[linux.git] / mm / mincore.c

/*
 *	linux/mm/mincore.c
 *
 * Copyright (C) 1994-2006  Linus Torvalds
 */

/*
 * The mincore() system call.
 */
#include <linux/pagemap.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/syscalls.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/hugetlb.h>

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

static void mincore_hugetlb_page_range(struct vm_area_struct *vma,
				unsigned long addr, unsigned long end,
				unsigned char *vec)
{
#ifdef CONFIG_HUGETLB_PAGE
	struct hstate *h;

	h = hstate_vma(vma);
	while (1) {
		unsigned char present;
		pte_t *ptep;
		/*
		 * Huge pages are always in RAM for now, but
		 * theoretically it needs to be checked.
		 */
		ptep = huge_pte_offset(current->mm,
				       addr & huge_page_mask(h));
		present = ptep && !huge_pte_none(huge_ptep_get(ptep));
		while (1) {
			*vec = present;
			vec++;
			addr += PAGE_SIZE;
			if (addr == end)
				return;
			/* check hugepage border */
			if (!(addr & ~huge_page_mask(h)))
				break;
		}
	}
#else
	BUG();
#endif
}

/*
 * Later we can get more picky about what "in core" means precisely.
 * For now, simply check to see if the page is in the page cache,
 * and is up to date; i.e. that no page-in operation would be required
 * at this time if an application were to map and access this page.
 */
static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
{
	unsigned char present = 0;
	struct page *page;

	/*
	 * When tmpfs swaps out a page from a file, any process mapping that
	 * file will not get a swp_entry_t in its pte, but rather it is like
	 * any other file mapping (ie. marked !present and faulted in with
	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
	 *
	 * However when tmpfs moves the page from pagecache and into swapcache,
	 * it is still in core, but the find_get_page below won't find it.
	 * No big deal, but make a note of it.
	 */
	page = find_get_page(mapping, pgoff);
	if (page) {
		present = PageUptodate(page);
		page_cache_release(page);
	}

	return present;
}

static void mincore_unmapped_range(struct vm_area_struct *vma,
				unsigned long addr, unsigned long end,
				unsigned char *vec)
{
	unsigned long nr = (end - addr) >> PAGE_SHIFT;
	int i;

	if (vma->vm_file) {
		pgoff_t pgoff;

		pgoff = linear_page_index(vma, addr);
		for (i = 0; i < nr; i++, pgoff++)
			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
	} else {
		for (i = 0; i < nr; i++)
			vec[i] = 0;
	}
}

static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
			unsigned long addr, unsigned long end,
			unsigned char *vec)
{
	unsigned long next;
	spinlock_t *ptl;
	pte_t *ptep;

	ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
	do {
		pte_t pte = *ptep;
		pgoff_t pgoff;

		next = addr + PAGE_SIZE;
		if (pte_none(pte))
			mincore_unmapped_range(vma, addr, next, vec);
		else if (pte_present(pte))
			*vec = 1;
		else if (pte_file(pte)) {
			pgoff = pte_to_pgoff(pte);
			*vec = mincore_page(vma->vm_file->f_mapping, pgoff);
		} else { /* pte is a swap entry */
			swp_entry_t entry = pte_to_swp_entry(pte);

			if (is_migration_entry(entry)) {
				/* migration entries are always uptodate */
				*vec = 1;
			} else {
#ifdef CONFIG_SWAP
				pgoff = entry.val;
				*vec = mincore_page(&swapper_space, pgoff);
#else
				WARN_ON(1);
				*vec = 1;
#endif
			}
		}
		vec++;
	} while (ptep++, addr = next, addr != end);
	pte_unmap_unlock(ptep - 1, ptl);
}

static void mincore_pmd_range(struct vm_area_struct *vma, pud_t *pud,
			unsigned long addr, unsigned long end,
			unsigned char *vec)
{
	unsigned long next;
	pmd_t *pmd;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			mincore_unmapped_range(vma, addr, next, vec);
		else
			mincore_pte_range(vma, pmd, addr, next, vec);
		vec += (next - addr) >> PAGE_SHIFT;
	} while (pmd++, addr = next, addr != end);
}

static void mincore_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
			unsigned long addr, unsigned long end,
			unsigned char *vec)
{
	unsigned long next;
	pud_t *pud;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			mincore_unmapped_range(vma, addr, next, vec);
		else
			mincore_pmd_range(vma, pud, addr, next, vec);
		vec += (next - addr) >> PAGE_SHIFT;
	} while (pud++, addr = next, addr != end);
}

static void mincore_page_range(struct vm_area_struct *vma,
			unsigned long addr, unsigned long end,
			unsigned char *vec)
{
	unsigned long next;
	pgd_t *pgd;

