[ARM] 3749/3: Correct VFP single/double conversion emulation

Patch from Daniel Jacobowitz

The fcvtsd/fcvtds emulation was left behind when the numbering of double
precision registers was changed from 0-30 to 0-15.  Both conversion
instructions were writing their results to the wrong register.  Also,
the conversion instructions should stop after the first element even
if a vector length is specified.
Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/vfp/vfpdouble.c

@@ -1127,7 +1127,7 @@ u32 vfp_double_cpdo(u32 inst, u32 fpscr)
 {
 	u32 op = inst & FOP_MASK;
 	u32 exceptions = 0;
-	unsigned int dd = vfp_get_dd(inst);
+	unsigned int dest;
 	unsigned int dn = vfp_get_dn(inst);
 	unsigned int dm = vfp_get_dm(inst);
 	unsigned int vecitr, veclen, vecstride;
@@ -1136,11 +1136,21 @@ u32 vfp_double_cpdo(u32 inst, u32 fpscr)
 	veclen = fpscr & FPSCR_LENGTH_MASK;
 	vecstride = (1 + ((fpscr & FPSCR_STRIDE_MASK) == FPSCR_STRIDE_MASK)) * 2;
 
+	/*
+	 * fcvtds takes an sN register number as destination, not dN.
+	 * It also always operates on scalars.
+	 */
+	if ((inst & FEXT_MASK) == FEXT_FCVT) {
+		veclen = 0;
+		dest = vfp_get_sd(inst);
+	} else
+		dest = vfp_get_dd(inst);
+
 	/*
 	 * If destination bank is zero, vector length is always '1'.
 	 * ARM DDI0100F C5.1.3, C5.3.2.
 	 */
-	if (FREG_BANK(dd) == 0)
+	if (FREG_BANK(dest) == 0)
 		veclen = 0;
 
 	pr_debug("VFP: vecstride=%u veclen=%u\n", vecstride,
@@ -1153,16 +1163,20 @@ u32 vfp_double_cpdo(u32 inst, u32 fpscr)
 	for (vecitr = 0; vecitr <= veclen; vecitr += 1 << FPSCR_LENGTH_BIT) {
 		u32 except;
 
-		if (op == FOP_EXT)
+		if (op == FOP_EXT && (inst & FEXT_MASK) == FEXT_FCVT)
+			pr_debug("VFP: itr%d (s%u) = op[%u] (d%u)\n",
+				 vecitr >> FPSCR_LENGTH_BIT,
+				 dest, dn, dm);
+		else if (op == FOP_EXT)
 			pr_debug("VFP: itr%d (d%u) = op[%u] (d%u)\n",
 				 vecitr >> FPSCR_LENGTH_BIT,
-				 dd, dn, dm);
+				 dest, dn, dm);
 		else
 			pr_debug("VFP: itr%d (d%u) = (d%u) op[%u] (d%u)\n",
 				 vecitr >> FPSCR_LENGTH_BIT,
-				 dd, dn, FOP_TO_IDX(op), dm);
+				 dest, dn, FOP_TO_IDX(op), dm);
 
-		except = fop(dd, dn, dm, fpscr);
+		except = fop(dest, dn, dm, fpscr);
 		pr_debug("VFP: itr%d: exceptions=%08x\n",
 			 vecitr >> FPSCR_LENGTH_BIT, except);
 
@@ -1180,7 +1194,7 @@ u32 vfp_double_cpdo(u32 inst, u32 fpscr)
 		 * we encounter an exception.  We continue.
 		 */
 
-		dd = FREG_BANK(dd) + ((FREG_IDX(dd) + vecstride) & 6);
+		dest = FREG_BANK(dest) + ((FREG_IDX(dest) + vecstride) & 6);
 		dn = FREG_BANK(dn) + ((FREG_IDX(dn) + vecstride) & 6);
 		if (FREG_BANK(dm) != 0)
 			dm = FREG_BANK(dm) + ((FREG_IDX(dm) + vecstride) & 6);

arch/arm/vfp/vfpsingle.c

@@ -514,10 +514,6 @@ static u32 vfp_single_fcvtd(int dd, int unused, s32 m, u32 fpscr)
 	else
 		vdd.exponent = vsm.exponent + (1023 - 127);
 
