MIPS: kernel: mips-r2-to-r6-emul: Add R2 emulator for MIPS R6

MIPS R6 removed quite a few R2 instructions. However, there
is plenty of <R6 userland code so we add an in-kernel emulator
so we can still be able to execute all R2 userland out there.

The emulator comes with a handy debugfs under /mips/ directory
(r2-emul-stats) to provide some basic statistics of the
instructions that are being emulated.

Below are some statistics from booting a minimal buildroot image:

Instruction     Total   BDslot
------------------------------
movs            236969  0
hilo            56686   0
muls            55279   0
divs            10941   0
dsps            0       0
bops            1       0
traps           0       0
fpus            0       0
loads           214981  17
stores          103364  0
llsc            56898   0
dsemul          150418  0
jr              370158
bltzl           43
bgezl           1594
bltzll          0
bgezll          0
bltzal          39
bgezal          39
beql            14503
bnel            138741
blezl           0
bgtzl           3988

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

1 files changed, 2378 insertions, 0 deletions

diff --git a/arch/mips/kernel/mips-r2-to-r6-emul.c b/arch/mips/kernel/mips-r2-to-r6-emul.c
new file mode 100644
index 000000000000..64d17e41093b
--- /dev/null
+++ b/arch/mips/kernel/mips-r2-to-r6-emul.c
@@ -0,0 +1,2378 @@
+/*
+ * 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) 2014 Imagination Technologies Ltd.
+ * Author: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
+ * Author: Markos Chandras <markos.chandras@imgtec.com>
+ *
+ *      MIPS R2 user space instruction emulator for MIPS R6
+ *
+ */
+#include <linux/bug.h>
+#include <linux/compiler.h>
+#include <linux/debugfs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/ptrace.h>
+#include <linux/seq_file.h>
+
+#include <asm/asm.h>
+#include <asm/branch.h>
+#include <asm/break.h>
+#include <asm/fpu.h>
+#include <asm/fpu_emulator.h>
+#include <asm/inst.h>
+#include <asm/mips-r2-to-r6-emul.h>
+#include <asm/local.h>
+#include <asm/ptrace.h>
+#include <asm/uaccess.h>
+
+#ifdef CONFIG_64BIT
+#define ADDIU	"daddiu "
+#define INS	"dins "
+#define EXT	"dext "
+#else
+#define ADDIU	"addiu "
+#define INS	"ins "
+#define EXT	"ext "
+#endif /* CONFIG_64BIT */
+
+#define SB	"sb "
+#define LB	"lb "
+#define LL	"ll "
+#define SC	"sc "
+
+DEFINE_PER_CPU(struct mips_r2_emulator_stats, mipsr2emustats);
+DEFINE_PER_CPU(struct mips_r2_emulator_stats, mipsr2bdemustats);
+DEFINE_PER_CPU(struct mips_r2br_emulator_stats, mipsr2bremustats);
+
+extern const unsigned int fpucondbit[8];
+
+#define MIPS_R2_EMUL_TOTAL_PASS	10
+
+int mipsr2_emulation = 0;
+
+static int __init mipsr2emu_enable(char *s)
+{
+	mipsr2_emulation = 1;
+
+	pr_info("MIPS R2-to-R6 Emulator Enabled!");
+
+	return 1;
+}
+__setup("mipsr2emu", mipsr2emu_enable);
+
+/**
+ * mipsr6_emul - Emulate some frequent R2/R5/R6 instructions in delay slot
+ * for performance instead of the traditional way of using a stack trampoline
+ * which is rather slow.
+ * @regs: Process register set
+ * @ir: Instruction
+ */
+static inline int mipsr6_emul(struct pt_regs *regs, u32 ir)
+{
+	switch (MIPSInst_OPCODE(ir)) {
+	case addiu_op:
+		if (MIPSInst_RT(ir))
+			regs->regs[MIPSInst_RT(ir)] =
+				(s32)regs->regs[MIPSInst_RS(ir)] +
+				(s32)MIPSInst_SIMM(ir);
+		return 0;
+	case daddiu_op:
+		if (config_enabled(CONFIG_32BIT))
+			break;
+
+		if (MIPSInst_RT(ir))
+			regs->regs[MIPSInst_RT(ir)] =
+				(s64)regs->regs[MIPSInst_RS(ir)] +
+				(s64)MIPSInst_SIMM(ir);
+		return 0;
+	case lwc1_op:
+	case swc1_op:
+	case cop1_op:
+	case cop1x_op:
+		/* FPU instructions in delay slot */
+		return -SIGFPE;
+	case spec_op:
+		switch (MIPSInst_FUNC(ir)) {
+		case or_op:
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					regs->regs[MIPSInst_RS(ir)] |
+					regs->regs[MIPSInst_RT(ir)];
+			return 0;
+		case sll_op:
+			if (MIPSInst_RS(ir))
+				break;
+
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					(s32)(((u32)regs->regs[MIPSInst_RT(ir)]) <<
+						MIPSInst_FD(ir));
+			return 0;
+		case srl_op:
+			if (MIPSInst_RS(ir))
+				break;
+
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					(s32)(((u32)regs->regs[MIPSInst_RT(ir)]) >>
+						MIPSInst_FD(ir));
+			return 0;
+		case addu_op:
+			if (MIPSInst_FD(ir))
+				break;
+
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					(s32)((u32)regs->regs[MIPSInst_RS(ir)] +
+					      (u32)regs->regs[MIPSInst_RT(ir)]);
+			return 0;
+		case subu_op:
+			if (MIPSInst_FD(ir))
+				break;
+
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					(s32)((u32)regs->regs[MIPSInst_RS(ir)] -
+					      (u32)regs->regs[MIPSInst_RT(ir)]);
+			return 0;
+		case dsll_op:
+			if (config_enabled(CONFIG_32BIT) || MIPSInst_RS(ir))
+				break;
+
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					(s64)(((u64)regs->regs[MIPSInst_RT(ir)]) <<
+						MIPSInst_FD(ir));
+			return 0;
+		case dsrl_op:
+			if (config_enabled(CONFIG_32BIT) || MIPSInst_RS(ir))
+				break;
+
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					(s64)(((u64)regs->regs[MIPSInst_RT(ir)]) >>
+						MIPSInst_FD(ir));
+			return 0;
+		case daddu_op:
+			if (config_enabled(CONFIG_32BIT) || MIPSInst_FD(ir))
+				break;
+
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					(u64)regs->regs[MIPSInst_RS(ir)] +
+					(u64)regs->regs[MIPSInst_RT(ir)];
+			return 0;
+		case dsubu_op:
+			if (config_enabled(CONFIG_32BIT) || MIPSInst_FD(ir))
+				break;
+
+			if (MIPSInst_RD(ir))
+				regs->regs[MIPSInst_RD(ir)] =
+					(s64)((u64)regs->regs[MIPSInst_RS(ir)] -
+					      (u64)regs->regs[MIPSInst_RT(ir)]);
+			return 0;
+		}
+		break;
+	default:
+		pr_debug("No fastpath BD emulation for instruction 0x%08x (op: %02x)\n",
+			 ir, MIPSInst_OPCODE(ir));
+	}
+
+	return SIGILL;
+}
+
+/**
+ * movt_func - Emulate a MOVT instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int movf_func(struct pt_regs *regs, u32 ir)
+{
+	u32 csr;
+	u32 cond;
+
+	csr = current->thread.fpu.fcr31;
+	cond = fpucondbit[MIPSInst_RT(ir) >> 2];
+	if (((csr & cond) == 0) && MIPSInst_RD(ir))
+		regs->regs[MIPSInst_RD(ir)] = regs->regs[MIPSInst_RS(ir)];
+	MIPS_R2_STATS(movs);
+	return 0;
+}
+
+/**
+ * movt_func - Emulate a MOVT instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int movt_func(struct pt_regs *regs, u32 ir)
+{
+	u32 csr;
+	u32 cond;
+
+	csr = current->thread.fpu.fcr31;
+	cond = fpucondbit[MIPSInst_RT(ir) >> 2];
+
+	if (((csr & cond) != 0) && MIPSInst_RD(ir))
+		regs->regs[MIPSInst_RD(ir)] = regs->regs[MIPSInst_RS(ir)];
+
+	MIPS_R2_STATS(movs);
+
+	return 0;
+}
+
+/**
+ * jr_func - Emulate a JR instruction.
+ * @pt_regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns SIGILL if JR was in delay slot, SIGEMT if we
+ * can't compute the EPC, SIGSEGV if we can't access the
+ * userland instruction or 0 on success.
