[PATCH] linux: Add mseal syscall support

[Collin Funk]

Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:

> +      if (errno == ENOSYS)
> +        FAIL_UNSUPPORTED
> +          ("kernel does not support memory protection keys");
> +      if (errno == EINVAL)
> +        FAIL_UNSUPPORTED
> +          ("CPU does not support memory protection keys: %m");

Do any other syscalls fail with different errno's depending on if the
kernel or the CPU do not support them? I feel like it is better to use
ENOSYS in both cases, but maybe I am missing something.

Also, for formatting long lines like this I think the following looks
better:

      FAIL_UNSUPPORTED ("CPU does not support "
                        "memory protection keys: %m");

Collin