Re: [RFC PATCH v2 14/27] mm: Handle THP/HugeTLB shadow stack page fault

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, Jul 10, 2018 at 03:26:26PM -0700, Yu-cheng Yu wrote:
> diff --git a/mm/memory.c b/mm/memory.c
> index a2695dbc0418..f7c46d61eaea 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4108,7 +4108,13 @@ static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
>  			if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
>  				return do_huge_pmd_numa_page(&vmf, orig_pmd);
>  
> -			if (dirty && !pmd_write(orig_pmd)) {
> +			/*
> +			 * Shadow stack trans huge PMDs are copy-on-access,
> +			 * so wp_huge_pmd() on them no mater if we have a
> +			 * write fault or not.
> +			 */
> +			if (is_shstk_mapping(vma->vm_flags) ||
> +			    (dirty && !pmd_write(orig_pmd))) {
>  				ret = wp_huge_pmd(&vmf, orig_pmd);
>  				if (!(ret & VM_FAULT_FALLBACK))
>  					return ret;

Can't we do this (and the do_wp_page thing) by setting FAULT_FLAG_WRITE
in the arch fault handler on shadow stack faults?
--
To unsubscribe from this list: send the line "unsubscribe linux-doc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux FS]     [Yosemite Forum]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Device Mapper]     [Linux Resources]

  Powered by Linux