[PATCH v2 1/1] aarch64: clear ZA state of SME before clone and clone3 syscalls

[Yury Khrustalev]

On Mon, Jun 16, 2025 at 03:56:10PM +0200, Florian Weimer wrote:
> * Yury Khrustalev:
> 
> > Call __libc_arm_za_disable before syscall to clear ZA state of SME for the
> > clone and clone3 syscalls.
> 
> These system calls are frequently called through general syscall wrapper
> function.  Doesn't that have to be fixed as well?

As far as I know, there isn't any use of syscall(__NR_clone, ...) or syscall
(__NR_clone3, ...) in the Glibc (or any SVC in assembly that would use either
of these syscall numbers).

Userspace should ideally use the clone() function that is part of the Glibc API.
In case of clone3() there is no such public function.

Any direct syscall is regarded as sufficiently low level, and we presume that
those who do that already know what they are doing and they would have to do
all the required ABI-related preparations.

I think it would be impractical to modify syscall() wrapper to account for any
specifics of clone and clone3 syscalls also given that it's AArch64 specific.