[linux-2.6-block.git] / arch / powerpc / mm / mmap.c

/*
 *  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/random.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
#include <linux/elf-randomize.h>
#include <linux/security.h>
#include <linux/mman.h>

/*
 * Top of mmap area (just below the process stack).
 *
 * Leave at least a ~128 MB hole.
 */
#define MIN_GAP (128*1024*1024)
#define MAX_GAP (TASK_SIZE/6*5)

static inline int mmap_is_legacy(struct rlimit *rlim_stack)
{
	if (current->personality & ADDR_COMPAT_LAYOUT)
		return 1;

	if (rlim_stack->rlim_cur == RLIM_INFINITY)
		return 1;

	return sysctl_legacy_va_layout;
}

unsigned long arch_mmap_rnd(void)
{
	unsigned long shift, rnd;

	shift = mmap_rnd_bits;
#ifdef CONFIG_COMPAT
	if (is_32bit_task())
		shift = mmap_rnd_compat_bits;
#endif
	rnd = get_random_long() % (1ul << shift);

	return rnd << PAGE_SHIFT;
}

static inline unsigned long stack_maxrandom_size(void)
{
	if (!(current->flags & PF_RANDOMIZE))
		return 0;

	/* 8MB for 32bit, 1GB for 64bit */
	if (is_32bit_task())
		return (1<<23);
	else
		return (1<<30);
}

static inline unsigned long mmap_base(unsigned long rnd,
				      struct rlimit *rlim_stack)
{
	unsigned long gap = rlim_stack->rlim_cur;
	unsigned long pad = stack_maxrandom_size() + stack_guard_gap;

	/* Values close to RLIM_INFINITY can overflow. */
	if (gap + pad > gap)
		gap += pad;

	if (gap < MIN_GAP)
		gap = MIN_GAP;
	else if (gap > MAX_GAP)
		gap = MAX_GAP;

	return PAGE_ALIGN(DEFAULT_MAP_WINDOW - gap - rnd);
}

#ifdef CONFIG_PPC_RADIX_MMU
/*
 * Same function as generic code used only for radix, because we don't need to overload
 * the generic one. But we will have to duplicate, because hash select
 * HAVE_ARCH_UNMAPPED_AREA
 */
static unsigned long
radix__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;
	int fixed = (flags & MAP_FIXED);
	unsigned long high_limit;
	struct vm_unmapped_area_info info;

	high_limit = DEFAULT_MAP_WINDOW;
	if (addr >= high_limit || (fixed && (addr + len > high_limit)))
		high_limit = TASK_SIZE;

	if (len > high_limit)
		return -ENOMEM;

	if (fixed) {
		if (addr > high_limit - len)
			return -ENOMEM;
		return addr;
	}

	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (high_limit - len >= addr && addr >= mmap_min_addr &&
		    (!vma || addr + len <= vm_start_gap(vma)))
			return addr;
	}

	info.flags = 0;
	info.length = len;
	info.low_limit = mm->mmap_base;
	info.high_limit = high_limit;
	info.align_mask = 0;

	return vm_unmapped_area(&info);
}

static unsigned long
radix__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;
	int fixed = (flags & MAP_FIXED);
	unsigned long high_limit;
	struct vm_unmapped_area_info info;

	high_limit = DEFAULT_MAP_WINDOW;
	if (addr >= high_limit || (fixed && (addr + len > high_limit)))
		high_limit = TASK_SIZE;

	if (len > high_limit)
		return -ENOMEM;

	if (fixed) {
		if (addr > high_limit - len)
			return -ENOMEM;
		return addr;
	}

	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (high_limit - len >= addr && addr >= mmap_min_addr &&
		    (!vma || addr + len <= vm_start_gap(vma)))
			return addr;
	}

	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
	info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);
	info.align_mask = 0;

	addr = vm_unmapped_area(&info);
	if (!(addr & ~PAGE_MASK))
		return addr;
	VM_BUG_ON(addr != -ENOMEM);

	/*
	 * 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.
	 */
	return radix__arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
}

static void radix__arch_pick_mmap_layout(struct mm_struct *mm,
					unsigned long random_factor,
					struct rlimit *rlim_stack)
{
	if (mmap_is_legacy(rlim_stack)) {
		mm->mmap_base = TASK_UNMAPPED_BASE;
		mm->get_unmapped_area = radix__arch_get_unmapped_area;
	} else {
		mm->mmap_base = mmap_base(random_factor, rlim_stack);
		mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown;
	}
}
#else
/* dummy */
extern void radix__arch_pick_mmap_layout(struct mm_struct *mm,
					unsigned long random_factor,
					struct rlimit *rlim_stack);
#endif
/*
 * 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, struct rlimit *rlim_stack)
{
	unsigned long random_factor = 0UL;

	if (current->flags & PF_RANDOMIZE)
		random_factor = arch_mmap_rnd();

