From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753952Ab2IQAuo (ORCPT ); Sun, 16 Sep 2012 20:50:44 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33425 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753102Ab2IQAtn (ORCPT ); Sun, 16 Sep 2012 20:49:43 -0400 Message-Id: <20120917003637.706801413@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 17 Sep 2012 01:37:48 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Will Deacon , Catalin Marinas , Russell King Subject: [ 083/135] ARM: 7487/1: mm: avoid setting nG bit for user mappings that arent present In-Reply-To: <20120917003625.784119135@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 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 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Will Deacon commit 47f1204329237a0f8655f5a9f14a38ac81946ca1 upstream. Swap entries are encoding in ptes such that !pte_present(pte) and pte_file(pte). The remaining bits of the descriptor are used to identify the swapfile and offset within it to the swap entry. When writing such a pte for a user virtual address, set_pte_at unconditionally sets the nG bit, which (in the case of LPAE) will corrupt the swapfile offset and lead to a BUG: [ 140.494067] swap_free: Unused swap offset entry 000763b4 [ 140.509989] BUG: Bad page map in process rs:main Q:Reg pte:0ec76800 pmd:8f92e003 This patch fixes the problem by only setting the nG bit for user mappings that are actually present. Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Ben Hutchings --- arch/arm/include/asm/pgtable.h | 34 ++++++++++++++++++---------------- arch/arm/mm/flush.c | 2 -- 2 files changed, 18 insertions(+), 18 deletions(-) --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -232,6 +232,18 @@ static inline pte_t *pmd_page_vaddr(pmd_ #define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext) #define pte_clear(mm,addr,ptep) set_pte_ext(ptep, __pte(0), 0) +#define pte_none(pte) (!pte_val(pte)) +#define pte_present(pte) (pte_val(pte) & L_PTE_PRESENT) +#define pte_write(pte) (!(pte_val(pte) & L_PTE_RDONLY)) +#define pte_dirty(pte) (pte_val(pte) & L_PTE_DIRTY) +#define pte_young(pte) (pte_val(pte) & L_PTE_YOUNG) +#define pte_exec(pte) (!(pte_val(pte) & L_PTE_XN)) +#define pte_special(pte) (0) + +#define pte_present_user(pte) \ + ((pte_val(pte) & (L_PTE_PRESENT | L_PTE_USER)) == \ + (L_PTE_PRESENT | L_PTE_USER)) + #if __LINUX_ARM_ARCH__ < 6 static inline void __sync_icache_dcache(pte_t pteval) { @@ -243,25 +255,15 @@ extern void __sync_icache_dcache(pte_t p static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pteval) { - if (addr >= TASK_SIZE) - set_pte_ext(ptep, pteval, 0); - else { + unsigned long ext = 0; + + if (addr < TASK_SIZE && pte_present_user(pteval)) { __sync_icache_dcache(pteval); - set_pte_ext(ptep, pteval, PTE_EXT_NG); + ext |= PTE_EXT_NG; } -} -#define pte_none(pte) (!pte_val(pte)) -#define pte_present(pte) (pte_val(pte) & L_PTE_PRESENT) -#define pte_write(pte) (!(pte_val(pte) & L_PTE_RDONLY)) -#define pte_dirty(pte) (pte_val(pte) & L_PTE_DIRTY) -#define pte_young(pte) (pte_val(pte) & L_PTE_YOUNG) -#define pte_exec(pte) (!(pte_val(pte) & L_PTE_XN)) -#define pte_special(pte) (0) - -#define pte_present_user(pte) \ - ((pte_val(pte) & (L_PTE_PRESENT | L_PTE_USER)) == \ - (L_PTE_PRESENT | L_PTE_USER)) + set_pte_ext(ptep, pteval, ext); +} #define PTE_BIT_FUNC(fn,op) \ static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; } --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -236,8 +236,6 @@ void __sync_icache_dcache(pte_t pteval) struct page *page; struct address_space *mapping; - if (!pte_present_user(pteval)) - return; if (cache_is_vipt_nonaliasing() && !pte_exec(pteval)) /* only flush non-aliasing VIPT caches for exec mappings */ return;