arch/x86/kernel/kgdb.c - arm/linux-arm64-legacy - Git at Google

 /*
  * 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/init.h>
 #include <linux/smp.h>
 #include <linux/nmi.h>

 #include <asm/apicdef.h>
 #include <asm/system.h>

 #include <asm/apic.h>

 /*
  * Put the error code here just in case the user cares:
  */
 static int gdb_x86errcode;

 /*
  * Likewise, the vector number here (since GDB only gets the signal
  * number through the usual means, and that's not very specific):
  */
 static int gdb_x86vector = -1;

 /**
  *	pt_regs_to_gdb_regs - Convert ptrace regs to GDB regs
  *	@gdb_regs: A pointer to hold the registers in the order GDB wants.
  *	@regs: The &struct pt_regs of the current process.
  *
  *	Convert the pt_regs in @regs into the format for registers that
  *	GDB expects, stored in @gdb_regs.
  */
 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 {
 #ifndef CONFIG_X86_32
 	u32 *gdb_regs32 = (u32 *)gdb_regs;
 #endif
 	gdb_regs[GDB_AX]	= regs->ax;
 	gdb_regs[GDB_BX]	= regs->bx;
 	gdb_regs[GDB_CX]	= regs->cx;
 	gdb_regs[GDB_DX]	= regs->dx;
 	gdb_regs[GDB_SI]	= regs->si;
 	gdb_regs[GDB_DI]	= regs->di;
 	gdb_regs[GDB_BP]	= regs->bp;
 	gdb_regs[GDB_PC]	= regs->ip;
 #ifdef CONFIG_X86_32
 	gdb_regs[GDB_PS]	= regs->flags;
 	gdb_regs[GDB_DS]	= regs->ds;
 	gdb_regs[GDB_ES]	= regs->es;
 	gdb_regs[GDB_CS]	= regs->cs;
 	gdb_regs[GDB_SS]	= __KERNEL_DS;
 	gdb_regs[GDB_FS]	= 0xFFFF;
 	gdb_regs[GDB_GS]	= 0xFFFF;
 	gdb_regs[GDB_SP]	= (int)&regs->sp;
 #else
 	gdb_regs[GDB_R8]	= regs->r8;
 	gdb_regs[GDB_R9]	= regs->r9;
 	gdb_regs[GDB_R10]	= regs->r10;
 	gdb_regs[GDB_R11]	= regs->r11;
 	gdb_regs[GDB_R12]	= regs->r12;
 	gdb_regs[GDB_R13]	= regs->r13;
 	gdb_regs[GDB_R14]	= regs->r14;
 	gdb_regs[GDB_R15]	= regs->r15;
 	gdb_regs32[GDB_PS]	= regs->flags;
 	gdb_regs32[GDB_CS]	= regs->cs;
 	gdb_regs32[GDB_SS]	= regs->ss;
 	gdb_regs[GDB_SP]	= regs->sp;
 #endif
 }

 /**
  *	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]	= p->thread.ip;
 	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;
 }

 /**
  *	gdb_regs_to_pt_regs - Convert GDB regs to ptrace regs.
  *	@gdb_regs: A pointer to hold the registers we've received from GDB.
  *	@regs: A pointer to a &struct pt_regs to hold these values in.
  *
  *	Convert the GDB regs in @gdb_regs into the pt_regs, and store them
  *	in @regs.
  */
 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 {
 #ifndef CONFIG_X86_32
 	u32 *gdb_regs32 = (u32 *)gdb_regs;
 #endif
 	regs->ax		= gdb_regs[GDB_AX];
 	regs->bx		= gdb_regs[GDB_BX];
 	regs->cx		= gdb_regs[GDB_CX];
 	regs->dx		= gdb_regs[GDB_DX];
 	regs->si		= gdb_regs[GDB_SI];
 	regs->di		= gdb_regs[GDB_DI];
 	regs->bp		= gdb_regs[GDB_BP];
 	regs->ip		= gdb_regs[GDB_PC];
 #ifdef CONFIG_X86_32
 	regs->flags		= gdb_regs[GDB_PS];
 	regs->ds		= gdb_regs[GDB_DS];
 	regs->es		= gdb_regs[GDB_ES];
 	regs->cs		= gdb_regs[GDB_CS];
 #else
 	regs->r8		= gdb_regs[GDB_R8];
 	regs->r9		= gdb_regs[GDB_R9];
 	regs->r10		= gdb_regs[GDB_R10];
 	regs->r11		= gdb_regs[GDB_R11];
 	regs->r12		= gdb_regs[GDB_R12];
 	regs->r13		= gdb_regs[GDB_R13];
 	regs->r14		= gdb_regs[GDB_R14];
 	regs->r15		= gdb_regs[GDB_R15];
 	regs->flags		= gdb_regs32[GDB_PS];
 	regs->cs		= gdb_regs32[GDB_CS];
 	regs->ss		= gdb_regs32[GDB_SS];
 #endif
 }

