[mirror_ubuntu-zesty-kernel.git] / mm / util.c

#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/compiler.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/security.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/mman.h>
#include <linux/hugetlb.h>
#include <linux/vmalloc.h>

#include <asm/sections.h>
#include <asm/uaccess.h>

#include "internal.h"

static inline int is_kernel_rodata(unsigned long addr)
{
	return addr >= (unsigned long)__start_rodata &&
		addr < (unsigned long)__end_rodata;
}

/**
 * kfree_const - conditionally free memory
 * @x: pointer to the memory
 *
 * Function calls kfree only if @x is not in .rodata section.
 */
void kfree_const(const void *x)
{
	if (!is_kernel_rodata((unsigned long)x))
		kfree(x);
}
EXPORT_SYMBOL(kfree_const);

/**
 * kstrdup - allocate space for and copy an existing string
 * @s: the string to duplicate
 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 */
char *kstrdup(const char *s, gfp_t gfp)
{
	size_t len;
	char *buf;

	if (!s)
		return NULL;

	len = strlen(s) + 1;
	buf = kmalloc_track_caller(len, gfp);
	if (buf)
		memcpy(buf, s, len);
	return buf;
}
EXPORT_SYMBOL(kstrdup);

/**
 * kstrdup_const - conditionally duplicate an existing const string
 * @s: the string to duplicate
 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 *
 * Function returns source string if it is in .rodata section otherwise it
 * fallbacks to kstrdup.
 * Strings allocated by kstrdup_const should be freed by kfree_const.
 */
const char *kstrdup_const(const char *s, gfp_t gfp)
{
	if (is_kernel_rodata((unsigned long)s))
		return s;

	return kstrdup(s, gfp);
}
EXPORT_SYMBOL(kstrdup_const);

/**
 * kstrndup - allocate space for and copy an existing string
 * @s: the string to duplicate
 * @max: read at most @max chars from @s
 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 */
char *kstrndup(const char *s, size_t max, gfp_t gfp)
{
	size_t len;
	char *buf;

	if (!s)
		return NULL;

	len = strnlen(s, max);
	buf = kmalloc_track_caller(len+1, gfp);
	if (buf) {
		memcpy(buf, s, len);
		buf[len] = '\0';
	}
	return buf;
}
EXPORT_SYMBOL(kstrndup);

/**
 * kmemdup - duplicate region of memory
 *
 * @src: memory region to duplicate
 * @len: memory region length
 * @gfp: GFP mask to use
 */
void *kmemdup(const void *src, size_t len, gfp_t gfp)
{
	void *p;

	p = kmalloc_track_caller(len, gfp);
	if (p)
		memcpy(p, src, len);
	return p;
}
EXPORT_SYMBOL(kmemdup);

/**
 * memdup_user - duplicate memory region from user space
 *
 * @src: source address in user space
 * @len: number of bytes to copy
 *
 * Returns an ERR_PTR() on failure.
 */
void *memdup_user(const void __user *src, size_t len)
{
	void *p;

	/*
	 * Always use GFP_KERNEL, since copy_from_user() can sleep and
	 * cause pagefault, which makes it pointless to use GFP_NOFS
	 * or GFP_ATOMIC.
	 */
	p = kmalloc_track_caller(len, GFP_KERNEL);
	if (!p)
		return ERR_PTR(-ENOMEM);

	if (copy_from_user(p, src, len)) {
		kfree(p);
		return ERR_PTR(-EFAULT);
	}

	return p;
}
EXPORT_SYMBOL(memdup_user);

/*
 * strndup_user - duplicate an existing string from user space
 * @s: The string to duplicate
 * @n: Maximum number of bytes to copy, including the trailing NUL.
 */
char *strndup_user(const char __user *s, long n)
{
	char *p;
	long length;

	length = strnlen_user(s, n);

	if (!length)
		return ERR_PTR(-EFAULT);

	if (length > n)
		return ERR_PTR(-EINVAL);

	p = memdup_user(s, length);

	if (IS_ERR(p))
		return p;

	p[length - 1] = '\0';

	return p;
}
EXPORT_SYMBOL(strndup_user);

