From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29ADCC35671 for ; Mon, 24 Feb 2020 12:17:55 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C61832080D for ; Mon, 24 Feb 2020 12:17:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="qnGbDp69"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hYgbTdxw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C61832080D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=toMHs9SxjEDho4lFjhNiPQXjtpzQQ1FlEgogTQjKMMc=; b=qnGbDp697F7ZINkBYwsV4gTFFH 6uj9sZFRkLiyPR170zyB26EG04z9Tao6e4nnzS4+Hf6fSMu0eh0F2q339rNKsm3ojuvdXivt3AeMD 3SpqZ5bWZa/QP7x807HoBCdq9efKaWWCCBzcHn0FUNKdWlKxsj2sf+4ZLW66upOfy0e0R2N0S16Nh hB93s7qOqxbk6G3OlPXYN+0hSGBC4b3iQktTnOZEqlah+Dd5w/jlKuf72G+rB4rlwy+fxbfVArAAP /Z1cGGY5/66GuEGWZRpzQ9EwrqG3onRuJ7gfpH4cwsUDPeUYzpvrCe/L9jg5umZZ6bOSB4fcHGjMV JRF5fc9Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j6CgL-0007kc-8e; Mon, 24 Feb 2020 12:17:53 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j6CgA-0007ZM-40 for linux-arm-kernel@lists.infradead.org; Mon, 24 Feb 2020 12:17:43 +0000 Received: from e123331-lin.home (amontpellier-657-1-18-247.w109-210.abo.wanadoo.fr [109.210.65.247]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1ED9A20838; Mon, 24 Feb 2020 12:17:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582546661; bh=u6UNh9AxsmaZvMVFcXaOuu9HBc8jrZmXLZzpHbnjRV4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hYgbTdxwi6yCT/hMQnnjI1Fq0ei2PoBYS7CeQUddSaMyjzWEqyo4WTh6KiYOf0mV9 0pQtmENszU7+wxVSV462uuVcWCgP/UZn64Ea5h6VB2rxKImgLWt3l4XGBQ6iZbOnR+ WUdmSu8po/EMHpr1tCTkDgMncCKhiMsy20ppbQEk= From: Ard Biesheuvel To: linux-efi@vger.kernel.org Subject: [PATCH v3 1/5] efi/arm: Work around missing cache maintenance in decompressor handover Date: Mon, 24 Feb 2020 13:17:29 +0100 Message-Id: <20200224121733.2202-2-ardb@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200224121733.2202-1-ardb@kernel.org> References: <20200224121733.2202-1-ardb@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200224_041742_197453_EA8014BC X-CRM114-Status: GOOD ( 14.52 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nicolas Pitre , Tony Lindgren , Marc Zyngier , Linus Walleij , Russell King , Catalin Marinas , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org The EFI stub executes within the context of the zImage as it was loaded by the firmware, which means it is treated as an ordinary PE/COFF executable, which is loaded into memory, and cleaned to the PoU to ensure that it can be executed safely while the MMU and caches are on. When the EFI stub hands over to the decompressor, we clean the caches by set/way and disable the MMU and D-cache, to comply with the Linux boot protocol for ARM. However, cache maintenance by set/way is not sufficient to ensure that subsequent instruction fetches and data accesses done with the MMU off see the correct data. This means that proceeding as we do currently is not safe, especially since we also perform data accesses with the MMU off, from a literal pool as well as the stack. So let's kick this can down the road a bit, and jump into the relocated zImage before disabling the caches. This removes the requirement to perform any by-VA cache maintenance on the original PE/COFF executable, but it does require that the relocated zImage is cleaned to the PoC, which is currently not the case. This will be addressed in a subsequent patch. Signed-off-by: Ard Biesheuvel --- arch/arm/boot/compressed/head.S | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index 088b0a060876..39f7071d47c7 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -1461,6 +1461,17 @@ ENTRY(efi_stub_entry) @ Preserve return value of efi_entry() in r4 mov r4, r0 bl cache_clean_flush + + @ The PE/COFF loader might not have cleaned the code we are + @ running beyond the PoU, and so calling cache_off below from + @ inside the PE/COFF loader allocated region is unsafe. Let's + @ assume our own zImage relocation code did a better job, and + @ jump into its version of this routine before proceeding. + ldr r0, [sp] @ relocated zImage + ldr r1, .Ljmp + sub r1, r0, r1 + mov pc, r1 @ no mode switch +0: bl cache_off @ Set parameters for booting zImage according to boot protocol @@ -1469,18 +1480,15 @@ ENTRY(efi_stub_entry) mov r0, #0 mov r1, #0xFFFFFFFF mov r2, r4 - - @ Branch to (possibly) relocated zImage that is in [sp] - ldr lr, [sp] - ldr ip, =start_offset - add lr, lr, ip - mov pc, lr @ no mode switch + b __efi_start efi_load_fail: @ Return EFI_LOAD_ERROR to EFI firmware on error. ldr r0, =0x80000001 ldmfd sp!, {ip, pc} ENDPROC(efi_stub_entry) + .align 2 +.Ljmp: .long start - 0b #endif .align -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel