Re: [PATCH] x86/retpoline/entry: Disable the entire SYSCALL64 fast path with retpolines on

[Linus Torvalds]

On Fri, Jan 26, 2018 at 10:07 AM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> Umm...  What about other architectures?  Or do you want SYSCALL_DEFINE...
> to be per-arch?  I wonder how much would that "go through pt_regs" hurt
> on something like sparc...

No, but I just talked to Will Deacon about register clearing on entry,
and so I suspect that arm64 might want something similar too.

So I think some opt-in for letting architectures add their own
function would be good. Because it wouldn't be all architectures, but
it probably _would_ be more than just x86.

You need to add architecture-specific "load argX from ptregs" macros anyway.

             Linus