linux-kernel - Re: mips octeon memory model questions

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]

Date:	Tue, 4 Feb 2014 20:39:41 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	David Daney <ddaney@...iumnetworks.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	linux-mips <linux-mips@...ux-mips.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Will Deacon <will.deacon@....com>
Subject: Re: mips octeon memory model questions

On Tue, Feb 04, 2014 at 11:16:58AM -0800, Linus Torvalds wrote:
> On Tue, Feb 4, 2014 at 11:05 AM, Peter Zijlstra
> >
> >> So writes move down, not up.
> >
> > Right, but the ll-sc store might move down over a later store.
> 
> Unlikely. The thing is, in order for the sc to succeed, it has to
> already have hit the cache coherency domain (or at least reserved it -
> ie maybe the value is not actually *in* the cache, but the sc needs to
> have gotten exclusive access to the cacheline).
> 
> So just how do you expect a later store (that is *after* the
> conditional branch that tests the result of the sc) to move up before
> it?

Ah, I completely overlooked the control dependency to the subsequent
store.

Yes, given that this makes sense.
--
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/