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SubjectRe: [PATCH v10 04/11] x86/entry/64: Adapt assembly for PIE support
On Thu, Dec 5, 2019 at 1:04 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Dec 04, 2019 at 04:09:41PM -0800, Thomas Garnier wrote:
>
> > @@ -1625,7 +1627,11 @@ first_nmi:
> > addq $8, (%rsp) /* Fix up RSP */
> > pushfq /* RFLAGS */
> > pushq $__KERNEL_CS /* CS */
> > - pushq $1f /* RIP */
> > + pushq $0 /* Future return address */
>
> We're building an IRET frame, the IRET frame does not have a 'future
> return address' field.

I assumed that's the target RIP after iretq.

>
> > + pushq %rdx /* Save RAX */
>
> fail..

Yes, sorry. I was asked to switch from RAX to RDX and missed the comment.

>
> > + leaq 1f(%rip), %rdx /* RIP */
>
> nonsensical comment

That was the same comment from the push $1f that I changed.

>
> > + movq %rdx, 8(%rsp) /* Put 1f on return address */
> > + popq %rdx /* Restore RAX */
>
> fail..

I will change in next iteration.

>
> > iretq /* continues at repeat_nmi below */
> > UNWIND_HINT_IRET_REGS
> > 1:
> > --
> > 2.24.0.393.g34dc348eaf-goog
> >

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