arch/arc/kernel/disasm.c - pub/scm/linux/kernel/git/ebiederm/net-next - Git at Google

 /*
  * several functions that help interpret ARC instructions
  * used for unaligned accesses, kprobes and kgdb
  *
  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/types.h>
 #include <linux/kprobes.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <asm/disasm.h>

 #if defined(CONFIG_KGDB) || defined(CONFIG_ARC_MISALIGN_ACCESS) || \
 	defined(CONFIG_KPROBES)

 /* disasm_instr: Analyses instruction at addr, stores
  * findings in *state
  */
 void __kprobes disasm_instr(unsigned long addr, struct disasm_state *state,
 	int userspace, struct pt_regs *regs, struct callee_regs *cregs)
 {
 	int fieldA = 0;
 	int fieldC = 0, fieldCisReg = 0;
 	uint16_t word1 = 0, word0 = 0;
 	int subopcode, is_linked, op_format;
 	uint16_t *ins_ptr;
 	uint16_t ins_buf[4];
 	int bytes_not_copied = 0;

 	memset(state, 0, sizeof(struct disasm_state));

 	/* This fetches the upper part of the 32 bit instruction
 	 * in both the cases of Little Endian or Big Endian configurations. */
 	if (userspace) {
 		bytes_not_copied = copy_from_user(ins_buf,
 						(const void __user *) addr, 8);
 		if (bytes_not_copied > 6)
 			goto fault;
 		ins_ptr = ins_buf;
 	} else {
 		ins_ptr = (uint16_t *) addr;
 	}

 	word1 = *((uint16_t *)addr);

 	state->major_opcode = (word1 >> 11) & 0x1F;

 	/* Check if the instruction is 32 bit or 16 bit instruction */
 	if (state->major_opcode < 0x0B) {
 		if (bytes_not_copied > 4)
 			goto fault;
 		state->instr_len = 4;
 		word0 = *((uint16_t *)(addr+2));
 		state->words[0] = (word1 << 16) | word0;
 	} else {
 		state->instr_len = 2;
 		state->words[0] = word1;
 	}

 	/* Read the second word in case of limm */
 	word1 = *((uint16_t *)(addr + state->instr_len));
 	word0 = *((uint16_t *)(addr + state->instr_len + 2));
 	state->words[1] = (word1 << 16) | word0;

 	switch (state->major_opcode) {
 	case op_Bcc:
 		state->is_branch = 1;

 		/* unconditional branch s25, conditional branch s21 */
 		fieldA = (IS_BIT(state->words[0], 16)) ?
 			FIELD_s25(state->words[0]) :
 			FIELD_s21(state->words[0]);

 		state->delay_slot = IS_BIT(state->words[0], 5);
 		state->target = fieldA + (addr & ~0x3);
 		state->flow = direct_jump;
 		break;

 	case op_BLcc:
 		if (IS_BIT(state->words[0], 16)) {
 			/* Branch and Link*/
 			/* unconditional branch s25, conditional branch s21 */
 			fieldA = (IS_BIT(state->words[0], 17)) ?
 				(FIELD_s25(state->words[0]) & ~0x3) :
 				FIELD_s21(state->words[0]);

 			state->flow = direct_call;
 		} else {
 			/*Branch On Compare */
 			fieldA = FIELD_s9(state->words[0]) & ~0x3;
 			state->flow = direct_jump;
 		}

 		state->delay_slot = IS_BIT(state->words[0], 5);
 		state->target = fieldA + (addr & ~0x3);
 		state->is_branch = 1;
 		break;

 	case op_LD:  /* LD<zz> a,[b,s9] */
 		state->write = 0;
 		state->di = BITS(state->words[0], 11, 11);
 		if (state->di)
 			break;
 		state->x = BITS(state->words[0], 6, 6);
 		state->zz = BITS(state->words[0], 7, 8);
 		state->aa = BITS(state->words[0], 9, 10);
 		state->wb_reg = FIELD_B(state->words[0]);
 		if (state->wb_reg == REG_LIMM) {
 			state->instr_len += 4;
 			state->aa = 0;
 			state->src1 = state->words[1];
 		} else {
 			state->src1 = get_reg(state->wb_reg, regs, cregs);
 		}
 		state->src2 = FIELD_s9(state->words[0]);
 		state->dest = FIELD_A(state->words[0]);
 		state->pref = (state->dest == REG_LIMM);
 		break;

