kgdb.c revision 166d751479c6d4e5b17dfc1f204a9c4397c9b3f1 
1/*
2 * This program is free software; you can redistribute it and/or modify it
3 * under the terms of the GNU General Public License as published by the
4 * Free Software Foundation; either version 2, or (at your option) any
5 * later version.
6 *
7 * This program is distributed in the hope that it will be useful, but
8 * WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
10 * General Public License for more details.
11 *
12 */
13
14/*
15 * Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com>
16 * Copyright (C) 2000-2001 VERITAS Software Corporation.
17 * Copyright (C) 2002 Andi Kleen, SuSE Labs
18 * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd.
19 * Copyright (C) 2007 MontaVista Software, Inc.
20 * Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc.
21 */
22/****************************************************************************
23 *  Contributor:     Lake Stevens Instrument Division$
24 *  Written by:      Glenn Engel $
25 *  Updated by:	     Amit Kale<akale@veritas.com>
26 *  Updated by:	     Tom Rini <trini@kernel.crashing.org>
27 *  Updated by:	     Jason Wessel <jason.wessel@windriver.com>
28 *  Modified for 386 by Jim Kingdon, Cygnus Support.
29 *  Origianl kgdb, compatibility with 2.1.xx kernel by
30 *  David Grothe <dave@gcom.com>
31 *  Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com>
32 *  X86_64 changes from Andi Kleen's patch merged by Jim Houston
33 */
34#include <linux/spinlock.h>
35#include <linux/kdebug.h>
36#include <linux/string.h>
37#include <linux/kernel.h>
38#include <linux/ptrace.h>
39#include <linux/sched.h>
40#include <linux/delay.h>
41#include <linux/kgdb.h>
42#include <linux/init.h>
43#include <linux/smp.h>
44#include <linux/nmi.h>
45#include <linux/hw_breakpoint.h>
46
47#include <asm/debugreg.h>
48#include <asm/apicdef.h>
49#include <asm/system.h>
50#include <asm/apic.h>
51#include <asm/nmi.h>
52
53struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
54{
55#ifdef CONFIG_X86_32
56	{ "ax", 4, offsetof(struct pt_regs, ax) },
57	{ "cx", 4, offsetof(struct pt_regs, cx) },
58	{ "dx", 4, offsetof(struct pt_regs, dx) },
59	{ "bx", 4, offsetof(struct pt_regs, bx) },
60	{ "sp", 4, offsetof(struct pt_regs, sp) },
61	{ "bp", 4, offsetof(struct pt_regs, bp) },
62	{ "si", 4, offsetof(struct pt_regs, si) },
63	{ "di", 4, offsetof(struct pt_regs, di) },
64	{ "ip", 4, offsetof(struct pt_regs, ip) },
65	{ "flags", 4, offsetof(struct pt_regs, flags) },
66	{ "cs", 4, offsetof(struct pt_regs, cs) },
67	{ "ss", 4, offsetof(struct pt_regs, ss) },
68	{ "ds", 4, offsetof(struct pt_regs, ds) },
69	{ "es", 4, offsetof(struct pt_regs, es) },
70	{ "fs", 4, -1 },
71	{ "gs", 4, -1 },
72#else
73	{ "ax", 8, offsetof(struct pt_regs, ax) },
74	{ "bx", 8, offsetof(struct pt_regs, bx) },
75	{ "cx", 8, offsetof(struct pt_regs, cx) },
76	{ "dx", 8, offsetof(struct pt_regs, dx) },
77	{ "si", 8, offsetof(struct pt_regs, dx) },
78	{ "di", 8, offsetof(struct pt_regs, di) },
79	{ "bp", 8, offsetof(struct pt_regs, bp) },
80	{ "sp", 8, offsetof(struct pt_regs, sp) },
81	{ "r8", 8, offsetof(struct pt_regs, r8) },
82	{ "r9", 8, offsetof(struct pt_regs, r9) },
83	{ "r10", 8, offsetof(struct pt_regs, r10) },
84	{ "r11", 8, offsetof(struct pt_regs, r11) },
85	{ "r12", 8, offsetof(struct pt_regs, r12) },
86	{ "r13", 8, offsetof(struct pt_regs, r13) },
87	{ "r14", 8, offsetof(struct pt_regs, r14) },
88	{ "r15", 8, offsetof(struct pt_regs, r15) },
89	{ "ip", 8, offsetof(struct pt_regs, ip) },
90	{ "flags", 4, offsetof(struct pt_regs, flags) },
91	{ "cs", 4, offsetof(struct pt_regs, cs) },
92	{ "ss", 4, offsetof(struct pt_regs, ss) },
93#endif
94};
95
96int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
