powerpc/sstep: Introduce macros to retrieve Prefix instruction operands

retrieve prefix instruction operands RA and pc relative bit R values
using macros and adopt it in sstep.c and test_emulate_step.c.
Signed-off-by: Balamuruhan S <bala24@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200626095158.1031507-4-bala24@linux.ibm.com

arch/powerpc/include/asm/sstep.h

@@ -104,6 +104,10 @@ enum instruction_type {
 
 #define MKOP(t, f, s)	((t) | (f) | SIZE(s))
 
+/* Prefix instruction operands */
+#define GET_PREFIX_RA(i)	(((i) >> 16) & 0x1f)
+#define GET_PREFIX_R(i)		((i) & (1ul << 20))
+
 struct instruction_op {
 	int type;
 	int reg;

arch/powerpc/lib/sstep.c

@@ -200,8 +200,8 @@ static nokprobe_inline unsigned long mlsd_8lsd_ea(unsigned int instr,
 	unsigned int  dd;
 	unsigned long ea, d0, d1, d;
 
-	prefix_r = instr & (1ul << 20);
-	ra = (suffix >> 16) & 0x1f;
+	prefix_r = GET_PREFIX_R(instr);
+	ra = GET_PREFIX_RA(suffix);
 
 	d0 = instr & 0x3ffff;
 	d1 = suffix & 0xffff;
@@ -1339,8 +1339,8 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 	switch (opcode) {
 #ifdef __powerpc64__
 	case 1:
-		prefix_r = word & (1ul << 20);
-		ra = (suffix >> 16) & 0x1f;
+		prefix_r = GET_PREFIX_R(word);
+		ra = GET_PREFIX_RA(suffix);
 		rd = (suffix >> 21) & 0x1f;
 		op->reg = rd;
 		op->val = regs->gpr[rd];
@@ -2715,8 +2715,8 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 		}
 		break;
 	case 1: /* Prefixed instructions */
-		prefix_r = word & (1ul << 20);
-		ra = (suffix >> 16) & 0x1f;
+		prefix_r = GET_PREFIX_R(word);
+		ra = GET_PREFIX_RA(suffix);
 		op->update_reg = ra;
 		rd = (suffix >> 21) & 0x1f;
 		op->reg = rd;