+ */
+static int jr_func(struct pt_regs *regs, u32 ir)
+{
+	int err;
+	unsigned long cepc, epc, nepc;
+	u32 nir;
+
+	if (delay_slot(regs))
+		return SIGILL;
+
+	/* EPC after the RI/JR instruction */
+	nepc = regs->cp0_epc;
+	/* Roll back to the reserved R2 JR instruction */
+	regs->cp0_epc -= 4;
+	epc = regs->cp0_epc;
+	err = __compute_return_epc(regs);
+
+	if (err < 0)
+		return SIGEMT;
+
+
+	/* Computed EPC */
+	cepc = regs->cp0_epc;
+
+	/* Get DS instruction */
+	err = __get_user(nir, (u32 __user *)nepc);
+	if (err)
+		return SIGSEGV;
+
+	MIPS_R2BR_STATS(jrs);
+
+	/* If nir == 0(NOP), then nothing else to do */
+	if (nir) {
+		/*
+		 * Negative err means FPU instruction in BD-slot,
+		 * Zero err means 'BD-slot emulation done'
+		 * For anything else we go back to trampoline emulation.
+		 */
+		err = mipsr6_emul(regs, nir);
+		if (err > 0) {
+			regs->cp0_epc = nepc;
+			err = mips_dsemul(regs, nir, cepc);
+			if (err == SIGILL)
+				err = SIGEMT;
+			MIPS_R2_STATS(dsemul);
+		}
+	}
+
+	return err;
+}
+
+/**
+ * movz_func - Emulate a MOVZ instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int movz_func(struct pt_regs *regs, u32 ir)
+{
+	if (((regs->regs[MIPSInst_RT(ir)]) == 0) && MIPSInst_RD(ir))
+		regs->regs[MIPSInst_RD(ir)] = regs->regs[MIPSInst_RS(ir)];
+	MIPS_R2_STATS(movs);
+
+	return 0;
+}
+
+/**
+ * movn_func - Emulate a MOVZ instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int movn_func(struct pt_regs *regs, u32 ir)
+{
+	if (((regs->regs[MIPSInst_RT(ir)]) != 0) && MIPSInst_RD(ir))
+		regs->regs[MIPSInst_RD(ir)] = regs->regs[MIPSInst_RS(ir)];
+	MIPS_R2_STATS(movs);
+
+	return 0;
+}
+
+/**
+ * mfhi_func - Emulate a MFHI instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int mfhi_func(struct pt_regs *regs, u32 ir)
+{
+	if (MIPSInst_RD(ir))
+		regs->regs[MIPSInst_RD(ir)] = regs->hi;
+
+	MIPS_R2_STATS(hilo);
+
+	return 0;
+}
+
+/**
+ * mthi_func - Emulate a MTHI instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int mthi_func(struct pt_regs *regs, u32 ir)
+{
+	regs->hi = regs->regs[MIPSInst_RS(ir)];
+
+	MIPS_R2_STATS(hilo);
+
+	return 0;
+}
+
+/**
+ * mflo_func - Emulate a MFLO instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int mflo_func(struct pt_regs *regs, u32 ir)
+{
+	if (MIPSInst_RD(ir))
+		regs->regs[MIPSInst_RD(ir)] = regs->lo;
+
+	MIPS_R2_STATS(hilo);
+
+	return 0;
+}
+
+/**
+ * mtlo_func - Emulate a MTLO instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int mtlo_func(struct pt_regs *regs, u32 ir)
+{
+	regs->lo = regs->regs[MIPSInst_RS(ir)];
+
+	MIPS_R2_STATS(hilo);
+
+	return 0;
+}
+
+/**
+ * mult_func - Emulate a MULT instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int mult_func(struct pt_regs *regs, u32 ir)
+{
+	s64 res;
+	s32 rt, rs;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = (s64)rt * (s64)rs;
+
+	rs = res;
+	regs->lo = (s64)rs;
+	rt = res >> 32;
+	res = (s64)rt;
+	regs->hi = res;
+
+	MIPS_R2_STATS(muls);
+
+	return 0;
+}
+
+/**
+ * multu_func - Emulate a MULTU instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int multu_func(struct pt_regs *regs, u32 ir)
+{
+	u64 res;
+	u32 rt, rs;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = (u64)rt * (u64)rs;
+	rt = res;
+	regs->lo = (s64)rt;
+	regs->hi = (s64)(res >> 32);
+
+	MIPS_R2_STATS(muls);
+
+	return 0;
+}
+
+/**
+ * div_func - Emulate a DIV instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int div_func(struct pt_regs *regs, u32 ir)
+{
+	s32 rt, rs;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+
+	regs->lo = (s64)(rs / rt);
+	regs->hi = (s64)(rs % rt);
+
+	MIPS_R2_STATS(divs);
+
+	return 0;
+}
+
+/**
+ * divu_func - Emulate a DIVU instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int divu_func(struct pt_regs *regs, u32 ir)
+{
+	u32 rt, rs;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+
+	regs->lo = (s64)(rs / rt);
+	regs->hi = (s64)(rs % rt);
+
+	MIPS_R2_STATS(divs);
+
+	return 0;
+}
+
+/**
+ * dmult_func - Emulate a DMULT instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 on success or SIGILL for 32-bit kernels.
+ */
+static int dmult_func(struct pt_regs *regs, u32 ir)
+{
+	s64 res;
+	s64 rt, rs;
+
+	if (config_enabled(CONFIG_32BIT))
+		return SIGILL;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = rt * rs;
+
+	regs->lo = res;
+	__asm__ __volatile__(
+		"dmuh %0, %1, %2\t\n"
+		: "=r"(res)
+		: "r"(rt), "r"(rs));
+
+	regs->hi = res;
+
+	MIPS_R2_STATS(muls);
+
+	return 0;
+}
+
+/**
+ * dmultu_func - Emulate a DMULTU instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 on success or SIGILL for 32-bit kernels.
+ */
+static int dmultu_func(struct pt_regs *regs, u32 ir)
+{
+	u64 res;
+	u64 rt, rs;
+
+	if (config_enabled(CONFIG_32BIT))
+		return SIGILL;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = rt * rs;
+
+	regs->lo = res;
+	__asm__ __volatile__(
+		"dmuhu %0, %1, %2\t\n"
+		: "=r"(res)
+		: "r"(rt), "r"(rs));
+
+	regs->hi = res;
+
+	MIPS_R2_STATS(muls);
+
+	return 0;
+}
+
+/**
+ * ddiv_func - Emulate a DDIV instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 on success or SIGILL for 32-bit kernels.
+ */
+static int ddiv_func(struct pt_regs *regs, u32 ir)
+{
+	s64 rt, rs;
+
+	if (config_enabled(CONFIG_32BIT))
+		return SIGILL;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+
+	regs->lo = rs / rt;
+	regs->hi = rs % rt;
+
+	MIPS_R2_STATS(divs);
+
+	return 0;
+}
+
+/**
+ * ddivu_func - Emulate a DDIVU instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 on success or SIGILL for 32-bit kernels.
