Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  debug_core,kdb: fix crash when arch does not have single step
  kgdb,x86: use macro HBP_NUM to replace magic number 4
  kgdb,mips: remove unused kgdb_cpu_doing_single_step operations
  mm,kdb,kgdb: Add a debug reference for the kdb kmap usage
  KGDB: Remove set but unused newPC
  ftrace,kdb: Allow dumping a specific cpu's buffer with ftdump
  ftrace,kdb: Extend kdb to be able to dump the ftrace buffer
  kgdb,powerpc: Replace hardcoded offset by BREAK_INSTR_SIZE
  arm,kgdb: Add ability to trap into debugger on notify_die
  gdbstub: do not directly use dbg_reg_def[] in gdb_cmd_reg_set()
  gdbstub: Implement gdbserial 'p' and 'P' packets
  kgdb,arm: Individual register get/set for arm
  kgdb,mips: Individual register get/set for mips
  kgdb,x86: Individual register get/set for x86
  kgdb,kdb: individual register set and and get API
  gdbstub: Optimize kgdb's "thread:" response for the gdb serial protocol
  kgdb: remove custom hex_to_bin()implementation

16 files changed, 801 insertions, 316 deletions

diff --git a/arch/arm/include/asm/kgdb.h b/arch/arm/include/asm/kgdb.h
index 67af4b84198..08265993227 100644
--- a/arch/arm/include/asm/kgdb.h
+++ b/arch/arm/include/asm/kgdb.h
@@ -70,11 +70,11 @@ extern int kgdb_fault_expected;
 #define _GP_REGS		16
 #define _FP_REGS		8
 #define _EXTRA_REGS		2
-#define GDB_MAX_REGS		(_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
+#define DBG_MAX_REG_NUM		(_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
 
 #define KGDB_MAX_NO_CPUS	1
 #define BUFMAX			400
-#define NUMREGBYTES		(GDB_MAX_REGS << 2)
+#define NUMREGBYTES		(DBG_MAX_REG_NUM << 2)
 #define NUMCRITREGBYTES		(32 << 2)
 
 #define _R0			0
@@ -93,7 +93,7 @@ extern int kgdb_fault_expected;
 #define _SPT			13
 #define _LR			14
 #define _PC			15
-#define _CPSR			(GDB_MAX_REGS - 1)
+#define _CPSR			(DBG_MAX_REG_NUM - 1)
 
 /*
  * So that we can denote the end of a frame for tracing,
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index c868a886411..778c2f7024f 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -10,57 +10,62 @@
  *           Deepak Saxena <dsaxena@plexity.net>
  */
 #include <linux/irq.h>
+#include <linux/kdebug.h>
 #include <linux/kgdb.h>
 #include <asm/traps.h>
 
-/* Make a local copy of the registers passed into the handler (bletch) */
-void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs)
+struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 {
-	int regno;
-
-	/* Initialize all to zero. */
-	for (regno = 0; regno < GDB_MAX_REGS; regno++)
-		gdb_regs[regno] = 0;
+	{ "r0", 4, offsetof(struct pt_regs, ARM_r0)},
+	{ "r1", 4, offsetof(struct pt_regs, ARM_r1)},
+	{ "r2", 4, offsetof(struct pt_regs, ARM_r2)},
+	{ "r3", 4, offsetof(struct pt_regs, ARM_r3)},
+	{ "r4", 4, offsetof(struct pt_regs, ARM_r4)},
+	{ "r5", 4, offsetof(struct pt_regs, ARM_r5)},
+	{ "r6", 4, offsetof(struct pt_regs, ARM_r6)},
+	{ "r7", 4, offsetof(struct pt_regs, ARM_r7)},
+	{ "r8", 4, offsetof(struct pt_regs, ARM_r8)},
+	{ "r9", 4, offsetof(struct pt_regs, ARM_r9)},
+	{ "r10", 4, offsetof(struct pt_regs, ARM_r10)},
+	{ "fp", 4, offsetof(struct pt_regs, ARM_fp)},
+	{ "ip", 4, offsetof(struct pt_regs, ARM_ip)},
+	{ "sp", 4, offsetof(struct pt_regs, ARM_sp)},
+	{ "lr", 4, offsetof(struct pt_regs, ARM_lr)},
+	{ "pc", 4, offsetof(struct pt_regs, ARM_pc)},
+	{ "f0", 12, -1 },
+	{ "f1", 12, -1 },
+	{ "f2", 12, -1 },
+	{ "f3", 12, -1 },
+	{ "f4", 12, -1 },
+	{ "f5", 12, -1 },
+	{ "f6", 12, -1 },
+	{ "f7", 12, -1 },
+	{ "fps", 4, -1 },
+	{ "cpsr", 4, offsetof(struct pt_regs, ARM_cpsr)},
+};
 
-	gdb_regs[_R0]		= kernel_regs->ARM_r0;
-	gdb_regs[_R1]		= kernel_regs->ARM_r1;
-	gdb_regs[_R2]		= kernel_regs->ARM_r2;
-	gdb_regs[_R3]		= kernel_regs->ARM_r3;
-	gdb_regs[_R4]		= kernel_regs->ARM_r4;
-	gdb_regs[_R5]		= kernel_regs->ARM_r5;
-	gdb_regs[_R6]		= kernel_regs->ARM_r6;
-	gdb_regs[_R7]		= kernel_regs->ARM_r7;
-	gdb_regs[_R8]		= kernel_regs->ARM_r8;
-	gdb_regs[_R9]		= kernel_regs->ARM_r9;
-	gdb_regs[_R10]		= kernel_regs->ARM_r10;
-	gdb_regs[_FP]		= kernel_regs->ARM_fp;
-	gdb_regs[_IP]		= kernel_regs->ARM_ip;
-	gdb_regs[_SPT]		= kernel_regs->ARM_sp;
-	gdb_regs[_LR]		= kernel_regs->ARM_lr;
-	gdb_regs[_PC]		= kernel_regs->ARM_pc;
-	gdb_regs[_CPSR]		= kernel_regs->ARM_cpsr;
+char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	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);
+	else
+		memset(mem, 0, dbg_reg_def[regno].size);
+	return dbg_reg_def[regno].name;
 }
 
-/* Copy local gdb registers back to kgdb regs, for later copy to kernel */
-void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs)
+int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
 {
-	kernel_regs->ARM_r0	= gdb_regs[_R0];
-	kernel_regs->ARM_r1	= gdb_regs[_R1];
-	kernel_regs->ARM_r2	= gdb_regs[_R2];
-	kernel_regs->ARM_r3	= gdb_regs[_R3];
-	kernel_regs->ARM_r4	= gdb_regs[_R4];
-	kernel_regs->ARM_r5	= gdb_regs[_R5];
-	kernel_regs->ARM_r6	= gdb_regs[_R6];
-	kernel_regs->ARM_r7	= gdb_regs[_R7];
-	kernel_regs->ARM_r8	= gdb_regs[_R8];
-	kernel_regs->ARM_r9	= gdb_regs[_R9];
-	kernel_regs->ARM_r10	= gdb_regs[_R10];
-	kernel_regs->ARM_fp	= gdb_regs[_FP];
-	kernel_regs->ARM_ip	= gdb_regs[_IP];
-	kernel_regs->ARM_sp	= gdb_regs[_SPT];
-	kernel_regs->ARM_lr	= gdb_regs[_LR];
-	kernel_regs->ARM_pc	= gdb_regs[_PC];
-	kernel_regs->ARM_cpsr	= gdb_regs[_CPSR];
+	if (regno >= DBG_MAX_REG_NUM || regno < 0)
+		return -EINVAL;
+
+	if (dbg_reg_def[regno].offset != -1)
+		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
+		       dbg_reg_def[regno].size);
+	return 0;
 }
 
 void
@@ -176,6 +181,33 @@ void kgdb_roundup_cpus(unsigned long flags)
        local_irq_disable();
 }
 