/**
 * memdup_user_nul - duplicate memory region from user space and NUL-terminate
 *
 * @src: source address in user space
 * @len: number of bytes to copy
 *
 * Returns an ERR_PTR() on failure.
 */
void *memdup_user_nul(const void __user *src, size_t len)
{
	char *p;

	/*
	 * Always use GFP_KERNEL, since copy_from_user() can sleep and
	 * cause pagefault, which makes it pointless to use GFP_NOFS
	 * or GFP_ATOMIC.
	 */
	p = kmalloc_track_caller(len + 1, GFP_KERNEL);
	if (!p)
		return ERR_PTR(-ENOMEM);

	if (copy_from_user(p, src, len)) {
		kfree(p);
		return ERR_PTR(-EFAULT);
	}
	p[len] = '\0';

	return p;
}
EXPORT_SYMBOL(memdup_user_nul);

void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
		struct vm_area_struct *prev, struct rb_node *rb_parent)
{
	struct vm_area_struct *next;

	vma->vm_prev = prev;
	if (prev) {
		next = prev->vm_next;
		prev->vm_next = vma;
	} else {
		mm->mmap = vma;
		if (rb_parent)
			next = rb_entry(rb_parent,
					struct vm_area_struct, vm_rb);
		else
			next = NULL;
	}
	vma->vm_next = next;
	if (next)
		next->vm_prev = vma;
}

/* Check if the vma is being used as a stack by this task */
static int vm_is_stack_for_task(struct task_struct *t,
				struct vm_area_struct *vma)
{
	return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
}

/*
 * Check if the vma is being used as a stack.
 * If is_group is non-zero, check in the entire thread group or else
 * just check in the current task. Returns the task_struct of the task
 * that the vma is stack for. Must be called under rcu_read_lock().
 */
struct task_struct *task_of_stack(struct task_struct *task,
				struct vm_area_struct *vma, bool in_group)
{
	if (vm_is_stack_for_task(task, vma))
		return task;

	if (in_group) {
		struct task_struct *t;

		for_each_thread(task, t) {
			if (vm_is_stack_for_task(t, vma))
				return t;
		}
	}

	return NULL;
}

#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
void arch_pick_mmap_layout(struct mm_struct *mm)
{
	mm->mmap_base = TASK_UNMAPPED_BASE;
	mm->get_unmapped_area = arch_get_unmapped_area;
}
#endif

/*
 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
 * back to the regular GUP.
 * If the architecture not support this function, simply return with no
 * page pinned
 */
int __weak __get_user_pages_fast(unsigned long start,
				 int nr_pages, int write, struct page **pages)
{
	return 0;
}
EXPORT_SYMBOL_GPL(__get_user_pages_fast);

/**
 * get_user_pages_fast() - pin user pages in memory
 * @start:	starting user address
 * @nr_pages:	number of pages from start to pin
 * @write:	whether pages will be written to
 * @pages:	array that receives pointers to the pages pinned.
 *		Should be at least nr_pages long.
 *
 * Returns number of pages pinned. This may be fewer than the number
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
 * were pinned, returns -errno.
 *
 * get_user_pages_fast provides equivalent functionality to get_user_pages,
 * operating on current and current->mm, with force=0 and vma=NULL. However
 * unlike get_user_pages, it must be called without mmap_sem held.
 *
 * get_user_pages_fast may take mmap_sem and page table locks, so no
 * assumptions can be made about lack of locking. get_user_pages_fast is to be
 * implemented in a way that is advantageous (vs get_user_pages()) when the
 * user memory area is already faulted in and present in ptes. However if the
 * pages have to be faulted in, it may turn out to be slightly slower so
 * callers need to carefully consider what to use. On many architectures,
 * get_user_pages_fast simply falls back to get_user_pages.
 */
int __weak get_user_pages_fast(unsigned long start,
				int nr_pages, int write, struct page **pages)
{
	struct mm_struct *mm = current->mm;
	return get_user_pages_unlocked(current, mm, start, nr_pages,
				       write, 0, pages);
}
EXPORT_SYMBOL_GPL(get_user_pages_fast);

unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
	unsigned long len, unsigned long prot,
	unsigned long flag, unsigned long pgoff)
{
	unsigned long ret;
	struct mm_struct *mm = current->mm;
	unsigned long populate;

	ret = security_mmap_file(file, prot, flag);
	if (!ret) {
		down_write(&mm->mmap_sem);
		ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
				    &populate);
		up_write(&mm->mmap_sem);
		if (populate)
			mm_populate(ret, populate);
	}
	return ret;
}

unsigned long vm_mmap(struct file *file, unsigned long addr,
	unsigned long len, unsigned long prot,
	unsigned long flag, unsigned long offset)
{
	if (unlikely(offset + PAGE_ALIGN(len) < offset))
		return -EINVAL;
	if (unlikely(offset_in_page(offset)))
		return -EINVAL;

	return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
}
EXPORT_SYMBOL(vm_mmap);

void kvfree(const void *addr)
{
	if (is_vmalloc_addr(addr))
		vfree(addr);
	else
		kfree(addr);
}
EXPORT_SYMBOL(kvfree);

static inline void *__page_rmapping(struct page *page)
{
	unsigned long mapping;

	mapping = (unsigned long)page->mapping;
	mapping &= ~PAGE_MAPPING_FLAGS;

	return (void *)mapping;
}

/* Neutral page->mapping pointer to address_space or anon_vma or other */
void *page_rmapping(struct page *page)
{
	page = compound_head(page);
	return __page_rmapping(page);
}

struct anon_vma *page_anon_vma(struct page *page)
{
	unsigned long mapping;

	page = compound_head(page);
	mapping = (unsigned long)page->mapping;
	if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
		return NULL;
	return __page_rmapping(page);
}

struct address_space *page_mapping(struct page *page)
{
	struct address_space *mapping;

	page = compound_head(page);

	/* This happens if someone calls flush_dcache_page on slab page */
	if (unlikely(PageSlab(page)))
		return NULL;

	if (unlikely(PageSwapCache(page))) {
		swp_entry_t entry;

		entry.val = page_private(page);
		return swap_address_space(entry);
	}

	mapping = page->mapping;
	if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
		return NULL;
	return mapping;
}

/* Slow path of page_mapcount() for compound pages */
int __page_mapcount(struct page *page)
{
	int ret;

	ret = atomic_read(&page->_mapcount) + 1;
	page = compound_head(page);
	ret += atomic_read(compound_mapcount_ptr(page)) + 1;
	if (PageDoubleMap(page))
		ret--;
	return ret;
}
EXPORT_SYMBOL_GPL(__page_mapcount);

int overcommit_ratio_handler(struct ctl_table *table, int write,
			     void __user *buffer, size_t *lenp,
			     loff_t *ppos)
{
	int ret;

	ret = proc_dointvec(table, write, buffer, lenp, ppos);
	if (ret == 0 && write)
		sysctl_overcommit_kbytes = 0;
	return ret;
}

int overcommit_kbytes_handler(struct ctl_table *table, int write,
			     void __user *buffer, size_t *lenp,
			     loff_t *ppos)
{
	int ret;

	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
	if (ret == 0 && write)
		sysctl_overcommit_ratio = 0;
	return ret;
}

