[mirror_ubuntu-artful-kernel.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(void)
{
	if (current->personality & ADDR_COMPAT_LAYOUT)
		return 1;

	if (rlimit(RLIMIT_STACK) == 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)
{
	unsigned long gap = rlimit(RLIMIT_STACK);
	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;
	struct vm_unmapped_area_info info;

	if (unlikely(addr > mm->context.addr_limit &&
		     mm->context.addr_limit != TASK_SIZE))
		mm->context.addr_limit = TASK_SIZE;

	if (len > mm->task_size - mmap_min_addr)
		return -ENOMEM;

	if (flags & MAP_FIXED)
		return addr;

	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (mm->task_size - 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.align_mask = 0;

	if (unlikely(addr > DEFAULT_MAP_WINDOW))
		info.high_limit = mm->context.addr_limit;
	else
		info.high_limit = DEFAULT_MAP_WINDOW;

	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;
	struct vm_unmapped_area_info info;

	if (unlikely(addr > mm->context.addr_limit &&
		     mm->context.addr_limit != TASK_SIZE))
		mm->context.addr_limit = TASK_SIZE;

	/* requested length too big for entire address space */
	if (len > mm->task_size - mmap_min_addr)
		return -ENOMEM;

	if (flags & MAP_FIXED)
		return addr;

	/* requesting a specific address */
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (mm->task_size - 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;
	info.align_mask = 0;

	if (addr > DEFAULT_MAP_WINDOW)
		info.high_limit += mm->context.addr_limit - DEFAULT_MAP_WINDOW;

