mn10300: add the MN10300/AM33 architecture to the kernel

Add architecture support for the MN10300/AM33 CPUs produced by MEI to the
kernel.

This patch also adds board support for the ASB2303 with the ASB2308 daughter
board, and the ASB2305.  The only processor supported is the MN103E010, which
is an AM33v2 core plus on-chip devices.

[akpm@linux-foundation.org: nuke cvs control strings]
Signed-off-by: Masakazu Urade <urade.masakazu@jp.panasonic.com>
Signed-off-by: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 653 insertions, 0 deletions

diff --git a/arch/mn10300/kernel/kprobes.c b/arch/mn10300/kernel/kprobes.c
new file mode 100644
index 000000000000..dacafab00eb2
--- /dev/null
+++ b/arch/mn10300/kernel/kprobes.c
@@ -0,0 +1,653 @@
+/* MN10300 Kernel probes implementation
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by Mark Salter (msalter@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public Licence as published by
+ * the Free Software Foundation; either version 2 of the Licence, 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 Licence for more details.
+ *
+ * You should have received a copy of the GNU General Public Licence
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/spinlock.h>
+#include <linux/preempt.h>
+#include <linux/kdebug.h>
+#include <asm/cacheflush.h>
+
+struct kretprobe_blackpoint kretprobe_blacklist[] = { { NULL, NULL } };
+const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
+
+/* kprobe_status settings */
+#define KPROBE_HIT_ACTIVE	0x00000001
+#define KPROBE_HIT_SS		0x00000002
+
+static struct kprobe *current_kprobe;
+static unsigned long current_kprobe_orig_pc;
+static unsigned long current_kprobe_next_pc;
+static int current_kprobe_ss_flags;
+static unsigned long kprobe_status;
+static kprobe_opcode_t current_kprobe_ss_buf[MAX_INSN_SIZE + 2];
+static unsigned long current_kprobe_bp_addr;
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+
+
+/* singlestep flag bits */
+#define SINGLESTEP_BRANCH 1
+#define SINGLESTEP_PCREL  2
+
+#define READ_BYTE(p, valp) \
+	do { *(u8 *)(valp) = *(u8 *)(p); } while (0)
+
+#define READ_WORD16(p, valp)					\
+	do {							\
+		READ_BYTE((p), (valp));				\
+		READ_BYTE((u8 *)(p) + 1, (u8 *)(valp) + 1);	\
+	} while (0)
+
+#define READ_WORD32(p, valp)					\
+	do {							\
+		READ_BYTE((p), (valp));				\
+		READ_BYTE((u8 *)(p) + 1, (u8 *)(valp) + 1);	\
+		READ_BYTE((u8 *)(p) + 2, (u8 *)(valp) + 2);	\
+		READ_BYTE((u8 *)(p) + 3, (u8 *)(valp) + 3);	\
+	} while (0)
+
+
+static const u8 mn10300_insn_sizes[256] =
+{
+	/* 1  2  3  4  5  6  7  8  9  a  b  c  d  e  f */
+	1, 3, 3, 3, 1, 3, 3, 3, 1, 3, 3, 3, 1, 3, 3, 3,	/* 0 */
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 1 */
+	2, 2, 2, 2, 3, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 3, /* 2 */
+	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, /* 3 */
+	1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, /* 4 */
+	1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, /* 5 */
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 6 */
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 7 */
+	2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* 8 */
+	2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* 9 */
