From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752317Ab0HXSoV (ORCPT ); Tue, 24 Aug 2010 14:44:21 -0400 Received: from mga11.intel.com ([192.55.52.93]:32385 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751207Ab0HXSoT (ORCPT ); Tue, 24 Aug 2010 14:44:19 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.56,264,1280732400"; d="scan'208";a="831280769" From: "Luck, Tony" To: "Linus Torvalds" Cc: linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linux-ia64@vger.kernel.org Subject: [PATCH v2] guard page for stacks that grow upwards Date: Tue, 24 Aug 2010 11:44:18 -0700 Message-Id: <4c7413025613b269c@agluck-desktop.sc.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org pa-risc and ia64 have stacks that grow upwards. Check that they do not run into other mappings. By making VM_GROWSUP 0x0 on architectures that do not ever use it, we can avoid some unpleasant #ifdefs in check_stack_guard_page(). Signed-off-by: Tony Luck --- Built, booted & tested on ia64 Built for x86_64 (but not booted or tested) pa-risc - untested diff --git a/include/linux/mm.h b/include/linux/mm.h index 709f672..77e6336 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -78,7 +78,11 @@ extern unsigned int kobjsize(const void *objp); #define VM_MAYSHARE 0x00000080 #define VM_GROWSDOWN 0x00000100 /* general info on the segment */ +#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) #define VM_GROWSUP 0x00000200 +#else +#define VM_GROWSUP 0x00000000 +#endif #define VM_PFNMAP 0x00000400 /* Page-ranges managed without "struct page", just pure PFN */ #define VM_DENYWRITE 0x00000800 /* ETXTBSY on write attempts.. */ @@ -1330,8 +1334,10 @@ unsigned long ra_submit(struct file_ra_state *ra, /* Do stack extension */ extern int expand_stack(struct vm_area_struct *vma, unsigned long address); -#ifdef CONFIG_IA64 +#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) extern int expand_upwards(struct vm_area_struct *vma, unsigned long address); +#else +#define expand_upwards(vma, address) #endif extern int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address); diff --git a/mm/memory.c b/mm/memory.c index 2ed2267..6b2ab10 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2760,11 +2760,9 @@ out_release: } /* - * This is like a special single-page "expand_downwards()", - * except we must first make sure that 'address-PAGE_SIZE' + * This is like a special single-page "expand_{down|up}wards()", + * except we must first make sure that 'address{-|+}PAGE_SIZE' * doesn't hit another vma. - * - * The "find_vma()" will do the right thing even if we wrap */ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) { @@ -2783,6 +2781,15 @@ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned lo expand_stack(vma, address - PAGE_SIZE); } + if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { + struct vm_area_struct *next = vma->vm_next; + + /* As VM_GROWSDOWN but s/below/above/ */ + if (next && next->vm_start == address + PAGE_SIZE) + return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; + + expand_upwards(vma, address + PAGE_SIZE); + } return 0; } diff --git a/mm/mmap.c b/mm/mmap.c index 331e51a..6128dc8 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1716,9 +1716,6 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns * PA-RISC uses this for its stack; IA64 for its Register Backing Store. * vma is the last one with address > vma->vm_end. Have to extend vma. */ -#ifndef CONFIG_IA64 -static -#endif int expand_upwards(struct vm_area_struct *vma, unsigned long address) { int error;