+static int __kgdb_notify(struct die_args *args, unsigned long cmd)
+{
+	struct pt_regs *regs = args->regs;
+
+	if (kgdb_handle_exception(1, args->signr, cmd, regs))
+		return NOTIFY_DONE;
+	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,
+	.priority	= -INT_MAX,
+};
+
+
 /**
  *	kgdb_arch_init - Perform any architecture specific initalization.
  *
@@ -184,6 +216,11 @@ void kgdb_roundup_cpus(unsigned long flags)
  */
 int kgdb_arch_init(void)
 {
+	int ret = register_die_notifier(&kgdb_notifier);
+
+	if (ret != 0)
+		return ret;
+
 	register_undef_hook(&kgdb_brkpt_hook);
 	register_undef_hook(&kgdb_compiled_brkpt_hook);
 
@@ -200,6 +237,7 @@ void kgdb_arch_exit(void)
 {
 	unregister_undef_hook(&kgdb_brkpt_hook);
 	unregister_undef_hook(&kgdb_compiled_brkpt_hook);
+	unregister_die_notifier(&kgdb_notifier);
 }
 
 /*
diff --git a/arch/mips/include/asm/kgdb.h b/arch/mips/include/asm/kgdb.h
index 19002d605ac..e6c0b0e14cc 100644
--- a/arch/mips/include/asm/kgdb.h
+++ b/arch/mips/include/asm/kgdb.h
@@ -8,28 +8,27 @@
 #if (_MIPS_ISA == _MIPS_ISA_MIPS1) || (_MIPS_ISA == _MIPS_ISA_MIPS2) || \
 	(_MIPS_ISA == _MIPS_ISA_MIPS32)
 
-#define KGDB_GDB_REG_SIZE 32
+#define KGDB_GDB_REG_SIZE	32
+#define GDB_SIZEOF_REG		sizeof(u32)
 
 #elif (_MIPS_ISA == _MIPS_ISA_MIPS3) || (_MIPS_ISA == _MIPS_ISA_MIPS4) || \
 	(_MIPS_ISA == _MIPS_ISA_MIPS64)
 
 #ifdef CONFIG_32BIT
-#define KGDB_GDB_REG_SIZE 32
+#define KGDB_GDB_REG_SIZE	32
+#define GDB_SIZEOF_REG		sizeof(u32)
 #else /* CONFIG_CPU_32BIT */
-#define KGDB_GDB_REG_SIZE 64
+#define KGDB_GDB_REG_SIZE	64
+#define GDB_SIZEOF_REG		sizeof(u64)
 #endif
 #else
 #error "Need to set KGDB_GDB_REG_SIZE for MIPS ISA"
 #endif /* _MIPS_ISA */
 
 #define BUFMAX			2048
-#if (KGDB_GDB_REG_SIZE == 32)
-#define NUMREGBYTES		(90*sizeof(u32))
-#define NUMCRITREGBYTES		(12*sizeof(u32))
-#else
-#define NUMREGBYTES		(90*sizeof(u64))
-#define NUMCRITREGBYTES		(12*sizeof(u64))
-#endif
+#define DBG_MAX_REG_NUM		72
+#define NUMREGBYTES		(DBG_MAX_REG_NUM * sizeof(GDB_SIZEOF_REG))
+#define NUMCRITREGBYTES		(12 * sizeof(GDB_SIZEOF_REG))
 #define BREAK_INSTR_SIZE	4
 #define CACHE_FLUSH_IS_SAFE	0
 
diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c
index 9b78ff6e9b8..1f4e2fa6414 100644
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -50,6 +50,151 @@ static struct hard_trap_info {
 	{ 0, 0}			/* Must be last */
 };
 
+struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
+{
+	{ "zero", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) },
+	{ "at", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) },
+	{ "v0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) },
+	{ "v1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) },
+	{ "a0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) },
+	{ "a1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) },
+	{ "a2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) },
+	{ "a3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) },
+	{ "t0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) },
+	{ "t1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) },
+	{ "t2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) },
+	{ "t3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) },
+	{ "t4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) },
+	{ "t5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) },
+	{ "t6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) },
+	{ "t7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) },
+	{ "s0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16]) },
+	{ "s1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17]) },
+	{ "s2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18]) },
+	{ "s3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19]) },
+	{ "s4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20]) },
+	{ "s5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21]) },
+	{ "s6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22]) },
+	{ "s7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23]) },
+	{ "t8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24]) },
+	{ "t9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25]) },
+	{ "k0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26]) },
+	{ "k1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27]) },
+	{ "gp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28]) },
+	{ "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29]) },
+	{ "s8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30]) },
+	{ "ra", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31]) },
+	{ "sr", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_status) },
+	{ "lo", GDB_SIZEOF_REG, offsetof(struct pt_regs, lo) },
+	{ "hi", GDB_SIZEOF_REG, offsetof(struct pt_regs, hi) },
+	{ "bad", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_badvaddr) },
+	{ "cause", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_cause) },
+	{ "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_epc) },
+	{ "f0", GDB_SIZEOF_REG, 0 },
+	{ "f1", GDB_SIZEOF_REG, 1 },
+	{ "f2", GDB_SIZEOF_REG, 2 },
+	{ "f3", GDB_SIZEOF_REG, 3 },
+	{ "f4", GDB_SIZEOF_REG, 4 },
+	{ "f5", GDB_SIZEOF_REG, 5 },
+	{ "f6", GDB_SIZEOF_REG, 6 },
+	{ "f7", GDB_SIZEOF_REG, 7 },
+	{ "f8", GDB_SIZEOF_REG, 8 },
+	{ "f9", GDB_SIZEOF_REG, 9 },
+	{ "f10", GDB_SIZEOF_REG, 10 },
+	{ "f11", GDB_SIZEOF_REG, 11 },
+	{ "f12", GDB_SIZEOF_REG, 12 },
+	{ "f13", GDB_SIZEOF_REG, 13 },
+	{ "f14", GDB_SIZEOF_REG, 14 },
+	{ "f15", GDB_SIZEOF_REG, 15 },
+	{ "f16", GDB_SIZEOF_REG, 16 },
+	{ "f17", GDB_SIZEOF_REG, 17 },
+	{ "f18", GDB_SIZEOF_REG, 18 },
+	{ "f19", GDB_SIZEOF_REG, 19 },
+	{ "f20", GDB_SIZEOF_REG, 20 },
+	{ "f21", GDB_SIZEOF_REG, 21 },
+	{ "f22", GDB_SIZEOF_REG, 22 },
+	{ "f23", GDB_SIZEOF_REG, 23 },
+	{ "f24", GDB_SIZEOF_REG, 24 },
+	{ "f25", GDB_SIZEOF_REG, 25 },
+	{ "f26", GDB_SIZEOF_REG, 26 },
+	{ "f27", GDB_SIZEOF_REG, 27 },
+	{ "f28", GDB_SIZEOF_REG, 28 },
+	{ "f29", GDB_SIZEOF_REG, 29 },
+	{ "f30", GDB_SIZEOF_REG, 30 },
+	{ "f31", GDB_SIZEOF_REG, 31 },
+	{ "fsr", GDB_SIZEOF_REG, 0 },
+	{ "fir", GDB_SIZEOF_REG, 0 },
+};
+
+int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	int fp_reg;
+
+	if (regno < 0 || regno >= DBG_MAX_REG_NUM)
+		return -EINVAL;
+
+	if (dbg_reg_def[regno].offset != -1 && regno < 38) {
+		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
+		       dbg_reg_def[regno].size);
+	} else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
+		/* FP registers 38 -> 69 */
+		if (!(regs->cp0_status & ST0_CU1))
+			return 0;
+		if (regno == 70) {
+			/* Process the fcr31/fsr (register 70) */
+			memcpy((void *)&current->thread.fpu.fcr31, mem,
+			       dbg_reg_def[regno].size);
+			goto out_save;
+		} else if (regno == 71) {
+			/* Ignore the fir (register 71) */
+			goto out_save;
+		}
+		fp_reg = dbg_reg_def[regno].offset;
+		memcpy((void *)&current->thread.fpu.fpr[fp_reg], mem,
+		       dbg_reg_def[regno].size);
+out_save:
+		restore_fp(current);
+	}
+
+	return 0;
+}
+
+char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	int fp_reg;
+
+	if (regno >= DBG_MAX_REG_NUM || regno < 0)
+		return NULL;
+
+	if (dbg_reg_def[regno].offset != -1 && regno < 38) {
+		/* First 38 registers */
+		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
+		       dbg_reg_def[regno].size);
+	} else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
+		/* FP registers 38 -> 69 */
+		if (!(regs->cp0_status & ST0_CU1))
+			goto out;
+		save_fp(current);
+		if (regno == 70) {
+			/* Process the fcr31/fsr (register 70) */
+			memcpy(mem, (void *)&current->thread.fpu.fcr31,
+			       dbg_reg_def[regno].size);
+			goto out;
+		} else if (regno == 71) {
+			/* Ignore the fir (register 71) */
+			memset(mem, 0, dbg_reg_def[regno].size);
+			goto out;
+		}
+		fp_reg = dbg_reg_def[regno].offset;
+		memcpy(mem, (void *)&current->thread.fpu.fpr[fp_reg],
+		       dbg_reg_def[regno].size);
+	}
+
+out:
+	return dbg_reg_def[regno].name;
+
+}
+
 void arch_kgdb_breakpoint(void)
 {
 	__asm__ __volatile__(
@@ -84,64 +229,6 @@ static int compute_signal(int tt)
 	return SIGHUP;		/* default for things we don't know about */
 }
 
-void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
-{
-	int reg;
-
-#if (KGDB_GDB_REG_SIZE == 32)
-	u32 *ptr = (u32 *)gdb_regs;
-#else
-	u64 *ptr = (u64 *)gdb_regs;
-#endif
-
-	for (reg = 0; reg < 32; reg++)
-		*(ptr++) = regs->regs[reg];
-
-	*(ptr++) = regs->cp0_status;
-	*(ptr++) = regs->lo;
-	*(ptr++) = regs->hi;
-	*(ptr++) = regs->cp0_badvaddr;
-	*(ptr++) = regs->cp0_cause;
-	*(ptr++) = regs->cp0_epc;
-
-	/* FP REGS */
-	if (!(current && (regs->cp0_status & ST0_CU1)))
-		return;
-
-	save_fp(current);
-	for (reg = 0; reg < 32; reg++)
-		*(ptr++) = current->thread.fpu.fpr[reg];
-}
-
-void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
-{
-	int reg;
-
-#if (KGDB_GDB_REG_SIZE == 32)
-	const u32 *ptr = (u32 *)gdb_regs;
-#else
-	const u64 *ptr = (u64 *)gdb_regs;
-#endif
-
-	for (reg = 0; reg < 32; reg++)
-		regs->regs[reg] = *(ptr++);
-
-	regs->cp0_status = *(ptr++);
-	regs->lo = *(ptr++);
-	regs->hi = *(ptr++);
-	regs->cp0_badvaddr = *(ptr++);
-	regs->cp0_cause = *(ptr++);
-	regs->cp0_epc = *(ptr++);
-
-	/* FP REGS from current */
-	if (!(current && (regs->cp0_status & ST0_CU1)))
-		return;
-
-	for (reg = 0; reg < 32; reg++)
-		current->thread.fpu.fpr[reg] = *(ptr++);
-	restore_fp(current);
-}
-
 /*
  * Similar to regs_to_gdb_regs() except that process is sleeping and so
  * we may not be able to get all the info.
@@ -242,7 +329,7 @@ static struct notifier_block kgdb_notifier = {
 };
 
 /*
- * Handle the 's' and 'c' commands
+ * Handle the 'c' command
  */
 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 			       char *remcom_in_buffer, char *remcom_out_buffer,
@@ -250,20 +337,14 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 {
 	char *ptr;
 	unsigned long address;
-	int cpu = smp_processor_id();
 
 	switch (remcom_in_buffer[0]) {
-	case 's':
 	case 'c':
 		/* handle the optional parameter */
 		ptr = &remcom_in_buffer[1];
 		if (kgdb_hex2long(&ptr, &address))
 			regs->cp0_epc = address;
 
-		atomic_set(&kgdb_cpu_doing_single_step, -1);
-		if (remcom_in_buffer[0] == 's')
-			atomic_set(&kgdb_cpu_doing_single_step, cpu);
-
 		return 0;
 	}
 