/*
 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
 */
unsigned long vm_commit_limit(void)
{
	unsigned long allowed;

	if (sysctl_overcommit_kbytes)
		allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
	else
		allowed = ((totalram_pages - hugetlb_total_pages())
			   * sysctl_overcommit_ratio / 100);
	allowed += total_swap_pages;

	return allowed;
}

/**
 * get_cmdline() - copy the cmdline value to a buffer.
 * @task:     the task whose cmdline value to copy.
 * @buffer:   the buffer to copy to.
 * @buflen:   the length of the buffer. Larger cmdline values are truncated
 *            to this length.
 * Returns the size of the cmdline field copied. Note that the copy does
 * not guarantee an ending NULL byte.
 */
int get_cmdline(struct task_struct *task, char *buffer, int buflen)
{
	int res = 0;
	unsigned int len;
	struct mm_struct *mm = get_task_mm(task);
	if (!mm)
		goto out;
	if (!mm->arg_end)
		goto out_mm;	/* Shh! No looking before we're done */

	len = mm->arg_end - mm->arg_start;

	if (len > buflen)
		len = buflen;

	res = access_process_vm(task, mm->arg_start, buffer, len, 0);

	/*
	 * If the nul at the end of args has been overwritten, then
	 * assume application is using setproctitle(3).
	 */
	if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
		len = strnlen(buffer, res);
		if (len < res) {
			res = len;
		} else {
			len = mm->env_end - mm->env_start;
			if (len > buflen - res)
				len = buflen - res;
			res += access_process_vm(task, mm->env_start,
						 buffer+res, len, 0);
			res = strnlen(buffer, res);
		}
	}
out_mm:
	mmput(mm);
out:
	return res;
}
Commit	Line	Data
16d69265	1	#include <linux/mm.h>
30992c97 MM	2	#include <linux/slab.h>
30992c97 MM	3	#include <linux/string.h>
3b32123d	4	#include <linux/compiler.h>
b95f1b31	5	#include <linux/export.h>
96840aa0	6	#include <linux/err.h>
3b8f14b4	7	#include <linux/sched.h>
eb36c587	8	#include <linux/security.h>
9800339b	9	#include <linux/swap.h>
33806f06	10	#include <linux/swapops.h>
00619bcc JM	11	#include <linux/mman.h>
00619bcc JM	12	#include <linux/hugetlb.h>
39f1f78d	13	#include <linux/vmalloc.h>
00619bcc	14
a4bb1e43	15	#include <asm/sections.h>
96840aa0	16	#include <asm/uaccess.h>
30992c97	17
6038def0 NK	18	#include "internal.h"
6038def0 NK	19
a4bb1e43 AH	20	static inline int is_kernel_rodata(unsigned long addr)
	21	{
	22	return addr >= (unsigned long)__start_rodata &&
	23	addr < (unsigned long)__end_rodata;
	24	}
	25
	26	/**
	27	* kfree_const - conditionally free memory
	28	* @x: pointer to the memory
	29	*
	30	* Function calls kfree only if @x is not in .rodata section.
	31	*/
	32	void kfree_const(const void *x)
	33	{
	34	if (!is_kernel_rodata((unsigned long)x))
	35	kfree(x);
	36	}
	37	EXPORT_SYMBOL(kfree_const);
	38
30992c97	39	/**
30992c97	40	* kstrdup - allocate space for and copy an existing string
30992c97 MM	41	* @s: the string to duplicate
	42	* @gfp: the GFP mask used in the kmalloc() call when allocating memory
	43	*/
	44	char kstrdup(const char s, gfp_t gfp)
	45	{
	46	size_t len;
	47	char *buf;
	48
	49	if (!s)
	50	return NULL;
	51
	52	len = strlen(s) + 1;
1d2c8eea	53	buf = kmalloc_track_caller(len, gfp);
30992c97 MM	54	if (buf)
	55	memcpy(buf, s, len);
	56	return buf;
	57	}
	58	EXPORT_SYMBOL(kstrdup);
96840aa0	59
a4bb1e43 AH	60	/**
	61	* kstrdup_const - conditionally duplicate an existing const string
