[RFC PATCH v1 11/28] riscv: Implementing "PROT_SHADOWSTACK" on riscv

[Edgecombe, Rick P]

On Wed, 2024-01-24 at 22:21 -0800, debug at rivosinc.com wrote:
> +       /*
> +        * PROT_SHADOWSTACK is a kernel only protection flag on risc-
> v.
> +        * mmap doesn't expect PROT_SHADOWSTACK to be set by user
> space.
> +        * User space can rely on `map_shadow_stack` syscall to
> create
> +        * shadow stack pages.
> +        */
> +       if (unlikely(prot & PROT_SHADOWSTACK))
> +               return -EINVAL;

Are you sure you need PROT_SHADOWSTACK? Since you are passing
VM_SHADOW_STACK into do_mmap() directly.