[PATCH] powerpc: Fix 460EX/460GT machine check handling

[PATCH] powerpc: Fix 460EX/460GT machine check handling

[Benjamin Herrenschmidt]

Those cores use the 440A type machine check (ie, they have
MCSRR0/MCSRR1). They thus need to call the appropriate fixup
function to hook the right variant of the exception.

Without this, all machine checks become fatal due to loss
of context when entering the exception handler.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

 arch/powerpc/kernel/cpu_setup_44x.S |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- linux-work.orig/arch/powerpc/kernel/cpu_setup_44x.S	2008-11-12 12:51:24.000000000 +1100
+++ linux-work/arch/powerpc/kernel/cpu_setup_44x.S	2008-11-12 13:01:03.000000000 +1100
@@ -34,7 +34,12 @@ _GLOBAL(__setup_cpu_440grx)
 	blr
 _GLOBAL(__setup_cpu_460ex)
 _GLOBAL(__setup_cpu_460gt)
-	b	__init_fpu_44x
+	mflr	r4
+	bl	__init_fpu_44x
+	bl	__fixup_440A_mcheck
+	mtlr	r4
+	blr
+
 _GLOBAL(__setup_cpu_440gx)
 _GLOBAL(__setup_cpu_440spe)
 	b	__fixup_440A_mcheck

Re: [PATCH] powerpc: Fix 460EX/460GT machine check handling

[Josh Boyer]

On Wed, 12 Nov 2008 13:02:43 +1100
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

> Those cores use the 440A type machine check (ie, they have
> MCSRR0/MCSRR1). They thus need to call the appropriate fixup
> function to hook the right variant of the exception.
> 
> Without this, all machine checks become fatal due to loss
> of context when entering the exception handler.

Looks fine to me.  However, what machine checks were you getting that
caused you to see this that aren't fatal anyway?

josh

> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
> 
>  arch/powerpc/kernel/cpu_setup_44x.S |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> --- linux-work.orig/arch/powerpc/kernel/cpu_setup_44x.S	2008-11-12 12:51:24.000000000 +1100
> +++ linux-work/arch/powerpc/kernel/cpu_setup_44x.S	2008-11-12 13:01:03.000000000 +1100
> @@ -34,7 +34,12 @@ _GLOBAL(__setup_cpu_440grx)
>  	blr
>  _GLOBAL(__setup_cpu_460ex)
>  _GLOBAL(__setup_cpu_460gt)
> -	b	__init_fpu_44x
> +	mflr	r4
> +	bl	__init_fpu_44x
> +	bl	__fixup_440A_mcheck
> +	mtlr	r4
> +	blr
> +
>  _GLOBAL(__setup_cpu_440gx)
>  _GLOBAL(__setup_cpu_440spe)
>  	b	__fixup_440A_mcheck

Re: [PATCH] powerpc: Fix 460EX/460GT machine check handling

[Benjamin Herrenschmidt]

On Wed, 2008-11-12 at 06:27 -0500, Josh Boyer wrote:
> On Wed, 12 Nov 2008 13:02:43 +1100
> Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
> 
> > Those cores use the 440A type machine check (ie, they have
> > MCSRR0/MCSRR1). They thus need to call the appropriate fixup
> > function to hook the right variant of the exception.
> > 
> > Without this, all machine checks become fatal due to loss
> > of context when entering the exception handler.
> 
> Looks fine to me.  However, what machine checks were you getting that
> caused you to see this that aren't fatal anyway?

PCI aborts from userspace when toying with video card POSTing &
x86emu :-)

Cheers,
Ben.