Re: [PATCH 1/5] objtool: Change REG_SP_INDIRECT

[Josh Poimboeuf]

On Wed, Feb 03, 2021 at 03:49:02PM +0100, Peter Zijlstra wrote:
> On Wed, Feb 03, 2021 at 08:42:15AM -0600, Josh Poimboeuf wrote:
> > On Wed, Feb 03, 2021 at 01:02:23PM +0100, Peter Zijlstra wrote:
> > > Currently REG_SP_INDIRECT is unused but means (%rsp + offset),
> > > change it to mean (%rsp) + offset.
> > > 
> > > This is somewhat unfortunate, since REG_BP_INDIRECT is used (by DRAP)
> > > and thus needs to retain the current (%rbp + offset).
> > 
> > Offset is going to be zero, should it not work either way?
> 
> For DRAP? I couldn't tell in a hurry. I'm ever quite clear on how DRAP
> works. Some day, when I figure it out, i'll write a comment.
> 
> Anyway, if it's always 0 for DRAP, then yes, I'll change both.

No, what I meant to say is that UNWIND_HINT_INDIRECT is used with no
arguments, which means that sp_offset is always zero.

-- 
Josh