Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 525 insertions, 0 deletions

diff --git a/arch/sparc/math-emu/math_64.c b/arch/sparc/math-emu/math_64.c
new file mode 100644
index 000000000..1379dee26
--- /dev/null
+++ b/arch/sparc/math-emu/math_64.c
@@ -0,0 +1,525 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * arch/sparc64/math-emu/math.c
+ *
+ * Copyright (C) 1997,1999 Jakub Jelinek (jj@ultra.linux.cz)
+ * Copyright (C) 1999 David S. Miller (davem@redhat.com)
+ *
+ * Emulation routines originate from soft-fp package, which is part
+ * of glibc and has appropriate copyrights in it.
+ */
+
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/perf_event.h>
+
+#include <asm/fpumacro.h>
+#include <asm/ptrace.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+#include "sfp-util_64.h"
+#include <math-emu/soft-fp.h>
+#include <math-emu/single.h>
+#include <math-emu/double.h>
+#include <math-emu/quad.h>
+
+/* QUAD - ftt == 3 */
+#define FMOVQ	0x003
+#define FNEGQ	0x007
+#define FABSQ	0x00b
+#define FSQRTQ	0x02b
+#define FADDQ	0x043
+#define FSUBQ	0x047
+#define FMULQ	0x04b
+#define FDIVQ	0x04f
+#define FDMULQ	0x06e
+#define FQTOX	0x083
+#define FXTOQ	0x08c
+#define FQTOS	0x0c7
+#define FQTOD	0x0cb
+#define FITOQ	0x0cc
+#define FSTOQ	0x0cd
+#define FDTOQ	0x0ce
+#define FQTOI	0x0d3
+/* SUBNORMAL - ftt == 2 */
+#define FSQRTS	0x029
+#define FSQRTD	0x02a
+#define FADDS	0x041
+#define FADDD	0x042
+#define FSUBS	0x045
+#define FSUBD	0x046
+#define FMULS	0x049
+#define FMULD	0x04a
+#define FDIVS	0x04d
+#define FDIVD	0x04e
+#define FSMULD	0x069
+#define FSTOX	0x081
+#define FDTOX	0x082
+#define FDTOS	0x0c6
+#define FSTOD	0x0c9
+#define FSTOI	0x0d1
+#define FDTOI	0x0d2
+#define FXTOS	0x084 /* Only Ultra-III generates this. */
+#define FXTOD	0x088 /* Only Ultra-III generates this. */
+#if 0	/* Optimized inline in sparc64/kernel/entry.S */
+#define FITOS	0x0c4 /* Only Ultra-III generates this. */
+#endif
+#define FITOD	0x0c8 /* Only Ultra-III generates this. */
+/* FPOP2 */
+#define FCMPQ	0x053
+#define FCMPEQ	0x057
+#define FMOVQ0	0x003
+#define FMOVQ1	0x043
+#define FMOVQ2	0x083
+#define FMOVQ3	0x0c3
+#define FMOVQI	0x103
+#define FMOVQX	0x183
+#define FMOVQZ	0x027
+#define FMOVQLE	0x047
+#define FMOVQLZ 0x067
+#define FMOVQNZ	0x0a7
+#define FMOVQGZ	0x0c7
+#define FMOVQGE 0x0e7
+
+#define FSR_TEM_SHIFT	23UL
+#define FSR_TEM_MASK	(0x1fUL << FSR_TEM_SHIFT)
+#define FSR_AEXC_SHIFT	5UL
+#define FSR_AEXC_MASK	(0x1fUL << FSR_AEXC_SHIFT)
+#define FSR_CEXC_SHIFT	0UL
+#define FSR_CEXC_MASK	(0x1fUL << FSR_CEXC_SHIFT)
+
+/* All routines returning an exception to raise should detect
+ * such exceptions _before_ rounding to be consistent with
+ * the behavior of the hardware in the implemented cases
+ * (and thus with the recommendations in the V9 architecture
+ * manual).
+ *
+ * We return 0 if a SIGFPE should be sent, 1 otherwise.