+ */
+static int ddivu_func(struct pt_regs *regs, u32 ir)
+{
+	u64 rt, rs;
+
+	if (config_enabled(CONFIG_32BIT))
+		return SIGILL;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+
+	regs->lo = rs / rt;
+	regs->hi = rs % rt;
+
+	MIPS_R2_STATS(divs);
+
+	return 0;
+}
+
+/* R6 removed instructions for the SPECIAL opcode */
+static struct r2_decoder_table spec_op_table[] = {
+	{ 0xfc1ff83f, 0x00000008, jr_func },
+	{ 0xfc00ffff, 0x00000018, mult_func },
+	{ 0xfc00ffff, 0x00000019, multu_func },
+	{ 0xfc00ffff, 0x0000001c, dmult_func },
+	{ 0xfc00ffff, 0x0000001d, dmultu_func },
+	{ 0xffff07ff, 0x00000010, mfhi_func },
+	{ 0xfc1fffff, 0x00000011, mthi_func },
+	{ 0xffff07ff, 0x00000012, mflo_func },
+	{ 0xfc1fffff, 0x00000013, mtlo_func },
+	{ 0xfc0307ff, 0x00000001, movf_func },
+	{ 0xfc0307ff, 0x00010001, movt_func },
+	{ 0xfc0007ff, 0x0000000a, movz_func },
+	{ 0xfc0007ff, 0x0000000b, movn_func },
+	{ 0xfc00ffff, 0x0000001a, div_func },
+	{ 0xfc00ffff, 0x0000001b, divu_func },
+	{ 0xfc00ffff, 0x0000001e, ddiv_func },
+	{ 0xfc00ffff, 0x0000001f, ddivu_func },
+	{}
+};
+
+/**
+ * madd_func - Emulate a MADD instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int madd_func(struct pt_regs *regs, u32 ir)
+{
+	s64 res;
+	s32 rt, rs;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = (s64)rt * (s64)rs;
+	rt = regs->hi;
+	rs = regs->lo;
+	res += ((((s64)rt) << 32) | (u32)rs);
+
+	rt = res;
+	regs->lo = (s64)rt;
+	rs = res >> 32;
+	regs->hi = (s64)rs;
+
+	MIPS_R2_STATS(dsps);
+
+	return 0;
+}
+
+/**
+ * maddu_func - Emulate a MADDU instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int maddu_func(struct pt_regs *regs, u32 ir)
+{
+	u64 res;
+	u32 rt, rs;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = (u64)rt * (u64)rs;
+	rt = regs->hi;
+	rs = regs->lo;
+	res += ((((s64)rt) << 32) | (u32)rs);
+
+	rt = res;
+	regs->lo = (s64)rt;
+	rs = res >> 32;
+	regs->hi = (s64)rs;
+
+	MIPS_R2_STATS(dsps);
+
+	return 0;
+}
+
+/**
+ * msub_func - Emulate a MSUB instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int msub_func(struct pt_regs *regs, u32 ir)
+{
+	s64 res;
+	s32 rt, rs;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = (s64)rt * (s64)rs;
+	rt = regs->hi;
+	rs = regs->lo;
+	res = ((((s64)rt) << 32) | (u32)rs) - res;
+
+	rt = res;
+	regs->lo = (s64)rt;
+	rs = res >> 32;
+	regs->hi = (s64)rs;
+
+	MIPS_R2_STATS(dsps);
+
+	return 0;
+}
+
+/**
+ * msubu_func - Emulate a MSUBU instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int msubu_func(struct pt_regs *regs, u32 ir)
+{
+	u64 res;
+	u32 rt, rs;
+
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = (u64)rt * (u64)rs;
+	rt = regs->hi;
+	rs = regs->lo;
+	res = ((((s64)rt) << 32) | (u32)rs) - res;
+
+	rt = res;
+	regs->lo = (s64)rt;
+	rs = res >> 32;
+	regs->hi = (s64)rs;
+
+	MIPS_R2_STATS(dsps);
+
+	return 0;
+}
+
+/**
+ * mul_func - Emulate a MUL instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int mul_func(struct pt_regs *regs, u32 ir)
+{
+	s64 res;
+	s32 rt, rs;
+
+	if (!MIPSInst_RD(ir))
+		return 0;
+	rt = regs->regs[MIPSInst_RT(ir)];
+	rs = regs->regs[MIPSInst_RS(ir)];
+	res = (s64)rt * (s64)rs;
+
+	rs = res;
+	regs->regs[MIPSInst_RD(ir)] = (s64)rs;
+
+	MIPS_R2_STATS(muls);
+
+	return 0;
+}
+
+/**
+ * clz_func - Emulate a CLZ instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int clz_func(struct pt_regs *regs, u32 ir)
+{
+	u32 res;
+	u32 rs;
+
+	if (!MIPSInst_RD(ir))
+		return 0;
+
+	rs = regs->regs[MIPSInst_RS(ir)];
+	__asm__ __volatile__("clz %0, %1" : "=r"(res) : "r"(rs));
+	regs->regs[MIPSInst_RD(ir)] = res;
+
+	MIPS_R2_STATS(bops);
+
+	return 0;
+}
+
+/**
+ * clo_func - Emulate a CLO instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+
+static int clo_func(struct pt_regs *regs, u32 ir)
+{
+	u32 res;
+	u32 rs;
+
+	if (!MIPSInst_RD(ir))
+		return 0;
+
+	rs = regs->regs[MIPSInst_RS(ir)];
+	__asm__ __volatile__("clo %0, %1" : "=r"(res) : "r"(rs));
+	regs->regs[MIPSInst_RD(ir)] = res;
+
+	MIPS_R2_STATS(bops);
+
+	return 0;
+}
+
+/**
+ * dclz_func - Emulate a DCLZ instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int dclz_func(struct pt_regs *regs, u32 ir)
+{
+	u64 res;
+	u64 rs;
+
+	if (config_enabled(CONFIG_32BIT))
+		return SIGILL;
+
+	if (!MIPSInst_RD(ir))
+		return 0;
+
+	rs = regs->regs[MIPSInst_RS(ir)];
+	__asm__ __volatile__("dclz %0, %1" : "=r"(res) : "r"(rs));
+	regs->regs[MIPSInst_RD(ir)] = res;
+
+	MIPS_R2_STATS(bops);
+
+	return 0;
+}
+
+/**
+ * dclo_func - Emulate a DCLO instruction
+ * @regs: Process register set
+ * @ir: Instruction
+ *
+ * Returns 0 since it always succeeds.
+ */
+static int dclo_func(struct pt_regs *regs, u32 ir)
+{
+	u64 res;
+	u64 rs;
+
+	if (config_enabled(CONFIG_32BIT))
+		return SIGILL;
+
+	if (!MIPSInst_RD(ir))
+		return 0;
+
+	rs = regs->regs[MIPSInst_RS(ir)];
+	__asm__ __volatile__("dclo %0, %1" : "=r"(res) : "r"(rs));
+	regs->regs[MIPSInst_RD(ir)] = res;
+
+	MIPS_R2_STATS(bops);
+
+	return 0;
+}
+
+/* R6 removed instructions for the SPECIAL2 opcode */
+static struct r2_decoder_table spec2_op_table[] = {
+	{ 0xfc00ffff, 0x70000000, madd_func },
+	{ 0xfc00ffff, 0x70000001, maddu_func },
+	{ 0xfc0007ff, 0x70000002, mul_func },
+	{ 0xfc00ffff, 0x70000004, msub_func },
+	{ 0xfc00ffff, 0x70000005, msubu_func },
+	{ 0xfc0007ff, 0x70000020, clz_func },
+	{ 0xfc0007ff, 0x70000021, clo_func },
+	{ 0xfc0007ff, 0x70000024, dclz_func },
+	{ 0xfc0007ff, 0x70000025, dclo_func },
+	{ }
+};
+
+static inline int mipsr2_find_op_func(struct pt_regs *regs, u32 inst,
+				      struct r2_decoder_table *table)
+{
+	struct r2_decoder_table *p;
+	int err;
+
+	for (p = table; p->func; p++) {
+		if ((inst & p->mask) == p->code) {
+			err = (p->func)(regs, inst);
+			return err;
+		}
+	}
+	return SIGILL;
+}
+
+/**
+ * mipsr2_decoder: Decode and emulate a MIPS R2 instruction
+ * @regs: Process register set
