From: Juergen Gross

Sent: 12 May 2021 09:58

On 12.05.21 10:50, 'Joerg Roedel' wrote:

quoted

On Wed, May 12, 2021 at 10:16:12AM +0200, Juergen Gross wrote:

quoted

You want something like xen_safe_[read|write]_ulong().

 From a first glance I can't see it, what is the difference between the
xen_safe_*_ulong() functions and __get_user()/__put_user()? The only
difference I can see is that __get/__put_user() support different access
sizes, but neither of those disables page-faults by itself, for example.

Couldn't these xen-specific functions not also be replaces by
__get_user()/__put_user()?

No, those were used before, but commit 9da3f2b7405440 broke Xen's use
case. That is why I did commit 1457d8cf7664f.

I've just looked at 9da3f2b7405440.

It doesn't look right to me - wrong return value for a lot of cases.
OTOH it isn't in my newest tree at all.

If bogus_uaccess() is now elsewhere I can't see how (without changes)
it would allow through these faults.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)