[linux-2.6-block.git] / arch / tile / mm / mmap.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;
}
Commit	Line	Data
867e359b CM	1	/*
	2	* Copyright 2010 Tilera Corporation. All Rights Reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public License
	6	* as published by the Free Software Foundation, version 2.
	7	*
	8	* This program is distributed in the hope that it will be useful, but
	9	* WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	11	* NON INFRINGEMENT. See the GNU General Public License for
	12	* more details.
	13	*
	14	* Taken from the i386 architecture and simplified.
	15	*/
	16
	17	#include <linux/mm.h>
	18	#include <linux/random.h>
	19	#include <linux/limits.h>
	20	#include <linux/sched.h>
	21	#include <linux/mman.h>
	22	#include <linux/compat.h>
	23
	24	/*
	25	* Top of mmap area (just below the process stack).
	26	*
	27	* Leave an at least ~128 MB hole.
	28	*/
	29	#define MIN_GAP (12810241024)
	30	#define MAX_GAP (TASK_SIZE/6*5)
	31
	32	static inline unsigned long mmap_base(struct mm_struct *mm)
	33	{
	34	unsigned long gap = rlimit(RLIMIT_STACK);
	35	unsigned long random_factor = 0;
	36
	37	if (current->flags & PF_RANDOMIZE)
	38	random_factor = get_random_int() % (1024*1024);
	39
	40	if (gap < MIN_GAP)
	41	gap = MIN_GAP;
	42	else if (gap > MAX_GAP)
	43	gap = MAX_GAP;
	44
	45	return PAGE_ALIGN(TASK_SIZE - gap - random_factor);
	46	}
	47
	48	/*
	49	* This function, called very early during the creation of a new
	50	* process VM image, sets up which VM layout function to use:
	51	*/
	52	void arch_pick_mmap_layout(struct mm_struct *mm)
	53	{
	54	#if !defined(__tilegx__)
	55	int is_32bit = 1;
	56	#elif defined(CONFIG_COMPAT)
	57	int is_32bit = is_compat_task();
	58	#else
	59	int is_32bit = 0;
	60	#endif
b2eca427 TL	61	unsigned long random_factor = 0UL;
	62
	63	/*
	64	* 8 bits of randomness in 32bit mmaps, 24 address space bits
	65	* 12 bits of randomness in 64bit mmaps, 28 address space bits
	66	*/
	67	if (current->flags & PF_RANDOMIZE) {
	68	if (is_32bit)
	69	random_factor = get_random_int() % (1<<8);
	70	else
	71	random_factor = get_random_int() % (1<<12);
	72
	73	random_factor <<= PAGE_SHIFT;
	74	}
867e359b CM	75
	76	/*
	77	* Use standard layout if the expected stack growth is unlimited
	78	* or we are running native 64 bits.
	79	*/
b2eca427 TL	80	if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) {
b2eca427 TL	81	mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
867e359b	82	mm->get_unmapped_area = arch_get_unmapped_area;
867e359b CM	83	} else {
	84	mm->mmap_base = mmap_base(mm);
	85	mm->get_unmapped_area = arch_get_unmapped_area_topdown;
867e359b CM	86	}
867e359b CM	87	}
b2eca427 TL	88
	89	unsigned long arch_randomize_brk(struct mm_struct *mm)
	90	{
	91	unsigned long range_end = mm->brk + 0x02000000;
	92	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
	93	}