97{
98	if (
99#ifdef CONFIG_X86_32
100	    regno == GDB_SS || regno == GDB_FS || regno == GDB_GS ||
101#endif
102	    regno == GDB_SP || regno == GDB_ORIG_AX)
103		return 0;
104
105	if (dbg_reg_def[regno].offset != -1)
106		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
107		       dbg_reg_def[regno].size);
108	return 0;
109}
110
111char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
112{
113	if (regno == GDB_ORIG_AX) {
114		memcpy(mem, &regs->orig_ax, sizeof(regs->orig_ax));
115		return "orig_ax";
116	}
117	if (regno >= DBG_MAX_REG_NUM || regno < 0)
118		return NULL;
119
120	if (dbg_reg_def[regno].offset != -1)
121		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
122		       dbg_reg_def[regno].size);
123
124	switch (regno) {
125#ifdef CONFIG_X86_32
126	case GDB_SS:
127		if (!user_mode_vm(regs))
128			*(unsigned long *)mem = __KERNEL_DS;
129		break;
130	case GDB_SP:
131		if (!user_mode_vm(regs))
132			*(unsigned long *)mem = kernel_stack_pointer(regs);
133		break;
134	case GDB_GS:
135	case GDB_FS:
136		*(unsigned long *)mem = 0xFFFF;
137		break;
138#endif
139	}
140	return dbg_reg_def[regno].name;
141}
142
143/**
144 *	sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
145 *	@gdb_regs: A pointer to hold the registers in the order GDB wants.
146 *	@p: The &struct task_struct of the desired process.
147 *
148 *	Convert the register values of the sleeping process in @p to
149 *	the format that GDB expects.
150 *	This function is called when kgdb does not have access to the
151 *	&struct pt_regs and therefore it should fill the gdb registers
152 *	@gdb_regs with what has	been saved in &struct thread_struct
153 *	thread field during switch_to.
154 */
155void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
156{
157#ifndef CONFIG_X86_32
158	u32 *gdb_regs32 = (u32 *)gdb_regs;
159#endif
160	gdb_regs[GDB_AX]	= 0;
161	gdb_regs[GDB_BX]	= 0;
162	gdb_regs[GDB_CX]	= 0;
163	gdb_regs[GDB_DX]	= 0;
164	gdb_regs[GDB_SI]	= 0;
165	gdb_regs[GDB_DI]	= 0;
166	gdb_regs[GDB_BP]	= *(unsigned long *)p->thread.sp;
167#ifdef CONFIG_X86_32
168	gdb_regs[GDB_DS]	= __KERNEL_DS;
169	gdb_regs[GDB_ES]	= __KERNEL_DS;
170	gdb_regs[GDB_PS]	= 0;
171	gdb_regs[GDB_CS]	= __KERNEL_CS;
172	gdb_regs[GDB_PC]	= p->thread.ip;
173	gdb_regs[GDB_SS]	= __KERNEL_DS;
174	gdb_regs[GDB_FS]	= 0xFFFF;
175	gdb_regs[GDB_GS]	= 0xFFFF;
176#else
177	gdb_regs32[GDB_PS]	= *(unsigned long *)(p->thread.sp + 8);
178	gdb_regs32[GDB_CS]	= __KERNEL_CS;
179	gdb_regs32[GDB_SS]	= __KERNEL_DS;
180	gdb_regs[GDB_PC]	= 0;
181	gdb_regs[GDB_R8]	= 0;
182	gdb_regs[GDB_R9]	= 0;
183	gdb_regs[GDB_R10]	= 0;
184	gdb_regs[GDB_R11]	= 0;
185	gdb_regs[GDB_R12]	= 0;
186	gdb_regs[GDB_R13]	= 0;
187	gdb_regs[GDB_R14]	= 0;
188	gdb_regs[GDB_R15]	= 0;
189#endif
190	gdb_regs[GDB_SP]	= p->thread.sp;
191}
192
193static struct hw_breakpoint {
194	unsigned		enabled;
195	unsigned long		addr;
196	int			len;
197	int			type;
198	struct perf_event	* __percpu *pev;
199} breakinfo[HBP_NUM];
200
201static unsigned long early_dr7;
202
203static void kgdb_correct_hw_break(void)
204{
205	int breakno;
206
207	for (breakno = 0; breakno < HBP_NUM; breakno++) {
208		struct perf_event *bp;
209		struct arch_hw_breakpoint *info;
210		int val;
211		int cpu = raw_smp_processor_id();
212		if (!breakinfo[breakno].enabled)
213			continue;
214		if (dbg_is_early) {
215			set_debugreg(breakinfo[breakno].addr, breakno);
216			early_dr7 |= encode_dr7(breakno,
217						breakinfo[breakno].len,
218						breakinfo[breakno].type);
219			set_debugreg(early_dr7, 7);
220			continue;
221		}
222		bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
223		info = counter_arch_bp(bp);
224		if (bp->attr.disabled != 1)
225			continue;
