From patchwork Fri Jun 24 15:06:37 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 12894746 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 0A050C43334 for ; Fri, 24 Jun 2022 15:09:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=FOurAzs4a8A6IC5S2tn6aZFIuLRWzR+9z6mRfQ+aE20=; b=bvrm1MZBrJHKvg ULbu1rPgM3v9uXkJYx4PObBc9XYrqUtZ6JApB16npRyFxzy4YO6NIPAeDcL75YvMCaZi1rUS6Vebi EAAiJLzopFlCDnmKr3XlXWPIhxKTK2WUOEh3/ULl6Q6JYwRZSIrz/Rg5BXIEqIMwZnGKZseHMLtFI kXZd4PvwP8zf08TUn7ySChw9fmiQ+2q0zsFJOfLEPsCEZIb9V2C5+OUMkIQ1XpL0pXtjGnVy4nv04 6YG7sy/iQT68WOIyuDtOkXkcOHjUFSL+vAxNAg44/NO/ksgRfbpHtYBQeJeFJeIgfi6ySCiv3aKqV 5nnsUlXpJvKLaXYFdS7A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o4kv5-002ioi-D2; Fri, 24 Jun 2022 15:08:27 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o4ku9-002iOP-Au for linux-arm-kernel@lists.infradead.org; Fri, 24 Jun 2022 15:07:31 +0000 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 ams.source.kernel.org (Postfix) with ESMTPS id EDD6EB828E0; Fri, 24 Jun 2022 15:07:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C229FC341C6; Fri, 24 Jun 2022 15:07:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1656083245; bh=s3JvUhBYEJDd0ZqtHxd2crGhZ2ZETuhTxYys0m9YjQo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sk0eKnSamJnfCS1h2u3YxTYiDlp6t/8/xjYxYZ+5r0CmvqF4o1APJ/OcZgPQ2JYgi wMrbv6+3QiW5iLoiI48GTljcjfR1FStYhJjVwxAlB/2DYttmHFK5Ah6ogY8G3T5Y/w I7Jd23wD9aaQQPCWQxn093FfIEjBOIhW7amQNueOJ5Yv+5RCJzx5e6BZ+woPovFJLz A9WZCCvkZiHPTkcMlVPchCh0zz/fA8peF4OXue5ZInPJiTyffbE16ANaHvcItHU2hA AEo1q8w4oo2/I2ErUdUAqlGcoVAXHJ9nNf+OiUH5FqhKwGTTCfY0iRxv/1SZ48w3VM 1IOD8QJFwnKBA== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Marc Zyngier , Will Deacon , Mark Rutland , Kees Cook , Catalin Marinas , Mark Brown , Anshuman Khandual Subject: [PATCH v5 07/21] arm64: head: split off idmap creation code Date: Fri, 24 Jun 2022 17:06:37 +0200 Message-Id: <20220624150651.1358849-8-ardb@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220624150651.1358849-1-ardb@kernel.org> References: <20220624150651.1358849-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5970; h=from:subject; bh=s3JvUhBYEJDd0ZqtHxd2crGhZ2ZETuhTxYys0m9YjQo=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBitdLy+vcEnXVF4tjgr2Aqg9Q+44VVRNJUoCrjhMk3 /2PQQviJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYrXS8gAKCRDDTyI5ktmPJLWdC/ 9NLsZYFlqBlTk6NyjyLKKFvwWQU19YXLlpk4bSZAx6q1nkw8CIqf4JjMMuyu0bI8D03ftNOPkesER/ b1mIea0ppErwpfDTSmZhrDWVDE+bayTMSQkAEUb3hB5zHp8xeWepo7SCDf4BKecSFj1CA7T+VYU9Bm 5SJBZUQ4L+PiQniflH12Wh/u4wb3RFfqrUN1R2yERNiCw4k2bwdtt4u/l4hMvi/i4Hqf/FFIdhUKrj oPW/jpalj9SJq5ltqH4Xy5q+0hcYP2M8WTUDuhLDx70nH0oOt29AoVjS32MBOqwa/IW0d7wcE5iALY pSlpcOfHRUYH0F2BOsFSAGh4fsxCwFnuaqo6M2t/c+xPX3GiYe71dQPT+VS+WyZk7LuOHPPYKcfsi3 UcDe457lasN588oRpbrvpeVKJqTN1qHRLv0nL1L+gXiMmvX5W7aoMdG4n4NnMvVzzHcfsxuH2O0sgp MqO2i5S8ttve8zAvV10ER5DbclNaME2l4oUzIH0L1rGlk= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220624_080729_707279_A2CB2538 X-CRM114-Status: GOOD ( 17.67 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Split off the creation of the ID map page tables, so that we can avoid running it again unnecessarily when KASLR is in effect (which only randomizes the virtual placement). This will permit us to drop some explicit cache maintenance to the PoC which was necessary because the cache invalidation being performed on some global variables might otherwise clobber unrelated variables that happen to share a cacheline. Signed-off-by: Ard Biesheuvel --- arch/arm64/kernel/head.S | 101 ++++++++++---------- 1 file changed, 52 insertions(+), 49 deletions(-) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index eb54c0289c8a..1cbc52097bf9 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -84,7 +84,7 @@ * Register Scope Purpose * x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0 * x23 primary_entry() .. start_kernel() physical misalignment/KASLR offset - * x28 __create_page_tables() callee preserved temp register + * x28 clear_page_tables() callee preserved temp register * x19/x20 __primary_switch() callee preserved temp registers * x24 __primary_switch() .. relocate_kernel() current RELR displacement */ @@ -94,7 +94,10 @@ SYM_CODE_START(primary_entry) adrp