 	case op_ST:
 		state->write = 1;
 		state->di = BITS(state->words[0], 5, 5);
 		if (state->di)
 			break;
 		state->aa = BITS(state->words[0], 3, 4);
 		state->zz = BITS(state->words[0], 1, 2);
 		state->src1 = FIELD_C(state->words[0]);
 		if (state->src1 == REG_LIMM) {
 			state->instr_len += 4;
 			state->src1 = state->words[1];
 		} else {
 			state->src1 = get_reg(state->src1, regs, cregs);
 		}
 		state->wb_reg = FIELD_B(state->words[0]);
 		if (state->wb_reg == REG_LIMM) {
 			state->aa = 0;
 			state->instr_len += 4;
 			state->src2 = state->words[1];
 		} else {
 			state->src2 = get_reg(state->wb_reg, regs, cregs);
 		}
 		state->src3 = FIELD_s9(state->words[0]);
 		break;

 	case op_MAJOR_4:
 		subopcode = MINOR_OPCODE(state->words[0]);
 		switch (subopcode) {
 		case 32:	/* Jcc */
 		case 33:	/* Jcc.D */
 		case 34:	/* JLcc */
 		case 35:	/* JLcc.D */
 			is_linked = 0;

 			if (subopcode == 33 || subopcode == 35)
 				state->delay_slot = 1;

 			if (subopcode == 34 || subopcode == 35)
 				is_linked = 1;

 			fieldCisReg = 0;
 			op_format = BITS(state->words[0], 22, 23);
 			if (op_format == 0 || ((op_format == 3) &&
 				(!IS_BIT(state->words[0], 5)))) {
 				fieldC = FIELD_C(state->words[0]);

 				if (fieldC == REG_LIMM) {
 					fieldC = state->words[1];
 					state->instr_len += 4;
 				} else {
 					fieldCisReg = 1;
 				}
 			} else if (op_format == 1 || ((op_format == 3)
 				&& (IS_BIT(state->words[0], 5)))) {
 				fieldC = FIELD_C(state->words[0]);
 			} else  {
 				/* op_format == 2 */
 				fieldC = FIELD_s12(state->words[0]);
 			}

 			if (!fieldCisReg) {
 				state->target = fieldC;
 				state->flow = is_linked ?
 					direct_call : direct_jump;
 			} else {
 				state->target = get_reg(fieldC, regs, cregs);
 				state->flow = is_linked ?
 					indirect_call : indirect_jump;
 			}
 			state->is_branch = 1;
 			break;

 		case 40:	/* LPcc */
 			if (BITS(state->words[0], 22, 23) == 3) {
 				/* Conditional LPcc u7 */
 				fieldC = FIELD_C(state->words[0]);

 				fieldC = fieldC << 1;
 				fieldC += (addr & ~0x03);
 				state->is_branch = 1;
 				state->flow = direct_jump;
 				state->target = fieldC;
 			}
 			/* For Unconditional lp, next pc is the fall through
 			 * which is updated */
 			break;

 		case 48 ... 55:	/* LD a,[b,c] */
 			state->di = BITS(state->words[0], 15, 15);
 			if (state->di)
 				break;
 			state->x = BITS(state->words[0], 16, 16);
 			state->zz = BITS(state->words[0], 17, 18);
 			state->aa = BITS(state->words[0], 22, 23);
 			state->wb_reg = FIELD_B(state->words[0]);
 			if (state->wb_reg == REG_LIMM) {
 				state->instr_len += 4;
 				state->src1 = state->words[1];
 			} else {
 				state->src1 = get_reg(state->wb_reg, regs,
 						cregs);
 			}
 			state->src2 = FIELD_C(state->words[0]);
 			if (state->src2 == REG_LIMM) {
 				state->instr_len += 4;
 				state->src2 = state->words[1];
 			} else {
 				state->src2 = get_reg(state->src2, regs,
 					cregs);
 			}
 			state->dest = FIELD_A(state->words[0]);
 			if (state->dest == REG_LIMM)
 				state->pref = 1;
 			break;

 		case 10:	/* MOV */
 			/* still need to check for limm to extract instr len */
 			/* MOV is special case because it only takes 2 args */
 			switch (BITS(state->words[0], 22, 23)) {
 			case 0: /* OP a,b,c */
 				if (FIELD_C(state->words[0]) == REG_LIMM)
 					state->instr_len += 4;
 				break;
 			case 1: /* OP a,b,u6 */
 				break;
 			case 2: /* OP b,b,s12 */
 				break;
 			case 3: /* OP.cc b,b,c/u6 */
 				if ((!IS_BIT(state->words[0], 5)) &&
 				    (FIELD_C(state->words[0]) == REG_LIMM))
 					state->instr_len += 4;
 				break;
 			}
 			break;