226		bp->attr.bp_addr = breakinfo[breakno].addr;
227		bp->attr.bp_len = breakinfo[breakno].len;
228		bp->attr.bp_type = breakinfo[breakno].type;
229		info->address = breakinfo[breakno].addr;
230		info->len = breakinfo[breakno].len;
231		info->type = breakinfo[breakno].type;
232		val = arch_install_hw_breakpoint(bp);
233		if (!val)
234			bp->attr.disabled = 0;
235	}
236	if (!dbg_is_early)
237		hw_breakpoint_restore();
238}
239
240static int hw_break_reserve_slot(int breakno)
241{
242	int cpu;
243	int cnt = 0;
244	struct perf_event **pevent;
245
246	if (dbg_is_early)
247		return 0;
248
249	for_each_online_cpu(cpu) {
250		cnt++;
251		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
252		if (dbg_reserve_bp_slot(*pevent))
253			goto fail;
254	}
255
256	return 0;
257
258fail:
259	for_each_online_cpu(cpu) {
260		cnt--;
261		if (!cnt)
262			break;
263		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
264		dbg_release_bp_slot(*pevent);
265	}
266	return -1;
267}
268
269static int hw_break_release_slot(int breakno)
270{
271	struct perf_event **pevent;
272	int cpu;
273
274	if (dbg_is_early)
275		return 0;
276
277	for_each_online_cpu(cpu) {
278		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
279		if (dbg_release_bp_slot(*pevent))
280			/*
281			 * The debugger is responisble for handing the retry on
282			 * remove failure.
283			 */
284			return -1;
285	}
286	return 0;
287}
288
289static int
290kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
291{
292	int i;
293
294	for (i = 0; i < HBP_NUM; i++)
295		if (breakinfo[i].addr == addr && breakinfo[i].enabled)
296			break;
297	if (i == HBP_NUM)
298		return -1;
299
300	if (hw_break_release_slot(i)) {
301		printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
302		return -1;
303	}
304	breakinfo[i].enabled = 0;
305
306	return 0;
307}
308
309static void kgdb_remove_all_hw_break(void)
310{
311	int i;
312	int cpu = raw_smp_processor_id();
313	struct perf_event *bp;
314
315	for (i = 0; i < HBP_NUM; i++) {
316		if (!breakinfo[i].enabled)
317			continue;
318		bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
319		if (!bp->attr.disabled) {
320			arch_uninstall_hw_breakpoint(bp);
321			bp->attr.disabled = 1;
322			continue;
323		}
324		if (dbg_is_early)
325			early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
326						 breakinfo[i].type);
327		else if (hw_break_release_slot(i))
328			printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
329			       breakinfo[i].addr);
330		breakinfo[i].enabled = 0;
331	}
332}
333
334static int
335kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
336{
337	int i;
338
339	for (i = 0; i < HBP_NUM; i++)
340		if (!breakinfo[i].enabled)
341			break;
342	if (i == HBP_NUM)
343		return -1;
344
345	switch (bptype) {
346	case BP_HARDWARE_BREAKPOINT:
347		len = 1;
348		breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
349		break;
350	case BP_WRITE_WATCHPOINT:
351		breakinfo[i].type = X86_BREAKPOINT_WRITE;
352		break;
353	case BP_ACCESS_WATCHPOINT:
354		breakinfo[i].type = X86_BREAKPOINT_RW;
355		break;
356	default:
357		return -1;
358	}
359	switch (len) {
360	case 1:
361		breakinfo[i].len = X86_BREAKPOINT_LEN_1;
362		break;
363	case 2:
364		breakinfo[i].len = X86_BREAKPOINT_LEN_2;
365		break;
366	case 4:
367		breakinfo[i].len = X86_BREAKPOINT_LEN_4;
368		break;
369#ifdef CONFIG_X86_64
370	case 8:
371		breakinfo[i].len = X86_BREAKPOINT_LEN_8;
372		break;
373#endif
374	default:
375		return -1;
376	}
377	breakinfo[i].addr = addr;
378	if (hw_break_reserve_slot(i)) {
379		breakinfo[i].addr = 0;
380		return -1;
381	}
382	breakinfo[i].enabled = 1;
383
384	return 0;
385}
386
387/**
388 *	kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
389 *	@regs: Current &struct pt_regs.