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index 82a7b228c81..7f61a3ac787 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -129,7 +129,7 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs)
 		return 0;
 
 	if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))
-		regs->nip += 4;
+		regs->nip += BREAK_INSTR_SIZE;
 
 	return 1;
 }
diff --git a/arch/x86/include/asm/kgdb.h b/arch/x86/include/asm/kgdb.h
index 006da3687cd..396f5b5fc4d 100644
--- a/arch/x86/include/asm/kgdb.h
+++ b/arch/x86/include/asm/kgdb.h
@@ -39,9 +39,11 @@ enum regnames {
 	GDB_FS,			/* 14 */
 	GDB_GS,			/* 15 */
 };
+#define GDB_ORIG_AX		41
+#define DBG_MAX_REG_NUM		16
 #define NUMREGBYTES		((GDB_GS+1)*4)
 #else /* ! CONFIG_X86_32 */
-enum regnames64 {
+enum regnames {
 	GDB_AX,			/* 0 */
 	GDB_BX,			/* 1 */
 	GDB_CX,			/* 2 */
@@ -59,15 +61,15 @@ enum regnames64 {
 	GDB_R14,		/* 14 */
 	GDB_R15,		/* 15 */
 	GDB_PC,			/* 16 */
+	GDB_PS,			/* 17 */
+	GDB_CS,			/* 18 */
+	GDB_SS,			/* 19 */
 };
-
-enum regnames32 {
-	GDB_PS = 34,
-	GDB_CS,
-	GDB_SS,
-};
-#define NUMREGBYTES		((GDB_SS+1)*4)
-#endif /* CONFIG_X86_32 */
+#define GDB_ORIG_AX		57
+#define DBG_MAX_REG_NUM		20
+/* 17 64 bit regs and 3 32 bit regs */
+#define NUMREGBYTES		((17 * 8) + (3 * 4))
+#endif /* ! CONFIG_X86_32 */
 
 static inline void arch_kgdb_breakpoint(void)
 {
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 01ab17ae2ae..ef10940e1af 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -49,55 +49,94 @@
 #include <asm/system.h>
 #include <asm/apic.h>
 
-/**
- *	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)
+struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 {
-#ifndef CONFIG_X86_32
-	u32 *gdb_regs32 = (u32 *)gdb_regs;
+#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) },
+	{ "fs", 4, -1 },
+	{ "gs", 4, -1 },
+#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, dx) },
+	{ "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) },
 #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;
+};
+
+int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (
 #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_FS]	= 0xFFFF;
-	gdb_regs[GDB_GS]	= 0xFFFF;
-	if (user_mode_vm(regs)) {
-		gdb_regs[GDB_SS] = regs->ss;
-		gdb_regs[GDB_SP] = regs->sp;
-	} else {
-		gdb_regs[GDB_SS] = __KERNEL_DS;
-		gdb_regs[GDB_SP] = kernel_stack_pointer(regs);
+	    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";
 	}
-#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]	= kernel_stack_pointer(regs);
+	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);
+
+	switch (regno) {
+#ifdef CONFIG_X86_32
+	case GDB_SS:
+		if (!user_mode_vm(regs))
+			*(unsigned long *)mem = __KERNEL_DS;
+		break;
+	case GDB_SP:
+		if (!user_mode_vm(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;
 }
 
 /**
@@ -150,54 +189,13 @@ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 	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 long		addr;
 	int			len;
 	int			type;
 	struct perf_event	**pev;
-} breakinfo[4];
+} breakinfo[HBP_NUM];
 
 static unsigned long early_dr7;
 
@@ -205,7 +203,7 @@ static void kgdb_correct_hw_break(void)
 {
 	int breakno;
 
-	for (breakno = 0; breakno < 4; breakno++) {
+	for (breakno = 0; breakno < HBP_NUM; breakno++) {
 		struct perf_event *bp;
 		struct arch_hw_breakpoint *info;
 		int val;
@@ -292,10 +290,10 @@ kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 {
 	int i;
 
-	for (i = 0; i < 4; i++)
+	for (i = 0; i < HBP_NUM; i++)
 		if (breakinfo[i].addr == addr && breakinfo[i].enabled)
 			break;
-	if (i == 4)
+	if (i == HBP_NUM)
 		return -1;
 
 	if (hw_break_release_slot(i)) {
@@ -313,7 +311,7 @@ static void kgdb_remove_all_hw_break(void)
 	int cpu = raw_smp_processor_id();
 	struct perf_event *bp;
 
-	for (i = 0; i < 4; i++) {
+	for (i = 0; i < HBP_NUM; i++) {
 		if (!breakinfo[i].enabled)
 			continue;
 		bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
@@ -333,10 +331,10 @@ kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
 {
 	int i;
 
-	for (i = 0; i < 4; i++)
+	for (i = 0; i < HBP_NUM; i++)
 		if (!breakinfo[i].enabled)
 			break;
-	if (i == 4)
+	if (i == HBP_NUM)
 		return -1;
 
 	switch (bptype) {
@@ -397,7 +395,7 @@ void kgdb_disable_hw_debug(struct pt_regs *regs)
 
 	/* Disable hardware debugging while we are in kgdb: */
 	set_debugreg(0UL, 7);
-	for (i = 0; i < 4; i++) {
+	for (i = 0; i < HBP_NUM; i++) {
 		if (!breakinfo[i].enabled)
 			continue;
 		if (dbg_is_early) {
@@ -458,7 +456,6 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
 {
 	unsigned long addr;
 	char *ptr;
-	int newPC;
 
 	switch (remcomInBuffer[0]) {
 	case 'c':
@@ -469,8 +466,6 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
 			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);
@@ -645,7 +640,7 @@ void kgdb_arch_late(void)
 	attr.bp_len = HW_BREAKPOINT_LEN_1;
 	attr.bp_type = HW_BREAKPOINT_W;
 	attr.disabled = 1;
-	for (i = 0; i < 4; i++) {
+	for (i = 0; i < HBP_NUM; i++) {
 		if (breakinfo[i].pev)
 			continue;
 		breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 9340f34d1bb..cc96f0f23e0 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -90,6 +90,19 @@ struct kgdb_bkpt {
 	enum kgdb_bpstate	state;
 };
 
+struct dbg_reg_def_t {
+	char *name;
+	int size;
+	int offset;
+};
+
+#ifndef DBG_MAX_REG_NUM
+#define DBG_MAX_REG_NUM 0
+#else
+extern struct dbg_reg_def_t dbg_reg_def[];
+extern char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs);
+extern int dbg_set_reg(int regno, void *mem, struct pt_regs *regs);
+#endif
 #ifndef KGDB_MAX_BREAKPOINTS
 # define KGDB_MAX_BREAKPOINTS	1000
 #endif
@@ -281,7 +294,7 @@ extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern struct kgdb_io *dbg_io_ops;
 
 extern int kgdb_hex2long(char **ptr, unsigned long *long_val);
-extern int kgdb_mem2hex(char *mem, char *buf, int count);
+extern char *kgdb_mem2hex(char *mem, char *buf, int count);
 extern int kgdb_hex2mem(char *buf, char *mem, int count);
 
 extern int kgdb_isremovedbreak(unsigned long addr);
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 51d14fe8764..3c2d4972d23 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -605,6 +605,8 @@ cpu_master_loop:
 		if (dbg_kdb_mode) {
 			kgdb_connected = 1;
 			error = kdb_stub(ks);
+			if (error == -1)
+				continue;
 			kgdb_connected = 0;
 		} else {
 			error = gdb_serial_stub(ks);
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index 6e81fd59566..481a7bd2dfe 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -52,17 +52,6 @@ static unsigned long		gdb_regs[(NUMREGBYTES +
  * GDB remote protocol parser:
  */
 
