[lkml]   [2020]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag
On Sat, Sep 19, 2020 at 4:24 PM Al Viro <> wrote:
> On Sat, Sep 19, 2020 at 03:53:40PM -0700, Andy Lutomirski wrote:
> > > It would not be a win - most of the syscalls don't give a damn
> > > about 32bit vs. 64bit...
> >
> > Any reasonable implementation would optimize it out for syscalls that don’t care. Or it could be explicit:
> >
> 1) what would that look like?

In effect, it would work like this:

/* Arch-specific, but there's a generic case for sane architectures. */
enum syscall_arch {

args are the args here, and arch is the arch.

> 2) have you counted the syscalls that do and do not need that?


> 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.

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.

 \ /
  Last update: 2020-09-20 02:15    [W:0.130 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site