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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,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_GIT 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 54C00C072B1 for ; Fri, 17 May 2019 16:48:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2750E2168B for ; Fri, 17 May 2019 16:48:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="l5axbd7G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727763AbfEQQsG (ORCPT ); Fri, 17 May 2019 12:48:06 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:34991 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727570AbfEQQry (ORCPT ); Fri, 17 May 2019 12:47:54 -0400 Received: by mail-pl1-f194.google.com with SMTP id g5so3608274plt.2 for ; Fri, 17 May 2019 09:47:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=CqKPKWAOqqK2fAPeJ19AHkkbMpccuE5V5twNlxY2yj4=; b=l5axbd7GCjC8UzCQX6le433fYI5Gy+AP17dysVHzpJd5K1V3v/AHW4gWkJNCz7RvkX U/Da5n4quZkQBum7RcbcB/GoUQGFlxfPOuZ2L8sPSnntSKwbhQY1PEaQHXxJ91PjHzMn phj4VIypQewbe385bAXnxglk7G8q2eho9KcGk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=CqKPKWAOqqK2fAPeJ19AHkkbMpccuE5V5twNlxY2yj4=; b=KvUxMxbwPf5ziKhtxKi6GYU8aLBuDwWA8obQg7ohvDuuocXkuKlby4fAlBxio0b2B3 bXPNZxg3PnhOeuXn6kPNW4L1czkVoRB72w39vbV2lPfhRy2PeB7ENNO4IbhIH0lIbisT qeHh0Zusnv6vmelzBSllrnLoyBViXq4r+In0mJJBCqVV3R7CaYevDNhfwfruKb0Gqn2B +zLBdaXkU/18i15A1kajY5GpxW4b3dnfPSwgeQuS4pcGH4D9VQWV9PZ4Iit41ZrwkaF7 8AHT4smSyA8Kw9XwqpKxagWT3oFxfBsw3iAgSeTtGlGbAo7TGzorU/IcRmjyoirJ1V3V 08JQ== X-Gm-Message-State: APjAAAV7bmr3WikBN4no6FXpKEylszrRhwbSGmU5Cljequ4qcG0PDN8o u7IyD5v6lUjc/SL5COwuCfRl1qO9aXm7Rg== X-Google-Smtp-Source: APXvYqyAp8uRsjVVx2sdnL7aIY5IBJRUMYDjonUYiJUCfdadaA7UoNqRxgke+HnZZ6Yy3quetwwBow== X-Received: by 2002:a17:902:ac98:: with SMTP id h24mr1729914plr.265.1558111673755; Fri, 17 May 2019 09:47:53 -0700 (PDT) Received: from smtp.gmail.com ([2620:15c:202:1:fa53:7765:582b:82b9]) by smtp.gmail.com with ESMTPSA id l141sm12229810pfd.24.2019.05.17.09.47.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 17 May 2019 09:47:53 -0700 (PDT) From: Stephen Boyd To: linux-kernel@vger.kernel.org Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, Evan Green , Rob Herring , Bjorn Andersson , Andy Gross , Will Deacon , Catalin Marinas , Dan Williams Subject: [RFC/PATCH 3/5] memremap: Add support for read-only memory mappings Date: Fri, 17 May 2019 09:47:44 -0700 Message-Id: <20190517164746.110786-4-swboyd@chromium.org> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog In-Reply-To: <20190517164746.110786-1-swboyd@chromium.org> References: <20190517164746.110786-1-swboyd@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sometimes we have memories that are supposed to be read-only, but when we map these regions the best we can do is map them as write-back with MEMREMAP_WB. Introduce a read-only memory mapping (MEMREMAP_RO) that allows us to map reserved memory regions as read-only. This way, we're less likely to see these special memory regions become corrupted by stray writes to them. Cc: Evan Green Cc: Rob Herring Cc: Bjorn Andersson Cc: Andy Gross Cc: Will Deacon Cc: Catalin Marinas Cc: Dan Williams Signed-off-by: Stephen Boyd --- include/linux/io.h | 1 + kernel/iomem.c | 15 +++++++++++++-- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/io.h b/include/linux/io.h index 32e30e8fb9db..16c7f4498869 100644 --- a/include/linux/io.h +++ b/include/linux/io.h @@ -159,6 +159,7 @@ enum { MEMREMAP_WC = 1 << 2, MEMREMAP_ENC = 1 << 3, MEMREMAP_DEC = 1 << 4, + MEMREMAP_RO = 1 << 5, }; void *memremap(resource_size_t offset, size_t size, unsigned long flags); diff --git a/kernel/iomem.c b/kernel/iomem.c index f7525e14ebc6..8d3cf74a32cb 100644 --- a/kernel/iomem.c +++ b/kernel/iomem.c @@ -19,6 +19,13 @@ static void *arch_memremap_wb(resource_size_t offset, unsigned long size) } #endif +#ifndef arch_memremap_ro +static void *arch_memremap_ro(resource_size_t offset, unsigned long size) +{ + return NULL; +} +#endif + #ifndef arch_memremap_can_ram_remap static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size, unsigned long flags) @@ -84,7 +91,10 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags) } /* Try all mapping types requested until one returns non-NULL */ - if (flags & MEMREMAP_WB) { + if ((flags & MEMREMAP_RO) && is_ram != REGION_INTERSECTS) + addr = arch_memremap_ro(offset, size); + + if (!addr && (flags & MEMREMAP_WB)) { /* * MEMREMAP_WB is special in that it can be satisifed * from the direct map. Some archs depend on the @@ -103,7 +113,8 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags) * address mapping. Enforce that this mapping is not aliasing * System RAM. */ - if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) { + if (!addr && is_ram == REGION_INTERSECTS && + (flags != MEMREMAP_WB || flags != MEMREMAP_RO)) { WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n", &offset, (unsigned long) size); return NULL; -- Sent by a computer through tubes