-static int hex(char ch)
-{
-	if ((ch >= 'a') && (ch <= 'f'))
-		return ch - 'a' + 10;
-	if ((ch >= '0') && (ch <= '9'))
-		return ch - '0';
-	if ((ch >= 'A') && (ch <= 'F'))
-		return ch - 'A' + 10;
-	return -1;
-}
-
 #ifdef CONFIG_KGDB_KDB
 static int gdbstub_read_wait(void)
 {
@@ -123,8 +112,8 @@ static void get_packet(char *buffer)
 		buffer[count] = 0;
 
 		if (ch == '#') {
-			xmitcsum = hex(gdbstub_read_wait()) << 4;
-			xmitcsum += hex(gdbstub_read_wait());
+			xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
+			xmitcsum += hex_to_bin(gdbstub_read_wait());
 
 			if (checksum != xmitcsum)
 				/* failed checksum */
@@ -236,7 +225,7 @@ void gdbstub_msg_write(const char *s, int len)
  * buf.  Return a pointer to the last char put in buf (null). May
  * return an error.
  */
-int kgdb_mem2hex(char *mem, char *buf, int count)
+char *kgdb_mem2hex(char *mem, char *buf, int count)
 {
 	char *tmp;
 	int err;
@@ -248,17 +237,16 @@ int kgdb_mem2hex(char *mem, char *buf, int count)
 	tmp = buf + count;
 
 	err = probe_kernel_read(tmp, mem, count);
-	if (!err) {
-		while (count > 0) {
-			buf = pack_hex_byte(buf, *tmp);
-			tmp++;
-			count--;
-		}
-
-		*buf = 0;
+	if (err)
+		return NULL;
+	while (count > 0) {
+		buf = pack_hex_byte(buf, *tmp);
+		tmp++;
+		count--;
 	}
+	*buf = 0;
 
-	return err;
+	return buf;
 }
 
 /*
@@ -280,8 +268,8 @@ int kgdb_hex2mem(char *buf, char *mem, int count)
 	tmp_hex = tmp_raw - 1;
 	while (tmp_hex >= buf) {
 		tmp_raw--;
-		*tmp_raw = hex(*tmp_hex--);
-		*tmp_raw |= hex(*tmp_hex--) << 4;
+		*tmp_raw = hex_to_bin(*tmp_hex--);
+		*tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
 	}
 
 	return probe_kernel_write(mem, tmp_raw, count);
@@ -304,7 +292,7 @@ int kgdb_hex2long(char **ptr, unsigned long *long_val)
 		(*ptr)++;
 	}
 	while (**ptr) {
-		hex_val = hex(**ptr);
+		hex_val = hex_to_bin(**ptr);
 		if (hex_val < 0)
 			break;
 
@@ -339,6 +327,32 @@ static int kgdb_ebin2mem(char *buf, char *mem, int count)
 	return probe_kernel_write(mem, c, size);
 }
 
+#if DBG_MAX_REG_NUM > 0
+void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+	int i;
+	int idx = 0;
+	char *ptr = (char *)gdb_regs;
+
+	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
+		dbg_get_reg(i, ptr + idx, regs);
+		idx += dbg_reg_def[i].size;
+	}
+}
+
+void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+	int i;
+	int idx = 0;
+	char *ptr = (char *)gdb_regs;
+
+	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
+		dbg_set_reg(i, ptr + idx, regs);
+		idx += dbg_reg_def[i].size;
+	}
+}
+#endif /* DBG_MAX_REG_NUM > 0 */
+
 /* Write memory due to an 'M' or 'X' packet. */
 static int write_mem_msg(int binary)
 {
@@ -378,28 +392,31 @@ static void error_packet(char *pkt, int error)
  * remapped to negative TIDs.
  */
 
-#define BUF_THREAD_ID_SIZE	16
+#define BUF_THREAD_ID_SIZE	8
 
 static char *pack_threadid(char *pkt, unsigned char *id)
 {
-	char *limit;
+	unsigned char *limit;
+	int lzero = 1;
+
+	limit = id + (BUF_THREAD_ID_SIZE / 2);
+	while (id < limit) {
+		if (!lzero || *id != 0) {
+			pkt = pack_hex_byte(pkt, *id);
+			lzero = 0;
+		}
+		id++;
+	}
 
-	limit = pkt + BUF_THREAD_ID_SIZE;
-	while (pkt < limit)
-		pkt = pack_hex_byte(pkt, *id++);
+	if (lzero)
+		pkt = pack_hex_byte(pkt, 0);
 
 	return pkt;
 }
 
 static void int_to_threadref(unsigned char *id, int value)
 {
-	unsigned char *scan;
-	int i = 4;
-
-	scan = (unsigned char *)id;
-	while (i--)
-		*scan++ = 0;
-	put_unaligned_be32(value, scan);
+	put_unaligned_be32(value, id);
 }
 
 static struct task_struct *getthread(struct pt_regs *regs, int tid)
@@ -463,8 +480,7 @@ static void gdb_cmd_status(struct kgdb_state *ks)
 	pack_hex_byte(&remcom_out_buffer[1], ks->signo);
 }
 
-/* Handle the 'g' get registers request */
-static void gdb_cmd_getregs(struct kgdb_state *ks)
+static void gdb_get_regs_helper(struct kgdb_state *ks)
 {
 	struct task_struct *thread;
 	void *local_debuggerinfo;
@@ -505,6 +521,12 @@ static void gdb_cmd_getregs(struct kgdb_state *ks)
 		 */
 		sleeping_thread_to_gdb_regs(gdb_regs, thread);
 	}
+}
+
+/* Handle the 'g' get registers request */
+static void gdb_cmd_getregs(struct kgdb_state *ks)
+{
+	gdb_get_regs_helper(ks);
 	kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 }
 
@@ -527,13 +549,13 @@ static void gdb_cmd_memread(struct kgdb_state *ks)
 	char *ptr = &remcom_in_buffer[1];
 	unsigned long length;
 	unsigned long addr;
-	int err;
+	char *err;
 
 	if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
 					kgdb_hex2long(&ptr, &length) > 0) {
 		err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
-		if (err)
-			error_packet(remcom_out_buffer, err);
+		if (!err)
+			error_packet(remcom_out_buffer, -EINVAL);
 	} else {
 		error_packet(remcom_out_buffer, -EINVAL);
 	}
@@ -550,6 +572,60 @@ static void gdb_cmd_memwrite(struct kgdb_state *ks)
 		strcpy(remcom_out_buffer, "OK");
 }
 