	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)
{
	if (mmap_is_legacy()) {
		mm->mmap_base = TASK_UNMAPPED_BASE;
		mm->get_unmapped_area = radix__arch_get_unmapped_area;
	} else {
		mm->mmap_base = mmap_base(random_factor);
		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);
#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)
{
	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);
	/*
	 * Fall back to the standard layout if the personality
	 * bit is set, or if the expected stack growth is unlimited:
	 */
	if (mmap_is_legacy()) {
		mm->mmap_base = TASK_UNMAPPED_BASE;
		mm->get_unmapped_area = arch_get_unmapped_area;
	} else {
		mm->mmap_base = mmap_base(random_factor);
		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
13a2cb36 AB	42	static inline int mmap_is_legacy(void)
	43	{
	44	if (current->personality & ADDR_COMPAT_LAYOUT)
	45	return 1;
	46
4bf936b9	47	if (rlimit(RLIMIT_STACK) == 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
ed632274	79	static inline unsigned long mmap_base(unsigned long rnd)
1da177e4	80	{
4bf936b9	81	unsigned long gap = rlimit(RLIMIT_STACK);
0a782dc3 RR	82	unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
	83
	84	/* Values close to RLIM_INFINITY can overflow. */
	85	if (gap + pad > gap)
	86	gap += pad;
1da177e4 LT	87
	88	if (gap < MIN_GAP)
	89	gap = MIN_GAP;
	90	else if (gap > MAX_GAP)
	91	gap = MAX_GAP;
	92
f4ea6dcb	93	return PAGE_ALIGN(DEFAULT_MAP_WINDOW - gap - rnd);
1da177e4 LT	94	}
1da177e4 LT	95
7a0eedee AK	96	#ifdef CONFIG_PPC_RADIX_MMU
	97	/*
	98	* Same function as generic code used only for radix, because we don't need to overload
	99	* the generic one. But we will have to duplicate, because hash select
	100	* HAVE_ARCH_UNMAPPED_AREA
	101	*/
	102	static unsigned long
	103	radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
	104	unsigned long len, unsigned long pgoff,
	105	unsigned long flags)
	106	{
	107	struct mm_struct *mm = current->mm;
	108	struct vm_area_struct *vma;
	109	struct vm_unmapped_area_info info;
	110
321f7d29 AK	111	if (unlikely(addr > mm->context.addr_limit &&
321f7d29 AK	112	mm->context.addr_limit != TASK_SIZE))
f4ea6dcb AK	113	mm->context.addr_limit = TASK_SIZE;
f4ea6dcb AK	114
be77e999	115	if (len > mm->task_size - mmap_min_addr)
7a0eedee AK	116	return -ENOMEM;
	117
	118	if (flags & MAP_FIXED)
	119	return addr;
	120
	121	if (addr) {
	122	addr = PAGE_ALIGN(addr);
	123	vma = find_vma(mm, addr);
be77e999	124	if (mm->task_size - len >= addr && addr >= mmap_min_addr &&
1be7107f	125	(!vma \|\| addr + len <= vm_start_gap(vma)))
7a0eedee AK	126	return addr;
	127	}
	128
	129	info.flags = 0;
	130	info.length = len;
	131	info.low_limit = mm->mmap_base;
7a0eedee	132	info.align_mask = 0;
f4ea6dcb AK	133
	134	if (unlikely(addr > DEFAULT_MAP_WINDOW))
	135	info.high_limit = mm->context.addr_limit;
	136	else
	137	info.high_limit = DEFAULT_MAP_WINDOW;
	138
7a0eedee AK	139	return vm_unmapped_area(&info);
	140	}
	141
	142	static unsigned long
	143	radix__arch_get_unmapped_area_topdown(struct file *filp,
	144	const unsigned long addr0,
	145	const unsigned long len,
	146	const unsigned long pgoff,
	147	const unsigned long flags)
	148	{
	149	struct vm_area_struct *vma;
	150	struct mm_struct *mm = current->mm;
	151	unsigned long addr = addr0;
	152	struct vm_unmapped_area_info info;
	153
321f7d29 AK	154	if (unlikely(addr > mm->context.addr_limit &&
321f7d29 AK	155	mm->context.addr_limit != TASK_SIZE))
f4ea6dcb AK	156	mm->context.addr_limit = TASK_SIZE;
f4ea6dcb AK	157
7a0eedee	158	/* requested length too big for entire address space */
be77e999	159	if (len > mm->task_size - mmap_min_addr)
7a0eedee AK	160	return -ENOMEM;
	161
	162	if (flags & MAP_FIXED)
	163	return addr;
	164
	165	/* requesting a specific address */
	166	if (addr) {
	167	addr = PAGE_ALIGN(addr);
	168	vma = find_vma(mm, addr);
be77e999	169	if (mm->task_size - len >= addr && addr >= mmap_min_addr &&
1be7107f	170	(!vma \|\| addr + len <= vm_start_gap(vma)))
7a0eedee AK	171	return addr;
	172	}
	173
	174	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	175	info.length = len;
	176	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
	177	info.high_limit = mm->mmap_base;
	178	info.align_mask = 0;
f4ea6dcb AK	179
	180	if (addr > DEFAULT_MAP_WINDOW)
	181	info.high_limit += mm->context.addr_limit - DEFAULT_MAP_WINDOW;
	182
7a0eedee	183	addr = vm_unmapped_area(&info);
f4ea6dcb AK	184	if (!(addr & ~PAGE_MASK))
	185	return addr;
	186	VM_BUG_ON(addr != -ENOMEM);
7a0eedee AK	187
	188	/*
	189	* A failed mmap() very likely causes application failure,
	190	* so fall back to the bottom-up function here. This scenario
	191	* can happen with large stack limits and large mmap()
	192	* allocations.
	193	*/
f4ea6dcb	194	return radix__arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
7a0eedee AK	195	}
	196
	197	static void radix__arch_pick_mmap_layout(struct mm_struct *mm,
	198	unsigned long random_factor)
	199	{
	200	if (mmap_is_legacy()) {
	201	mm->mmap_base = TASK_UNMAPPED_BASE;
	202	mm->get_unmapped_area = radix__arch_get_unmapped_area;
	203	} else {
	204	mm->mmap_base = mmap_base(random_factor);
	205	mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown;
	206	}
	207	}
	208	#else
	209	/* dummy */
	210	extern void radix__arch_pick_mmap_layout(struct mm_struct *mm,
	211	unsigned long random_factor);
	212	#endif
1da177e4 LT	213	/*
	214	* This function, called very early during the creation of a new
	215	* process VM image, sets up which VM layout function to use:
	216	*/
	217	void arch_pick_mmap_layout(struct mm_struct *mm)
	218	{
ed632274 KC	219	unsigned long random_factor = 0UL;
	220
	221	if (current->flags & PF_RANDOMIZE)
2b68f6ca	222	random_factor = arch_mmap_rnd();
ed632274	223
7a0eedee AK	224	if (radix_enabled())
7a0eedee AK	225	return radix__arch_pick_mmap_layout(mm, random_factor);
1da177e4 LT	226	/*
	227	* Fall back to the standard layout if the personality
	228	* bit is set, or if the expected stack growth is unlimited:
	229	*/
	230	if (mmap_is_legacy()) {
	231	mm->mmap_base = TASK_UNMAPPED_BASE;
	232	mm->get_unmapped_area = arch_get_unmapped_area;
1da177e4	233	} else {
ed632274	234	mm->mmap_base = mmap_base(random_factor);
1da177e4	235	mm->get_unmapped_area = arch_get_unmapped_area_topdown;
1da177e4 LT	236	}
1da177e4 LT	237	}