linux-kernel - Re: [PATCH 4/6] trace: trace syscall in its handler not from ptrace handler

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: <4F74E6C2.8050003@zytor.com>
Date:	Thu, 29 Mar 2012 15:48:34 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	David Sharp <dhsharp@...gle.com>
CC:	Vaibhav Nagarnaik <vnagarnaik@...gle.com>,
	Ingo Molnar <mingo@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Justin Teravest <teravest@...gle.com>,
	Laurent Chavey <chavey@...gle.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] trace: trace syscall in its handler not from ptrace
 handler

On 03/29/2012 03:44 PM, David Sharp wrote:
>>
>> ANY increase to the fastpath is unacceptable, period.
> 
> I think the last 4 ns would probably be eliminated if we could figure
> out how to call the inline function trace_sys_enter directly instead
> of through the out-of-line wrapper we had to add to work around the
> preprocessor magic.

I already told you how to do it... override the system call table entry.
 There is a nice, juicy FUNCTION POINTER that we indirect through.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
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/