From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750777AbWFXBhZ (ORCPT ); Fri, 23 Jun 2006 21:37:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750783AbWFXBhZ (ORCPT ); Fri, 23 Jun 2006 21:37:25 -0400 Received: from nz-out-0102.google.com ([64.233.162.203]:28549 "EHLO nz-out-0102.google.com") by vger.kernel.org with ESMTP id S1750777AbWFXBhZ (ORCPT ); Fri, 23 Jun 2006 21:37:25 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=XTW+jnBWBZSvLq2rh2oOrRMEZEt3FnEGUrcUOmt5G30OKbZSH5OprT4LBeUOjYfI8GdDu8hmYAsz+reugxbTZhoSDrQLidwmUEwRdNFqePxaUaG3cNBe91vmOqH2V9+cYILEWWKutYN/ES7N042QAhfrGaugIFDyiFXofuhGYo8= Message-ID: <787b0d920606231837k5d57da8ct5c511def6c035176@mail.gmail.com> Date: Fri, 23 Jun 2006 21:37:24 -0400 From: "Albert Cahalan" To: linux-kernel@vger.kernel.org, "Linus Torvalds" , 76306.1226@compuserve.com, ak@muc.de, akpm@osdl.org Subject: i386 ABI and the stack MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I just saw git commit 21528454f6dd18231ae20102f98aa8f51b6ec1b9 go in with this: + * Accessing the stack below %esp is always a bug. + * The large cushion allows instructions like enter + * and pusha to work. ("enter $65535,$31" pushes + * 32 pointers and then decrements %esp by 65535.) Exactly how is an access below %esp a bug if we just added support? It looks like we now have a 65664-byte red zone on i386, and probably on x86-64 once the matching patch goes in. (the space reserved by signal handlers may differ, though perhaps it should not) This is water under the bridge anyway, because of gcc 2.xx.x bugs. It seems that we're throwing away performance if we discourage the compiler from taking advantage of this area to optimize leaf functions and perhaps improve instruction scheduling.