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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 300B7C3A59F for ; Tue, 27 Aug 2019 00:13:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0296620850 for ; Tue, 27 Aug 2019 00:13:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=sifive.com header.i=@sifive.com header.b="H9Kk7EsS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727555AbfH0AN0 (ORCPT ); Mon, 26 Aug 2019 20:13:26 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:41181 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726307AbfH0ANZ (ORCPT ); Mon, 26 Aug 2019 20:13:25 -0400 Received: by mail-pg1-f195.google.com with SMTP id x15so11574403pgg.8 for ; Mon, 26 Aug 2019 17:13:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=Iw6JNWRP3igEjjbsY2DrjeSufzb3AiZwDl6GtE2wNmQ=; b=H9Kk7EsSWtOGwDBBXZTaiLDAh5a1CmQ5esXABzmC/dKl4QkDAHnLeMUeqiCnWxa1gP 6B3Etsb8xeqdUYbeTB7DjXOuVflwu03YeST4etZacSsHDo0XzcX5F5cZ8v4LMjVAsMyh yWsZ1SqONunlv2fYuisr0dDHh2luMguN3vfvwun6XlvEWS6XKjzAR8YIY/eqdbEdKAzX o8bBrWJbnScDvU/btyFAiwrxjQZs91OpmUD4fP5cKTGM1SPVth8BuZUhCrAHQKcZOnSC Cm/TTNqRq1j9Iyk0UY+5dl2/QIG4arHrAKczc5/DteCLRIeccmm+6pywJNCEYYZOoSfT zwJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=Iw6JNWRP3igEjjbsY2DrjeSufzb3AiZwDl6GtE2wNmQ=; b=sIBBZKLnuDEvdBPuXDGOJrbp0uYTWOz/b8A004/VRzlydT709XZlejL3Y0dWE5SgqA X197nnAxS8tt2VSh45bHUwndOaqQXM+UdtLJyUivYPd9F94HweZMTp9VZTXawfaqwKq3 9cIUEuMnZVZN9wEyrrag6CknbrT7W59uBByToN1DYa/U327dBZtaivUqEF1HMU85jH85 LyLiJMMAT/a/5BPcB/eFRpETqQGVYKCM3EzAQ77FaHr87ZRMtjh4SXW+xOuHJLVZw1gH GT36xp31fCf963+jwp1qJs4D82Ed/rQOKvx53yLhKz1n2ne4ZNqaxnbFSrGVgFDDOF+D mk/Q== X-Gm-Message-State: APjAAAUtBs/1yEcEfNk6V5sbNuJVx7dT/63okHkvKi+go+rUdmJWzjO/ koWIUZlOOrlXRVz/M6pfpYJw1g== X-Google-Smtp-Source: APXvYqx6u1wwF4tgUg81853PTvaK/j5q0KHWzOBzXOEEHdr0Jg/DZ7R06Oea/jeHX1iyLYWkTf4fMw== X-Received: by 2002:a65:5a8c:: with SMTP id c12mr18420410pgt.73.1566864804459; Mon, 26 Aug 2019 17:13:24 -0700 (PDT) Received: from localhost ([12.206.222.5]) by smtp.gmail.com with ESMTPSA id j11sm566443pjb.11.2019.08.26.17.13.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Aug 2019 17:13:23 -0700 (PDT) Date: Mon, 26 Aug 2019 17:13:23 -0700 (PDT) From: Paul Walmsley X-X-Sender: paulw@viisi.sifive.com To: Anup Patel cc: Palmer Dabbelt , Atish Patra , Alistair Francis , Christoph Hellwig , Anup Patel , "linux-riscv@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v2] RISC-V: Fix FIXMAP area corruption on RV32 systems In-Reply-To: <20190819051345.81097-1-anup.patel@wdc.com> Message-ID: References: <20190819051345.81097-1-anup.patel@wdc.com> User-Agent: Alpine 2.21.9999 (DEB 301 2018-08-15) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Anup, On Mon, 19 Aug 2019, Anup Patel wrote: > Currently, various virtual memory areas of Linux RISC-V are organized > in increasing order of their virtual addresses is as follows: > 1. User space area (This is lowest area and starts at 0x0) > 2. FIXMAP area > 3. VMALLOC area > 4. Kernel area (This is highest area and starts at PAGE_OFFSET) > > The maximum size of user space aread is represented by TASK_SIZE. > > On RV32 systems, TASK_SIZE is defined as