From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751533AbcA1X4y (ORCPT ); Thu, 28 Jan 2016 18:56:54 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:32883 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750997AbcA1X4v (ORCPT ); Thu, 28 Jan 2016 18:56:51 -0500 From: Nicolai Stange To: Richard Weinberger Cc: Dan Williams Cc: Alexander Viro Cc: Jeff Dike Cc: Nicolai Stange Cc: Andrew Morton Cc: Dan Williams Cc: user-mode-linux-devel@lists.sourceforge.net Cc: user-mode-linux-user@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org Subject: [PATCH] um: asm/page.h: zero out a pte's high value in set_pte_val() Date: Fri, 29 Jan 2016 00:56:48 +0100 Message-ID: <871t91i7gf.fsf@gmail.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 16da306849d0 ("um: kill pfn_t") introduced a compile warning for defconfig: arch/um/kernel/skas/mmu.c:38:206: warning: right shift count >= width of type [-Wshift-count-overflow] Aforementioned patch changes the definition of the phys_to_pfn() macro from ((pfn_t) ((p) >> PAGE_SHIFT)) to ((p) >> PAGE_SHIFT) This effectively changes the phys_to_pfn() expansion's type from unsigned long long to unsigned long. Through the callchain init_stub_pte()->mk_pte(), the expansion of phys_to_pfn() is (indirectly) fed into the 'phys' argument of the pte_set_val(pte, phys, prot) macro, eventually leading to (pte).pte_high = (phys) >> 32; This results in the warning from above. Since UML only deals with 32 bit addresses, the upper 32 bits from 'phys' used to be zero anyway. Zero out the pte value's high part in pte_set_val() in order to get rid of the offending shift. Fixes: 16da306849d0 ("um: kill pfn_t") Signed-off-by: Nicolai Stange --- arch/um/include/asm/page.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h index e13d41c..61e235f 100644 --- a/arch/um/include/asm/page.h +++ b/arch/um/include/asm/page.h @@ -46,8 +46,8 @@ typedef struct { unsigned long pgd; } pgd_t; smp_wmb(); \ (to).pte_low = (from).pte_low; }) #define pte_is_zero(pte) (!((pte).pte_low & ~_PAGE_NEWPAGE) && !(pte).pte_high) -#define pte_set_val(pte, phys, prot) \ - ({ (pte).pte_high = (phys) >> 32; \ +#define pte_set_val(pte, phys, prot) \ + ({ (pte).pte_high = 0; \ (pte).pte_low = (phys) | pgprot_val(prot); }) #define pmd_val(x) ((x).pmd) -- 2.7.0