80 lines
2.3 KiB
C
80 lines
2.3 KiB
C
/*
|
|
* linux/arch/x86_64/ia32/mm/mmap.c
|
|
*
|
|
* flexible mmap layout support
|
|
*
|
|
* Based on the i386 version which was
|
|
*
|
|
* 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/random.h>
|
|
#include <linux/sched.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 = current->signal->rlim[RLIMIT_STACK].rlim_cur;
|
|
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 ia32_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 (sysctl_legacy_va_layout ||
|
|
(current->personality & ADDR_COMPAT_LAYOUT) ||
|
|
current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY) {
|
|
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);
|
|
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
|
|
mm->unmap_area = arch_unmap_area_topdown;
|
|
}
|
|
}
|