From: Anton Blanchard <anton@samba.org>
Date: Thu, 15 Jun 2017 09:46:39 +1000
Subject: [PATCH] powerpc: Fix emulation of mfocrf in emulate_step()
References: bnc#1060662
Patch-mainline: v4.12.4
Git-commit: 64e756c55aa46fc18fd53e8f3598b73b528d8637

commit 64e756c55aa46fc18fd53e8f3598b73b528d8637 upstream.

From POWER4 onwards, mfocrf() only places the specified CR field into
the destination GPR, and the rest of it is set to 0. The PowerPC AS
from version 3.0 now requires this behaviour.

The emulation code currently puts the entire CR into the destination GPR.
Fix it.

Fixes: 6888199f7fe5 ("[POWERPC] Emulate more instructions in software")
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 arch/powerpc/lib/sstep.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index fb84f51b1f0b..ee33327686ae 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -966,6 +966,19 @@ int analyse_instr(struct instruction_op *op, struct pt_regs *regs,
 #endif
 
 		case 19:	/* mfcr */
+			if ((instr >> 20) & 1) {
+				imm = 0xf0000000UL;
+				for (sh = 0; sh < 8; ++sh) {
+					if (instr & (0x80000 >> sh)) {
+						regs->gpr[rd] = regs->ccr & imm;
+						break;
+					}
+					imm >>= 4;
+				}
+
+				goto instr_done;
+			}
+
 			regs->gpr[rd] = regs->ccr;
 			regs->gpr[rd] &= 0xffffffffUL;
 			goto instr_done;
-- 
2.14.2