From patchwork Tue May 14 12:21:29 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 10942855 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E588C1398 for ; Tue, 14 May 2019 12:23:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D4E97286A7 for ; Tue, 14 May 2019 12:23:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C9AA8286A8; Tue, 14 May 2019 12:23:24 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 75300286A4 for ; Tue, 14 May 2019 12:23:24 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hQWRj-0000Cg-PO; Tue, 14 May 2019 12:22:15 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hQWRi-00009a-D3 for xen-devel@lists.xenproject.org; Tue, 14 May 2019 12:22:14 +0000 X-Inumbo-ID: e73a3f5b-7642-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.101.70]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id e73a3f5b-7642-11e9-8980-bc764e045a96; Tue, 14 May 2019 12:22:13 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F28BF15AD; Tue, 14 May 2019 05:22:12 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E2C263F71E; Tue, 14 May 2019 05:22:11 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Tue, 14 May 2019 13:21:29 +0100 Message-Id: <20190514122136.28215-21-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190514122136.28215-1-julien.grall@arm.com> References: <20190514122136.28215-1-julien.grall@arm.com> Subject: [Xen-devel] [PATCH MM-PART2 v2 12/19] xen/arm32: head: Always zero r3 before update a page-table entry X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Oleksandr_Tyshchenko@epam.com, Julien Grall , Stefano Stabellini , Andrii_Anisov@epam.com MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP The boot code is using r2 and r3 to hold the page-table entry value. While r2 is always updated before storing the value, this is not always the case for r3. Thankfully today, r3 will always be zero when we care. But this is difficult to track and error-prone. So always zero r3 within the few instructions before the write the page-table entry. Signed-off-by: Julien Grall --- Changes in v2: - Use 0x0 instead of 0 - Remove a duplicate mov r3, #0 --- xen/arch/arm/arm32/head.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S index 3448817aab..18ded49a04 100644 --- a/xen/arch/arm/arm32/head.S +++ b/xen/arch/arm/arm32/head.S @@ -270,6 +270,7 @@ cpu_init_done: orr r2, r2, #PT_UPPER(MEM) /* r2:r3 := section map */ orr r2, r2, #PT_LOWER(MEM) lsl r1, r1, #3 /* r1 := Slot offset */ + mov r3, #0x0 strd r2, r3, [r4, r1] /* Mapping of paddr(start) */ mov r6, #1 /* r6 := identity map now in place */ @@ -372,11 +373,11 @@ paging: /* Add UART to the fixmap table */ ldr r1, =xen_fixmap /* r1 := vaddr (xen_fixmap) */ - mov r3, #0 lsr r2, r11, #THIRD_SHIFT lsl r2, r2, #THIRD_SHIFT /* 4K aligned paddr of UART */ orr r2, r2, #PT_UPPER(DEV_L3) orr r2, r2, #PT_LOWER(DEV_L3) /* r2:r3 := 4K dev map including UART */ + mov r3, #0x0 strd r2, r3, [r1, #(FIXMAP_CONSOLE*8)] /* Map it in the first fixmap's slot */ 1: @@ -388,6 +389,7 @@ paging: orr r2, r2, #PT_LOWER(PT) /* r2:r3 := table map of xen_fixmap */ ldr r4, =FIXMAP_ADDR(0) mov r4, r4, lsr #(SECOND_SHIFT - 3) /* r4 := Slot for FIXMAP(0) */ + mov r3, #0x0 strd r2, r3, [r1, r4] /* Map it in the fixmap's slot */ /* Use a virtual address to access the UART. */