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#include <linux/uaccess.h>
 47#include <linux/memory.h>
 48
 
 49#include <asm/debugreg.h>
 50#include <asm/apicdef.h>
 51#include <asm/apic.h>
 52#include <asm/nmi.h>
 
 53
 54struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 55{
 56#ifdef CONFIG_X86_32
 57	{ "ax", 4, offsetof(struct pt_regs, ax) },
 58	{ "cx", 4, offsetof(struct pt_regs, cx) },
 59	{ "dx", 4, offsetof(struct pt_regs, dx) },
 60	{ "bx", 4, offsetof(struct pt_regs, bx) },
 61	{ "sp", 4, offsetof(struct pt_regs, sp) },
 62	{ "bp", 4, offsetof(struct pt_regs, bp) },
 63	{ "si", 4, offsetof(struct pt_regs, si) },
 64	{ "di", 4, offsetof(struct pt_regs, di) },
 65	{ "ip", 4, offsetof(struct pt_regs, ip) },
 66	{ "flags", 4, offsetof(struct pt_regs, flags) },
 67	{ "cs", 4, offsetof(struct pt_regs, cs) },
 68	{ "ss", 4, offsetof(struct pt_regs, ss) },
 69	{ "ds", 4, offsetof(struct pt_regs, ds) },
 70	{ "es", 4, offsetof(struct pt_regs, es) },
 71#else
 72	{ "ax", 8, offsetof(struct pt_regs, ax) },
 73	{ "bx", 8, offsetof(struct pt_regs, bx) },
 74	{ "cx", 8, offsetof(struct pt_regs, cx) },
 75	{ "dx", 8, offsetof(struct pt_regs, dx) },
 76	{ "si", 8, offsetof(struct pt_regs, dx) },
 77	{ "di", 8, offsetof(struct pt_regs, di) },
 78	{ "bp", 8, offsetof(struct pt_regs, bp) },
 79	{ "sp", 8, offsetof(struct pt_regs, sp) },
 80	{ "r8", 8, offsetof(struct pt_regs, r8) },
 81	{ "r9", 8, offsetof(struct pt_regs, r9) },
 82	{ "r10", 8, offsetof(struct pt_regs, r10) },
 83	{ "r11", 8, offsetof(struct pt_regs, r11) },
 84	{ "r12", 8, offsetof(struct pt_regs, r12) },
 85	{ "r13", 8, offsetof(struct pt_regs, r13) },
 86	{ "r14", 8, offsetof(struct pt_regs, r14) },
 87	{ "r15", 8, offsetof(struct pt_regs, r15) },
 88	{ "ip", 8, offsetof(struct pt_regs, ip) },
 89	{ "flags", 4, offsetof(struct pt_regs, flags) },
 90	{ "cs", 4, offsetof(struct pt_regs, cs) },
 91	{ "ss", 4, offsetof(struct pt_regs, ss) },
 92	{ "ds", 4, -1 },
 93	{ "es", 4, -1 },
 94#endif
 95	{ "fs", 4, -1 },
 96	{ "gs", 4, -1 },
 97};
 98
 99int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
100{
101	if (
102#ifdef CONFIG_X86_32
103	    regno == GDB_SS || regno == GDB_FS || regno == GDB_GS ||
104#endif
105	    regno == GDB_SP || regno == GDB_ORIG_AX)
106		return 0;
107
108	if (dbg_reg_def[regno].offset != -1)
109		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
110		       dbg_reg_def[regno].size);
111	return 0;
112}
113
114char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
115{
116	if (regno == GDB_ORIG_AX) {
117		memcpy(mem, &regs->orig_ax, sizeof(regs->orig_ax));
118		return "orig_ax";
119	}
120	if (regno >= DBG_MAX_REG_NUM || regno < 0)
121		return NULL;
122
123	if (dbg_reg_def[regno].offset != -1)
124		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
125		       dbg_reg_def[regno].size);
126
127#ifdef CONFIG_X86_32
128	switch (regno) {
129	case GDB_SS:
130		if (!user_mode_vm(regs))
131			*(unsigned long *)mem = __KERNEL_DS;
132		break;
133	case GDB_SP:
134		if (!user_mode_vm(regs))
135			*(unsigned long *)mem = kernel_stack_pointer(regs);
136		break;
137	case GDB_GS:
138	case GDB_FS:
139		*(unsigned long *)mem = 0xFFFF;
140		break;
141	}
142#endif
143	return dbg_reg_def[regno].name;
144}
145
146/**
147 *	sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
148 *	@gdb_regs: A pointer to hold the registers in the order GDB wants.
