Re: [PATCH 18/20] objtool: Add UACCESS validation

[Peter Zijlstra]

On Fri, Mar 08, 2019 at 09:07:03AM -0600, Josh Poimboeuf wrote:
> On Thu, Mar 07, 2019 at 09:40:21PM +0100, Peter Zijlstra wrote:
> > On Thu, Mar 07, 2019 at 09:23:19PM +0100, Peter Zijlstra wrote:
> > > On Thu, Mar 07, 2019 at 07:48:13PM +0100, Peter Zijlstra wrote:
> > > > Another thing I need to look at is why objtool only found memset_orig
> > > > (from __memset) but not memset_erms, which if I read the code right, is
> > > > a possible alternative there.
> > > 
> > > Turns out we only look for sibling calls in the original instruction
> > > stream, not in any alternatives; which in general seems like a fair
> > > enough assumption.
> > 
> > And while I'm looking at memset_64.S, why are memset_erms and
> > memset_orig global functions? At the very least they should be local,
> > and ideally not even functions.
> 
> I think the only benefit is that they would show up better on stack
> traces, but that could also be solved by just making them local labels
> inside memset.  Which is what I think they should be.

Boris wanted to use alternative_call_2, just like copy_user_generic().
Which makes more sense to me still.