Re: [RFC PATCH 06/10] x86/entry: add CFI hint undwarf annotations

From: Josh Poimboeuf
Date: Thu Jun 01 2017 - 10:29:04 EST


On Thu, Jun 01, 2017 at 09:23:58AM -0500, Josh Poimboeuf wrote:
> On Thu, Jun 01, 2017 at 07:03:18AM -0700, Andy Lutomirski wrote:
> > On Wed, May 31, 2017 at 10:44 PM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> > Just to make sure I understand this, if we unwind from...
> >
> > > @@ -112,6 +114,7 @@ For 32-bit we have the following conventions - kernel is built with
> > > movq %rdx, 12*8+\offset(%rsp)
> > > movq %rsi, 13*8+\offset(%rsp)
> >
> > ...here..., will objtool think that rdx and rsi (etc) still live in
> > their respective regs, or will it find them in the on-stack data given
> > by CFI_REGS? If the former, how does undwarf deal with the
> > corresponding pops?
>
> It will find them in their respective registers, which is fine because
> they haven't been clobbered yet.

Sorry, I hit send too soon. Which pops are you referring to?

--
Josh