Initial import

1 files changed, 814 insertions, 0 deletions

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
new file mode 100644
index 000000000..d6178d979
--- /dev/null
+++ b/arch/x86/kernel/kgdb.c
@@ -0,0 +1,814 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ */
+
+/*
+ * Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com>
+ * Copyright (C) 2000-2001 VERITAS Software Corporation.
+ * Copyright (C) 2002 Andi Kleen, SuSE Labs
+ * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd.
+ * Copyright (C) 2007 MontaVista Software, Inc.
+ * Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc.
+ */
+/****************************************************************************
+ *  Contributor:     Lake Stevens Instrument Division$
+ *  Written by:      Glenn Engel $
+ *  Updated by:	     Amit Kale<akale@veritas.com>
+ *  Updated by:	     Tom Rini <trini@kernel.crashing.org>
+ *  Updated by:	     Jason Wessel <jason.wessel@windriver.com>
+ *  Modified for 386 by Jim Kingdon, Cygnus Support.
+ *  Origianl kgdb, compatibility with 2.1.xx kernel by
+ *  David Grothe <dave@gcom.com>
+ *  Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com>
+ *  X86_64 changes from Andi Kleen's patch merged by Jim Houston
+ */
+#include <linux/spinlock.h>
+#include <linux/kdebug.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/ptrace.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/kgdb.h>
+#include <linux/smp.h>
+#include <linux/nmi.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/uaccess.h>
+#include <linux/memory.h>
+
+#include <asm/debugreg.h>
+#include <asm/apicdef.h>
+#include <asm/apic.h>
+#include <asm/nmi.h>
+
+struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
+{
+#ifdef CONFIG_X86_32
+	{ "ax", 4, offsetof(struct pt_regs, ax) },
+	{ "cx", 4, offsetof(struct pt_regs, cx) },
+	{ "dx", 4, offsetof(struct pt_regs, dx) },
+	{ "bx", 4, offsetof(struct pt_regs, bx) },
+	{ "sp", 4, offsetof(struct pt_regs, sp) },
+	{ "bp", 4, offsetof(struct pt_regs, bp) },
+	{ "si", 4, offsetof(struct pt_regs, si) },
+	{ "di", 4, offsetof(struct pt_regs, di) },
+	{ "ip", 4, offsetof(struct pt_regs, ip) },
+	{ "flags", 4, offsetof(struct pt_regs, flags) },
+	{ "cs", 4, offsetof(struct pt_regs, cs) },
+	{ "ss", 4, offsetof(struct pt_regs, ss) },
+	{ "ds", 4, offsetof(struct pt_regs, ds) },
+	{ "es", 4, offsetof(struct pt_regs, es) },
+#else
+	{ "ax", 8, offsetof(struct pt_regs, ax) },
+	{ "bx", 8, offsetof(struct pt_regs, bx) },
+	{ "cx", 8, offsetof(struct pt_regs, cx) },
+	{ "dx", 8, offsetof(struct pt_regs, dx) },
+	{ "si", 8, offsetof(struct pt_regs, si) },
+	{ "di", 8, offsetof(struct pt_regs, di) },
+	{ "bp", 8, offsetof(struct pt_regs, bp) },
+	{ "sp", 8, offsetof(struct pt_regs, sp) },
+	{ "r8", 8, offsetof(struct pt_regs, r8) },
+	{ "r9", 8, offsetof(struct pt_regs, r9) },
+	{ "r10", 8, offsetof(struct pt_regs, r10) },
+	{ "r11", 8, offsetof(struct pt_regs, r11) },
+	{ "r12", 8, offsetof(struct pt_regs, r12) },
+	{ "r13", 8, offsetof(struct pt_regs, r13) },
+	{ "r14", 8, offsetof(struct pt_regs, r14) },
+	{ "r15", 8, offsetof(struct pt_regs, r15) },
+	{ "ip", 8, offsetof(struct pt_regs, ip) },
+	{ "flags", 4, offsetof(struct pt_regs, flags) },
+	{ "cs", 4, offsetof(struct pt_regs, cs) },
+	{ "ss", 4, offsetof(struct pt_regs, ss) },
+	{ "ds", 4, -1 },
+	{ "es", 4, -1 },
+#endif
+	{ "fs", 4, -1 },
+	{ "gs", 4, -1 },
+};
+
+int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (
+#ifdef CONFIG_X86_32
+	    regno == GDB_SS || regno == GDB_FS || regno == GDB_GS ||
+#endif
+	    regno == GDB_SP || regno == GDB_ORIG_AX)
+		return 0;
+
+	if (dbg_reg_def[regno].offset != -1)
+		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
+		       dbg_reg_def[regno].size);
+	return 0;
+}
+
+char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (regno == GDB_ORIG_AX) {
+		memcpy(mem, &regs->orig_ax, sizeof(regs->orig_ax));
+		return "orig_ax";
+	}
+	if (regno >= DBG_MAX_REG_NUM || regno < 0)
+		return NULL;
+
+	if (dbg_reg_def[regno].offset != -1)
+		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
+		       dbg_reg_def[regno].size);
+
+#ifdef CONFIG_X86_32
+	switch (regno) {
+	case GDB_SS:
+		if (!user_mode(regs))
+			*(unsigned long *)mem = __KERNEL_DS;
+		break;
+	case GDB_SP:
+		if (!user_mode(regs))
+			*(unsigned long *)mem = kernel_stack_pointer(regs);
+		break;
+	case GDB_GS:
+	case GDB_FS:
+		*(unsigned long *)mem = 0xFFFF;
+		break;
+	}
+#endif
+	return dbg_reg_def[regno].name;
+}
+
+/**
+ *	sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
+ *	@gdb_regs: A pointer to hold the registers in the order GDB wants.
