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,URIBL_BLOCKED,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 EC26EC433E2 for ; Thu, 9 Jul 2020 21:14:08 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 B52E320672 for ; Thu, 9 Jul 2020 21:14:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="3jYkg4hB"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="vX8lbvip" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B52E320672 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+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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version: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:In-Reply-To:References:List-Owner; bh=rsfvCHZWg4wy5liTx9v+9Lel1Oyz58XAqGmAW6Lqhe4=; b=3jYkg4hBTVId2Msq09/asXmWTY Kf+oUubuO0u6PicWiiuLQ/uftwBcxZbcdIaAwPF3uZlREccxf03yX8rfHV7u1Mb1G1N3rZ5YFBiMX vXZMiYbFovAbRJDvzyHUlPg/1hufcmPMPrLUvlXa53GaZ03s52wOgUiT4ALfdsIzYZOLFHCyT8Bmm qHcUjr27NJ7uyprZtL/85zueWeYeApvcOFaekyKeZebWwrym21kyf3bHwiHcA20B9+bexMoV/2Fck d6WwOSEaYqnBhmrD4BHrsdrzyJ7G+VvHoo3b/6jzT0R+QPvYZz+U8urlAz/pGxpNHhN+jNuXHtcJP /QxkmxPQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jtdqZ-0002Mc-JO; Thu, 09 Jul 2020 21:12:47 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jtdqX-0002Lt-2j for linux-arm-kernel@lists.infradead.org; Thu, 09 Jul 2020 21:12:45 +0000 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (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 3F49520672; Thu, 9 Jul 2020 21:12:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594329163; bh=gdNAjKFjd7Ma8Rp8a9m6lG9yDDI4JcIuK5Ysm9BcJfo=; h=From:To:Cc:Subject:Date:From; b=vX8lbvipPcFGZK5JKbxkTM+SSTKJMhYFHfmf21jyuzdH1BrmFK7OJcFr7zdVGcMuD w/SCcToOZYAxLY2Ll+z7X+4Yyz6FdaocUw44kHF03+uFnbST7rryRx2OmI7i17/vls C+zfBHjImBxwPK5Z7eKQt7AJWzMzYmfCEnb6F8iw= From: Will Deacon To: linux-efi@vger.kernel.org Subject: [RFC PATCH] efi/libstub/arm64: Retain 2MB kernel Image alignment if !KASLR Date: Thu, 9 Jul 2020 22:12:37 +0100 Message-Id: <20200709211237.29455-1-will@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200709_171245_261980_9E2CACC4 X-CRM114-Status: GOOD ( 19.96 ) 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: Mark Rutland , Marc Zyngier , kernel-team@android.com, Catalin Marinas , David Brazdil , Will Deacon , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Since commit 82046702e288 ("efi/libstub/arm64: Replace 'preferred' offset with alignment check"), loading a relocatable arm64 kernel at a physical address which is not 2MB aligned and subsequently booting with EFI will leave the Image in-place, relying on the kernel to relocate itself early during boot. In conjunction with commit dd4bc6076587 ("arm64: warn on incorrect placement of the kernel by the bootloader"), which enables CONFIG_RELOCATABLE by default, this effectively means that entering an arm64 kernel loaded at an alignment smaller than 2MB with EFI (e.g. using QEMU) will result in silent relocation at runtime. Unfortunately, this has a subtle but confusing affect for developers trying to inspect the PC value during a crash and comparing it to the symbol addresses in vmlinux using tools such as 'nm' or 'addr2line'; all text addresses will be displaced by a sub-2MB offset, resulting in the wrong symbol being identified in many cases. Passing "nokaslr" on the command line or disabling "CONFIG_RANDOMIZE_BASE" does not help, since the EFI stub only copies the kernel Image to a 2MB boundary if it is not relocatable. Adjust the EFI stub for arm64 so that the minimum Image alignment is 2MB unless KASLR is in use. Cc: Ard Biesheuvel Cc: Mark Rutland Cc: Catalin Marinas Cc: Marc Zyngier Cc: David Brazdil Signed-off-by: Will Deacon --- Not massively happy with this patch, but also not massively happy that addr2line is so misleading without it. Thoughts? drivers/firmware/efi/libstub/arm64-stub.c | 25 +++++++++++-------- .../firmware/efi/libstub/efi-stub-helper.c | 2 +- 2 files changed, 15 insertions(+), 12 deletions(-) diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 7f6a57dec513..e5bfac79e5ac 100644 --- a/drivers/firmware/efi/libstub/arm64-stub.c +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -35,13 +35,16 @@ efi_status_t check_platform_features(void) } /* - * Relocatable kernels can fix up the misalignment with respect to - * MIN_KIMG_ALIGN, so they only require a minimum alignment of EFI_KIMG_ALIGN - * (which accounts for the alignment of statically allocated objects such as - * the swapper stack.) + * Although relocatable kernels can fix up the misalignment with respect to + * MIN_KIMG_ALIGN, the resulting virtual text addresses are subtly out of + * sync with those recorded in the vmlinux when kaslr is disabled but the + * image required relocation anyway. Therefore retain 2M alignment unless + * KASLR is in use. */ -static const u64 min_kimg_align = IS_ENABLED(CONFIG_RELOCATABLE) ? EFI_KIMG_ALIGN - : MIN_KIMG_ALIGN; +static u64 min_kimg_align(void) +{ + return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN; +} efi_status_t handle_kernel_image(unsigned long *image_addr, unsigned long *image_size, @@ -74,21 +77,21 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, kernel_size = _edata - _text; kernel_memsize = kernel_size + (_end - _edata); - *reserve_size = kernel_memsize + TEXT_OFFSET % min_kimg_align; + *reserve_size = kernel_memsize + TEXT_OFFSET % min_kimg_align(); if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { /* * If KASLR is enabled, and we have some randomness available, * locate the kernel at a randomized offset in physical memory. */ - status = efi_random_alloc(*reserve_size, min_kimg_align, + status = efi_random_alloc(*reserve_size, min_kimg_align(), reserve_addr, phys_seed); } else { status = EFI_OUT_OF_RESOURCES; } if (status != EFI_SUCCESS) { - if (IS_ALIGNED((u64)_text - TEXT_OFFSET, min_kimg_align)) { + if (IS_ALIGNED((u64)_text - TEXT_OFFSET, min_kimg_align())) { /* * Just execute from wherever we were loaded by the * UEFI PE/COFF loader if the alignment is suitable. @@ -99,7 +102,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, } status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, - ULONG_MAX, min_kimg_align); + ULONG_MAX, min_kimg_align()); if (status != EFI_SUCCESS) { efi_err("Failed to relocate kernel\n"); @@ -108,7 +111,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, } } - *image_addr = *reserve_addr + TEXT_OFFSET % min_kimg_align; + *image_addr = *reserve_addr + TEXT_OFFSET % min_kimg_align(); memcpy((void *)*image_addr, _text, kernel_size); return EFI_SUCCESS; diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index d40fd68c6bb2..6bca70bbb43d 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -19,7 +19,7 @@ #include "efistub.h" bool efi_nochunk; -bool efi_nokaslr; +bool efi_nokaslr = !IS_ENABLED(CONFIG_RANDOMIZE_BASE); bool efi_noinitrd; int efi_loglevel = CONSOLE_LOGLEVEL_DEFAULT; bool efi_novamap; -- 2.27.0.383.g050319c2ae-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel