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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D297C77B75 for ; Tue, 18 Apr 2023 09:31:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231308AbjDRJbs (ORCPT ); Tue, 18 Apr 2023 05:31:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231290AbjDRJbl (ORCPT ); Tue, 18 Apr 2023 05:31:41 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AA2F37686 for ; Tue, 18 Apr 2023 02:31:38 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B1439168F; Tue, 18 Apr 2023 02:32:21 -0700 (PDT) Received: from [10.1.27.157] (C02CF1NRLVDN.cambridge.arm.com [10.1.27.157]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 289DE3F5A1; Tue, 18 Apr 2023 02:31:35 -0700 (PDT) Message-ID: <775d92fc-9195-88bf-4a1c-51b74185c07d@arm.com> Date: Tue, 18 Apr 2023 10:31:33 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 Subject: Re: [PATCH v3 34/60] arm64: head: Move early kernel mapping routines into C code Content-Language: en-US To: Ard Biesheuvel , linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Marc Zyngier , Mark Rutland , Anshuman Khandual , Kees Cook References: <20230307140522.2311461-1-ardb@kernel.org> <20230307140522.2311461-35-ardb@kernel.org> From: Ryan Roberts In-Reply-To: <20230307140522.2311461-35-ardb@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/03/2023 14:04, Ard Biesheuvel wrote: > The asm version of the kernel mapping code works fine for creating a > coarse grained identity map, but for mapping the kernel down to its > exact boundaries with the right attributes, it is not suitable. This is > why we create a preliminary RWX kernel mapping first, and then rebuild > it from scratch later on. > > So let's reimplement this in C, in a way that will make it unnecessary > to create the kernel page tables yet another time in paging_init(). > > Signed-off-by: Ard Biesheuvel > --- > [...] > diff --git a/arch/arm64/kernel/pi/map_kernel.c b/arch/arm64/kernel/pi/map_kernel.c > new file mode 100644 > index 0000000000000000..b573c964c7d88d1b > --- /dev/null > +++ b/arch/arm64/kernel/pi/map_kernel.c > @@ -0,0 +1,171 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +// Copyright 2023 Google LLC > +// Author: Ard Biesheuvel > + > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > +#include > +#include > +#include > + > +#include "pi.h" > + > +extern const u8 __eh_frame_start[], __eh_frame_end[]; > + > +extern void idmap_cpu_replace_ttbr1(void *pgdir); > + > +static void map_segment(pgd_t *pg_dir, u64 *pgd, u64 va_offset, > + void *start, void *end, pgprot_t prot, > + bool may_use_cont, int root_level) > +{ > + map_range(pgd, ((u64)start + va_offset) & ~PAGE_OFFSET, > + ((u64)end + va_offset) & ~PAGE_OFFSET, (u64)start, > + prot, root_level, (pte_t *)pg_dir, may_use_cont, 0); I don't understand what you are doing with ~PAGE_OFFSET here. Is this intended to be page alignment with PAGE_MASK? I'm guessing not, because you would want to forward align the end address in that case. > +} > + > +static void unmap_segment(pgd_t *pg_dir, u64 va_offset, void *start, > + void *end, int root_level) > +{ > + map_segment(pg_dir, NULL, va_offset, start, end, __pgprot(0), > + false, root_level); > +} > + > [...] > diff --git a/arch/arm64/kernel/pi/map_range.c b/arch/arm64/kernel/pi/map_range.c > new file mode 100644 > index 0000000000000000..61cbd6e82418c033 > --- /dev/null > +++ b/arch/arm64/kernel/pi/map_range.c > @@ -0,0 +1,87 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +// Copyright 2023 Google LLC > +// Author: Ard Biesheuvel > + > +#include > +#include > + > +#include > +#include > +#include > + > +#include "pi.h" > + > +/** > + * map_range - Map a contiguous range of physical pages into virtual memory > + * > + * @pte: Address of physical pointer to array of pages to > + * allocate page tables from > + * @start: Virtual address of the start of the range > + * @end: Virtual address of the end of the range (exclusive) > + * @pa: Physical address of the start of the range > + * @level: Translation level for the mapping > + * @tbl: The level @level page table to create the mappings in > + * @may_use_cont: Whether the use of the contiguous attribute is allowed > + * @va_offset: Offset between a physical page and its current mapping > + * in the VA space > + */ > +void __init map_range(u64 *pte, u64 start, u64 end, u64 pa, pgprot_t prot, > + int level, pte_t *tbl, bool may_use_cont, u64 va_offset) va_offset is always 0 (because the memory at *pte is id-mapped). Can it be dropped? Or perhaps you are using this function later, once the memory is no longer id-mapped? > +{ > + u64 cmask = (level == 3) ? CONT_PTE_SIZE - 1 : U64_MAX; > + u64 protval = pgprot_val(prot) & ~PTE_TYPE_MASK; > + int lshift = (3 - level) * (PAGE_SHIFT - 3); > + u64 lmask = (PAGE_SIZE << lshift) - 1; > + > + start &= PAGE_MASK; > + pa &= PAGE_MASK; > +