	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			mincore_unmapped_range(vma, addr, next, vec);
		else
			mincore_pud_range(vma, pgd, addr, next, vec);
		vec += (next - addr) >> PAGE_SHIFT;
	} while (pgd++, addr = next, addr != end);
}

/*
 * Do a chunk of "sys_mincore()". We've already checked
 * all the arguments, we hold the mmap semaphore: we should
 * just return the amount of info we're asked for.
 */
static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
{
	struct vm_area_struct *vma;
	unsigned long end;

	vma = find_vma(current->mm, addr);
	if (!vma || addr < vma->vm_start)
		return -ENOMEM;

	end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));

	if (is_vm_hugetlb_page(vma)) {
		mincore_hugetlb_page_range(vma, addr, end, vec);
		return (end - addr) >> PAGE_SHIFT;
	}

	end = pmd_addr_end(addr, end);

	if (is_vm_hugetlb_page(vma))
		mincore_hugetlb_page_range(vma, addr, end, vec);
	else
		mincore_page_range(vma, addr, end, vec);

	return (end - addr) >> PAGE_SHIFT;
}

/*
 * The mincore(2) system call.
 *
 * mincore() returns the memory residency status of the pages in the
 * current process's address space specified by [addr, addr + len).
 * The status is returned in a vector of bytes.  The least significant
 * bit of each byte is 1 if the referenced page is in memory, otherwise
 * it is zero.
 *
 * Because the status of a page can change after mincore() checks it
 * but before it returns to the application, the returned vector may
 * contain stale information.  Only locked pages are guaranteed to
 * remain in memory.
 *
 * return values:
 *  zero    - success
 *  -EFAULT - vec points to an illegal address
 *  -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE
 *  -ENOMEM - Addresses in the range [addr, addr + len] are
 *		invalid for the address space of this process, or
 *		specify one or more pages which are not currently
 *		mapped
 *  -EAGAIN - A kernel resource was temporarily unavailable.
 */
SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
		unsigned char __user *, vec)
{
	long retval;
	unsigned long pages;
	unsigned char *tmp;

	/* Check the start address: needs to be page-aligned.. */
 	if (start & ~PAGE_CACHE_MASK)
		return -EINVAL;

	/* ..and we need to be passed a valid user-space range */
	if (!access_ok(VERIFY_READ, (void __user *) start, len))
		return -ENOMEM;

	/* This also avoids any overflows on PAGE_CACHE_ALIGN */
	pages = len >> PAGE_SHIFT;
	pages += (len & ~PAGE_MASK) != 0;

	if (!access_ok(VERIFY_WRITE, vec, pages))
		return -EFAULT;

	tmp = (void *) __get_free_page(GFP_USER);
	if (!tmp)
		return -EAGAIN;

	retval = 0;
	while (pages) {
		/*
		 * Do at most PAGE_SIZE entries per iteration, due to
		 * the temporary buffer size.
		 */
		down_read(&current->mm->mmap_sem);
		retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
		up_read(&current->mm->mmap_sem);

