[deliverable/linux.git] / arch / mips / math-emu / cp1emu.c

/*
 * cp1emu.c: a MIPS coprocessor 1 (FPU) instruction emulator
 *
 * MIPS floating point support
 * Copyright (C) 1994-2000 Algorithmics Ltd.
 *
 * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 2000  MIPS Technologies, Inc.
 *
 *  This program is free software; you can distribute it and/or modify it
 *  under the terms of the GNU General Public License (Version 2) as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
 *
 * A complete emulator for MIPS coprocessor 1 instructions.  This is
 * required for #float(switch) or #float(trap), where it catches all
 * COP1 instructions via the "CoProcessor Unusable" exception.
 *
 * More surprisingly it is also required for #float(ieee), to help out
 * the hardware FPU at the boundaries of the IEEE-754 representation
 * (denormalised values, infinities, underflow, etc).  It is made
 * quite nasty because emulation of some non-COP1 instructions is
 * required, e.g. in branch delay slots.
 *
 * Note if you know that you won't have an FPU, then you'll get much
 * better performance by compiling with -msoft-float!
 */
#include <linux/sched.h>
#include <linux/debugfs.h>
#include <linux/kconfig.h>
#include <linux/percpu-defs.h>
#include <linux/perf_event.h>

#include <asm/branch.h>
#include <asm/inst.h>
#include <asm/ptrace.h>
#include <asm/signal.h>
#include <asm/uaccess.h>

#include <asm/processor.h>
#include <asm/fpu_emulator.h>
#include <asm/fpu.h>
#include <asm/mips-r2-to-r6-emul.h>

#include "ieee754.h"

/* Function which emulates a floating point instruction. */

static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
	mips_instruction);

static int fpux_emu(struct pt_regs *,
	struct mips_fpu_struct *, mips_instruction, void *__user *);

/* Control registers */

#define FPCREG_RID	0	/* $0  = revision id */
#define FPCREG_CSR	31	/* $31 = csr */

/* convert condition code register number to csr bit */
const unsigned int fpucondbit[8] = {
	FPU_CSR_COND0,
	FPU_CSR_COND1,
	FPU_CSR_COND2,
	FPU_CSR_COND3,
	FPU_CSR_COND4,
	FPU_CSR_COND5,
	FPU_CSR_COND6,
	FPU_CSR_COND7
};

/* (microMIPS) Convert certain microMIPS instructions to MIPS32 format. */
static const int sd_format[] = {16, 17, 0, 0, 0, 0, 0, 0};
static const int sdps_format[] = {16, 17, 22, 0, 0, 0, 0, 0};
static const int dwl_format[] = {17, 20, 21, 0, 0, 0, 0, 0};
static const int swl_format[] = {16, 20, 21, 0, 0, 0, 0, 0};

/*
 * This functions translates a 32-bit microMIPS instruction
 * into a 32-bit MIPS32 instruction. Returns 0 on success
 * and SIGILL otherwise.
 */
static int microMIPS32_to_MIPS32(union mips_instruction *insn_ptr)
{
	union mips_instruction insn = *insn_ptr;
	union mips_instruction mips32_insn = insn;
	int func, fmt, op;

	switch (insn.mm_i_format.opcode) {
	case mm_ldc132_op:
		mips32_insn.mm_i_format.opcode = ldc1_op;
		mips32_insn.mm_i_format.rt = insn.mm_i_format.rs;
		mips32_insn.mm_i_format.rs = insn.mm_i_format.rt;
		break;
	case mm_lwc132_op:
		mips32_insn.mm_i_format.opcode = lwc1_op;
		mips32_insn.mm_i_format.rt = insn.mm_i_format.rs;
		mips32_insn.mm_i_format.rs = insn.mm_i_format.rt;
		break;
	case mm_sdc132_op:
		mips32_insn.mm_i_format.opcode = sdc1_op;
		mips32_insn.mm_i_format.rt = insn.mm_i_format.rs;
		mips32_insn.mm_i_format.rs = insn.mm_i_format.rt;
		break;
	case mm_swc132_op:
		mips32_insn.mm_i_format.opcode = swc1_op;
		mips32_insn.mm_i_format.rt = insn.mm_i_format.rs;
		mips32_insn.mm_i_format.rs = insn.mm_i_format.rt;
		break;
	case mm_pool32i_op:
		/* NOTE: offset is << by 1 if in microMIPS mode. */
		if ((insn.mm_i_format.rt == mm_bc1f_op) ||
		    (insn.mm_i_format.rt == mm_bc1t_op)) {
			mips32_insn.fb_format.opcode = cop1_op;
			mips32_insn.fb_format.bc = bc_op;
			mips32_insn.fb_format.flag =
				(insn.mm_i_format.rt == mm_bc1t_op) ? 1 : 0;
		} else
			return SIGILL;
		break;
	case mm_pool32f_op:
		switch (insn.mm_fp0_format.func) {
		case mm_32f_01_op:
		case mm_32f_11_op:
		case mm_32f_02_op:
		case mm_32f_12_op:
		case mm_32f_41_op:
		case mm_32f_51_op:
		case mm_32f_42_op:
		case mm_32f_52_op:
			op = insn.mm_fp0_format.func;
			if (op == mm_32f_01_op)
				func = madd_s_op;
			else if (op == mm_32f_11_op)
				func = madd_d_op;
			else if (op == mm_32f_02_op)
				func = nmadd_s_op;
			else if (op == mm_32f_12_op)
				func = nmadd_d_op;
			else if (op == mm_32f_41_op)
				func = msub_s_op;
			else if (op == mm_32f_51_op)
				func = msub_d_op;
			else if (op == mm_32f_42_op)
				func = nmsub_s_op;
			else
				func = nmsub_d_op;
			mips32_insn.fp6_format.opcode = cop1x_op;
			mips32_insn.fp6_format.fr = insn.mm_fp6_format.fr;
			mips32_insn.fp6_format.ft = insn.mm_fp6_format.ft;
			mips32_insn.fp6_format.fs = insn.mm_fp6_format.fs;
			mips32_insn.fp6_format.fd = insn.mm_fp6_format.fd;
			mips32_insn.fp6_format.func = func;
			break;
		case mm_32f_10_op:
			func = -1;	/* Invalid */
			op = insn.mm_fp5_format.op & 0x7;
			if (op == mm_ldxc1_op)
				func = ldxc1_op;
			else if (op == mm_sdxc1_op)
				func = sdxc1_op;
			else if (op == mm_lwxc1_op)
				func = lwxc1_op;
			else if (op == mm_swxc1_op)
				func = swxc1_op;