x23, __PHYS_OFFSET and x23, x23, MIN_KIMG_ALIGN - 1 // KASLR offset, defaults to 0 bl set_cpu_boot_mode_flag - bl __create_page_tables + bl clear_page_tables + bl create_idmap + bl create_kernel_mapping + /* * The following calls CPU setup code, see arch/arm64/mm/proc.S for * details. @@ -122,6 +125,35 @@ SYM_CODE_START_LOCAL(preserve_boot_args) b dcache_inval_poc // tail call SYM_CODE_END(preserve_boot_args) +SYM_FUNC_START_LOCAL(clear_page_tables) + mov x28, lr + + /* + * Invalidate the init page tables to avoid potential dirty cache lines + * being evicted. Other page tables are allocated in rodata as part of + * the kernel image, and thus are clean to the PoC per the boot + * protocol. + */ + adrp x0, init_pg_dir + adrp x1, init_pg_end + bl dcache_inval_poc + + /* + * Clear the init page tables. + */ + adrp x0, init_pg_dir + adrp x1, init_pg_end + sub x1, x1, x0 +1: stp xzr, xzr, [x0], #16 + stp xzr, xzr, [x0], #16 + stp xzr, xzr, [x0], #16 + stp xzr, xzr, [x0], #16 + subs x1, x1, #64 + b.ne 1b + + ret x28 +SYM_FUNC_END(clear_page_tables) + /* * Macro to populate page table entries, these entries can be pointers to the next level * or last level entries pointing to physical memory. @@ -231,44 +263,8 @@ SYM_CODE_END(preserve_boot_args) populate_entries \tbl, \rtbl, \istart, \iend, \flags, #SWAPPER_BLOCK_SIZE, \tmp .endm -/* - * Setup the initial page tables. We only setup the barest amount which is - * required to get the kernel running. The following sections are required: - * - identity mapping to enable the MMU (low address, TTBR0) - * - first few MB of the kernel linear mapping to jump to once the MMU has - * been enabled - */ -SYM_FUNC_START_LOCAL(__create_page_tables) - mov x28, lr - /* - * Invalidate the init page tables to avoid potential dirty cache lines - * being evicted. Other page tables are allocated in rodata as part of - * the kernel image, and thus are clean to the PoC per the boot - * protocol. - */ - adrp x0, init_pg_dir - adrp x1, init_pg_end - bl dcache_inval_poc - - /* - * Clear the init page tables. - */ - adrp x0, init_pg_dir - adrp x1, init_pg_end - sub x1, x1, x0 -1: stp xzr, xzr, [x0], #16 - stp xzr, xzr, [x0], #16 - stp xzr, xzr, [x0], #16 - stp xzr, xzr, [x0], #16 - subs x1, x1, #64 - b.ne 1b - - mov x7, SWAPPER_MM_MMUFLAGS - - /* - * Create the identity mapping. - */ +SYM_FUNC_START_LOCAL(create_idmap) adrp x0, idmap_pg_dir adrp x3, __idmap_text_start // __pa(__idmap_text_start) @@ -319,12 +315,23 @@ SYM_FUNC_START_LOCAL(__create_page_tables) */ #endif adr_l x6, __idmap_text_end // __pa(__idmap_text_end) + mov x7, SWAPPER_MM_MMUFLAGS map_memory x0, x1, x3, x6, x7, x3, IDMAP_PGD_ORDER, x10, x11, x12, x13, x14, EXTRA_SHIFT /* - * Map the kernel image (starting with PHYS_OFFSET). + * Since the page tables have been populated with non-cacheable + * accesses (MMU disabled), invalidate those tables again to + * remove any speculatively loaded cache lines. */ + dmb sy + + adrp x0, idmap_pg_dir + adrp x1, idmap_pg_end + b dcache_inval_poc // tail call +SYM_FUNC_END(create_idmap) + +SYM_FUNC_START_LOCAL(create_kernel_mapping) adrp x0, init_pg_dir mov_q x5, KIMAGE_VADDR // compile time __va(_text) add x5, x5, x23 // add KASLR displacement @@ -332,6 +339,7 @@ SYM_FUNC_START_LOCAL(__create_page_tables) adrp x3, _text // runtime __pa(_text) sub x6, x6, x3 // _end - _text add x6, x6, x5 // runtime __va(_end) + mov x7, SWAPPER_MM_MMUFLAGS map_memory x0, x1, x5, x6, x7, x3, (VA_BITS - PGDIR_SHIFT), x10, x11, x12, x13, x14 @@ -342,16 +350,10 @@ SYM_FUNC_START_LOCAL(__create_page_tables) */ dmb sy - adrp x0, idmap_pg_dir - adrp x1, idmap_pg_end - bl dcache_inval_poc - adrp x0, init_pg_dir adrp x1, init_pg_end - bl dcache_inval_poc - - ret x28 -SYM_FUNC_END(__create_page_tables) + b dcache_inval_poc // tail call +SYM_FUNC_END(create_kernel_mapping) /* * Initialize CPU registers with task-specific and cpu-specific context. @@ -836,7 +838,8 @@ SYM_FUNC_START_LOCAL(__primary_switch) pre_disable_mmu_workaround msr sctlr_el1, x20 // disable the MMU isb - bl __create_page_tables // recreate kernel mapping + bl clear_page_tables + bl create_kernel_mapping // Recreate kernel mapping tlbi vmalle1 // Remove any stale TLB entries dsb nsh