From owner-svn-src-all@FreeBSD.ORG Sat May 14 14:55:16 2011 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2652A1065670; Sat, 14 May 2011 14:55:16 +0000 (UTC) (envelope-from marcel@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 16B9E8FC0A; Sat, 14 May 2011 14:55:16 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.4/8.14.4) with ESMTP id p4EEtFTJ006712; Sat, 14 May 2011 14:55:15 GMT (envelope-from marcel@svn.freebsd.org) Received: (from marcel@localhost) by svn.freebsd.org (8.14.4/8.14.4/Submit) id p4EEtFIW006710; Sat, 14 May 2011 14:55:15 GMT (envelope-from marcel@svn.freebsd.org) Message-Id: <201105141455.p4EEtFIW006710@svn.freebsd.org> From: Marcel Moolenaar Date: Sat, 14 May 2011 14:55:15 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r221894 - head/sys/ia64/ia64 X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 14 May 2011 14:55:16 -0000 Author: marcel Date: Sat May 14 14:55:15 2011 New Revision: 221894 URL: http://svn.freebsd.org/changeset/base/221894 Log: Prefer switching the memory stack from user to kernel *before* switching the register stack. While the ordering doesn't matter, it creates an invariant not previously there: the memory stack pointer will always be larger than the register stack pointer. With this invariant in place, it's easier to add instrumentation code that detects a stack overflow because in such a scenario the memory stack pointer and register stack pointers have crossed each other. Aside: basic kernel operation needs about half the stack size (~16K) at most. We have plenty of head room on the kernel stack... Modified: head/sys/ia64/ia64/syscall.S Modified: head/sys/ia64/ia64/syscall.S ============================================================================== --- head/sys/ia64/ia64/syscall.S Sat May 14 14:47:19 2011 (r221893) +++ head/sys/ia64/ia64/syscall.S Sat May 14 14:55:15 2011 (r221894) @@ -239,21 +239,22 @@ ENTRY_NOPROFILE(epc_syscall, 8) ;; } { .mmi - mov ar.bspstore=r15 + mov r13=ar.k4 add r30=-SIZEOF_TRAPFRAME,r14 mov r20=sp ;; } { .mii - mov r13=ar.k4 + mov r21=ar.unat dep r30=0,r30,0,10 ;; add sp=-16,r30 ;; } { .mmi + mov ar.bspstore=r15 + ;; mov ar.rnat=r19 - mov r21=ar.unat add r31=8,r30 ;; }