 static struct hw_breakpoint {
 	unsigned		enabled;
 	unsigned		type;
 	unsigned		len;
 	unsigned long		addr;
 } breakinfo[4];

 static void kgdb_correct_hw_break(void)
 {
 	unsigned long dr7;
 	int correctit = 0;
 	int breakbit;
 	int breakno;

 	get_debugreg(dr7, 7);
 	for (breakno = 0; breakno < 4; breakno++) {
 		breakbit = 2 << (breakno << 1);
 		if (!(dr7 & breakbit) && breakinfo[breakno].enabled) {
 			correctit = 1;
 			dr7 |= breakbit;
 			dr7 &= ~(0xf0000 << (breakno << 2));
 			dr7 |= ((breakinfo[breakno].len << 2) |
 				 breakinfo[breakno].type) <<
 			       ((breakno << 2) + 16);
 			if (breakno >= 0 && breakno <= 3)
 				set_debugreg(breakinfo[breakno].addr, breakno);

 		} else {
 			if ((dr7 & breakbit) && !breakinfo[breakno].enabled) {
 				correctit = 1;
 				dr7 &= ~breakbit;
 				dr7 &= ~(0xf0000 << (breakno << 2));
 			}
 		}
 	}
 	if (correctit)
 		set_debugreg(dr7, 7);
 }

 static int
 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 {
 	int i;

 	for (i = 0; i < 4; i++)
 		if (breakinfo[i].addr == addr && breakinfo[i].enabled)
 			break;
 	if (i == 4)
 		return -1;

 	breakinfo[i].enabled = 0;

 	return 0;
 }

 static void kgdb_remove_all_hw_break(void)
 {
 	int i;

 	for (i = 0; i < 4; i++)
 		memset(&breakinfo[i], 0, sizeof(struct hw_breakpoint));
 }

 static int
 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 {
 	unsigned type;
 	int i;

 	for (i = 0; i < 4; i++)
 		if (!breakinfo[i].enabled)
 			break;
 	if (i == 4)
 		return -1;

 	switch (bptype) {
 	case BP_HARDWARE_BREAKPOINT:
 		type = 0;
 		len  = 1;
 		break;
 	case BP_WRITE_WATCHPOINT:
 		type = 1;
 		break;
 	case BP_ACCESS_WATCHPOINT:
 		type = 3;
 		break;
 	default:
 		return -1;
 	}

 	if (len == 1 || len == 2 || len == 4)
 		breakinfo[i].len  = len - 1;
 	else
 		return -1;

 	breakinfo[i].enabled = 1;
 	breakinfo[i].addr = addr;
 	breakinfo[i].type = type;

 	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.
  */
 void kgdb_disable_hw_debug(struct pt_regs *regs)
 {
 	/* Disable hardware debugging while we are in kgdb: */
 	set_debugreg(0UL, 7);
 }

 /**
  *	kgdb_post_primary_code - Save error vector/code numbers.
  *	@regs: Original pt_regs.
  *	@e_vector: Original error vector.
  *	@err_code: Original error code.
  *
  *	This is needed on architectures which support SMP and KGDB.
  *	This function is called after all the slave cpus have been put
  *	to a know spin state and the primary CPU has control over KGDB.
  */
 void kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
 {
 	/* primary processor is completely in the debugger */
 	gdb_x86vector = e_vector;
 	gdb_x86errcode = err_code;
 }

 #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.
  *	@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.
  *	@remcom_in_buffer: The buffer of the packet we have read.
  *	@remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
  *	@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;
 	unsigned long dr6;
 	char *ptr;
 	int newPC;

 	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':
 		newPC = linux_regs->ip;