390 *
391 *	This function will be called if the particular architecture must
392 *	disable hardware debugging while it is processing gdb packets or
393 *	handling exception.
394 */
395static void kgdb_disable_hw_debug(struct pt_regs *regs)
396{
397	int i;
398	int cpu = raw_smp_processor_id();
399	struct perf_event *bp;
400
401	/* Disable hardware debugging while we are in kgdb: */
402	set_debugreg(0UL, 7);
403	for (i = 0; i < HBP_NUM; i++) {
404		if (!breakinfo[i].enabled)
405			continue;
406		if (dbg_is_early) {
407			early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
408						 breakinfo[i].type);
409			continue;
410		}
411		bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
412		if (bp->attr.disabled == 1)
413			continue;
414		arch_uninstall_hw_breakpoint(bp);
415		bp->attr.disabled = 1;
416	}
417}
418
419#ifdef CONFIG_SMP
420/**
421 *	kgdb_roundup_cpus - Get other CPUs into a holding pattern
422 *	@flags: Current IRQ state
423 *
424 *	On SMP systems, we need to get the attention of the other CPUs
425 *	and get them be in a known state.  This should do what is needed
426 *	to get the other CPUs to call kgdb_wait(). Note that on some arches,
427 *	the NMI approach is not used for rounding up all the CPUs. For example,
428 *	in case of MIPS, smp_call_function() is used to roundup CPUs. In
429 *	this case, we have to make sure that interrupts are enabled before
430 *	calling smp_call_function(). The argument to this function is
431 *	the flags that will be used when restoring the interrupts. There is
432 *	local_irq_save() call before kgdb_roundup_cpus().
433 *
434 *	On non-SMP systems, this is not called.
435 */
436void kgdb_roundup_cpus(unsigned long flags)
437{
438	apic->send_IPI_allbutself(APIC_DM_NMI);
439}
440#endif
441
442/**
443 *	kgdb_arch_handle_exception - Handle architecture specific GDB packets.
444 *	@vector: The error vector of the exception that happened.
445 *	@signo: The signal number of the exception that happened.
446 *	@err_code: The error code of the exception that happened.
447 *	@remcom_in_buffer: The buffer of the packet we have read.
448 *	@remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
449 *	@regs: The &struct pt_regs of the current process.
450 *
451 *	This function MUST handle the 'c' and 's' command packets,
452 *	as well packets to set / remove a hardware breakpoint, if used.
453 *	If there are additional packets which the hardware needs to handle,
454 *	they are handled here.  The code should return -1 if it wants to
455 *	process more packets, and a %0 or %1 if it wants to exit from the
456 *	kgdb callback.