		if (retval <= 0)
			break;
		if (copy_to_user(vec, tmp, retval)) {
			retval = -EFAULT;
			break;
		}
		pages -= retval;
		vec += retval;
		start += retval << PAGE_SHIFT;
		retval = 0;
	}
	free_page((unsigned long) tmp);
	return retval;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/mm/mincore.c
	3	*
2f77d107	4	* Copyright (C) 1994-2006 Linus Torvalds
1da177e4 LT	5	*/
	6
	7	/*
	8	* The mincore() system call.
	9	*/
1da177e4	10	#include <linux/pagemap.h>
5a0e3ad6	11	#include <linux/gfp.h>
1da177e4 LT	12	#include <linux/mm.h>
	13	#include <linux/mman.h>
	14	#include <linux/syscalls.h>
42da9cbd NP	15	#include <linux/swap.h>
42da9cbd NP	16	#include <linux/swapops.h>
4f16fc10	17	#include <linux/hugetlb.h>
1da177e4 LT	18
	19	#include <asm/uaccess.h>
	20	#include <asm/pgtable.h>
	21
f4884010	22	static void mincore_hugetlb_page_range(struct vm_area_struct *vma,
25ef0e50	23	unsigned long addr, unsigned long end,
f4884010 JW	24	unsigned char *vec)
	25	{
	26	#ifdef CONFIG_HUGETLB_PAGE
	27	struct hstate *h;
f4884010	28
f4884010 JW	29	h = hstate_vma(vma);
	30	while (1) {
	31	unsigned char present;
	32	pte_t *ptep;
	33	/*
	34	* Huge pages are always in RAM for now, but
	35	* theoretically it needs to be checked.
	36	*/
	37	ptep = huge_pte_offset(current->mm,
	38	addr & huge_page_mask(h));
	39	present = ptep && !huge_pte_none(huge_ptep_get(ptep));
	40	while (1) {
25ef0e50 JW	41	*vec = present;
25ef0e50 JW	42	vec++;
f4884010	43	addr += PAGE_SIZE;
25ef0e50	44	if (addr == end)
f4884010 JW	45	return;
	46	/* check hugepage border */
	47	if (!(addr & ~huge_page_mask(h)))
	48	break;
	49	}
	50	}
	51	#else
	52	BUG();
	53	#endif
	54	}
	55
1da177e4 LT	56	/*
	57	* Later we can get more picky about what "in core" means precisely.
	58	* For now, simply check to see if the page is in the page cache,
	59	* and is up to date; i.e. that no page-in operation would be required
	60	* at this time if an application were to map and access this page.
	61	*/
42da9cbd	62	static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
1da177e4 LT	63	{
1da177e4 LT	64	unsigned char present = 0;
42da9cbd	65	struct page *page;
1da177e4	66
42da9cbd NP	67	/*
	68	* When tmpfs swaps out a page from a file, any process mapping that
	69	* file will not get a swp_entry_t in its pte, but rather it is like
	70	* any other file mapping (ie. marked !present and faulted in with
3c18ddd1	71	* tmpfs's .fault). So swapped out tmpfs mappings are tested here.
42da9cbd NP	72	*
	73	* However when tmpfs moves the page from pagecache and into swapcache,
	74	* it is still in core, but the find_get_page below won't find it.
	75	* No big deal, but make a note of it.
	76	*/
	77	page = find_get_page(mapping, pgoff);
1da177e4 LT	78	if (page) {
	79	present = PageUptodate(page);
	80	page_cache_release(page);
	81	}
	82
	83	return present;
	84	}
	85
f4884010	86	static void mincore_unmapped_range(struct vm_area_struct *vma,
25ef0e50	87	unsigned long addr, unsigned long end,
f4884010 JW	88	unsigned char *vec)
f4884010 JW	89	{
25ef0e50	90	unsigned long nr = (end - addr) >> PAGE_SHIFT;
f4884010 JW	91	int i;
	92
	93	if (vma->vm_file) {
	94	pgoff_t pgoff;
	95
	96	pgoff = linear_page_index(vma, addr);
	97	for (i = 0; i < nr; i++, pgoff++)
	98	vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
	99	} else {
	100	for (i = 0; i < nr; i++)
	101	vec[i] = 0;
	102	}