+ * @inst: Instruction to decode and emulate
+ */
+int mipsr2_decoder(struct pt_regs *regs, u32 inst)
+{
+	int err = 0;
+	unsigned long vaddr;
+	u32 nir;
+	unsigned long cpc, epc, nepc, r31, res, rs, rt;
+
+	void __user *fault_addr = NULL;
+	int pass = 0;
+
+repeat:
+	r31 = regs->regs[31];
+	epc = regs->cp0_epc;
+	err = compute_return_epc(regs);
+	if (err < 0) {
+		BUG();
+		return SIGEMT;
+	}
+	pr_debug("Emulating the 0x%08x R2 instruction @ 0x%08lx (pass=%d))\n",
+		 inst, epc, pass);
+
+	switch (MIPSInst_OPCODE(inst)) {
+	case spec_op:
+		err = mipsr2_find_op_func(regs, inst, spec_op_table);
+		if (err < 0) {
+			/* FPU instruction under JR */
+			regs->cp0_cause |= CAUSEF_BD;
+			goto fpu_emul;
+		}
+		break;
+	case spec2_op:
+		err = mipsr2_find_op_func(regs, inst, spec2_op_table);
+		break;
+	case bcond_op:
+		rt = MIPSInst_RT(inst);
+		rs = MIPSInst_RS(inst);
+		switch (rt) {
+		case tgei_op:
+			if ((long)regs->regs[rs] >= MIPSInst_SIMM(inst))
+				do_trap_or_bp(regs, 0, "TGEI");
+
+			MIPS_R2_STATS(traps);
+
+			break;
+		case tgeiu_op:
+			if (regs->regs[rs] >= MIPSInst_UIMM(inst))
+				do_trap_or_bp(regs, 0, "TGEIU");
+
+			MIPS_R2_STATS(traps);
+
+			break;
+		case tlti_op:
+			if ((long)regs->regs[rs] < MIPSInst_SIMM(inst))
+				do_trap_or_bp(regs, 0, "TLTI");
+
+			MIPS_R2_STATS(traps);
+
+			break;
+		case tltiu_op:
+			if (regs->regs[rs] < MIPSInst_UIMM(inst))
+				do_trap_or_bp(regs, 0, "TLTIU");
+
+			MIPS_R2_STATS(traps);
+
+			break;
+		case teqi_op:
+			if (regs->regs[rs] == MIPSInst_SIMM(inst))
+				do_trap_or_bp(regs, 0, "TEQI");
+
+			MIPS_R2_STATS(traps);
+
+			break;
+		case tnei_op:
+			if (regs->regs[rs] != MIPSInst_SIMM(inst))
+				do_trap_or_bp(regs, 0, "TNEI");
+
+			MIPS_R2_STATS(traps);
+
+			break;
+		case bltzl_op:
+		case bgezl_op:
+		case bltzall_op:
+		case bgezall_op:
+			if (delay_slot(regs)) {
+				err = SIGILL;
+				break;
+			}
+			regs->regs[31] = r31;
+			regs->cp0_epc = epc;
+			err = __compute_return_epc(regs);
+			if (err < 0)
+				return SIGEMT;
+			if (err != BRANCH_LIKELY_TAKEN)
+				break;
+			cpc = regs->cp0_epc;
+			nepc = epc + 4;
+			err = __get_user(nir, (u32 __user *)nepc);
+			if (err) {
+				err = SIGSEGV;
+				break;
+			}
+			/*
+			 * This will probably be optimized away when
+			 * CONFIG_DEBUG_FS is not enabled
+			 */
+			switch (rt) {
+			case bltzl_op:
+				MIPS_R2BR_STATS(bltzl);
+				break;
+			case bgezl_op:
+				MIPS_R2BR_STATS(bgezl);
+				break;
+			case bltzall_op:
+				MIPS_R2BR_STATS(bltzall);
+				break;
+			case bgezall_op:
+				MIPS_R2BR_STATS(bgezall);
+				break;
+			}
+
+			switch (MIPSInst_OPCODE(nir)) {
+			case cop1_op:
+			case cop1x_op:
+			case lwc1_op:
+			case swc1_op:
+				regs->cp0_cause |= CAUSEF_BD;
+				goto fpu_emul;
+			}
+			if (nir) {
+				err = mipsr6_emul(regs, nir);
+				if (err > 0) {
+					err = mips_dsemul(regs, nir, cpc);
+					if (err == SIGILL)
+						err = SIGEMT;
+					MIPS_R2_STATS(dsemul);
+				}
+			}
+			break;
+		case bltzal_op:
+		case bgezal_op:
+			if (delay_slot(regs)) {
+				err = SIGILL;
+				break;
+			}
+			regs->regs[31] = r31;
+			regs->cp0_epc = epc;
+			err = __compute_return_epc(regs);
+			if (err < 0)
+				return SIGEMT;
+			cpc = regs->cp0_epc;
+			nepc = epc + 4;
+			err = __get_user(nir, (u32 __user *)nepc);
+			if (err) {
+				err = SIGSEGV;
+				break;
+			}
+			/*
+			 * This will probably be optimized away when
+			 * CONFIG_DEBUG_FS is not enabled
+			 */
+			switch (rt) {
+			case bltzal_op:
+				MIPS_R2BR_STATS(bltzal);
+				break;
+			case bgezal_op:
+				MIPS_R2BR_STATS(bgezal);
+				break;
+			}
+
+			switch (MIPSInst_OPCODE(nir)) {
+			case cop1_op:
+			case cop1x_op:
+			case lwc1_op:
+			case swc1_op:
+				regs->cp0_cause |= CAUSEF_BD;
+				goto fpu_emul;
+			}
+			if (nir) {
+				err = mipsr6_emul(regs, nir);
+				if (err > 0) {
+					err = mips_dsemul(regs, nir, cpc);
+					if (err == SIGILL)
+						err = SIGEMT;
+					MIPS_R2_STATS(dsemul);
+				}
+			}
+			break;
+		default:
+			regs->regs[31] = r31;
+			regs->cp0_epc = epc;
+			err = SIGILL;
+			break;
+		}
+		break;
+
+	case beql_op:
+	case bnel_op:
+	case blezl_op:
+	case bgtzl_op:
+		if (delay_slot(regs)) {
+			err = SIGILL;
+			break;
+		}
+		regs->regs[31] = r31;
+		regs->cp0_epc = epc;
+		err = __compute_return_epc(regs);
+		if (err < 0)
+			return SIGEMT;
+		if (err != BRANCH_LIKELY_TAKEN)
+			break;
+		cpc = regs->cp0_epc;
+		nepc = epc + 4;
+		err = __get_user(nir, (u32 __user *)nepc);
+		if (err) {
+			err = SIGSEGV;
+			break;
+		}
+		/*
+		 * This will probably be optimized away when
+		 * CONFIG_DEBUG_FS is not enabled
+		 */
+		switch (MIPSInst_OPCODE(inst)) {
+		case beql_op:
+			MIPS_R2BR_STATS(beql);
+			break;
+		case bnel_op:
+			MIPS_R2BR_STATS(bnel);
+			break;
+		case blezl_op:
+			MIPS_R2BR_STATS(blezl);
+			break;
+		case bgtzl_op:
+			MIPS_R2BR_STATS(bgtzl);
+			break;
+		}
+
+		switch (MIPSInst_OPCODE(nir)) {
+		case cop1_op:
+		case cop1x_op:
+		case lwc1_op:
+		case swc1_op:
+			regs->cp0_cause |= CAUSEF_BD;
+			goto fpu_emul;
+		}
+		if (nir) {
+			err = mipsr6_emul(regs, nir);
+			if (err > 0) {
+				err = mips_dsemul(regs, nir, cpc);
+				if (err == SIGILL)
+					err = SIGEMT;
+				MIPS_R2_STATS(dsemul);
+			}
+		}
+		break;
+	case lwc1_op:
+	case swc1_op:
+	case cop1_op:
+	case cop1x_op:
+fpu_emul:
+		regs->regs[31] = r31;
+		regs->cp0_epc = epc;
+		if (!used_math()) {     /* First time FPU user.  */
+			err = init_fpu();
+			set_used_math();
+		}
+		lose_fpu(1);    /* Save FPU state for the emulator. */
+
+		err = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 0,
+					       &fault_addr);
+
+		/*
+		 * this is a tricky issue - lose_fpu() uses LL/SC atomics
+		 * if FPU is owned and effectively cancels user level LL/SC.
+		 * So, it could be logical to don't restore FPU ownership here.
