Initial import

1 files changed, 880 insertions, 0 deletions

diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
new file mode 100644
index 000000000..c0c5e5972
--- /dev/null
+++ b/arch/mips/kernel/branch.c
@@ -0,0 +1,880 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1996, 97, 2000, 2001 by Ralf Baechle
+ * Copyright (C) 2001 MIPS Technologies, Inc.
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/module.h>
+#include <asm/branch.h>
+#include <asm/cpu.h>
+#include <asm/cpu-features.h>
+#include <asm/fpu.h>
+#include <asm/fpu_emulator.h>
+#include <asm/inst.h>
+#include <asm/mips-r2-to-r6-emul.h>
+#include <asm/ptrace.h>
+#include <asm/uaccess.h>
+
+/*
+ * Calculate and return exception PC in case of branch delay slot
+ * for microMIPS and MIPS16e. It does not clear the ISA mode bit.
+ */
+int __isa_exception_epc(struct pt_regs *regs)
+{
+	unsigned short inst;
+	long epc = regs->cp0_epc;
+
+	/* Calculate exception PC in branch delay slot. */
+	if (__get_user(inst, (u16 __user *) msk_isa16_mode(epc))) {
+		/* This should never happen because delay slot was checked. */
+		force_sig(SIGSEGV, current);
+		return epc;
+	}
+	if (cpu_has_mips16) {
+		union mips16e_instruction inst_mips16e;
+
+		inst_mips16e.full = inst;
+		if (inst_mips16e.ri.opcode == MIPS16e_jal_op)
+			epc += 4;
+		else
+			epc += 2;
+	} else if (mm_insn_16bit(inst))
+		epc += 2;
+	else
+		epc += 4;
+
+	return epc;
+}
+
+/* (microMIPS) Convert 16-bit register encoding to 32-bit register encoding. */
+static const unsigned int reg16to32map[8] = {16, 17, 2, 3, 4, 5, 6, 7};
+
+int __mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
+		       unsigned long *contpc)
+{
+	union mips_instruction insn = (union mips_instruction)dec_insn.insn;
+	int bc_false = 0;
+	unsigned int fcr31;
+	unsigned int bit;
+
+	if (!cpu_has_mmips)
+		return 0;
+
+	switch (insn.mm_i_format.opcode) {
+	case mm_pool32a_op:
+		if ((insn.mm_i_format.simmediate & MM_POOL32A_MINOR_MASK) ==
+		    mm_pool32axf_op) {
+			switch (insn.mm_i_format.simmediate >>
+				MM_POOL32A_MINOR_SHIFT) {
+			case mm_jalr_op:
+			case mm_jalrhb_op:
+			case mm_jalrs_op:
+			case mm_jalrshb_op:
+				if (insn.mm_i_format.rt != 0)	/* Not mm_jr */
+					regs->regs[insn.mm_i_format.rt] =
+						regs->cp0_epc +
+						dec_insn.pc_inc +
+						dec_insn.next_pc_inc;
+				*contpc = regs->regs[insn.mm_i_format.rs];
+				return 1;
+			}
+		}
+		break;
+	case mm_pool32i_op:
+		switch (insn.mm_i_format.rt) {
+		case mm_bltzals_op:
+		case mm_bltzal_op:
+			regs->regs[31] = regs->cp0_epc +
+				dec_insn.pc_inc +
+				dec_insn.next_pc_inc;
+			/* Fall through */
+		case mm_bltz_op:
+			if ((long)regs->regs[insn.mm_i_format.rs] < 0)
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					(insn.mm_i_format.simmediate << 1);
+			else
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					dec_insn.next_pc_inc;
+			return 1;
+		case mm_bgezals_op:
+		case mm_bgezal_op:
+			regs->regs[31] = regs->cp0_epc +
+					dec_insn.pc_inc +
+					dec_insn.next_pc_inc;
+			/* Fall through */
+		case mm_bgez_op:
+			if ((long)regs->regs[insn.mm_i_format.rs] >= 0)
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					(insn.mm_i_format.simmediate << 1);
+			else
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					dec_insn.next_pc_inc;
+			return 1;
+		case mm_blez_op:
+			if ((long)regs->regs[insn.mm_i_format.rs] <= 0)
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					(insn.mm_i_format.simmediate << 1);
