Re: [PATCH 22/24] x86/entry: Implement and use do_paranoid_entry() and paranoid_exit()

[Lai Jiangshan]

On 2021/9/2 18:33, Peter Zijlstra wrote:
> On Wed, Sep 01, 2021 at 01:50:23AM +0800, Lai Jiangshan wrote:
>
> > +	call	do_paranoid_entry
> >   	ret
>
> That's normally spelled like:
>
> 	jmp do_paranoid_entry
>
> But the same comment as for error_entry but more; pretty much all that's
> left in asm is things like:
>
>
> 	call paranoid_entry;
>
> 	# setup args
> 	call \cfunc
>
> 	call paranoid_exit
>
> which seems like prime material to also pull into C to avoid the
> back-and-forth thing. In fact, why can't you call paranoid_entry/exit
> from \cfunc itself? The IDT macros should be able to help.

Oh, #VC will need to switch stack.  I think we need ASM code to switch
stack since the original stack need to be "free" for next #VC.