+	2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* a */
+	2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* b */
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 2, 2, /* c */
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* d */
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* e */
+	0, 2, 2, 2, 2, 2, 2, 4, 0, 3, 0, 4, 0, 6, 7, 1  /* f */
+};
+
+#define LT (1 << 0)
+#define GT (1 << 1)
+#define GE (1 << 2)
+#define LE (1 << 3)
+#define CS (1 << 4)
+#define HI (1 << 5)
+#define CC (1 << 6)
+#define LS (1 << 7)
+#define EQ (1 << 8)
+#define NE (1 << 9)
+#define RA (1 << 10)
+#define VC (1 << 11)
+#define VS (1 << 12)
+#define NC (1 << 13)
+#define NS (1 << 14)
+
+static const u16 cond_table[] = {
+	/*  V  C  N  Z  */
+	/*  0  0  0  0  */ (NE | NC | CC | VC | GE | GT | HI),
+	/*  0  0  0  1  */ (EQ | NC | CC | VC | GE | LE | LS),
+	/*  0  0  1  0  */ (NE | NS | CC | VC | LT | LE | HI),
+	/*  0  0  1  1  */ (EQ | NS | CC | VC | LT | LE | LS),
+	/*  0  1  0  0  */ (NE | NC | CS | VC | GE | GT | LS),
+	/*  0  1  0  1  */ (EQ | NC | CS | VC | GE | LE | LS),
+	/*  0  1  1  0  */ (NE | NS | CS | VC | LT | LE | LS),
+	/*  0  1  1  1  */ (EQ | NS | CS | VC | LT | LE | LS),
+	/*  1  0  0  0  */ (NE | NC | CC | VS | LT | LE | HI),
+	/*  1  0  0  1  */ (EQ | NC | CC | VS | LT | LE | LS),
+	/*  1  0  1  0  */ (NE | NS | CC | VS | GE | GT | HI),
+	/*  1  0  1  1  */ (EQ | NS | CC | VS | GE | LE | LS),
+	/*  1  1  0  0  */ (NE | NC | CS | VS | LT | LE | LS),
+	/*  1  1  0  1  */ (EQ | NC | CS | VS | LT | LE | LS),
+	/*  1  1  1  0  */ (NE | NS | CS | VS | GE | GT | LS),
+	/*  1  1  1  1  */ (EQ | NS | CS | VS | GE | LE | LS),
+};
+
+/*
+ * Calculate what the PC will be after executing next instruction
+ */
+static unsigned find_nextpc(struct pt_regs *regs, int *flags)
+{
+	unsigned size;
+	s8  x8;
+	s16 x16;
+	s32 x32;
+	u8 opc, *pc, *sp, *next;
+
+	next = 0;
+	*flags = SINGLESTEP_PCREL;
+
+	pc = (u8 *) regs->pc;
+	sp = (u8 *) (regs + 1);
+	opc = *pc;
+
+	size = mn10300_insn_sizes[opc];
+	if (size > 0) {
+		next = pc + size;
+	} else {
+		switch (opc) {
+			/* Bxx (d8,PC) */
+		case 0xc0 ... 0xca:
+			x8 = 2;
+			if (cond_table[regs->epsw & 0xf] & (1 << (opc & 0xf)))
+				x8 = (s8)pc[1];
+			next = pc + x8;
+			*flags |= SINGLESTEP_BRANCH;
+			break;
+
+			/* JMP (d16,PC) or CALL (d16,PC) */
+		case 0xcc:
+		case 0xcd:
+			READ_WORD16(pc + 1, &x16);
+			next = pc + x16;
+			*flags |= SINGLESTEP_BRANCH;
+			break;
+
+			/* JMP (d32,PC) or CALL (d32,PC) */
+		case 0xdc:
+		case 0xdd:
+			READ_WORD32(pc + 1, &x32);
+			next = pc + x32;
+			*flags |= SINGLESTEP_BRANCH;
+			break;
+
+			/* RETF */
+		case 0xde:
+			next = (u8 *)regs->mdr;
+			*flags &= ~SINGLESTEP_PCREL;
+			*flags |= SINGLESTEP_BRANCH;
+			break;
+
+			/* RET */
+		case 0xdf:
+			sp += pc[2];
+			READ_WORD32(sp, &x32);
+			next = (u8 *)x32;
+			*flags &= ~SINGLESTEP_PCREL;
+			*flags |= SINGLESTEP_BRANCH;
+			break;
+
+		case 0xf0:
+			next = pc + 2;
+			opc = pc[1];
+			if (opc >= 0xf0 && opc <= 0xf7) {
+				/* JMP (An) / CALLS (An) */
+				switch (opc & 3) {
+				case 0:
+					next = (u8 *)regs->a0;
+					break;
+				case 1:
+					next = (u8 *)regs->a1;
+					break;
+				case 2:
+					next = (u8 *)regs->a2;
+					break;
+				case 3:
