Re: [PATCHv3 5/8] x86/uaccess: Provide untagged_addr() and remove tags before address check

H.J. Lu
2022-06-17T14:23:41Z

On Fri, Jun 17, 2022 at 4:36 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Thu, Jun 16, 2022 at 07:44:40PM +0300, Kirill A. Shutemov wrote:
> > Any objection against this variant (was posted in the thread):
> >
> > #define untagged_addr(mm, addr) ({ \
> > u64 __addr = (__force u64)(addr); \
> > s64 sign = (s64)__addr >> 63; \
> > __addr &= (mm)->context.untag_mask | sign; \
> > (__force __typeof__(addr))__addr; \
> > })
> >
> > ?
>
> Yeah, I suppose that should work fine.

Won't the sign bit be put at the wrong place?

--
H.J.