Re: [PATCH 20/20] objtool: Add Direction Flag validation

[Peter Zijlstra]

On Fri, Mar 08, 2019 at 03:56:02PM -0600, Josh Poimboeuf wrote:
> On Fri, Mar 08, 2019 at 10:33:43PM +0100, Peter Zijlstra wrote:
> > On Fri, Mar 08, 2019 at 03:16:03PM -0600, Josh Poimboeuf wrote:

> > > Can you elaborate on why (in the patch description)?  Did this actually
> > > find any occurrences?
> > 
> > Nope, didn't find anything. Also, all DF users are in asm so I didn't
> > really expect any. Having it escape would probably result in fairly
> > instant wreckage though.
> > 
> > DF=1 results in things like rep mov going _backwards_.
> 
> Ok, I wonder if we really need to add this then.

Well, Linus asked for it, and it was a fairly trivial add-on :-)