[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / x86_64 / ia32 / mmap32.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;
	}
}
Commit	Line	Data
8817210d AK	1	/*
	2	* linux/arch/x86_64/ia32/mm/mmap.c
	3	*
	4	* flexible mmap layout support
	5	*
	6	* Based on the i386 version which was
	7	*
	8	* Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
	9	* All Rights Reserved.
	10	*
	11	* This program is free software; you can redistribute it and/or modify
	12	* it under the terms of the GNU General Public License as published by
	13	* the Free Software Foundation; either version 2 of the License, or
	14	* (at your option) any later version.
	15	*
	16	* This program is distributed in the hope that it will be useful,
	17	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	18	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	19	* GNU General Public License for more details.
	20	*
	21	* You should have received a copy of the GNU General Public License
	22	* along with this program; if not, write to the Free Software
	23	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	24	*
	25	*
	26	* Started by Ingo Molnar <mingo@elte.hu>
	27	*/
	28
	29	#include <linux/personality.h>
	30	#include <linux/mm.h>
	31	#include <linux/random.h>
e8edc6e0	32	#include <linux/sched.h>
8817210d AK	33
	34	/*
	35	* Top of mmap area (just below the process stack).
	36	*
	37	* Leave an at least ~128 MB hole.
	38	*/
	39	#define MIN_GAP (12810241024)
	40	#define MAX_GAP (TASK_SIZE/6*5)
	41
	42	static inline unsigned long mmap_base(struct mm_struct *mm)
	43	{
	44	unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;
	45	unsigned long random_factor = 0;
	46
	47	if (current->flags & PF_RANDOMIZE)
	48	random_factor = get_random_int() % (1024*1024);
	49
	50	if (gap < MIN_GAP)
	51	gap = MIN_GAP;
	52	else if (gap > MAX_GAP)
	53	gap = MAX_GAP;
	54
	55	return PAGE_ALIGN(TASK_SIZE - gap - random_factor);
	56	}
	57
	58	/*
	59	* This function, called very early during the creation of a new
	60	* process VM image, sets up which VM layout function to use:
	61	*/
	62	void ia32_pick_mmap_layout(struct mm_struct *mm)
	63	{
	64	/*
	65	* Fall back to the standard layout if the personality
	66	* bit is set, or if the expected stack growth is unlimited:
	67	*/
	68	if (sysctl_legacy_va_layout \|\|
	69	(current->personality & ADDR_COMPAT_LAYOUT) \|\|
	70	current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY) {
	71	mm->mmap_base = TASK_UNMAPPED_BASE;
	72	mm->get_unmapped_area = arch_get_unmapped_area;
	73	mm->unmap_area = arch_unmap_area;
	74	} else {
	75	mm->mmap_base = mmap_base(mm);
	76	mm->get_unmapped_area = arch_get_unmapped_area_topdown;
	77	mm->unmap_area = arch_unmap_area_topdown;
	78	}
	79	}