linux-kernel - Re: [RFC/PATCH] doc: volatile considered evil

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: <4640F9C4.8050804@goop.org>
Date:	Tue, 08 May 2007 15:29:24 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	David Rientjes <rientjes@...gle.com>
CC:	Randy Dunlap <randy.dunlap@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Paul Sokolovsky <pmiscml@...il.com>,
	linux-kernel@...r.kernel.org, Andi Kleen <ak@...e.de>
Subject: Re: [RFC/PATCH] doc: volatile considered evil

David Rientjes wrote:
> It is analogous with a sequence point for ia64.  But, as you mentioned, it 
> is ia64 specific so your comment about "asm volatile" constructs not being 
> reordered is always appropriate outside of ia64 specific code but may not 
> apply to ia64 if we ever compiled with -mvolatile-asm-stop.  If we do not
> compile with that option, the behavior is unspecified.  I don't think 
> we'll be adding -mvolatile-asm-stop support any time soon so your warning 
> certainly is appropriate for all code at this time.
>   

Sounds like it's referring to micro-architectural reordering, which is
distinct from compiler reordering.  In other words, even if you
specified "-mvolatile-asm-stop" I would assume that the compiler could
still reorder the asm statements.  Am I right, or should I read more
into the manual description than it actually says?

    J
-
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/