[PATCH v2 5/7] arm64/efi: Use a semaphore to protect the EFI stack and FP/SIMD state

[Peter Zijlstra]

On Fri, Sep 05, 2025 at 03:30:41PM +0200, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb at kernel.org>
> 
> Replace the spinlock in the arm64 glue code with a semaphore, so that
> the CPU can preempted while running the EFI runtime service.

Gotta ask, why a semaphore and not a mutex?