linux-kernel - Re: [RFC] [PATCH 1/2 v2] x86: introduce int3-based instruction patching

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:	Wed, 10 Jul 2013 14:36:41 -0700
From:	"H. Peter Anvin" <hpa@...ux.intel.com>
To:	Jiri Kosina <jkosina@...e.cz>
CC:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Jason Baron <jbaron@...hat.com>,
	Borislav Petkov <bpetkov@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [RFC] [PATCH 1/2 v2] x86: introduce int3-based instruction patching

On 07/10/2013 02:31 PM, Jiri Kosina wrote:
> 
> If any CPU instruction execution would collide with the patching,
> it'd be trapped by the int3 breakpoint and redirected to the provided
> "handler" (which would typically mean just skipping over the patched
> region, acting as "nop" has been there, in case we are doing nop -> jump
> and jump -> nop transitions).
> 

I'm wondering if it would be easier/more general to just return to the
instruction.  The "more general" bit would allow this to be used for
other things, like alternatives, and perhaps eventually dynamic call
patching.

Returning to the instruction will, in effect, be a busy-wait for the
faulted CPU until the patch is complete; more or less what stop_machine
would do, but only for a CPU which actually strays into the affected region.

	-hpa


--
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/