[PATCH v2 21/34] ARM: mmu: alloc 64k for early page tables

[Ahmad Fatoum]

On 17.05.23 11:03, Sascha Hauer wrote:
> This is a preparation for using two level page tables in the PBL.
> To do that we need a way to allocate page tables in PBL. As malloc
> is not available in PBL, increase the area we use for the TTB to
> make some space available for page tables.
> 
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>

Reviewed-by: Ahmad Fatoum <a.fatoum at pengutronix.de>

> ---
>  arch/arm/cpu/mmu_32.c              | 6 ++++++
>  arch/arm/include/asm/barebox-arm.h | 8 ++------
>  2 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm/cpu/mmu_32.c b/arch/arm/cpu/mmu_32.c
> index 12fe892400..4050d96846 100644
> --- a/arch/arm/cpu/mmu_32.c
> +++ b/arch/arm/cpu/mmu_32.c
> @@ -24,6 +24,12 @@
>  #define PTRS_PER_PTE		(PGDIR_SIZE / PAGE_SIZE)
>  #define ARCH_MAP_WRITECOMBINE	((unsigned)-1)
>  
> +/*
> + * We have a 4GiB address space split into 1MiB sections, with each
> + * section header taking 4 bytes
> + */
> +#define ARM_TTB_SIZE	(SZ_4G / SZ_1M * sizeof(u32))
> +
>  static uint32_t *ttb;
>  
>  /*
> diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
> index f5a74b4746..eb31ca2788 100644
> --- a/arch/arm/include/asm/barebox-arm.h
> +++ b/arch/arm/include/asm/barebox-arm.h
> @@ -23,11 +23,7 @@
>  #include <asm/reloc.h>
>  #include <linux/stringify.h>
>  
> -/*
> - * We have a 4GiB address space split into 1MiB sections, with each
> - * section header taking 4 bytes
> - */
> -#define ARM_TTB_SIZE	(SZ_4G / SZ_1M * sizeof(u32))
> +#define ARM_EARLY_PAGETABLE_SIZE	SZ_64K
>  
>  void __noreturn barebox_arm_entry(unsigned long membase, unsigned long memsize, void *boarddata);
>  
> @@ -89,7 +85,7 @@ static inline unsigned long arm_mem_stack(unsigned long endmem)
>  static inline unsigned long arm_mem_ttb(unsigned long endmem)
>  {
>  	endmem = arm_mem_stack(endmem);
> -	endmem = ALIGN_DOWN(endmem, ARM_TTB_SIZE) - ARM_TTB_SIZE;
> +	endmem = ALIGN_DOWN(endmem, ARM_EARLY_PAGETABLE_SIZE) - ARM_EARLY_PAGETABLE_SIZE;
>  
>  	return endmem;
>  }

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