+ */
+static inline int record_exception(struct pt_regs *regs, int eflag)
+{
+	u64 fsr = current_thread_info()->xfsr[0];
+	int would_trap;
+
+	/* Determine if this exception would have generated a trap. */
+	would_trap = (fsr & ((long)eflag << FSR_TEM_SHIFT)) != 0UL;
+
+	/* If trapping, we only want to signal one bit. */
+	if(would_trap != 0) {
+		eflag &= ((fsr & FSR_TEM_MASK) >> FSR_TEM_SHIFT);
+		if((eflag & (eflag - 1)) != 0) {
+			if(eflag & FP_EX_INVALID)
+				eflag = FP_EX_INVALID;
+			else if(eflag & FP_EX_OVERFLOW)
+				eflag = FP_EX_OVERFLOW;
+			else if(eflag & FP_EX_UNDERFLOW)
+				eflag = FP_EX_UNDERFLOW;
+			else if(eflag & FP_EX_DIVZERO)
+				eflag = FP_EX_DIVZERO;
+			else if(eflag & FP_EX_INEXACT)
+				eflag = FP_EX_INEXACT;
+		}
+	}
+
+	/* Set CEXC, here is the rule:
+	 *
+	 *    In general all FPU ops will set one and only one
+	 *    bit in the CEXC field, this is always the case
+	 *    when the IEEE exception trap is enabled in TEM.
+	 */
+	fsr &= ~(FSR_CEXC_MASK);
+	fsr |= ((long)eflag << FSR_CEXC_SHIFT);
+
+	/* Set the AEXC field, rule is:
+	 *
+	 *    If a trap would not be generated, the
+	 *    CEXC just generated is OR'd into the
+	 *    existing value of AEXC.
+	 */
+	if(would_trap == 0)
+		fsr |= ((long)eflag << FSR_AEXC_SHIFT);
+
+	/* If trapping, indicate fault trap type IEEE. */
+	if(would_trap != 0)
+		fsr |= (1UL << 14);
+
+	current_thread_info()->xfsr[0] = fsr;
+
+	/* If we will not trap, advance the program counter over
+	 * the instruction being handled.
+	 */
+	if(would_trap == 0) {
+		regs->tpc = regs->tnpc;
+		regs->tnpc += 4;
+	}
+
+	return (would_trap ? 0 : 1);
+}
+
+typedef union {
+	u32 s;
+	u64 d;
+	u64 q[2];
+} *argp;
+
+int do_mathemu(struct pt_regs *regs, struct fpustate *f, bool illegal_insn_trap)
+{
+	unsigned long pc = regs->tpc;
+	unsigned long tstate = regs->tstate;
+	u32 insn = 0;
+	int type = 0;
+	/* ftt tells which ftt it may happen in, r is rd, b is rs2 and a is rs1. The *u arg tells
+	   whether the argument should be packed/unpacked (0 - do not unpack/pack, 1 - unpack/pack)
+	   non-u args tells the size of the argument (0 - no argument, 1 - single, 2 - double, 3 - quad */
+#define TYPE(ftt, r, ru, b, bu, a, au) type = (au << 2) | (a << 0) | (bu << 5) | (b << 3) | (ru << 8) | (r << 6) | (ftt << 9)
+	int freg;
+	static u64 zero[2] = { 0L, 0L };
+	int flags;
+	FP_DECL_EX;
+	FP_DECL_S(SA); FP_DECL_S(SB); FP_DECL_S(SR);
+	FP_DECL_D(DA); FP_DECL_D(DB); FP_DECL_D(DR);
+	FP_DECL_Q(QA); FP_DECL_Q(QB); FP_DECL_Q(QR);
+	int IR;
+	long XR, xfsr;
+
+	if (tstate & TSTATE_PRIV)
+		die_if_kernel("unfinished/unimplemented FPop from kernel", regs);
+	perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, 0);
+	if (test_thread_flag(TIF_32BIT))
+		pc = (u32)pc;
+	if (get_user(insn, (u32 __user *) pc) != -EFAULT) {
+		if ((insn & 0xc1f80000) == 0x81a00000) /* FPOP1 */ {
+			switch ((insn >> 5) & 0x1ff) {
+			/* QUAD - ftt == 3 */
+			case FMOVQ:
+			case FNEGQ:
+			case FABSQ: TYPE(3,3,0,3,0,0,0); break;
+			case FSQRTQ: TYPE(3,3,1,3,1,0,0); break;
+			case FADDQ:
+			case FSUBQ:
+			case FMULQ:
+			case FDIVQ: TYPE(3,3,1,3,1,3,1); break;
+			case FDMULQ: TYPE(3,3,1,2,1,2,1); break;
+			case FQTOX: TYPE(3,2,0,3,1,0,0); break;
+			case FXTOQ: TYPE(3,3,1,2,0,0,0); break;
+			case FQTOS: TYPE(3,1,1,3,1,0,0); break;
+			case FQTOD: TYPE(3,2,1,3,1,0,0); break;
+			case FITOQ: TYPE(3,3,1,1,0,0,0); break;
+			case FSTOQ: TYPE(3,3,1,1,1,0,0); break;
+			case FDTOQ: TYPE(3,3,1,2,1,0,0); break;
+			case FQTOI: TYPE(3,1,0,3,1,0,0); break;
+
+			/* We can get either unimplemented or unfinished
+			 * for these cases.  Pre-Niagara systems generate
+			 * unfinished fpop for SUBNORMAL cases, and Niagara
+			 * always gives unimplemented fpop for fsqrt{s,d}.