			if (func != -1) {
				mips32_insn.r_format.opcode = cop1x_op;
				mips32_insn.r_format.rs =
					insn.mm_fp5_format.base;
				mips32_insn.r_format.rt =
					insn.mm_fp5_format.index;
				mips32_insn.r_format.rd = 0;
				mips32_insn.r_format.re = insn.mm_fp5_format.fd;
				mips32_insn.r_format.func = func;
			} else
				return SIGILL;
			break;
		case mm_32f_40_op:
			op = -1;	/* Invalid */
			if (insn.mm_fp2_format.op == mm_fmovt_op)
				op = 1;
			else if (insn.mm_fp2_format.op == mm_fmovf_op)
				op = 0;
			if (op != -1) {
				mips32_insn.fp0_format.opcode = cop1_op;
				mips32_insn.fp0_format.fmt =
					sdps_format[insn.mm_fp2_format.fmt];
				mips32_insn.fp0_format.ft =
					(insn.mm_fp2_format.cc<<2) + op;
				mips32_insn.fp0_format.fs =
					insn.mm_fp2_format.fs;
				mips32_insn.fp0_format.fd =
					insn.mm_fp2_format.fd;
				mips32_insn.fp0_format.func = fmovc_op;
			} else
				return SIGILL;
			break;
		case mm_32f_60_op:
			func = -1;	/* Invalid */
			if (insn.mm_fp0_format.op == mm_fadd_op)
				func = fadd_op;
			else if (insn.mm_fp0_format.op == mm_fsub_op)
				func = fsub_op;
			else if (insn.mm_fp0_format.op == mm_fmul_op)
				func = fmul_op;
			else if (insn.mm_fp0_format.op == mm_fdiv_op)
				func = fdiv_op;
			if (func != -1) {
				mips32_insn.fp0_format.opcode = cop1_op;
				mips32_insn.fp0_format.fmt =
					sdps_format[insn.mm_fp0_format.fmt];
				mips32_insn.fp0_format.ft =
					insn.mm_fp0_format.ft;
				mips32_insn.fp0_format.fs =
					insn.mm_fp0_format.fs;
				mips32_insn.fp0_format.fd =
					insn.mm_fp0_format.fd;
				mips32_insn.fp0_format.func = func;
			} else
				return SIGILL;
			break;
		case mm_32f_70_op:
			func = -1;	/* Invalid */
			if (insn.mm_fp0_format.op == mm_fmovn_op)
				func = fmovn_op;
			else if (insn.mm_fp0_format.op == mm_fmovz_op)
				func = fmovz_op;
			if (func != -1) {
				mips32_insn.fp0_format.opcode = cop1_op;
				mips32_insn.fp0_format.fmt =
					sdps_format[insn.mm_fp0_format.fmt];
				mips32_insn.fp0_format.ft =
					insn.mm_fp0_format.ft;
				mips32_insn.fp0_format.fs =
					insn.mm_fp0_format.fs;
				mips32_insn.fp0_format.fd =
					insn.mm_fp0_format.fd;
				mips32_insn.fp0_format.func = func;
			} else
				return SIGILL;
			break;
		case mm_32f_73_op:    /* POOL32FXF */
			switch (insn.mm_fp1_format.op) {
			case mm_movf0_op:
			case mm_movf1_op:
			case mm_movt0_op:
			case mm_movt1_op:
				if ((insn.mm_fp1_format.op & 0x7f) ==
				    mm_movf0_op)
					op = 0;
				else
					op = 1;
				mips32_insn.r_format.opcode = spec_op;
				mips32_insn.r_format.rs = insn.mm_fp4_format.fs;
				mips32_insn.r_format.rt =
					(insn.mm_fp4_format.cc << 2) + op;
				mips32_insn.r_format.rd = insn.mm_fp4_format.rt;
				mips32_insn.r_format.re = 0;
				mips32_insn.r_format.func = movc_op;
				break;
			case mm_fcvtd0_op:
			case mm_fcvtd1_op:
			case mm_fcvts0_op:
			case mm_fcvts1_op:
				if ((insn.mm_fp1_format.op & 0x7f) ==
				    mm_fcvtd0_op) {
					func = fcvtd_op;
					fmt = swl_format[insn.mm_fp3_format.fmt];
				} else {
					func = fcvts_op;
					fmt = dwl_format[insn.mm_fp3_format.fmt];
				}
				mips32_insn.fp0_format.opcode = cop1_op;
				mips32_insn.fp0_format.fmt = fmt;
				mips32_insn.fp0_format.ft = 0;
				mips32_insn.fp0_format.fs =
					insn.mm_fp3_format.fs;
				mips32_insn.fp0_format.fd =
					insn.mm_fp3_format.rt;
				mips32_insn.fp0_format.func = func;
				break;
			case mm_fmov0_op:
			case mm_fmov1_op:
			case mm_fabs0_op:
			case mm_fabs1_op:
			case mm_fneg0_op:
			case mm_fneg1_op:
				if ((insn.mm_fp1_format.op & 0x7f) ==
				    mm_fmov0_op)
					func = fmov_op;
				else if ((insn.mm_fp1_format.op & 0x7f) ==
					 mm_fabs0_op)
					func = fabs_op;
				else
					func = fneg_op;
				mips32_insn.fp0_format.opcode = cop1_op;
				mips32_insn.fp0_format.fmt =
					sdps_format[insn.mm_fp3_format.fmt];
				mips32_insn.fp0_format.ft = 0;
				mips32_insn.fp0_format.fs =
					insn.mm_fp3_format.fs;
				mips32_insn.fp0_format.fd =
					insn.mm_fp3_format.rt;
				mips32_insn.fp0_format.func = func;
				break;
			case mm_ffloorl_op:
			case mm_ffloorw_op:
			case mm_fceill_op:
			case mm_fceilw_op:
			case mm_ftruncl_op:
			case mm_ftruncw_op:
			case mm_froundl_op:
			case mm_froundw_op:
			case mm_fcvtl_op:
			case mm_fcvtw_op:
				if (insn.mm_fp1_format.op == mm_ffloorl_op)
					func = ffloorl_op;
				else if (insn.mm_fp1_format.op == mm_ffloorw_op)
					func = ffloor_op;
				else if (insn.mm_fp1_format.op == mm_fceill_op)
					func = fceill_op;
				else if (insn.mm_fp1_format.op == mm_fceilw_op)
					func = fceil_op;
				else if (insn.mm_fp1_format.op == mm_ftruncl_op)
					func = ftruncl_op;
				else if (insn.mm_fp1_format.op == mm_ftruncw_op)
					func = ftrunc_op;
				else if (insn.mm_fp1_format.op == mm_froundl_op)
					func = froundl_op;
				else if (insn.mm_fp1_format.op == mm_froundw_op)
					func = fround_op;
				else if (insn.mm_fp1_format.op == mm_fcvtl_op)
					func = fcvtl_op;
				else
					func = fcvtw_op;
				mips32_insn.fp0_format.opcode = cop1_op;
				mips32_insn.fp0_format.fmt =
					sd_format[insn.mm_fp1_format.fmt];
				mips32_insn.fp0_format.ft = 0;
				mips32_insn.fp0_format.fs =
					insn.mm_fp1_format.fs;
				mips32_insn.fp0_format.fd =
					insn.mm_fp1_format.rt;
				mips32_insn.fp0_format.func = func;
				break;
			case mm_frsqrt_op:
			case mm_fsqrt_op:
			case mm_frecip_op:
				if (insn.mm_fp1_format.op == mm_frsqrt_op)
					func = frsqrt_op;
				else if (insn.mm_fp1_format.op == mm_fsqrt_op)
					func = fsqrt_op;
				else
					func = frecip_op;
				mips32_insn.fp0_format.opcode = cop1_op;
				mips32_insn.fp0_format.fmt =
					sdps_format[insn.mm_fp1_format.fmt];
				mips32_insn.fp0_format.ft = 0;
				mips32_insn.fp0_format.fs =
					insn.mm_fp1_format.fs;
				mips32_insn.fp0_format.fd =
					insn.mm_fp1_format.rt;
				mips32_insn.fp0_format.func = func;
				break;
			case mm_mfc1_op:
			case mm_mtc1_op:
			case mm_cfc1_op:
			case mm_ctc1_op:
			case mm_mfhc1_op:
			case mm_mthc1_op:
				if (insn.mm_fp1_format.op == mm_mfc1_op)
					op = mfc_op;
				else if (insn.mm_fp1_format.op == mm_mtc1_op)
					op = mtc_op;
				else if (insn.mm_fp1_format.op == mm_cfc1_op)
					op = cfc_op;
				else if (insn.mm_fp1_format.op == mm_ctc1_op)
					op = ctc_op;
				else if (insn.mm_fp1_format.op == mm_mfhc1_op)
					op = mfhc_op;
				else
					op = mthc_op;
				mips32_insn.fp1_format.opcode = cop1_op;
				mips32_insn.fp1_format.op = op;
				mips32_insn.fp1_format.rt =
					insn.mm_fp1_format.rt;
				mips32_insn.fp1_format.fs =
					insn.mm_fp1_format.fs;
				mips32_insn.fp1_format.fd = 0;
				mips32_insn.fp1_format.func = 0;
				break;
			default:
				return SIGILL;
			}
			break;
		case mm_32f_74_op:	/* c.cond.fmt */
			mips32_insn.fp0_format.opcode = cop1_op;
			mips32_insn.fp0_format.fmt =
				sdps_format[insn.mm_fp4_format.fmt];
			mips32_insn.fp0_format.ft = insn.mm_fp4_format.rt;
			mips32_insn.fp0_format.fs = insn.mm_fp4_format.fs;
			mips32_insn.fp0_format.fd = insn.mm_fp4_format.cc << 2;
			mips32_insn.fp0_format.func =
				insn.mm_fp4_format.cond | MM_MIPS32_COND_FC;
			break;
		default:
			return SIGILL;
		}
		break;
	default:
		return SIGILL;
	}

	*insn_ptr = mips32_insn;
	return 0;
}

/*
 * Redundant with logic already in kernel/branch.c,
 * embedded in compute_return_epc.  At some point,
 * a single subroutine should be used across both
 * modules.
 */
static int isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
			 unsigned long *contpc)
{
	union mips_instruction insn = (union mips_instruction)dec_insn.insn;
	unsigned int fcr31;
	unsigned int bit = 0;

	switch (insn.i_format.opcode) {
	case spec_op:
		switch (insn.r_format.func) {
		case jalr_op:
			regs->regs[insn.r_format.rd] =
				regs->cp0_epc + dec_insn.pc_inc +
				dec_insn.next_pc_inc;
			/* Fall through */
		case jr_op:
			/* For R6, JR already emulated in jalr_op */
			if (NO_R6EMU && insn.r_format.opcode == jr_op)
				break;
			*contpc = regs->regs[insn.r_format.rs];
			return 1;
		}
		break;
	case bcond_op:
		switch (insn.i_format.rt) {
		case bltzal_op:
		case bltzall_op:
			if (NO_R6EMU && (insn.i_format.rs ||
			    insn.i_format.rt == bltzall_op))
				break;

			regs->regs[31] = regs->cp0_epc +
				dec_insn.pc_inc +
				dec_insn.next_pc_inc;
			/* Fall through */
		case bltzl_op:
			if (NO_R6EMU)
				break;
		case bltz_op:
			if ((long)regs->regs[insn.i_format.rs] < 0)
				*contpc = regs->cp0_epc +
					dec_insn.pc_inc +
					(insn.i_format.simmediate << 2);
			else
				*contpc = regs->cp0_epc +
					dec_insn.pc_inc +
					dec_insn.next_pc_inc;
			return 1;
		case bgezal_op:
		case bgezall_op:
			if (NO_R6EMU && (insn.i_format.rs ||
			    insn.i_format.rt == bgezall_op))
				break;