149 *	@p: The &struct task_struct of the desired process.
150 *
151 *	Convert the register values of the sleeping process in @p to
152 *	the format that GDB expects.
153 *	This function is called when kgdb does not have access to the
154 *	&struct pt_regs and therefore it should fill the gdb registers
155 *	@gdb_regs with what has	been saved in &struct thread_struct
156 *	thread field during switch_to.
157 */
158void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
159{
160#ifndef CONFIG_X86_32
161	u32 *gdb_regs32 = (u32 *)gdb_regs;
162#endif
163	gdb_regs[GDB_AX]	= 0;
164	gdb_regs[GDB_BX]	= 0;
165	gdb_regs[GDB_CX]	= 0;
166	gdb_regs[GDB_DX]	= 0;
167	gdb_regs[GDB_SI]	= 0;
168	gdb_regs[GDB_DI]	= 0;
169	gdb_regs[GDB_BP]	= *(unsigned long *)p->thread.sp;
170#ifdef CONFIG_X86_32
171	gdb_regs[GDB_DS]	= __KERNEL_DS;
172	gdb_regs[GDB_ES]	= __KERNEL_DS;
173	gdb_regs[GDB_PS]	= 0;
174	gdb_regs[GDB_CS]	= __KERNEL_CS;
175	gdb_regs[GDB_PC]	= p->thread.ip;
176	gdb_regs[GDB_SS]	= __KERNEL_DS;
177	gdb_regs[GDB_FS]	= 0xFFFF;
178	gdb_regs[GDB_GS]	= 0xFFFF;
179#else
180	gdb_regs32[GDB_PS]	= *(unsigned long *)(p->thread.sp + 8);
181	gdb_regs32[GDB_CS]	= __KERNEL_CS;
182	gdb_regs32[GDB_SS]	= __KERNEL_DS;
183	gdb_regs[GDB_PC]	= 0;
184	gdb_regs[GDB_R8]	= 0;
185	gdb_regs[GDB_R9]	= 0;
186	gdb_regs[GDB_R10]	= 0;
187	gdb_regs[GDB_R11]	= 0;
188	gdb_regs[GDB_R12]	= 0;
189	gdb_regs[GDB_R13]	= 0;
190	gdb_regs[GDB_R14]	= 0;
191	gdb_regs[GDB_R15]	= 0;
192#endif
 
193	gdb_regs[GDB_SP]	= p->thread.sp;
194}
195
196static struct hw_breakpoint {
197	unsigned		enabled;
198	unsigned long		addr;
199	int			len;
200	int			type;
201	struct perf_event	* __percpu *pev;
202} breakinfo[HBP_NUM];
203
204static unsigned long early_dr7;
205
206static void kgdb_correct_hw_break(void)
207{
208	int breakno;
209
210	for (breakno = 0; breakno < HBP_NUM; breakno++) {
211		struct perf_event *bp;
212		struct arch_hw_breakpoint *info;
213		int val;
214		int cpu = raw_smp_processor_id();
215		if (!breakinfo[breakno].enabled)
216			continue;
217		if (dbg_is_early) {
218			set_debugreg(breakinfo[breakno].addr, breakno);
219			early_dr7 |= encode_dr7(breakno,
220						breakinfo[breakno].len,
221						breakinfo[breakno].type);
222			set_debugreg(early_dr7, 7);
223			continue;
224		}
225		bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
226		info = counter_arch_bp(bp);
227		if (bp->attr.disabled != 1)
228			continue;
229		bp->attr.bp_addr = breakinfo[breakno].addr;
230		bp->attr.bp_len = breakinfo[breakno].len;
231		bp->attr.bp_type = breakinfo[breakno].type;
232		info->address = breakinfo[breakno].addr;
233		info->len = breakinfo[breakno].len;
234		info->type = breakinfo[breakno].type;
235		val = arch_install_hw_breakpoint(bp);
236		if (!val)
237			bp->attr.disabled = 0;
238	}
239	if (!dbg_is_early)
240		hw_breakpoint_restore();
241}
242
243static int hw_break_reserve_slot(int breakno)
244{
245	int cpu;
246	int cnt = 0;
247	struct perf_event **pevent;
248
249	if (dbg_is_early)
250		return 0;
251
252	for_each_online_cpu(cpu) {
253		cnt++;
254		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
255		if (dbg_reserve_bp_slot(*pevent))
256			goto fail;
257	}
258
259	return 0;
260
261fail:
262	for_each_online_cpu(cpu) {
263		cnt--;
264		if (!cnt)
265			break;
266		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
267		dbg_release_bp_slot(*pevent);
268	}
269	return -1;
270}
271
272static int hw_break_release_slot(int breakno)
273{
274	struct perf_event **pevent;
275	int cpu;
276
277	if (dbg_is_early)
278		return 0;
279
280	for_each_online_cpu(cpu) {
281		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
282		if (dbg_release_bp_slot(*pevent))
283			/*
284			 * The debugger is responsible for handing the retry on
285			 * remove failure.
