target-ppc: Fix SRR0 when taking unaligned exceptions

target-ppc: Fix SRR0 when taking unaligned exceptions

We are setting SRR0 to the instruction before the one causing the
unaligned exception. A quick testcase:

. = 0x100
.globl _start
_start:
	/* Cause a 0x600 */
	li	3,0x1
	stwcx.	3,0,3
1:	b	1b

. = 0x600
1:	b	1b

Built into something we can load as a BIOS image:

gcc -mbig -c test.S
ld -EB -Ttext 0x0 -o test test.o
objcopy -O binary test test.bin

Run with:

qemu-system-ppc64 -nographic -bios test.bin

Shows an incorrect SRR0 (points at the li):

SRR0 0000000000000100

With the patch we get the correct SRR0:

SRR0 0000000000000104

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>