From patchwork Wed Feb 26 16:57:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 11406791 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D333592A for ; Wed, 26 Feb 2020 16:58:07 +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 A9F002467F for ; Wed, 26 Feb 2020 16:58:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="flLUzGgW"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ct2vSQGY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A9F002467F 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+patchwork-linux-arm=patchwork.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=flLUzGgWjAj/6QZI5u3pk59ueD Zpe4D9oCF3LZ+LldCUxETd0+wChkoOdKRKPSRJLXoTCBma5MGget2tgAEoOSTbuxaDxZRiVQqrnuZ cK37csa/DUO2usF/HlgBQYtoTVTeyMLnUzTKNKPVwtUunKmauI71z8TdFxqmoiDL+DeImh4VeeSI2 W5xSmVhUj8X+awBIX0ohkJ9nvC3BBdSp0b44YVBmi+wnCT26+Q0Li6jaudqfKurYkgAsGBqubYAqC EBcIGvAwwFeSqSmyiOVtojzcDsTcVk7ANKVQLYSpv6hU468YZku1nWl/0nlfFUgaUmRtQagOZktPr Cnbu2fkg==; 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 1j700c-00031C-Kg; Wed, 26 Feb 2020 16:58:06 +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 1j700L-0002oa-Gp for linux-arm-kernel@lists.infradead.org; Wed, 26 Feb 2020 16:57:50 +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 7235624683; Wed, 26 Feb 2020 16:57:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582736269; bh=u6UNh9AxsmaZvMVFcXaOuu9HBc8jrZmXLZzpHbnjRV4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ct2vSQGYPQgQCLm+j0XQuXIjZVpEl44NBKJXr6bbccQiPi6WgvAYWP7Ssd2mNJQF+ rzcVPjAtnPrbWvEAfORZZHLU5BzZNiFv4VbKQP5AFtlICaw3f2pDhgKpD3V3g7IcZW U7j565si4nwg30EgxhPkI4wABCwFElcC2K1i2Bto= From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 1/5] efi/arm: Work around missing cache maintenance in decompressor handover Date: Wed, 26 Feb 2020 17:57:34 +0100 Message-Id: <20200226165738.11201-2-ardb@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200226165738.11201-1-ardb@kernel.org> References: <20200226165738.11201-1-ardb@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200226_085749_605030_9D67DD22 X-CRM114-Status: GOOD ( 13.88 ) X-Spam-Score: -5.2 (-----) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-5.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender 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: linux-efi@vger.kernel.org, Nicolas Pitre , Tony Lindgren , Marc Zyngier , Linus Walleij , Russell King , Catalin Marinas , Ard Biesheuvel MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.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