+#if DBG_MAX_REG_NUM > 0
+static char *gdb_hex_reg_helper(int regnum, char *out)
+{
+	int i;
+	int offset = 0;
+
+	for (i = 0; i < regnum; i++)
+		offset += dbg_reg_def[i].size;
+	return kgdb_mem2hex((char *)gdb_regs + offset, out,
+			    dbg_reg_def[i].size);
+}
+
+/* Handle the 'p' individual regster get */
+static void gdb_cmd_reg_get(struct kgdb_state *ks)
+{
+	unsigned long regnum;
+	char *ptr = &remcom_in_buffer[1];
+
+	kgdb_hex2long(&ptr, &regnum);
+	if (regnum >= DBG_MAX_REG_NUM) {
+		error_packet(remcom_out_buffer, -EINVAL);
+		return;
+	}
+	gdb_get_regs_helper(ks);
+	gdb_hex_reg_helper(regnum, remcom_out_buffer);
+}
+
+/* Handle the 'P' individual regster set */
+static void gdb_cmd_reg_set(struct kgdb_state *ks)
+{
+	unsigned long regnum;
+	char *ptr = &remcom_in_buffer[1];
+	int i = 0;
+
+	kgdb_hex2long(&ptr, &regnum);
+	if (*ptr++ != '=' ||
+	    !(!kgdb_usethread || kgdb_usethread == current) ||
+	    !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
+		error_packet(remcom_out_buffer, -EINVAL);
+		return;
+	}
+	memset(gdb_regs, 0, sizeof(gdb_regs));
+	while (i < sizeof(gdb_regs) * 2)
+		if (hex_to_bin(ptr[i]) >= 0)
+			i++;
+		else
+			break;
+	i = i / 2;
+	kgdb_hex2mem(ptr, (char *)gdb_regs, i);
+	dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
+	strcpy(remcom_out_buffer, "OK");
+}
+#endif /* DBG_MAX_REG_NUM > 0 */
+
 /* Handle the 'X' memory binary write bytes */
 static void gdb_cmd_binwrite(struct kgdb_state *ks)
 {
@@ -612,7 +688,7 @@ static void gdb_cmd_query(struct kgdb_state *ks)
 {
 	struct task_struct *g;
 	struct task_struct *p;
-	unsigned char thref[8];
+	unsigned char thref[BUF_THREAD_ID_SIZE];
 	char *ptr;
 	int i;
 	int cpu;
@@ -632,8 +708,7 @@ static void gdb_cmd_query(struct kgdb_state *ks)
 			for_each_online_cpu(cpu) {
 				ks->thr_query = 0;
 				int_to_threadref(thref, -cpu - 2);
-				pack_threadid(ptr, thref);
-				ptr += BUF_THREAD_ID_SIZE;
+				ptr = pack_threadid(ptr, thref);
 				*(ptr++) = ',';
 				i++;
 			}
@@ -642,8 +717,7 @@ static void gdb_cmd_query(struct kgdb_state *ks)
 		do_each_thread(g, p) {
 			if (i >= ks->thr_query && !finished) {
 				int_to_threadref(thref, p->pid);
-				pack_threadid(ptr, thref);
-				ptr += BUF_THREAD_ID_SIZE;
+				ptr = pack_threadid(ptr, thref);
 				*(ptr++) = ',';
 				ks->thr_query++;
 				if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
@@ -858,11 +932,14 @@ int gdb_serial_stub(struct kgdb_state *ks)
 	int error = 0;
 	int tmp;
 
-	/* Clear the out buffer. */
+	/* Initialize comm buffer and globals. */
 	memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
+	kgdb_usethread = kgdb_info[ks->cpu].task;
+	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
+	ks->pass_exception = 0;
 
 	if (kgdb_connected) {
-		unsigned char thref[8];
+		unsigned char thref[BUF_THREAD_ID_SIZE];
 		char *ptr;
 
 		/* Reply to host that an exception has occurred */
@@ -876,10 +953,6 @@ int gdb_serial_stub(struct kgdb_state *ks)
 		put_packet(remcom_out_buffer);
 	}
 
-	kgdb_usethread = kgdb_info[ks->cpu].task;
-	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
-	ks->pass_exception = 0;
-
 	while (1) {
 		error = 0;
 
@@ -904,6 +977,14 @@ int gdb_serial_stub(struct kgdb_state *ks)
 		case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 			gdb_cmd_memwrite(ks);
 			break;
+#if DBG_MAX_REG_NUM > 0
+		case 'p': /* pXX Return gdb register XX (in hex) */
+			gdb_cmd_reg_get(ks);
+			break;
+		case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
+			gdb_cmd_reg_set(ks);
+			break;
+#endif /* DBG_MAX_REG_NUM > 0 */
 		case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 			gdb_cmd_binwrite(ks);
 			break;
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index ebe4a287419..8577e45a9a5 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -312,7 +312,7 @@ int kdbgetularg(const char *arg, unsigned long *value)
 
 	if (endp == arg) {
 		/*
-		 * Try base 16, for us folks too lazy to type the
+		 * Also try base 16, for us folks too lazy to type the
 		 * leading 0x...
 		 */
 		val = simple_strtoul(arg, &endp, 16);
@@ -325,6 +325,25 @@ int kdbgetularg(const char *arg, unsigned long *value)
 	return 0;
 }
 
+int kdbgetu64arg(const char *arg, u64 *value)
+{
+	char *endp;
+	u64 val;
+
+	val = simple_strtoull(arg, &endp, 0);
+
+	if (endp == arg) {
+
+		val = simple_strtoull(arg, &endp, 16);
+		if (endp == arg)
+			return KDB_BADINT;
+	}
+
+	*value = val;
+
+	return 0;
+}
+
 /*
  * kdb_set - This function implements the 'set' command.  Alter an
  *	existing environment variable or create a new one.
@@ -1770,11 +1789,65 @@ static int kdb_go(int argc, const char **argv)
  */
 static int kdb_rd(int argc, const char **argv)
 {
-	int diag = kdb_check_regs();
-	if (diag)
-		return diag;
+	int len = kdb_check_regs();
+#if DBG_MAX_REG_NUM > 0
+	int i;
+	char *rname;
+	int rsize;
+	u64 reg64;
+	u32 reg32;
+	u16 reg16;
+	u8 reg8;
+
+	if (len)
+		return len;
+
+	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
+		rsize = dbg_reg_def[i].size * 2;
+		if (rsize > 16)
+			rsize = 2;
+		if (len + strlen(dbg_reg_def[i].name) + 4 + rsize > 80) {
+			len = 0;
+			kdb_printf("\n");
+		}
+		if (len)
+			len += kdb_printf("  ");
+		switch(dbg_reg_def[i].size * 8) {
+		case 8:
+			rname = dbg_get_reg(i, &reg8, kdb_current_regs);
+			if (!rname)
+				break;
+			len += kdb_printf("%s: %02x", rname, reg8);
+			break;
+		case 16:
+			rname = dbg_get_reg(i, &reg16, kdb_current_regs);
+			if (!rname)
+				break;
+			len += kdb_printf("%s: %04x", rname, reg16);
+			break;
+		case 32:
+			rname = dbg_get_reg(i, &reg32, kdb_current_regs);
+			if (!rname)
+				break;
+			len += kdb_printf("%s: %08x", rname, reg32);
+			break;
+		case 64:
+			rname = dbg_get_reg(i, &reg64, kdb_current_regs);
+			if (!rname)
+				break;
+			len += kdb_printf("%s: %016llx", rname, reg64);
+			break;
+		default:
+			len += kdb_printf("%s: ??", dbg_reg_def[i].name);
+		}
+	}
+	kdb_printf("\n");
+#else
+	if (len)
+		return len;
 
 	kdb_dumpregs(kdb_current_regs);
+#endif
 	return 0;
 }
 
@@ -1782,32 +1855,67 @@ static int kdb_rd(int argc, const char **argv)
  * kdb_rm - This function implements the 'rm' (register modify)  command.
  *	rm register-name new-contents
  * Remarks:
- *	Currently doesn't allow modification of control or
- *	debug registers.
+ *	Allows register modification with the same restrictions as gdb
  */
 static int kdb_rm(int argc, const char **argv)
 {
+#if DBG_MAX_REG_NUM > 0
 	int diag;
-	int ind = 0;
-	unsigned long contents;
+	const char *rname;
+	int i;
+	u64 reg64;
+	u32 reg32;
+	u16 reg16;
+	u8 reg8;
 
 	if (argc != 2)
 		return KDB_ARGCOUNT;
 	/*
 	 * Allow presence or absence of leading '%' symbol.
 	 */
-	if (argv[1][0] == '%')
-		ind = 1;
+	rname = argv[1];
+	if (*rname == '%')
+		rname++;
 
-	diag = kdbgetularg(argv[2], &contents);
+	diag = kdbgetu64arg(argv[2], &reg64);
 	if (diag)
 		return diag;
 
 	diag = kdb_check_regs();
 	if (diag)
 		return diag;
+
+	diag = KDB_BADREG;
+	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
+		if (strcmp(rname, dbg_reg_def[i].name) == 0) {
+			diag = 0;
+			break;
+		}
+	}
+	if (!diag) {
+		switch(dbg_reg_def[i].size * 8) {
+		case 8:
+			reg8 = reg64;
+			dbg_set_reg(i, &reg8, kdb_current_regs);
+			break;
+		case 16:
+			reg16 = reg64;
+			dbg_set_reg(i, &reg16, kdb_current_regs);
+			break;
+		case 32:
+			reg32 = reg64;
+			dbg_set_reg(i, &reg32, kdb_current_regs);
+			break;
+		case 64:
+			dbg_set_reg(i, &reg64, kdb_current_regs);
+			break;
+		}
+	}
+	return diag;
+#else
 	kdb_printf("ERROR: Register set currently not implemented\n");
-	return 0;
+    return 0;
+#endif
 }
 
 #if defined(CONFIG_MAGIC_SYSRQ)
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index ffb1a5b0550..4215530b490 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -57,5 +57,8 @@ obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
 obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
 obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
 obj-$(CONFIG_EVENT_TRACING) += power-traces.o
+ifeq ($(CONFIG_TRACING),y)
+obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
+endif
 
 libftrace-y := ftrace.o
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 086d3631680..d6736b93dc2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -101,10 +101,7 @@ static inline void ftrace_enable_cpu(void)
 	preempt_enable();
 }
 
-static cpumask_var_t __read_mostly	tracing_buffer_mask;
-
-#define for_each_tracing_cpu(cpu)	\
-	for_each_cpu(cpu, tracing_buffer_mask)
+cpumask_var_t __read_mostly	tracing_buffer_mask;
 
 /*
  * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
@@ -1539,11 +1536,6 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
 }
 EXPORT_SYMBOL_GPL(trace_vprintk);
 
-enum trace_file_type {
-	TRACE_FILE_LAT_FMT	= 1,
-	TRACE_FILE_ANNOTATE	= 2,
-};
-
 static void trace_iterator_increment(struct trace_iterator *iter)
 {
 	/* Don't allow ftrace to trace into the ring buffers */
@@ -1641,7 +1633,7 @@ struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
 }
 
 /* Find the next real entry, and increment the iterator to the next entry */
-static void *find_next_entry_inc(struct trace_iterator *iter)
+void *trace_find_next_entry_inc(struct trace_iterator *iter)
 {
 	iter->ent = __find_next_entry(iter, &iter->cpu,
 				      &iter->lost_events, &iter->ts);
@@ -1676,19 +1668,19 @@ static void *s_next(struct seq_file *m, void *v, loff_t *pos)
 		return NULL;
 
 	if (iter->idx < 0)
-		ent = find_next_entry_inc(iter);
+		ent = trace_find_next_entry_inc(iter);
 	else
 		ent = iter;
 
 	while (ent && iter->idx < i)
-		ent = find_next_entry_inc(iter);
+		ent = trace_find_next_entry_inc(iter);
 
 	iter->pos = *pos;
 
 	return ent;
 }
 
-static void tracing_iter_reset(struct trace_iterator *iter, int cpu)
+void tracing_iter_reset(struct trace_iterator *iter, int cpu)
 {
 	struct trace_array *tr = iter->tr;
 	struct ring_buffer_event *event;
@@ -2049,7 +2041,7 @@ int trace_empty(struct trace_iterator *iter)
 }
 
 /*  Called with trace_event_read_lock() held. */
-static enum print_line_t print_trace_line(struct trace_iterator *iter)
+enum print_line_t print_trace_line(struct trace_iterator *iter)
 {
 	enum print_line_t ret;
 
@@ -3211,7 +3203,7 @@ waitagain:
 
 	trace_event_read_lock();
 	trace_access_lock(iter->cpu_file);
-	while (find_next_entry_inc(iter) != NULL) {
+	while (trace_find_next_entry_inc(iter) != NULL) {
 		enum print_line_t ret;
 		int len = iter->seq.len;
 
@@ -3294,7 +3286,7 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 		if (ret != TRACE_TYPE_NO_CONSUME)
 			trace_consume(iter);
 		rem -= count;
-		if (!find_next_entry_inc(iter))	{
+		if (!trace_find_next_entry_inc(iter))	{
 			rem = 0;
 			iter->ent = NULL;
 			break;
@@ -3350,7 +3342,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 	if (ret <= 0)
 		goto out_err;
 
-	if (!iter->ent && !find_next_entry_inc(iter)) {
+	if (!iter->ent && !trace_find_next_entry_inc(iter)) {
 		ret = -EFAULT;
 		goto out_err;
 	}
@@ -4414,7 +4406,7 @@ static struct notifier_block trace_die_notifier = {
  */
 #define KERN_TRACE		KERN_EMERG
 
-static void
+void
 trace_printk_seq(struct trace_seq *s)
 {
 	/* Probably should print a warning here. */
@@ -4429,6 +4421,13 @@ trace_printk_seq(struct trace_seq *s)
 	trace_seq_init(s);
 }
 
+void trace_init_global_iter(struct trace_iterator *iter)
+{
+	iter->tr = &global_trace;
+	iter->trace = current_trace;
+	iter->cpu_file = TRACE_PIPE_ALL_CPU;
+}
+
 static void
 __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
 {
@@ -4454,8 +4453,10 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
 	if (disable_tracing)
 		ftrace_kill();
 
+	trace_init_global_iter(&iter);
+
 	for_each_tracing_cpu(cpu) {
-		atomic_inc(&global_trace.data[cpu]->disabled);
+		atomic_inc(&iter.tr->data[cpu]->disabled);
 	}
 
 	old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
@@ -4504,7 +4505,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
 		iter.iter_flags |= TRACE_FILE_LAT_FMT;
 		iter.pos = -1;
 