 		default:
 			/* Not a Load, Jump or Loop instruction */
 			/* still need to check for limm to extract instr len */
 			switch (BITS(state->words[0], 22, 23)) {
 			case 0: /* OP a,b,c */
 				if ((FIELD_B(state->words[0]) == REG_LIMM) ||
 				    (FIELD_C(state->words[0]) == REG_LIMM))
 					state->instr_len += 4;
 				break;
 			case 1: /* OP a,b,u6 */
 				break;
 			case 2: /* OP b,b,s12 */
 				break;
 			case 3: /* OP.cc b,b,c/u6 */
 				if ((!IS_BIT(state->words[0], 5)) &&
 				   ((FIELD_B(state->words[0]) == REG_LIMM) ||
 				    (FIELD_C(state->words[0]) == REG_LIMM)))
 					state->instr_len += 4;
 				break;
 			}
 			break;
 		}
 		break;

 	/* 16 Bit Instructions */
 	case op_LD_ADD: /* LD_S|LDB_S|LDW_S a,[b,c] */
 		state->zz = BITS(state->words[0], 3, 4);
 		state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
 		state->src2 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
 		state->dest = FIELD_S_A(state->words[0]);
 		break;

 	case op_ADD_MOV_CMP:
 		/* check for limm, ignore mov_s h,b (== mov_s 0,b) */
 		if ((BITS(state->words[0], 3, 4) < 3) &&
 		    (FIELD_S_H(state->words[0]) == REG_LIMM))
 			state->instr_len += 4;
 		break;

 	case op_S:
 		subopcode = BITS(state->words[0], 5, 7);
 		switch (subopcode) {
 		case 0:	/* j_s */
 		case 1:	/* j_s.d */
 		case 2:	/* jl_s */
 		case 3:	/* jl_s.d */
 			state->target = get_reg(FIELD_S_B(state->words[0]),
 						regs, cregs);
 			state->delay_slot = subopcode & 1;
 			state->flow = (subopcode >= 2) ?
 				direct_call : indirect_jump;
 			break;
 		case 7:
 			switch (BITS(state->words[0], 8, 10)) {
 			case 4:	/* jeq_s [blink] */
 			case 5:	/* jne_s [blink] */
 			case 6:	/* j_s [blink] */
 			case 7:	/* j_s.d [blink] */
 				state->delay_slot = (subopcode == 7);
 				state->flow = indirect_jump;
 				state->target = get_reg(31, regs, cregs);
 			default:
 				break;
 			}
 		default:
 			break;
 		}
 		break;

 	case op_LD_S:	/* LD_S c, [b, u7] */
 		state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
 		state->src2 = FIELD_S_u7(state->words[0]);
 		state->dest = FIELD_S_C(state->words[0]);
 		break;

 	case op_LDB_S:
 	case op_STB_S:
 		/* no further handling required as byte accesses should not
 		 * cause an unaligned access exception */
 		state->zz = 1;
 		break;

 	case op_LDWX_S:	/* LDWX_S c, [b, u6] */
 		state->x = 1;
 		/* intentional fall-through */

 	case op_LDW_S:	/* LDW_S c, [b, u6] */
 		state->zz = 2;
 		state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
 		state->src2 = FIELD_S_u6(state->words[0]);
 		state->dest = FIELD_S_C(state->words[0]);
 		break;

 	case op_ST_S:	/* ST_S c, [b, u7] */
 		state->write = 1;
 		state->src1 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
 		state->src2 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
 		state->src3 = FIELD_S_u7(state->words[0]);
 		break;

 	case op_STW_S:	/* STW_S c,[b,u6] */
 		state->write = 1;
 		state->zz = 2;
 		state->src1 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
 		state->src2 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
 		state->src3 = FIELD_S_u6(state->words[0]);
 		break;