+			else
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					dec_insn.next_pc_inc;
+			return 1;
+		case mm_bgtz_op:
+			if ((long)regs->regs[insn.mm_i_format.rs] <= 0)
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					(insn.mm_i_format.simmediate << 1);
+			else
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					dec_insn.next_pc_inc;
+			return 1;
+		case mm_bc2f_op:
+		case mm_bc1f_op:
+			bc_false = 1;
+			/* Fall through */
+		case mm_bc2t_op:
+		case mm_bc1t_op:
+			preempt_disable();
+			if (is_fpu_owner())
+			        fcr31 = read_32bit_cp1_register(CP1_STATUS);
+			else
+				fcr31 = current->thread.fpu.fcr31;
+			preempt_enable();
+
+			if (bc_false)
+				fcr31 = ~fcr31;
+
+			bit = (insn.mm_i_format.rs >> 2);
+			bit += (bit != 0);
+			bit += 23;
+			if (fcr31 & (1 << bit))
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc +
+					(insn.mm_i_format.simmediate << 1);
+			else
+				*contpc = regs->cp0_epc +
+					dec_insn.pc_inc + dec_insn.next_pc_inc;
+			return 1;
+		}
+		break;
+	case mm_pool16c_op:
+		switch (insn.mm_i_format.rt) {
+		case mm_jalr16_op:
+		case mm_jalrs16_op:
+			regs->regs[31] = regs->cp0_epc +
+				dec_insn.pc_inc + dec_insn.next_pc_inc;
+			/* Fall through */
+		case mm_jr16_op:
+			*contpc = regs->regs[insn.mm_i_format.rs];
+			return 1;
+		}
+		break;
+	case mm_beqz16_op:
+		if ((long)regs->regs[reg16to32map[insn.mm_b1_format.rs]] == 0)
+			*contpc = regs->cp0_epc +
+				dec_insn.pc_inc +
+				(insn.mm_b1_format.simmediate << 1);
+		else
+			*contpc = regs->cp0_epc +
+				dec_insn.pc_inc + dec_insn.next_pc_inc;
+		return 1;
+	case mm_bnez16_op:
+		if ((long)regs->regs[reg16to32map[insn.mm_b1_format.rs]] != 0)
+			*contpc = regs->cp0_epc +
+				dec_insn.pc_inc +
+				(insn.mm_b1_format.simmediate << 1);
+		else
+			*contpc = regs->cp0_epc +
+				dec_insn.pc_inc + dec_insn.next_pc_inc;
+		return 1;
+	case mm_b16_op:
+		*contpc = regs->cp0_epc + dec_insn.pc_inc +
+			 (insn.mm_b0_format.simmediate << 1);
+		return 1;
+	case mm_beq32_op:
+		if (regs->regs[insn.mm_i_format.rs] ==
+		    regs->regs[insn.mm_i_format.rt])
+			*contpc = regs->cp0_epc +
+				dec_insn.pc_inc +
+				(insn.mm_i_format.simmediate << 1);
+		else
+			*contpc = regs->cp0_epc +
+				dec_insn.pc_inc +
+				dec_insn.next_pc_inc;
+		return 1;
+	case mm_bne32_op:
+		if (regs->regs[insn.mm_i_format.rs] !=
+		    regs->regs[insn.mm_i_format.rt])
+			*contpc = regs->cp0_epc +
+				dec_insn.pc_inc +
+				(insn.mm_i_format.simmediate << 1);
+		else
+			*contpc = regs->cp0_epc +
+				dec_insn.pc_inc + dec_insn.next_pc_inc;
+		return 1;
+	case mm_jalx32_op:
+		regs->regs[31] = regs->cp0_epc +
+			dec_insn.pc_inc + dec_insn.next_pc_inc;
+		*contpc = regs->cp0_epc + dec_insn.pc_inc;
+		*contpc >>= 28;
+		*contpc <<= 28;
+		*contpc |= (insn.j_format.target << 2);
+		return 1;
+	case mm_jals32_op:
+	case mm_jal32_op:
+		regs->regs[31] = regs->cp0_epc +
+			dec_insn.pc_inc + dec_insn.next_pc_inc;
+		/* Fall through */
+	case mm_j32_op:
+		*contpc = regs->cp0_epc + dec_insn.pc_inc;
+		*contpc >>= 27;
+		*contpc <<= 27;
+		*contpc |= (insn.j_format.target << 1);
+		set_isa16_mode(*contpc);
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Compute return address and emulate branch in microMIPS mode after an
+ * exception only. It does not handle compact branches/jumps and cannot
+ * be used in interrupt context. (Compact branches/jumps do not cause
+ * exceptions.)