	62	* @s: the string to duplicate
	63	* @gfp: the GFP mask used in the kmalloc() call when allocating memory
	64	*
	65	* Function returns source string if it is in .rodata section otherwise it
	66	* fallbacks to kstrdup.
	67	* Strings allocated by kstrdup_const should be freed by kfree_const.
	68	*/
	69	const char kstrdup_const(const char s, gfp_t gfp)
	70	{
	71	if (is_kernel_rodata((unsigned long)s))
	72	return s;
	73
	74	return kstrdup(s, gfp);
	75	}
	76	EXPORT_SYMBOL(kstrdup_const);
	77
1e66df3e JF	78	/**
	79	* kstrndup - allocate space for and copy an existing string
	80	* @s: the string to duplicate
	81	* @max: read at most @max chars from @s
	82	* @gfp: the GFP mask used in the kmalloc() call when allocating memory
	83	*/
	84	char kstrndup(const char s, size_t max, gfp_t gfp)
	85	{
	86	size_t len;
	87	char *buf;
	88
	89	if (!s)
	90	return NULL;
	91
	92	len = strnlen(s, max);
	93	buf = kmalloc_track_caller(len+1, gfp);
	94	if (buf) {
	95	memcpy(buf, s, len);
	96	buf[len] = '\0';
	97	}
	98	return buf;
	99	}
	100	EXPORT_SYMBOL(kstrndup);
	101
1a2f67b4 AD	102	/**
	103	* kmemdup - duplicate region of memory
	104	*
	105	* @src: memory region to duplicate
	106	* @len: memory region length
	107	* @gfp: GFP mask to use
	108	*/
	109	void kmemdup(const void src, size_t len, gfp_t gfp)
	110	{
	111	void *p;
	112
1d2c8eea	113	p = kmalloc_track_caller(len, gfp);
1a2f67b4 AD	114	if (p)
	115	memcpy(p, src, len);
	116	return p;
	117	}
	118	EXPORT_SYMBOL(kmemdup);
	119
610a77e0 LZ	120	/**
	121	* memdup_user - duplicate memory region from user space
	122	*
	123	* @src: source address in user space
	124	* @len: number of bytes to copy
	125	*
	126	* Returns an ERR_PTR() on failure.
	127	*/
	128	void memdup_user(const void __user src, size_t len)
	129	{
	130	void *p;
	131
	132	/*
	133	* Always use GFP_KERNEL, since copy_from_user() can sleep and
	134	* cause pagefault, which makes it pointless to use GFP_NOFS
	135	* or GFP_ATOMIC.
	136	*/
	137	p = kmalloc_track_caller(len, GFP_KERNEL);
	138	if (!p)
	139	return ERR_PTR(-ENOMEM);
	140
	141	if (copy_from_user(p, src, len)) {
	142	kfree(p);
	143	return ERR_PTR(-EFAULT);
	144	}
	145
	146	return p;
	147	}
	148	EXPORT_SYMBOL(memdup_user);
	149
96840aa0 DA	150	/*
96840aa0 DA	151	* strndup_user - duplicate an existing string from user space
96840aa0 DA	152	* @s: The string to duplicate
	153	* @n: Maximum number of bytes to copy, including the trailing NUL.
	154	*/
	155	char strndup_user(const char __user s, long n)
	156	{
	157	char *p;
	158	long length;
	159
	160	length = strnlen_user(s, n);
	161
	162	if (!length)
	163	return ERR_PTR(-EFAULT);
	164
	165	if (length > n)
	166	return ERR_PTR(-EINVAL);
	167
90d74045	168	p = memdup_user(s, length);
96840aa0	169
90d74045 JL	170	if (IS_ERR(p))
90d74045 JL	171	return p;
96840aa0 DA	172
	173	p[length - 1] = '\0';
	174
	175	return p;
	176	}
	177	EXPORT_SYMBOL(strndup_user);
16d69265	178
e9d408e1 AV	179	/**
	180	* memdup_user_nul - duplicate memory region from user space and NUL-terminate
	181	*
	182	* @src: source address in user space
	183	* @len: number of bytes to copy
	184	*
	185	* Returns an ERR_PTR() on failure.
	186	*/
	187	void memdup_user_nul(const void __user src, size_t len)
	188	{
	189	char *p;
	190
	191	/*
	192	* Always use GFP_KERNEL, since copy_from_user() can sleep and