+			 */
+			case FSQRTS: {
+				unsigned long x = current_thread_info()->xfsr[0];
+
+				x = (x >> 14) & 0x7;
+				TYPE(x,1,1,1,1,0,0);
+				break;
+			}
+
+			case FSQRTD: {
+				unsigned long x = current_thread_info()->xfsr[0];
+
+				x = (x >> 14) & 0x7;
+				TYPE(x,2,1,2,1,0,0);
+				break;
+			}
+
+			/* SUBNORMAL - ftt == 2 */
+			case FADDD:
+			case FSUBD:
+			case FMULD:
+			case FDIVD: TYPE(2,2,1,2,1,2,1); break;
+			case FADDS:
+			case FSUBS:
+			case FMULS:
+			case FDIVS: TYPE(2,1,1,1,1,1,1); break;
+			case FSMULD: TYPE(2,2,1,1,1,1,1); break;
+			case FSTOX: TYPE(2,2,0,1,1,0,0); break;
+			case FDTOX: TYPE(2,2,0,2,1,0,0); break;
+			case FDTOS: TYPE(2,1,1,2,1,0,0); break;
+			case FSTOD: TYPE(2,2,1,1,1,0,0); break;
+			case FSTOI: TYPE(2,1,0,1,1,0,0); break;
+			case FDTOI: TYPE(2,1,0,2,1,0,0); break;
+
+			/* Only Ultra-III generates these */
+			case FXTOS: TYPE(2,1,1,2,0,0,0); break;
+			case FXTOD: TYPE(2,2,1,2,0,0,0); break;
+#if 0			/* Optimized inline in sparc64/kernel/entry.S */
+			case FITOS: TYPE(2,1,1,1,0,0,0); break;
+#endif
+			case FITOD: TYPE(2,2,1,1,0,0,0); break;
+			}
+		}
+		else if ((insn & 0xc1f80000) == 0x81a80000) /* FPOP2 */ {
+			IR = 2;
+			switch ((insn >> 5) & 0x1ff) {
+			case FCMPQ: TYPE(3,0,0,3,1,3,1); break;
+			case FCMPEQ: TYPE(3,0,0,3,1,3,1); break;
+			/* Now the conditional fmovq support */
+			case FMOVQ0:
+			case FMOVQ1:
+			case FMOVQ2:
+			case FMOVQ3:
+				/* fmovq %fccX, %fY, %fZ */
+				if (!((insn >> 11) & 3))
+					XR = current_thread_info()->xfsr[0] >> 10;
+				else
+					XR = current_thread_info()->xfsr[0] >> (30 + ((insn >> 10) & 0x6));
+				XR &= 3;
+				IR = 0;
+				switch ((insn >> 14) & 0x7) {
+				/* case 0: IR = 0; break; */			/* Never */
+				case 1: if (XR) IR = 1; break;			/* Not Equal */
+				case 2: if (XR == 1 || XR == 2) IR = 1; break;	/* Less or Greater */
+				case 3: if (XR & 1) IR = 1; break;		/* Unordered or Less */
+				case 4: if (XR == 1) IR = 1; break;		/* Less */
+				case 5: if (XR & 2) IR = 1; break;		/* Unordered or Greater */
+				case 6: if (XR == 2) IR = 1; break;		/* Greater */
+				case 7: if (XR == 3) IR = 1; break;		/* Unordered */
+				}
+				if ((insn >> 14) & 8)
+					IR ^= 1;
+				break;
+			case FMOVQI:
+			case FMOVQX:
+				/* fmovq %[ix]cc, %fY, %fZ */
+				XR = regs->tstate >> 32;
