On Tue, Feb 26, 2019 at 11:56:57PM +0900, Akira Yokosawa wrote: > Hi Paul, > > On Tue, 26 Feb 2019 06:28:45 -0800, Paul E. McKenney wrote: > > On Tue, Feb 26, 2019 at 02:49:06PM +0100, Peter Zijlstra wrote: > >> On Tue, Feb 26, 2019 at 12:38:13PM +0100, Borislav Petkov wrote: > >>> On Tue, Feb 26, 2019 at 12:30:08PM +0100, Peter Zijlstra wrote: > >>>> When I used the argc variant, gcc-8 'works', but with s/argc/1/ it is > >>>> still broken. > >>> > >>> As requested on IRC: > >> > >> What I asked was if you could get your GCC developer friends to have a > >> look at this :-) > > > > Yes, this all is a bit on the insane side from a kernel viewpoint. > > But the paper you found does not impose this; it has instead been there > > for about 20 years, back before C and C++ admitted to the existence > > of concurrency. > > By "it", do you mean the concept of "pointer provenance"? > > I'm asking because the paper's header reads: > > "ISO/IEC JTC1/SC22/WG14 N2311, 2018-11-09" > > Just wanted to make sure. This paper introduces neither pointer provenance nor indeterminate-on-free, but rather proposes modification. These things have been around for a few decades. Thanx, Paul > Thanks, Akira > > > But of course compilers are getting more aggressive, > > and yes, some of the problems show up in single-threaded code. > > > > The usual response is "then cast the pointers to intptr_t!" but of > > course that breaks type checking. > > > > There is an effort to claw back the concurrency pieces, and I would > > be happy to run the resulting paper past you guys. > > > > I must confess to not being all that sympathetic to code that takes > > advantage of happenstance stack-frame layout. Is there some reason > > we need that? > > > > Thanx, Paul > > >
