Date: Wed, 2 Nov 2016 15:55:08 +0900 From: AKASHI Takahiro <takahiro.akashi@...aro.org> To: kernel-hardening@...ts.openwall.com Cc: Colin Vidal <colin@...dal.org>, "keescook@...omium.org" <keescook@...omium.org>, "arnd@...db.de" <arnd@...db.de>, "tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com" <mingo@...hat.com>, "Anvin, H Peter" <h.peter.anvin@...el.com>, Hans Liljestrand <ishkamiel@...il.com>, David Windsor <dwindsor@...il.com> Subject: Re: [RFC v3 PATCH 01/13] Add architecture independent hardened atomic base On Tue, Nov 01, 2016 at 12:15:25PM +0000, Reshetova, Elena wrote: > >Hi (again :-)) Elena, Hans, > > > diff --git a/include/linux/atomic.h b/include/linux/atomic.h > <snip> > > +#ifndef atomic_cmpxchg_wrap > > +#define atomic_cmpxchg_wrap(...) \ > > + __atomic_op_fence(atomic_cmpxchg_wrap, __VA_ARGS__) #endif > > #endif /* atomic_cmpxchg_relaxed */ > > > > >I have a problem here. With ARMv7 (without any of my patches), I have a > >implicit declaration of atomic_cmpxchg_wrap. Perhaps something like > > > #ifndef atomic_cmpxchg_wrap_relaxed > > #define atomic_cmpxchg_wrap_relaxed atomic_cmpxchg_wrap > > >is missing? I didn't follow the recent changes of that part, so I am > >not quite sure... > > >Thanks! > > >Colin > > >In file included from ./include/linux/spinlock.h:406:0, > from ./include/linux/seqlock.h:35, > from ./include/linux/time.h:5, > from ./include/linux/stat.h:18, > from ./include/linux/module.h:10, > from net/ipv4/route.c:67: > >net/ipv4/route.c: In function ‘ip_idents_reserve’: > >./include/linux/atomic.h:459:20: error: implicit declaration of function ‘atomic_cmpxchg_wrap_relaxed’ [-Werror=implicit-function-declaration] > __atomic_op_fence(atomic_cmpxchg_wrap, __VA_ARGS__) > ^ > >./include/linux/atomic.h:62:9: note: in definition of macro ‘__atomic_op_fence’ > > typeof(op##_relaxed(args)) __ret; \ > ^~ > >net/ipv4/route.c:488:11: note: in expansion of macro ‘atomic_cmpxchg_wrap’ > > } while (atomic_cmpxchg_wrap(p_id, old, new) != old); > > Oh, I think this is because we don't have atomic_cmpxchg_wrap_relaxed defined neither atomic_xchg_wrap_relaxed. Wonder why this doesn't show up on x86, I did many builds without our x86 changes to verify. > Hans could you please handle this change today to unblock Colin? > > Actually this brings us to the fact that we tried to stay away from various relaxed/acquire/release functions (in providing default wrap implementations), but it seems that they are also needed... This is just a reminder. There is a potential inconsistency in naming: atomic_xx_wrap_relaxed vs. atomic_xx_relaxed_wrap See: http://www.openwall.com/lists/kernel-hardening/2016/10/25/7 -Takahiro AKASHI > Sigh.. This grows bigger and bigger every day. I hope atomic doesn't plan to come with more functions in the nearest future :) > > Kees, what is your opinion on relaxed/acquire/release coverage? > > Best Regards, > Elena.
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