-		if (find_next_entry_inc(&iter) != NULL) {
+		if (trace_find_next_entry_inc(&iter) != NULL) {
 			int ret;
 
 			ret = print_trace_line(&iter);
@@ -4526,7 +4527,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
 		trace_flags |= old_userobj;
 
 		for_each_tracing_cpu(cpu) {
-			atomic_dec(&global_trace.data[cpu]->disabled);
+			atomic_dec(&iter.tr->data[cpu]->disabled);
 		}
 		tracing_on();
 	}
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2cd96399463..0605fc00c17 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -338,6 +338,14 @@ struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
 					  int *ent_cpu, u64 *ent_ts);
 
+int trace_empty(struct trace_iterator *iter);
+
+void *trace_find_next_entry_inc(struct trace_iterator *iter);
+
+void trace_init_global_iter(struct trace_iterator *iter);
+
+void tracing_iter_reset(struct trace_iterator *iter, int cpu);
+
 void default_wait_pipe(struct trace_iterator *iter);
 void poll_wait_pipe(struct trace_iterator *iter);
 
@@ -380,6 +388,15 @@ void tracing_start_sched_switch_record(void);
 int register_tracer(struct tracer *type);
 void unregister_tracer(struct tracer *type);
 int is_tracing_stopped(void);
+enum trace_file_type {
+	TRACE_FILE_LAT_FMT	= 1,
+	TRACE_FILE_ANNOTATE	= 2,
+};
+
+extern cpumask_var_t __read_mostly tracing_buffer_mask;
+
+#define for_each_tracing_cpu(cpu)	\
+	for_each_cpu(cpu, tracing_buffer_mask)
 
 extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);
 
@@ -471,6 +488,8 @@ trace_array_vprintk(struct trace_array *tr,
 		    unsigned long ip, const char *fmt, va_list args);
 int trace_array_printk(struct trace_array *tr,
 		       unsigned long ip, const char *fmt, ...);
+void trace_printk_seq(struct trace_seq *s);
+enum print_line_t print_trace_line(struct trace_iterator *iter);
 
 extern unsigned long trace_flags;
 
diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
new file mode 100644
index 00000000000..7b8ecd751d9
--- /dev/null
+++ b/kernel/trace/trace_kdb.c
@@ -0,0 +1,136 @@
+/*
+ * kdb helper for dumping the ftrace buffer
+ *
+ * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
+ *
+ * ftrace_dump_buf based on ftrace_dump:
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ */
+#include <linux/init.h>
+#include <linux/kgdb.h>
+#include <linux/kdb.h>
+#include <linux/ftrace.h>
+
+#include "../debug/kdb/kdb_private.h"
+#include "trace.h"
+#include "trace_output.h"
+
+static void ftrace_dump_buf(int skip_lines, long cpu_file)
+{
+	/* use static because iter can be a bit big for the stack */
+	static struct trace_iterator iter;
+	unsigned int old_userobj;
+	int cnt = 0, cpu;
+
+	trace_init_global_iter(&iter);
+
+	for_each_tracing_cpu(cpu) {
+		atomic_inc(&iter.tr->data[cpu]->disabled);
+	}
+
+	old_userobj = trace_flags;
+
+	/* don't look at user memory in panic mode */
+	trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
+
+	kdb_printf("Dumping ftrace buffer:\n");
+
+	/* reset all but tr, trace, and overruns */
+	memset(&iter.seq, 0,
+		   sizeof(struct trace_iterator) -
+		   offsetof(struct trace_iterator, seq));
+	iter.iter_flags |= TRACE_FILE_LAT_FMT;
+	iter.pos = -1;
+
+	if (cpu_file == TRACE_PIPE_ALL_CPU) {
+		for_each_tracing_cpu(cpu) {
+			iter.buffer_iter[cpu] =
+			ring_buffer_read_prepare(iter.tr->buffer, cpu);
+			ring_buffer_read_start(iter.buffer_iter[cpu]);
+			tracing_iter_reset(&iter, cpu);
+		}
+	} else {
+		iter.cpu_file = cpu_file;
+		iter.buffer_iter[cpu_file] =
+			ring_buffer_read_prepare(iter.tr->buffer, cpu_file);
+		ring_buffer_read_start(iter.buffer_iter[cpu_file]);
+		tracing_iter_reset(&iter, cpu_file);
+	}
+	if (!trace_empty(&iter))
+		trace_find_next_entry_inc(&iter);
+	while (!trace_empty(&iter)) {
+		if (!cnt)
+			kdb_printf("---------------------------------\n");
+		cnt++;
+
+		if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines)
+			print_trace_line(&iter);
+		if (!skip_lines)
+			trace_printk_seq(&iter.seq);
+		else
+			skip_lines--;
+		if (KDB_FLAG(CMD_INTERRUPT))
+			goto out;
+	}
+
+	if (!cnt)
+		kdb_printf("   (ftrace buffer empty)\n");
+	else
+		kdb_printf("---------------------------------\n");
+
+out:
+	trace_flags = old_userobj;
+
+	for_each_tracing_cpu(cpu) {
+		atomic_dec(&iter.tr->data[cpu]->disabled);
+	}
+
+	for_each_tracing_cpu(cpu)
+		if (iter.buffer_iter[cpu])
+			ring_buffer_read_finish(iter.buffer_iter[cpu]);
+}
+
+/*
+ * kdb_ftdump - Dump the ftrace log buffer
+ */
+static int kdb_ftdump(int argc, const char **argv)
+{
+	int skip_lines = 0;
+	long cpu_file;
+	char *cp;
+
+	if (argc > 2)
+		return KDB_ARGCOUNT;
+
+	if (argc) {
+		skip_lines = simple_strtol(argv[1], &cp, 0);
+		if (*cp)
+			skip_lines = 0;
+	}
+
+	if (argc == 2) {
+		cpu_file = simple_strtol(argv[2], &cp, 0);
+		if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
+		    !cpu_online(cpu_file))
+			return KDB_BADINT;
+	} else {
+		cpu_file = TRACE_PIPE_ALL_CPU;
+	}
+
+	kdb_trap_printk++;
+	ftrace_dump_buf(skip_lines, cpu_file);
+	kdb_trap_printk--;
+
+	return 0;
+}
+
+static __init int kdb_ftrace_register(void)
+{
+	kdb_register_repeat("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
+			    "Dump ftrace log", 0, KDB_REPEAT_NONE);
+	return 0;
+}
+
+late_initcall(kdb_ftrace_register);
diff --git a/mm/highmem.c b/mm/highmem.c
index 66baa20f78f..7a0aa1be499 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -26,6 +26,7 @@
 #include <linux/init.h>
 #include <linux/hash.h>
 #include <linux/highmem.h>
+#include <linux/kgdb.h>
 #include <asm/tlbflush.h>
 
 /*
@@ -470,6 +471,12 @@ void debug_kmap_atomic(enum km_type type)
 			warn_count--;
 		}
 	}
+#ifdef CONFIG_KGDB_KDB
+	if (unlikely(type == KM_KDB && atomic_read(&kgdb_active) == -1)) {
+		WARN_ON(1);
+		warn_count--;
+	}
+#endif /* CONFIG_KGDB_KDB */
 }
 
 #endif