diff options
Diffstat (limited to 'arch/x86/mm/mmap_64.c')
| -rw-r--r-- | arch/x86/mm/mmap_64.c | 119 |
1 files changed, 102 insertions, 17 deletions
diff --git a/arch/x86/mm/mmap_64.c b/arch/x86/mm/mmap_64.c index ffb71a31bb6e..8cf03ea651f8 100644 --- a/arch/x86/mm/mmap_64.c +++ b/arch/x86/mm/mmap_64.c @@ -1,32 +1,117 @@ -/* Copyright 2005 Andi Kleen, SuSE Labs. - * Licensed under GPL, v.2 +/* + * linux/arch/x86-64/mm/mmap.c + * + * flexible mmap layout support + * + * Based on code by Ingo Molnar and Andi Kleen, copyrighted + * as follows: + * + * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina. + * All Rights Reserved. + * Copyright 2005 Andi Kleen, SUSE Labs. + * Copyright 2007 Jiri Kosina, SUSE Labs. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * */ + +#include <linux/personality.h> #include <linux/mm.h> -#include <linux/sched.h> #include <linux/random.h> +#include <linux/limits.h> +#include <linux/sched.h> #include <asm/ia32.h> -/* Notebook: move the mmap code from sys_x86_64.c over here. */ +/* + * Top of mmap area (just below the process stack). + * + * Leave an at least ~128 MB hole. + */ +#define MIN_GAP (128*1024*1024) +#define MAX_GAP (TASK_SIZE/6*5) -void arch_pick_mmap_layout(struct mm_struct *mm) +static inline unsigned long mmap_base(void) +{ + unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur; + + if (gap < MIN_GAP) + gap = MIN_GAP; + else if (gap > MAX_GAP) + gap = MAX_GAP; + + return TASK_SIZE - (gap & PAGE_MASK); +} + +static inline int mmap_is_32(void) { #ifdef CONFIG_IA32_EMULATION - if (current_thread_info()->flags & _TIF_IA32) - return ia32_pick_mmap_layout(mm); + if (test_thread_flag(TIF_IA32)) + return 1; #endif - mm->mmap_base = TASK_UNMAPPED_BASE; + return 0; +} + +static inline int mmap_is_legacy(void) +{ + if (current->personality & ADDR_COMPAT_LAYOUT) + return 1; + + if (current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY) + return 1; + + return sysctl_legacy_va_layout; +} + +/* + * This function, called very early during the creation of a new + * process VM image, sets up which VM layout function to use: + */ +void arch_pick_mmap_layout(struct mm_struct *mm) +{ + int rnd = 0; if (current->flags & PF_RANDOMIZE) { /* - * Add 28bit randomness which is about 40bits of - * address space because mmap base has to be page - * aligned. or ~1/128 of the total user VM (total - * user address space is 47bits) + * Add 28bit randomness which is about 40bits of address space + * because mmap base has to be page aligned. + * or ~1/128 of the total user VM + * (total user address space is 47bits) */ - unsigned rnd = get_random_int() & 0xfffffff; + rnd = get_random_int() & 0xfffffff; + } - mm->mmap_base += ((unsigned long)rnd) << PAGE_SHIFT; + /* + * Fall back to the standard layout if the personality + * bit is set, or if the expected stack growth is unlimited: + */ + if (mmap_is_32()) { +#ifdef CONFIG_IA32_EMULATION + /* ia32_pick_mmap_layout has its own. */ + return ia32_pick_mmap_layout(mm); +#endif + } else if(mmap_is_legacy()) { + mm->mmap_base = TASK_UNMAPPED_BASE; + mm->get_unmapped_area = arch_get_unmapped_area; + mm->unmap_area = arch_unmap_area; + } else { + mm->mmap_base = mmap_base(); + mm->get_unmapped_area = arch_get_unmapped_area_topdown; + mm->unmap_area = arch_unmap_area_topdown; + if (current->flags & PF_RANDOMIZE) + rnd = -rnd; + } + if (current->flags & PF_RANDOMIZE) { + mm->mmap_base += ((long)rnd) << PAGE_SHIFT; } - mm->get_unmapped_area = arch_get_unmapped_area; - mm->unmap_area = arch_unmap_area; } - |