 	case op_SP:	/* LD_S|LDB_S b,[sp,u7], ST_S|STB_S b,[sp,u7] */
 		/* note: we are ignoring possibility of:
 		 * ADD_S, SUB_S, PUSH_S, POP_S as these should not
 		 * cause unaliged exception anyway */
 		state->write = BITS(state->words[0], 6, 6);
 		state->zz = BITS(state->words[0], 5, 5);
 		if (state->zz)
 			break;	/* byte accesses should not come here */
 		if (!state->write) {
 			state->src1 = get_reg(28, regs, cregs);
 			state->src2 = FIELD_S_u7(state->words[0]);
 			state->dest = FIELD_S_B(state->words[0]);
 		} else {
 			state->src1 = get_reg(FIELD_S_B(state->words[0]), regs,
 					cregs);
 			state->src2 = get_reg(28, regs, cregs);
 			state->src3 = FIELD_S_u7(state->words[0]);
 		}
 		break;

 	case op_GP:	/* LD_S|LDB_S|LDW_S r0,[gp,s11/s9/s10] */
 		/* note: ADD_S r0, gp, s11 is ignored */
 		state->zz = BITS(state->words[0], 9, 10);
 		state->src1 = get_reg(26, regs, cregs);
 		state->src2 = state->zz ? FIELD_S_s10(state->words[0]) :
 			FIELD_S_s11(state->words[0]);
 		state->dest = 0;
 		break;

 	case op_Pcl:	/* LD_S b,[pcl,u10] */
 		state->src1 = regs->ret & ~3;
 		state->src2 = FIELD_S_u10(state->words[0]);
 		state->dest = FIELD_S_B(state->words[0]);
 		break;

 	case op_BR_S:
 		state->target = FIELD_S_s8(state->words[0]) + (addr & ~0x03);
 		state->flow = direct_jump;
 		state->is_branch = 1;
 		break;

 	case op_B_S:
 		fieldA = (BITS(state->words[0], 9, 10) == 3) ?
 			FIELD_S_s7(state->words[0]) :
 			FIELD_S_s10(state->words[0]);
 		state->target = fieldA + (addr & ~0x03);
 		state->flow = direct_jump;
 		state->is_branch = 1;
 		break;

 	case op_BL_S:
 		state->target = FIELD_S_s13(state->words[0]) + (addr & ~0x03);
 		state->flow = direct_call;
 		state->is_branch = 1;
 		break;

 	default:
 		break;
 	}

 	if (bytes_not_copied <= (8 - state->instr_len))
 		return;

 fault:	state->fault = 1;
 }

 long __kprobes get_reg(int reg, struct pt_regs *regs,
 		       struct callee_regs *cregs)
 {
 	long *p;

 	if (reg <= 12) {
 		p = &regs->r0;
 		return p[-reg];
 	}

 	if (cregs && (reg <= 25)) {
 		p = &cregs->r13;
 		return p[13-reg];
 	}

 	if (reg == 26)
 		return regs->r26;
 	if (reg == 27)
 		return regs->fp;
 	if (reg == 28)
 		return regs->sp;
 	if (reg == 31)
 		return regs->blink;

 	return 0;
 }

 void __kprobes set_reg(int reg, long val, struct pt_regs *regs,
 		struct callee_regs *cregs)
 {
 	long *p;

 	switch (reg) {
 	case 0 ... 12:
 		p = &regs->r0;
 		p[-reg] = val;
 		break;
 	case 13 ... 25:
 		if (cregs) {
 			p = &cregs->r13;
 			p[13-reg] = val;
 		}
 		break;
 	case 26:
 		regs->r26 = val;
 		break;
 	case 27:
 		regs->fp = val;
 		break;
 	case 28:
 		regs->sp = val;
 		break;
 	case 31:
 		regs->blink = val;
 		break;
 	default:
 		break;
 	}
 }

 /*
  * Disassembles the insn at @pc and sets @next_pc to next PC (which could be
  * @pc +2/4/6 (ARCompact ISA allows free intermixing of 16/32 bit insns).
  *
  * If @pc is a branch
  *	-@tgt_if_br is set to branch target.
  *	-If branch has delay slot, @next_pc updated with actual next PC.
  */
 int __kprobes disasm_next_pc(unsigned long pc, struct pt_regs *regs,
 			     struct callee_regs *cregs,
 			     unsigned long *next_pc, unsigned long *tgt_if_br)
 {
 	struct disasm_state instr;

 	memset(&instr, 0, sizeof(struct disasm_state));
 	disasm_instr(pc, &instr, 0, regs, cregs);

 	*next_pc = pc + instr.instr_len;

 	/* Instruction with possible two targets branch, jump and loop */
 	if (instr.is_branch)
 		*tgt_if_br = instr.target;

 	/* For the instructions with delay slots, the fall through is the
 	 * instruction following the instruction in delay slot.
 	 */
 	 if (instr.delay_slot) {
 		struct disasm_state instr_d;

 		disasm_instr(*next_pc, &instr_d, 0, regs, cregs);