	103	}
	104
	105	static void mincore_pte_range(struct vm_area_struct vma, pmd_t pmd,
25ef0e50	106	unsigned long addr, unsigned long end,
f4884010 JW	107	unsigned char *vec)
f4884010 JW	108	{
25ef0e50	109	unsigned long next;
f4884010 JW	110	spinlock_t *ptl;
f4884010 JW	111	pte_t *ptep;
f4884010 JW	112
f4884010 JW	113	ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
25ef0e50	114	do {
f4884010 JW	115	pte_t pte = *ptep;
	116	pgoff_t pgoff;
	117
25ef0e50	118	next = addr + PAGE_SIZE;
f4884010	119	if (pte_none(pte))
25ef0e50	120	mincore_unmapped_range(vma, addr, next, vec);
f4884010	121	else if (pte_present(pte))
25ef0e50	122	*vec = 1;
f4884010 JW	123	else if (pte_file(pte)) {
f4884010 JW	124	pgoff = pte_to_pgoff(pte);
25ef0e50	125	*vec = mincore_page(vma->vm_file->f_mapping, pgoff);
f4884010 JW	126	} else { /* pte is a swap entry */
	127	swp_entry_t entry = pte_to_swp_entry(pte);
	128
	129	if (is_migration_entry(entry)) {
	130	/* migration entries are always uptodate */
25ef0e50	131	*vec = 1;
f4884010 JW	132	} else {
	133	#ifdef CONFIG_SWAP
	134	pgoff = entry.val;
25ef0e50	135	*vec = mincore_page(&swapper_space, pgoff);
f4884010 JW	136	#else
f4884010 JW	137	WARN_ON(1);
25ef0e50	138	*vec = 1;
f4884010 JW	139	#endif
	140	}
	141	}
25ef0e50 JW	142	vec++;
25ef0e50 JW	143	} while (ptep++, addr = next, addr != end);
f4884010 JW	144	pte_unmap_unlock(ptep - 1, ptl);
	145	}
	146
e48293fd JW	147	static void mincore_pmd_range(struct vm_area_struct vma, pud_t pud,
	148	unsigned long addr, unsigned long end,
	149	unsigned char *vec)
	150	{
	151	unsigned long next;
	152	pmd_t *pmd;
	153
	154	pmd = pmd_offset(pud, addr);
	155	do {
	156	next = pmd_addr_end(addr, end);
	157	if (pmd_none_or_clear_bad(pmd))
	158	mincore_unmapped_range(vma, addr, next, vec);
	159	else
	160	mincore_pte_range(vma, pmd, addr, next, vec);
	161	vec += (next - addr) >> PAGE_SHIFT;
	162	} while (pmd++, addr = next, addr != end);
	163	}
	164
	165	static void mincore_pud_range(struct vm_area_struct vma, pgd_t pgd,
	166	unsigned long addr, unsigned long end,
	167	unsigned char *vec)
	168	{
	169	unsigned long next;
	170	pud_t *pud;
	171
	172	pud = pud_offset(pgd, addr);
	173	do {
	174	next = pud_addr_end(addr, end);
	175	if (pud_none_or_clear_bad(pud))
	176	mincore_unmapped_range(vma, addr, next, vec);
	177	else
	178	mincore_pmd_range(vma, pud, addr, next, vec);
	179	vec += (next - addr) >> PAGE_SHIFT;
	180	} while (pud++, addr = next, addr != end);
	181	}
	182
	183	static void mincore_page_range(struct vm_area_struct *vma,
	184	unsigned long addr, unsigned long end,
	185	unsigned char *vec)
	186	{
	187	unsigned long next;
	188	pgd_t *pgd;
	189
	190	pgd = pgd_offset(vma->vm_mm, addr);
	191	do {
	192	next = pgd_addr_end(addr, end);
	193	if (pgd_none_or_clear_bad(pgd))
	194	mincore_unmapped_range(vma, addr, next, vec);
	195	else
	196	mincore_pud_range(vma, pgd, addr, next, vec);
	197	vec += (next - addr) >> PAGE_SHIFT;
	198	} while (pgd++, addr = next, addr != end);
	199	}
	200
2f77d107 LT	201	/*
	202	* Do a chunk of "sys_mincore()". We've already checked
	203	* all the arguments, we hold the mmap semaphore: we should
	204	* just return the amount of info we're asked for.
	205	*/
6a60f1b3	206	static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
1da177e4	207	{
6a60f1b3	208	struct vm_area_struct *vma;
25ef0e50	209	unsigned long end;