+				if ((insn >> 5) & 0x80)
+					XR >>= 4;
+				XR &= 0xf;
+				IR = 0;
+				freg = ((XR >> 2) ^ XR) & 2;
+				switch ((insn >> 14) & 0x7) {
+				/* case 0: IR = 0; break; */			/* Never */
+				case 1: if (XR & 4) IR = 1; break;		/* Equal */
+				case 2: if ((XR & 4) || freg) IR = 1; break;	/* Less or Equal */
+				case 3: if (freg) IR = 1; break;		/* Less */
+				case 4: if (XR & 5) IR = 1; break;		/* Less or Equal Unsigned */
+				case 5: if (XR & 1) IR = 1; break;		/* Carry Set */
+				case 6: if (XR & 8) IR = 1; break;		/* Negative */
+				case 7: if (XR & 2) IR = 1; break;		/* Overflow Set */
+				}
+				if ((insn >> 14) & 8)
+					IR ^= 1;
+				break;
+			case FMOVQZ:
+			case FMOVQLE:
+			case FMOVQLZ:
+			case FMOVQNZ:
+			case FMOVQGZ:
+			case FMOVQGE:
+				freg = (insn >> 14) & 0x1f;
+				if (!freg)
+					XR = 0;
+				else if (freg < 16)
+					XR = regs->u_regs[freg];
+				else if (!test_thread_64bit_stack(regs->u_regs[UREG_FP])) {
+					struct reg_window32 __user *win32;
+					flushw_user ();
+					win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
+					get_user(XR, &win32->locals[freg - 16]);
+				} else {
+					struct reg_window __user *win;
+					flushw_user ();
+					win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+					get_user(XR, &win->locals[freg - 16]);
+				}
+				IR = 0;
+				switch ((insn >> 10) & 3) {
+				case 1: if (!XR) IR = 1; break;			/* Register Zero */
+				case 2: if (XR <= 0) IR = 1; break;		/* Register Less Than or Equal to Zero */
+				case 3: if (XR < 0) IR = 1; break;		/* Register Less Than Zero */
+				}
+				if ((insn >> 10) & 4)
+					IR ^= 1;
+				break;
+			}
+			if (IR == 0) {
+				/* The fmov test was false. Do a nop instead */
+				current_thread_info()->xfsr[0] &= ~(FSR_CEXC_MASK);
+				regs->tpc = regs->tnpc;
+				regs->tnpc += 4;
+				return 1;
+			} else if (IR == 1) {
+				/* Change the instruction into plain fmovq */
+				insn = (insn & 0x3e00001f) | 0x81a00060;
+				TYPE(3,3,0,3,0,0,0); 
+			}
+		}
+	}
+	if (type) {
+		argp rs1 = NULL, rs2 = NULL, rd = NULL;
+		
+		/* Starting with UltraSPARC-T2, the cpu does not set the FP Trap
+		 * Type field in the %fsr to unimplemented_FPop.  Nor does it
+		 * use the fp_exception_other trap.  Instead it signals an
+		 * illegal instruction and leaves the FP trap type field of
+		 * the %fsr unchanged.
