Hi Florian, On Thu, Nov 24, 2022 at 06:25:39AM +0100, Florian Weimer wrote: > * Jason A. Donenfeld: > > > Hi Florian, > > > > On Wed, Nov 23, 2022 at 11:46:58AM +0100, Florian Weimer wrote: > >> * Jason A. Donenfeld: > >> > >> > + * The vgetrandom() function in userspace requires an opaque state, which this > >> > + * function provides to userspace, by mapping a certain number of special pages > >> > + * into the calling process. It takes a hint as to the number of opaque states > >> > + * desired, and returns the number of opaque states actually allocated, the > >> > + * size of each one in bytes, and the address of the first state. > >> > + */ > >> > +SYSCALL_DEFINE3(vgetrandom_alloc, unsigned long __user *, num, > >> > + unsigned long __user *, size_per_each, unsigned int, flags) > >> > >> I think you should make this __u64, so that you get a consistent > >> userspace interface on all architectures, without the need for compat > >> system calls. > > > > That would be quite unconventional. Most syscalls that take lengths do > > so with the native register size (`unsigned long`, `size_t`), rather > > than u64. If you can point to a recent trend away from this by > > indicating some commits that added new syscalls with u64, I'd be happy > > to be shown otherwise. But AFAIK, that's not the way it's done. > > See clone3 and struct clone_args. The struct is one thing. But actually, clone3 takes a `size_t`: SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size) I take from this that I too should use `size_t` rather than `unsigned long.` And it doesn't seem like there's any compat clone3. Jason