On 2015/11/4 5:48, Laura Abbott wrote:
>
> Rather than always putting the least restrictived permissions
> (PAGE_KERNEL_EXEC) when spliting a pmd into pages, use
> the existing permissions from the pmd for the page.
>
> Signed-off-by: Laura Abbott <[email protected]>
> ---
> arch/arm64/mm/mmu.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 9211b85..ff41efa 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -75,14 +75,13 @@ static void __init *early_alloc(unsigned long sz)
> static void split_pmd(pmd_t *pmd, pte_t *pte)
> {
> unsigned long pfn = pmd_pfn(*pmd);
> + unsigned long addr = pfn << PAGE_SHIFT;
> + pgprot_t prot = __pgprot(pmd_val(*pmd) ^ addr) | PTE_TYPE_PAGE;
> +
Hi Laura,
I'm not quite understand, I find split_pud() doesn't set the flag
PMD_TYPE_TABLE. If we clear xx_TABLE_BIT, does that means the page
is large page?
And what is the different from the flag xx_TYPE_SECT?
Thanks,
Xishi Qiu
> int i = 0;
>
> do {
> - /*
> - * Need to have the least restrictive permissions available
> - * permissions will be fixed up later
> - */
> - set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
> + set_pte(pte, pfn_pte(pfn, prot));
> pfn++;
> } while (pte++, i++, i < PTRS_PER_PTE);
> }
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