+ */
+int __microMIPS_compute_return_epc(struct pt_regs *regs)
+{
+	u16 __user *pc16;
+	u16 halfword;
+	unsigned int word;
+	unsigned long contpc;
+	struct mm_decoded_insn mminsn = { 0 };
+
+	mminsn.micro_mips_mode = 1;
+
+	/* This load never faults. */
+	pc16 = (unsigned short __user *)msk_isa16_mode(regs->cp0_epc);
+	__get_user(halfword, pc16);
+	pc16++;
+	contpc = regs->cp0_epc + 2;
+	word = ((unsigned int)halfword << 16);
+	mminsn.pc_inc = 2;
+
+	if (!mm_insn_16bit(halfword)) {
+		__get_user(halfword, pc16);
+		pc16++;
+		contpc = regs->cp0_epc + 4;
+		mminsn.pc_inc = 4;
+		word |= halfword;
+	}
+	mminsn.insn = word;
+
+	if (get_user(halfword, pc16))
+		goto sigsegv;
+	mminsn.next_pc_inc = 2;
+	word = ((unsigned int)halfword << 16);
+
+	if (!mm_insn_16bit(halfword)) {
+		pc16++;
+		if (get_user(halfword, pc16))
+			goto sigsegv;
+		mminsn.next_pc_inc = 4;
+		word |= halfword;
+	}
+	mminsn.next_insn = word;
+
+	mm_isBranchInstr(regs, mminsn, &contpc);
+
+	regs->cp0_epc = contpc;
+
+	return 0;
+
+sigsegv:
+	force_sig(SIGSEGV, current);
+	return -EFAULT;
+}
+
+/*
+ * Compute return address and emulate branch in MIPS16e mode after an
+ * exception only. It does not handle compact branches/jumps and cannot
+ * be used in interrupt context. (Compact branches/jumps do not cause
+ * exceptions.)
+ */
+int __MIPS16e_compute_return_epc(struct pt_regs *regs)
+{
+	u16 __user *addr;
+	union mips16e_instruction inst;
+	u16 inst2;
+	u32 fullinst;
+	long epc;
+
+	epc = regs->cp0_epc;
+
+	/* Read the instruction. */
+	addr = (u16 __user *)msk_isa16_mode(epc);
+	if (__get_user(inst.full, addr)) {
+		force_sig(SIGSEGV, current);
+		return -EFAULT;
+	}
+
+	switch (inst.ri.opcode) {
+	case MIPS16e_extend_op:
+		regs->cp0_epc += 4;
+		return 0;
+
+		/*
+		 *  JAL and JALX in MIPS16e mode
+		 */
+	case MIPS16e_jal_op:
+		addr += 1;
+		if (__get_user(inst2, addr)) {
+			force_sig(SIGSEGV, current);
+			return -EFAULT;
+		}
+		fullinst = ((unsigned)inst.full << 16) | inst2;
+		regs->regs[31] = epc + 6;
+		epc += 4;
+		epc >>= 28;
+		epc <<= 28;
+		/*
+		 * JAL:5 X:1 TARGET[20-16]:5 TARGET[25:21]:5 TARGET[15:0]:16
+		 *
+		 * ......TARGET[15:0].................TARGET[20:16]...........
+		 * ......TARGET[25:21]
+		 */
+		epc |=
+		    ((fullinst & 0xffff) << 2) | ((fullinst & 0x3e00000) >> 3) |
+		    ((fullinst & 0x1f0000) << 7);
+		if (!inst.jal.x)
+			set_isa16_mode(epc);	/* Set ISA mode bit. */
+		regs->cp0_epc = epc;
+		return 0;
+
+		/*
+		 *  J(AL)R(C)
+		 */
+	case MIPS16e_rr_op:
+		if (inst.rr.func == MIPS16e_jr_func) {
+
+			if (inst.rr.ra)
+				regs->cp0_epc = regs->regs[31];
+			else
+				regs->cp0_epc =
+				    regs->regs[reg16to32[inst.rr.rx]];
+
+			if (inst.rr.l) {
+				if (inst.rr.nd)
+					regs->regs[31] = epc + 2;
+				else
+					regs->regs[31] = epc + 4;
+			}
+			return 0;
+		}
+		break;
+	}
+
+	/*
+	 * All other cases have no branch delay slot and are 16-bits.