 		*next_pc += instr_d.instr_len;
 	 }

 	 /* Zero Overhead Loop - end of the loop */
 	if (!(regs->status32 & STATUS32_L) && (*next_pc == regs->lp_end)
 		&& (regs->lp_count > 1)) {
 		*next_pc = regs->lp_start;
 	}

 	return instr.is_branch;
 }

 #endif /* CONFIG_KGDB || CONFIG_ARC_MISALIGN_ACCESS || CONFIG_KPROBES */
	/*
	* several functions that help interpret ARC instructions
	* used for unaligned accesses, kprobes and kgdb
	*
	* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/types.h>
	#include <linux/kprobes.h>
	#include <linux/slab.h>
	#include <linux/uaccess.h>
	#include <asm/disasm.h>

	#if defined(CONFIG_KGDB) \|\| defined(CONFIG_ARC_MISALIGN_ACCESS) \|\| \
	defined(CONFIG_KPROBES)

	/* disasm_instr: Analyses instruction at addr, stores
	* findings in *state
	*/
	void __kprobes disasm_instr(unsigned long addr, struct disasm_state *state,
	int userspace, struct pt_regs regs, struct callee_regs cregs)
	{
	int fieldA = 0;
	int fieldC = 0, fieldCisReg = 0;
	uint16_t word1 = 0, word0 = 0;
	int subopcode, is_linked, op_format;
	uint16_t *ins_ptr;
	uint16_t ins_buf[4];
	int bytes_not_copied = 0;

	memset(state, 0, sizeof(struct disasm_state));

	/* This fetches the upper part of the 32 bit instruction
	* in both the cases of Little Endian or Big Endian configurations. */
	if (userspace) {
	bytes_not_copied = copy_from_user(ins_buf,
	(const void __user *) addr, 8);
	if (bytes_not_copied > 6)
	goto fault;
	ins_ptr = ins_buf;
	} else {
	ins_ptr = (uint16_t *) addr;
	}

	word1 = ((uint16_t )addr);

	state->major_opcode = (word1 >> 11) & 0x1F;

	/* Check if the instruction is 32 bit or 16 bit instruction */
	if (state->major_opcode < 0x0B) {
	if (bytes_not_copied > 4)
	goto fault;
	state->instr_len = 4;
	word0 = ((uint16_t )(addr+2));
	state->words[0] = (word1 << 16) \| word0;
	} else {
	state->instr_len = 2;
	state->words[0] = word1;
	}

	/* Read the second word in case of limm */
	word1 = ((uint16_t )(addr + state->instr_len));
	word0 = ((uint16_t )(addr + state->instr_len + 2));
	state->words[1] = (word1 << 16) \| word0;

	switch (state->major_opcode) {
	case op_Bcc:
	state->is_branch = 1;

	/* unconditional branch s25, conditional branch s21 */
	fieldA = (IS_BIT(state->words[0], 16)) ?
	FIELD_s25(state->words[0]) :
	FIELD_s21(state->words[0]);

	state->delay_slot = IS_BIT(state->words[0], 5);
	state->target = fieldA + (addr & ~0x3);
	state->flow = direct_jump;
	break;

	case op_BLcc:
	if (IS_BIT(state->words[0], 16)) {
	/* Branch and Link*/
	/* unconditional branch s25, conditional branch s21 */
	fieldA = (IS_BIT(state->words[0], 17)) ?
	(FIELD_s25(state->words[0]) & ~0x3) :
	FIELD_s21(state->words[0]);

	state->flow = direct_call;
	} else {
	/Branch On Compare /
	fieldA = FIELD_s9(state->words[0]) & ~0x3;
	state->flow = direct_jump;
	}

	state->delay_slot = IS_BIT(state->words[0], 5);
	state->target = fieldA + (addr & ~0x3);
	state->is_branch = 1;
	break;

	case op_LD: /* LD<zz> a,[b,s9] */
	state->write = 0;
	state->di = BITS(state->words[0], 11, 11);
	if (state->di)
	break;
	state->x = BITS(state->words[0], 6, 6);
	state->zz = BITS(state->words[0], 7, 8);
	state->aa = BITS(state->words[0], 9, 10);
	state->wb_reg = FIELD_B(state->words[0]);
	if (state->wb_reg == REG_LIMM) {
	state->instr_len += 4;
	state->aa = 0;
	state->src1 = state->words[1];
	} else {
	state->src1 = get_reg(state->wb_reg, regs, cregs);
	}
	state->src2 = FIELD_s9(state->words[0]);
	state->dest = FIELD_A(state->words[0]);
	state->pref = (state->dest == REG_LIMM);
	break;

