On 6/11/19 8:40 AM, Christoph Hellwig wrote:
> Add a helper to untag a user pointer. This is needed for ADI support
> in get_user_pages_fast.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> arch/sparc/include/asm/pgtable_64.h | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
Looks good to me.
Reviewed-by: Khalid Aziz <khalid.aziz@xxxxxxxxxx>
>
> diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> index f0dcf991d27f..1904782dcd39 100644
> --- a/arch/sparc/include/asm/pgtable_64.h
> +++ b/arch/sparc/include/asm/pgtable_64.h
> @@ -1076,6 +1076,28 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
> }
> #define io_remap_pfn_range io_remap_pfn_range
>
> +static inline unsigned long untagged_addr(unsigned long start)
> +{
> + if (adi_capable()) {
> + long addr = start;
> +
> + /* If userspace has passed a versioned address, kernel
> + * will not find it in the VMAs since it does not store
> + * the version tags in the list of VMAs. Storing version
> + * tags in list of VMAs is impractical since they can be
> + * changed any time from userspace without dropping into
> + * kernel. Any address search in VMAs will be done with
> + * non-versioned addresses. Ensure the ADI version bits
> + * are dropped here by sign extending the last bit before
> + * ADI bits. IOMMU does not implement version tags.
> + */
> + return (addr << (long)adi_nbits()) >> (long)adi_nbits();
> + }
> +
> + return start;
> +}
> +#define untagged_addr untagged_addr
> +
> #include <asm/tlbflush.h>
> #include <asm-generic/pgtable.h>
>
>
