powerpc/lib/sstep: Add prty instruction emulation

This adds emulation for the prtyw and prtyd instructions.
Tested for logical correctness against the prtyw and prtyd instructions
on ppc64le.
Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
Reviewed-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/lib/sstep.c

@@ -657,6 +657,24 @@ static nokprobe_inline void do_bpermd(struct pt_regs *regs, unsigned long v1,
 	regs->gpr[ra] = perm;
 }
 #endif /* CONFIG_PPC64 */
+/*
+ * The size parameter adjusts the equivalent prty instruction.
+ * prtyw = 32, prtyd = 64
+ */
+static nokprobe_inline void do_prty(struct pt_regs *regs, unsigned long v,
+				int size, int ra)
+{
+	unsigned long long res = v ^ (v >> 8);
+
+	res ^= res >> 16;
+	if (size == 32) {		/* prtyw */
+		regs->gpr[ra] = res & 0x0000000100000001;
+		return;
+	}
+
+	res ^= res >> 32;
+	regs->gpr[ra] = res & 1;	/*prtyd */
+}
 
 static nokprobe_inline int trap_compare(long v1, long v2)
 {
@@ -1262,6 +1280,14 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs,
 		case 124:	/* nor */
 			regs->gpr[ra] = ~(regs->gpr[rd] | regs->gpr[rb]);
 			goto logical_done;
+
+		case 154:	/* prtyw */
+			do_prty(regs, regs->gpr[rd], 32, ra);
+			goto logical_done;
+
+		case 186:	/* prtyd */
+			do_prty(regs, regs->gpr[rd], 64, ra);
+			goto logical_done;
 #ifdef CONFIG_PPC64
 		case 252:	/* bpermd */
 			do_bpermd(regs, regs->gpr[rd], regs->gpr[rb], ra);