+		 * But the sequence of multiple FPU instructions is much much
+		 * more often than LL-FPU-SC and I prefer loop here until
+		 * next scheduler cycle cancels FPU ownership
+		 */
+		own_fpu(1);	/* Restore FPU state. */
+
+		if (err)
+			current->thread.cp0_baduaddr = (unsigned long)fault_addr;
+
+		MIPS_R2_STATS(fpus);
+
+		break;
+
+	case lwl_op:
+		rt = regs->regs[MIPSInst_RT(inst)];
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (!access_ok(VERIFY_READ, vaddr, 4)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGSEGV;
+			break;
+		}
+		__asm__ __volatile__(
+			"	.set	push\n"
+			"	.set	reorder\n"
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+			"1:"	LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 24, 8\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+			"2:"	LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 16, 8\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+			"3:"	LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 8, 8\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+			"4:"	LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 0, 8\n"
+#else /* !CONFIG_CPU_LITTLE_ENDIAN */
+			"1:"	LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 24, 8\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+			"2:"	LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 16, 8\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+			"3:"	LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 8, 8\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+			"4:"	LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 0, 8\n"
+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
+			"9:	sll	%0, %0, 0\n"
+			"10:\n"
+			"	.insn\n"
+			"	.section	.fixup,\"ax\"\n"
+			"8:	li	%3,%4\n"
+			"	j	10b\n"
+			"	.previous\n"
+			"	.section	__ex_table,\"a\"\n"
+			"	.word	1b,8b\n"
+			"	.word	2b,8b\n"
+			"	.word	3b,8b\n"
+			"	.word	4b,8b\n"
+			"	.previous\n"
+			"	.set	pop\n"
+			: "+&r"(rt), "=&r"(rs),
+			  "+&r"(vaddr), "+&r"(err)
+			: "i"(SIGSEGV));
+
+		if (MIPSInst_RT(inst) && !err)
+			regs->regs[MIPSInst_RT(inst)] = rt;
+
+		MIPS_R2_STATS(loads);
+
+		break;
+
+	case lwr_op:
+		rt = regs->regs[MIPSInst_RT(inst)];
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (!access_ok(VERIFY_READ, vaddr, 4)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGSEGV;
+			break;
+		}
+		__asm__ __volatile__(
+			"       .set	push\n"
+			"       .set	reorder\n"
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+			"1:"    LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 0, 8\n"
+				ADDIU	"%2, %2, 1\n"
+			"       andi	%1, %2, 0x3\n"
+			"       beq	$0, %1, 9f\n"
+			"2:"    LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 8, 8\n"
+				ADDIU	"%2, %2, 1\n"
+			"       andi	%1, %2, 0x3\n"
+			"       beq	$0, %1, 9f\n"
+			"3:"    LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 16, 8\n"
+				ADDIU	"%2, %2, 1\n"
+			"       andi	%1, %2, 0x3\n"
+			"       beq	$0, %1, 9f\n"
+			"4:"    LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 24, 8\n"
+			"       sll	%0, %0, 0\n"
+#else /* !CONFIG_CPU_LITTLE_ENDIAN */
+			"1:"    LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 0, 8\n"
+			"       andi	%1, %2, 0x3\n"
+			"       beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+			"2:"    LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 8, 8\n"
+			"       andi	%1, %2, 0x3\n"
+			"       beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+			"3:"    LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 16, 8\n"
+			"       andi	%1, %2, 0x3\n"
+			"       beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+			"4:"    LB	"%1, 0(%2)\n"
+				INS	"%0, %1, 24, 8\n"
+			"       sll	%0, %0, 0\n"
+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
+			"9:\n"
+			"10:\n"
+			"	.insn\n"
+			"	.section	.fixup,\"ax\"\n"
+			"8:	li	%3,%4\n"
+			"	j	10b\n"
+			"       .previous\n"
+			"	.section	__ex_table,\"a\"\n"
+			"	.word	1b,8b\n"
+			"	.word	2b,8b\n"
+			"	.word	3b,8b\n"
+			"	.word	4b,8b\n"
+			"	.previous\n"
+			"	.set	pop\n"
+			: "+&r"(rt), "=&r"(rs),
+			  "+&r"(vaddr), "+&r"(err)
+			: "i"(SIGSEGV));
+		if (MIPSInst_RT(inst) && !err)
+			regs->regs[MIPSInst_RT(inst)] = rt;
+
+		MIPS_R2_STATS(loads);
+
+		break;
+
+	case swl_op:
+		rt = regs->regs[MIPSInst_RT(inst)];
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (!access_ok(VERIFY_WRITE, vaddr, 4)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGSEGV;
+			break;
+		}
+		__asm__ __volatile__(
+			"	.set	push\n"
+			"	.set	reorder\n"
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+				EXT	"%1, %0, 24, 8\n"
+			"1:"	SB	"%1, 0(%2)\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+				EXT	"%1, %0, 16, 8\n"
+			"2:"	SB	"%1, 0(%2)\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+				EXT	"%1, %0, 8, 8\n"
+			"3:"	SB	"%1, 0(%2)\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+				EXT	"%1, %0, 0, 8\n"
+			"4:"	SB	"%1, 0(%2)\n"
+#else /* !CONFIG_CPU_LITTLE_ENDIAN */
+				EXT	"%1, %0, 24, 8\n"
+			"1:"	SB	"%1, 0(%2)\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				EXT	"%1, %0, 16, 8\n"
+			"2:"	SB	"%1, 0(%2)\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				EXT	"%1, %0, 8, 8\n"
+			"3:"	SB	"%1, 0(%2)\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				EXT	"%1, %0, 0, 8\n"
+			"4:"	SB	"%1, 0(%2)\n"
+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
+			"9:\n"
+			"	.insn\n"
+			"       .section        .fixup,\"ax\"\n"
+			"8:	li	%3,%4\n"
+			"	j	9b\n"
+			"	.previous\n"
+			"	.section        __ex_table,\"a\"\n"
+			"	.word	1b,8b\n"
+			"	.word	2b,8b\n"
+			"	.word	3b,8b\n"
+			"	.word	4b,8b\n"
+			"	.previous\n"
+			"	.set	pop\n"
+			: "+&r"(rt), "=&r"(rs),
+			  "+&r"(vaddr), "+&r"(err)
+			: "i"(SIGSEGV)
+			: "memory");
+
+		MIPS_R2_STATS(stores);
+
+		break;
+
+	case swr_op:
+		rt = regs->regs[MIPSInst_RT(inst)];
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (!access_ok(VERIFY_WRITE, vaddr, 4)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGSEGV;
+			break;
+		}
+		__asm__ __volatile__(
+			"	.set	push\n"
+			"	.set	reorder\n"
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+				EXT	"%1, %0, 0, 8\n"
+			"1:"	SB	"%1, 0(%2)\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				EXT	"%1, %0, 8, 8\n"
+			"2:"	SB	"%1, 0(%2)\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				EXT	"%1, %0, 16, 8\n"
+			"3:"	SB	"%1, 0(%2)\n"
+				ADDIU	"%2, %2, 1\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				EXT	"%1, %0, 24, 8\n"
+			"4:"	SB	"%1, 0(%2)\n"
+#else /* !CONFIG_CPU_LITTLE_ENDIAN */
+				EXT	"%1, %0, 0, 8\n"
+			"1:"	SB	"%1, 0(%2)\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+				EXT	"%1, %0, 8, 8\n"
+			"2:"	SB	"%1, 0(%2)\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+				EXT	"%1, %0, 16, 8\n"
+			"3:"	SB	"%1, 0(%2)\n"
+			"	andi	%1, %2, 0x3\n"
+			"	beq	$0, %1, 9f\n"
+				ADDIU	"%2, %2, -1\n"
+				EXT	"%1, %0, 24, 8\n"
+			"4:"	SB	"%1, 0(%2)\n"
+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
+			"9:\n"
+			"	.insn\n"
+			"	.section        .fixup,\"ax\"\n"
+			"8:	li	%3,%4\n"
+			"	j	9b\n"
+			"	.previous\n"
+			"	.section        __ex_table,\"a\"\n"
+			"	.word	1b,8b\n"
+			"	.word	2b,8b\n"
+			"	.word	3b,8b\n"
+			"	.word	4b,8b\n"
+			"	.previous\n"
+			"	.set	pop\n"
+			: "+&r"(rt), "=&r"(rs),
+			  "+&r"(vaddr), "+&r"(err)
+			: "i"(SIGSEGV)
+			: "memory");
+
+		MIPS_R2_STATS(stores);
+
+		break;
+
+	case ldl_op:
+		if (config_enabled(CONFIG_32BIT)) {
+		    err = SIGILL;
+		    break;
+		}
+
+		rt = regs->regs[MIPSInst_RT(inst)];
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (!access_ok(VERIFY_READ, vaddr, 8)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGSEGV;
+			break;
+		}
+		__asm__ __volatile__(
+			"	.set    push\n"
+			"	.set    reorder\n"
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+			"1:	lb	%1, 0(%2)\n"
+			"	dinsu	%0, %1, 56, 8\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"2:	lb	%1, 0(%2)\n"
+			"	dinsu	%0, %1, 48, 8\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"3:	lb	%1, 0(%2)\n"
+			"	dinsu	%0, %1, 40, 8\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"4:	lb	%1, 0(%2)\n"
+			"	dinsu	%0, %1, 32, 8\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"5:	lb	%1, 0(%2)\n"
