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SubjectRe: [PATCH] bitmap: separate bitmap parsing for user buffer and kernel buffer
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Andrew Morton <akpm@osdl.org> writes:

> On Wed, 4 Oct 2006 17:56:30 -0700
> Reinette Chatre <reinette.chatre@linux.intel.com> wrote:
>
> > + if (is_user) {
> > + if (__get_user(c, buf++))
> > + return -EFAULT;
> > + }
> > + else
> > + c = *buf++;
>
> Is this actually needed? __get_user(kernel_address) works OK and (believe
> it or not, given all the stuff it involves) boils down to a single instruction.

It is needed on lots of architectures that use separate address spaces
like sparc64, m68k, s390 (and on x86 with 4:4 patches)

-Andi
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