From patchwork Mon Jun 13 14:45:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 12879910 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7EAF7C433EF for ; Mon, 13 Jun 2022 18:31:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245459AbiFMSbN (ORCPT ); Mon, 13 Jun 2022 14:31:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245640AbiFMSa4 (ORCPT ); Mon, 13 Jun 2022 14:30:56 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41ECEB57B8 for ; Mon, 13 Jun 2022 07:46:39 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C45FD61416 for ; Mon, 13 Jun 2022 14:46:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31F9EC3411C; Mon, 13 Jun 2022 14:46:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1655131598; bh=7beXEY+KBTc27ISfxObaHwnTrPVTfmi/8un0rUMxTzE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VNKIdDwzEXUG4oPyasOVCIkbt9JWod52V0UojtL8zjEpcLhti4P+0GG/YdiRgtHUQ gTH2I4qdpocZCUSpVmyULFhEyW9nQXk7CX+MuE1k+xxxs4CYgY3XsglTLawapIbTdA zhaBFKxAiTNAYITWZT68naKcUcED1FPNAeKVd8Kqnjg8Usx4Np6Itj0djr8Jx715f4 ACXOMy6xT2lOIIk5EQ0EdRGF0zKUZb3L8khCHOPpzHBZhnVnlCTk/Bc09uOpahqyQo E+K0MRCaEG8bJnf9cyvPPXwc+qtMbTtxIQR/IhCTyzu2EkVj0oKR+QCZaFheMK5sOa cRMyLQYsSnDiA== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: linux-hardening@vger.kernel.org, Ard Biesheuvel , Marc Zyngier , Will Deacon , Mark Rutland , Kees Cook , Catalin Marinas , Mark Brown , Anshuman Khandual Subject: [PATCH v4 14/26] arm64: head: create a temporary FDT mapping in the initial ID map Date: Mon, 13 Jun 2022 16:45:38 +0200 Message-Id: <20220613144550.3760857-15-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220613144550.3760857-1-ardb@kernel.org> References: <20220613144550.3760857-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3280; h=from:subject; bh=7beXEY+KBTc27ISfxObaHwnTrPVTfmi/8un0rUMxTzE=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBip02IYL10J7/TdsI+a0ICE7ToYeWDjwX1yKy0PNf9 kGHVvN+JAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYqdNiAAKCRDDTyI5ktmPJDjeC/ 9S1MPIhA9zngXHFMlY8JVKU3QRCAEL0ocCBbqeSdhUvZBXrtMXgq2sdxgDpb2aZTnjKiyz3zWJKnSZ a1wjK6kI50HYTwCVL47VaLrL54BsIrg1DMcvyG6ZZh3xqtyjNktNito10c/0m4xu/Wg/k8b4SKJqcv nwHFVW0YFUVYnTt/vLV4ySTyYDbDM5GOqrbz9z53PDOdmh9MEMvfcRMSCw41SnG0ZERUj+u0aaZyyF DSY3Msu3I4YdMqG/LwyDvMEV/jyfmdW+Fo80P/EWkFtu5xEZHSdFhz9z+zQiICyEsV4HAN/IvhjA4H XW5ZeKu8BsNXLzFoPBC/tZmEoMKxjz9xgIC0ZwoiZj1nsTw427NOBpbWuE5+z4n92cBOxdIbaQ+HIR MrqXsBoPQYlYnc3sYsbXsb4z385smd1uWl4D4iP/tqUrS9YqWFHrX1z3uJDOxpWnzZ6Ynm7a74NV/u sDpyQ7XSUT3TSMS29PDWGCcPEoqmeNhHd7irwHNZLEg9A= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org We need to access the DT very early to get at the command line and the KASLR seed, which currently means we rely on some hacks to call into the kernel before really calling into the kernel, which is undesirable. So instead, let's create a mapping for the FDT in the initial ID map, which is feasible now that it has been extended to cover more than a single page or block, and can be updated in place to remap other output addresses. Signed-off-by: Ard Biesheuvel --- arch/arm64/include/asm/kernel-pgtable.h | 6 ++++-- arch/arm64/kernel/head.S | 14 +++++++++++++- 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h index 5395e5a04f35..02e59fa8f293 100644 --- a/arch/arm64/include/asm/kernel-pgtable.h +++ b/arch/arm64/include/asm/kernel-pgtable.h @@ -8,6 +8,7 @@ #ifndef __ASM_KERNEL_PGTABLE_H #define __ASM_KERNEL_PGTABLE_H +#include #include #include @@ -88,10 +89,11 @@ /* the initial ID map may need two extra pages if it needs to be extended */ #if VA_BITS < 48 -#define INIT_IDMAP_DIR_SIZE (INIT_DIR_SIZE + (2 * PAGE_SIZE)) +#define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE) #else -#define INIT_IDMAP_DIR_SIZE INIT_DIR_SIZE +#define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE) #endif +#define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE) /* Initial memory map size */ #if ARM64_KERNEL_USES_PMD_MAPS diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index f1497f7b4da0..8283ff848328 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -83,6 +83,7 @@ * * Register Scope Purpose * x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0 + * x22 create_idmap() .. start_kernel() ID map VA of the DT blob * x23 primary_entry() .. start_kernel() physical misalignment/KASLR offset * x28 clear_page_tables() callee preserved temp register * x19/x20 __primary_switch() callee preserved temp registers @@ -348,7 +349,7 @@ SYM_FUNC_START_LOCAL(create_idmap) #endif adrp x0, init_idmap_pg_dir adrp x3, _text - adrp x6, _end + adrp x6, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE mov x7, SWAPPER_RX_MMUFLAGS map_memory x0, x1, x3, x6, x7, x3, IDMAP_PGD_ORDER, x10, x11, x12, x13, x14, EXTRA_SHIFT @@ -362,6 +363,17 @@ SYM_FUNC_START_LOCAL(create_idmap) mov x6, #SWAPPER_BLOCK_SHIFT bl remap_region + /* Remap the FDT after the kernel image */ + adrp x1, _text + adrp x22, _end + SWAPPER_BLOCK_SIZE + bic x2, x22, #SWAPPER_BLOCK_SIZE - 1 + bfi x22, x21, #0, #SWAPPER_BLOCK_SHIFT // remapped FDT address + add x3, x2, #MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE + bic x4, x21, #SWAPPER_BLOCK_SIZE - 1 + mov x5, SWAPPER_RW_MMUFLAGS + mov x6, #SWAPPER_BLOCK_SHIFT + bl remap_region + /* * Since the page tables have been populated with non-cacheable * accesses (MMU disabled), invalidate those tables again to