			regs->regs[31] = regs->cp0_epc +
				dec_insn.pc_inc +
				dec_insn.next_pc_inc;
			/* Fall through */
		case bgezl_op:
			if (NO_R6EMU)
				break;
		case bgez_op:
			if ((long)regs->regs[insn.i_format.rs] >= 0)
				*contpc = regs->cp0_epc +
					dec_insn.pc_inc +
					(insn.i_format.simmediate << 2);
			else
				*contpc = regs->cp0_epc +
					dec_insn.pc_inc +
					dec_insn.next_pc_inc;
			return 1;
		}
		break;
	case jalx_op:
		set_isa16_mode(bit);
	case jal_op:
		regs->regs[31] = regs->cp0_epc +
			dec_insn.pc_inc +
			dec_insn.next_pc_inc;
		/* Fall through */
	case j_op:
		*contpc = regs->cp0_epc + dec_insn.pc_inc;
		*contpc >>= 28;
		*contpc <<= 28;
		*contpc |= (insn.j_format.target << 2);
		/* Set microMIPS mode bit: XOR for jalx. */
		*contpc ^= bit;
		return 1;
	case beql_op:
		if (NO_R6EMU)
			break;
	case beq_op:
		if (regs->regs[insn.i_format.rs] ==
		    regs->regs[insn.i_format.rt])
			*contpc = regs->cp0_epc +
				dec_insn.pc_inc +
				(insn.i_format.simmediate << 2);
		else
			*contpc = regs->cp0_epc +
				dec_insn.pc_inc +
				dec_insn.next_pc_inc;
		return 1;
	case bnel_op:
		if (NO_R6EMU)
			break;
	case bne_op:
		if (regs->regs[insn.i_format.rs] !=
		    regs->regs[insn.i_format.rt])
			*contpc = regs->cp0_epc +
				dec_insn.pc_inc +
				(insn.i_format.simmediate << 2);
		else
			*contpc = regs->cp0_epc +
				dec_insn.pc_inc +
				dec_insn.next_pc_inc;
		return 1;
	case blezl_op:
		if (NO_R6EMU)
			break;
	case blez_op:

		/*
		 * Compact branches for R6 for the
		 * blez and blezl opcodes.
		 * BLEZ  | rs = 0 | rt != 0  == BLEZALC
		 * BLEZ  | rs = rt != 0      == BGEZALC
		 * BLEZ  | rs != 0 | rt != 0 == BGEUC
		 * BLEZL | rs = 0 | rt != 0  == BLEZC
		 * BLEZL | rs = rt != 0      == BGEZC
		 * BLEZL | rs != 0 | rt != 0 == BGEC
		 *
		 * For real BLEZ{,L}, rt is always 0.
		 */
		if (cpu_has_mips_r6 && insn.i_format.rt) {
			if ((insn.i_format.opcode == blez_op) &&
			    ((!insn.i_format.rs && insn.i_format.rt) ||
			     (insn.i_format.rs == insn.i_format.rt)))
				regs->regs[31] = regs->cp0_epc +
					dec_insn.pc_inc;
			*contpc = regs->cp0_epc + dec_insn.pc_inc +
				dec_insn.next_pc_inc;

			return 1;
		}
		if ((long)regs->regs[insn.i_format.rs] <= 0)
			*contpc = regs->cp0_epc +
				dec_insn.pc_inc +
				(insn.i_format.simmediate << 2);
		else
			*contpc = regs->cp0_epc +
				dec_insn.pc_inc +
				dec_insn.next_pc_inc;
		return 1;
	case bgtzl_op:
		if (NO_R6EMU)
			break;
	case bgtz_op:
		/*
		 * Compact branches for R6 for the
		 * bgtz and bgtzl opcodes.
		 * BGTZ  | rs = 0 | rt != 0  == BGTZALC
		 * BGTZ  | rs = rt != 0      == BLTZALC
		 * BGTZ  | rs != 0 | rt != 0 == BLTUC
		 * BGTZL | rs = 0 | rt != 0  == BGTZC
		 * BGTZL | rs = rt != 0      == BLTZC
		 * BGTZL | rs != 0 | rt != 0 == BLTC
		 *
		 * *ZALC varint for BGTZ &&& rt != 0
		 * For real GTZ{,L}, rt is always 0.
		 */
		if (cpu_has_mips_r6 && insn.i_format.rt) {
			if ((insn.i_format.opcode == blez_op) &&
			    ((!insn.i_format.rs && insn.i_format.rt) ||
			     (insn.i_format.rs == insn.i_format.rt)))
				regs->regs[31] = regs->cp0_epc +
					dec_insn.pc_inc;
			*contpc = regs->cp0_epc + dec_insn.pc_inc +
				dec_insn.next_pc_inc;

			return 1;
		}

		if ((long)regs->regs[insn.i_format.rs] > 0)
			*contpc = regs->cp0_epc +
				dec_insn.pc_inc +
				(insn.i_format.simmediate << 2);
		else
			*contpc = regs->cp0_epc +
				dec_insn.pc_inc +
				dec_insn.next_pc_inc;
		return 1;
	case cbcond0_op:
	case cbcond1_op:
		if (!cpu_has_mips_r6)
			break;
		if (insn.i_format.rt && !insn.i_format.rs)
			regs->regs[31] = regs->cp0_epc + 4;
		*contpc = regs->cp0_epc + dec_insn.pc_inc +
			dec_insn.next_pc_inc;

		return 1;
#ifdef CONFIG_CPU_CAVIUM_OCTEON
	case lwc2_op: /* This is bbit0 on Octeon */
		if ((regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt)) == 0)
			*contpc = regs->cp0_epc + 4 + (insn.i_format.simmediate << 2);
		else
			*contpc = regs->cp0_epc + 8;
		return 1;
	case ldc2_op: /* This is bbit032 on Octeon */
		if ((regs->regs[insn.i_format.rs] & (1ull<<(insn.i_format.rt + 32))) == 0)
			*contpc = regs->cp0_epc + 4 + (insn.i_format.simmediate << 2);
		else
			*contpc = regs->cp0_epc + 8;
		return 1;
	case swc2_op: /* This is bbit1 on Octeon */
		if (regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt))
			*contpc = regs->cp0_epc + 4 + (insn.i_format.simmediate << 2);
		else
			*contpc = regs->cp0_epc + 8;
		return 1;
	case sdc2_op: /* This is bbit132 on Octeon */
		if (regs->regs[insn.i_format.rs] & (1ull<<(insn.i_format.rt + 32)))
			*contpc = regs->cp0_epc + 4 + (insn.i_format.simmediate << 2);
		else
			*contpc = regs->cp0_epc + 8;
		return 1;
#else
	case bc6_op:
		/*
		 * Only valid for MIPS R6 but we can still end up
		 * here from a broken userland so just tell emulator
		 * this is not a branch and let it break later on.
		 */
		if  (!cpu_has_mips_r6)
			break;
		*contpc = regs->cp0_epc + dec_insn.pc_inc +
			dec_insn.next_pc_inc;

		return 1;
	case balc6_op:
		if (!cpu_has_mips_r6)
			break;
		regs->regs[31] = regs->cp0_epc + 4;
		*contpc = regs->cp0_epc + dec_insn.pc_inc +
			dec_insn.next_pc_inc;

		return 1;
	case beqzcjic_op:
		if (!cpu_has_mips_r6)
			break;
		*contpc = regs->cp0_epc + dec_insn.pc_inc +
			dec_insn.next_pc_inc;

		return 1;
	case bnezcjialc_op:
		if (!cpu_has_mips_r6)
			break;
		if (!insn.i_format.rs)
			regs->regs[31] = regs->cp0_epc + 4;
		*contpc = regs->cp0_epc + dec_insn.pc_inc +
			dec_insn.next_pc_inc;

		return 1;
#endif
	case cop0_op:
	case cop1_op:
		/* Need to check for R6 bc1nez and bc1eqz branches */
		if (cpu_has_mips_r6 &&
		    ((insn.i_format.rs == bc1eqz_op) ||
		     (insn.i_format.rs == bc1nez_op))) {
			bit = 0;
			switch (insn.i_format.rs) {
			case bc1eqz_op:
				if (get_fpr32(&current->thread.fpu.fpr[insn.i_format.rt], 0) & 0x1)
				    bit = 1;
				break;
			case bc1nez_op:
				if (!(get_fpr32(&current->thread.fpu.fpr[insn.i_format.rt], 0) & 0x1))
				    bit = 1;
				break;
			}
			if (bit)
				*contpc = regs->cp0_epc +
					dec_insn.pc_inc +
					(insn.i_format.simmediate << 2);
			else
				*contpc = regs->cp0_epc +
					dec_insn.pc_inc +
					dec_insn.next_pc_inc;

			return 1;
		}
		/* R2/R6 compatible cop1 instruction. Fall through */
	case cop2_op:
	case cop1x_op:
		if (insn.i_format.rs == bc_op) {
			preempt_disable();
			if (is_fpu_owner())
			        fcr31 = read_32bit_cp1_register(CP1_STATUS);
			else
				fcr31 = current->thread.fpu.fcr31;
			preempt_enable();

			bit = (insn.i_format.rt >> 2);
			bit += (bit != 0);
			bit += 23;
			switch (insn.i_format.rt & 3) {
			case 0:	/* bc1f */
			case 2:	/* bc1fl */
				if (~fcr31 & (1 << bit))
					*contpc = regs->cp0_epc +
						dec_insn.pc_inc +
						(insn.i_format.simmediate << 2);
				else
					*contpc = regs->cp0_epc +
						dec_insn.pc_inc +
						dec_insn.next_pc_inc;
				return 1;
			case 1:	/* bc1t */
			case 3:	/* bc1tl */
				if (fcr31 & (1 << bit))
					*contpc = regs->cp0_epc +
						dec_insn.pc_inc +
						(insn.i_format.simmediate << 2);
				else
					*contpc = regs->cp0_epc +
						dec_insn.pc_inc +
						dec_insn.next_pc_inc;
				return 1;
			}
		}
		break;
	}
	return 0;
}

