From patchwork Fri Oct 30 20:19:03 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 7529151 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id B187EBEEA4 for ; Fri, 30 Oct 2015 20:26:59 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D6CC0206FF for ; Fri, 30 Oct 2015 20:26:58 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 00B32206F7 for ; Fri, 30 Oct 2015 20:26:58 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZsGEY-0007GU-BC; Fri, 30 Oct 2015 20:25:10 +0000 Received: from mga02.intel.com ([134.134.136.20]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZsGEU-00060S-B6 for linux-arm-kernel@lists.infradead.org; Fri, 30 Oct 2015 20:25:06 +0000 Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga101.jf.intel.com with ESMTP; 30 Oct 2015 13:24:45 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,220,1444719600"; d="scan'208";a="839590321" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.39]) by fmsmga002.fm.intel.com with ESMTP; 30 Oct 2015 13:24:45 -0700 Subject: [for 4.3-final PATCH v2] memremap: fix highmem support From: Dan Williams To: linux-arm-kernel@lists.infradead.org Date: Fri, 30 Oct 2015 16:19:03 -0400 Message-ID: <20151030201758.13415.13264.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-9-g687f MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151030_132506_461149_32722D25 X-CRM114-Status: GOOD ( 15.60 ) X-Spam-Score: -7.9 (-------) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: rmk+kernel@arm.linux.org.uk, "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Ard Biesheuvel Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-5.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently memremap checks if the range is "System RAM" and returns the kernel linear address. This is broken for highmem platforms where a range may be "System RAM", but is not part of the kernel linear mapping. Fallback to ioremap_cache() in these cases, to let the arch code attempt to handle it. Note that ARM ioremap will WARN when attempting to remap ram, and in that case the caller needs to be fixed. For this reason, existing ioremap_cache() usages for ARM are already trained to avoid attempts to remap ram. The impact of this bug is low for now since the pmem driver is the only user of memremap(), but this is important to fix before more conversions to memremap arrive in 4.4. Cc: Rafael J. Wysocki Reported-by: Ard Biesheuvel Signed-off-by: Dan Williams Acked-by: Ard Biesheuvel --- kernel/memremap.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/kernel/memremap.c b/kernel/memremap.c index 72b0c66628b6..9d6b55587eaa 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -24,6 +24,16 @@ __weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size) } #endif +static void *try_ram_remap(resource_size_t offset, size_t size) +{ + struct page *page = pfn_to_page(offset >> PAGE_SHIFT); + + /* In the simple case just return the existing linear address */ + if (!PageHighMem(page)) + return __va(offset); + return NULL; /* fallback to ioremap_cache */ +} + /** * memremap() - remap an iomem_resource as cacheable memory * @offset: iomem resource start address @@ -66,8 +76,8 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags) * the requested range is potentially in "System RAM" */ if (is_ram == REGION_INTERSECTS) - addr = __va(offset); - else + addr = try_ram_remap(offset, size); + if (!addr) addr = ioremap_cache(offset, size); }