Re: [PATCH 05/14] uaccess: add generic __{get,put}_kernel_nofault

From: Arnd Bergmann <arnd@kernel.org>
To: Al Viro <viro@zeniv.linux.org.uk>
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Subject: Re: [PATCH 05/14] uaccess: add generic __{get,put}_kernel_nofault
Date: Tue, 15 Feb 2022 14:16:50 +0100	[thread overview]
Message-ID: <CAK8P3a2+qG=Q9Si_2D7wjM7Qao2JCnYqKgU=W-SFwoG+fT-U3A@mail.gmail.com> (raw)
In-Reply-To: <Ygr0eAA+ZR1eX0wb@zeniv-ca.linux.org.uk>

On Tue, Feb 15, 2022 at 1:31 AM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Mon, Feb 14, 2022 at 05:34:43PM +0100, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > All architectures that don't provide __{get,put}_kernel_nofault() yet
> > can implement this on top of __{get,put}_user.
> >
> > Add a generic version that lets everything use the normal
> > copy_{from,to}_kernel_nofault() code based on these, removing the last
> > use of get_fs()/set_fs() from architecture-independent code.
>
> I'd put the list of those architectures (AFAICS, that's alpha, ia64,
> microblaze, nds32, nios2, openrisc, sh, sparc32, xtensa) into commit
> message - it's not that hard to find out, but...

done.

> And AFAICS, you've missed nios2 - see
> #define __put_user(x, ptr) put_user(x, ptr)
> in there.  nds32 oddities are dealt with earlier in the series, this
> one is not...

Ok, fixed my bug in nios2 __put_user() as well now. This one is not nearly
as bad as nds32, at least without my patches it should work as expected.

Unfortunately I also noticed that __get_user() on microblaze and nios2
is completely broken for 64-bit arguments, where these copy eight bytes
into a four byte buffer. I'll try to come up with a fix for this as well then.

         Arnd