[deliverable/linux.git] / arch / arm64 / mm / mmap.c

/*
 * Based on arch/arm/mm/mmap.c
 *
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <linux/elf.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/export.h>
#include <linux/shm.h>
#include <linux/sched.h>
#include <linux/io.h>
#include <linux/personality.h>
#include <linux/random.h>

#include <asm/cputype.h>

/*
 * Leave enough space between the mmap area and the stack to honour ulimit in
 * the face of randomisation.
 */
#define MIN_GAP (SZ_128M + ((STACK_RND_MASK << PAGE_SHIFT) + 1))
#define MAX_GAP	(STACK_TOP/6*5)

static 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;
}

static unsigned long mmap_rnd(void)
{
	unsigned long rnd = 0;

	if (current->flags & PF_RANDOMIZE)
		rnd = (long)get_random_int() & STACK_RND_MASK;

	return rnd << PAGE_SHIFT;
}

static unsigned long mmap_base(void)
{
	unsigned long gap = rlimit(RLIMIT_STACK);

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

	return PAGE_ALIGN(STACK_TOP - gap - mmap_rnd());
}

/*
 * 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)
{
	/*
	 * 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();
		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
	}
}
EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);


/*
 * You really shouldn't be using read() or write() on /dev/mem.  This might go
 * away in the future.
 */
int valid_phys_addr_range(phys_addr_t addr, size_t size)
{
	if (addr < PHYS_OFFSET)
		return 0;
	if (addr + size > __pa(high_memory - 1) + 1)
		return 0;

	return 1;
}

/*
 * Do not allow /dev/mem mappings beyond the supported physical range.
 */
int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
{
	return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
}

#ifdef CONFIG_STRICT_DEVMEM

#include <linux/ioport.h>

/*
 * devmem_is_allowed() checks to see if /dev/mem access to a certain address
 * is valid. The argument is a physical page number.  We mimic x86 here by
 * disallowing access to system RAM as well as device-exclusive MMIO regions.
 * This effectively disable read()/write() on /dev/mem.
 */
int devmem_is_allowed(unsigned long pfn)
{
	if (iomem_is_exclusive(pfn << PAGE_SHIFT))
		return 0;
	if (!page_is_ram(pfn))
		return 1;
	return 0;
}

#endif
Commit	Line	Data
1d18c47c CM	1	/*
	2	* Based on arch/arm/mm/mmap.c
	3	*
	4	* Copyright (C) 2012 ARM Ltd.
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	17	*/
	18
	19	#include <linux/elf.h>
	20	#include <linux/fs.h>
	21	#include <linux/mm.h>
	22	#include <linux/mman.h>
	23	#include <linux/export.h>
	24	#include <linux/shm.h>
	25	#include <linux/sched.h>
	26	#include <linux/io.h>
	27	#include <linux/personality.h>
	28	#include <linux/random.h>
	29
	30	#include <asm/cputype.h>
	31
	32	/*
	33	* Leave enough space between the mmap area and the stack to honour ulimit in
	34	* the face of randomisation.
	35	*/
	36	#define MIN_GAP (SZ_128M + ((STACK_RND_MASK << PAGE_SHIFT) + 1))
	37	#define MAX_GAP (STACK_TOP/6*5)
	38
	39	static int mmap_is_legacy(void)
	40	{
	41	if (current->personality & ADDR_COMPAT_LAYOUT)
	42	return 1;
	43
	44	if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
	45	return 1;
	46
	47	return sysctl_legacy_va_layout;
	48	}
	49
1d18c47c CM	50	static unsigned long mmap_rnd(void)
	51	{
	52	unsigned long rnd = 0;
	53
	54	if (current->flags & PF_RANDOMIZE)
d6c763af	55	rnd = (long)get_random_int() & STACK_RND_MASK;
1d18c47c	56
d6c763af	57	return rnd << PAGE_SHIFT;
1d18c47c CM	58	}
	59
	60	static unsigned long mmap_base(void)
	61	{
	62	unsigned long gap = rlimit(RLIMIT_STACK);
	63
	64	if (gap < MIN_GAP)
	65	gap = MIN_GAP;
	66	else if (gap > MAX_GAP)
	67	gap = MAX_GAP;
	68
	69	return PAGE_ALIGN(STACK_TOP - gap - mmap_rnd());
	70	}
	71
	72	/*
	73	* This function, called very early during the creation of a new process VM
	74	* image, sets up which VM layout function to use:
	75	*/
	76	void arch_pick_mmap_layout(struct mm_struct *mm)
	77	{
	78	/*
	79	* Fall back to the standard layout if the personality bit is set, or
	80	* if the expected stack growth is unlimited:
	81	*/
	82	if (mmap_is_legacy()) {
	83	mm->mmap_base = TASK_UNMAPPED_BASE;
	84	mm->get_unmapped_area = arch_get_unmapped_area;
1d18c47c CM	85	} else {
	86	mm->mmap_base = mmap_base();
	87	mm->get_unmapped_area = arch_get_unmapped_area_topdown;
1d18c47c CM	88	}
	89	}
	90	EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
	91
	92
	93	/*
	94	* You really shouldn't be using read() or write() on /dev/mem. This might go
	95	* away in the future.
	96	*/
097cbd8d	97	int valid_phys_addr_range(phys_addr_t addr, size_t size)
1d18c47c CM	98	{
	99	if (addr < PHYS_OFFSET)
	100	return 0;
	101	if (addr + size > __pa(high_memory - 1) + 1)
	102	return 0;
	103
	104	return 1;
	105	}
	106
	107	/*
	108	* Do not allow /dev/mem mappings beyond the supported physical range.
	109	*/
	110	int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
	111	{
	112	return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
	113	}
	114
	115	#ifdef CONFIG_STRICT_DEVMEM
	116
	117	#include <linux/ioport.h>
	118
	119	/*
	120	* devmem_is_allowed() checks to see if /dev/mem access to a certain address
	121	* is valid. The argument is a physical page number. We mimic x86 here by
	122	* disallowing access to system RAM as well as device-exclusive MMIO regions.
	123	* This effectively disable read()/write() on /dev/mem.
	124	*/
	125	int devmem_is_allowed(unsigned long pfn)
	126	{
	127	if (iomem_is_exclusive(pfn << PAGE_SHIFT))
	128	return 0;
	129	if (!page_is_ram(pfn))
	130	return 1;
	131	return 0;
	132	}
	133
	134	#endif