+			"	dins	%0, %1, 24, 8\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"6:	lb	%1, 0(%2)\n"
+			"	dins	%0, %1, 16, 8\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"7:	lb	%1, 0(%2)\n"
+			"	dins	%0, %1, 8, 8\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"0:	lb	%1, 0(%2)\n"
+			"	dins	%0, %1, 0, 8\n"
+#else /* !CONFIG_CPU_LITTLE_ENDIAN */
+			"1:	lb	%1, 0(%2)\n"
+			"	dinsu	%0, %1, 56, 8\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"2:	lb	%1, 0(%2)\n"
+			"	dinsu	%0, %1, 48, 8\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"3:	lb	%1, 0(%2)\n"
+			"	dinsu	%0, %1, 40, 8\n"
+			"	daddiu  %2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"4:	lb	%1, 0(%2)\n"
+			"	dinsu	%0, %1, 32, 8\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"5:	lb	%1, 0(%2)\n"
+			"	dins	%0, %1, 24, 8\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"6:	lb	%1, 0(%2)\n"
+			"	dins	%0, %1, 16, 8\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"7:	lb	%1, 0(%2)\n"
+			"	dins	%0, %1, 8, 8\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"0:	lb	%1, 0(%2)\n"
+			"	dins	%0, %1, 0, 8\n"
+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
+			"9:\n"
+			"	.insn\n"
+			"	.section        .fixup,\"ax\"\n"
+			"8:	li	%3,%4\n"
+			"	j	9b\n"
+			"	.previous\n"
+			"	.section        __ex_table,\"a\"\n"
+			"	.word	1b,8b\n"
+			"	.word	2b,8b\n"
+			"	.word	3b,8b\n"
+			"	.word	4b,8b\n"
+			"	.word	5b,8b\n"
+			"	.word	6b,8b\n"
+			"	.word	7b,8b\n"
+			"	.word	0b,8b\n"
+			"	.previous\n"
+			"	.set	pop\n"
+			: "+&r"(rt), "=&r"(rs),
+			  "+&r"(vaddr), "+&r"(err)
+			: "i"(SIGSEGV));
+		if (MIPSInst_RT(inst) && !err)
+			regs->regs[MIPSInst_RT(inst)] = rt;
+
+		MIPS_R2_STATS(loads);
+		break;
+
+	case ldr_op:
+		if (config_enabled(CONFIG_32BIT)) {
+		    err = SIGILL;
+		    break;
+		}
+
+		rt = regs->regs[MIPSInst_RT(inst)];
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (!access_ok(VERIFY_READ, vaddr, 8)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGSEGV;
+			break;
+		}
+		__asm__ __volatile__(
+			"	.set    push\n"
+			"	.set    reorder\n"
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+			"1:	lb      %1, 0(%2)\n"
+			"	dins   %0, %1, 0, 8\n"
+			"	daddiu  %2, %2, 1\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"2:	lb      %1, 0(%2)\n"
+			"	dins   %0, %1, 8, 8\n"
+			"	daddiu  %2, %2, 1\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"3:	lb      %1, 0(%2)\n"
+			"	dins   %0, %1, 16, 8\n"
+			"	daddiu  %2, %2, 1\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"4:	lb      %1, 0(%2)\n"
+			"	dins   %0, %1, 24, 8\n"
+			"	daddiu  %2, %2, 1\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"5:	lb      %1, 0(%2)\n"
+			"	dinsu    %0, %1, 32, 8\n"
+			"	daddiu  %2, %2, 1\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"6:	lb      %1, 0(%2)\n"
+			"	dinsu    %0, %1, 40, 8\n"
+			"	daddiu  %2, %2, 1\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"7:	lb      %1, 0(%2)\n"
+			"	dinsu    %0, %1, 48, 8\n"
+			"	daddiu  %2, %2, 1\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"0:	lb      %1, 0(%2)\n"
+			"	dinsu    %0, %1, 56, 8\n"
+#else /* !CONFIG_CPU_LITTLE_ENDIAN */
+			"1:	lb      %1, 0(%2)\n"
+			"	dins   %0, %1, 0, 8\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"	daddiu  %2, %2, -1\n"
+			"2:	lb      %1, 0(%2)\n"
+			"	dins   %0, %1, 8, 8\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"	daddiu  %2, %2, -1\n"
+			"3:	lb      %1, 0(%2)\n"
+			"	dins   %0, %1, 16, 8\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"	daddiu  %2, %2, -1\n"
+			"4:	lb      %1, 0(%2)\n"
+			"	dins   %0, %1, 24, 8\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"	daddiu  %2, %2, -1\n"
+			"5:	lb      %1, 0(%2)\n"
+			"	dinsu    %0, %1, 32, 8\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"	daddiu  %2, %2, -1\n"
+			"6:	lb      %1, 0(%2)\n"
+			"	dinsu    %0, %1, 40, 8\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"	daddiu  %2, %2, -1\n"
+			"7:	lb      %1, 0(%2)\n"
+			"	dinsu    %0, %1, 48, 8\n"
+			"	andi    %1, %2, 0x7\n"
+			"	beq     $0, %1, 9f\n"
+			"	daddiu  %2, %2, -1\n"
+			"0:	lb      %1, 0(%2)\n"
+			"	dinsu    %0, %1, 56, 8\n"
+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
+			"9:\n"
+			"	.insn\n"
+			"	.section        .fixup,\"ax\"\n"
+			"8:	li     %3,%4\n"
+			"	j      9b\n"
+			"	.previous\n"
+			"	.section        __ex_table,\"a\"\n"
+			"	.word  1b,8b\n"
+			"	.word  2b,8b\n"
+			"	.word  3b,8b\n"
+			"	.word  4b,8b\n"
+			"	.word  5b,8b\n"
+			"	.word  6b,8b\n"
+			"	.word  7b,8b\n"
+			"	.word  0b,8b\n"
+			"	.previous\n"
+			"	.set    pop\n"
+			: "+&r"(rt), "=&r"(rs),
+			  "+&r"(vaddr), "+&r"(err)
+			: "i"(SIGSEGV));
+		if (MIPSInst_RT(inst) && !err)
+			regs->regs[MIPSInst_RT(inst)] = rt;
+
+		MIPS_R2_STATS(loads);
+		break;
+
+	case sdl_op:
+		if (config_enabled(CONFIG_32BIT)) {
+		    err = SIGILL;
+		    break;
+		}
+
+		rt = regs->regs[MIPSInst_RT(inst)];
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (!access_ok(VERIFY_WRITE, vaddr, 8)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGSEGV;
+			break;
+		}
+		__asm__ __volatile__(
+			"	.set	push\n"
+			"	.set	reorder\n"
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+			"	dextu	%1, %0, 56, 8\n"
+			"1:	sb	%1, 0(%2)\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"	dextu	%1, %0, 48, 8\n"
+			"2:	sb	%1, 0(%2)\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"	dextu	%1, %0, 40, 8\n"
+			"3:	sb	%1, 0(%2)\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"	dextu	%1, %0, 32, 8\n"
+			"4:	sb	%1, 0(%2)\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"	dext	%1, %0, 24, 8\n"
+			"5:	sb	%1, 0(%2)\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"	dext	%1, %0, 16, 8\n"
+			"6:	sb	%1, 0(%2)\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"	dext	%1, %0, 8, 8\n"
+			"7:	sb	%1, 0(%2)\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	daddiu	%2, %2, -1\n"
+			"	dext	%1, %0, 0, 8\n"
+			"0:	sb	%1, 0(%2)\n"
+#else /* !CONFIG_CPU_LITTLE_ENDIAN */
+			"	dextu	%1, %0, 56, 8\n"
+			"1:	sb	%1, 0(%2)\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	dextu	%1, %0, 48, 8\n"
+			"2:	sb	%1, 0(%2)\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	dextu	%1, %0, 40, 8\n"
+			"3:	sb	%1, 0(%2)\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	dextu	%1, %0, 32, 8\n"
+			"4:	sb	%1, 0(%2)\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	dext	%1, %0, 24, 8\n"
+			"5:	sb	%1, 0(%2)\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	dext	%1, %0, 16, 8\n"
+			"6:	sb	%1, 0(%2)\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	dext	%1, %0, 8, 8\n"
+			"7:	sb	%1, 0(%2)\n"
+			"	daddiu	%2, %2, 1\n"
+			"	andi	%1, %2, 0x7\n"
+			"	beq	$0, %1, 9f\n"
+			"	dext	%1, %0, 0, 8\n"
+			"0:	sb	%1, 0(%2)\n"
+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
+			"9:\n"
+			"	.insn\n"
+			"	.section        .fixup,\"ax\"\n"
+			"8:	li	%3,%4\n"
+			"	j	9b\n"
+			"	.previous\n"
+			"	.section        __ex_table,\"a\"\n"
+			"	.word	1b,8b\n"
+			"	.word	2b,8b\n"
+			"	.word	3b,8b\n"
+			"	.word	4b,8b\n"
+			"	.word	5b,8b\n"
+			"	.word	6b,8b\n"
+			"	.word	7b,8b\n"
+			"	.word	0b,8b\n"
+			"	.previous\n"
+			"	.set	pop\n"
+			: "+&r"(rt), "=&r"(rs),
+			  "+&r"(vaddr), "+&r"(err)
+			: "i"(SIGSEGV)
+			: "memory");
+
+		MIPS_R2_STATS(stores);
+		break;
+
+	case sdr_op:
+		if (config_enabled(CONFIG_32BIT)) {
+		    err = SIGILL;
+		    break;
+		}
+
+		rt = regs->regs[MIPSInst_RT(inst)];
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (!access_ok(VERIFY_WRITE, vaddr, 8)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGSEGV;
+			break;
+		}
+		__asm__ __volatile__(
+			"       .set	push\n"
+			"       .set	reorder\n"
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+			"       dext	%1, %0, 0, 8\n"
+			"1:     sb	%1, 0(%2)\n"
+			"       daddiu	%2, %2, 1\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       dext	%1, %0, 8, 8\n"
+			"2:     sb	%1, 0(%2)\n"
+			"       daddiu	%2, %2, 1\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       dext	%1, %0, 16, 8\n"
+			"3:     sb	%1, 0(%2)\n"
+			"       daddiu	%2, %2, 1\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       dext	%1, %0, 24, 8\n"
