sigprocmask is a neat solution, but requires a syscall. Would it be theoretically possible to share the signal mask between the userspace and the kernel in no-c

sigprocmask is a neat solution, but requires a syscall. Would it be theoretically possible to share the signal mask between the userspace and the kernel in no-cost way? I'm thinking vDSO style, mmaped var. This could have big implications, for example most classic coroutine implementations using setjmp do some procmask dance.