	case op_ST:
	state->write = 1;
	state->di = BITS(state->words[0], 5, 5);
	if (state->di)
	break;
	state->aa = BITS(state->words[0], 3, 4);
	state->zz = BITS(state->words[0], 1, 2);
	state->src1 = FIELD_C(state->words[0]);
	if (state->src1 == REG_LIMM) {
	state->instr_len += 4;
	state->src1 = state->words[1];
	} else {
	state->src1 = get_reg(state->src1, regs, cregs);
	}
	state->wb_reg = FIELD_B(state->words[0]);
	if (state->wb_reg == REG_LIMM) {
	state->aa = 0;
	state->instr_len += 4;
	state->src2 = state->words[1];
	} else {
	state->src2 = get_reg(state->wb_reg, regs, cregs);
	}
	state->src3 = FIELD_s9(state->words[0]);
	break;

	case op_MAJOR_4:
	subopcode = MINOR_OPCODE(state->words[0]);
	switch (subopcode) {
	case 32: /* Jcc */
	case 33: /* Jcc.D */
	case 34: /* JLcc */
	case 35: /* JLcc.D */
	is_linked = 0;

	if (subopcode == 33 \|\| subopcode == 35)
	state->delay_slot = 1;

	if (subopcode == 34 \|\| subopcode == 35)
	is_linked = 1;

	fieldCisReg = 0;
	op_format = BITS(state->words[0], 22, 23);
	if (op_format == 0 \|\| ((op_format == 3) &&
	(!IS_BIT(state->words[0], 5)))) {
	fieldC = FIELD_C(state->words[0]);

	if (fieldC == REG_LIMM) {
	fieldC = state->words[1];
	state->instr_len += 4;
	} else {
	fieldCisReg = 1;
	}
	} else if (op_format == 1 \|\| ((op_format == 3)
	&& (IS_BIT(state->words[0], 5)))) {
	fieldC = FIELD_C(state->words[0]);
	} else {
	/* op_format == 2 */
	fieldC = FIELD_s12(state->words[0]);
	}

	if (!fieldCisReg) {
	state->target = fieldC;
	state->flow = is_linked ?
	direct_call : direct_jump;
	} else {
	state->target = get_reg(fieldC, regs, cregs);
	state->flow = is_linked ?
	indirect_call : indirect_jump;
	}
	state->is_branch = 1;
	break;

	case 40: /* LPcc */
	if (BITS(state->words[0], 22, 23) == 3) {
	/* Conditional LPcc u7 */
	fieldC = FIELD_C(state->words[0]);

	fieldC = fieldC << 1;
	fieldC += (addr & ~0x03);
	state->is_branch = 1;
	state->flow = direct_jump;
	state->target = fieldC;
	}
	/* For Unconditional lp, next pc is the fall through
	* which is updated */
	break;

	case 48 ... 55: /* LD a,[b,c] */
	state->di = BITS(state->words[0], 15, 15);
	if (state->di)
	break;
	state->x = BITS(state->words[0], 16, 16);
	state->zz = BITS(state->words[0], 17, 18);
	state->aa = BITS(state->words[0], 22, 23);
	state->wb_reg = FIELD_B(state->words[0]);
	if (state->wb_reg == REG_LIMM) {
	state->instr_len += 4;
	state->src1 = state->words[1];
	} else {
	state->src1 = get_reg(state->wb_reg, regs,
	cregs);
	}
	state->src2 = FIELD_C(state->words[0]);
	if (state->src2 == REG_LIMM) {
	state->instr_len += 4;
	state->src2 = state->words[1];
	} else {
	state->src2 = get_reg(state->src2, regs,
	cregs);
	}
	state->dest = FIELD_A(state->words[0]);
	if (state->dest == REG_LIMM)
	state->pref = 1;
	break;

	case 10: /* MOV */
	/* still need to check for limm to extract instr len */
	/* MOV is special case because it only takes 2 args */
	switch (BITS(state->words[0], 22, 23)) {
	case 0: /* OP a,b,c */
	if (FIELD_C(state->words[0]) == REG_LIMM)
	state->instr_len += 4;
	break;
	case 1: /* OP a,b,u6 */
	break;
	case 2: /* OP b,b,s12 */
	break;
	case 3: /* OP.cc b,b,c/u6 */
	if ((!IS_BIT(state->words[0], 5)) &&
	(FIELD_C(state->words[0]) == REG_LIMM))
	state->instr_len += 4;
	break;
	}
	break;