+			"4:     sb	%1, 0(%2)\n"
+			"       daddiu	%2, %2, 1\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       dextu	%1, %0, 32, 8\n"
+			"5:     sb	%1, 0(%2)\n"
+			"       daddiu	%2, %2, 1\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       dextu	%1, %0, 40, 8\n"
+			"6:     sb	%1, 0(%2)\n"
+			"       daddiu	%2, %2, 1\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       dextu	%1, %0, 48, 8\n"
+			"7:     sb	%1, 0(%2)\n"
+			"       daddiu	%2, %2, 1\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       dextu	%1, %0, 56, 8\n"
+			"0:     sb	%1, 0(%2)\n"
+#else /* !CONFIG_CPU_LITTLE_ENDIAN */
+			"       dext	%1, %0, 0, 8\n"
+			"1:     sb	%1, 0(%2)\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       daddiu	%2, %2, -1\n"
+			"       dext	%1, %0, 8, 8\n"
+			"2:     sb	%1, 0(%2)\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       daddiu	%2, %2, -1\n"
+			"       dext	%1, %0, 16, 8\n"
+			"3:     sb	%1, 0(%2)\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       daddiu	%2, %2, -1\n"
+			"       dext	%1, %0, 24, 8\n"
+			"4:     sb	%1, 0(%2)\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       daddiu	%2, %2, -1\n"
+			"       dextu	%1, %0, 32, 8\n"
+			"5:     sb	%1, 0(%2)\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       daddiu	%2, %2, -1\n"
+			"       dextu	%1, %0, 40, 8\n"
+			"6:     sb	%1, 0(%2)\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       daddiu	%2, %2, -1\n"
+			"       dextu	%1, %0, 48, 8\n"
+			"7:     sb	%1, 0(%2)\n"
+			"       andi	%1, %2, 0x7\n"
+			"       beq	$0, %1, 9f\n"
+			"       daddiu	%2, %2, -1\n"
+			"       dextu	%1, %0, 56, 8\n"
+			"0:     sb	%1, 0(%2)\n"
+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
+			"9:\n"
+			"       .insn\n"
+			"       .section        .fixup,\"ax\"\n"
+			"8:     li	%3,%4\n"
+			"       j	9b\n"
+			"       .previous\n"
+			"       .section        __ex_table,\"a\"\n"
+			"       .word	1b,8b\n"
+			"       .word	2b,8b\n"
+			"       .word	3b,8b\n"
+			"       .word	4b,8b\n"
+			"       .word	5b,8b\n"
+			"       .word	6b,8b\n"
+			"       .word	7b,8b\n"
+			"       .word	0b,8b\n"
+			"       .previous\n"
+			"       .set	pop\n"
+			: "+&r"(rt), "=&r"(rs),
+			  "+&r"(vaddr), "+&r"(err)
+			: "i"(SIGSEGV)
+			: "memory");
+
+		MIPS_R2_STATS(stores);
+
+		break;
+	case ll_op:
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (vaddr & 0x3) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGBUS;
+			break;
+		}
+		if (!access_ok(VERIFY_READ, vaddr, 4)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGBUS;
+			break;
+		}
+
+		if (!cpu_has_rw_llb) {
+			/*
+			 * An LL/SC block can't be safely emulated without
+			 * a Config5/LLB availability. So it's probably time to
+			 * kill our process before things get any worse. This is
+			 * because Config5/LLB allows us to use ERETNC so that
+			 * the LLAddr/LLB bit is not cleared when we return from
+			 * an exception. MIPS R2 LL/SC instructions trap with an
+			 * RI exception so once we emulate them here, we return
+			 * back to userland with ERETNC. That preserves the
+			 * LLAddr/LLB so the subsequent SC instruction will
+			 * succeed preserving the atomic semantics of the LL/SC
+			 * block. Without that, there is no safe way to emulate
+			 * an LL/SC block in MIPSR2 userland.
+			 */
+			pr_err("Can't emulate MIPSR2 LL/SC without Config5/LLB\n");
+			err = SIGKILL;
+			break;
+		}
+
+		__asm__ __volatile__(
+			"1:\n"
+			"ll	%0, 0(%2)\n"
+			"2:\n"
+			".insn\n"
+			".section        .fixup,\"ax\"\n"
+			"3:\n"
+			"li	%1, %3\n"
+			"j	2b\n"
+			".previous\n"
+			".section        __ex_table,\"a\"\n"
+			".word  1b, 3b\n"
+			".previous\n"
+			: "=&r"(res), "+&r"(err)
+			: "r"(vaddr), "i"(SIGSEGV)
+			: "memory");
+
+		if (MIPSInst_RT(inst) && !err)
+			regs->regs[MIPSInst_RT(inst)] = res;
+		MIPS_R2_STATS(llsc);
+
+		break;
+
+	case sc_op:
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (vaddr & 0x3) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGBUS;
+			break;
+		}
+		if (!access_ok(VERIFY_WRITE, vaddr, 4)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGBUS;
+			break;
+		}
+
+		if (!cpu_has_rw_llb) {
+			/*
+			 * An LL/SC block can't be safely emulated without
+			 * a Config5/LLB availability. So it's probably time to
+			 * kill our process before things get any worse. This is
+			 * because Config5/LLB allows us to use ERETNC so that
+			 * the LLAddr/LLB bit is not cleared when we return from
+			 * an exception. MIPS R2 LL/SC instructions trap with an
+			 * RI exception so once we emulate them here, we return
+			 * back to userland with ERETNC. That preserves the
+			 * LLAddr/LLB so the subsequent SC instruction will
+			 * succeed preserving the atomic semantics of the LL/SC
+			 * block. Without that, there is no safe way to emulate
+			 * an LL/SC block in MIPSR2 userland.
+			 */
+			pr_err("Can't emulate MIPSR2 LL/SC without Config5/LLB\n");
+			err = SIGKILL;
+			break;
+		}
+
+		res = regs->regs[MIPSInst_RT(inst)];
+
+		__asm__ __volatile__(
+			"1:\n"
+			"sc	%0, 0(%2)\n"
+			"2:\n"
+			".insn\n"
+			".section        .fixup,\"ax\"\n"
+			"3:\n"
+			"li	%1, %3\n"
+			"j	2b\n"
+			".previous\n"
+			".section        __ex_table,\"a\"\n"
+			".word	1b, 3b\n"
+			".previous\n"
+			: "+&r"(res), "+&r"(err)
+			: "r"(vaddr), "i"(SIGSEGV));
+
+		if (MIPSInst_RT(inst) && !err)
+			regs->regs[MIPSInst_RT(inst)] = res;
+
+		MIPS_R2_STATS(llsc);
+
+		break;
+
+	case lld_op:
+		if (config_enabled(CONFIG_32BIT)) {
+		    err = SIGILL;
+		    break;
+		}
+
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (vaddr & 0x7) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGBUS;
+			break;
+		}
+		if (!access_ok(VERIFY_READ, vaddr, 8)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGBUS;
+			break;
+		}
+
+		if (!cpu_has_rw_llb) {
+			/*
+			 * An LL/SC block can't be safely emulated without
+			 * a Config5/LLB availability. So it's probably time to
+			 * kill our process before things get any worse. This is
+			 * because Config5/LLB allows us to use ERETNC so that
+			 * the LLAddr/LLB bit is not cleared when we return from
+			 * an exception. MIPS R2 LL/SC instructions trap with an
+			 * RI exception so once we emulate them here, we return
+			 * back to userland with ERETNC. That preserves the
+			 * LLAddr/LLB so the subsequent SC instruction will
+			 * succeed preserving the atomic semantics of the LL/SC
+			 * block. Without that, there is no safe way to emulate
+			 * an LL/SC block in MIPSR2 userland.
+			 */
+			pr_err("Can't emulate MIPSR2 LL/SC without Config5/LLB\n");
+			err = SIGKILL;
+			break;
+		}
+
+		__asm__ __volatile__(
+			"1:\n"
+			"lld	%0, 0(%2)\n"
+			"2:\n"
+			".insn\n"
+			".section        .fixup,\"ax\"\n"
+			"3:\n"
+			"li	%1, %3\n"
+			"j	2b\n"
+			".previous\n"
+			".section        __ex_table,\"a\"\n"
+			".word  1b, 3b\n"
+			".previous\n"
+			: "=&r"(res), "+&r"(err)
+			: "r"(vaddr), "i"(SIGSEGV)
+			: "memory");
+		if (MIPSInst_RT(inst) && !err)
+			regs->regs[MIPSInst_RT(inst)] = res;
+
+		MIPS_R2_STATS(llsc);
+
+		break;
+
+	case scd_op:
+		if (config_enabled(CONFIG_32BIT)) {
+		    err = SIGILL;
+		    break;
+		}
+
+		vaddr = regs->regs[MIPSInst_RS(inst)] + MIPSInst_SIMM(inst);
+		if (vaddr & 0x7) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGBUS;
+			break;
+		}
+		if (!access_ok(VERIFY_WRITE, vaddr, 8)) {
+			current->thread.cp0_baduaddr = vaddr;
+			err = SIGBUS;
+			break;
+		}
+
+		if (!cpu_has_rw_llb) {
+			/*
+			 * An LL/SC block can't be safely emulated without
+			 * a Config5/LLB availability. So it's probably time to
+			 * kill our process before things get any worse. This is
+			 * because Config5/LLB allows us to use ERETNC so that
+			 * the LLAddr/LLB bit is not cleared when we return from
+			 * an exception. MIPS R2 LL/SC instructions trap with an
+			 * RI exception so once we emulate them here, we return
+			 * back to userland with ERETNC. That preserves the
+			 * LLAddr/LLB so the subsequent SC instruction will
+			 * succeed preserving the atomic semantics of the LL/SC
+			 * block. Without that, there is no safe way to emulate
+			 * an LL/SC block in MIPSR2 userland.
