4 * Copyright (C) 1994-1999 Linus Torvalds
8 * The mincore() system call.
10 #include <linux/slab.h>
11 #include <linux/pagemap.h>
13 #include <linux/mman.h>
15 #include <asm/uaccess.h>
16 #include <asm/pgtable.h>
17 #include <asm/pgalloc.h>
20 * Later we can get more picky about what "in core" means precisely.
21 * For now, simply check to see if the page is in the page cache,
22 * and is up to date; i.e. that no page-in operation would be required
23 * at this time if an application were to map and access this page.
25 static unsigned char mincore_page(struct vm_area_struct * vma,
28 unsigned char present = 0;
29 struct address_space * as = vma->vm_file->f_mapping;
32 page = find_get_page(as, pgoff);
34 present = PageUptodate(page);
35 page_cache_release(page);
41 static long mincore_vma(struct vm_area_struct * vma,
42 unsigned long start, unsigned long end, unsigned char __user * vec)
44 long error, i, remaining;
51 start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
52 if (end > vma->vm_end)
54 end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
57 tmp = (unsigned char *) __get_free_page(GFP_KERNEL);
61 /* (end - start) is # of pages, and also # of bytes in "vec */
62 remaining = (end - start),
65 for (i = 0; remaining > 0; remaining -= PAGE_SIZE, i++) {
67 long thispiece = (remaining < PAGE_SIZE) ?
68 remaining : PAGE_SIZE;
71 tmp[j++] = mincore_page(vma, start++);
73 if (copy_to_user(vec + PAGE_SIZE * i, tmp, thispiece)) {
79 free_page((unsigned long) tmp);
84 * The mincore(2) system call.
86 * mincore() returns the memory residency status of the pages in the
87 * current process's address space specified by [addr, addr + len).
88 * The status is returned in a vector of bytes. The least significant
89 * bit of each byte is 1 if the referenced page is in memory, otherwise
92 * Because the status of a page can change after mincore() checks it
93 * but before it returns to the application, the returned vector may
94 * contain stale information. Only locked pages are guaranteed to
99 * -EFAULT - vec points to an illegal address
100 * -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE,
101 * or len has a nonpositive value
102 * -ENOMEM - Addresses in the range [addr, addr + len] are
103 * invalid for the address space of this process, or
104 * specify one or more pages which are not currently
106 * -EAGAIN - A kernel resource was temporarily unavailable.
108 asmlinkage long sys_mincore(unsigned long start, size_t len,
109 unsigned char __user * vec)
113 struct vm_area_struct * vma;
114 int unmapped_error = 0;
115 long error = -EINVAL;
117 down_read(¤t->mm->mmap_sem);
119 if (start & ~PAGE_CACHE_MASK)
121 len = (len + ~PAGE_CACHE_MASK) & PAGE_CACHE_MASK;
127 if (!access_ok(VERIFY_WRITE, vec, len >> PAGE_SHIFT))
135 * If the interval [start,end) covers some unmapped address
136 * ranges, just ignore them, but return -ENOMEM at the end.
138 vma = find_vma(current->mm, start);
140 /* Still start < end. */
145 /* Here start < vma->vm_end. */
146 if (start < vma->vm_start) {
147 unmapped_error = -ENOMEM;
148 start = vma->vm_start;
151 /* Here vma->vm_start <= start < vma->vm_end. */
152 if (end <= vma->vm_end) {
154 error = mincore_vma(vma, start, end,
159 error = unmapped_error;
163 /* Here vma->vm_start <= start < vma->vm_end < end. */
164 error = mincore_vma(vma, start, vma->vm_end, &vec[index]);
167 index += (vma->vm_end - start) >> PAGE_CACHE_SHIFT;
173 up_read(¤t->mm->mmap_sem);