286			 */
287			return -1;
288	}
289	return 0;
290}
291
292static int
293kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
294{
295	int i;
296
297	for (i = 0; i < HBP_NUM; i++)
298		if (breakinfo[i].addr == addr && breakinfo[i].enabled)
299			break;
300	if (i == HBP_NUM)
301		return -1;
302
303	if (hw_break_release_slot(i)) {
304		printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
305		return -1;
306	}
307	breakinfo[i].enabled = 0;
308
309	return 0;
310}
311
312static void kgdb_remove_all_hw_break(void)
313{
314	int i;
315	int cpu = raw_smp_processor_id();
316	struct perf_event *bp;
317
318	for (i = 0; i < HBP_NUM; i++) {
319		if (!breakinfo[i].enabled)
320			continue;
321		bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
322		if (!bp->attr.disabled) {
323			arch_uninstall_hw_breakpoint(bp);
324			bp->attr.disabled = 1;
325			continue;
326		}
327		if (dbg_is_early)
328			early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
329						 breakinfo[i].type);
330		else if (hw_break_release_slot(i))
331			printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
332			       breakinfo[i].addr);
333		breakinfo[i].enabled = 0;
334	}
335}
336
337static int
338kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
339{
340	int i;
341
342	for (i = 0; i < HBP_NUM; i++)
343		if (!breakinfo[i].enabled)
344			break;
345	if (i == HBP_NUM)
346		return -1;
347
348	switch (bptype) {
349	case BP_HARDWARE_BREAKPOINT:
350		len = 1;
351		breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
352		break;
353	case BP_WRITE_WATCHPOINT:
354		breakinfo[i].type = X86_BREAKPOINT_WRITE;
355		break;
356	case BP_ACCESS_WATCHPOINT:
357		breakinfo[i].type = X86_BREAKPOINT_RW;
358		break;
359	default:
360		return -1;
361	}
362	switch (len) {
363	case 1:
364		breakinfo[i].len = X86_BREAKPOINT_LEN_1;
365		break;
366	case 2:
367		breakinfo[i].len = X86_BREAKPOINT_LEN_2;
368		break;
369	case 4:
370		breakinfo[i].len = X86_BREAKPOINT_LEN_4;
371		break;
372#ifdef CONFIG_X86_64
373	case 8:
374		breakinfo[i].len = X86_BREAKPOINT_LEN_8;
375		break;
376#endif
377	default:
378		return -1;
379	}
380	breakinfo[i].addr = addr;
381	if (hw_break_reserve_slot(i)) {
382		breakinfo[i].addr = 0;
383		return -1;
384	}
385	breakinfo[i].enabled = 1;
386
387	return 0;
388}
389
390/**
391 *	kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
392 *	@regs: Current &struct pt_regs.
393 *
394 *	This function will be called if the particular architecture must
395 *	disable hardware debugging while it is processing gdb packets or
396 *	handling exception.