 		/* 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;
 			kgdb_single_step = 1;
 			atomic_set(&kgdb_cpu_doing_single_step,
 				   raw_smp_processor_id());
 		}

 		get_debugreg(dr6, 6);
 		if (!(dr6 & 0x4000)) {
 			int breakno;

 			for (breakno = 0; breakno < 4; breakno++) {
 				if (dr6 & (1 << breakno) &&
 				    breakinfo[breakno].type == 0) {
 					/* Set restore flag: */
 					linux_regs->flags |= X86_EFLAGS_RF;
 					break;
 				}
 			}
 		}
 		set_debugreg(0UL, 6);
 		kgdb_correct_hw_break();

 		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);

 	return NOTIFY_STOP;
 }

 static int was_in_debug_nmi[NR_CPUS];

 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {
 	struct pt_regs *regs = args->regs;

 	switch (cmd) {
 	case DIE_NMI:
 		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 NOTIFY_STOP;
 		}
 		return NOTIFY_DONE;

 	case DIE_NMI_IPI:
 		/* Just ignore, we will handle the roundup on DIE_NMI. */
 		return NOTIFY_DONE;

 	case DIE_NMIUNKNOWN:
 		if (was_in_debug_nmi[raw_smp_processor_id()]) {
 			was_in_debug_nmi[raw_smp_processor_id()] = 0;
 			return NOTIFY_STOP;
 		}
 		return NOTIFY_DONE;

 	case DIE_NMIWATCHDOG:
 		if (atomic_read(&kgdb_active) != -1) {
 			/* KGDB CPU roundup: */
 			kgdb_nmicallback(raw_smp_processor_id(), regs);
 			return NOTIFY_STOP;
 		}
 		/* Enter debugger: */
 		break;

 	case DIE_DEBUG:
 		if (atomic_read(&kgdb_cpu_doing_single_step) ==
 		    raw_smp_processor_id()) {
 			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, args->err, regs))
 		return NOTIFY_DONE;

 	/* Must touch watchdog before return to normal operation */
 	touch_nmi_watchdog();
 	return NOTIFY_STOP;
 }

 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,

 	/*
 	 * Lowest-prio notifier priority, we want to be notified last:
 	 */
 	.priority	= -INT_MAX,
 };

 /**
  *	kgdb_arch_init - Perform any architecture specific initalization.
  *
  *	This function will handle the initalization of any architecture
  *	specific callbacks.
  */
 int kgdb_arch_init(void)
 {
 	return register_die_notifier(&kgdb_notifier);
 }

 /**
  *	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)
 {
 	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);
 }

 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,
 	.remove_all_hw_break	= kgdb_remove_all_hw_break,
 	.correct_hw_break	= kgdb_correct_hw_break,
 };
	/*
	* 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/init.h>
	#include <linux/smp.h>
	#include <linux/nmi.h>

	#include <asm/apicdef.h>
	#include <asm/system.h>

	#include <asm/apic.h>

	/*
	* Put the error code here just in case the user cares:
	*/
	static int gdb_x86errcode;

	/*
	* Likewise, the vector number here (since GDB only gets the signal
	* number through the usual means, and that's not very specific):
	*/
	static int gdb_x86vector = -1;

	/**
	* pt_regs_to_gdb_regs - Convert ptrace regs to GDB regs
	* @gdb_regs: A pointer to hold the registers in the order GDB wants.
	* @regs: The &struct pt_regs of the current process.
	*
	* Convert the pt_regs in @regs into the format for registers that
	* GDB expects, stored in @gdb_regs.
	*/
	void pt_regs_to_gdb_regs(unsigned long gdb_regs, struct pt_regs regs)
	{
	#ifndef CONFIG_X86_32
	u32 gdb_regs32 = (u32 )gdb_regs;
	#endif
	gdb_regs[GDB_AX] = regs->ax;
	gdb_regs[GDB_BX] = regs->bx;
	gdb_regs[GDB_CX] = regs->cx;
	gdb_regs[GDB_DX] = regs->dx;
	gdb_regs[GDB_SI] = regs->si;
	gdb_regs[GDB_DI] = regs->di;
	gdb_regs[GDB_BP] = regs->bp;
	gdb_regs[GDB_PC] = regs->ip;
	#ifdef CONFIG_X86_32
	gdb_regs[GDB_PS] = regs->flags;
	gdb_regs[GDB_DS] = regs->ds;
	gdb_regs[GDB_ES] = regs->es;
	gdb_regs[GDB_CS] = regs->cs;
	gdb_regs[GDB_SS] = __KERNEL_DS;
	gdb_regs[GDB_FS] = 0xFFFF;
	gdb_regs[GDB_GS] = 0xFFFF;
	gdb_regs[GDB_SP] = (int)&regs->sp;
	#else
	gdb_regs[GDB_R8] = regs->r8;
	gdb_regs[GDB_R9] = regs->r9;
	gdb_regs[GDB_R10] = regs->r10;
	gdb_regs[GDB_R11] = regs->r11;
	gdb_regs[GDB_R12] = regs->r12;
	gdb_regs[GDB_R13] = regs->r13;
	gdb_regs[GDB_R14] = regs->r14;
	gdb_regs[GDB_R15] = regs->r15;
	gdb_regs32[GDB_PS] = regs->flags;
	gdb_regs32[GDB_CS] = regs->cs;
	gdb_regs32[GDB_SS] = regs->ss;
	gdb_regs[GDB_SP] = regs->sp;
	#endif
	}