457 */
458int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
459			       char *remcomInBuffer, char *remcomOutBuffer,
460			       struct pt_regs *linux_regs)
461{
462	unsigned long addr;
463	char *ptr;
464
465	switch (remcomInBuffer[0]) {
466	case 'c':
467	case 's':
468		/* try to read optional parameter, pc unchanged if no parm */
469		ptr = &remcomInBuffer[1];
470		if (kgdb_hex2long(&ptr, &addr))
471			linux_regs->ip = addr;
472	case 'D':
473	case 'k':
474		/* clear the trace bit */
475		linux_regs->flags &= ~X86_EFLAGS_TF;
476		atomic_set(&kgdb_cpu_doing_single_step, -1);
477
478		/* set the trace bit if we're stepping */
479		if (remcomInBuffer[0] == 's') {
480			linux_regs->flags |= X86_EFLAGS_TF;
481			atomic_set(&kgdb_cpu_doing_single_step,
482				   raw_smp_processor_id());
483		}
484
485		return 0;
486	}
487
488	/* this means that we do not want to exit from the handler: */
489	return -1;
490}
491
492static inline int
493single_step_cont(struct pt_regs *regs, struct die_args *args)
494{
495	/*
496	 * Single step exception from kernel space to user space so
497	 * eat the exception and continue the process:
498	 */
499	printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
500			"resuming...\n");
501	kgdb_arch_handle_exception(args->trapnr, args->signr,
502				   args->err, "c", "", regs);
503	/*
504	 * Reset the BS bit in dr6 (pointed by args->err) to
505	 * denote completion of processing
506	 */
507	(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
508
509	return NOTIFY_STOP;
510}
511
512static int was_in_debug_nmi[NR_CPUS];
513
514static int __kgdb_notify(struct die_args *args, unsigned long cmd)
515{
516	struct pt_regs *regs = args->regs;
517
518	switch (cmd) {
519	case DIE_NMI:
520		if (atomic_read(&kgdb_active) != -1) {
521			/* KGDB CPU roundup */
522			kgdb_nmicallback(raw_smp_processor_id(), regs);
523			was_in_debug_nmi[raw_smp_processor_id()] = 1;
524			touch_nmi_watchdog();
525			return NOTIFY_STOP;
526		}
527		return NOTIFY_DONE;
528
529	case DIE_NMI_IPI:
530		/* Just ignore, we will handle the roundup on DIE_NMI. */
531		return NOTIFY_DONE;
532
533	case DIE_NMIUNKNOWN:
534		if (was_in_debug_nmi[raw_smp_processor_id()]) {
535			was_in_debug_nmi[raw_smp_processor_id()] = 0;
536			return NOTIFY_STOP;
537		}
538		return NOTIFY_DONE;
539
540	case DIE_NMIWATCHDOG:
541		if (atomic_read(&kgdb_active) != -1) {
542			/* KGDB CPU roundup: */
543			kgdb_nmicallback(raw_smp_processor_id(), regs);
544			return NOTIFY_STOP;
545		}
546		/* Enter debugger: */
547		break;
548
549	case DIE_DEBUG:
550		if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
551			if (user_mode(regs))
552				return single_step_cont(regs, args);
553			break;
554		} else if (test_thread_flag(TIF_SINGLESTEP))
555			/* This means a user thread is single stepping
556			 * a system call which should be ignored
557			 */
558			return NOTIFY_DONE;
559		/* fall through */
560	default:
561		if (user_mode(regs))
562			return NOTIFY_DONE;
563	}
564
565	if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
566		return NOTIFY_DONE;
567
568	/* Must touch watchdog before return to normal operation */
569	touch_nmi_watchdog();
570	return NOTIFY_STOP;
571}
572
573int kgdb_ll_trap(int cmd, const char *str,
574		 struct pt_regs *regs, long err, int trap, int sig)
575{
576	struct die_args args = {
577		.regs	= regs,
578		.str	= str,
579		.err	= err,
580		.trapnr	= trap,
581		.signr	= sig,
582
583	};
584
585	if (!kgdb_io_module_registered)
586		return NOTIFY_DONE;
587
588	return __kgdb_notify(&args, cmd);
589}
590
591static int
592kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
593{
594	unsigned long flags;
595	int ret;
596
597	local_irq_save(flags);
598	ret = __kgdb_notify(ptr, cmd);
599	local_irq_restore(flags);
600
601	return ret;
602}
603
604static struct notifier_block kgdb_notifier = {
605	.notifier_call	= kgdb_notify,
606
607	/*
608	 * Lowest-prio notifier priority, we want to be notified last:
609	 */
610	.priority	= NMI_LOCAL_LOW_PRIOR,
611};
612
613/**
614 *	kgdb_arch_init - Perform any architecture specific initalization.