397 */
398static void kgdb_disable_hw_debug(struct pt_regs *regs)
399{
400	int i;
401	int cpu = raw_smp_processor_id();
402	struct perf_event *bp;
403
404	/* Disable hardware debugging while we are in kgdb: */
405	set_debugreg(0UL, 7);
406	for (i = 0; i < HBP_NUM; i++) {
407		if (!breakinfo[i].enabled)
408			continue;
409		if (dbg_is_early) {
410			early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
411						 breakinfo[i].type);
412			continue;
413		}
414		bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
415		if (bp->attr.disabled == 1)
416			continue;
417		arch_uninstall_hw_breakpoint(bp);
418		bp->attr.disabled = 1;
419	}
420}
421
422#ifdef CONFIG_SMP
423/**
424 *	kgdb_roundup_cpus - Get other CPUs into a holding pattern
425 *	@flags: Current IRQ state
426 *
427 *	On SMP systems, we need to get the attention of the other CPUs
428 *	and get them be in a known state.  This should do what is needed
429 *	to get the other CPUs to call kgdb_wait(). Note that on some arches,
430 *	the NMI approach is not used for rounding up all the CPUs. For example,
431 *	in case of MIPS, smp_call_function() is used to roundup CPUs. In
432 *	this case, we have to make sure that interrupts are enabled before
433 *	calling smp_call_function(). The argument to this function is
434 *	the flags that will be used when restoring the interrupts. There is
435 *	local_irq_save() call before kgdb_roundup_cpus().
436 *
437 *	On non-SMP systems, this is not called.
438 */
439void kgdb_roundup_cpus(unsigned long flags)
440{
441	apic->send_IPI_allbutself(APIC_DM_NMI);
442}
443#endif
444
445/**
446 *	kgdb_arch_handle_exception - Handle architecture specific GDB packets.
447 *	@e_vector: The error vector of the exception that happened.
448 *	@signo: The signal number of the exception that happened.
449 *	@err_code: The error code of the exception that happened.
450 *	@remcomInBuffer: The buffer of the packet we have read.
451 *	@remcomOutBuffer: The buffer of %BUFMAX bytes to write a packet into.
452 *	@linux_regs: The &struct pt_regs of the current process.
453 *
454 *	This function MUST handle the 'c' and 's' command packets,
455 *	as well packets to set / remove a hardware breakpoint, if used.
456 *	If there are additional packets which the hardware needs to handle,
457 *	they are handled here.  The code should return -1 if it wants to
458 *	process more packets, and a %0 or %1 if it wants to exit from the
459 *	kgdb callback.
460 */
461int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
462			       char *remcomInBuffer, char *remcomOutBuffer,
463			       struct pt_regs *linux_regs)
464{
465	unsigned long addr;
466	char *ptr;
467
468	switch (remcomInBuffer[0]) {
469	case 'c':
470	case 's':
471		/* try to read optional parameter, pc unchanged if no parm */
472		ptr = &remcomInBuffer[1];
473		if (kgdb_hex2long(&ptr, &addr))
474			linux_regs->ip = addr;
475	case 'D':
476	case 'k':
477		/* clear the trace bit */
478		linux_regs->flags &= ~X86_EFLAGS_TF;
479		atomic_set(&kgdb_cpu_doing_single_step, -1);
480
481		/* set the trace bit if we're stepping */
482		if (remcomInBuffer[0] == 's') {
483			linux_regs->flags |= X86_EFLAGS_TF;
484			atomic_set(&kgdb_cpu_doing_single_step,
485				   raw_smp_processor_id());
486		}
487
488		return 0;
489	}
490
491	/* this means that we do not want to exit from the handler: */
492	return -1;
493}
494
495static inline int
496single_step_cont(struct pt_regs *regs, struct die_args *args)
497{
498	/*
499	 * Single step exception from kernel space to user space so
500	 * eat the exception and continue the process:
501	 */
502	printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
503			"resuming...\n");
504	kgdb_arch_handle_exception(args->trapnr, args->signr,
505				   args->err, "c", "", regs);
506	/*
507	 * Reset the BS bit in dr6 (pointed by args->err) to
508	 * denote completion of processing
509	 */
510	(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
511
512	return NOTIFY_STOP;
513}
514
515static int was_in_debug_nmi[NR_CPUS];
516
517static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs)
518{
 
 
519	switch (cmd) {
520	case NMI_LOCAL:
521		if (atomic_read(&kgdb_active) != -1) {
522			/* KGDB CPU roundup */