+ *	@p: The &struct task_struct of the desired process.
+ *
+ *	Convert the register values of the sleeping process in @p to
+ *	the format that GDB expects.
+ *	This function is called when kgdb does not have access to the
+ *	&struct pt_regs and therefore it should fill the gdb registers
+ *	@gdb_regs with what has	been saved in &struct thread_struct
+ *	thread field during switch_to.
+ */
+void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
+{
+#ifndef CONFIG_X86_32
+	u32 *gdb_regs32 = (u32 *)gdb_regs;
+#endif
+	gdb_regs[GDB_AX]	= 0;
+	gdb_regs[GDB_BX]	= 0;
+	gdb_regs[GDB_CX]	= 0;
+	gdb_regs[GDB_DX]	= 0;
+	gdb_regs[GDB_SI]	= 0;
+	gdb_regs[GDB_DI]	= 0;
+	gdb_regs[GDB_BP]	= *(unsigned long *)p->thread.sp;
+#ifdef CONFIG_X86_32
+	gdb_regs[GDB_DS]	= __KERNEL_DS;
+	gdb_regs[GDB_ES]	= __KERNEL_DS;
+	gdb_regs[GDB_PS]	= 0;
+	gdb_regs[GDB_CS]	= __KERNEL_CS;
+	gdb_regs[GDB_PC]	= p->thread.ip;
+	gdb_regs[GDB_SS]	= __KERNEL_DS;
+	gdb_regs[GDB_FS]	= 0xFFFF;
+	gdb_regs[GDB_GS]	= 0xFFFF;
+#else
+	gdb_regs32[GDB_PS]	= *(unsigned long *)(p->thread.sp + 8);
+	gdb_regs32[GDB_CS]	= __KERNEL_CS;
+	gdb_regs32[GDB_SS]	= __KERNEL_DS;
+	gdb_regs[GDB_PC]	= 0;
+	gdb_regs[GDB_R8]	= 0;
+	gdb_regs[GDB_R9]	= 0;
+	gdb_regs[GDB_R10]	= 0;
+	gdb_regs[GDB_R11]	= 0;
+	gdb_regs[GDB_R12]	= 0;
+	gdb_regs[GDB_R13]	= 0;
+	gdb_regs[GDB_R14]	= 0;
+	gdb_regs[GDB_R15]	= 0;
+#endif
+	gdb_regs[GDB_SP]	= p->thread.sp;
+}
+
+static struct hw_breakpoint {
+	unsigned		enabled;
+	unsigned long		addr;
+	int			len;
+	int			type;
+	struct perf_event	* __percpu *pev;
+} breakinfo[HBP_NUM];
+
+static unsigned long early_dr7;
+
+static void kgdb_correct_hw_break(void)
+{
+	int breakno;
+
+	for (breakno = 0; breakno < HBP_NUM; breakno++) {
+		struct perf_event *bp;
+		struct arch_hw_breakpoint *info;
+		int val;
+		int cpu = raw_smp_processor_id();
+		if (!breakinfo[breakno].enabled)
+			continue;
+		if (dbg_is_early) {
+			set_debugreg(breakinfo[breakno].addr, breakno);
+			early_dr7 |= encode_dr7(breakno,
+						breakinfo[breakno].len,
+						breakinfo[breakno].type);
+			set_debugreg(early_dr7, 7);
+			continue;
+		}
+		bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
+		info = counter_arch_bp(bp);
+		if (bp->attr.disabled != 1)
+			continue;
+		bp->attr.bp_addr = breakinfo[breakno].addr;
+		bp->attr.bp_len = breakinfo[breakno].len;
+		bp->attr.bp_type = breakinfo[breakno].type;
+		info->address = breakinfo[breakno].addr;
+		info->len = breakinfo[breakno].len;
+		info->type = breakinfo[breakno].type;
+		val = arch_install_hw_breakpoint(bp);
+		if (!val)
+			bp->attr.disabled = 0;
+	}
+	if (!dbg_is_early)
+		hw_breakpoint_restore();
+}
+
+static int hw_break_reserve_slot(int breakno)
+{
+	int cpu;
+	int cnt = 0;
+	struct perf_event **pevent;
+
+	if (dbg_is_early)
+		return 0;
+
+	for_each_online_cpu(cpu) {
+		cnt++;
