From patchwork Mon Jan 4 19:58:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandre Ghiti X-Patchwork-Id: 356523 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, 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 952E6C433DB for ; Mon, 4 Jan 2021 20:14:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 578A82226A for ; Mon, 4 Jan 2021 20:14:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728011AbhADUNu (ORCPT ); Mon, 4 Jan 2021 15:13:50 -0500 Received: from mslow2.mail.gandi.net ([217.70.178.242]:38518 "EHLO mslow2.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727672AbhADUNu (ORCPT ); Mon, 4 Jan 2021 15:13:50 -0500 Received: from relay2-d.mail.gandi.net (unknown [217.70.183.194]) by mslow2.mail.gandi.net (Postfix) with ESMTP id 43C443AF870; Mon, 4 Jan 2021 20:02:03 +0000 (UTC) X-Originating-IP: 90.112.190.212 Received: from debian.home (lfbn-gre-1-231-212.w90-112.abo.wanadoo.fr [90.112.190.212]) (Authenticated sender: alex@ghiti.fr) by relay2-d.mail.gandi.net (Postfix) with ESMTPSA id 977CF40003; Mon, 4 Jan 2021 20:00:59 +0000 (UTC) From: Alexandre Ghiti To: Paul Walmsley , Palmer Dabbelt , Zong Li , Anup Patel , Christoph Hellwig , Ard Biesheuvel , Arnd Bergmann , linux-efi@vger.kernel.org, linux-arch@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Alexandre Ghiti Subject: [RFC PATCH 02/12] riscv: Protect the kernel linear mapping Date: Mon, 4 Jan 2021 14:58:30 -0500 Message-Id: <20210104195840.1593-3-alex@ghiti.fr> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210104195840.1593-1-alex@ghiti.fr> References: <20210104195840.1593-1-alex@ghiti.fr> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org The kernel is now mapped at the end of the address space and it should be accessed through this mapping only: so map the whole kernel in the linear mapping as read only. Signed-off-by: Alexandre Ghiti --- arch/riscv/include/asm/page.h | 9 ++++++++- arch/riscv/mm/init.c | 29 +++++++++++++++++++++-------- 2 files changed, 29 insertions(+), 9 deletions(-) diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h index 98188e315e8d..a93e35aaa717 100644 --- a/arch/riscv/include/asm/page.h +++ b/arch/riscv/include/asm/page.h @@ -102,8 +102,15 @@ extern unsigned long pfn_base; extern unsigned long max_low_pfn; extern unsigned long min_low_pfn; extern unsigned long kernel_virt_addr; +extern uintptr_t load_pa, load_sz; + +#define linear_mapping_pa_to_va(x) ((void *)((unsigned long)(x) + va_pa_offset)) +#define kernel_mapping_pa_to_va(x) \ + ((void *)((unsigned long) (x) + va_kernel_pa_offset)) +#define __pa_to_va_nodebug(x) \ + ((x >= load_pa && x < load_pa + load_sz) ? \ + kernel_mapping_pa_to_va(x): linear_mapping_pa_to_va(x)) -#define __pa_to_va_nodebug(x) ((void *)((unsigned long) (x) + va_pa_offset)) #define linear_mapping_va_to_pa(x) ((unsigned long)(x) - va_pa_offset) #define kernel_mapping_va_to_pa(x) \ ((unsigned long)(x) - va_kernel_pa_offset) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 9d06ff0e015a..7b87c14f1d24 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -159,8 +159,6 @@ void __init setup_bootmem(void) { phys_addr_t mem_start = 0; phys_addr_t start, end = 0; - phys_addr_t vmlinux_end = __pa_symbol(&_end); - phys_addr_t vmlinux_start = __pa_symbol(&_start); u64 i; /* Find the memory region containing the kernel */ @@ -168,7 +166,7 @@ void __init setup_bootmem(void) phys_addr_t size = end - start; if (!mem_start) mem_start = start; - if (start <= vmlinux_start && vmlinux_end <= end) + if (start <= load_pa && (load_pa + load_sz) <= end) BUG_ON(size == 0); } @@ -179,8 +177,13 @@ void __init setup_bootmem(void) */ memblock_enforce_memory_limit(mem_start - PAGE_OFFSET); - /* Reserve from the start of the kernel to the end of the kernel */ - memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start); + /* + * Reserve from the start of the kernel to the end of the kernel + * and make sure we align the reservation on PMD_SIZE since we will + * map the kernel in the linear mapping as read-only: we do not want + * any allocation to happen between _end and the next pmd aligned page. + */ + memblock_reserve(load_pa, (load_sz + PMD_SIZE - 1) & ~(PMD_SIZE - 1)); max_pfn = PFN_DOWN(memblock_end_of_DRAM()); max_low_pfn = max_pfn; @@ -438,7 +441,9 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size) #error "setup_vm() is called from head.S before relocate so it should not use absolute addressing." #endif -static uintptr_t load_pa, load_sz; +uintptr_t load_pa, load_sz; +EXPORT_SYMBOL(load_pa); +EXPORT_SYMBOL(load_sz); static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size) { @@ -596,9 +601,17 @@ static void __init setup_vm_final(void) map_size = best_map_size(start, end - start); for (pa = start; pa < end; pa += map_size) { - va = (uintptr_t)__va(pa); + pgprot_t prot = PAGE_KERNEL; + + /* Protect the kernel mapping that lies in the linear mapping */ + if (pa >= __pa(_start) && pa < __pa(_end)) + prot = PAGE_KERNEL_READ; + + /* Make sure we get virtual addresses in the linear mapping */ + va = (uintptr_t)linear_mapping_pa_to_va(pa); + create_pgd_mapping(swapper_pg_dir, va, pa, - map_size, PAGE_KERNEL); + map_size, prot); } }