	193	* cause pagefault, which makes it pointless to use GFP_NOFS
	194	* or GFP_ATOMIC.
	195	*/
	196	p = kmalloc_track_caller(len + 1, GFP_KERNEL);
	197	if (!p)
	198	return ERR_PTR(-ENOMEM);
	199
	200	if (copy_from_user(p, src, len)) {
	201	kfree(p);
	202	return ERR_PTR(-EFAULT);
	203	}
	204	p[len] = '\0';
	205
	206	return p;
	207	}
	208	EXPORT_SYMBOL(memdup_user_nul);
	209
6038def0 NK	210	void __vma_link_list(struct mm_struct mm, struct vm_area_struct vma,
	211	struct vm_area_struct prev, struct rb_node rb_parent)
	212	{
	213	struct vm_area_struct *next;
	214
	215	vma->vm_prev = prev;
	216	if (prev) {
	217	next = prev->vm_next;
	218	prev->vm_next = vma;
	219	} else {
	220	mm->mmap = vma;
	221	if (rb_parent)
	222	next = rb_entry(rb_parent,
	223	struct vm_area_struct, vm_rb);
	224	else
	225	next = NULL;
	226	}
	227	vma->vm_next = next;
	228	if (next)
	229	next->vm_prev = vma;
	230	}
	231
b7643757 SP	232	/* Check if the vma is being used as a stack by this task */
	233	static int vm_is_stack_for_task(struct task_struct *t,
	234	struct vm_area_struct *vma)
	235	{
	236	return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
	237	}
	238
	239	/*
	240	* Check if the vma is being used as a stack.
	241	* If is_group is non-zero, check in the entire thread group or else
58cb6548 ON	242	* just check in the current task. Returns the task_struct of the task
58cb6548 ON	243	* that the vma is stack for. Must be called under rcu_read_lock().
b7643757	244	*/
58cb6548 ON	245	struct task_struct task_of_stack(struct task_struct task,
58cb6548 ON	246	struct vm_area_struct *vma, bool in_group)
b7643757	247	{
b7643757	248	if (vm_is_stack_for_task(task, vma))
58cb6548	249	return task;
b7643757 SP	250
	251	if (in_group) {
	252	struct task_struct *t;
b7643757	253
4449a51a	254	for_each_thread(task, t) {
58cb6548 ON	255	if (vm_is_stack_for_task(t, vma))
58cb6548 ON	256	return t;
4449a51a	257	}
b7643757 SP	258	}
b7643757 SP	259
58cb6548	260	return NULL;
b7643757 SP	261	}
b7643757 SP	262
efc1a3b1	263	#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
16d69265 AM	264	void arch_pick_mmap_layout(struct mm_struct *mm)
	265	{
	266	mm->mmap_base = TASK_UNMAPPED_BASE;
	267	mm->get_unmapped_area = arch_get_unmapped_area;
16d69265 AM	268	}
16d69265 AM	269	#endif
912985dc	270
45888a0c XG	271	/*
	272	* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
	273	* back to the regular GUP.
25985edc	274	* If the architecture not support this function, simply return with no
45888a0c XG	275	* page pinned
45888a0c XG	276	*/
3b32123d	277	int __weak __get_user_pages_fast(unsigned long start,
45888a0c XG	278	int nr_pages, int write, struct page **pages)
	279	{
	280	return 0;
	281	}
	282	EXPORT_SYMBOL_GPL(__get_user_pages_fast);
	283
9de100d0 AG	284	/**
	285	* get_user_pages_fast() - pin user pages in memory
	286	* @start: starting user address
	287	* @nr_pages: number of pages from start to pin
	288	* @write: whether pages will be written to
	289	* @pages: array that receives pointers to the pages pinned.
	290	* Should be at least nr_pages long.
	291	*
9de100d0 AG	292	* Returns number of pages pinned. This may be fewer than the number
	293	* requested. If nr_pages is 0 or negative, returns 0. If no pages
	294	* were pinned, returns -errno.
d2bf6be8 NP	295	*
	296	* get_user_pages_fast provides equivalent functionality to get_user_pages,
