On Mon, Apr 22, 2013 at 03:30:39PM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
[snip]
> /*
> - * Use the top bit of the higher-level page table entries to indicate whether
> - * the entries we point to contain hugepages. This works because we know
> that
> - * the page tables live in kernel space. If we ever decide to support having
> - * page tables at arbitrary addresses, this breaks and will have to change.
> - */
> -#ifdef CONFIG_PPC64
> -#define PD_HUGE 0x8000000000000000
> -#else
> -#define PD_HUGE 0x80000000
> -#endif
I think this is a good thing to do ultimately, but if you do this you
also need to fix arch/powerpc/kernel/head_fsl_booke.S:
#ifdef CONFIG_PTE_64BIT
#ifdef CONFIG_HUGETLB_PAGE
#define FIND_PTE \
rlwinm r12, r10, 13, 19, 29; /* Compute pgdir/pmd offset */ \
lwzx r11, r12, r11; /* Get pgd/pmd entry */ \
rlwinm. r12, r11, 0, 0, 20; /* Extract pt base address */ \
blt 1000f; /* Normal non-huge page */ \
beq 2f; /* Bail if no table */ \
oris r11, r11, PD_HUGE@h; /* Put back address bit */ \
andi. r10, r11, HUGEPD_SHIFT_MASK@l; /* extract size field */ \
xor r12, r10, r11; /* drop size bits from pointer */ \
b 1001f; \
and this, from arch/powerpc/mm/tlb_low_64e.S:
cmpdi cr0,r14,0
bge tlb_miss_fault_bolted /* Bad pgd entry or hugepage; bail */
(of which there are several similar instances in that file).
If you want to avoid fixing these bits of assembly code (and any
others I missed in my quick scan), you'll need to keep the definition
of PD_HUGE, at least on anything not 64-bit Book3S.
Paul.
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