+		 */
+		if (!illegal_insn_trap) {
+			int ftt = (current_thread_info()->xfsr[0] >> 14) & 0x7;
+			if (ftt != (type >> 9))
+				goto err;
+		}
+		current_thread_info()->xfsr[0] &= ~0x1c000;
+		freg = ((insn >> 14) & 0x1f);
+		switch (type & 0x3) {
+		case 3: if (freg & 2) {
+				current_thread_info()->xfsr[0] |= (6 << 14) /* invalid_fp_register */;
+				goto err;
+			}
+		case 2: freg = ((freg & 1) << 5) | (freg & 0x1e);
+		case 1: rs1 = (argp)&f->regs[freg];
+			flags = (freg < 32) ? FPRS_DL : FPRS_DU; 
+			if (!(current_thread_info()->fpsaved[0] & flags))
+				rs1 = (argp)&zero;
+			break;
+		}
+		switch (type & 0x7) {
+		case 7: FP_UNPACK_QP (QA, rs1); break;
+		case 6: FP_UNPACK_DP (DA, rs1); break;
+		case 5: FP_UNPACK_SP (SA, rs1); break;
+		}
+		freg = (insn & 0x1f);
+		switch ((type >> 3) & 0x3) {
+		case 3: if (freg & 2) {
+				current_thread_info()->xfsr[0] |= (6 << 14) /* invalid_fp_register */;
+				goto err;
+			}
+		case 2: freg = ((freg & 1) << 5) | (freg & 0x1e);
+		case 1: rs2 = (argp)&f->regs[freg];
+			flags = (freg < 32) ? FPRS_DL : FPRS_DU; 
+			if (!(current_thread_info()->fpsaved[0] & flags))
+				rs2 = (argp)&zero;
+			break;
+		}
+		switch ((type >> 3) & 0x7) {
+		case 7: FP_UNPACK_QP (QB, rs2); break;
+		case 6: FP_UNPACK_DP (DB, rs2); break;
+		case 5: FP_UNPACK_SP (SB, rs2); break;
+		}
+		freg = ((insn >> 25) & 0x1f);
+		switch ((type >> 6) & 0x3) {
+		case 3: if (freg & 2) {
+				current_thread_info()->xfsr[0] |= (6 << 14) /* invalid_fp_register */;
+				goto err;
+			}
+		case 2: freg = ((freg & 1) << 5) | (freg & 0x1e);
+		case 1: rd = (argp)&f->regs[freg];
+			flags = (freg < 32) ? FPRS_DL : FPRS_DU; 
+			if (!(current_thread_info()->fpsaved[0] & FPRS_FEF)) {
+				current_thread_info()->fpsaved[0] = FPRS_FEF;
+				current_thread_info()->gsr[0] = 0;
+			}
+			if (!(current_thread_info()->fpsaved[0] & flags)) {
+				if (freg < 32)
+					memset(f->regs, 0, 32*sizeof(u32));
+				else
+					memset(f->regs+32, 0, 32*sizeof(u32));
+			}
+			current_thread_info()->fpsaved[0] |= flags;
+			break;
+		}
+		switch ((insn >> 5) & 0x1ff) {
+		/* + */
+		case FADDS: FP_ADD_S (SR, SA, SB); break;
+		case FADDD: FP_ADD_D (DR, DA, DB); break;
+		case FADDQ: FP_ADD_Q (QR, QA, QB); break;
+		/* - */
+		case FSUBS: FP_SUB_S (SR, SA, SB); break;
+		case FSUBD: FP_SUB_D (DR, DA, DB); break;
+		case FSUBQ: FP_SUB_Q (QR, QA, QB); break;
+		/* * */
+		case FMULS: FP_MUL_S (SR, SA, SB); break;
+		case FSMULD: FP_CONV (D, S, 1, 1, DA, SA);
+			     FP_CONV (D, S, 1, 1, DB, SB);
+		case FMULD: FP_MUL_D (DR, DA, DB); break;
+		case FDMULQ: FP_CONV (Q, D, 2, 1, QA, DA);
+			     FP_CONV (Q, D, 2, 1, QB, DB);
+		case FMULQ: FP_MUL_Q (QR, QA, QB); break;
+		/* / */
+		case FDIVS: FP_DIV_S (SR, SA, SB); break;
+		case FDIVD: FP_DIV_D (DR, DA, DB); break;