	default:
	/* Not a Load, Jump or Loop instruction */
	/* still need to check for limm to extract instr len */
	switch (BITS(state->words[0], 22, 23)) {
	case 0: /* OP a,b,c */
	if ((FIELD_B(state->words[0]) == REG_LIMM) \|\|
	(FIELD_C(state->words[0]) == REG_LIMM))
	state->instr_len += 4;
	break;
	case 1: /* OP a,b,u6 */
	break;
	case 2: /* OP b,b,s12 */
	break;
	case 3: /* OP.cc b,b,c/u6 */
	if ((!IS_BIT(state->words[0], 5)) &&
	((FIELD_B(state->words[0]) == REG_LIMM) \|\|
	(FIELD_C(state->words[0]) == REG_LIMM)))
	state->instr_len += 4;
	break;
	}
	break;
	}
	break;

	/* 16 Bit Instructions */
	case op_LD_ADD: /* LD_S\|LDB_S\|LDW_S a,[b,c] */
	state->zz = BITS(state->words[0], 3, 4);
	state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
	state->src2 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
	state->dest = FIELD_S_A(state->words[0]);
	break;

	case op_ADD_MOV_CMP:
	/* check for limm, ignore mov_s h,b (== mov_s 0,b) */
	if ((BITS(state->words[0], 3, 4) < 3) &&
	(FIELD_S_H(state->words[0]) == REG_LIMM))
	state->instr_len += 4;
	break;

	case op_S:
	subopcode = BITS(state->words[0], 5, 7);
	switch (subopcode) {
	case 0: /* j_s */
	case 1: /* j_s.d */
	case 2: /* jl_s */
	case 3: /* jl_s.d */
	state->target = get_reg(FIELD_S_B(state->words[0]),
	regs, cregs);
	state->delay_slot = subopcode & 1;
	state->flow = (subopcode >= 2) ?
	direct_call : indirect_jump;
	break;
	case 7:
	switch (BITS(state->words[0], 8, 10)) {
	case 4: /* jeq_s [blink] */
	case 5: /* jne_s [blink] */
	case 6: /* j_s [blink] */
	case 7: /* j_s.d [blink] */
	state->delay_slot = (subopcode == 7);
	state->flow = indirect_jump;
	state->target = get_reg(31, regs, cregs);
	default:
	break;
	}
	default:
	break;
	}
	break;

	case op_LD_S: /* LD_S c, [b, u7] */
	state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
	state->src2 = FIELD_S_u7(state->words[0]);
	state->dest = FIELD_S_C(state->words[0]);
	break;

	case op_LDB_S:
	case op_STB_S:
	/* no further handling required as byte accesses should not
	* cause an unaligned access exception */
	state->zz = 1;
	break;

	case op_LDWX_S: /* LDWX_S c, [b, u6] */
	state->x = 1;
	/* intentional fall-through */

	case op_LDW_S: /* LDW_S c, [b, u6] */
	state->zz = 2;
	state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
	state->src2 = FIELD_S_u6(state->words[0]);
	state->dest = FIELD_S_C(state->words[0]);
	break;

	case op_ST_S: /* ST_S c, [b, u7] */
	state->write = 1;
	state->src1 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
	state->src2 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
	state->src3 = FIELD_S_u7(state->words[0]);
	break;

	case op_STW_S: /* STW_S c,[b,u6] */
	state->write = 1;
	state->zz = 2;
	state->src1 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
	state->src2 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
	state->src3 = FIELD_S_u6(state->words[0]);
	break;

	case op_SP: /* LD_S\|LDB_S b,[sp,u7], ST_S\|STB_S b,[sp,u7] */
	/* note: we are ignoring possibility of:
	* ADD_S, SUB_S, PUSH_S, POP_S as these should not
	* cause unaliged exception anyway */
	state->write = BITS(state->words[0], 6, 6);
	state->zz = BITS(state->words[0], 5, 5);
	if (state->zz)
	break; /* byte accesses should not come here */
	if (!state->write) {
	state->src1 = get_reg(28, regs, cregs);
	state->src2 = FIELD_S_u7(state->words[0]);
	state->dest = FIELD_S_B(state->words[0]);
	} else {
	state->src1 = get_reg(FIELD_S_B(state->words[0]), regs,
	cregs);
	state->src2 = get_reg(28, regs, cregs);
	state->src3 = FIELD_S_u7(state->words[0]);
	}
	break;