	if (radix_enabled())
		return radix__arch_pick_mmap_layout(mm, random_factor,
						    rlim_stack);
	/*
	 * Fall back to the standard layout if the personality
	 * bit is set, or if the expected stack growth is unlimited:
	 */
	if (mmap_is_legacy(rlim_stack)) {
		mm->mmap_base = TASK_UNMAPPED_BASE;
		mm->get_unmapped_area = arch_get_unmapped_area;
	} else {
		mm->mmap_base = mmap_base(random_factor, rlim_stack);
		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
	}
}
Commit	Line	Data
1da177e4	1	/*
1da177e4 LT	2	* flexible mmap layout support
	3	*
	4	* Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
	5	* All Rights Reserved.
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License as published by
	9	* the Free Software Foundation; either version 2 of the License, or
	10	* (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	20	*
	21	*
	22	* Started by Ingo Molnar <mingo@elte.hu>
	23	*/
	24
	25	#include <linux/personality.h>
	26	#include <linux/mm.h>
9f14c42d	27	#include <linux/random.h>
3f07c014	28	#include <linux/sched/signal.h>
01042607	29	#include <linux/sched/mm.h>
7f92bc56	30	#include <linux/elf-randomize.h>
7a0eedee AK	31	#include <linux/security.h>
7a0eedee AK	32	#include <linux/mman.h>
1da177e4 LT	33
	34	/*
	35	* Top of mmap area (just below the process stack).
	36	*
0a782dc3	37	* Leave at least a ~128 MB hole.
1da177e4	38	*/
0a782dc3	39	#define MIN_GAP (12810241024)
1da177e4 LT	40	#define MAX_GAP (TASK_SIZE/6*5)
1da177e4 LT	41
8f2af155	42	static inline int mmap_is_legacy(struct rlimit *rlim_stack)
13a2cb36 AB	43	{
	44	if (current->personality & ADDR_COMPAT_LAYOUT)
	45	return 1;
	46
8f2af155	47	if (rlim_stack->rlim_cur == RLIM_INFINITY)
13a2cb36 AB	48	return 1;
	49
	50	return sysctl_legacy_va_layout;
	51	}
	52
2b68f6ca	53	unsigned long arch_mmap_rnd(void)
9f14c42d	54	{
9fea59bd	55	unsigned long shift, rnd;
ed632274	56
9fea59bd ME	57	shift = mmap_rnd_bits;
9fea59bd ME	58	#ifdef CONFIG_COMPAT
ed632274	59	if (is_32bit_task())
9fea59bd ME	60	shift = mmap_rnd_compat_bits;
9fea59bd ME	61	#endif
b409946b	62	rnd = get_random_long() % (1ul << shift);
9f14c42d	63
fa8cbaaf	64	return rnd << PAGE_SHIFT;
9f14c42d AB	65	}
9f14c42d AB	66
0a782dc3 RR	67	static inline unsigned long stack_maxrandom_size(void)
	68	{
	69	if (!(current->flags & PF_RANDOMIZE))
	70	return 0;
	71
	72	/* 8MB for 32bit, 1GB for 64bit */
	73	if (is_32bit_task())
	74	return (1<<23);
	75	else
	76	return (1<<30);
	77	}
	78
8f2af155 KC	79	static inline unsigned long mmap_base(unsigned long rnd,
8f2af155 KC	80	struct rlimit *rlim_stack)
1da177e4	81	{
8f2af155	82	unsigned long gap = rlim_stack->rlim_cur;
0a782dc3 RR	83	unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
	84
	85	/* Values close to RLIM_INFINITY can overflow. */
	86	if (gap + pad > gap)
	87	gap += pad;
1da177e4 LT	88
	89	if (gap < MIN_GAP)
	90	gap = MIN_GAP;
	91	else if (gap > MAX_GAP)
	92	gap = MAX_GAP;
	93
f4ea6dcb	94	return PAGE_ALIGN(DEFAULT_MAP_WINDOW - gap - rnd);
1da177e4 LT	95	}
1da177e4 LT	96
7a0eedee AK	97	#ifdef CONFIG_PPC_RADIX_MMU
	98	/*
	99	* Same function as generic code used only for radix, because we don't need to overload
	100	* the generic one. But we will have to duplicate, because hash select
	101	* HAVE_ARCH_UNMAPPED_AREA
	102	*/
	103	static unsigned long
	104	radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
	105	unsigned long len, unsigned long pgoff,
	106	unsigned long flags)
	107	{
	108	struct mm_struct *mm = current->mm;
	109	struct vm_area_struct *vma;
85e3f1ad NP	110	int fixed = (flags & MAP_FIXED);
85e3f1ad NP	111	unsigned long high_limit;
7a0eedee AK	112	struct vm_unmapped_area_info info;
7a0eedee AK	113
85e3f1ad NP	114	high_limit = DEFAULT_MAP_WINDOW;
	115	if (addr >= high_limit \|\| (fixed && (addr + len > high_limit)))
	116	high_limit = TASK_SIZE;
	117
	118	if (len > high_limit)
	119	return -ENOMEM;
4722476b	120
85e3f1ad NP	121	if (fixed) {
	122	if (addr > high_limit - len)
	123	return -ENOMEM;
7a0eedee	124	return addr;
4722476b	125	}
7a0eedee AK	126
	127	if (addr) {
	128	addr = PAGE_ALIGN(addr);
