From patchwork Thu Jul 30 16:53:45 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 6904971 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 3EB6B9F39D for ; Thu, 30 Jul 2015 17:03:06 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 3F55A20412 for ; Thu, 30 Jul 2015 17:03:05 +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 36D5120495 for ; Thu, 30 Jul 2015 17:03:04 +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 1ZKrDM-0001K4-AQ; Thu, 30 Jul 2015 17:01:52 +0000 Received: from mga11.intel.com ([192.55.52.93]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZKrBJ-00078X-VF for linux-arm-kernel@lists.infradead.org; Thu, 30 Jul 2015 16:59:46 +0000 Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga102.fm.intel.com with ESMTP; 30 Jul 2015 09:59:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,577,1432623600"; d="scan'208";a="738956724" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.11]) by orsmga001.jf.intel.com with ESMTP; 30 Jul 2015 09:59:27 -0700 Subject: [PATCH v3 01/24] mm: enhance region_is_ram() to region_intersects() From: Dan Williams To: tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com Date: Thu, 30 Jul 2015 12:53:45 -0400 Message-ID: <20150730165345.33962.80299.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <20150730165155.33962.64121.stgit@dwillia2-desk3.amr.corp.intel.com> References: <20150730165155.33962.64121.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-8-g92dd MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150730_095946_062689_2A68B606 X-CRM114-Status: GOOD ( 18.94 ) X-Spam-Score: -8.3 (--------) 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: linux-arch@vger.kernel.org, toshi.kani@hp.com, linux-nvdimm@lists.01.org, mcgrof@suse.com, linux-kernel@vger.kernel.org, rmk+kernel@arm.linux.org.uk, hch@lst.de, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-5.6 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 region_is_ram() is used to prevent the establishment of aliased mappings to physical "System RAM" with incompatible cache settings. However, it uses "-1" to indicate both "unknown" memory ranges (ranges not described by platform firmware) and "mixed" ranges (where the parameters describe a range that partially overlaps "System RAM"). Fix this up by explicitly tracking the "unknown" vs "mixed" resource cases and returning REGION_INTERSECTS, REGION_MIXED, or REGION_DISJOINT. This re-write also adds support for detecting when the requested region completely eclipses all of a resource. Note, the implementation treats overlaps between "unknown" and the requested memory type as REGION_INTERSECTS. Finally, other memory types can be passed in by name, for now the only usage "System RAM". Suggested-by: Luis R. Rodriguez Reviewed-by: Toshi Kani Signed-off-by: Dan Williams --- include/linux/mm.h | 9 +++++++- kernel/resource.c | 61 +++++++++++++++++++++++++++++++--------------------- 2 files changed, 44 insertions(+), 26 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 2e872f92dbac..84b05ebedb2d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) } extern int page_is_ram(unsigned long pfn); -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); + +enum { + REGION_INTERSECTS, + REGION_DISJOINT, + REGION_MIXED, +}; + +int region_intersects(resource_size_t offset, size_t size, const char *type); /* Support for virtually mapped pages */ struct page *vmalloc_to_page(const void *addr); diff --git a/kernel/resource.c b/kernel/resource.c index fed052a1bc9f..f150dbbe6f62 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -492,40 +492,51 @@ int __weak page_is_ram(unsigned long pfn) } EXPORT_SYMBOL_GPL(page_is_ram); -/* - * Search for a resouce entry that fully contains the specified region. - * If found, return 1 if it is RAM, 0 if not. - * If not found, or region is not fully contained, return -1 +/** + * region_intersects() - determine intersection of region with known resources + * @start: region start address + * @size: size of region + * @name: name of resource (in iomem_resource) * - * Used by the ioremap functions to ensure the user is not remapping RAM and is - * a vast speed up over walking through the resource table page by page. + * Check if the specified region partially overlaps or fully eclipses a + * resource identified by @name. Return REGION_DISJOINT if the region + * does not overlap @name, return REGION_MIXED if the region overlaps + * @type and another resource, and return REGION_INTERSECTS if the + * region overlaps @type and no other defined resource. Note, that + * REGION_INTERSECTS is also returned in the case when the specified + * region overlaps RAM and undefined memory holes. + * + * region_intersect() is used by memory remapping functions to ensure + * the user is not remapping RAM and is a vast speed up over walking + * through the resource table page by page. */ -int region_is_ram(resource_size_t start, unsigned long size) +int region_intersects(resource_size_t start, size_t size, const char *name) { - struct resource *p; - resource_size_t end = start + size - 1; unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY; - const char *name = "System RAM"; - int ret = -1; + resource_size_t end = start + size - 1; + int type = 0; int other = 0; + struct resource *p; read_lock(&resource_lock); for (p = iomem_resource.child; p ; p = p->sibling) { - if (p->end < start) - continue; - - if (p->start <= start && end <= p->end) { - /* resource fully contains region */ - if ((p->flags != flags) || strcmp(p->name, name)) - ret = 0; - else - ret = 1; - break; - } - if (end < p->start) - break; /* not found */ + bool is_type = strcmp(p->name, name) == 0 && p->flags == flags; + + if (start >= p->start && start <= p->end) + is_type ? type++ : other++; + if (end >= p->start && end <= p->end) + is_type ? type++ : other++; + if (p->start >= start && p->end <= end) + is_type ? type++ : other++; } read_unlock(&resource_lock); - return ret; + + if (other == 0) + return type ? REGION_INTERSECTS : REGION_DISJOINT; + + if (type) + return REGION_MIXED; + + return REGION_DISJOINT; } void __weak arch_remove_reservations(struct resource *avail)