[PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag
Al Viro
viro at zeniv.linux.org.uk
Sun Sep 20 02:57:45 UTC 2020
On Sat, Sep 19, 2020 at 05:14:41PM -0700, Andy Lutomirski wrote:
> > 2) have you counted the syscalls that do and do not need that?
>
> No.
Might be illuminating...
> > 3) how many of those realistically *can* be unified with their
> > compat counterparts? [hint: ioctl(2) cannot]
>
> There would be no requirement to unify anything. The idea is that
> we'd get rid of all the global state flags.
_What_ global state flags? When you have separate SYSCALL_DEFINE3(ioctl...)
and COMPAT_SYSCALL_DEFINE3(ioctl...), there's no flags at all, global or
local. They only come into the play when you try to share the same function
for both, right on the top level.
> For ioctl, we'd have a new file_operation:
>
> long ioctl(struct file *, unsigned int, unsigned long, enum syscall_arch);
>
> I'm not saying this is easy, but I think it's possible and the result
> would be more obviously correct than what we have now.
No, it would not. Seriously, from time to time a bit of RTFS before grand
proposals turns out to be useful.
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