[OE-core] pseudo: host user contamination

[Andre McCurdy]

On Sat, Mar 24, 2018 at 12:50 PM, Seebs <seebs at seebs.net> wrote:
>
> pseudo's call sequence:
>         various_setup()
>         real_syscall() // sets a3
>         other system calls // also set a3
>         return

You don't need to know that the kernel returns a result in any
particular register. The libc syscall() internal implementation will
take care of collecting the result from the kernel and returning it
via the normal function call ABI. Therefore pseudo's call sequence
becomes something like:

        various_setup()
        temp = real_syscall()
        other system calls
        return temp