/*
 * In the Linux kernel, we support selection of FPR format on the
 * basis of the Status.FR bit.	If an FPU is not present, the FR bit
 * is hardwired to zero, which would imply a 32-bit FPU even for
 * 64-bit CPUs so we rather look at TIF_32BIT_FPREGS.
 * FPU emu is slow and bulky and optimizing this function offers fairly
 * sizeable benefits so we try to be clever and make this function return
 * a constant whenever possible, that is on 64-bit kernels without O32
 * compatibility enabled and on 32-bit without 64-bit FPU support.
 */
static inline int cop1_64bit(struct pt_regs *xcp)
{
	if (config_enabled(CONFIG_64BIT) && !config_enabled(CONFIG_MIPS32_O32))
		return 1;
	else if (config_enabled(CONFIG_32BIT) &&
		 !config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
		return 0;

	return !test_thread_flag(TIF_32BIT_FPREGS);
}

static inline bool hybrid_fprs(void)
{
	return test_thread_flag(TIF_HYBRID_FPREGS);
}

#define SIFROMREG(si, x)						\
do {									\
	if (cop1_64bit(xcp) && !hybrid_fprs())				\
		(si) = (int)get_fpr32(&ctx->fpr[x], 0);			\
	else								\
		(si) = (int)get_fpr32(&ctx->fpr[(x) & ~1], (x) & 1);	\
} while (0)

#define SITOREG(si, x)							\
do {									\
	if (cop1_64bit(xcp) && !hybrid_fprs()) {			\
		unsigned i;						\
		set_fpr32(&ctx->fpr[x], 0, si);				\
		for (i = 1; i < ARRAY_SIZE(ctx->fpr[x].val32); i++)	\
			set_fpr32(&ctx->fpr[x], i, 0);			\
	} else {							\
		set_fpr32(&ctx->fpr[(x) & ~1], (x) & 1, si);		\
	}								\
} while (0)

#define SIFROMHREG(si, x)	((si) = (int)get_fpr32(&ctx->fpr[x], 1))

#define SITOHREG(si, x)							\
do {									\
	unsigned i;							\
	set_fpr32(&ctx->fpr[x], 1, si);					\
	for (i = 2; i < ARRAY_SIZE(ctx->fpr[x].val32); i++)		\
		set_fpr32(&ctx->fpr[x], i, 0);				\
} while (0)

#define DIFROMREG(di, x)						\
	((di) = get_fpr64(&ctx->fpr[(x) & ~(cop1_64bit(xcp) == 0)], 0))

#define DITOREG(di, x)							\
do {									\
	unsigned fpr, i;						\
	fpr = (x) & ~(cop1_64bit(xcp) == 0);				\
	set_fpr64(&ctx->fpr[fpr], 0, di);				\
	for (i = 1; i < ARRAY_SIZE(ctx->fpr[x].val64); i++)		\
		set_fpr64(&ctx->fpr[fpr], i, 0);			\
} while (0)

#define SPFROMREG(sp, x) SIFROMREG((sp).bits, x)
#define SPTOREG(sp, x)	SITOREG((sp).bits, x)
#define DPFROMREG(dp, x)	DIFROMREG((dp).bits, x)
#define DPTOREG(dp, x)	DITOREG((dp).bits, x)

/*
 * Emulate a CFC1 instruction.
 */
static inline void cop1_cfc(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
			    mips_instruction ir)
{
	u32 value;

	if (MIPSInst_RD(ir) == FPCREG_CSR) {
		value = ctx->fcr31;
		pr_debug("%p gpr[%d]<-csr=%08x\n",
			 (void *)xcp->cp0_epc,
			 MIPSInst_RT(ir), value);
	} else if (MIPSInst_RD(ir) == FPCREG_RID)
		value = 0;
	else
		value = 0;
	if (MIPSInst_RT(ir))
		xcp->regs[MIPSInst_RT(ir)] = value;
}

/*
 * Emulate a CTC1 instruction.
 */
static inline void cop1_ctc(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
			    mips_instruction ir)
{
	u32 value;

	if (MIPSInst_RT(ir) == 0)
		value = 0;
	else
		value = xcp->regs[MIPSInst_RT(ir)];

	/* we only have one writable control reg
	 */
	if (MIPSInst_RD(ir) == FPCREG_CSR) {
		pr_debug("%p gpr[%d]->csr=%08x\n",
			 (void *)xcp->cp0_epc,
			 MIPSInst_RT(ir), value);

		/* Don't write reserved bits.  */
		ctx->fcr31 = value & ~FPU_CSR_RSVD;
	}
}

/*
 * Emulate the single floating point instruction pointed at by EPC.
 * Two instructions if the instruction is in a branch delay slot.
 */

static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
		struct mm_decoded_insn dec_insn, void *__user *fault_addr)
{
	unsigned long contpc = xcp->cp0_epc + dec_insn.pc_inc;
	unsigned int cond, cbit;
	mips_instruction ir;
	int likely, pc_inc;
	u32 __user *wva;
	u64 __user *dva;
	u32 wval;
	u64 dval;
	int sig;

	/*
	 * These are giving gcc a gentle hint about what to expect in
	 * dec_inst in order to do better optimization.
	 */
	if (!cpu_has_mmips && dec_insn.micro_mips_mode)
		unreachable();

	/* XXX NEC Vr54xx bug workaround */
	if (delay_slot(xcp)) {
		if (dec_insn.micro_mips_mode) {
			if (!mm_isBranchInstr(xcp, dec_insn, &contpc))
				clear_delay_slot(xcp);
		} else {
			if (!isBranchInstr(xcp, dec_insn, &contpc))
				clear_delay_slot(xcp);
		}
	}

	if (delay_slot(xcp)) {
		/*
		 * The instruction to be emulated is in a branch delay slot
		 * which means that we have to	emulate the branch instruction
		 * BEFORE we do the cop1 instruction.
		 *
		 * This branch could be a COP1 branch, but in that case we
		 * would have had a trap for that instruction, and would not
		 * come through this route.
		 *
		 * Linux MIPS branch emulator operates on context, updating the
		 * cp0_epc.
		 */
		ir = dec_insn.next_insn;  /* process delay slot instr */
		pc_inc = dec_insn.next_pc_inc;
	} else {
		ir = dec_insn.insn;       /* process current instr */
		pc_inc = dec_insn.pc_inc;
	}

	/*
	 * Since microMIPS FPU instructios are a subset of MIPS32 FPU
	 * instructions, we want to convert microMIPS FPU instructions
	 * into MIPS32 instructions so that we could reuse all of the
	 * FPU emulation code.
	 *
	 * NOTE: We cannot do this for branch instructions since they
	 *       are not a subset. Example: Cannot emulate a 16-bit
	 *       aligned target address with a MIPS32 instruction.
	 */
	if (dec_insn.micro_mips_mode) {
		/*
		 * If next instruction is a 16-bit instruction, then it
		 * it cannot be a FPU instruction. This could happen
		 * since we can be called for non-FPU instructions.
		 */
		if ((pc_inc == 2) ||
			(microMIPS32_to_MIPS32((union mips_instruction *)&ir)
			 == SIGILL))
			return SIGILL;
	}

emul:
	perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, xcp, 0);
	MIPS_FPU_EMU_INC_STATS(emulated);
	switch (MIPSInst_OPCODE(ir)) {
	case ldc1_op:
		dva = (u64 __user *) (xcp->regs[MIPSInst_RS(ir)] +
				     MIPSInst_SIMM(ir));
		MIPS_FPU_EMU_INC_STATS(loads);

		if (!access_ok(VERIFY_READ, dva, sizeof(u64))) {
			MIPS_FPU_EMU_INC_STATS(errors);
			*fault_addr = dva;
			return SIGBUS;
		}
		if (__get_user(dval, dva)) {
			MIPS_FPU_EMU_INC_STATS(errors);
			*fault_addr = dva;
			return SIGSEGV;
		}
		DITOREG(dval, MIPSInst_RT(ir));
		break;

	case sdc1_op:
		dva = (u64 __user *) (xcp->regs[MIPSInst_RS(ir)] +
				      MIPSInst_SIMM(ir));
		MIPS_FPU_EMU_INC_STATS(stores);
		DIFROMREG(dval, MIPSInst_RT(ir));
		if (!access_ok(VERIFY_WRITE, dva, sizeof(u64))) {
			MIPS_FPU_EMU_INC_STATS(errors);
			*fault_addr = dva;
			return SIGBUS;
		}
		if (__put_user(dval, dva)) {
			MIPS_FPU_EMU_INC_STATS(errors);
			*fault_addr = dva;
			return SIGSEGV;
		}
		break;