+	 * Branches do not cause an exception.
+	 */
+	regs->cp0_epc += 2;
+
+	return 0;
+}
+
+/**
+ * __compute_return_epc_for_insn - Computes the return address and do emulate
+ *				    branch simulation, if required.
+ *
+ * @regs:	Pointer to pt_regs
+ * @insn:	branch instruction to decode
+ * @returns:	-EFAULT on error and forces SIGBUS, and on success
+ *		returns 0 or BRANCH_LIKELY_TAKEN as appropriate after
+ *		evaluating the branch.
+ *
+ * MIPS R6 Compact branches and forbidden slots:
+ *	Compact branches do not throw exceptions because they do
+ *	not have delay slots. The forbidden slot instruction ($PC+4)
+ *	is only executed if the branch was not taken. Otherwise the
+ *	forbidden slot is skipped entirely. This means that the
+ *	only possible reason to be here because of a MIPS R6 compact
+ *	branch instruction is that the forbidden slot has thrown one.
+ *	In that case the branch was not taken, so the EPC can be safely
+ *	set to EPC + 8.
+ */
+int __compute_return_epc_for_insn(struct pt_regs *regs,
+				   union mips_instruction insn)
+{
+	unsigned int bit, fcr31, dspcontrol, reg;
+	long epc = regs->cp0_epc;
+	int ret = 0;
+
+	switch (insn.i_format.opcode) {
+	/*
+	 * jr and jalr are in r_format format.
+	 */
+	case spec_op:
+		switch (insn.r_format.func) {
+		case jalr_op:
+			regs->regs[insn.r_format.rd] = epc + 8;
+			/* Fall through */
+		case jr_op:
+			if (NO_R6EMU && insn.r_format.func == jr_op)
+				goto sigill_r6;
+			regs->cp0_epc = regs->regs[insn.r_format.rs];
+			break;
+		}
+		break;
+
+	/*
+	 * This group contains:
+	 * bltz_op, bgez_op, bltzl_op, bgezl_op,
+	 * bltzal_op, bgezal_op, bltzall_op, bgezall_op.
+	 */
+	case bcond_op:
+		switch (insn.i_format.rt) {
+		case bltzl_op:
+			if (NO_R6EMU)
+				goto sigill_r6;
+		case bltz_op:
+			if ((long)regs->regs[insn.i_format.rs] < 0) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == bltzl_op)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case bgezl_op:
+			if (NO_R6EMU)
+				goto sigill_r6;
+		case bgez_op:
+			if ((long)regs->regs[insn.i_format.rs] >= 0) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == bgezl_op)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case bltzal_op:
+		case bltzall_op:
+			if (NO_R6EMU && (insn.i_format.rs ||
+			    insn.i_format.rt == bltzall_op)) {
+				ret = -SIGILL;
+				break;
+			}
+			regs->regs[31] = epc + 8;
+			/*
+			 * OK we are here either because we hit a NAL
+			 * instruction or because we are emulating an
+			 * old bltzal{,l} one. Lets figure out what the
+			 * case really is.
+			 */
+			if (!insn.i_format.rs) {
+				/*
+				 * NAL or BLTZAL with rs == 0
+				 * Doesn't matter if we are R6 or not. The
+				 * result is the same
+				 */
+				regs->cp0_epc += 4 +
+					(insn.i_format.simmediate << 2);
+				break;
+			}
+			/* Now do the real thing for non-R6 BLTZAL{,L} */
+			if ((long)regs->regs[insn.i_format.rs] < 0) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == bltzall_op)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case bgezal_op:
+		case bgezall_op:
+			if (NO_R6EMU && (insn.i_format.rs ||
+			    insn.i_format.rt == bgezall_op)) {
+				ret = -SIGILL;
+				break;
+			}
+			regs->regs[31] = epc + 8;
+			/*
+			 * OK we are here either because we hit a BAL
+			 * instruction or because we are emulating an
+			 * old bgezal{,l} one. Lets figure out what the
+			 * case really is.