-	/*
-	 * Technically, if bit 0 of dd is set, this is an invalid
-	 * instruction.  However, we ignore this for efficiency.
-	 */
 	return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fcvtd");
 
  pack_nan:
@@ -1174,7 +1170,7 @@ u32 vfp_single_cpdo(u32 inst, u32 fpscr)
 {
 	u32 op = inst & FOP_MASK;
 	u32 exceptions = 0;
-	unsigned int sd = vfp_get_sd(inst);
+	unsigned int dest;
 	unsigned int sn = vfp_get_sn(inst);
 	unsigned int sm = vfp_get_sm(inst);
 	unsigned int vecitr, veclen, vecstride;
@@ -1183,11 +1179,23 @@ u32 vfp_single_cpdo(u32 inst, u32 fpscr)
 	veclen = fpscr & FPSCR_LENGTH_MASK;
 	vecstride = 1 + ((fpscr & FPSCR_STRIDE_MASK) == FPSCR_STRIDE_MASK);
 
+	/*
+	 * fcvtsd takes a dN register number as destination, not sN.
+	 * Technically, if bit 0 of dd is set, this is an invalid
+	 * instruction.  However, we ignore this for efficiency.
+	 * It also only operates on scalars.
+	 */
+	if ((inst & FEXT_MASK) == FEXT_FCVT) {
+		veclen = 0;
+		dest = vfp_get_dd(inst);
+	} else
+		dest = vfp_get_sd(inst);
+
 	/*
 	 * If destination bank is zero, vector length is always '1'.
 	 * ARM DDI0100F C5.1.3, C5.3.2.
 	 */
-	if (FREG_BANK(sd) == 0)
+	if (FREG_BANK(dest) == 0)
 		veclen = 0;
 
 	pr_debug("VFP: vecstride=%u veclen=%u\n", vecstride,
@@ -1201,15 +1209,18 @@ u32 vfp_single_cpdo(u32 inst, u32 fpscr)
 		s32 m = vfp_get_float(sm);
 		u32 except;
 
-		if (op == FOP_EXT)
+		if (op == FOP_EXT && (inst & FEXT_MASK) == FEXT_FCVT)
+			pr_debug("VFP: itr%d (d%u) = op[%u] (s%u=%08x)\n",
+				 vecitr >> FPSCR_LENGTH_BIT, dest, sn, sm, m);
+		else if (op == FOP_EXT)
 			pr_debug("VFP: itr%d (s%u) = op[%u] (s%u=%08x)\n",
-				 vecitr >> FPSCR_LENGTH_BIT, sd, sn, sm, m);
+				 vecitr >> FPSCR_LENGTH_BIT, dest, sn, sm, m);
 		else
 			pr_debug("VFP: itr%d (s%u) = (s%u) op[%u] (s%u=%08x)\n",
-				 vecitr >> FPSCR_LENGTH_BIT, sd, sn,
+				 vecitr >> FPSCR_LENGTH_BIT, dest, sn,
 				 FOP_TO_IDX(op), sm, m);
 
-		except = fop(sd, sn, m, fpscr);
+		except = fop(dest, sn, m, fpscr);
 		pr_debug("VFP: itr%d: exceptions=%08x\n",
 			 vecitr >> FPSCR_LENGTH_BIT, except);
 
@@ -1227,7 +1238,7 @@ u32 vfp_single_cpdo(u32 inst, u32 fpscr)
 		 * we encounter an exception.  We continue.
 		 */
 
-		sd = FREG_BANK(sd) + ((FREG_IDX(sd) + vecstride) & 7);
+		dest = FREG_BANK(dest) + ((FREG_IDX(dest) + vecstride) & 7);
 		sn = FREG_BANK(sn) + ((FREG_IDX(sn) + vecstride) & 7);
 		if (FREG_BANK(sm) != 0)
 			sm = FREG_BANK(sm) + ((FREG_IDX(sm) + vecstride) & 7);