523			kgdb_nmicallback(raw_smp_processor_id(), regs);
524			was_in_debug_nmi[raw_smp_processor_id()] = 1;
 
525			touch_nmi_watchdog();
 
526			return NMI_HANDLED;
527		}
528		break;
529
530	case NMI_UNKNOWN:
531		if (was_in_debug_nmi[raw_smp_processor_id()]) {
532			was_in_debug_nmi[raw_smp_processor_id()] = 0;
 
533			return NMI_HANDLED;
534		}
535		break;
536	default:
537		/* do nothing */
538		break;
539	}
540	return NMI_DONE;
541}
542
543static int __kgdb_notify(struct die_args *args, unsigned long cmd)
544{
545	struct pt_regs *regs = args->regs;
546
547	switch (cmd) {
548	case DIE_DEBUG:
549		if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
550			if (user_mode(regs))
551				return single_step_cont(regs, args);
552			break;
553		} else if (test_thread_flag(TIF_SINGLESTEP))
554			/* This means a user thread is single stepping
555			 * a system call which should be ignored
556			 */
557			return NOTIFY_DONE;
558		/* fall through */
559	default:
560		if (user_mode(regs))
561			return NOTIFY_DONE;
562	}
563
564	if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
565		return NOTIFY_DONE;
566
567	/* Must touch watchdog before return to normal operation */
568	touch_nmi_watchdog();
569	return NOTIFY_STOP;
570}
571
572int kgdb_ll_trap(int cmd, const char *str,
573		 struct pt_regs *regs, long err, int trap, int sig)
574{
575	struct die_args args = {
576		.regs	= regs,
577		.str	= str,
578		.err	= err,
579		.trapnr	= trap,
580		.signr	= sig,
581
582	};
583
584	if (!kgdb_io_module_registered)
585		return NOTIFY_DONE;
586
587	return __kgdb_notify(&args, cmd);
588}
589
590static int
591kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
592{
593	unsigned long flags;
594	int ret;
595
596	local_irq_save(flags);
597	ret = __kgdb_notify(ptr, cmd);
598	local_irq_restore(flags);
599
600	return ret;
601}
602
603static struct notifier_block kgdb_notifier = {
604	.notifier_call	= kgdb_notify,
605};
606
607/**
608 *	kgdb_arch_init - Perform any architecture specific initalization.
609 *
610 *	This function will handle the initalization of any architecture
611 *	specific callbacks.
612 */
613int kgdb_arch_init(void)
614{
615	int retval;
616
617	retval = register_die_notifier(&kgdb_notifier);
618	if (retval)
619		goto out;
620
621	retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler,
622					0, "kgdb");
623	if (retval)
624		goto out1;
625
626	retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler,
627					0, "kgdb");
628
629	if (retval)
630		goto out2;
631
632	return retval;
633
634out2:
635	unregister_nmi_handler(NMI_LOCAL, "kgdb");
636out1:
637	unregister_die_notifier(&kgdb_notifier);
638out:
639	return retval;
640}
641
642static void kgdb_hw_overflow_handler(struct perf_event *event,
643		struct perf_sample_data *data, struct pt_regs *regs)
644{
645	struct task_struct *tsk = current;
646	int i;
647
648	for (i = 0; i < 4; i++)
649		if (breakinfo[i].enabled)
650			tsk->thread.debugreg6 |= (DR_TRAP0 << i);
651}
652
653void kgdb_arch_late(void)
654{
655	int i, cpu;
656	struct perf_event_attr attr;
657	struct perf_event **pevent;
658
659	/*
660	 * Pre-allocate the hw breakpoint structions in the non-atomic
661	 * portion of kgdb because this operation requires mutexs to
662	 * complete.
663	 */
664	hw_breakpoint_init(&attr);
665	attr.bp_addr = (unsigned long)kgdb_arch_init;
666	attr.bp_len = HW_BREAKPOINT_LEN_1;
667	attr.bp_type = HW_BREAKPOINT_W;
668	attr.disabled = 1;
669	for (i = 0; i < HBP_NUM; i++) {
670		if (breakinfo[i].pev)
671			continue;
672		breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL);
673		if (IS_ERR((void * __force)breakinfo[i].pev)) {
674			printk(KERN_ERR "kgdb: Could not allocate hw"
675			       "breakpoints\nDisabling the kernel debugger\n");
676			breakinfo[i].pev = NULL;
677			kgdb_arch_exit();
678			return;
679		}
680		for_each_online_cpu(cpu) {
681			pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
682			pevent[0]->hw.sample_period = 1;
683			pevent[0]->overflow_handler = kgdb_hw_overflow_handler;
684			if (pevent[0]->destroy != NULL) {
685				pevent[0]->destroy = NULL;
686				release_bp_slot(*pevent);
687			}
688		}
689	}
690}
691
692/**
693 *	kgdb_arch_exit - Perform any architecture specific uninitalization.