+		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+		if (dbg_reserve_bp_slot(*pevent))
+			goto fail;
+	}
+
+	return 0;
+
+fail:
+	for_each_online_cpu(cpu) {
+		cnt--;
+		if (!cnt)
+			break;
+		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+		dbg_release_bp_slot(*pevent);
+	}
+	return -1;
+}
+
+static int hw_break_release_slot(int breakno)
+{
+	struct perf_event **pevent;
+	int cpu;
+
+	if (dbg_is_early)
+		return 0;
+
+	for_each_online_cpu(cpu) {
+		pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
+		if (dbg_release_bp_slot(*pevent))
+			/*
+			 * The debugger is responsible for handing the retry on
+			 * remove failure.
+			 */
+			return -1;
+	}
+	return 0;
+}
+
+static int
+kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
+{
+	int i;
+
+	for (i = 0; i < HBP_NUM; i++)
+		if (breakinfo[i].addr == addr && breakinfo[i].enabled)
+			break;
+	if (i == HBP_NUM)
+		return -1;
+
+	if (hw_break_release_slot(i)) {
+		printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
+		return -1;
+	}
+	breakinfo[i].enabled = 0;
+
+	return 0;
+}
+
+static void kgdb_remove_all_hw_break(void)
+{
+	int i;
+	int cpu = raw_smp_processor_id();
+	struct perf_event *bp;
+
+	for (i = 0; i < HBP_NUM; i++) {
+		if (!breakinfo[i].enabled)
+			continue;
+		bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
+		if (!bp->attr.disabled) {
+			arch_uninstall_hw_breakpoint(bp);
+			bp->attr.disabled = 1;
+			continue;
+		}
+		if (dbg_is_early)
+			early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
+						 breakinfo[i].type);
+		else if (hw_break_release_slot(i))
+			printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
+			       breakinfo[i].addr);
+		breakinfo[i].enabled = 0;
+	}
+}
+
+static int
+kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
+{
+	int i;
+
+	for (i = 0; i < HBP_NUM; i++)
+		if (!breakinfo[i].enabled)
+			break;
+	if (i == HBP_NUM)
+		return -1;
+
+	switch (bptype) {
+	case BP_HARDWARE_BREAKPOINT:
+		len = 1;
+		breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
+		break;
+	case BP_WRITE_WATCHPOINT:
+		breakinfo[i].type = X86_BREAKPOINT_WRITE;
+		break;
+	case BP_ACCESS_WATCHPOINT:
+		breakinfo[i].type = X86_BREAKPOINT_RW;
+		break;
+	default:
+		return -1;
+	}
+	switch (len) {
+	case 1:
+		breakinfo[i].len = X86_BREAKPOINT_LEN_1;
+		break;
+	case 2:
+		breakinfo[i].len = X86_BREAKPOINT_LEN_2;
+		break;
+	case 4:
+		breakinfo[i].len = X86_BREAKPOINT_LEN_4;
+		break;
+#ifdef CONFIG_X86_64
+	case 8:
+		breakinfo[i].len = X86_BREAKPOINT_LEN_8;
+		break;
+#endif
+	default:
+		return -1;
+	}
+	breakinfo[i].addr = addr;
+	if (hw_break_reserve_slot(i)) {
+		breakinfo[i].addr = 0;
+		return -1;
+	}
+	breakinfo[i].enabled = 1;
+
+	return 0;
+}
+
+/**
+ *	kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
+ *	@regs: Current &struct pt_regs.