	case lwc1_op:
		wva = (u32 __user *) (xcp->regs[MIPSInst_RS(ir)] +
				      MIPSInst_SIMM(ir));
		MIPS_FPU_EMU_INC_STATS(loads);
		if (!access_ok(VERIFY_READ, wva, sizeof(u32))) {
			MIPS_FPU_EMU_INC_STATS(errors);
			*fault_addr = wva;
			return SIGBUS;
		}
		if (__get_user(wval, wva)) {
			MIPS_FPU_EMU_INC_STATS(errors);
			*fault_addr = wva;
			return SIGSEGV;
		}
		SITOREG(wval, MIPSInst_RT(ir));
		break;

	case swc1_op:
		wva = (u32 __user *) (xcp->regs[MIPSInst_RS(ir)] +
				      MIPSInst_SIMM(ir));
		MIPS_FPU_EMU_INC_STATS(stores);
		SIFROMREG(wval, MIPSInst_RT(ir));
		if (!access_ok(VERIFY_WRITE, wva, sizeof(u32))) {
			MIPS_FPU_EMU_INC_STATS(errors);
			*fault_addr = wva;
			return SIGBUS;
		}
		if (__put_user(wval, wva)) {
			MIPS_FPU_EMU_INC_STATS(errors);
			*fault_addr = wva;
			return SIGSEGV;
		}
		break;

	case cop1_op:
		switch (MIPSInst_RS(ir)) {
		case dmfc_op:
			if (!cpu_has_mips_3_4_5 && !cpu_has_mips64)
				return SIGILL;

			/* copregister fs -> gpr[rt] */
			if (MIPSInst_RT(ir) != 0) {
				DIFROMREG(xcp->regs[MIPSInst_RT(ir)],
					MIPSInst_RD(ir));
			}
			break;

		case dmtc_op:
			if (!cpu_has_mips_3_4_5 && !cpu_has_mips64)
				return SIGILL;

			/* copregister fs <- rt */
			DITOREG(xcp->regs[MIPSInst_RT(ir)], MIPSInst_RD(ir));
			break;

		case mfhc_op:
			if (!cpu_has_mips_r2)
				goto sigill;

			/* copregister rd -> gpr[rt] */
			if (MIPSInst_RT(ir) != 0) {
				SIFROMHREG(xcp->regs[MIPSInst_RT(ir)],
					MIPSInst_RD(ir));
			}
			break;

		case mthc_op:
			if (!cpu_has_mips_r2)
				goto sigill;

			/* copregister rd <- gpr[rt] */
			SITOHREG(xcp->regs[MIPSInst_RT(ir)], MIPSInst_RD(ir));
			break;

		case mfc_op:
			/* copregister rd -> gpr[rt] */
			if (MIPSInst_RT(ir) != 0) {
				SIFROMREG(xcp->regs[MIPSInst_RT(ir)],
					MIPSInst_RD(ir));
			}
			break;

		case mtc_op:
			/* copregister rd <- rt */
			SITOREG(xcp->regs[MIPSInst_RT(ir)], MIPSInst_RD(ir));
			break;

		case cfc_op:
			/* cop control register rd -> gpr[rt] */
			cop1_cfc(xcp, ctx, ir);
			break;

		case ctc_op:
			/* copregister rd <- rt */
			cop1_ctc(xcp, ctx, ir);
			if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
				return SIGFPE;
			}
			break;

		case bc_op:
			if (delay_slot(xcp))
				return SIGILL;

			if (cpu_has_mips_4_5_r)
				cbit = fpucondbit[MIPSInst_RT(ir) >> 2];
			else
				cbit = FPU_CSR_COND;
			cond = ctx->fcr31 & cbit;

			likely = 0;
			switch (MIPSInst_RT(ir) & 3) {
			case bcfl_op:
				if (cpu_has_mips_2_3_4_5_r)
					likely = 1;
				/* Fall through */
			case bcf_op:
				cond = !cond;
				break;
			case bctl_op:
				if (cpu_has_mips_2_3_4_5_r)
					likely = 1;
				/* Fall through */
			case bct_op:
				break;
			}

			set_delay_slot(xcp);
			if (cond) {
				/*
				 * Branch taken: emulate dslot instruction
				 */
				unsigned long bcpc;

				/*
				 * Remember EPC at the branch to point back
				 * at so that any delay-slot instruction
				 * signal is not silently ignored.
				 */
				bcpc = xcp->cp0_epc;
				xcp->cp0_epc += dec_insn.pc_inc;

				contpc = MIPSInst_SIMM(ir);
				ir = dec_insn.next_insn;
				if (dec_insn.micro_mips_mode) {
					contpc = (xcp->cp0_epc + (contpc << 1));

					/* If 16-bit instruction, not FPU. */
					if ((dec_insn.next_pc_inc == 2) ||
						(microMIPS32_to_MIPS32((union mips_instruction *)&ir) == SIGILL)) {

						/*
						 * Since this instruction will
						 * be put on the stack with
						 * 32-bit words, get around
						 * this problem by putting a
						 * NOP16 as the second one.
						 */
						if (dec_insn.next_pc_inc == 2)
							ir = (ir & (~0xffff)) | MM_NOP16;

						/*
						 * Single step the non-CP1
						 * instruction in the dslot.
						 */
						sig = mips_dsemul(xcp, ir,
								  contpc);
						if (sig)
							xcp->cp0_epc = bcpc;
						/*
						 * SIGILL forces out of
						 * the emulation loop.
						 */
						return sig ? sig : SIGILL;
					}
				} else
					contpc = (xcp->cp0_epc + (contpc << 2));

				switch (MIPSInst_OPCODE(ir)) {
				case lwc1_op:
				case swc1_op:
					goto emul;

				case ldc1_op:
				case sdc1_op:
					if (cpu_has_mips_2_3_4_5_r)
						goto emul;

					goto bc_sigill;

				case cop1_op:
					goto emul;

				case cop1x_op:
					if (cpu_has_mips_4_5_64_r2_r6)
						/* its one of ours */
						goto emul;

					goto bc_sigill;

				case spec_op:
					switch (MIPSInst_FUNC(ir)) {
					case movc_op:
						if (cpu_has_mips_4_5_r)
							goto emul;

						goto bc_sigill;
					}
					break;

				bc_sigill:
					xcp->cp0_epc = bcpc;
					return SIGILL;
				}

				/*
				 * Single step the non-cp1
				 * instruction in the dslot
				 */
				sig = mips_dsemul(xcp, ir, contpc);
				if (sig)
					xcp->cp0_epc = bcpc;
				/* SIGILL forces out of the emulation loop.  */
				return sig ? sig : SIGILL;
			} else if (likely) {	/* branch not taken */
				/*
				 * branch likely nullifies
				 * dslot if not taken
				 */
				xcp->cp0_epc += dec_insn.pc_inc;
				contpc += dec_insn.pc_inc;
				/*
				 * else continue & execute
				 * dslot as normal insn
				 */
			}
			break;

		default:
			if (!(MIPSInst_RS(ir) & 0x10))
				return SIGILL;

			/* a real fpu computation instruction */
			if ((sig = fpu_emu(xcp, ctx, ir)))
				return sig;
		}
		break;

	case cop1x_op:
		if (!cpu_has_mips_4_5_64_r2_r6)
			return SIGILL;

		sig = fpux_emu(xcp, ctx, ir, fault_addr);
		if (sig)
			return sig;
		break;

	case spec_op:
		if (!cpu_has_mips_4_5_r)
			return SIGILL;

		if (MIPSInst_FUNC(ir) != movc_op)
			return SIGILL;
		cond = fpucondbit[MIPSInst_RT(ir) >> 2];
		if (((ctx->fcr31 & cond) != 0) == ((MIPSInst_RT(ir) & 1) != 0))
			xcp->regs[MIPSInst_RD(ir)] =
				xcp->regs[MIPSInst_RS(ir)];
		break;
	default:
sigill:
		return SIGILL;
	}

	/* we did it !! */
	xcp->cp0_epc = contpc;
	clear_delay_slot(xcp);

	return 0;
}

/*
 * Conversion table from MIPS compare ops 48-63
 * cond = ieee754dp_cmp(x,y,IEEE754_UN,sig);
 */
static const unsigned char cmptab[8] = {
	0,			/* cmp_0 (sig) cmp_sf */
	IEEE754_CUN,		/* cmp_un (sig) cmp_ngle */
	IEEE754_CEQ,		/* cmp_eq (sig) cmp_seq */
	IEEE754_CEQ | IEEE754_CUN,	/* cmp_ueq (sig) cmp_ngl  */
	IEEE754_CLT,		/* cmp_olt (sig) cmp_lt */
	IEEE754_CLT | IEEE754_CUN,	/* cmp_ult (sig) cmp_nge */
	IEEE754_CLT | IEEE754_CEQ,	/* cmp_ole (sig) cmp_le */
	IEEE754_CLT | IEEE754_CEQ | IEEE754_CUN,	/* cmp_ule (sig) cmp_ngt */
};


