Re: [PATCH v2 4/5] pselect6: use __kernel_timespec

From: Deepa Dinamani
Date: Sat Sep 15 2018 - 14:37:59 EST

On Sat, Sep 15, 2018 at 8:28 AM Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Sat, Sep 15, 2018 at 7:09 AM Deepa Dinamani <deepa.kernel@xxxxxxxxx> wrote:
> > +#if defined(CONFIG_64BIT_TIME)
> > +
> > +COMPAT_SYSCALL_DEFINE6(pselect6_time64, int, n, compat_ulong_t __user *, inp,
> > + compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,
> > + struct __kernel_timespec __user *, tsp, void __user *, sig)
> I got a link error here since compat_sys_pselect6_time64 and
> compat_sys_ppoll_time64 are only defined when CONFIG_64BIT_TIME
> is set.
> I did not think we would select this symbol on arm64, is that a mistake
> on my side, or should the #ifdef check be removed?

But, this is a compat syscall.
When we introduced this CONFIG_64BIT_TIME we planned to use it for
compat syscalls also is my understanding.

config 64BIT_TIME
def_bool ARCH_HAS_64BIT_TIME
This should be selected by all architectures that need to support
new system calls with a 64-bit time_t. This is relevant on all 32-bit
architectures, and 64-bit architectures as part of compat syscall

This means it should be set on 64 bit architechtures also right?

If we don't have the #ifdef here then we have an entry point from
userspace defined and Thomas had pointed out that it was a security