linux-kernel - Re: cmpxchg and x86 flags output

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: <16406.1466612063@warthog.procyon.org.uk>
Date:	Wed, 22 Jun 2016 17:14:23 +0100
From:	David Howells <dhowells@...hat.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	dhowells@...hat.com, Peter Zijlstra <peterz@...radead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-arch <linux-arch@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: cmpxchg and x86 flags output

H. Peter Anvin <hpa@...or.com> wrote:

> So how do we make this move forward?

Getting my API additions in is relatively straightforward, I think.  The
whether-or-notness of the cmpxchg operation succeeding can be calculated by
comparing the original value read from memory with the value-to-be-replaced
inside the API function.

This can later be replaced with the boolean output from the CMPXCHG
instruction, the branch target from the LL/SC skipping or the result of the
intrinsics.

David