+					next = (u8 *)regs->a3;
+					break;
+				}
+				*flags &= ~SINGLESTEP_PCREL;
+				*flags |= SINGLESTEP_BRANCH;
+			} else if (opc == 0xfc) {
+				/* RETS */
+				READ_WORD32(sp, &x32);
+				next = (u8 *)x32;
+				*flags &= ~SINGLESTEP_PCREL;
+				*flags |= SINGLESTEP_BRANCH;
+			} else if (opc == 0xfd) {
+				/* RTI */
+				READ_WORD32(sp + 4, &x32);
+				next = (u8 *)x32;
+				*flags &= ~SINGLESTEP_PCREL;
+				*flags |= SINGLESTEP_BRANCH;
+			}
+			break;
+
+			/* potential 3-byte conditional branches */
+		case 0xf8:
+			next = pc + 3;
+			opc = pc[1];
+			if (opc >= 0xe8 && opc <= 0xeb &&
+			    (cond_table[regs->epsw & 0xf] &
+			     (1 << ((opc & 0xf) + 3)))
+			    ) {
+				READ_BYTE(pc+2, &x8);
+				next = pc + x8;
+				*flags |= SINGLESTEP_BRANCH;
+			}
+			break;
+
+		case 0xfa:
+			if (pc[1] == 0xff) {
+				/* CALLS (d16,PC) */
+				READ_WORD16(pc + 2, &x16);
+				next = pc + x16;
+			} else
+				next = pc + 4;
+			*flags |= SINGLESTEP_BRANCH;
+			break;
+
+		case 0xfc:
+			x32 = 6;
+			if (pc[1] == 0xff) {
+				/* CALLS (d32,PC) */
+				READ_WORD32(pc + 2, &x32);
+			}
+			next = pc + x32;
+			*flags |= SINGLESTEP_BRANCH;
+			break;
+			/* LXX (d8,PC) */
+			/* SETLB - loads the next four bytes into the LIR reg */
+		case 0xd0 ... 0xda:
+		case 0xdb:
+			panic("Can't singlestep Lxx/SETLB\n");
+			break;
+		}
+	}
+	return (unsigned)next;
+
+}
+
+/*
+ * set up out of place singlestep of some branching instructions
+ */
+static unsigned __kprobes singlestep_branch_setup(struct pt_regs *regs)
+{
+	u8 opc, *pc, *sp, *next;
+
+	next = NULL;
+	pc = (u8 *) regs->pc;
+	sp = (u8 *) (regs + 1);
+
+	switch (pc[0]) {
+	case 0xc0 ... 0xca:	/* Bxx (d8,PC) */
+	case 0xcc:		/* JMP (d16,PC) */
+	case 0xdc:		/* JMP (d32,PC) */
+	case 0xf8:              /* Bxx (d8,PC)  3-byte version */
+		/* don't really need to do anything except cause trap  */
+		next = pc;
+		break;
+
+	case 0xcd:		/* CALL (d16,PC) */
+		pc[1] = 5;
+		pc[2] = 0;
+		next = pc + 5;
+		break;
+
+	case 0xdd:		/* CALL (d32,PC) */
+		pc[1] = 7;
+		pc[2] = 0;
+		pc[3] = 0;
+		pc[4] = 0;
+		next = pc + 7;
+		break;
+
+	case 0xde:		/* RETF */
+		next = pc + 3;
+		regs->mdr = (unsigned) next;
+		break;
+
+	case 0xdf:		/* RET */
+		sp += pc[2];
+		next = pc + 3;
+		*(unsigned *)sp = (unsigned) next;
+		break;
+
+	case 0xf0:
+		next = pc + 2;
+		opc = pc[1];
+		if (opc >= 0xf0 && opc <= 0xf3) {
+			/* CALLS (An) */
+			/* use CALLS (d16,PC) to avoid mucking with An */
+			pc[0] = 0xfa;
+			pc[1] = 0xff;
+			pc[2] = 4;
+			pc[3] = 0;
+			next = pc + 4;
+		} else if (opc >= 0xf4 && opc <= 0xf7) {
+			/* JMP (An) */
+			next = pc;
+		} else if (opc == 0xfc) {
+			/* RETS */
+			next = pc + 2;
+			*(unsigned *) sp = (unsigned) next;
+		} else if (opc == 0xfd) {
+			/* RTI */
+			next = pc + 2;
+			*(unsigned *)(sp + 4) = (unsigned) next;
+		}
+		break;
+
+	case 0xfa:	/* CALLS (d16,PC) */
+		pc[2] = 4;
+		pc[3] = 0;
+		next = pc + 4;
+		break;
+
+	case 0xfc:	/* CALLS (d32,PC) */
+		pc[2] = 6;
+		pc[3] = 0;
+		pc[4] = 0;
+		pc[5] = 0;
+		next = pc + 6;
+		break;
+
+	case 0xd0 ... 0xda:	/* LXX (d8,PC) */
+	case 0xdb:		/* SETLB */
+		panic("Can't singlestep Lxx/SETLB\n");
+	}
+
+	return (unsigned) next;
+}
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+	return 0;
