Re: [PATCH 2/2] arch: add pidfd and io_uring syscalls everywhere

Arnd Bergmann
2019-03-26T08:40:57Z

On Mon, Mar 25, 2019 at 6:37 PM Paul Burton <paul.burton@mips.com> wrote:
> On Mon, Mar 25, 2019 at 03:47:37PM +0100, Arnd Bergmann wrote:
> > Add the io_uring and pidfd_send_signal system calls to all architectures.
> >
> > These system calls are designed to handle both native and compat tasks,
> > so all entries are the same across architectures, only arm-compat and
> > the generic tale still use an old format.
> >
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >%
> > diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
> > index c85502e67b44..c4a49f7d57bb 100644
> > --- a/arch/mips/kernel/syscalls/syscall_n64.tbl
> > +++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
> > @@ -338,3 +338,7 @@
> > 327 n64 rseq sys_rseq
> > 328 n64 io_pgetevents sys_io_pgetevents
> > # 329 through 423 are reserved to sync up with other architectures
> > +424 common pidfd_send_signal sys_pidfd_send_signal
> > +425 common io_uring_setup sys_io_uring_setup
> > +426 common io_uring_enter sys_io_uring_enter
> > +427 common io_uring_register sys_io_uring_register
>
> Shouldn't these declare the ABI as "n64"?
>
> I don't see anywhere that it would actually change the generated code,
> but a comment at the top of the file says that every entry should use
> "n64" and so far they all do. Did you have something else in mind here?

You are right, the use of 'common' here is unintentional but harmless,
and I should have used 'n64' here.

We may decide to do things differently in the future, i.e. we could
have just a single global file for newly added system calls once
it turns out that the tables are consistent across all architectures,
but I'd probably go on with the separate identical entries for a bit
before changing that.

Arnd