Re: [PATCH] posix-clock: Explicitly handle compat ioctls

[Richard Cochran]

On Wed, Jan 22, 2025 at 08:30:51AM +0100, Arnd Bergmann wrote:
> On Tue, Jan 21, 2025, at 23:41, Thomas Weißschuh wrote:
> > Pointer arguments passed to ioctls need to pass through compat_ptr() to
> > work correctly on s390; as explained in Documentation/driver-api/ioctl.rst.
> > Plumb the compat_ioctl callback through 'struct posix_clock_operations'
> > and handle the different ioctls cmds in the new ptp_compat_ioctl().
> >
> > Using compat_ptr_ioctl is not possible.
> > For the commands PTP_ENABLE_PPS/PTP_ENABLE_PPS2 on s390
> > it would corrupt the argument 0x80000000, aka BIT(31) to zero.
> >
> > Fixes: 0606f422b453 ("posix clocks: Introduce dynamic clocks")
> > Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
> 
> This looks correct to me,

I'm not familiar with s390, but I can remember that the compat ioctl
was nixed during review.

   https://lore.kernel.org/lkml/201012161716.42520.arnd@xxxxxxxx/

   https://lore.kernel.org/lkml/alpine.LFD.2.00.1012161939340.12146@localhost6.localdomain6/

Can you explain what changed or what was missed?

Thanks,
Richard