	297	* operating on current and current->mm, with force=0 and vma=NULL. However
	298	* unlike get_user_pages, it must be called without mmap_sem held.
	299	*
	300	* get_user_pages_fast may take mmap_sem and page table locks, so no
	301	* assumptions can be made about lack of locking. get_user_pages_fast is to be
	302	* implemented in a way that is advantageous (vs get_user_pages()) when the
	303	* user memory area is already faulted in and present in ptes. However if the
	304	* pages have to be faulted in, it may turn out to be slightly slower so
	305	* callers need to carefully consider what to use. On many architectures,
	306	* get_user_pages_fast simply falls back to get_user_pages.
9de100d0	307	*/
3b32123d	308	int __weak get_user_pages_fast(unsigned long start,
912985dc RR	309	int nr_pages, int write, struct page **pages)
	310	{
	311	struct mm_struct *mm = current->mm;
a7b78075 AA	312	return get_user_pages_unlocked(current, mm, start, nr_pages,
a7b78075 AA	313	write, 0, pages);
912985dc RR	314	}
912985dc RR	315	EXPORT_SYMBOL_GPL(get_user_pages_fast);
ca2b84cb	316
eb36c587 AV	317	unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
	318	unsigned long len, unsigned long prot,
	319	unsigned long flag, unsigned long pgoff)
	320	{
	321	unsigned long ret;
	322	struct mm_struct *mm = current->mm;
41badc15	323	unsigned long populate;
eb36c587 AV	324
	325	ret = security_mmap_file(file, prot, flag);
	326	if (!ret) {
	327	down_write(&mm->mmap_sem);
bebeb3d6 ML	328	ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
bebeb3d6 ML	329	&populate);
eb36c587	330	up_write(&mm->mmap_sem);
41badc15 ML	331	if (populate)
41badc15 ML	332	mm_populate(ret, populate);
eb36c587 AV	333	}
	334	return ret;
	335	}
	336
	337	unsigned long vm_mmap(struct file *file, unsigned long addr,
	338	unsigned long len, unsigned long prot,
	339	unsigned long flag, unsigned long offset)
	340	{
	341	if (unlikely(offset + PAGE_ALIGN(len) < offset))
	342	return -EINVAL;
ea53cde0	343	if (unlikely(offset_in_page(offset)))
eb36c587 AV	344	return -EINVAL;
	345
	346	return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
	347	}
	348	EXPORT_SYMBOL(vm_mmap);
	349
39f1f78d AV	350	void kvfree(const void *addr)
	351	{
	352	if (is_vmalloc_addr(addr))
	353	vfree(addr);
	354	else
	355	kfree(addr);
	356	}
	357	EXPORT_SYMBOL(kvfree);
	358
e39155ea KS	359	static inline void __page_rmapping(struct page page)
	360	{
	361	unsigned long mapping;
	362
	363	mapping = (unsigned long)page->mapping;
	364	mapping &= ~PAGE_MAPPING_FLAGS;
	365
	366	return (void *)mapping;
	367	}
	368
	369	/* Neutral page->mapping pointer to address_space or anon_vma or other */
	370	void page_rmapping(struct page page)
	371	{
	372	page = compound_head(page);
	373	return __page_rmapping(page);
	374	}
	375
	376	struct anon_vma page_anon_vma(struct page page)
	377	{
	378	unsigned long mapping;
	379
	380	page = compound_head(page);
	381	mapping = (unsigned long)page->mapping;
	382	if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
	383	return NULL;
	384	return __page_rmapping(page);
	385	}
	386
9800339b SL	387	struct address_space page_mapping(struct page page)
9800339b SL	388	{
1c290f64 KS	389	struct address_space *mapping;
	390
	391	page = compound_head(page);
9800339b	392
03e5ac2f MP	393	/* This happens if someone calls flush_dcache_page on slab page */
