From owner-svn-src-stable@FreeBSD.ORG  Sun Oct 31 08:02:48 2010
Return-Path: <owner-svn-src-stable@FreeBSD.ORG>
Delivered-To: svn-src-stable@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 159231065698;
	Sun, 31 Oct 2010 08:02:48 +0000 (UTC)
	(envelope-from nyan@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id 03DC48FC08;
	Sun, 31 Oct 2010 08:02:48 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
	by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id o9V82lhK058544;
	Sun, 31 Oct 2010 08:02:47 GMT (envelope-from nyan@svn.freebsd.org)
Received: (from nyan@localhost)
	by svn.freebsd.org (8.14.3/8.14.3/Submit) id o9V82lBO058542;
	Sun, 31 Oct 2010 08:02:47 GMT (envelope-from nyan@svn.freebsd.org)
Message-Id: <201010310802.o9V82lBO058542@svn.freebsd.org>
From: Takahashi Yoshihiro <nyan@FreeBSD.org>
Date: Sun, 31 Oct 2010 08:02:47 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
	svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org
X-SVN-Group: stable-8
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc: 
Subject: svn commit: r214589 - stable/8/sys/pc98/pc98
X-BeenThere: svn-src-stable@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: SVN commit messages for all the -stable branches of the src tree
	<svn-src-stable.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-stable>, 
	<mailto:svn-src-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-stable>
List-Post: <mailto:svn-src-stable@freebsd.org>
List-Help: <mailto:svn-src-stable-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-stable>,
	<mailto:svn-src-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 31 Oct 2010 08:02:48 -0000

Author: nyan
Date: Sun Oct 31 08:02:47 2010
New Revision: 214589
URL: http://svn.freebsd.org/changeset/base/214589

Log:
  MFC: revision 208632
  
    Clarify a potential issue in get_fpcontext() use.

Modified:
  stable/8/sys/pc98/pc98/machdep.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)
  stable/8/sys/dev/xen/xenpci/   (props changed)

Modified: stable/8/sys/pc98/pc98/machdep.c
==============================================================================
--- stable/8/sys/pc98/pc98/machdep.c	Sun Oct 31 07:57:05 2010	(r214588)
+++ stable/8/sys/pc98/pc98/machdep.c	Sun Oct 31 08:02:47 2010	(r214589)
@@ -561,6 +561,13 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, 
 	sf.sf_uc.uc_mcontext.mc_gs = rgs();
 	bcopy(regs, &sf.sf_uc.uc_mcontext.mc_fs, sizeof(*regs));
 	sf.sf_uc.uc_mcontext.mc_len = sizeof(sf.sf_uc.uc_mcontext); /* magic */
+
+	/*
+	 * The get_fpcontext() call must be placed before assignments
+	 * to mc_fsbase and mc_gsbase due to the alignment-override
+	 * code in get_fpcontext() that possibly clobbers 12 bytes of
+	 * mcontext after mc_fpstate.
+	 */
 	get_fpcontext(td, &sf.sf_uc.uc_mcontext);
 	fpstate_drop(td);
 	/*
@@ -2453,6 +2460,13 @@ get_mcontext(struct thread *td, mcontext
 	mcp->mc_esp = tp->tf_esp;
 	mcp->mc_ss = tp->tf_ss;
 	mcp->mc_len = sizeof(*mcp);
+
+	/*
+	 * The get_fpcontext() call must be placed before assignments
+	 * to mc_fsbase and mc_gsbase due to the alignment-override
+	 * code in get_fpcontext() that possibly clobbers 12 bytes of
+	 * mcontext after mc_fpstate.
+	 */
 	get_fpcontext(td, mcp);
 	sdp = &td->td_pcb->pcb_fsd;
 	mcp->mc_fsbase = sdp->sd_hibase << 24 | sdp->sd_lobase;