VMALLOC_START which causes the > user space area to overlap the FIXMAP area. This allows user space apps > to potentially corrupt the FIXMAP area and kernel OF APIs will crash > whenever they access corrupted FDT in the FIXMAP area. > > On RV64 systems, TASK_SIZE is set to fixed 256GB and no other areas > happen to overlap so we don't see any FIXMAP area corruptions. > > This patch fixes FIXMAP area corruption on RV32 systems by setting > TASK_SIZE to FIXADDR_START. This part -- the TASK_SIZE change -- makes sense to me. However, the patch also changes FIXADDR_SIZE to be defined in terms of page table-related constants. Previously, FIXADDR_SIZE was based on __end_of_fixed_addresses, as it is for most other architectures. The part of the patch that changes FIXADDR_SIZE seems unrelated to the actual fix. If that's indeed the case -- that the change to FIXADDR_SIZE is unrelated from the fix -- could you please split that into a separate patch, with a description of the rationale? I think I understand why you're proposing it, but it seems odd to explicitly connect it to page table-related constants, rather than the contents of "enum fixed_addresses", and I'm reluctant to merge that part of this patch without a bit more discussion. > We also move FIXADDR_TOP, FIXADDR_SIZE, and FIXADDR_START defines to > asm/pgtable.h so that we can avoid cyclic header includes. > > Signed-off-by: Anup Patel > Tested-by: Alistair Francis > Reviewed-by: Christoph Hellwig > --- > Changes since v1: > - Drop braces from "#define FIXADDR_TOP" > --- > arch/riscv/include/asm/fixmap.h | 4 ---- > arch/riscv/include/asm/pgtable.h | 12 ++++++++++-- > 2 files changed, 10 insertions(+), 6 deletions(-) > > diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h > index 9c66033c3a54..161f28d04a07 100644 > --- a/arch/riscv/include/asm/fixmap.h > +++ b/arch/riscv/include/asm/fixmap.h > @@ -30,10 +30,6 @@ enum fixed_addresses { > __end_of_fixed_addresses > }; > > -#define FIXADDR_SIZE (__end_of_fixed_addresses * PAGE_SIZE) > -#define FIXADDR_TOP (VMALLOC_START) > -#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) > - > #define FIXMAP_PAGE_IO PAGE_KERNEL > > #define __early_set_fixmap __set_fixmap > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > index a364aba23d55..c24a083b3e12 100644 > --- a/arch/riscv/include/asm/pgtable.h > +++ b/arch/riscv/include/asm/pgtable.h > @@ -420,14 +420,22 @@ static inline void pgtable_cache_init(void) > #define VMALLOC_END (PAGE_OFFSET - 1) > #define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE) > > +#define FIXADDR_TOP VMALLOC_START > +#ifdef CONFIG_64BIT > +#define FIXADDR_SIZE PMD_SIZE > +#else > +#define FIXADDR_SIZE PGDIR_SIZE > +#endif > +#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) > + > /* > - * Task size is 0x4000000000 for RV64 or 0xb800000 for RV32. > + * Task size is 0x4000000000 for RV64 or 0x9fc00000 for RV32. > * Note that PGDIR_SIZE must evenly divide TASK_SIZE. > */ > #ifdef CONFIG_64BIT > #define TASK_SIZE (PGDIR_SIZE * PTRS_PER_PGD / 2) > #else > -#define TASK_SIZE VMALLOC_START > +#define TASK_SIZE FIXADDR_START > #endif > > #include > -- > 2.17.1 > - Paul