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Commit 0b029899 authored by Anton Blanchard's avatar Anton Blanchard Committed by Greg Kroah-Hartman
Browse files

powerpc: Fix emulation of mfocrf in emulate_step() 



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: 6888199f ("[POWERPC] Emulate more instructions in software")
Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Acked-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 242aa00b

arch/powerpc/lib/sstep.c

+13 −0
Original line number Diff line number Diff line
@@ -969,6 +969,19 @@ int __kprobes 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;