/*
 * Additional MIPS4 instructions
 */

#define DEF3OP(name, p, f1, f2, f3)					\
static union ieee754##p fpemu_##p##_##name(union ieee754##p r,		\
	union ieee754##p s, union ieee754##p t)				\
{									\
	struct _ieee754_csr ieee754_csr_save;				\
	s = f1(s, t);							\
	ieee754_csr_save = ieee754_csr;					\
	s = f2(s, r);							\
	ieee754_csr_save.cx |= ieee754_csr.cx;				\
	ieee754_csr_save.sx |= ieee754_csr.sx;				\
	s = f3(s);							\
	ieee754_csr.cx |= ieee754_csr_save.cx;				\
	ieee754_csr.sx |= ieee754_csr_save.sx;				\
	return s;							\
}

static union ieee754dp fpemu_dp_recip(union ieee754dp d)
{
	return ieee754dp_div(ieee754dp_one(0), d);
}

static union ieee754dp fpemu_dp_rsqrt(union ieee754dp d)
{
	return ieee754dp_div(ieee754dp_one(0), ieee754dp_sqrt(d));
}

static union ieee754sp fpemu_sp_recip(union ieee754sp s)
{
	return ieee754sp_div(ieee754sp_one(0), s);
}

static union ieee754sp fpemu_sp_rsqrt(union ieee754sp s)
{
	return ieee754sp_div(ieee754sp_one(0), ieee754sp_sqrt(s));
}

DEF3OP(madd, sp, ieee754sp_mul, ieee754sp_add, );
DEF3OP(msub, sp, ieee754sp_mul, ieee754sp_sub, );
DEF3OP(nmadd, sp, ieee754sp_mul, ieee754sp_add, ieee754sp_neg);
DEF3OP(nmsub, sp, ieee754sp_mul, ieee754sp_sub, ieee754sp_neg);
DEF3OP(madd, dp, ieee754dp_mul, ieee754dp_add, );
DEF3OP(msub, dp, ieee754dp_mul, ieee754dp_sub, );
DEF3OP(nmadd, dp, ieee754dp_mul, ieee754dp_add, ieee754dp_neg);
DEF3OP(nmsub, dp, ieee754dp_mul, ieee754dp_sub, ieee754dp_neg);

static int fpux_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
	mips_instruction ir, void *__user *fault_addr)
{
	unsigned rcsr = 0;	/* resulting csr */

	MIPS_FPU_EMU_INC_STATS(cp1xops);

	switch (MIPSInst_FMA_FFMT(ir)) {
	case s_fmt:{		/* 0 */

		union ieee754sp(*handler) (union ieee754sp, union ieee754sp, union ieee754sp);
		union ieee754sp fd, fr, fs, ft;
		u32 __user *va;
		u32 val;

		switch (MIPSInst_FUNC(ir)) {
		case lwxc1_op:
			va = (void __user *) (xcp->regs[MIPSInst_FR(ir)] +
				xcp->regs[MIPSInst_FT(ir)]);

			MIPS_FPU_EMU_INC_STATS(loads);
			if (!access_ok(VERIFY_READ, va, sizeof(u32))) {
				MIPS_FPU_EMU_INC_STATS(errors);
				*fault_addr = va;
				return SIGBUS;
			}
			if (__get_user(val, va)) {
				MIPS_FPU_EMU_INC_STATS(errors);
				*fault_addr = va;
				return SIGSEGV;
			}
			SITOREG(val, MIPSInst_FD(ir));
			break;

		case swxc1_op:
			va = (void __user *) (xcp->regs[MIPSInst_FR(ir)] +
				xcp->regs[MIPSInst_FT(ir)]);

			MIPS_FPU_EMU_INC_STATS(stores);

			SIFROMREG(val, MIPSInst_FS(ir));
			if (!access_ok(VERIFY_WRITE, va, sizeof(u32))) {
				MIPS_FPU_EMU_INC_STATS(errors);
				*fault_addr = va;
				return SIGBUS;
			}
			if (put_user(val, va)) {
				MIPS_FPU_EMU_INC_STATS(errors);
				*fault_addr = va;
				return SIGSEGV;
			}
			break;

		case madd_s_op:
			handler = fpemu_sp_madd;
			goto scoptop;
		case msub_s_op:
			handler = fpemu_sp_msub;
			goto scoptop;
		case nmadd_s_op:
			handler = fpemu_sp_nmadd;
			goto scoptop;
		case nmsub_s_op:
			handler = fpemu_sp_nmsub;
			goto scoptop;

		      scoptop:
			SPFROMREG(fr, MIPSInst_FR(ir));
			SPFROMREG(fs, MIPSInst_FS(ir));
			SPFROMREG(ft, MIPSInst_FT(ir));
			fd = (*handler) (fr, fs, ft);
			SPTOREG(fd, MIPSInst_FD(ir));

		      copcsr:
			if (ieee754_cxtest(IEEE754_INEXACT)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_inexact);
				rcsr |= FPU_CSR_INE_X | FPU_CSR_INE_S;
			}
			if (ieee754_cxtest(IEEE754_UNDERFLOW)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_underflow);
				rcsr |= FPU_CSR_UDF_X | FPU_CSR_UDF_S;
			}
			if (ieee754_cxtest(IEEE754_OVERFLOW)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_overflow);
				rcsr |= FPU_CSR_OVF_X | FPU_CSR_OVF_S;
			}
			if (ieee754_cxtest(IEEE754_INVALID_OPERATION)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_invalidop);
				rcsr |= FPU_CSR_INV_X | FPU_CSR_INV_S;
			}

			ctx->fcr31 = (ctx->fcr31 & ~FPU_CSR_ALL_X) | rcsr;
			if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
				/*printk ("SIGFPE: FPU csr = %08x\n",
				   ctx->fcr31); */
				return SIGFPE;
			}

			break;

		default:
			return SIGILL;
		}
		break;
	}

	case d_fmt:{		/* 1 */
		union ieee754dp(*handler) (union ieee754dp, union ieee754dp, union ieee754dp);
		union ieee754dp fd, fr, fs, ft;
		u64 __user *va;
		u64 val;

		switch (MIPSInst_FUNC(ir)) {
		case ldxc1_op:
			va = (void __user *) (xcp->regs[MIPSInst_FR(ir)] +
				xcp->regs[MIPSInst_FT(ir)]);

			MIPS_FPU_EMU_INC_STATS(loads);
			if (!access_ok(VERIFY_READ, va, sizeof(u64))) {
				MIPS_FPU_EMU_INC_STATS(errors);
				*fault_addr = va;
				return SIGBUS;
			}
			if (__get_user(val, va)) {
				MIPS_FPU_EMU_INC_STATS(errors);
				*fault_addr = va;
				return SIGSEGV;
			}
			DITOREG(val, MIPSInst_FD(ir));
			break;

		case sdxc1_op:
			va = (void __user *) (xcp->regs[MIPSInst_FR(ir)] +
				xcp->regs[MIPSInst_FT(ir)]);

			MIPS_FPU_EMU_INC_STATS(stores);
			DIFROMREG(val, MIPSInst_FS(ir));
			if (!access_ok(VERIFY_WRITE, va, sizeof(u64))) {
				MIPS_FPU_EMU_INC_STATS(errors);
				*fault_addr = va;
				return SIGBUS;
			}
			if (__put_user(val, va)) {
				MIPS_FPU_EMU_INC_STATS(errors);
				*fault_addr = va;
				return SIGSEGV;
			}
			break;

		case madd_d_op:
			handler = fpemu_dp_madd;
			goto dcoptop;
		case msub_d_op:
			handler = fpemu_dp_msub;
			goto dcoptop;
		case nmadd_d_op:
			handler = fpemu_dp_nmadd;
			goto dcoptop;
		case nmsub_d_op:
			handler = fpemu_dp_nmsub;
			goto dcoptop;

		      dcoptop:
			DPFROMREG(fr, MIPSInst_FR(ir));
			DPFROMREG(fs, MIPSInst_FS(ir));
			DPFROMREG(ft, MIPSInst_FT(ir));
			fd = (*handler) (fr, fs, ft);
			DPTOREG(fd, MIPSInst_FD(ir));
			goto copcsr;

		default:
			return SIGILL;
		}
		break;
	}

	case 0x3:
		if (MIPSInst_FUNC(ir) != pfetch_op)
			return SIGILL;

		/* ignore prefx operation */
		break;

	default:
		return SIGILL;
	}

	return 0;
}


/*
 * Emulate a single COP1 arithmetic instruction.
 */
static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
	mips_instruction ir)
{
	int rfmt;		/* resulting format */
	unsigned rcsr = 0;	/* resulting csr */
	unsigned int oldrm;
	unsigned int cbit;
	unsigned cond;
	union {
		union ieee754dp d;
		union ieee754sp s;
		int w;
		s64 l;
	} rv;			/* resulting value */
	u64 bits;