+}
+
+void __kprobes arch_copy_kprobe(struct kprobe *p)
+{
+	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE);
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+	*p->addr = BREAKPOINT_INSTRUCTION;
+	flush_icache_range((unsigned long) p->addr,
+			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+	mn10300_dcache_flush();
+	mn10300_icache_inv();
+}
+
+void arch_remove_kprobe(struct kprobe *p)
+{
+}
+
+static inline
+void __kprobes disarm_kprobe(struct kprobe *p, struct pt_regs *regs)
+{
+	*p->addr = p->opcode;
+	regs->pc = (unsigned long) p->addr;
+	mn10300_dcache_flush();
+	mn10300_icache_inv();
+}
+
+static inline
+void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+	unsigned long nextpc;
+
+	current_kprobe_orig_pc = regs->pc;
+	memcpy(current_kprobe_ss_buf, &p->ainsn.insn[0], MAX_INSN_SIZE);
+	regs->pc = (unsigned long) current_kprobe_ss_buf;
+
+	nextpc = find_nextpc(regs, &current_kprobe_ss_flags);
+	if (current_kprobe_ss_flags & SINGLESTEP_PCREL)
+		current_kprobe_next_pc =
+			current_kprobe_orig_pc + (nextpc - regs->pc);
+	else
+		current_kprobe_next_pc = nextpc;
+
+	/* branching instructions need special handling */
+	if (current_kprobe_ss_flags & SINGLESTEP_BRANCH)
+		nextpc = singlestep_branch_setup(regs);
+
+	current_kprobe_bp_addr = nextpc;
+
+	*(u8 *) nextpc = BREAKPOINT_INSTRUCTION;
+	mn10300_dcache_flush_range2((unsigned) current_kprobe_ss_buf,
+				    sizeof(current_kprobe_ss_buf));
+	mn10300_icache_inv();
+}
+
+static inline int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *p;
+	int ret = 0;
+	unsigned int *addr = (unsigned int *) regs->pc;
+
+	/* We're in an interrupt, but this is clear and BUG()-safe. */
+	preempt_disable();
+
+	/* Check we're not actually recursing */
+	if (kprobe_running()) {
+		/* We *are* holding lock here, so this is safe.
+		   Disarm the probe we just hit, and ignore it. */
+		p = get_kprobe(addr);
+		if (p) {
+			disarm_kprobe(p, regs);
+			ret = 1;
+		} else {
+			p = current_kprobe;
+			if (p->break_handler && p->break_handler(p, regs))
+				goto ss_probe;
+		}
+		/* If it's not ours, can't be delete race, (we hold lock). */
+		goto no_kprobe;
+	}
+
+	p = get_kprobe(addr);
+	if (!p) {
+		if (*addr != BREAKPOINT_INSTRUCTION) {
+			/* The breakpoint instruction was removed right after
+			 * we hit it.  Another cpu has removed either a
+			 * probepoint or a debugger breakpoint at this address.
+			 * In either case, no further handling of this
+			 * interrupt is appropriate.
+			 */
+			ret = 1;
+		}
+		/* Not one of ours: let kernel handle it */
+		goto no_kprobe;
+	}
+
+	kprobe_status = KPROBE_HIT_ACTIVE;
+	current_kprobe = p;
+	if (p->pre_handler(p, regs)) {
+		/* handler has already set things up, so skip ss setup */
+		return 1;
+	}
+
+ss_probe:
+	prepare_singlestep(p, regs);
+	kprobe_status = KPROBE_HIT_SS;
+	return 1;
+
+no_kprobe:
+	preempt_enable_no_resched();
+	return ret;
+}
+
+/*
+ * Called after single-stepping.  p->addr is the address of the
+ * instruction whose first byte has been replaced by the "breakpoint"
+ * instruction.  To avoid the SMP problems that can occur when we
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction.  The address of this
+ * copy is p->ainsn.insn.