+ *
+ *	This function will be called if the particular architecture must
+ *	disable hardware debugging while it is processing gdb packets or
+ *	handling exception.
+ */
+static void kgdb_disable_hw_debug(struct pt_regs *regs)
+{
+	int i;
+	int cpu = raw_smp_processor_id();
+	struct perf_event *bp;
+
+	/* Disable hardware debugging while we are in kgdb: */
+	set_debugreg(0UL, 7);
+	for (i = 0; i < HBP_NUM; i++) {
+		if (!breakinfo[i].enabled)
+			continue;
+		if (dbg_is_early) {
+			early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
+						 breakinfo[i].type);
+			continue;
+		}
+		bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
+		if (bp->attr.disabled == 1)
+			continue;
+		arch_uninstall_hw_breakpoint(bp);
+		bp->attr.disabled = 1;
+	}
+}
+
+#ifdef CONFIG_SMP
+/**
+ *	kgdb_roundup_cpus - Get other CPUs into a holding pattern
+ *	@flags: Current IRQ state
+ *
+ *	On SMP systems, we need to get the attention of the other CPUs
+ *	and get them be in a known state.  This should do what is needed
+ *	to get the other CPUs to call kgdb_wait(). Note that on some arches,
+ *	the NMI approach is not used for rounding up all the CPUs. For example,
+ *	in case of MIPS, smp_call_function() is used to roundup CPUs. In
+ *	this case, we have to make sure that interrupts are enabled before
+ *	calling smp_call_function(). The argument to this function is
+ *	the flags that will be used when restoring the interrupts. There is
+ *	local_irq_save() call before kgdb_roundup_cpus().
+ *
+ *	On non-SMP systems, this is not called.
+ */
+void kgdb_roundup_cpus(unsigned long flags)
+{
+	apic->send_IPI_allbutself(APIC_DM_NMI);
+}
+#endif
+
+/**
+ *	kgdb_arch_handle_exception - Handle architecture specific GDB packets.
+ *	@e_vector: The error vector of the exception that happened.
+ *	@signo: The signal number of the exception that happened.
+ *	@err_code: The error code of the exception that happened.
+ *	@remcomInBuffer: The buffer of the packet we have read.
+ *	@remcomOutBuffer: The buffer of %BUFMAX bytes to write a packet into.
+ *	@linux_regs: The &struct pt_regs of the current process.
+ *
+ *	This function MUST handle the 'c' and 's' command packets,
+ *	as well packets to set / remove a hardware breakpoint, if used.
+ *	If there are additional packets which the hardware needs to handle,
+ *	they are handled here.  The code should return -1 if it wants to
+ *	process more packets, and a %0 or %1 if it wants to exit from the
+ *	kgdb callback.
+ */
+int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
+			       char *remcomInBuffer, char *remcomOutBuffer,
+			       struct pt_regs *linux_regs)
+{
+	unsigned long addr;
+	char *ptr;
+
+	switch (remcomInBuffer[0]) {
+	case 'c':
+	case 's':
+		/* try to read optional parameter, pc unchanged if no parm */
+		ptr = &remcomInBuffer[1];
+		if (kgdb_hex2long(&ptr, &addr))
+			linux_regs->ip = addr;
+	case 'D':
+	case 'k':
+		/* clear the trace bit */
+		linux_regs->flags &= ~X86_EFLAGS_TF;
+		atomic_set(&kgdb_cpu_doing_single_step, -1);
+
+		/* set the trace bit if we're stepping */
+		if (remcomInBuffer[0] == 's') {
+			linux_regs->flags |= X86_EFLAGS_TF;
+			atomic_set(&kgdb_cpu_doing_single_step,
+				   raw_smp_processor_id());
+		}
+
+		return 0;
+	}
+
+	/* this means that we do not want to exit from the handler: */
+	return -1;
+}
+
+static inline int
+single_step_cont(struct pt_regs *regs, struct die_args *args)
+{
+	/*
+	 * Single step exception from kernel space to user space so
+	 * eat the exception and continue the process:
+	 */
+	printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
+			"resuming...\n");
+	kgdb_arch_handle_exception(args->trapnr, args->signr,
+				   args->err, "c", "", regs);
+	/*
+	 * Reset the BS bit in dr6 (pointed by args->err) to
+	 * denote completion of processing
+	 */
+	(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
+
+	return NOTIFY_STOP;
+}
+
+static int was_in_debug_nmi[NR_CPUS];
+
+static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs)