	MIPS_FPU_EMU_INC_STATS(cp1ops);
	switch (rfmt = (MIPSInst_FFMT(ir) & 0xf)) {
	case s_fmt: {		/* 0 */
		union {
			union ieee754sp(*b) (union ieee754sp, union ieee754sp);
			union ieee754sp(*u) (union ieee754sp);
		} handler;
		union ieee754sp fs, ft;

		switch (MIPSInst_FUNC(ir)) {
			/* binary ops */
		case fadd_op:
			handler.b = ieee754sp_add;
			goto scopbop;
		case fsub_op:
			handler.b = ieee754sp_sub;
			goto scopbop;
		case fmul_op:
			handler.b = ieee754sp_mul;
			goto scopbop;
		case fdiv_op:
			handler.b = ieee754sp_div;
			goto scopbop;

			/* unary  ops */
		case fsqrt_op:
			if (!cpu_has_mips_2_3_4_5_r)
				return SIGILL;

			handler.u = ieee754sp_sqrt;
			goto scopuop;

		/*
		 * Note that on some MIPS IV implementations such as the
		 * R5000 and R8000 the FSQRT and FRECIP instructions do not
		 * achieve full IEEE-754 accuracy - however this emulator does.
		 */
		case frsqrt_op:
			if (!cpu_has_mips_4_5_64_r2_r6)
				return SIGILL;

			handler.u = fpemu_sp_rsqrt;
			goto scopuop;

		case frecip_op:
			if (!cpu_has_mips_4_5_64_r2_r6)
				return SIGILL;

			handler.u = fpemu_sp_recip;
			goto scopuop;

		case fmovc_op:
			if (!cpu_has_mips_4_5_r)
				return SIGILL;

			cond = fpucondbit[MIPSInst_FT(ir) >> 2];
			if (((ctx->fcr31 & cond) != 0) !=
				((MIPSInst_FT(ir) & 1) != 0))
				return 0;
			SPFROMREG(rv.s, MIPSInst_FS(ir));
			break;

		case fmovz_op:
			if (!cpu_has_mips_4_5_r)
				return SIGILL;

			if (xcp->regs[MIPSInst_FT(ir)] != 0)
				return 0;
			SPFROMREG(rv.s, MIPSInst_FS(ir));
			break;

		case fmovn_op:
			if (!cpu_has_mips_4_5_r)
				return SIGILL;

			if (xcp->regs[MIPSInst_FT(ir)] == 0)
				return 0;
			SPFROMREG(rv.s, MIPSInst_FS(ir));
			break;

		case fabs_op:
			handler.u = ieee754sp_abs;
			goto scopuop;

		case fneg_op:
			handler.u = ieee754sp_neg;
			goto scopuop;

		case fmov_op:
			/* an easy one */
			SPFROMREG(rv.s, MIPSInst_FS(ir));
			goto copcsr;

			/* binary op on handler */
scopbop:
			SPFROMREG(fs, MIPSInst_FS(ir));
			SPFROMREG(ft, MIPSInst_FT(ir));

			rv.s = (*handler.b) (fs, ft);
			goto copcsr;
scopuop:
			SPFROMREG(fs, MIPSInst_FS(ir));
			rv.s = (*handler.u) (fs);
			goto copcsr;
copcsr:
			if (ieee754_cxtest(IEEE754_INEXACT)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_inexact);
				rcsr |= FPU_CSR_INE_X | FPU_CSR_INE_S;
			}
			if (ieee754_cxtest(IEEE754_UNDERFLOW)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_underflow);
				rcsr |= FPU_CSR_UDF_X | FPU_CSR_UDF_S;
			}
			if (ieee754_cxtest(IEEE754_OVERFLOW)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_overflow);
				rcsr |= FPU_CSR_OVF_X | FPU_CSR_OVF_S;
			}
			if (ieee754_cxtest(IEEE754_ZERO_DIVIDE)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_zerodiv);
				rcsr |= FPU_CSR_DIV_X | FPU_CSR_DIV_S;
			}
			if (ieee754_cxtest(IEEE754_INVALID_OPERATION)) {
				MIPS_FPU_EMU_INC_STATS(ieee754_invalidop);
				rcsr |= FPU_CSR_INV_X | FPU_CSR_INV_S;
			}
			break;

			/* unary conv ops */
		case fcvts_op:
			return SIGILL;	/* not defined */

		case fcvtd_op:
			SPFROMREG(fs, MIPSInst_FS(ir));
			rv.d = ieee754dp_fsp(fs);
			rfmt = d_fmt;
			goto copcsr;

		case fcvtw_op:
			SPFROMREG(fs, MIPSInst_FS(ir));
			rv.w = ieee754sp_tint(fs);
			rfmt = w_fmt;
			goto copcsr;

		case fround_op:
		case ftrunc_op:
		case fceil_op:
		case ffloor_op:
			if (!cpu_has_mips_2_3_4_5_r)
				return SIGILL;

			oldrm = ieee754_csr.rm;
			SPFROMREG(fs, MIPSInst_FS(ir));
			ieee754_csr.rm = MIPSInst_FUNC(ir);
			rv.w = ieee754sp_tint(fs);
			ieee754_csr.rm = oldrm;
			rfmt = w_fmt;
			goto copcsr;

		case fcvtl_op:
			if (!cpu_has_mips_3_4_5_64_r2_r6)
				return SIGILL;

			SPFROMREG(fs, MIPSInst_FS(ir));
			rv.l = ieee754sp_tlong(fs);
			rfmt = l_fmt;
			goto copcsr;

		case froundl_op:
		case ftruncl_op:
		case fceill_op:
		case ffloorl_op:
			if (!cpu_has_mips_3_4_5_64_r2_r6)
				return SIGILL;

			oldrm = ieee754_csr.rm;
			SPFROMREG(fs, MIPSInst_FS(ir));
			ieee754_csr.rm = MIPSInst_FUNC(ir);
			rv.l = ieee754sp_tlong(fs);
			ieee754_csr.rm = oldrm;
			rfmt = l_fmt;
			goto copcsr;

		default:
			if (MIPSInst_FUNC(ir) >= fcmp_op) {
				unsigned cmpop = MIPSInst_FUNC(ir) - fcmp_op;
				union ieee754sp fs, ft;

				SPFROMREG(fs, MIPSInst_FS(ir));
				SPFROMREG(ft, MIPSInst_FT(ir));
				rv.w = ieee754sp_cmp(fs, ft,
					cmptab[cmpop & 0x7], cmpop & 0x8);
				rfmt = -1;
				if ((cmpop & 0x8) && ieee754_cxtest
					(IEEE754_INVALID_OPERATION))
					rcsr = FPU_CSR_INV_X | FPU_CSR_INV_S;
				else
					goto copcsr;

			} else
				return SIGILL;
			break;
		}
		break;
	}

	case d_fmt: {
		union ieee754dp fs, ft;
		union {
			union ieee754dp(*b) (union ieee754dp, union ieee754dp);
			union ieee754dp(*u) (union ieee754dp);
		} handler;

		switch (MIPSInst_FUNC(ir)) {
			/* binary ops */
		case fadd_op:
			handler.b = ieee754dp_add;
			goto dcopbop;
		case fsub_op:
			handler.b = ieee754dp_sub;
			goto dcopbop;
		case fmul_op:
			handler.b = ieee754dp_mul;
			goto dcopbop;
		case fdiv_op:
			handler.b = ieee754dp_div;
			goto dcopbop;

			/* unary  ops */
		case fsqrt_op:
			if (!cpu_has_mips_2_3_4_5_r)
				return SIGILL;

			handler.u = ieee754dp_sqrt;
			goto dcopuop;
		/*
		 * Note that on some MIPS IV implementations such as the
		 * R5000 and R8000 the FSQRT and FRECIP instructions do not
		 * achieve full IEEE-754 accuracy - however this emulator does.
		 */
		case frsqrt_op:
			if (!cpu_has_mips_4_5_64_r2_r6)
				return SIGILL;

			handler.u = fpemu_dp_rsqrt;
			goto dcopuop;
		case frecip_op:
			if (!cpu_has_mips_4_5_64_r2_r6)
				return SIGILL;

			handler.u = fpemu_dp_recip;
			goto dcopuop;
		case fmovc_op:
			if (!cpu_has_mips_4_5_r)
				return SIGILL;

			cond = fpucondbit[MIPSInst_FT(ir) >> 2];
			if (((ctx->fcr31 & cond) != 0) !=
				((MIPSInst_FT(ir) & 1) != 0))
				return 0;
			DPFROMREG(rv.d, MIPSInst_FS(ir));
			break;
		case fmovz_op:
			if (!cpu_has_mips_4_5_r)
				return SIGILL;

			if (xcp->regs[MIPSInst_FT(ir)] != 0)
				return 0;
			DPFROMREG(rv.d, MIPSInst_FS(ir));
			break;
		case fmovn_op:
			if (!cpu_has_mips_4_5_r)
				return SIGILL;

			if (xcp->regs[MIPSInst_FT(ir)] == 0)
				return 0;
			DPFROMREG(rv.d, MIPSInst_FS(ir));
			break;
		case fabs_op:
			handler.u = ieee754dp_abs;
			goto dcopuop;

		case fneg_op:
			handler.u = ieee754dp_neg;
			goto dcopuop;

		case fmov_op:
			/* an easy one */
			DPFROMREG(rv.d, MIPSInst_FS(ir));
			goto copcsr;