	129	vma = find_vma(mm, addr);
85e3f1ad	130	if (high_limit - len >= addr && addr >= mmap_min_addr &&
1be7107f	131	(!vma \|\| addr + len <= vm_start_gap(vma)))
7a0eedee AK	132	return addr;
	133	}
	134
	135	info.flags = 0;
	136	info.length = len;
	137	info.low_limit = mm->mmap_base;
85e3f1ad	138	info.high_limit = high_limit;
7a0eedee	139	info.align_mask = 0;
f4ea6dcb	140
7a0eedee AK	141	return vm_unmapped_area(&info);
	142	}
	143
	144	static unsigned long
	145	radix__arch_get_unmapped_area_topdown(struct file *filp,
	146	const unsigned long addr0,
	147	const unsigned long len,
	148	const unsigned long pgoff,
	149	const unsigned long flags)
	150	{
	151	struct vm_area_struct *vma;
	152	struct mm_struct *mm = current->mm;
	153	unsigned long addr = addr0;
85e3f1ad NP	154	int fixed = (flags & MAP_FIXED);
85e3f1ad NP	155	unsigned long high_limit;
7a0eedee AK	156	struct vm_unmapped_area_info info;
7a0eedee AK	157
85e3f1ad NP	158	high_limit = DEFAULT_MAP_WINDOW;
	159	if (addr >= high_limit \|\| (fixed && (addr + len > high_limit)))
	160	high_limit = TASK_SIZE;
	161
	162	if (len > high_limit)
	163	return -ENOMEM;
4722476b	164
85e3f1ad NP	165	if (fixed) {
	166	if (addr > high_limit - len)
	167	return -ENOMEM;
7a0eedee	168	return addr;
4722476b	169	}
7a0eedee	170
7a0eedee AK	171	if (addr) {
	172	addr = PAGE_ALIGN(addr);
	173	vma = find_vma(mm, addr);
85e3f1ad NP	174	if (high_limit - len >= addr && addr >= mmap_min_addr &&
85e3f1ad NP	175	(!vma \|\| addr + len <= vm_start_gap(vma)))
7a0eedee AK	176	return addr;
	177	}
	178
	179	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	180	info.length = len;
	181	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
85e3f1ad	182	info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);
7a0eedee	183	info.align_mask = 0;
f4ea6dcb	184
7a0eedee	185	addr = vm_unmapped_area(&info);
f4ea6dcb AK	186	if (!(addr & ~PAGE_MASK))
	187	return addr;
	188	VM_BUG_ON(addr != -ENOMEM);
7a0eedee AK	189
	190	/*
	191	* A failed mmap() very likely causes application failure,
	192	* so fall back to the bottom-up function here. This scenario
	193	* can happen with large stack limits and large mmap()
	194	* allocations.
	195	*/
f4ea6dcb	196	return radix__arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
7a0eedee AK	197	}
	198
	199	static void radix__arch_pick_mmap_layout(struct mm_struct *mm,
8f2af155 KC	200	unsigned long random_factor,
8f2af155 KC	201	struct rlimit *rlim_stack)
7a0eedee	202	{
8f2af155	203	if (mmap_is_legacy(rlim_stack)) {
7a0eedee AK	204	mm->mmap_base = TASK_UNMAPPED_BASE;
	205	mm->get_unmapped_area = radix__arch_get_unmapped_area;
	206	} else {
8f2af155	207	mm->mmap_base = mmap_base(random_factor, rlim_stack);
7a0eedee AK	208	mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown;
	209	}
	210	}
	211	#else
	212	/* dummy */
	213	extern void radix__arch_pick_mmap_layout(struct mm_struct *mm,
8f2af155 KC	214	unsigned long random_factor,
8f2af155 KC	215	struct rlimit *rlim_stack);
7a0eedee	216	#endif
1da177e4 LT	217	/*
	218	* This function, called very early during the creation of a new
	219	* process VM image, sets up which VM layout function to use:
	220	*/
8f2af155	221	void arch_pick_mmap_layout(struct mm_struct mm, struct rlimit rlim_stack)
1da177e4	222	{
ed632274 KC	223	unsigned long random_factor = 0UL;
	224
	225	if (current->flags & PF_RANDOMIZE)
2b68f6ca	226	random_factor = arch_mmap_rnd();
ed632274	227
7a0eedee	228	if (radix_enabled())
8f2af155 KC	229	return radix__arch_pick_mmap_layout(mm, random_factor,
8f2af155 KC	230	rlim_stack);
1da177e4 LT	231	/*
	232	* Fall back to the standard layout if the personality
	233	* bit is set, or if the expected stack growth is unlimited:
	234	*/
8f2af155	235	if (mmap_is_legacy(rlim_stack)) {
1da177e4 LT	236	mm->mmap_base = TASK_UNMAPPED_BASE;
1da177e4 LT	237	mm->get_unmapped_area = arch_get_unmapped_area;
1da177e4	238	} else {
8f2af155	239	mm->mmap_base = mmap_base(random_factor, rlim_stack);
1da177e4	240	mm->get_unmapped_area = arch_get_unmapped_area_topdown;
1da177e4 LT	241	}
1da177e4 LT	242	}