Christophe Leroy <christophe.le...@c-s.fr> writes:
> On the 8xx, we can have as many slices as PMD entries.
> This means we could have 1024 slices in 4k size pages mode
> and 64 slices in 16k size pages.
>
> However, due to a stack overflow in slice_get_unmapped_area(),
> we limit to 512 slices.
>
> Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
> ---
> arch/powerpc/include/asm/mmu-8xx.h | 6 +++++-
> arch/powerpc/include/asm/page_32.h | 3 ++-
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/mmu-8xx.h
> b/arch/powerpc/include/asm/mmu-8xx.h
> index d669d0062da4..40aa7b0cd0dc 100644
> --- a/arch/powerpc/include/asm/mmu-8xx.h
> +++ b/arch/powerpc/include/asm/mmu-8xx.h
> @@ -171,7 +171,11 @@ typedef struct {
> unsigned long vdso_base;
> #ifdef CONFIG_PPC_MM_SLICES
> u16 user_psize; /* page size index */
> - unsigned char low_slices_psize[8]; /* 16 slices */
> +#if defined(CONFIG_PPC_16K_PAGES)
> + unsigned char low_slices_psize[32]; /* 64 slices */
> +#else
> + unsigned char low_slices_psize[256]; /* 512 slices */
> +#endif
These #ifdef should be 8xx and then 16K.
> unsigned char high_slices_psize[0];
> unsigned long slb_addr_limit;
> #endif
> diff --git a/arch/powerpc/include/asm/page_32.h
> b/arch/powerpc/include/asm/page_32.h
> index f7d1bd1183c8..43695ce7ee07 100644
> --- a/arch/powerpc/include/asm/page_32.h
> +++ b/arch/powerpc/include/asm/page_32.h
> @@ -62,7 +62,8 @@ extern void copy_page(void *to, void *from);
>
> #ifdef CONFIG_PPC_MM_SLICES
>
> -#define SLICE_LOW_SHIFT 28
> +/* SLICE_LOW_SHIFT >= 23 to avoid stack overflow in
> slice_get_unmapped_area() */
> +#define SLICE_LOW_SHIFT (PMD_SHIFT > 23 ? PMD_SHIFT : 23)
> #define SLICE_HIGH_SHIFT 0
>
> #define SLICE_LOW_TOP (0xfffffffful)
> --
> 2.13.3
