Re: [PATCH] sysv: linux: Pass 64-bit version of semctl syscall

[Alistair Francis <alistair23 at gmail dot com>]

On Fri, Jan 31, 2020 at 11:58 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Sat, Feb 1, 2020 at 12:59 AM Alistair Francis <alistair23@gmail.com> wrote:
> >
> > On Fri, Jan 31, 2020 at 1:54 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > >
> > > On Fri, Jan 31, 2020 at 6:11 PM Alistair Francis
> > > <alistair.francis@wdc.com> wrote:
> > > >
> > > > Adjust the semctl syscall to match what the kernel expects. That is pass
> > > > a version with a *_high version of sem_otime and sem_ctime in the order
> > > > that the kernel expects.
> > >
> > > > +# ifdef __SEMID_DS_HIGH
> > > > +#  if defined (__SEMID_DS_HIGH_END)
> > > ...
> > > > +#  elif defined (__SEMID_DS_HIGH_SWAP)
> > >
> > > The three new macros you check for here directly correspond to the
> > > possible combinations of the existing __SEM_PAD_AFTER_TIME
> > > and __SEM_PAD_BEFORE_TIME macros, right?
> >
> > Hey Arnd,
> >
> > I think you are asking why we don't just use the existing macros
> > instead of adding more (and keep the core logic as is). Besides the
> > naming being confusing then, they two types don't line up. For
> > example:
> >
> > PowerPC has this:
> >
> >  #define __SEM_PAD_AFTER_TIME 0
> >  #define __SEM_PAD_BEFORE_TIME (__TIMESIZE == 32)
> > +#define __SEMID_DS_HIGH (__WORDSIZE == 32)
> > +#define __SEMID_DS_HIGH_SWAP (__WORDSIZE == 32)
> >
> > while HPPA has this:
> >
> >  #define __SEM_PAD_AFTER_TIME 0
> >  #define __SEM_PAD_BEFORE_TIME (__TIMESIZE == 32)
> > +#define __SEMID_DS_HIGH (__WORDSIZE == 32)
> >
> > They have different __SEMID_DS macros, but the same __SEM_PAD macros.
>
> If they don't line up, that probably means that one of them is wrong ;-)

Ha, ok I'll double check and update it.

Even still, I would rather not use the existing macros as they use
__TIMESIZE == 32 and the new ones are using __WORDSIZE == 32. We could
of course just have a RV32 override that fixes it for RV32, but then
we need another override.

The main reason not to is that I think it would be confusing to
overload the macro like that and I don't see a disadvantage in having
a new macro. It makes what is going on (which is already somewhat
confusing) more clear.

If everyone really disagrees I can use the existing ones.

Alistair

>
> It looks like the HPPA version to also define __SEMID_DS_HIGH_SWAP.
>
>        Arnd