From owner-svn-src-head@freebsd.org  Mon Jan  8 11:08:46 2018
Return-Path: <owner-svn-src-head@freebsd.org>
Delivered-To: svn-src-head@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id BE7D4E64645;
 Mon,  8 Jan 2018 11:08:46 +0000 (UTC)
 (envelope-from andrew@FreeBSD.org)
Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org
 [IPv6:2610:1c1:1:606c::19:3])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "mxrelay.nyi.freebsd.org",
 Issuer "Let's Encrypt Authority X3" (verified OK))
 by mx1.freebsd.org (Postfix) with ESMTPS id 918A175E20;
 Mon,  8 Jan 2018 11:08:46 +0000 (UTC)
 (envelope-from andrew@FreeBSD.org)
Received: from repo.freebsd.org (repo.freebsd.org
 [IPv6:2610:1c1:1:6068::e6a:0])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id C2DA32ECFB;
 Mon,  8 Jan 2018 11:08:45 +0000 (UTC)
 (envelope-from andrew@FreeBSD.org)
Received: from repo.freebsd.org ([127.0.1.37])
 by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w08B8j0G014904;
 Mon, 8 Jan 2018 11:08:45 GMT (envelope-from andrew@FreeBSD.org)
Received: (from andrew@localhost)
 by repo.freebsd.org (8.15.2/8.15.2/Submit) id w08B8jN5014903;
 Mon, 8 Jan 2018 11:08:45 GMT (envelope-from andrew@FreeBSD.org)
Message-Id: <201801081108.w08B8jN5014903@repo.freebsd.org>
X-Authentication-Warning: repo.freebsd.org: andrew set sender to
 andrew@FreeBSD.org using -f
From: Andrew Turner <andrew@FreeBSD.org>
Date: Mon, 8 Jan 2018 11:08:45 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: svn commit: r327691 - head/sys/arm64/arm64
X-SVN-Group: head
X-SVN-Commit-Author: andrew
X-SVN-Commit-Paths: head/sys/arm64/arm64
X-SVN-Commit-Revision: 327691
X-SVN-Commit-Repository: base
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.25
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
 <svn-src-head.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head/>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 08 Jan 2018 11:08:46 -0000

Author: andrew
Date: Mon Jan  8 11:08:45 2018
New Revision: 327691
URL: https://svnweb.freebsd.org/changeset/base/327691

Log:
  Only install the new pagetable pointer into ttbr0_el1 when it differs from
  the existing value.
  
  MFC after:	1 week
  Sponsored by:	DARPA, AFRL

Modified:
  head/sys/arm64/arm64/pmap.c

Modified: head/sys/arm64/arm64/pmap.c
==============================================================================
--- head/sys/arm64/arm64/pmap.c	Mon Jan  8 10:23:31 2018	(r327690)
+++ head/sys/arm64/arm64/pmap.c	Mon Jan  8 11:08:45 2018	(r327691)
@@ -4677,17 +4677,20 @@ pmap_switch(struct thread *old, struct thread *new)
 	 * to a user process.
 	 */
 
-	__asm __volatile(
-	    /* Switch to the new pmap */
-	    "msr	ttbr0_el1, %0	\n"
-	    "isb			\n"
+	if (old == NULL ||
+	    old->td_proc->p_md.md_l0addr != new->td_proc->p_md.md_l0addr) {
+		__asm __volatile(
+		    /* Switch to the new pmap */
+		    "msr	ttbr0_el1, %0	\n"
+		    "isb			\n"
 
-	    /* Invalidate the TLB */
-	    "dsb	ishst		\n"
-	    "tlbi	vmalle1is	\n"
-	    "dsb	ish		\n"
-	    "isb			\n"
-	    : : "r"(new->td_proc->p_md.md_l0addr));
+		    /* Invalidate the TLB */
+		    "dsb	ishst		\n"
+		    "tlbi	vmalle1is	\n"
+		    "dsb	ish		\n"
+		    "isb			\n"
+		    : : "r"(new->td_proc->p_md.md_l0addr));
+	}
 
 	return (pcb);
 }