+			 */
+			if (!insn.i_format.rs) {
+				/*
+				 * BAL or BGEZAL with rs == 0
+				 * Doesn't matter if we are R6 or not. The
+				 * result is the same
+				 */
+				regs->cp0_epc += 4 +
+					(insn.i_format.simmediate << 2);
+				break;
+			}
+			/* Now do the real thing for non-R6 BGEZAL{,L} */
+			if ((long)regs->regs[insn.i_format.rs] >= 0) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == bgezall_op)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case bposge32_op:
+			if (!cpu_has_dsp)
+				goto sigill_dsp;
+
+			dspcontrol = rddsp(0x01);
+
+			if (dspcontrol >= 32) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+		}
+		break;
+
+	/*
+	 * These are unconditional and in j_format.
+	 */
+	case jal_op:
+		regs->regs[31] = regs->cp0_epc + 8;
+	case j_op:
+		epc += 4;
+		epc >>= 28;
+		epc <<= 28;
+		epc |= (insn.j_format.target << 2);
+		regs->cp0_epc = epc;
+		if (insn.i_format.opcode == jalx_op)
+			set_isa16_mode(regs->cp0_epc);
+		break;
+
+	/*
+	 * These are conditional and in i_format.
+	 */
+	case beql_op:
+		if (NO_R6EMU)
+			goto sigill_r6;
+	case beq_op:
+		if (regs->regs[insn.i_format.rs] ==
+		    regs->regs[insn.i_format.rt]) {
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+			if (insn.i_format.opcode == beql_op)
+				ret = BRANCH_LIKELY_TAKEN;
+		} else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+
+	case bnel_op:
+		if (NO_R6EMU)
+			goto sigill_r6;
+	case bne_op:
+		if (regs->regs[insn.i_format.rs] !=
+		    regs->regs[insn.i_format.rt]) {
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+			if (insn.i_format.opcode == bnel_op)
+				ret = BRANCH_LIKELY_TAKEN;
+		} else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+
+	case blezl_op: /* not really i_format */
+		if (NO_R6EMU)
+			goto sigill_r6;
+	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] = epc + 4;
+			regs->cp0_epc += 8;
+			break;
+		}
+		/* rt field assumed to be zero */
+		if ((long)regs->regs[insn.i_format.rs] <= 0) {
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+			if (insn.i_format.opcode == blezl_op)
+				ret = BRANCH_LIKELY_TAKEN;
+		} else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+
+	case bgtzl_op:
+		if (NO_R6EMU)
+			goto sigill_r6;
+	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] = epc + 4;
+			regs->cp0_epc += 8;
+			break;
+		}
+
+		/* rt field assumed to be zero */
+		if ((long)regs->regs[insn.i_format.rs] > 0) {
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+			if (insn.i_format.opcode == bgtzl_op)
+				ret = BRANCH_LIKELY_TAKEN;
+		} else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+
+	/*
+	 * And now the FPA/cp1 branch instructions.
