Patch "powerpc: Fix emulation of mfocrf in emulate_step()" has been added to the 3.18-stable tree

Patch "powerpc: Fix emulation of mfocrf in emulate_step()" has been added to the 3.18-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    powerpc: Fix emulation of mfocrf in emulate_step()

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-fix-emulation-of-mfocrf-in-emulate_step.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 64e756c55aa46fc18fd53e8f3598b73b528d8637 Mon Sep 17 00:00:00 2001
From: Anton Blanchard <anton@samba.org>
Date: Thu, 15 Jun 2017 09:46:39 +1000
Subject: powerpc: Fix emulation of mfocrf in emulate_step()

From: Anton Blanchard <anton@samba.org>

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>

---
 arch/powerpc/lib/sstep.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -969,6 +969,19 @@ int __kprobes analyse_instr(struct instr
 #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;


Patches currently in stable-queue which might be from anton@samba.org are

queue-3.18/powerpc-fix-emulation-of-mfocrf-in-emulate_step.patch
queue-3.18/powerpc-fix-emulation-of-mcrf-in-emulate_step.patch