linux-kernel - Re: blackfin - cmpxchg not atomic ?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20070720204507.GA15760@Krystal>
Date:	Fri, 20 Jul 2007 16:45:07 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Mike Frysinger <vapier.adi@...il.com>
Cc:	tonyko@...eo.ca, robin.getz@...log.com,
	linux-kernel@...r.kernel.org
Subject: Re: blackfin - cmpxchg not atomic ?

* Mike Frysinger (vapier.adi@...il.com) wrote:
> On 7/20/07, Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca> wrote:
> >I am currently passing through each architectures adding a
> >cmpxchg_local() to each system.h, and I notice that you disable
> >interrupts in your cmpxchg() implementation, why are you doing so ?
> 
> because Blackfin lacks any atomic instructions
> 
> >Also, does you assembly stub _really_ modify memory atomically ? If yes,
> >then there should be no need for disabling interrupts. Else, I see a
> >major problem with SMP.
> 
> that isnt the only problem with SMP on Blackfin
> 
> >I also don't like the comment in asm-blackfin/atomic.h :
> >
> > * Generally we do not concern about SMP BFIN systems, so we don't have
> > * to deal with that.
> >
> >I have seen on the blackfin website that you actually sell a board with
> >SMP. Why aren't you caring about it ?
> 
> just because a processor has more than one core does not make it SMP
> -mike

I see, thanks for the reply. Is there a particular reason for
implementing system.h/cmpxchg() in assembly rather that in plain C then?

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/