1da177e4	210
6a60f1b3	211	vma = find_vma(current->mm, addr);
4fb23e43 LT	212	if (!vma \|\| addr < vma->vm_start)
4fb23e43 LT	213	return -ENOMEM;
1da177e4	214
25ef0e50	215	end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
6a60f1b3	216
4f16fc10	217	if (is_vm_hugetlb_page(vma)) {
25ef0e50 JW	218	mincore_hugetlb_page_range(vma, addr, end, vec);
25ef0e50 JW	219	return (end - addr) >> PAGE_SHIFT;
4f16fc10	220	}
4f16fc10	221
25ef0e50	222	end = pmd_addr_end(addr, end);
1da177e4	223
e48293fd JW	224	if (is_vm_hugetlb_page(vma))
	225	mincore_hugetlb_page_range(vma, addr, end, vec);
	226	else
	227	mincore_page_range(vma, addr, end, vec);
42da9cbd	228
25ef0e50	229	return (end - addr) >> PAGE_SHIFT;
1da177e4 LT	230	}
	231
	232	/*
	233	* The mincore(2) system call.
	234	*
	235	* mincore() returns the memory residency status of the pages in the
	236	* current process's address space specified by [addr, addr + len).
	237	* The status is returned in a vector of bytes. The least significant
	238	* bit of each byte is 1 if the referenced page is in memory, otherwise
	239	* it is zero.
	240	*
	241	* Because the status of a page can change after mincore() checks it
	242	* but before it returns to the application, the returned vector may
	243	* contain stale information. Only locked pages are guaranteed to
	244	* remain in memory.
	245	*
	246	* return values:
	247	* zero - success
	248	* -EFAULT - vec points to an illegal address
	249	* -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE
	250	* -ENOMEM - Addresses in the range [addr, addr + len] are
	251	* invalid for the address space of this process, or
	252	* specify one or more pages which are not currently
	253	* mapped
	254	* -EAGAIN - A kernel resource was temporarily unavailable.
	255	*/
3480b257 HC	256	SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
3480b257 HC	257	unsigned char __user *, vec)
1da177e4	258	{
2f77d107 LT	259	long retval;
	260	unsigned long pages;
	261	unsigned char *tmp;
1da177e4	262
2f77d107 LT	263	/* Check the start address: needs to be page-aligned.. */
	264	if (start & ~PAGE_CACHE_MASK)
	265	return -EINVAL;
1da177e4	266
2f77d107 LT	267	/* ..and we need to be passed a valid user-space range */
	268	if (!access_ok(VERIFY_READ, (void __user *) start, len))
	269	return -ENOMEM;
1da177e4	270
2f77d107 LT	271	/* This also avoids any overflows on PAGE_CACHE_ALIGN */
	272	pages = len >> PAGE_SHIFT;
	273	pages += (len & ~PAGE_MASK) != 0;
1da177e4	274
2f77d107 LT	275	if (!access_ok(VERIFY_WRITE, vec, pages))
2f77d107 LT	276	return -EFAULT;
1da177e4	277
2f77d107 LT	278	tmp = (void *) __get_free_page(GFP_USER);
2f77d107 LT	279	if (!tmp)
4fb23e43	280	return -EAGAIN;
2f77d107 LT	281
	282	retval = 0;
	283	while (pages) {
	284	/*
	285	* Do at most PAGE_SIZE entries per iteration, due to
	286	* the temporary buffer size.
	287	*/
	288	down_read(&current->mm->mmap_sem);
6a60f1b3	289	retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
2f77d107 LT	290	up_read(&current->mm->mmap_sem);
	291
	292	if (retval <= 0)
	293	break;
	294	if (copy_to_user(vec, tmp, retval)) {
	295	retval = -EFAULT;
	296	break;
1da177e4	297	}
2f77d107 LT	298	pages -= retval;
	299	vec += retval;
	300	start += retval << PAGE_SHIFT;
	301	retval = 0;
1da177e4	302	}
2f77d107 LT	303	free_page((unsigned long) tmp);
2f77d107 LT	304	return retval;
1da177e4	305	}