linux-kernel - Re: [PATCH 03/10] jump label v11: base patch

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, 21 Sep 2010 11:58:56 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	Jason Baron <jbaron@...hat.com>, linux-kernel@...r.kernel.org,
	mingo@...e.hu, mathieu.desnoyers@...ymtl.ca, tglx@...utronix.de,
	rostedt@...dmis.org, andi@...stfloor.org, roland@...hat.com,
	rth@...hat.com, mhiramat@...hat.com, fweisbec@...il.com,
	avi@...hat.com, davem@...emloft.net, vgoyal@...hat.com,
	sam@...nborg.org, tony@...eyournoodle.com
Subject: Re: [PATCH 03/10] jump label v11: base patch

On 09/21/2010 11:55 AM, Konrad Rzeszutek Wilk wrote:
>>> +early_initcall(init_jump_label);
>>
>> Is there any danger of not patching the instructions with NOPs before
>> early_initcall is called? I guess for your uses (tracing) there won't.
>> And even if there are not patched it will just call the function.
> 
> Ah, nevermind - if you don't patch the addresses which are in
> _jump_label section, the untouched code will just do far jump (jmpq)
> to right after the macro, which is ok.

Technical point of order: jmpq is *NOT* a far jump.  A far jump (called
ljmp in gas) is a completely different x86 instruction with *very*
different semantics.

	-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/