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@vger.kernel.org Signed-off-by: Thomas Weißschuh linux@weissschuh.net
This looks correct to me,
Reviewed-by: Arnd Bergmann arnd@arndb.de
+#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