Re: [PATCH v2 4/6] x86: Rewrite switch_to() code

Josh Poimboeuf
2016-06-20T15:45:25Z

On Sat, Jun 18, 2016 at 04:56:16PM -0400, Brian Gerst wrote:
> Move the low-level context switch code to an out-of-line asm stub instead of
> using complex inline asm. This allows constructing a new stack frame for the
> child process to make it seamlessly flow to ret_from_fork without an extra
> test and branch in __switch_to(). It also improves code generation for
> __schedule() by using the C calling convention instead of clobbering all
> registers.
>
> Signed-off-by: Brian Gerst <brgerst@gmail.com>

You can also remove the STACK_FRAME_NON_STANDARD annotation for
__schedule() in kernel/sched/core.c since it no longer produces an
objtool warning.

Otherwise it looks great:

Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>

--
Josh