Instead of copying the exception vectors from ROM to page zero use the Interrupt Prefix bit of the CPU to use the vectors at the ROM address. This simplifies the startup routine a little bit and avoids using addresses that can be overwritten by clients. In particular MorphOS writes to address 0x80 during boot which corrupted the exception return code causing a crash.
Signed-off-by: BALATON Zoltan balaton@eik.bme.hu ---
Index: openbios-devel/arch/ppc/qemu/start.S =================================================================== --- openbios-devel/arch/ppc/qemu/start.S (revision 1304) +++ openbios-devel/arch/ppc/qemu/start.S (working copy) @@ -388,7 +388,7 @@ GLOBL(__vectors_end): GLOBL(_entry):
#ifdef CONFIG_PPC_64BITSUPPORT - li r0,0 + li r0, MSR_IP
lis r3, 0x8000 /* r1=0x80000000 */ add. r3,r3,r3 /* r1=r1+r1 (high 32bit !0) */ @@ -404,32 +404,6 @@ no_64bit:
real_entry: #endif - - /* copy exception vectors */ - - LOAD_REG_IMMEDIATE(r3, __vectors) - li r4,0 - li r5,__vectors_end - __vectors + 16 - rlwinm r5,r5,0,0,28 -1: lwz r6,0(r3) - lwz r7,4(r3) - lwz r8,8(r3) - lwz r9,12(r3) - stw r6,0(r4) - stw r7,4(r4) - stw r8,8(r4) - stw r9,12(r4) - dcbst 0,r4 - sync - icbi 0,r4 - sync - addi r5,r5,-16 - addi r3,r3,16 - addi r4,r4,16 - cmpwi r5,0 - bgt 1b - isync - bl compute_ramsize
/* Memory map: @@ -521,13 +495,13 @@ _GLOBAL(call_elf): LOAD_REG_IMMEDIATE(r5, of_client_callback) // r5 = callback li r6,0 // r6 = address of client program arguments (unused) li r7,0 // r7 = length of client program arguments (unused) - li r0,MSR_FP | MSR_ME | MSR_DR | MSR_IR + li r0,MSR_FP | MSR_ME | MSR_IP | MSR_DR | MSR_IR MTMSRD(r0) blrl
#ifdef CONFIG_PPC64 /* Restore SF bit */ - LOAD_REG_IMMEDIATE(r0, MSR_SF | MSR_FP | MSR_ME | MSR_DR | MSR_IR) + LOAD_REG_IMMEDIATE(r0, MSR_SF | MSR_FP | MSR_ME | MSR_IP | MSR_DR | MSR_IR) MTMSRD(r0) #endif LOAD_REG_IMMEDIATE(r8, saved_stack) // restore stack pointer