	/**
	* 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] = p->thread.ip;
	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;
	}

	/**
	* gdb_regs_to_pt_regs - Convert GDB regs to ptrace regs.
	* @gdb_regs: A pointer to hold the registers we've received from GDB.
	* @regs: A pointer to a &struct pt_regs to hold these values in.
	*
	* Convert the GDB regs in @gdb_regs into the pt_regs, and store them
	* in @regs.
	*/
	void gdb_regs_to_pt_regs(unsigned long gdb_regs, struct pt_regs regs)
	{
	#ifndef CONFIG_X86_32
	u32 gdb_regs32 = (u32 )gdb_regs;
	#endif
	regs->ax = gdb_regs[GDB_AX];
	regs->bx = gdb_regs[GDB_BX];
	regs->cx = gdb_regs[GDB_CX];
	regs->dx = gdb_regs[GDB_DX];
	regs->si = gdb_regs[GDB_SI];
	regs->di = gdb_regs[GDB_DI];
	regs->bp = gdb_regs[GDB_BP];
	regs->ip = gdb_regs[GDB_PC];
	#ifdef CONFIG_X86_32
	regs->flags = gdb_regs[GDB_PS];
	regs->ds = gdb_regs[GDB_DS];
	regs->es = gdb_regs[GDB_ES];
	regs->cs = gdb_regs[GDB_CS];
	#else
	regs->r8 = gdb_regs[GDB_R8];
	regs->r9 = gdb_regs[GDB_R9];
	regs->r10 = gdb_regs[GDB_R10];
	regs->r11 = gdb_regs[GDB_R11];
	regs->r12 = gdb_regs[GDB_R12];
	regs->r13 = gdb_regs[GDB_R13];
	regs->r14 = gdb_regs[GDB_R14];
	regs->r15 = gdb_regs[GDB_R15];
	regs->flags = gdb_regs32[GDB_PS];
	regs->cs = gdb_regs32[GDB_CS];
	regs->ss = gdb_regs32[GDB_SS];
	#endif
	}

	static struct hw_breakpoint {
	unsigned enabled;
	unsigned type;
	unsigned len;
	unsigned long addr;
	} breakinfo[4];

	static void kgdb_correct_hw_break(void)
	{
	unsigned long dr7;
	int correctit = 0;
	int breakbit;
	int breakno;

	get_debugreg(dr7, 7);
	for (breakno = 0; breakno < 4; breakno++) {
	breakbit = 2 << (breakno << 1);
	if (!(dr7 & breakbit) && breakinfo[breakno].enabled) {
	correctit = 1;
	dr7 \|= breakbit;
	dr7 &= ~(0xf0000 << (breakno << 2));
	dr7 \|= ((breakinfo[breakno].len << 2) \|
	breakinfo[breakno].type) <<
	((breakno << 2) + 16);
	if (breakno >= 0 && breakno <= 3)
	set_debugreg(breakinfo[breakno].addr, breakno);

	} else {
	if ((dr7 & breakbit) && !breakinfo[breakno].enabled) {
	correctit = 1;
	dr7 &= ~breakbit;
	dr7 &= ~(0xf0000 << (breakno << 2));
	}
	}
	}
	if (correctit)
	set_debugreg(dr7, 7);
	}

	static int
	kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
	{
	int i;

	for (i = 0; i < 4; i++)
	if (breakinfo[i].addr == addr && breakinfo[i].enabled)
	break;
	if (i == 4)
	return -1;

	breakinfo[i].enabled = 0;

	return 0;
	}

	static void kgdb_remove_all_hw_break(void)
	{
	int i;