+	 */
+	case cop1_op:
+		if (cpu_has_mips_r6 &&
+		    ((insn.i_format.rs == bc1eqz_op) ||
+		     (insn.i_format.rs == bc1nez_op))) {
+			if (!used_math()) { /* First time FPU user */
+				ret = init_fpu();
+				if (ret && NO_R6EMU) {
+					ret = -ret;
+					break;
+				}
+				ret = 0;
+				set_used_math();
+			}
+			lose_fpu(1);    /* Save FPU state for the emulator. */
+			reg = insn.i_format.rt;
+			bit = 0;
+			switch (insn.i_format.rs) {
+			case bc1eqz_op:
+				/* Test bit 0 */
+				if (get_fpr32(&current->thread.fpu.fpr[reg], 0)
+				    & 0x1)
+					bit = 1;
+				break;
+			case bc1nez_op:
+				/* Test bit 0 */
+				if (!(get_fpr32(&current->thread.fpu.fpr[reg], 0)
+				      & 0x1))
+					bit = 1;
+				break;
+			}
+			own_fpu(1);
+			if (bit)
+				epc = epc + 4 +
+					(insn.i_format.simmediate << 2);
+			else
+				epc += 8;
+			regs->cp0_epc = epc;
+
+			break;
+		} else {
+
+			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)) {
+					epc = epc + 4 +
+						(insn.i_format.simmediate << 2);
+					if (insn.i_format.rt == 2)
+						ret = BRANCH_LIKELY_TAKEN;
+				} else
+					epc += 8;
+				regs->cp0_epc = epc;
+				break;
+
+			case 1: /* bc1t */
+			case 3: /* bc1tl */
+				if (fcr31 & (1 << bit)) {
+					epc = epc + 4 +
+						(insn.i_format.simmediate << 2);
+					if (insn.i_format.rt == 3)
+						ret = BRANCH_LIKELY_TAKEN;
+				} else
+					epc += 8;
+				regs->cp0_epc = epc;
+				break;
+			}
+			break;
+		}
+#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)
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+	case ldc2_op: /* This is bbit032 on Octeon */
+		if ((regs->regs[insn.i_format.rs] &
+		    (1ull<<(insn.i_format.rt+32))) == 0)
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+	case swc2_op: /* This is bbit1 on Octeon */
+		if (regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt))
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+	case sdc2_op: /* This is bbit132 on Octeon */
+		if (regs->regs[insn.i_format.rs] &
+		    (1ull<<(insn.i_format.rt+32)))
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+#else
+	case bc6_op:
+		/* Only valid for MIPS R6 */
+		if (!cpu_has_mips_r6) {
+			ret = -SIGILL;
+			break;
+		}
+		regs->cp0_epc += 8;
+		break;
+	case balc6_op:
+		if (!cpu_has_mips_r6) {
+			ret = -SIGILL;
+			break;
+		}
+		/* Compact branch: BALC */
+		regs->regs[31] = epc + 4;
+		epc += 4 + (insn.i_format.simmediate << 2);
+		regs->cp0_epc = epc;
+		break;
+	case beqzcjic_op:
+		if (!cpu_has_mips_r6) {
+			ret = -SIGILL;
+			break;
+		}
+		/* Compact branch: BEQZC || JIC */
+		regs->cp0_epc += 8;
+		break;
+	case bnezcjialc_op:
+		if (!cpu_has_mips_r6) {
+			ret = -SIGILL;
+			break;
+		}
+		/* Compact branch: BNEZC || JIALC */
+		if (insn.i_format.rs)
+			regs->regs[31] = epc + 4;
+		regs->cp0_epc += 8;
+		break;
+#endif
+	case cbcond0_op:
+	case cbcond1_op:
+		/* Only valid for MIPS R6 */
+		if (!cpu_has_mips_r6) {
+			ret = -SIGILL;
+			break;
+		}
+		/*
+		 * Compact branches:
+		 * bovc, beqc, beqzalc, bnvc, bnec, bnezlac
+		 */
+		if (insn.i_format.rt && !insn.i_format.rs)
+			regs->regs[31] = epc + 4;
+		regs->cp0_epc += 8;
+		break;
+	}
+
+	return ret;
+
+sigill_dsp:
+	printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
+	force_sig(SIGBUS, current);
+	return -EFAULT;
+sigill_r6:
+	pr_info("%s: R2 branch but r2-to-r6 emulator is not preset - sending SIGILL.\n",
+		current->comm);
+	force_sig(SIGILL, current);
+	return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);
+
+int __compute_return_epc(struct pt_regs *regs)
+{
+	unsigned int __user *addr;
+	long epc;
+	union mips_instruction insn;
+
+	epc = regs->cp0_epc;
+	if (epc & 3)
+		goto unaligned;
+
+	/*
+	 * Read the instruction
+	 */
+	addr = (unsigned int __user *) epc;
+	if (__get_user(insn.word, addr)) {
+		force_sig(SIGSEGV, current);
+		return -EFAULT;
+	}
+
+	return __compute_return_epc_for_insn(regs, insn);
+
+unaligned:
+	printk("%s: unaligned epc - sending SIGBUS.\n", current->comm);
+	force_sig(SIGBUS, current);
+	return -EFAULT;
+}