From owner-svn-src-all@FreeBSD.ORG  Sat May 29 03:06:56 2010
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
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 E64DA1065670;
	Sat, 29 May 2010 03:06:56 +0000 (UTC)
	(envelope-from nyan@FreeBSD.org)
Received: from svn.freebsd.org (unknown [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id D52368FC1B;
	Sat, 29 May 2010 03:06:56 +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 o4T36uff087143;
	Sat, 29 May 2010 03:06:56 GMT (envelope-from nyan@svn.freebsd.org)
Received: (from nyan@localhost)
	by svn.freebsd.org (8.14.3/8.14.3/Submit) id o4T36uog087141;
	Sat, 29 May 2010 03:06:56 GMT (envelope-from nyan@svn.freebsd.org)
Message-Id: <201005290306.o4T36uog087141@svn.freebsd.org>
From: Takahashi Yoshihiro <nyan@FreeBSD.org>
Date: Sat, 29 May 2010 03:06:56 +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: r208632 - head/sys/pc98/pc98
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 \(except for &quot;
	user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 29 May 2010 03:06:57 -0000

Author: nyan
Date: Sat May 29 03:06:56 2010
New Revision: 208632
URL: http://svn.freebsd.org/changeset/base/208632

Log:
  MFi386: revision 208604
  
    Clarify a potential issue in get_fpcontext() use.

Modified:
  head/sys/pc98/pc98/machdep.c

Modified: head/sys/pc98/pc98/machdep.c
==============================================================================
--- head/sys/pc98/pc98/machdep.c	Sat May 29 02:14:05 2010	(r208631)
+++ head/sys/pc98/pc98/machdep.c	Sat May 29 03:06:56 2010	(r208632)
@@ -563,6 +563,13 @@ 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);
 	/*
@@ -2455,6 +2462,13 @@ 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_gsd;
 	mcp->mc_fsbase = sdp->sd_hibase << 24 | sdp->sd_lobase;