linux-kernel - Re: Jump Label initialization

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:	Thu, 29 Sep 2011 14:04:54 +0200
From:	Jan Glauber <jang@...ux.vnet.ibm.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Jason Baron <jbaron@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Michael Ellerman <michael@...erman.id.au>,
	David Daney <ddaney@...iumnetworks.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: Jump Label initialization

On Wed, 2011-09-28 at 19:14 -0700, Jeremy Fitzhardinge wrote:
> Hi all,
> 
> I'm trying to use the jump label machinery as part of the pv ticketlock
> work I'm doing on x86.
> 
> The problem I'm having at the moment is that I do my spinlock setup in
> smp_prepare_boot_cpu(), which happens before jump_label_init() gets
> called, and so the latter goes and nops out all my enabled jump label key.
> 
> I'm experimenting at the moment with a patch to allow
> jump_label_enable() to be called fairly early, and have that be
> respected by jump_label_init().  I'm doing this by replacing
> arch_jump_label_poke_text_early() with
> arch_jump_label_transform_early(), which shares most of its code with
> its non-early variant, except that it expects to run in a pre-SMP
> environment.
> 
> Does this seem plausible? (I haven't tested it yet.)
> 
> The x86, mips and sparc patches are fairly simple; I forgot to look at
> powerpc, and I didn't fully investigate s390.

s390 does not have the early() variant since it didn't need it. On
pre-SMP we probably don't need stop_machine() so creating
arch_jump_label_transform_early() by leaving out stop_machine()
and patching the code directly should be fine.

--
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/