	case op_GP: /* LD_S\|LDB_S\|LDW_S r0,[gp,s11/s9/s10] */
	/* note: ADD_S r0, gp, s11 is ignored */
	state->zz = BITS(state->words[0], 9, 10);
	state->src1 = get_reg(26, regs, cregs);
	state->src2 = state->zz ? FIELD_S_s10(state->words[0]) :
	FIELD_S_s11(state->words[0]);
	state->dest = 0;
	break;

	case op_Pcl: /* LD_S b,[pcl,u10] */
	state->src1 = regs->ret & ~3;
	state->src2 = FIELD_S_u10(state->words[0]);
	state->dest = FIELD_S_B(state->words[0]);
	break;

	case op_BR_S:
	state->target = FIELD_S_s8(state->words[0]) + (addr & ~0x03);
	state->flow = direct_jump;
	state->is_branch = 1;
	break;

	case op_B_S:
	fieldA = (BITS(state->words[0], 9, 10) == 3) ?
	FIELD_S_s7(state->words[0]) :
	FIELD_S_s10(state->words[0]);
	state->target = fieldA + (addr & ~0x03);
	state->flow = direct_jump;
	state->is_branch = 1;
	break;

	case op_BL_S:
	state->target = FIELD_S_s13(state->words[0]) + (addr & ~0x03);
	state->flow = direct_call;
	state->is_branch = 1;
	break;

	default:
	break;
	}

	if (bytes_not_copied <= (8 - state->instr_len))
	return;

	fault: state->fault = 1;
	}

	long __kprobes get_reg(int reg, struct pt_regs *regs,
	struct callee_regs *cregs)
	{
	long *p;

	if (reg <= 12) {
	p = &regs->r0;
	return p[-reg];
	}

	if (cregs && (reg <= 25)) {
	p = &cregs->r13;
	return p[13-reg];
	}

	if (reg == 26)
	return regs->r26;
	if (reg == 27)
	return regs->fp;
	if (reg == 28)
	return regs->sp;
	if (reg == 31)
	return regs->blink;

	return 0;
	}

	void __kprobes set_reg(int reg, long val, struct pt_regs *regs,
	struct callee_regs *cregs)
	{
	long *p;

	switch (reg) {
	case 0 ... 12:
	p = &regs->r0;
	p[-reg] = val;
	break;
	case 13 ... 25:
	if (cregs) {
	p = &cregs->r13;
	p[13-reg] = val;
	}
	break;
	case 26:
	regs->r26 = val;
	break;
	case 27:
	regs->fp = val;
	break;
	case 28:
	regs->sp = val;
	break;
	case 31:
	regs->blink = val;
	break;
	default:
	break;
	}
	}

	/*
	* Disassembles the insn at @pc and sets @next_pc to next PC (which could be
	* @pc +2/4/6 (ARCompact ISA allows free intermixing of 16/32 bit insns).
	*
	* If @pc is a branch
	* -@tgt_if_br is set to branch target.
	* -If branch has delay slot, @next_pc updated with actual next PC.
	*/
	int __kprobes disasm_next_pc(unsigned long pc, struct pt_regs *regs,
	struct callee_regs *cregs,
	unsigned long next_pc, unsigned long tgt_if_br)
	{
	struct disasm_state instr;

	memset(&instr, 0, sizeof(struct disasm_state));
	disasm_instr(pc, &instr, 0, regs, cregs);

	*next_pc = pc + instr.instr_len;

	/* Instruction with possible two targets branch, jump and loop */
	if (instr.is_branch)
	*tgt_if_br = instr.target;

	/* For the instructions with delay slots, the fall through is the
	* instruction following the instruction in delay slot.
	*/
	if (instr.delay_slot) {
	struct disasm_state instr_d;

	disasm_instr(*next_pc, &instr_d, 0, regs, cregs);

	*next_pc += instr_d.instr_len;
	}

	/* Zero Overhead Loop - end of the loop */
	if (!(regs->status32 & STATUS32_L) && (*next_pc == regs->lp_end)
	&& (regs->lp_count > 1)) {
	*next_pc = regs->lp_start;
	}

	return instr.is_branch;
	}

	#endif /* CONFIG_KGDB \|\| CONFIG_ARC_MISALIGN_ACCESS \|\| CONFIG_KPROBES */