linux-kernel - Re: [RFC][PATCH 2/4 v4] ftrace/x86: Add save

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, 19 Jul 2012 19:04:23 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Frederic Weisbecker <fweisbec@...il.com>,
	yrl.pp-manager.tt@...achi.com
Subject: Re: [RFC][PATCH 2/4 v4] ftrace/x86: Add save_regs for i386 function
 calls

On Thu, 2012-07-19 at 15:53 -0700, H. Peter Anvin wrote:

> lea is not typically faster than add, but in the case of Atom, it is
> done in an earlier pipeline stage (AGU instead of ALU) which means lea
> is faster if its inputs are already available as address expressions and
> is consumed by address expressions; the goal is to avoid the ALU->AGU
> forwarding latency.

Well, the question is, which is faster:

	lea 8(%esp), %esp
	addl $8, %esp

Basically, all we want to do is add 8 to the stack pointer. And this is
for the x86_32 version of whatever hardware is in use.

-- Steve


--
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/