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=-8.8 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 47023C31E4B for ; Fri, 14 Jun 2019 20:37:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A7312084D for ; Fri, 14 Jun 2019 20:37:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="DPpqEvR2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728312AbfFNUhh (ORCPT ); Fri, 14 Jun 2019 16:37:37 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:46431 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727297AbfFNUhW (ORCPT ); Fri, 14 Jun 2019 16:37:22 -0400 Received: by mail-pg1-f195.google.com with SMTP id v9so2140160pgr.13 for ; Fri, 14 Jun 2019 13:37:22 -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=TIy8YQDmiH0lGYDV1tdQuIF92/7kUVyaQcmdzLpFsEA=; b=DPpqEvR2xRVIvswlW2ndF1y9QKk/EJuzPD08Z5oPj4JN719FIPwvtEToWha++Fa1Hp Qb8VmkV96OQsM+BbP3DUKWo9ridoF9L2RV+ZNbYHAh3544fZJLPFVqEXyCPQQGyc1ld8 9f5H6/eK3vxM8AsDZbD/TWhdCBBhZQTLmxhYw= 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=TIy8YQDmiH0lGYDV1tdQuIF92/7kUVyaQcmdzLpFsEA=; b=ccUm9QC9vfBsqWSPnNnTnROV/26dSd72X39flGYGxmgVk3w77gXjjh775uEDjjPSV2 zvbZ3517WyaiVVFJBWGaoRoiaVog3CiC6u52kjNKJLmYa5zo7EpGIX2fujEL0p0nxA8E /CcAkRB+9LVFhlJNT60mqQsbt7xl1o2UWJK/B65zbEnp++Y08joUe1vOlWwojpH73r96 HqzaMyDRxECQ+T+YRhNfLET6XtcmukaeQQ5uVaASDn7cecphKUKGUSopRAtZ3l1mr4o8 Ql24h+InIZi4lixItgKVqfqI5T0V32G0wwLO5qRMKsdRdIgDflgbHUihcBInbxqArI+r i8MQ== X-Gm-Message-State: APjAAAV9zPvl+OSfpZ4CNneq8ItRbFCeAyxZpGtgWLzUZDEPZAroJOk1 4PLGAdevSNaKn+yBYMHM+jvNXQ== X-Google-Smtp-Source: APXvYqxmpfHSDjrUYD6uZNYIRRn0cr0CR+UNJC8dHrCxflAPdm/P9a9hwNIpx+rOpjwL7hA2RLbd6A== X-Received: by 2002:a63:81c6:: with SMTP id t189mr36883280pgd.293.1560544641989; Fri, 14 Jun 2019 13:37:21 -0700 (PDT) Received: from smtp.gmail.com ([2620:15c:202:1:fa53:7765:582b:82b9]) by smtp.gmail.com with ESMTPSA id x5sm3673187pjp.21.2019.06.14.13.37.21 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 14 Jun 2019 13:37:21 -0700 (PDT) From: Stephen Boyd To: Dan Williams Cc: linux-kernel@vger.kernel.org, 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 Subject: [PATCH v2 3/5] memremap: Add support for read-only memory mappings Date: Fri, 14 Jun 2019 13:37:15 -0700 Message-Id: <20190614203717.75479-4-swboyd@chromium.org> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog In-Reply-To: <20190614203717.75479-1-swboyd@chromium.org> References: <20190614203717.75479-1-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 Reviewed-by: Bjorn Andersson 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 93c264444510..10d5ef0ff09e 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 satisfied * 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