = get_max_wp_len();
913 pr_info("maximum watchpoint size is %u bytes.\n",
917 /* Register debug fault handler. */
918 hook_fault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
919 "watchpoint debug exception");
920 hook_ifault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
921 "breakpoint debug exception");
923 /* Register hotplug notifier. */
924 register_cpu_notifier(&dbg_reset_nb);
928 arch_initcall(arch_hw_breakpoint_init);
930 void hw_breakpoint_pmu_read(struct perf_event *bp)
935 * Dummy function to register with die_notifier.
937 int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
938 unsigned long val, void *data)