Re: [PATCH 1/3] x86/entry: Clear extra registers beyond syscall arguments for 64bit kernels

From: Ingo Molnar
Date: Mon Feb 05 2018 - 13:33:18 EST



* Andy Lutomirski <luto@xxxxxxxxxx> wrote:

> [...] Clearing R10 is mostly useless in the syscall path because we'll just
> unconditionally reload it in do_syscall_64().

AFAICS do_syscall_64() doesn't touch R10 at all. So how does it reload R10?

In fact do_syscall_64() as a C function does not touch R10, R11, R12, R13, R14,
R15 - it passes their values through.

What am I missing?

Thanks,

Ingo