+			 */
+			pr_err("Can't emulate MIPSR2 LL/SC without Config5/LLB\n");
+			err = SIGKILL;
+			break;
+		}
+
+		res = regs->regs[MIPSInst_RT(inst)];
+
+		__asm__ __volatile__(
+			"1:\n"
+			"scd	%0, 0(%2)\n"
+			"2:\n"
+			".insn\n"
+			".section        .fixup,\"ax\"\n"
+			"3:\n"
+			"li	%1, %3\n"
+			"j	2b\n"
+			".previous\n"
+			".section        __ex_table,\"a\"\n"
+			".word	1b, 3b\n"
+			".previous\n"
+			: "+&r"(res), "+&r"(err)
+			: "r"(vaddr), "i"(SIGSEGV));
+
+		if (MIPSInst_RT(inst) && !err)
+			regs->regs[MIPSInst_RT(inst)] = res;
+
+		MIPS_R2_STATS(llsc);
+
+		break;
+	case pref_op:
+		/* skip it */
+		break;
+	default:
+		err = SIGILL;
+	}
+
+	/*
+	 * Lets not return to userland just yet. It's constly and
+	 * it's likely we have more R2 instructions to emulate
+	 */
+	if (!err && (pass++ < MIPS_R2_EMUL_TOTAL_PASS)) {
+		regs->cp0_cause &= ~CAUSEF_BD;
+		err = get_user(inst, (u32 __user *)regs->cp0_epc);
+		if (!err)
+			goto repeat;
+
+		if (err < 0)
+			err = SIGSEGV;
+	}
+
+	if (err && (err != SIGEMT)) {
+		regs->regs[31] = r31;
+		regs->cp0_epc = epc;
+	}
+
+	/* Likely a MIPS R6 compatible instruction */
+	if (pass && (err == SIGILL))
+		err = 0;
+
+	return err;
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+static int mipsr2_stats_show(struct seq_file *s, void *unused)
+{
+
+	seq_printf(s, "Instruction\tTotal\tBDslot\n------------------------------\n");
+	seq_printf(s, "movs\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.movs),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.movs));
+	seq_printf(s, "hilo\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.hilo),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.hilo));
+	seq_printf(s, "muls\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.muls),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.muls));
+	seq_printf(s, "divs\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.divs),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.divs));
+	seq_printf(s, "dsps\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.dsps),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.dsps));
+	seq_printf(s, "bops\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.bops),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.bops));
+	seq_printf(s, "traps\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.traps),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.traps));
+	seq_printf(s, "fpus\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.fpus),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.fpus));
+	seq_printf(s, "loads\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.loads),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.loads));
+	seq_printf(s, "stores\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.stores),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.stores));
+	seq_printf(s, "llsc\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.llsc),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.llsc));
+	seq_printf(s, "dsemul\t\t%ld\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2emustats.dsemul),
+		   (unsigned long)__this_cpu_read(mipsr2bdemustats.dsemul));
+	seq_printf(s, "jr\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.jrs));
+	seq_printf(s, "bltzl\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.bltzl));
+	seq_printf(s, "bgezl\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.bgezl));
+	seq_printf(s, "bltzll\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.bltzll));
+	seq_printf(s, "bgezll\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.bgezll));
+	seq_printf(s, "bltzal\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.bltzal));
+	seq_printf(s, "bgezal\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.bgezal));
+	seq_printf(s, "beql\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.beql));
+	seq_printf(s, "bnel\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.bnel));
+	seq_printf(s, "blezl\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.blezl));
+	seq_printf(s, "bgtzl\t\t%ld\n",
+		   (unsigned long)__this_cpu_read(mipsr2bremustats.bgtzl));
+
+	return 0;
+}
+
+static int mipsr2_stats_clear_show(struct seq_file *s, void *unused)
+{
+	mipsr2_stats_show(s, unused);
+
+	__this_cpu_write((mipsr2emustats).movs, 0);
+	__this_cpu_write((mipsr2bdemustats).movs, 0);
+	__this_cpu_write((mipsr2emustats).hilo, 0);
+	__this_cpu_write((mipsr2bdemustats).hilo, 0);
+	__this_cpu_write((mipsr2emustats).muls, 0);
+	__this_cpu_write((mipsr2bdemustats).muls, 0);
+	__this_cpu_write((mipsr2emustats).divs, 0);
+	__this_cpu_write((mipsr2bdemustats).divs, 0);
+	__this_cpu_write((mipsr2emustats).dsps, 0);
+	__this_cpu_write((mipsr2bdemustats).dsps, 0);
+	__this_cpu_write((mipsr2emustats).bops, 0);
+	__this_cpu_write((mipsr2bdemustats).bops, 0);
+	__this_cpu_write((mipsr2emustats).traps, 0);
+	__this_cpu_write((mipsr2bdemustats).traps, 0);
+	__this_cpu_write((mipsr2emustats).fpus, 0);
+	__this_cpu_write((mipsr2bdemustats).fpus, 0);
+	__this_cpu_write((mipsr2emustats).loads, 0);
+	__this_cpu_write((mipsr2bdemustats).loads, 0);
+	__this_cpu_write((mipsr2emustats).stores, 0);
+	__this_cpu_write((mipsr2bdemustats).stores, 0);
+	__this_cpu_write((mipsr2emustats).llsc, 0);
+	__this_cpu_write((mipsr2bdemustats).llsc, 0);
+	__this_cpu_write((mipsr2emustats).dsemul, 0);
+	__this_cpu_write((mipsr2bdemustats).dsemul, 0);
+	__this_cpu_write((mipsr2bremustats).jrs, 0);
+	__this_cpu_write((mipsr2bremustats).bltzl, 0);
+	__this_cpu_write((mipsr2bremustats).bgezl, 0);
+	__this_cpu_write((mipsr2bremustats).bltzll, 0);
+	__this_cpu_write((mipsr2bremustats).bgezll, 0);
+	__this_cpu_write((mipsr2bremustats).bltzal, 0);
+	__this_cpu_write((mipsr2bremustats).bgezal, 0);
+	__this_cpu_write((mipsr2bremustats).beql, 0);
+	__this_cpu_write((mipsr2bremustats).bnel, 0);
+	__this_cpu_write((mipsr2bremustats).blezl, 0);
+	__this_cpu_write((mipsr2bremustats).bgtzl, 0);
+
+	return 0;
+}
+
+static int mipsr2_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, mipsr2_stats_show, inode->i_private);
+}
+
+static int mipsr2_stats_clear_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, mipsr2_stats_clear_show, inode->i_private);
+}
+
+static const struct file_operations mipsr2_emul_fops = {
+	.open                   = mipsr2_stats_open,
+	.read			= seq_read,
+	.llseek			= seq_lseek,
+	.release		= single_release,
+};
+
+static const struct file_operations mipsr2_clear_fops = {
+	.open                   = mipsr2_stats_clear_open,
+	.read			= seq_read,
+	.llseek			= seq_lseek,
+	.release		= single_release,
+};
+
+
+static int __init mipsr2_init_debugfs(void)
+{
+	extern struct dentry	*mips_debugfs_dir;
+	struct dentry		*mipsr2_emul;
+
+	if (!mips_debugfs_dir)
+		return -ENODEV;
+
+	mipsr2_emul = debugfs_create_file("r2_emul_stats", S_IRUGO,
+					  mips_debugfs_dir, NULL,
+					  &mipsr2_emul_fops);
+	if (!mipsr2_emul)
+		return -ENOMEM;
+
+	mipsr2_emul = debugfs_create_file("r2_emul_stats_clear", S_IRUGO,
+					  mips_debugfs_dir, NULL,
+					  &mipsr2_clear_fops);
+	if (!mipsr2_emul)
+		return -ENOMEM;
+
+	return 0;
+}
+
+device_initcall(mipsr2_init_debugfs);
+
+#endif /* CONFIG_DEBUG_FS */