mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-20 10:44:23 +08:00
b2eca4274c
With this change, tile Linux now supports address-space layout randomization for shared objects, stack, heap and vdso. Acked-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Tony Lu <zlu@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
94 lines
2.5 KiB
C
94 lines
2.5 KiB
C
/*
|
|
* Copyright 2010 Tilera Corporation. 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, version 2.
|
|
*
|
|
* 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, GOOD TITLE or
|
|
* NON INFRINGEMENT. See the GNU General Public License for
|
|
* more details.
|
|
*
|
|
* Taken from the i386 architecture and simplified.
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/random.h>
|
|
#include <linux/limits.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/compat.h>
|
|
|
|
/*
|
|
* 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)
|
|
|
|
static inline unsigned long mmap_base(struct mm_struct *mm)
|
|
{
|
|
unsigned long gap = rlimit(RLIMIT_STACK);
|
|
unsigned long random_factor = 0;
|
|
|
|
if (current->flags & PF_RANDOMIZE)
|
|
random_factor = get_random_int() % (1024*1024);
|
|
|
|
if (gap < MIN_GAP)
|
|
gap = MIN_GAP;
|
|
else if (gap > MAX_GAP)
|
|
gap = MAX_GAP;
|
|
|
|
return PAGE_ALIGN(TASK_SIZE - gap - random_factor);
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
#if !defined(__tilegx__)
|
|
int is_32bit = 1;
|
|
#elif defined(CONFIG_COMPAT)
|
|
int is_32bit = is_compat_task();
|
|
#else
|
|
int is_32bit = 0;
|
|
#endif
|
|
unsigned long random_factor = 0UL;
|
|
|
|
/*
|
|
* 8 bits of randomness in 32bit mmaps, 24 address space bits
|
|
* 12 bits of randomness in 64bit mmaps, 28 address space bits
|
|
*/
|
|
if (current->flags & PF_RANDOMIZE) {
|
|
if (is_32bit)
|
|
random_factor = get_random_int() % (1<<8);
|
|
else
|
|
random_factor = get_random_int() % (1<<12);
|
|
|
|
random_factor <<= PAGE_SHIFT;
|
|
}
|
|
|
|
/*
|
|
* Use standard layout if the expected stack growth is unlimited
|
|
* or we are running native 64 bits.
|
|
*/
|
|
if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) {
|
|
mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
|
|
mm->get_unmapped_area = arch_get_unmapped_area;
|
|
} else {
|
|
mm->mmap_base = mmap_base(mm);
|
|
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
|
|
}
|
|
}
|
|
|
|
unsigned long arch_randomize_brk(struct mm_struct *mm)
|
|
{
|
|
unsigned long range_end = mm->brk + 0x02000000;
|
|
return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
|
|
}
|