+{
+	switch (cmd) {
+	case NMI_LOCAL:
+		if (atomic_read(&kgdb_active) != -1) {
+			/* KGDB CPU roundup */
+			kgdb_nmicallback(raw_smp_processor_id(), regs);
+			was_in_debug_nmi[raw_smp_processor_id()] = 1;
+			touch_nmi_watchdog();
+			return NMI_HANDLED;
+		}
+		break;
+
+	case NMI_UNKNOWN:
+		if (was_in_debug_nmi[raw_smp_processor_id()]) {
+			was_in_debug_nmi[raw_smp_processor_id()] = 0;
+			return NMI_HANDLED;
+		}
+		break;
+	default:
+		/* do nothing */
+		break;
+	}
+	return NMI_DONE;
+}
+
+static int __kgdb_notify(struct die_args *args, unsigned long cmd)
+{
+	struct pt_regs *regs = args->regs;
+
+	switch (cmd) {
+	case DIE_DEBUG:
+		if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
+			if (user_mode(regs))
+				return single_step_cont(regs, args);
+			break;
+		} else if (test_thread_flag(TIF_SINGLESTEP))
+			/* This means a user thread is single stepping
+			 * a system call which should be ignored
+			 */
+			return NOTIFY_DONE;
+		/* fall through */
+	default:
+		if (user_mode(regs))
+			return NOTIFY_DONE;
+	}
+
+	if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
+		return NOTIFY_DONE;
+
+	/* Must touch watchdog before return to normal operation */
+	touch_nmi_watchdog();
+	return NOTIFY_STOP;
+}
+
+int kgdb_ll_trap(int cmd, const char *str,
+		 struct pt_regs *regs, long err, int trap, int sig)
+{
+	struct die_args args = {
+		.regs	= regs,
+		.str	= str,
+		.err	= err,
+		.trapnr	= trap,
+		.signr	= sig,
+
+	};
+
+	if (!kgdb_io_module_registered)
+		return NOTIFY_DONE;
+
+	return __kgdb_notify(&args, cmd);
+}
+
+static int
+kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
+{
+	unsigned long flags;
+	int ret;
+
+	local_irq_save(flags);
+	ret = __kgdb_notify(ptr, cmd);
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+static struct notifier_block kgdb_notifier = {
+	.notifier_call	= kgdb_notify,
+};
+
+/**
+ *	kgdb_arch_init - Perform any architecture specific initalization.
+ *
+ *	This function will handle the initalization of any architecture
+ *	specific callbacks.
+ */
+int kgdb_arch_init(void)
+{
+	int retval;
+
+	retval = register_die_notifier(&kgdb_notifier);
+	if (retval)
+		goto out;
+
+	retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler,
+					0, "kgdb");
+	if (retval)
+		goto out1;
+
+	retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler,
+					0, "kgdb");
+
+	if (retval)
+		goto out2;
+
+	return retval;
+
+out2:
+	unregister_nmi_handler(NMI_LOCAL, "kgdb");
+out1:
+	unregister_die_notifier(&kgdb_notifier);
+out:
+	return retval;
+}
+
+static void kgdb_hw_overflow_handler(struct perf_event *event,
+		struct perf_sample_data *data, struct pt_regs *regs)
+{
+	struct task_struct *tsk = current;
+	int i;
+
+	for (i = 0; i < 4; i++)
+		if (breakinfo[i].enabled)
+			tsk->thread.debugreg6 |= (DR_TRAP0 << i);
+}
+
+void kgdb_arch_late(void)
+{
+	int i, cpu;
+	struct perf_event_attr attr;
+	struct perf_event **pevent;
+
+	/*
+	 * Pre-allocate the hw breakpoint structions in the non-atomic
+	 * portion of kgdb because this operation requires mutexs to
+	 * complete.
+	 */
+	hw_breakpoint_init(&attr);
+	attr.bp_addr = (unsigned long)kgdb_arch_init;
+	attr.bp_len = HW_BREAKPOINT_LEN_1;
+	attr.bp_type = HW_BREAKPOINT_W;
+	attr.disabled = 1;
+	for (i = 0; i < HBP_NUM; i++) {
+		if (breakinfo[i].pev)
+			continue;
+		breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL);
+		if (IS_ERR((void * __force)breakinfo[i].pev)) {
+			printk(KERN_ERR "kgdb: Could not allocate hw"
+			       "breakpoints\nDisabling the kernel debugger\n");
+			breakinfo[i].pev = NULL;
+			kgdb_arch_exit();
+			return;
+		}
+		for_each_online_cpu(cpu) {
+			pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
+			pevent[0]->hw.sample_period = 1;
+			pevent[0]->overflow_handler = kgdb_hw_overflow_handler;
+			if (pevent[0]->destroy != NULL) {
+				pevent[0]->destroy = NULL;
+				release_bp_slot(*pevent);
+			}
+		}
+	}
+}
+
+/**
+ *	kgdb_arch_exit - Perform any architecture specific uninitalization.
