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,
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
> +#ifdef CONFIG_COMPAT
> +long ptp_compat_ioctl(struct posix_clock_context *pccontext, unsigned
> int cmd,
> + unsigned long arg)
> +{
> + switch (cmd) {
> + case PTP_ENABLE_PPS:
> + case PTP_ENABLE_PPS2:
> + /* These take in scalar arg, do not convert */
> + break;
I was confused a bit here because the PTP_ENABLE_PPS and
PTP_ENABLE_PPS2 definitions use _IOW(..., int), suggesting
that the argument is passed through a pointer, when the code
uses the 'arg' as a integer instead. Not your fault of course
but it might help to explain this in the comment.
Arnd
