Re: [OpenBIOS] [commit] r1043 - trunk/openbios-devel/arch/ppc/qemu

[Andreas Färber]

Am 17.06.2011 um 02:55 schrieb repository service:
> Author: agraf
> Date: Fri Jun 17 02:55:02 2011
> New Revision: 1043
> URL: http://tracker.coreboot.org/trac/openbios/changeset/1043
>
> Log:
> ppc: fix mtmsr for SF setting
>
> When running openbios-ppc32 on a ppc64 VM, we need to unset SF on  
> every
> interrupt to ensure that things still work.
>
> So far we've been using mtmsr for this operation, but according to the
> spec mtmsr doesn't set any bit above 32bit, so we were merely  
> exploiting
> a bug in qemu before.
>
> This patch adds a runtime check on MSR_SF to see if we're running on  
> a 64-bit
> capable CPU. If so, we use mtmsrd, which can set the high 32bits of  
> MSR.
>
> CC: Andreas Färber 
> CC: Segher Boessenkool 
> Signed-off-by: Alexander Graf
>
> v1 -> v2:
> use segher's awesome MSR_SF detection
>
> Modified:
>   trunk/openbios-devel/arch/ppc/qemu/start.S
>
> Modified: trunk/openbios-devel/arch/ppc/qemu/start.S
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- trunk/openbios-devel/arch/ppc/qemu/start.S	Fri Jun 17 02:55:00  
> 2011	(r1042)
> +++ trunk/openbios-devel/arch/ppc/qemu/start.S	Fri Jun 17 02:55:02  
> 2011	(r1043)
> @@ -37,9 +37,16 @@
>
> #define EXCEPTION_PREAMBLE_TEMPLATE \
>    mtsprg1	r1 ;				/* scratch */ \
> mfcr	r1 ; \
> mtsprg2	r1 ;				/* scratch */ \
> lis	r1, 0x8000 ;			/* r1=0x80000000 */ \
> add.	r1,r1,r1 ;			/* r1=r1+r1 (high 32bit !0) */ \
> beq	1f; \
> \

This is more readable than the previous version, thanks.
> mfmsr	r1 ;				/* unset MSR_SF */ \
>    clrlwi	r1,r1,0 ; \
> mtmsr	r1 ; \
> mtmsrd	r1 ; \
>
> +1: \
>    mfsprg0	r1 ;				/* exception stack in sprg0 */ \
> .ifc ULONG_SIZE, 8 ; \
>    addi	r1,r1,-(40 * ULONG_SIZE) ;	/* push exception frame */ \
> @@ -85,7 +92,7 @@
>  \
>    mflr	r0 ; \
>    stl	r0,(13 * ULONG_SIZE)(r1) ; \
> mfcr	r0 ; \
> mfsprg2	r0 ; \
> stl	r0,(14 * ULONG_SIZE)(r1) ; \
> mfctr	r0 ; \
> stl	r0,(15 * ULONG_SIZE)(r1) ; \
>
> @@ -301,14 +308,12 @@
> ILLEGAL_VECTOR( 0x200 )
>
> VECTOR( 0x300, "DSI" ):
> EXCEPTION_PREAMBLE
> b	call_dsi_exception
> b	real_dsi
>
> ILLEGAL_VECTOR( 0x380 )
>
> VECTOR( 0x400, "ISI" ):
> EXCEPTION_PREAMBLE
> b	call_isi_exception
> b	real_isi
>
> ILLEGAL_VECTOR( 0x480 )
>
> @@ -359,6 +364,14 @@
>
> #endif
>
> +real_dsi:
> EXCEPTION_PREAMBLE
> b	call_dsi_exception
>
> +real_isi:
> EXCEPTION_PREAMBLE
> b	call_isi_exception

I don't like the naming "real_xxx".

Have you checked that the serial output still has the same vector  
number (+4)?

Andreas
> GLOBL(__vectors_end):
>
> / 
> ************************************************************************/
> @@ -368,10 +381,21 @@
> GLOBL(_entry):
>
> #ifdef CONFIG_PPC_64BITSUPPORT
> /* clear MSR, disable MMU */
> li	r0,0
> lis	r3, 0x8000			/* r1=0x80000000 */
> add.	r3,r3,r3			/* r1=r1+r1 (high 32bit !0) */
> beq	no_64bit			/* only true when !MSR_SF */
> /* clear MSR, disable MMU, SF */
> mtmsrd	r0
> b	real_entry
>
> +no_64bit:
> /* clear MSR, disable MMU */
> mtmsr	r0
>
> +real_entry:
> #endif
>
> /* copy exception vectors */