Re: [PATCH v2 02/10] arm64/mm: add create_pgd_mapping() to create private page tables

[Steve Capper <steve.capper@linaro.org>]

On Thu, Nov 06, 2014 at 03:13:18PM +0100, Ard Biesheuvel wrote:

Hi Ard,
Some comments below:

> For UEFI, we need to install the memory mappings used for Runtime Services
> in a dedicated set of page tables. Add create_pgd_mapping(), which allows
> us to allocate and install those page table entries early.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  arch/arm64/include/asm/mmu.h     |  3 +++
>  arch/arm64/include/asm/pgtable.h |  5 +++++
>  arch/arm64/mm/mmu.c              | 44 +++++++++++++++++++++-------------------
>  3 files changed, 31 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
> index c2f006c48bdb..5fd40c43be80 100644
> --- a/arch/arm64/include/asm/mmu.h
> +++ b/arch/arm64/include/asm/mmu.h
> @@ -33,5 +33,8 @@ extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
>  extern void init_mem_pgprot(void);
>  /* create an identity mapping for memory (or io if map_io is true) */
>  extern void create_id_mapping(phys_addr_t addr, phys_addr_t size, int map_io);
> +extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
> +			       unsigned long virt, phys_addr_t size,
> +			       pgprot_t prot);
>  
>  #endif
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 41a43bf26492..1abe4d08725b 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -264,6 +264,11 @@ static inline pmd_t pte_pmd(pte_t pte)
>  	return __pmd(pte_val(pte));
>  }
>  
> +static inline pgprot_t mk_sect_prot(pgprot_t prot)
> +{
> +	return __pgprot(pgprot_val(prot) & ~PTE_TABLE_BIT);
> +}
> +
>  /*
>   * THP definitions.
>   */
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 83e6713143a3..b6dc2ce3991a 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -157,20 +157,10 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
>  
>  static void __init alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
>  				  unsigned long addr, unsigned long end,
> -				  phys_addr_t phys, int map_io)
> +				  phys_addr_t phys, pgprot_t prot)
>  {
>  	pmd_t *pmd;
>  	unsigned long next;
> -	pmdval_t prot_sect;
> -	pgprot_t prot_pte;
> -
> -	if (map_io) {
> -		prot_sect = PROT_SECT_DEVICE_nGnRE;
> -		prot_pte = __pgprot(PROT_DEVICE_nGnRE);
> -	} else {
> -		prot_sect = PROT_SECT_NORMAL_EXEC;
> -		prot_pte = PAGE_KERNEL_EXEC;
> -	}

Thanks :-)

>  
>  	/*
>  	 * Check for initial section mappings in the pgd/pud and remove them.
> @@ -186,7 +176,8 @@ static void __init alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
>  		/* try section mapping first */
>  		if (((addr | next | phys) & ~SECTION_MASK) == 0) {
>  			pmd_t old_pmd =*pmd;
> -			set_pmd(pmd, __pmd(phys | prot_sect));
> +			set_pmd(pmd, __pmd(phys |
> +					   pgprot_val(mk_sect_prot(prot))));
>  			/*
>  			 * Check for previous table entries created during
>  			 * boot (__create_page_tables) and flush them.
> @@ -195,7 +186,7 @@ static void __init alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
>  				flush_tlb_all();
>  		} else {
>  			alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys),
> -				       prot_pte);
> +				       prot);
>  		}
>  		phys += next - addr;
>  	} while (pmd++, addr = next, addr != end);
> @@ -203,7 +194,7 @@ static void __init alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
>  
>  static void __init alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
>  				  unsigned long addr, unsigned long end,
> -				  unsigned long phys, int map_io)
> +				  unsigned long phys, pgprot_t prot)
>  {
>  	pud_t *pud;
>  	unsigned long next;
> @@ -221,10 +212,11 @@ static void __init alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
>  		/*
>  		 * For 4K granule only, attempt to put down a 1GB block
>  		 */
> -		if (!map_io && (PAGE_SHIFT == 12) &&
> +		if ((PAGE_SHIFT == 12) &&
>  		    ((addr | next | phys) & ~PUD_MASK) == 0) {
>  			pud_t old_pud = *pud;
> -			set_pud(pud, __pud(phys | PROT_SECT_NORMAL_EXEC));
> +			set_pud(pud, __pud(phys |
> +					   pgprot_val(mk_sect_prot(prot))));
>  
>  			/*
>  			 * If we have an old value for a pud, it will
> @@ -239,7 +231,7 @@ static void __init alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
>  				flush_tlb_all();
>  			}
>  		} else {
> -			alloc_init_pmd(mm, pud, addr, next, phys, map_io);
> +			alloc_init_pmd(mm, pud, addr, next, phys, prot);
>  		}
>  		phys += next - addr;
>  	} while (pud++, addr = next, addr != end);
> @@ -251,7 +243,7 @@ static void __init alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
>   */
>  static void __init __create_mapping(struct mm_struct *mm, pgd_t *pgd,
>  				    phys_addr_t phys, unsigned long virt,
> -				    phys_addr_t size, int map_io)
> +				    phys_addr_t size, pgprot_t prot)
>  {
>  	unsigned long addr, length, end, next;
>  
> @@ -261,7 +253,8 @@ static void __init __create_mapping(struct mm_struct *mm, pgd_t *pgd,
>  	end = addr + length;
>  	do {
>  		next = pgd_addr_end(addr, end);
> -		alloc_init_pud(mm, pgd, addr, next, phys, map_io);
> +		alloc_init_pud(mm, pgd, addr, next, phys, prot);
> +			       
>  		phys += next - addr;
>  	} while (pgd++, addr = next, addr != end);
>  }
> @@ -275,7 +268,7 @@ static void __init create_mapping(phys_addr_t phys, unsigned long virt,
>  		return;
>  	}
>  	__create_mapping(&init_mm, pgd_offset_k(virt & PAGE_MASK), phys, virt,
> -			 size, 0);
> +			 size, PAGE_KERNEL_EXEC);
>  }
>  
>  void __init create_id_mapping(phys_addr_t addr, phys_addr_t size, int map_io)
> @@ -285,7 +278,16 @@ void __init create_id_mapping(phys_addr_t addr, phys_addr_t size, int map_io)
>  		return;
>  	}
>  	__create_mapping(&init_mm, &idmap_pg_dir[pgd_index(addr)],
> -			 addr, addr, size, map_io);
> +			 addr, addr, size,
> +			 map_io ? __pgprot(PROT_DEVICE_nGnRE)
> +				: PAGE_KERNEL_EXEC);
> +}

Could you please also change efi_setup_idmap (it's the only caller I
can see for create_id_mapping)?

That way the prototype for create_id_mapping would look like:
void __init create_id_mapping(phys_addr_t addr, phys_addr_t size, pgprot_t prot)

> +
> +void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
> +			       unsigned long virt, phys_addr_t size,
> +			       pgprot_t prot)
> +{
> +	__create_mapping(mm, pgd_offset(mm, virt), phys, virt, size, prot);
>  }
>  
>  static void __init map_mem(void)
> -- 
> 1.8.3.2
> 

Cheers,
-- 
Steve