Re: [PATCH v2 00/15] powerpc/32s: Use BATs/LTLBs for STRICT_KERNEL_RWX

[Christophe Leroy]

Le 16/01/2019 Ã 14:16, Jonathan NeuschÃfer a ÃcritÂ:
> On Wed, Jan 16, 2019 at 07:55:29AM +0100, Christophe Leroy wrote:
> > Le 16/01/2019 Ã 01:35, Jonathan NeuschÃfer a ÃcritÂ:
> > > Thinning the kernel down a bit actually makes it boot again. Ooops...!
> > > Maybe enabling CONFIG_STRICT_KERNEL_RWX has made it just large enough to
> > > fail the hash table allocation, but there may have been other factors
> > > involved (I'm not sure exactly).  Sorry for the confusion!
> >
> > Ok, that must be the reason. Thanks for testing.
> >
> > What about the following modification which maps a second 256Mb BAT, does it
> > helps ?
> >
> >
> >
> > diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
> > index c2f564690778..ea574596de37 100644
> > --- a/arch/powerpc/kernel/head_32.S
> > +++ b/arch/powerpc/kernel/head_32.S
> > @@ -1160,6 +1160,14 @@ initial_bats:
> >   	mtspr	SPRN_DBAT0U,r11		/* bit in upper BAT register */
> >   	mtspr	SPRN_IBAT0L,r8
> >   	mtspr	SPRN_IBAT0U,r11
> > +#ifdef CONFIG_WII
> > +	addis	r11,r11,0x10000000@h
> > +	addis	r8,r8,0x10000000@h
> > +	mtspr	SPRN_DBAT2L,r8
> > +	mtspr	SPRN_DBAT2U,r11
> > +	mtspr	SPRN_IBAT2L,r8
> > +	mtspr	SPRN_IBAT2U,r11
> > +#endif
> >   	isync
> >   	blr
> >
> > diff --git a/arch/powerpc/mm/ppc_mmu_32.c b/arch/powerpc/mm/ppc_mmu_32.c
> > index 3f4193201ee7..a334fd5210a8 100644
> > --- a/arch/powerpc/mm/ppc_mmu_32.c
> > +++ b/arch/powerpc/mm/ppc_mmu_32.c
> > @@ -259,6 +259,8 @@ void setup_initial_memory_limit(phys_addr_t
> > first_memblock_base,
> >   	/* 601 can only access 16MB at the moment */
> >   	if (PVR_VER(mfspr(SPRN_PVR)) == 1)
> >   		memblock_set_current_limit(min_t(u64, first_memblock_size, 0x01000000));
> > +	else if (IS_ENABLED(CONFIG_WII))
> > +		memblock_set_current_limit(min_t(u64, first_memblock_size, 0x20000000));
> >   	else /* Anything else has 256M mapped */
> >   		memblock_set_current_limit(min_t(u64, first_memblock_size, 0x10000000));
> >   }
>
> I haven't tested it, but this patch won't be enough, because we're only
> looking at the first memblock, and the additional memory in the Wii
> (MEM2) is the second memblock.

Yes right.


Would the following work instead ?

memblock_set_current_limit(0x20000000);


Christophe