+ */
+static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
+{
+	/* we may need to fixup regs/stack after singlestepping a call insn */
+	if (current_kprobe_ss_flags & SINGLESTEP_BRANCH) {
+		regs->pc = current_kprobe_orig_pc;
+		switch (p->ainsn.insn[0]) {
+		case 0xcd:	/* CALL (d16,PC) */
+			*(unsigned *) regs->sp = regs->mdr = regs->pc + 5;
+			break;
+		case 0xdd:	/* CALL (d32,PC) */
+			/* fixup mdr and return address on stack */
+			*(unsigned *) regs->sp = regs->mdr = regs->pc + 7;
+			break;
+		case 0xf0:
+			if (p->ainsn.insn[1] >= 0xf0 &&
+			    p->ainsn.insn[1] <= 0xf3) {
+				/* CALLS (An) */
+				/* fixup MDR and return address on stack */
+				regs->mdr = regs->pc + 2;
+				*(unsigned *) regs->sp = regs->mdr;
+			}
+			break;
+
+		case 0xfa:	/* CALLS (d16,PC) */
+			/* fixup MDR and return address on stack */
+			*(unsigned *) regs->sp = regs->mdr = regs->pc + 4;
+			break;
+
+		case 0xfc:	/* CALLS (d32,PC) */
+			/* fixup MDR and return address on stack */
+			*(unsigned *) regs->sp = regs->mdr = regs->pc + 6;
+			break;
+		}
+	}
+
+	regs->pc = current_kprobe_next_pc;
+	current_kprobe_bp_addr = 0;
+}
+
+static inline int __kprobes post_kprobe_handler(struct pt_regs *regs)
+{
+	if (!kprobe_running())
+		return 0;
+
+	if (current_kprobe->post_handler)
+		current_kprobe->post_handler(current_kprobe, regs, 0);
+
+	resume_execution(current_kprobe, regs);
+	reset_current_kprobe();
+	preempt_enable_no_resched();
+	return 1;
+}
+
+/* Interrupts disabled, kprobe_lock held. */
+static inline
+int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+	if (current_kprobe->fault_handler &&
+	    current_kprobe->fault_handler(current_kprobe, regs, trapnr))
+		return 1;
+
+	if (kprobe_status & KPROBE_HIT_SS) {
+		resume_execution(current_kprobe, regs);
+		reset_current_kprobe();
+		preempt_enable_no_resched();
+	}
+	return 0;
+}
+
+/*
+ * Wrapper routine to for handling exceptions.
+ */
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+				       unsigned long val, void *data)
+{
+	struct die_args *args = data;
+
+	switch (val) {
+	case DIE_BREAKPOINT:
+		if (current_kprobe_bp_addr != args->regs->pc) {
+			if (kprobe_handler(args->regs))
+				return NOTIFY_STOP;
+		} else {
+			if (post_kprobe_handler(args->regs))
+				return NOTIFY_STOP;
+		}
+		break;
+	case DIE_GPF:
+		if (kprobe_running() &&
+		    kprobe_fault_handler(args->regs, args->trapnr))
+			return NOTIFY_STOP;
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+/* Jprobes support.  */
+static struct pt_regs jprobe_saved_regs;
+static struct pt_regs *jprobe_saved_regs_location;
+static kprobe_opcode_t jprobe_saved_stack[MAX_STACK_SIZE];
+
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct jprobe *jp = container_of(p, struct jprobe, kp);
+
+	jprobe_saved_regs_location = regs;
+	memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));
+
+	/* Save a whole stack frame, this gets arguments
+	 * pushed onto the stack after using up all the
+	 * arg registers.
+	 */
+	memcpy(&jprobe_saved_stack, regs + 1, sizeof(jprobe_saved_stack));
+
+	/* setup return addr to the jprobe handler routine */
+	regs->pc = (unsigned long) jp->entry;
+	return 1;
+}
+
+void __kprobes jprobe_return(void)
+{
+	void *orig_sp = jprobe_saved_regs_location + 1;
+
+	preempt_enable_no_resched();
+	asm volatile("		mov	%0,sp\n"
+		     ".globl	jprobe_return_bp_addr\n"
+		     "jprobe_return_bp_addr:\n\t"
+		     "		.byte	0xff\n"
+		     : : "d" (orig_sp));
+}
+
+extern void jprobe_return_bp_addr(void);
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	u8 *addr = (u8 *) regs->pc;
+
+	if (addr == (u8 *) jprobe_return_bp_addr) {
+		if (jprobe_saved_regs_location != regs) {
+			printk(KERN_ERR"JPROBE:"
+			       " Current regs (%p) does not match saved regs"
+			       " (%p).\n",
+			       regs, jprobe_saved_regs_location);
+			BUG();
+		}
+
+		/* Restore old register state.
+		 */
+		memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
+
+		memcpy(regs + 1, &jprobe_saved_stack,
+		       sizeof(jprobe_saved_stack));
+		return 1;
+	}
+	return 0;
+}
+
+int __init arch_init_kprobes(void)
+{
+	return 0;
+}