[PATCH] arm: Preserve L_PTE_VALID in pte_modify()

[Will Deacon]

On Tue, Feb 12, 2013 at 06:25:50PM +0000, Catalin Marinas wrote:
> Following commit 26ffd0d4 (ARM: mm: introduce present, faulting entries
> for PAGE_NONE), if a page has been mapped as PROT_NONE, the L_PTE_VALID
> bit is cleared by the set_pte_ext() code. With LPAE the software and
> hardware pte share the same location and subsequent modifications of pte
> range (change_protection()) will leave the L_PTE_VALID bit cleared.
> 
> This patch adds the L_PTE_VALID bit to the newprot mask in pte_modify().
> 
> Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
> Reported-by: Subash Patel <subash.rp at samsung.com>
> Tested-by: Subash Patel <subash.rp at samsung.com>
> Cc: Will Deacon <will.deacon at arm.com>

This matches what I did for arm64, so:

  Acked-by: Will Deacon <will.deacon at arm.com>

Cheers,

Will

> ---
>  arch/arm/include/asm/pgtable.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
> index 9c82f988..c094749 100644
> --- a/arch/arm/include/asm/pgtable.h
> +++ b/arch/arm/include/asm/pgtable.h
> @@ -240,7 +240,8 @@ static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
>  
>  static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
>  {
> -	const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER | L_PTE_NONE;
> +	const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER |
> +		L_PTE_NONE | L_PTE_VALID;
>  	pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
>  	return pte;
>  }