	394	if (unlikely(PageSlab(page)))
	395	return NULL;
	396
33806f06 SL	397	if (unlikely(PageSwapCache(page))) {
	398	swp_entry_t entry;
	399
	400	entry.val = page_private(page);
e39155ea KS	401	return swap_address_space(entry);
	402	}
	403
1c290f64 KS	404	mapping = page->mapping;
1c290f64 KS	405	if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
e39155ea	406	return NULL;
1c290f64	407	return mapping;
9800339b SL	408	}
9800339b SL	409
b20ce5e0 KS	410	/* Slow path of page_mapcount() for compound pages */
	411	int __page_mapcount(struct page *page)
	412	{
	413	int ret;
	414
	415	ret = atomic_read(&page->_mapcount) + 1;
	416	page = compound_head(page);
	417	ret += atomic_read(compound_mapcount_ptr(page)) + 1;
	418	if (PageDoubleMap(page))
	419	ret--;
	420	return ret;
	421	}
	422	EXPORT_SYMBOL_GPL(__page_mapcount);
	423
49f0ce5f JM	424	int overcommit_ratio_handler(struct ctl_table *table, int write,
	425	void __user buffer, size_t lenp,
	426	loff_t *ppos)
	427	{
	428	int ret;
	429
	430	ret = proc_dointvec(table, write, buffer, lenp, ppos);
	431	if (ret == 0 && write)
	432	sysctl_overcommit_kbytes = 0;
	433	return ret;
	434	}
	435
	436	int overcommit_kbytes_handler(struct ctl_table *table, int write,
	437	void __user buffer, size_t lenp,
	438	loff_t *ppos)
	439	{
	440	int ret;
	441
	442	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
	443	if (ret == 0 && write)
	444	sysctl_overcommit_ratio = 0;
	445	return ret;
	446	}
	447
00619bcc JM	448	/*
	449	* Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
	450	*/
	451	unsigned long vm_commit_limit(void)
	452	{
49f0ce5f JM	453	unsigned long allowed;
	454
	455	if (sysctl_overcommit_kbytes)
	456	allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
	457	else
	458	allowed = ((totalram_pages - hugetlb_total_pages())
	459	* sysctl_overcommit_ratio / 100);
	460	allowed += total_swap_pages;
	461
	462	return allowed;
00619bcc JM	463	}
00619bcc JM	464
a9090253 WR	465	/**
	466	* get_cmdline() - copy the cmdline value to a buffer.
	467	* @task: the task whose cmdline value to copy.
	468	* @buffer: the buffer to copy to.
	469	* @buflen: the length of the buffer. Larger cmdline values are truncated
	470	* to this length.
	471	* Returns the size of the cmdline field copied. Note that the copy does
	472	* not guarantee an ending NULL byte.
	473	*/
	474	int get_cmdline(struct task_struct task, char buffer, int buflen)
	475	{
	476	int res = 0;
	477	unsigned int len;
	478	struct mm_struct *mm = get_task_mm(task);
	479	if (!mm)
	480	goto out;
	481	if (!mm->arg_end)
	482	goto out_mm; /* Shh! No looking before we're done */
	483
	484	len = mm->arg_end - mm->arg_start;
	485
	486	if (len > buflen)
	487	len = buflen;
	488
	489	res = access_process_vm(task, mm->arg_start, buffer, len, 0);
	490
	491	/*
	492	* If the nul at the end of args has been overwritten, then
	493	* assume application is using setproctitle(3).
	494	*/
	495	if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
	496	len = strnlen(buffer, res);
	497	if (len < res) {
	498	res = len;
	499	} else {
	500	len = mm->env_end - mm->env_start;
	501	if (len > buflen - res)
	502	len = buflen - res;
	503	res += access_process_vm(task, mm->env_start,
	504	buffer+res, len, 0);
	505	res = strnlen(buffer, res);
	506	}
	507	}
	508	out_mm:
	509	mmput(mm);
	510	out:
	511	return res;
	512	}