On Fri, Jul 14, 2023 at 04:26:45PM +0200, Arnd Bergmann wrote: > On Fri, Jul 14, 2023, at 15:39, Peter Zijlstra wrote: > > > > +++ b/include/linux/syscalls.h > > @@ -563,6 +563,9 @@ asmlinkage long sys_set_robust_list(stru > > asmlinkage long sys_futex_waitv(struct futex_waitv *waiters, > > unsigned int nr_futexes, unsigned int flags, > > struct __kernel_timespec __user *timeout, clockid_t clockid); > > + > > +asmlinkage long sys_futex_wake(void __user *uaddr, int nr, unsigned > > int flags, u64 mask); > > + > > You can't really use 'u64' arguments in portable syscalls, it causes > a couple of problems, both with defining the user space wrappers, > and with compat mode. > > Variants that would work include: > > - using 'unsigned long' instead of 'u64' > - passing 'mask' by reference, as in splice() > - passing the mask in two u32-bit arguments like in llseek() > > Not sure if any of the above work for you. Durr, I was hoping they'd use register pairs, but yeah I can see how that would be very hard to do in generic code. Hurmph.. using 2 u32s is unfortunate on 64bit, while unsigned long would limit 64bit futexes to 64bit machines (perhaps not too bad). Using unsigned long would help with the futex_wait() thing as well. I'll ponder things a bit. Obviously I only did build x86_64 ;-)
