powerpc: Emulate load/store floating double pair instructions

This adds lfdp[x] and stfdp[x] to the set of instructions that
analyse_instr() and emulate_step() understand.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/lib/sstep.c

@@ -415,9 +415,9 @@ static int do_fp_load(int rn, unsigned long ea, int nb, struct pt_regs *regs)
 	int err;
 	union {
 		float f;
-		double d;
-		unsigned long l;
-		u8 b[sizeof(double)];
+		double d[2];
+		unsigned long l[2];
+		u8 b[2 * sizeof(double)];
 	} u;
 
 	if (!address_ok(regs, ea, nb))
@@ -427,11 +427,19 @@ static int do_fp_load(int rn, unsigned long ea, int nb, struct pt_regs *regs)
 		return err;
 	preempt_disable();
 	if (nb == 4)
-		conv_sp_to_dp(&u.f, &u.d);
+		conv_sp_to_dp(&u.f, &u.d[0]);
 	if (regs->msr & MSR_FP)
-		put_fpr(rn, &u.d);
+		put_fpr(rn, &u.d[0]);
 	else
-		current->thread.TS_FPR(rn) = u.l;
+		current->thread.TS_FPR(rn) = u.l[0];
+	if (nb == 16) {
+		/* lfdp */
+		rn |= 1;
+		if (regs->msr & MSR_FP)
+			put_fpr(rn, &u.d[1]);
+		else
+			current->thread.TS_FPR(rn) = u.l[1];
+	}
 	preempt_enable();
 	return 0;
 }
@@ -441,20 +449,27 @@ static int do_fp_store(int rn, unsigned long ea, int nb, struct pt_regs *regs)
 {
 	union {
 		float f;
-		double d;
-		unsigned long l;
-		u8 b[sizeof(double)];
+		double d[2];
+		unsigned long l[2];
+		u8 b[2 * sizeof(double)];
 	} u;
 
 	if (!address_ok(regs, ea, nb))
 		return -EFAULT;
 	preempt_disable();
 	if (regs->msr & MSR_FP)
-		get_fpr(rn, &u.d);
+		get_fpr(rn, &u.d[0]);
 	else
-		u.l = current->thread.TS_FPR(rn);
+		u.l[0] = current->thread.TS_FPR(rn);
 	if (nb == 4)
-		conv_dp_to_sp(&u.d, &u.f);
+		conv_dp_to_sp(&u.d[0], &u.f);
+	if (nb == 16) {
+		rn |= 1;
+		if (regs->msr & MSR_FP)
+			get_fpr(rn, &u.d[1]);
+		else
+			u.l[1] = current->thread.TS_FPR(rn);
+	}
 	preempt_enable();
 	return copy_mem_out(u.b, ea, nb);
 }
@@ -1938,7 +1953,17 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 		case 759:	/* stfdux */
 			op->type = MKOP(STORE_FP, u, 8);
 			break;
-#endif
+
+#ifdef __powerpc64__
+		case 791:	/* lfdpx */
+			op->type = MKOP(LOAD_FP, 0, 16);
+			break;
+
+		case 919:	/* stfdpx */
+			op->type = MKOP(STORE_FP, 0, 16);
+			break;
+#endif /* __powerpc64 */
+#endif /* CONFIG_PPC_FPU */
 
 #ifdef __powerpc64__
 		case 660:	/* stdbrx */
@@ -1956,7 +1981,7 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 			op->val = byterev_4(regs->gpr[rd]);
 			break;
 
-		case 725:
+		case 725:	/* stswi */
 			if (rb == 0)
 				rb = 32;	/* # bytes to store */
 			op->type = MKOP(STORE_MULTI, 0, rb);
@@ -2246,9 +2271,14 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 #endif
 
 #ifdef CONFIG_VSX
-	case 57:	/* lxsd, lxssp */
+	case 57:	/* lfdp, lxsd, lxssp */
 		op->ea = dsform_ea(instr, regs);
 		switch (instr & 3) {
+		case 0:		/* lfdp */
+			if (rd & 1)
+				break;		/* reg must be even */
+			op->type = MKOP(LOAD_FP, 0, 16);
+			break;
 		case 2:		/* lxsd */
 			op->reg = rd + 32;
 			op->type = MKOP(LOAD_VSX, 0, 8);
@@ -2283,8 +2313,14 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 #endif
 
 #ifdef CONFIG_VSX
-	case 61:	/* lxv, stxsd, stxssp, stxv */
+	case 61:	/* stfdp, lxv, stxsd, stxssp, stxv */
 		switch (instr & 7) {
+		case 0:		/* stfdp with LSB of DS field = 0 */
+		case 4:		/* stfdp with LSB of DS field = 1 */
+			op->ea = dsform_ea(instr, regs);
+			op->type = MKOP(STORE_FP, 0, 16);
+			break;
+
 		case 1:		/* lxv */
 			op->ea = dqform_ea(instr, regs);
 			if (instr & 8)