/* *	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.	 */	page = find_get_page(mapping, pgoff);#ifdef CONFIG_SWAP	/* shmem/tmpfs may return swap: account for swapcache page too. */	if (radix_tree_exceptional_entry(page)) {		swp_entry_t swap = radix_to_swp_entry(page);		page = find_get_page(&swapper_space, swap.val);	}#endif	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_trans_huge(*pmd)) {			if (mincore_huge_pmd(vma, pmd, addr, next, vec)) {				vec += (next - addr) >> PAGE_SHIFT;				continue;			}			/* fall through */		}		if (pmd_none_or_trans_huge_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;}