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>
19 * Later we can get more picky about what "in core" means precisely.
20 * For now, simply check to see if the page is in the page cache,
21 * and is up to date; i.e. that no page-in operation would be required
22 * at this time if an application were to map and access this page.
24 static unsigned char mincore_page(struct vm_area_struct * vma,
27 unsigned char present = 0;
28 struct address_space * as = vma->vm_file->f_mapping;
31 page = find_get_page(as, pgoff);
33 present = PageUptodate(page);
34 page_cache_release(page);
40 static long mincore_vma(struct vm_area_struct * vma,
41 unsigned long start, unsigned long end, unsigned char __user * vec)
43 long error, i, remaining;
50 start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
51 if (end > vma->vm_end)
53 end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
56 tmp = (unsigned char *) __get_free_page(GFP_KERNEL);
60 /* (end - start) is # of pages, and also # of bytes in "vec */
61 remaining = (end - start),
64 for (i = 0; remaining > 0; remaining -= PAGE_SIZE, i++) {
66 long thispiece = (remaining < PAGE_SIZE) ?
67 remaining : PAGE_SIZE;
70 tmp[j++] = mincore_page(vma, start++);
72 if (copy_to_user(vec + PAGE_SIZE * i, tmp, thispiece)) {
78 free_page((unsigned long) tmp);
83 * The mincore(2) system call.
85 * mincore() returns the memory residency status of the pages in the
86 * current process's address space specified by [addr, addr + len).
87 * The status is returned in a vector of bytes. The least significant
88 * bit of each byte is 1 if the referenced page is in memory, otherwise
91 * Because the status of a page can change after mincore() checks it
92 * but before it returns to the application, the returned vector may
93 * contain stale information. Only locked pages are guaranteed to
98 * -EFAULT - vec points to an illegal address
99 * -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE,
100 * or len has a nonpositive value
101 * -ENOMEM - Addresses in the range [addr, addr + len] are
102 * invalid for the address space of this process, or
103 * specify one or more pages which are not currently
105 * -EAGAIN - A kernel resource was temporarily unavailable.
107 asmlinkage long sys_mincore(unsigned long start, size_t len,
108 unsigned char __user * vec)
112 struct vm_area_struct * vma;
113 int unmapped_error = 0;
114 long error = -EINVAL;
116 down_read(¤t->mm->mmap_sem);
118 if (start & ~PAGE_CACHE_MASK)
120 len = (len + ~PAGE_CACHE_MASK) & PAGE_CACHE_MASK;
126 if (!access_ok(VERIFY_WRITE, vec, len >> PAGE_SHIFT))
134 * If the interval [start,end) covers some unmapped address
135 * ranges, just ignore them, but return -ENOMEM at the end.
137 vma = find_vma(current->mm, start);
139 /* Still start < end. */
144 /* Here start < vma->vm_end. */
145 if (start < vma->vm_start) {
146 unmapped_error = -ENOMEM;
147 start = vma->vm_start;
150 /* Here vma->vm_start <= start < vma->vm_end. */
151 if (end <= vma->vm_end) {
153 error = mincore_vma(vma, start, end,
158 error = unmapped_error;
162 /* Here vma->vm_start <= start < vma->vm_end < end. */
163 error = mincore_vma(vma, start, vma->vm_end, &vec[index]);
166 index += (vma->vm_end - start) >> PAGE_CACHE_SHIFT;
172 up_read(¤t->mm->mmap_sem);