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

[Josh Poimboeuf]

On Sun, Mar 10, 2019 at 02:13:31PM +0100, Peter Zijlstra wrote:
> 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 :-)

If it doesn't matter much either way, I'd rather err on the side of less
code.  Your call though.

-- 
Josh