[PATCH 3/6] powerpc sstep: Add cnttzw, cnttzd instruction emulation

[Sandipan Das]

This adds emulation support for the following integer instructions:
  * Count Trailing Zeros Word (cnttzw[.])
  * Count Trailing Zeros Doubleword (cnttzd[.])

Signed-off-by: Sandipan Das <sandipan at linux.ibm.com>
---
 arch/powerpc/lib/sstep.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 18ac0a26c4fc..d57cb4e28621 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1816,6 +1816,20 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 		case 506:	/* popcntd */
 			do_popcnt(regs, op, regs->gpr[rd], 64);
 			goto logical_done_nocc;
+#endif
+		case 538:	/* cnttzw */
+			if (!cpu_has_feature(CPU_FTR_ARCH_300))
+				return -1;
+			val = (unsigned int) regs->gpr[rd];
+			op->val = ( val ? __builtin_ctz(val) : 32 );
+			goto logical_done;
+#ifdef __powerpc64__
+		case 570:	/* cnttzd */
+			if (!cpu_has_feature(CPU_FTR_ARCH_300))
+				return -1;
+			val = regs->gpr[rd];
+			op->val = ( val ? __builtin_ctzl(val) : 64 );
+			goto logical_done;
 #endif
 		case 922:	/* extsh */
 			op->val = (signed short) regs->gpr[rd];
-- 
2.14.4