Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-kgdb

* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-kgdb:
  kgdb: always use icache flush for sw breakpoints
  kgdb: fix SMP NMI kgdb_handle_exception exit race
  kgdb: documentation fixes
  kgdb: allow static kgdbts boot configuration
  kgdb: add documentation
  kgdb: Kconfig fix
  kgdb: add kgdb internal test suite
  kgdb: fix several kgdb regressions
  kgdb: kgdboc pl011 I/O module
  kgdb: fix optional arch functions and probe_kernel_*
  kgdb: add x86 HW breakpoints
  kgdb: print breakpoint removed on exception
  kgdb: clocksource watchdog
  kgdb: fix NMI hangs
  kgdb: fix kgdboc dynamic module configuration
  kgdb: document parameters
  x86: kgdb support
  consoles: polling support, kgdboc
  kgdb: core
  uaccess: add probe_kernel_write()

6 files changed, 599 insertions, 1 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 701c4a27a731..2a59dbb28248 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -23,6 +23,7 @@ config X86
         select HAVE_KPROBES
         select HAVE_KRETPROBES
         select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64)
+        select HAVE_ARCH_KGDB
 
 
 config GENERIC_LOCKBREAK
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 530ed6a4a031..c3920ea8ac56 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -67,6 +67,7 @@ obj-$(CONFIG_MODULES)		+= module_$(BITS).o
 obj-$(CONFIG_ACPI_SRAT)         += srat_32.o
 obj-$(CONFIG_EFI)               += efi.o efi_$(BITS).o efi_stub_$(BITS).o
 obj-$(CONFIG_DOUBLEFAULT)       += doublefault_32.o
+obj-$(CONFIG_KGDB)              += kgdb.o
 obj-$(CONFIG_VM86)              += vm86_32.o
 obj-$(CONFIG_EARLY_PRINTK)      += early_printk.o
 
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
new file mode 100644
index 000000000000..8c7e555f6d39
--- /dev/null
+++ b/arch/x86/kernel/kgdb.c
@@ -0,0 +1,571 @@
+/*
+ * 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>
+
+#ifdef CONFIG_X86_32
+# include <mach_ipi.h>
+#else
+# include <asm/mach_apic.h>
+#endif
+
+/*
+ * 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)
+{
+        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_PS]        = regs->flags;
+        gdb_regs[GDB_PC]        = regs->ip;
+#ifdef CONFIG_X86_32
+        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;
+#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;
+#endif
+        gdb_regs[GDB_SP]        = regs->sp;
+}
+
+/**
+ *      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)
+{
+        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_regs[GDB_PS]        = *(unsigned long *)(p->thread.sp + 8);
+        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;
+}
+
+/**
+ *      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)
+{
+        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->flags             = gdb_regs[GDB_PS];
+        regs->ip                = gdb_regs[GDB_PC];
+#ifdef CONFIG_X86_32
+        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];
+#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)
+{
+        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 &= ~TF_MASK;
+                atomic_set(&kgdb_cpu_doing_single_step, -1);
+
+                /* set the trace bit if we're stepping */
+                if (remcomInBuffer[0] == 's') {
+                        linux_regs->flags |= TF_MASK;
+                        kgdb_single_step = 1;
+                        if (kgdb_contthread) {
+                                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:
+                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_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() &&
+                        user_mode(regs))
+                        return single_step_cont(regs, args);
+                /* 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,
+};
diff --git a/arch/x86/kernel/setup64.c b/arch/x86/kernel/setup64.c
index 4be499cd6a0d..9042fb0e36f5 100644
--- a/arch/x86/kernel/setup64.c
+++ b/arch/x86/kernel/setup64.c
@@ -11,6 +11,7 @@
 #include <linux/bootmem.h>
 #include <linux/bitops.h>
 #include <linux/module.h>
+#include <linux/kgdb.h>
 #include <asm/pda.h>
 #include <asm/pgtable.h>
 #include <asm/processor.h>
@@ -251,6 +252,17 @@ void __cpuinit cpu_init (void)
         load_TR_desc();
         load_LDT(&init_mm.context);
 
+#ifdef CONFIG_KGDB
+        /*
+         * If the kgdb is connected no debug regs should be altered.  This
+         * is only applicable when KGDB and a KGDB I/O module are built
+         * into the kernel and you are using early debugging with
+         * kgdbwait. KGDB will control the kernel HW breakpoint registers.
+         */
+        if (kgdb_connected && arch_kgdb_ops.correct_hw_break)
+                arch_kgdb_ops.correct_hw_break();
+        else {
+#endif
         /*
          * Clear all 6 debug registers:
          */
@@ -261,6 +273,10 @@ void __cpuinit cpu_init (void)
         set_debugreg(0UL, 3);
         set_debugreg(0UL, 6);
         set_debugreg(0UL, 7);
+#ifdef CONFIG_KGDB
+        /* If the kgdb is connected no debug regs should be altered. */
+        }
+#endif
 
         fpu_init(); 
 
diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index bb9107c56ff5..65791ca2824a 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -730,6 +730,8 @@ io_check_error(unsigned char reason, struct pt_regs *regs)
 static __kprobes void
 unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 {
+        if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
+                return;
 #ifdef CONFIG_MCA
         /*
          * Might actually be able to figure out what the guilty party
diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c
index 33292ac814f4..79aa6fc0815c 100644
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -602,8 +602,13 @@ void die(const char * str, struct pt_regs * regs, long err)
 
 void __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic)
 {
-        unsigned long flags = oops_begin();
+        unsigned long flags;
 
+        if (notify_die(DIE_NMIWATCHDOG, str, regs, 0, 2, SIGINT) ==
+            NOTIFY_STOP)
+                return;
+
+        flags = oops_begin();
         /*
          * We are in trouble anyway, lets at least try
          * to get a message out.
@@ -808,6 +813,8 @@ io_check_error(unsigned char reason, struct pt_regs * regs)
 static __kprobes void
 unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
 {
+        if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
+                return;
         printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x.\n",
                 reason);
         printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");