694 *
695 *	This function will handle the uninitalization of any architecture
696 *	specific callbacks, for dynamic registration and unregistration.
697 */
698void kgdb_arch_exit(void)
699{
700	int i;
701	for (i = 0; i < 4; i++) {
702		if (breakinfo[i].pev) {
703			unregister_wide_hw_breakpoint(breakinfo[i].pev);
704			breakinfo[i].pev = NULL;
705		}
706	}
707	unregister_nmi_handler(NMI_UNKNOWN, "kgdb");
708	unregister_nmi_handler(NMI_LOCAL, "kgdb");
709	unregister_die_notifier(&kgdb_notifier);
710}
711
712/**
713 *
714 *	kgdb_skipexception - Bail out of KGDB when we've been triggered.
715 *	@exception: Exception vector number
716 *	@regs: Current &struct pt_regs.
717 *
718 *	On some architectures we need to skip a breakpoint exception when
719 *	it occurs after a breakpoint has been removed.
720 *
721 * Skip an int3 exception when it occurs after a breakpoint has been
722 * removed. Backtrack eip by 1 since the int3 would have caused it to
723 * increment by 1.
724 */
725int kgdb_skipexception(int exception, struct pt_regs *regs)
726{
727	if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
728		regs->ip -= 1;
729		return 1;
730	}
731	return 0;
732}
733
734unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
735{
736	if (exception == 3)
737		return instruction_pointer(regs) - 1;
738	return instruction_pointer(regs);
739}
740
741void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
742{
743	regs->ip = ip;
744}
745
746int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
747{
748	int err;
749	char opc[BREAK_INSTR_SIZE];
750
751	bpt->type = BP_BREAKPOINT;
752	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
753				BREAK_INSTR_SIZE);
754	if (err)
755		return err;
756	err = probe_kernel_write((char *)bpt->bpt_addr,
757				 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
758#ifdef CONFIG_DEBUG_RODATA
759	if (!err)
760		return err;
761	/*
762	 * It is safe to call text_poke() because normal kernel execution
763	 * is stopped on all cores, so long as the text_mutex is not locked.
764	 */
765	if (mutex_is_locked(&text_mutex))
766		return -EBUSY;
767	text_poke((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
768		  BREAK_INSTR_SIZE);
769	err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
770	if (err)
771		return err;
772	if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE))
773		return -EINVAL;
774	bpt->type = BP_POKE_BREAKPOINT;
775#endif /* CONFIG_DEBUG_RODATA */
776	return err;
777}
778
779int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
780{
781#ifdef CONFIG_DEBUG_RODATA
782	int err;
783	char opc[BREAK_INSTR_SIZE];
784
785	if (bpt->type != BP_POKE_BREAKPOINT)
786		goto knl_write;
787	/*
788	 * It is safe to call text_poke() because normal kernel execution
789	 * is stopped on all cores, so long as the text_mutex is not locked.
790	 */
791	if (mutex_is_locked(&text_mutex))
792		goto knl_write;
793	text_poke((void *)bpt->bpt_addr, bpt->saved_instr, BREAK_INSTR_SIZE);
794	err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
795	if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
796		goto knl_write;
797	return err;
 
798knl_write:
799#endif /* CONFIG_DEBUG_RODATA */
800	return probe_kernel_write((char *)bpt->bpt_addr,
801				  (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
802}
803
804struct kgdb_arch arch_kgdb_ops = {
805	/* Breakpoint instruction: */
806	.gdb_bpt_instr		= { 0xcc },
807	.flags			= KGDB_HW_BREAKPOINT,
808	.set_hw_breakpoint	= kgdb_set_hw_break,
809	.remove_hw_breakpoint	= kgdb_remove_hw_break,
810	.disable_hw_break	= kgdb_disable_hw_debug,
811	.remove_all_hw_break	= kgdb_remove_all_hw_break,
812	.correct_hw_break	= kgdb_correct_hw_break,
813};