Subject: [PATCH v2 5/5] powerpc/lib/sstep: Add isel instruction emulation

From: Matt Brown <[email-masked]>
Date: Mon, 24 Jul 2017 11:01:09 +1000

This adds emulation for the isel instruction.
Tested for correctness against the isel instruction and its extended
mnemonics (lt, gt, eq) on ppc64le.

Signed-off-by: Matt Brown <[email-masked]>
---
v2:
	- fixed opcode
	- fixed definition to include the 'if RA=0, a=0' clause
	- fixed ccr bitshifting error
---
 arch/powerpc/lib/sstep.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index b08eb96..e1f4ec6 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1246,6 +1246,17 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs,
 /*
  * Logical instructions
  */
+		case 15:	/* isel */
+			mb = (instr >> 6) & 0x1f; /* bc */
+			val = (regs->ccr >> (31 - mb)) & 1;
+			val2 = (ra) ? regs->gpr[ra] : 0;
+
+			if (val)
+				regs->gpr[rd] = val2;
+			else
+				regs->gpr[rd] = regs->gpr[rb];
+			goto logical_done;
+
 		case 26:	/* cntlzw */
 			asm("cntlzw %0,%1" : "=r" (regs->gpr[ra]) :
 			    "r" (regs->gpr[rd]));
-- 
2.9.3