+		case FDIVQ: FP_DIV_Q (QR, QA, QB); break;
+		/* sqrt */
+		case FSQRTS: FP_SQRT_S (SR, SB); break;
+		case FSQRTD: FP_SQRT_D (DR, DB); break;
+		case FSQRTQ: FP_SQRT_Q (QR, QB); break;
+		/* mov */
+		case FMOVQ: rd->q[0] = rs2->q[0]; rd->q[1] = rs2->q[1]; break;
+		case FABSQ: rd->q[0] = rs2->q[0] & 0x7fffffffffffffffUL; rd->q[1] = rs2->q[1]; break;
+		case FNEGQ: rd->q[0] = rs2->q[0] ^ 0x8000000000000000UL; rd->q[1] = rs2->q[1]; break;
+		/* float to int */
+		case FSTOI: FP_TO_INT_S (IR, SB, 32, 1); break;
+		case FDTOI: FP_TO_INT_D (IR, DB, 32, 1); break;
+		case FQTOI: FP_TO_INT_Q (IR, QB, 32, 1); break;
+		case FSTOX: FP_TO_INT_S (XR, SB, 64, 1); break;
+		case FDTOX: FP_TO_INT_D (XR, DB, 64, 1); break;
+		case FQTOX: FP_TO_INT_Q (XR, QB, 64, 1); break;
+		/* int to float */
+		case FITOQ: IR = rs2->s; FP_FROM_INT_Q (QR, IR, 32, int); break;
+		case FXTOQ: XR = rs2->d; FP_FROM_INT_Q (QR, XR, 64, long); break;
+		/* Only Ultra-III generates these */
+		case FXTOS: XR = rs2->d; FP_FROM_INT_S (SR, XR, 64, long); break;
+		case FXTOD: XR = rs2->d; FP_FROM_INT_D (DR, XR, 64, long); break;
+#if 0		/* Optimized inline in sparc64/kernel/entry.S */
+		case FITOS: IR = rs2->s; FP_FROM_INT_S (SR, IR, 32, int); break;
+#endif
+		case FITOD: IR = rs2->s; FP_FROM_INT_D (DR, IR, 32, int); break;
+		/* float to float */
+		case FSTOD: FP_CONV (D, S, 1, 1, DR, SB); break;
+		case FSTOQ: FP_CONV (Q, S, 2, 1, QR, SB); break;
+		case FDTOQ: FP_CONV (Q, D, 2, 1, QR, DB); break;
+		case FDTOS: FP_CONV (S, D, 1, 1, SR, DB); break;
+		case FQTOS: FP_CONV (S, Q, 1, 2, SR, QB); break;
+		case FQTOD: FP_CONV (D, Q, 1, 2, DR, QB); break;
+		/* comparison */
+		case FCMPQ:
+		case FCMPEQ:
+			FP_CMP_Q(XR, QB, QA, 3);
+			if (XR == 3 &&
+			    (((insn >> 5) & 0x1ff) == FCMPEQ ||
+			     FP_ISSIGNAN_Q(QA) ||
+			     FP_ISSIGNAN_Q(QB)))
+				FP_SET_EXCEPTION (FP_EX_INVALID);
+		}
+		if (!FP_INHIBIT_RESULTS) {
+			switch ((type >> 6) & 0x7) {
+			case 0: xfsr = current_thread_info()->xfsr[0];
+				if (XR == -1) XR = 2;
+				switch (freg & 3) {
+				/* fcc0, 1, 2, 3 */
+				case 0: xfsr &= ~0xc00; xfsr |= (XR << 10); break;
+				case 1: xfsr &= ~0x300000000UL; xfsr |= (XR << 32); break;
+				case 2: xfsr &= ~0xc00000000UL; xfsr |= (XR << 34); break;
+				case 3: xfsr &= ~0x3000000000UL; xfsr |= (XR << 36); break;
+				}
+				current_thread_info()->xfsr[0] = xfsr;
+				break;
+			case 1: rd->s = IR; break;
+			case 2: rd->d = XR; break;
+			case 5: FP_PACK_SP (rd, SR); break;
+			case 6: FP_PACK_DP (rd, DR); break;
+			case 7: FP_PACK_QP (rd, QR); break;
+			}
+		}
+
+		if(_fex != 0)
+			return record_exception(regs, _fex);
+
+		/* Success and no exceptions detected. */
+		current_thread_info()->xfsr[0] &= ~(FSR_CEXC_MASK);
+		regs->tpc = regs->tnpc;
+		regs->tnpc += 4;
+		return 1;
+	}
+err:	return 0;
+}