[PATCH v4 3/5] powerpc/lib/sstep: Add bpermd instruction emulation

[Matt Brown]

This adds emulation for the bpermd instruction.
Tested for correctness against the bpermd instruction on ppc64le.

Signed-off-by: Matt Brown <matthew.brown.dev at gmail.com>
---
v4:
	- change ifdef macro from __powerpc64__ to CONFIG_PPC64
v2:
	- fixed opcode
	- added ifdef tags to do_bpermd func
	- fixed bitshifting errors
---
 arch/powerpc/lib/sstep.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 2fd7377..c9fd613 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -640,6 +640,24 @@ static nokprobe_inline void do_popcnt(struct pt_regs *regs, unsigned long v1,
 	regs->gpr[ra] = out;	/* popcntd */
 }
 
+#ifdef CONFIG_PPC64
+static nokprobe_inline void do_bpermd(struct pt_regs *regs, unsigned long v1,
+				unsigned long v2, int ra)
+{
+	unsigned char perm, idx;
+	unsigned int i;
+
+	perm = 0;
+	for (i = 0; i < 8; i++) {
+		idx = (v1 >> (i * 8)) & 0xff;
+		if (idx < 64)
+			if (v2 & PPC_BIT(idx))
+				perm |= 1 << i;
+	}
+	regs->gpr[ra] = perm;
+}
+#endif /* CONFIG_PPC64 */
+
 static nokprobe_inline int trap_compare(long v1, long v2)
 {
 	int ret = 0;
@@ -1229,7 +1247,11 @@ 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;
-
+#ifdef CONFIG_PPC64
+		case 252:	/* bpermd */
+			do_bpermd(regs, regs->gpr[rd], regs->gpr[rb], ra);
+			goto logical_done;
+#endif
 		case 284:	/* xor */
 			regs->gpr[ra] = ~(regs->gpr[rd] ^ regs->gpr[rb]);
 			goto logical_done;
-- 
2.9.3