From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756318Ab0JOPUK (ORCPT ); Fri, 15 Oct 2010 11:20:10 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:53997 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756153Ab0JOPUI (ORCPT ); Fri, 15 Oct 2010 11:20:08 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:mime-version :content-type:content-transfer-encoding; b=H67UC6inEDewS91j1fO14e3kBYh8V0NGqD6d7Al9UbV4saW0c32gTVKrpWWfqVMLLf ao3jZnvud247k2MXm7bcnExQq6lhgIuqVmx55Wwbk3//icYDy7tEu5QO4f1iAr4uy/tI D/6A38f3e/Jo18GVUDOstq0c5g4Ys8mTQ9XCg= From: Felipe Contreras To: linux-main , linux-arm Cc: Linus Torvalds , Catalin Marinas , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Russell King , Andrew Morton , Richard Woodruff , Felipe Contreras Subject: [PATCH .36-rc8] arm: mm: allow, but warn, when issuing ioremap() on RAM Date: Fri, 15 Oct 2010 17:15:20 +0300 Message-Id: <1287152120-7201-1-git-send-email-felipe.contreras@gmail.com> X-Mailer: git-send-email 1.7.3.1.2.g7fe2b MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Catalin Marinas Drivers have been relying on this behavior, but done so wrongly. However, rather than breaking drivers from .35 to .36, we should warn on .36 and only break on .37. This way we give a chance for contributors to fix the issues. According to ARM, the behavior of having multiple mappings is unspecified from ARMv6+. This causes real issues specially on modern hardware, and specially with speculative prefetching. So drivers need to be fixed. Also, since current hardware has palliative meassures to deal with multiple mappings with the same memory type but diferent cacheability attributes, ensure that such restriction is taking place. Cc: Uwe Kleine-König Cc: Russell King Cc: Andrew Morton Cc: Richard Woodruff Signed-off-by: Catalin Marinas Signed-off-by: Felipe Contreras --- arch/arm/mm/ioremap.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c index ab50627..7dfd6dd 100644 --- a/arch/arm/mm/ioremap.c +++ b/arch/arm/mm/ioremap.c @@ -202,10 +202,14 @@ void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn, return NULL; /* - * Don't allow RAM to be mapped - this causes problems with ARMv6+ + * This causes problems with ARMv6+. Will be disallowed soon. + * Also avoid a second mapping with different shareability, which is + * not supposed to work anyway. */ if (WARN_ON(pfn_valid(pfn))) - return NULL; + if (__LINUX_ARM_ARCH__ >= 6 && + (mtype != MT_DEVICE_CACHED && mtype != MT_DEVICE_WC)) + mtype = MT_DEVICE_WC; type = get_mem_type(mtype); if (!type) -- 1.7.3.1.2.g7fe2b