From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933159AbcHNLAV (ORCPT ); Sun, 14 Aug 2016 07:00:21 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51905 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933133AbcHNLAP (ORCPT ); Sun, 14 Aug 2016 07:00:15 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Catalin Marinas" , "Will Deacon" , "Mark Rutland" , "Shaokun Zhang" Date: Sat, 13 Aug 2016 18:42:51 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 205/305] arm64: mm: remove page_mapping check in __sync_icache_dcache In-Reply-To: X-SA-Exim-Connect-IP: 92.40.249.202 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.37-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Shaokun Zhang commit 20c27a4270c775d7ed661491af8ac03264d60fc6 upstream. __sync_icache_dcache unconditionally skips the cache maintenance for anonymous pages, under the assumption that flushing is only required in the presence of D-side aliases [see 7249b79f6b4cc ("arm64: Do not flush the D-cache for anonymous pages")]. Unfortunately, this breaks migration of anonymous pages holding self-modifying code, where userspace cannot be reasonably expected to reissue maintenance instructions in response to a migration. This patch fixes the problem by removing the broken page_mapping(page) check from the cache syncing code, otherwise we may end up fetching and executing stale instructions from the PoU. Cc: Catalin Marinas Cc: Will Deacon Cc: Mark Rutland Reviewed-by: Catalin Marinas Signed-off-by: Shaokun Zhang Signed-off-by: Will Deacon [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- arch/arm64/mm/flush.c | 4 ---- 1 file changed, 4 deletions(-) --- a/arch/arm64/mm/flush.c +++ b/arch/arm64/mm/flush.c @@ -74,10 +74,6 @@ void __sync_icache_dcache(pte_t pte, uns { struct page *page = pte_page(pte); - /* no flushing needed for anonymous pages */ - if (!page_mapping(page)) - return; - if (!test_and_set_bit(PG_dcache_clean, &page->flags)) { __flush_dcache_area(page_address(page), PAGE_SIZE << compound_order(page));