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SubjectRe: [PATCH 1/2] powerpc/8xx: Merge 8M hugepage slice and basepage slice
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Le 06/02/2020 à 20:21, Christophe Leroy a écrit :
> On 8xx, slices are used because hugepages (512k or 8M) and small
> pages (4k or 16k) cannot share the same PGD entry. However, as 8M
> entirely covers two PGD entries (One PGD entry covers 4M), there
> will implicitely be no conflict between 8M pages and any other size.
> So 8M is compatible with the basepage size as well.
>
> Remove the struct slice_mask mask_8m from mm_context_t and make
> vma_mmu_pagesize() rely on vma_kernel_pagesize() as the base
> slice can now host several sizes.

I'm working on getting rid of CONFIG_PPC_MM_SLICES on the 8xx, so this
little series is probably not worth merging.

Christophe

>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> arch/powerpc/include/asm/nohash/32/mmu-8xx.h | 7 ++-----
> arch/powerpc/mm/hugetlbpage.c | 3 ++-
> 2 files changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/nohash/32/mmu-8xx.h b/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
> index 76af5b0cb16e..54f7f3362edb 100644
> --- a/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
> +++ b/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
> @@ -215,9 +215,8 @@ typedef struct {
> unsigned char low_slices_psize[SLICE_ARRAY_SIZE];
> unsigned char high_slices_psize[0];
> unsigned long slb_addr_limit;
> - struct slice_mask mask_base_psize; /* 4k or 16k */
> + struct slice_mask mask_base_psize; /* 4k or 16k or 8M */
> struct slice_mask mask_512k;
> - struct slice_mask mask_8m;
> #endif
> void *pte_frag;
> } mm_context_t;
> @@ -257,10 +256,8 @@ static inline struct slice_mask *slice_mask_for_size(mm_context_t *ctx, int psiz
> {
> if (psize == MMU_PAGE_512K)
> return &ctx->mask_512k;
> - if (psize == MMU_PAGE_8M)
> - return &ctx->mask_8m;
>
> - BUG_ON(psize != mmu_virtual_psize);
> + BUG_ON(psize != mmu_virtual_psize && psize != MMU_PAGE_8M);
>
> return &ctx->mask_base_psize;
> }
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index edf511c2a30a..0b4ab741bf09 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -551,7 +551,8 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
> unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
> {
> /* With radix we don't use slice, so derive it from vma*/
> - if (IS_ENABLED(CONFIG_PPC_MM_SLICES) && !radix_enabled()) {
> + if (IS_ENABLED(CONFIG_PPC_MM_SLICES) && !IS_ENABLED(CONFIG_PPC_8xx) &&
> + !radix_enabled()) {
> unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
>
> return 1UL << mmu_psize_to_shift(psize);
>

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