615 *
616 *	This function will handle the initalization of any architecture
617 *	specific callbacks.
618 */
619int kgdb_arch_init(void)
620{
621	return register_die_notifier(&kgdb_notifier);
622}
623
624static void kgdb_hw_overflow_handler(struct perf_event *event, int nmi,
625		struct perf_sample_data *data, struct pt_regs *regs)
626{
627	struct task_struct *tsk = current;
628	int i;
629
630	for (i = 0; i < 4; i++)
631		if (breakinfo[i].enabled)
632			tsk->thread.debugreg6 |= (DR_TRAP0 << i);
633}
634
635void kgdb_arch_late(void)
636{
637	int i, cpu;
638	struct perf_event_attr attr;
639	struct perf_event **pevent;
640
641	/*
642	 * Pre-allocate the hw breakpoint structions in the non-atomic
643	 * portion of kgdb because this operation requires mutexs to
644	 * complete.
645	 */
646	hw_breakpoint_init(&attr);
647	attr.bp_addr = (unsigned long)kgdb_arch_init;
648	attr.bp_len = HW_BREAKPOINT_LEN_1;
649	attr.bp_type = HW_BREAKPOINT_W;
650	attr.disabled = 1;
651	for (i = 0; i < HBP_NUM; i++) {
652		if (breakinfo[i].pev)
653			continue;
654		breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
655		if (IS_ERR((void * __force)breakinfo[i].pev)) {
656			printk(KERN_ERR "kgdb: Could not allocate hw"
657			       "breakpoints\nDisabling the kernel debugger\n");
658			breakinfo[i].pev = NULL;
659			kgdb_arch_exit();
660			return;
661		}
662		for_each_online_cpu(cpu) {
663			pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
664			pevent[0]->hw.sample_period = 1;
665			pevent[0]->overflow_handler = kgdb_hw_overflow_handler;
666			if (pevent[0]->destroy != NULL) {
667				pevent[0]->destroy = NULL;
668				release_bp_slot(*pevent);
669			}
670		}
671	}
672}
673
674/**
675 *	kgdb_arch_exit - Perform any architecture specific uninitalization.
676 *
677 *	This function will handle the uninitalization of any architecture
678 *	specific callbacks, for dynamic registration and unregistration.
679 */
680void kgdb_arch_exit(void)
681{
682	int i;
683	for (i = 0; i < 4; i++) {
684		if (breakinfo[i].pev) {
685			unregister_wide_hw_breakpoint(breakinfo[i].pev);
686			breakinfo[i].pev = NULL;
687		}
688	}
689	unregister_die_notifier(&kgdb_notifier);
690}
691
692/**
693 *
694 *	kgdb_skipexception - Bail out of KGDB when we've been triggered.
695 *	@exception: Exception vector number
696 *	@regs: Current &struct pt_regs.
697 *
698 *	On some architectures we need to skip a breakpoint exception when
699 *	it occurs after a breakpoint has been removed.
700 *
701 * Skip an int3 exception when it occurs after a breakpoint has been
702 * removed. Backtrack eip by 1 since the int3 would have caused it to
703 * increment by 1.
704 */
705int kgdb_skipexception(int exception, struct pt_regs *regs)
706{
707	if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
708		regs->ip -= 1;
709		return 1;
710	}
711	return 0;
712}
713
714unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
715{
716	if (exception == 3)
717		return instruction_pointer(regs) - 1;
718	return instruction_pointer(regs);
719}
720
721void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
722{
723	regs->ip = ip;
724}
725
726struct kgdb_arch arch_kgdb_ops = {
727	/* Breakpoint instruction: */
728	.gdb_bpt_instr		= { 0xcc },
729	.flags			= KGDB_HW_BREAKPOINT,
730	.set_hw_breakpoint	= kgdb_set_hw_break,
731	.remove_hw_breakpoint	= kgdb_remove_hw_break,
732	.disable_hw_break	= kgdb_disable_hw_debug,
733	.remove_all_hw_break	= kgdb_remove_all_hw_break,
734	.correct_hw_break	= kgdb_correct_hw_break,
735};
736