Re: get rid of the address_space override in setsockopt

To: David Laight <David.Laight@xxxxxxxxxx>
Subject: Re: get rid of the address_space override in setsockopt
Cc: 'Christoph Hellwig' <hch@xxxxxx>, "David S. Miller" <davem@xxxxxxxxxxxxx>, Jakub Kicinski <kuba@xxxxxxxxxx>, Alexei Starovoitov <ast@xxxxxxxxxx>, Daniel Borkmann <daniel@xxxxxxxxxxxxx>, Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>, Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx>, Eric Dumazet <edumazet@xxxxxxxxxx>, "linux-crypto@xxxxxxxxxxxxxxx" <linux-crypto@xxxxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, "netdev@xxxxxxxxxxxxxxx" <netdev@xxxxxxxxxxxxxxx>, "bpf@xxxxxxxxxxxxxxx" <bpf@xxxxxxxxxxxxxxx>, "netfilter-devel@xxxxxxxxxxxxxxx" <netfilter-devel@xxxxxxxxxxxxxxx>, "coreteam@xxxxxxxxxxxxx" <coreteam@xxxxxxxxxxxxx>, "linux-sctp@xxxxxxxxxxxxxxx" <linux-sctp@xxxxxxxxxxxxxxx>, "linux-hams@xxxxxxxxxxxxxxx" <linux-hams@xxxxxxxxxxxxxxx>, "linux-bluetooth@xxxxxxxxxxxxxxx" <linux-bluetooth@xxxxxxxxxxxxxxx>, "bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx" <bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx>, "linux-can@xxxxxxxxxxxxxxx" <linux-can@xxxxxxxxxxxxxxx>, "dccp@xxxxxxxxxxxxxxx" <dccp@xxxxxxxxxxxxxxx>, "linux-decnet-user@xxxxxxxxxxxxxxxxxxxxx" <linux-decnet-user@xxxxxxxxxxxxxxxxxxxxx>, "linux-wpan@xxxxxxxxxxxxxxx" <linux-wpan@xxxxxxxxxxxxxxx>, "linux-s390@xxxxxxxxxxxxxxx" <linux-s390@xxxxxxxxxxxxxxx>, "mptcp@xxxxxxxxxxxx" <mptcp@xxxxxxxxxxxx>, "lvs-devel@xxxxxxxxxxxxxxx" <lvs-devel@xxxxxxxxxxxxxxx>, "rds-devel@xxxxxxxxxxxxxx" <rds-devel@xxxxxxxxxxxxxx>, "linux-afs@xxxxxxxxxxxxxxxxxxx" <linux-afs@xxxxxxxxxxxxxxxxxxx>, "tipc-discussion@xxxxxxxxxxxxxxxxxxxxx" <tipc-discussion@xxxxxxxxxxxxxxxxxxxxx>, "linux-x25@xxxxxxxxxxxxxxx" <linux-x25@xxxxxxxxxxxxxxx>
From: 'Christoph Hellwig' <hch@xxxxxx>
Date: Wed, 22 Jul 2020 10:07:24 +0200
On Tue, Jul 21, 2020 at 10:26:58AM +0000, David Laight wrote:
> From: Christoph Hellwig
> > Sent: 20 July 2020 13:47
> > 
> > setsockopt is the last place in architecture-independ code that still
> > uses set_fs to force the uaccess routines to operate on kernel pointers.
> > 
> > This series adds a new sockptr_t type that can contained either a kernel
> > or user pointer, and which has accessors that do the right thing, and
> > then uses it for setsockopt, starting by refactoring some low-level
> > helpers and moving them over to it before finally doing the main
> > setsockopt method.
> Another 'gotcha' ...
> On an least some architectures (possibly only m68k) IIRC all structures
> are actually passed by reference.
> (This used to be true for sparc - but it may have changed in the
> last 30 years.)

Tough luck for ABIs wit suboptimal calling conventions.  At least we can
do the right thing for those that do not have the problem.

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