blob: 179a2c20b01f143a51a897d9b85e33198bf881a7 [file] [log] [blame]
/*
* flexible mmap layout support
*
* Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
* All Rights Reserved.
*
* 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
*
*
* Started by Ingo Molnar <mingo@elte.hu>
*/
#include <linux/personality.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/compat.h>
#include <linux/security.h>
#include <asm/pgalloc.h>
unsigned long mmap_rnd_mask;
unsigned long mmap_align_mask;
static unsigned long stack_maxrandom_size(void)
{
if (!(current->flags & PF_RANDOMIZE))
return 0;
if (current->personality & ADDR_NO_RANDOMIZE)
return 0;
return STACK_RND_MASK << PAGE_SHIFT;
}
/*
* Top of mmap area (just below the process stack).
*
* Leave at least a ~32 MB hole.
*/
#define MIN_GAP (32*1024*1024)
#define MAX_GAP (STACK_TOP/6*5)
static inline int mmap_is_legacy(void)
{
if (current->personality & ADDR_COMPAT_LAYOUT)
return 1;
if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
return 1;
return sysctl_legacy_va_layout;
}
static unsigned long mmap_rnd(void)
{
if (!(current->flags & PF_RANDOMIZE))
return 0;
if (is_32bit_task())
return (get_random_int() & 0x7ff) << PAGE_SHIFT;
else
return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT;
}
static unsigned long mmap_base_legacy(void)
{
return TASK_UNMAPPED_BASE + mmap_rnd();
}
static inline unsigned long mmap_base(void)
{
unsigned long gap = rlimit(RLIMIT_STACK);
if (gap < MIN_GAP)
gap = MIN_GAP;
else if (gap > MAX_GAP)
gap = MAX_GAP;
gap &= PAGE_MASK;
return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
}
unsigned long
arch_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
struct vm_unmapped_area_info info;
int do_color_align;
if (len > TASK_SIZE - mmap_min_addr)
return -ENOMEM;
if (flags & MAP_FIXED)
return addr;
if (addr) {
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
(!vma || addr + len <= vma->vm_start))
return addr;
}
do_color_align = 0;
if (filp || (flags & MAP_SHARED))
do_color_align = !is_32bit_task();
info.flags = 0;
info.length = len;
info.low_limit = mm->mmap_base;
info.high_limit = TASK_SIZE;
info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
info.align_offset = pgoff << PAGE_SHIFT;
return vm_unmapped_area(&info);
}
unsigned long
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
const unsigned long len, const unsigned long pgoff,
const unsigned long flags)
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
struct vm_unmapped_area_info info;
int do_color_align;
/* requested length too big for entire address space */
if (len > TASK_SIZE - mmap_min_addr)
return -ENOMEM;
if (flags & MAP_FIXED)
return addr;
/* requesting a specific address */
if (addr) {
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
(!vma || addr + len <= vma->vm_start))
return addr;
}
do_color_align = 0;
if (filp || (flags & MAP_SHARED))
do_color_align = !is_32bit_task();
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
info.low_limit = max(PAGE_SIZE, mmap_min_addr);
info.high_limit = mm->mmap_base;
info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0;
info.align_offset = pgoff << PAGE_SHIFT;
addr = vm_unmapped_area(&info);
/*
* A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario
* can happen with large stack limits and large mmap()
* allocations.
*/
if (addr & ~PAGE_MASK) {
VM_BUG_ON(addr != -ENOMEM);
info.flags = 0;
info.low_limit = TASK_UNMAPPED_BASE;
info.high_limit = TASK_SIZE;
addr = vm_unmapped_area(&info);
}
return addr;
}
unsigned long randomize_et_dyn(void)
{
unsigned long base;
base = STACK_TOP / 3 * 2;
if (!is_32bit_task())
/* Align to 4GB */
base &= ~((1UL << 32) - 1);
return base + mmap_rnd();
}
#ifndef CONFIG_64BIT
/*
* 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)
{
/*
* Fall back to the standard layout if the personality
* bit is set, or if the expected stack growth is unlimited:
*/
if (mmap_is_legacy()) {
mm->mmap_base = mmap_base_legacy();
mm->get_unmapped_area = arch_get_unmapped_area;
} else {
mm->mmap_base = mmap_base();
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
}
}
#else
int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
{
if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
return 0;
if (!(flags & MAP_FIXED))
addr = 0;
if ((addr + len) >= TASK_SIZE)
return crst_table_upgrade(current->mm, 1UL << 53);
return 0;
}
static unsigned long
s390_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
unsigned long area;
int rc;
area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
if (!(area & ~PAGE_MASK))
return area;
if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
/* Upgrade the page table to 4 levels and retry. */
rc = crst_table_upgrade(mm, 1UL << 53);
if (rc)
return (unsigned long) rc;
area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
}
return area;
}
static unsigned long
s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
const unsigned long len, const unsigned long pgoff,
const unsigned long flags)
{
struct mm_struct *mm = current->mm;
unsigned long area;
int rc;
area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
if (!(area & ~PAGE_MASK))
return area;
if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
/* Upgrade the page table to 4 levels and retry. */
rc = crst_table_upgrade(mm, 1UL << 53);
if (rc)
return (unsigned long) rc;
area = arch_get_unmapped_area_topdown(filp, addr, len,
pgoff, flags);
}
return area;
}
/*
* 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)
{
/*
* Fall back to the standard layout if the personality
* bit is set, or if the expected stack growth is unlimited:
*/
if (mmap_is_legacy()) {
mm->mmap_base = mmap_base_legacy();
mm->get_unmapped_area = s390_get_unmapped_area;
} else {
mm->mmap_base = mmap_base();
mm->get_unmapped_area = s390_get_unmapped_area_topdown;
}
}
static int __init setup_mmap_rnd(void)
{
struct cpuid cpu_id;
get_cpu_id(&cpu_id);
switch (cpu_id.machine) {
case 0x9672:
case 0x2064:
case 0x2066:
case 0x2084:
case 0x2086:
case 0x2094:
case 0x2096:
case 0x2097:
case 0x2098:
case 0x2817:
case 0x2818:
case 0x2827:
case 0x2828:
mmap_rnd_mask = 0x7ffUL;
mmap_align_mask = 0UL;
break;
case 0x2964: /* z13 */
default:
mmap_rnd_mask = 0x3ff80UL;
mmap_align_mask = 0x7fUL;
break;
}
return 0;
}
early_initcall(setup_mmap_rnd);
#endif