			/* binary op on handler */
dcopbop:
			DPFROMREG(fs, MIPSInst_FS(ir));
			DPFROMREG(ft, MIPSInst_FT(ir));

			rv.d = (*handler.b) (fs, ft);
			goto copcsr;
dcopuop:
			DPFROMREG(fs, MIPSInst_FS(ir));
			rv.d = (*handler.u) (fs);
			goto copcsr;

		/*
		 * unary conv ops
		 */
		case fcvts_op:
			DPFROMREG(fs, MIPSInst_FS(ir));
			rv.s = ieee754sp_fdp(fs);
			rfmt = s_fmt;
			goto copcsr;

		case fcvtd_op:
			return SIGILL;	/* not defined */

		case fcvtw_op:
			DPFROMREG(fs, MIPSInst_FS(ir));
			rv.w = ieee754dp_tint(fs);	/* wrong */
			rfmt = w_fmt;
			goto copcsr;

		case fround_op:
		case ftrunc_op:
		case fceil_op:
		case ffloor_op:
			if (!cpu_has_mips_2_3_4_5_r)
				return SIGILL;

			oldrm = ieee754_csr.rm;
			DPFROMREG(fs, MIPSInst_FS(ir));
			ieee754_csr.rm = MIPSInst_FUNC(ir);
			rv.w = ieee754dp_tint(fs);
			ieee754_csr.rm = oldrm;
			rfmt = w_fmt;
			goto copcsr;

		case fcvtl_op:
			if (!cpu_has_mips_3_4_5_64_r2_r6)
				return SIGILL;

			DPFROMREG(fs, MIPSInst_FS(ir));
			rv.l = ieee754dp_tlong(fs);
			rfmt = l_fmt;
			goto copcsr;

		case froundl_op:
		case ftruncl_op:
		case fceill_op:
		case ffloorl_op:
			if (!cpu_has_mips_3_4_5_64_r2_r6)
				return SIGILL;

			oldrm = ieee754_csr.rm;
			DPFROMREG(fs, MIPSInst_FS(ir));
			ieee754_csr.rm = MIPSInst_FUNC(ir);
			rv.l = ieee754dp_tlong(fs);
			ieee754_csr.rm = oldrm;
			rfmt = l_fmt;
			goto copcsr;

		default:
			if (MIPSInst_FUNC(ir) >= fcmp_op) {
				unsigned cmpop = MIPSInst_FUNC(ir) - fcmp_op;
				union ieee754dp fs, ft;

				DPFROMREG(fs, MIPSInst_FS(ir));
				DPFROMREG(ft, MIPSInst_FT(ir));
				rv.w = ieee754dp_cmp(fs, ft,
					cmptab[cmpop & 0x7], cmpop & 0x8);
				rfmt = -1;
				if ((cmpop & 0x8)
					&&
					ieee754_cxtest
					(IEEE754_INVALID_OPERATION))
					rcsr = FPU_CSR_INV_X | FPU_CSR_INV_S;
				else
					goto copcsr;

			}
			else {
				return SIGILL;
			}
			break;
		}
		break;

	case w_fmt:
		switch (MIPSInst_FUNC(ir)) {
		case fcvts_op:
			/* convert word to single precision real */
			SPFROMREG(fs, MIPSInst_FS(ir));
			rv.s = ieee754sp_fint(fs.bits);
			rfmt = s_fmt;
			goto copcsr;
		case fcvtd_op:
			/* convert word to double precision real */
			SPFROMREG(fs, MIPSInst_FS(ir));
			rv.d = ieee754dp_fint(fs.bits);
			rfmt = d_fmt;
			goto copcsr;
		default:
			return SIGILL;
		}
		break;
	}

	case l_fmt:

		if (!cpu_has_mips_3_4_5_64_r2_r6)
			return SIGILL;

		DIFROMREG(bits, MIPSInst_FS(ir));

		switch (MIPSInst_FUNC(ir)) {
		case fcvts_op:
			/* convert long to single precision real */
			rv.s = ieee754sp_flong(bits);
			rfmt = s_fmt;
			goto copcsr;
		case fcvtd_op:
			/* convert long to double precision real */
			rv.d = ieee754dp_flong(bits);
			rfmt = d_fmt;
			goto copcsr;
		default:
			return SIGILL;
		}
		break;

	default:
		return SIGILL;
	}

	/*
	 * Update the fpu CSR register for this operation.
	 * If an exception is required, generate a tidy SIGFPE exception,
	 * without updating the result register.
	 * Note: cause exception bits do not accumulate, they are rewritten
	 * for each op; only the flag/sticky bits accumulate.
	 */
	ctx->fcr31 = (ctx->fcr31 & ~FPU_CSR_ALL_X) | rcsr;
	if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
		/*printk ("SIGFPE: FPU csr = %08x\n",ctx->fcr31); */
		return SIGFPE;
	}

	/*
	 * Now we can safely write the result back to the register file.
	 */
	switch (rfmt) {
	case -1:

		if (cpu_has_mips_4_5_r)
			cbit = fpucondbit[MIPSInst_FD(ir) >> 2];
		else
			cbit = FPU_CSR_COND;
		if (rv.w)
			ctx->fcr31 |= cbit;
		else
			ctx->fcr31 &= ~cbit;
		break;

	case d_fmt:
		DPTOREG(rv.d, MIPSInst_FD(ir));
		break;
	case s_fmt:
		SPTOREG(rv.s, MIPSInst_FD(ir));
		break;
	case w_fmt:
		SITOREG(rv.w, MIPSInst_FD(ir));
		break;
	case l_fmt:
		if (!cpu_has_mips_3_4_5_64_r2_r6)
			return SIGILL;

		DITOREG(rv.l, MIPSInst_FD(ir));
		break;
	default:
		return SIGILL;
	}

	return 0;
}

int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
	int has_fpu, void *__user *fault_addr)
{
	unsigned long oldepc, prevepc;
	struct mm_decoded_insn dec_insn;
	u16 instr[4];
	u16 *instr_ptr;
	int sig = 0;

	oldepc = xcp->cp0_epc;
	do {
		prevepc = xcp->cp0_epc;

		if (get_isa16_mode(prevepc) && cpu_has_mmips) {
			/*
			 * Get next 2 microMIPS instructions and convert them
			 * into 32-bit instructions.
			 */
			if ((get_user(instr[0], (u16 __user *)msk_isa16_mode(xcp->cp0_epc))) ||
			    (get_user(instr[1], (u16 __user *)msk_isa16_mode(xcp->cp0_epc + 2))) ||
			    (get_user(instr[2], (u16 __user *)msk_isa16_mode(xcp->cp0_epc + 4))) ||
			    (get_user(instr[3], (u16 __user *)msk_isa16_mode(xcp->cp0_epc + 6)))) {
				MIPS_FPU_EMU_INC_STATS(errors);
				return SIGBUS;
			}
			instr_ptr = instr;

			/* Get first instruction. */
			if (mm_insn_16bit(*instr_ptr)) {
				/* Duplicate the half-word. */
				dec_insn.insn = (*instr_ptr << 16) |
					(*instr_ptr);
				/* 16-bit instruction. */
				dec_insn.pc_inc = 2;
				instr_ptr += 1;
			} else {
				dec_insn.insn = (*instr_ptr << 16) |
					*(instr_ptr+1);
				/* 32-bit instruction. */
				dec_insn.pc_inc = 4;
				instr_ptr += 2;
			}
			/* Get second instruction. */
			if (mm_insn_16bit(*instr_ptr)) {
				/* Duplicate the half-word. */
				dec_insn.next_insn = (*instr_ptr << 16) |
					(*instr_ptr);
				/* 16-bit instruction. */
				dec_insn.next_pc_inc = 2;
			} else {
				dec_insn.next_insn = (*instr_ptr << 16) |
					*(instr_ptr+1);
				/* 32-bit instruction. */
				dec_insn.next_pc_inc = 4;
			}
			dec_insn.micro_mips_mode = 1;
		} else {
			if ((get_user(dec_insn.insn,
			    (mips_instruction __user *) xcp->cp0_epc)) ||
			    (get_user(dec_insn.next_insn,
			    (mips_instruction __user *)(xcp->cp0_epc+4)))) {
				MIPS_FPU_EMU_INC_STATS(errors);
				return SIGBUS;
			}
			dec_insn.pc_inc = 4;
			dec_insn.next_pc_inc = 4;
			dec_insn.micro_mips_mode = 0;
		}

		if ((dec_insn.insn == 0) ||
		   ((dec_insn.pc_inc == 2) &&
		   ((dec_insn.insn & 0xffff) == MM_NOP16)))
			xcp->cp0_epc += dec_insn.pc_inc;	/* Skip NOPs */
		else {
			/*
			 * The 'ieee754_csr' is an alias of ctx->fcr31.
			 * No need to copy ctx->fcr31 to ieee754_csr.
			 */
			sig = cop1Emulate(xcp, ctx, dec_insn, fault_addr);
		}

		if (has_fpu)
			break;
		if (sig)
			break;

		cond_resched();
	} while (xcp->cp0_epc > prevepc);

	/* SIGILL indicates a non-fpu instruction */
	if (sig == SIGILL && xcp->cp0_epc != oldepc)
		/* but if EPC has advanced, then ignore it */
		sig = 0;

	return sig;
}