+ *
+ *	This function will handle the uninitalization of any architecture
+ *	specific callbacks, for dynamic registration and unregistration.
+ */
+void kgdb_arch_exit(void)
+{
+	int i;
+	for (i = 0; i < 4; i++) {
+		if (breakinfo[i].pev) {
+			unregister_wide_hw_breakpoint(breakinfo[i].pev);
+			breakinfo[i].pev = NULL;
+		}
+	}
+	unregister_nmi_handler(NMI_UNKNOWN, "kgdb");
+	unregister_nmi_handler(NMI_LOCAL, "kgdb");
+	unregister_die_notifier(&kgdb_notifier);
+}
+
+/**
+ *
+ *	kgdb_skipexception - Bail out of KGDB when we've been triggered.
+ *	@exception: Exception vector number
+ *	@regs: Current &struct pt_regs.
+ *
+ *	On some architectures we need to skip a breakpoint exception when
+ *	it occurs after a breakpoint has been removed.
+ *
+ * Skip an int3 exception when it occurs after a breakpoint has been
+ * removed. Backtrack eip by 1 since the int3 would have caused it to
+ * increment by 1.
+ */
+int kgdb_skipexception(int exception, struct pt_regs *regs)
+{
+	if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
+		regs->ip -= 1;
+		return 1;
+	}
+	return 0;
+}
+
+unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
+{
+	if (exception == 3)
+		return instruction_pointer(regs) - 1;
+	return instruction_pointer(regs);
+}
+
+void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
+{
+	regs->ip = ip;
+}
+
+int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
+{
+	int err;
+#ifdef CONFIG_DEBUG_RODATA
+	char opc[BREAK_INSTR_SIZE];
+#endif /* CONFIG_DEBUG_RODATA */
+
+	bpt->type = BP_BREAKPOINT;
+	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+				BREAK_INSTR_SIZE);
+	if (err)
+		return err;
+	err = probe_kernel_write((char *)bpt->bpt_addr,
+				 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
+#ifdef CONFIG_DEBUG_RODATA
+	if (!err)
+		return err;
+	/*
+	 * It is safe to call text_poke() because normal kernel execution
+	 * is stopped on all cores, so long as the text_mutex is not locked.
+	 */
+	if (mutex_is_locked(&text_mutex))
+		return -EBUSY;
+	text_poke((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
+		  BREAK_INSTR_SIZE);
+	err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
+	if (err)
+		return err;
+	if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE))
+		return -EINVAL;
+	bpt->type = BP_POKE_BREAKPOINT;
+#endif /* CONFIG_DEBUG_RODATA */
+	return err;
+}
+
+int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
+{
+#ifdef CONFIG_DEBUG_RODATA
+	int err;
+	char opc[BREAK_INSTR_SIZE];
+
+	if (bpt->type != BP_POKE_BREAKPOINT)
+		goto knl_write;
+	/*
+	 * It is safe to call text_poke() because normal kernel execution
+	 * is stopped on all cores, so long as the text_mutex is not locked.
+	 */
+	if (mutex_is_locked(&text_mutex))
+		goto knl_write;
+	text_poke((void *)bpt->bpt_addr, bpt->saved_instr, BREAK_INSTR_SIZE);
+	err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
+	if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
+		goto knl_write;
+	return err;
+knl_write:
+#endif /* CONFIG_DEBUG_RODATA */
+	return probe_kernel_write((char *)bpt->bpt_addr,
+				  (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
+}
+
+struct kgdb_arch arch_kgdb_ops = {
+	/* Breakpoint instruction: */
+	.gdb_bpt_instr		= { 0xcc },
+	.flags			= KGDB_HW_BREAKPOINT,
+	.set_hw_breakpoint	= kgdb_set_hw_break,
+	.remove_hw_breakpoint	= kgdb_remove_hw_break,
+	.disable_hw_break	= kgdb_disable_hw_debug,
+	.remove_all_hw_break	= kgdb_remove_all_hw_break,
+	.correct_hw_break	= kgdb_correct_hw_break,
+};