	for (i = 0; i < 4; i++)
	memset(&breakinfo[i], 0, sizeof(struct hw_breakpoint));
	}

	static int
	kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
	{
	unsigned type;
	int i;

	for (i = 0; i < 4; i++)
	if (!breakinfo[i].enabled)
	break;
	if (i == 4)
	return -1;

	switch (bptype) {
	case BP_HARDWARE_BREAKPOINT:
	type = 0;
	len = 1;
	break;
	case BP_WRITE_WATCHPOINT:
	type = 1;
	break;
	case BP_ACCESS_WATCHPOINT:
	type = 3;
	break;
	default:
	return -1;
	}

	if (len == 1 \|\| len == 2 \|\| len == 4)
	breakinfo[i].len = len - 1;
	else
	return -1;

	breakinfo[i].enabled = 1;
	breakinfo[i].addr = addr;
	breakinfo[i].type = type;

	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.
	*/
	void kgdb_disable_hw_debug(struct pt_regs *regs)
	{
	/* Disable hardware debugging while we are in kgdb: */
	set_debugreg(0UL, 7);
	}

	/**
	* kgdb_post_primary_code - Save error vector/code numbers.
	* @regs: Original pt_regs.
	* @e_vector: Original error vector.
	* @err_code: Original error code.
	*
	* This is needed on architectures which support SMP and KGDB.
	* This function is called after all the slave cpus have been put
	* to a know spin state and the primary CPU has control over KGDB.
	*/
	void kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
	{
	/* primary processor is completely in the debugger */
	gdb_x86vector = e_vector;
	gdb_x86errcode = err_code;
	}

	#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.
	* @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.
	* @remcom_in_buffer: The buffer of the packet we have read.
	* @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
	* @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;
	unsigned long dr6;
	char *ptr;
	int newPC;

	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':
	newPC = linux_regs->ip;

	/* 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;
	kgdb_single_step = 1;
	atomic_set(&kgdb_cpu_doing_single_step,
	raw_smp_processor_id());
	}

	get_debugreg(dr6, 6);
	if (!(dr6 & 0x4000)) {
	int breakno;

	for (breakno = 0; breakno < 4; breakno++) {
	if (dr6 & (1 << breakno) &&
	breakinfo[breakno].type == 0) {
	/* Set restore flag: */
	linux_regs->flags \|= X86_EFLAGS_RF;
	break;
	}
	}
	}
	set_debugreg(0UL, 6);
	kgdb_correct_hw_break();

	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);

	return NOTIFY_STOP;
	}

	static int was_in_debug_nmi[NR_CPUS];

	static int __kgdb_notify(struct die_args *args, unsigned long cmd)
	{
	struct pt_regs *regs = args->regs;

	switch (cmd) {
	case DIE_NMI:
	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 NOTIFY_STOP;
	}
	return NOTIFY_DONE;

	case DIE_NMI_IPI:
	/* Just ignore, we will handle the roundup on DIE_NMI. */
	return NOTIFY_DONE;

	case DIE_NMIUNKNOWN:
	if (was_in_debug_nmi[raw_smp_processor_id()]) {
	was_in_debug_nmi[raw_smp_processor_id()] = 0;
	return NOTIFY_STOP;
	}
	return NOTIFY_DONE;

	case DIE_NMIWATCHDOG:
	if (atomic_read(&kgdb_active) != -1) {
	/* KGDB CPU roundup: */
	kgdb_nmicallback(raw_smp_processor_id(), regs);
	return NOTIFY_STOP;
	}
	/* Enter debugger: */
	break;

	case DIE_DEBUG:
	if (atomic_read(&kgdb_cpu_doing_single_step) ==
	raw_smp_processor_id()) {
	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, args->err, regs))
	return NOTIFY_DONE;

	/* Must touch watchdog before return to normal operation */
	touch_nmi_watchdog();
	return NOTIFY_STOP;
	}

	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,

	/*
	* Lowest-prio notifier priority, we want to be notified last:
	*/
	.priority = -INT_MAX,
	};

	/**
	* kgdb_arch_init - Perform any architecture specific initalization.
	*
	* This function will handle the initalization of any architecture
	* specific callbacks.
	*/
	int kgdb_arch_init(void)
	{
	return register_die_notifier(&kgdb_notifier);
	}

	/**
	* 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)
	{
	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);
	}

	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,
	.remove_all_hw_break = kgdb_remove_all_hw_break,
	.correct_hw_break = kgdb_correct_hw_break,
	};