Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/mm/mincore.c |
| 3 | * |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 4 | * Copyright (C) 1994-2006 Linus Torvalds |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 5 | */ |
| 6 | |
| 7 | /* |
| 8 | * The mincore() system call. |
| 9 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 10 | #include <linux/pagemap.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 11 | #include <linux/gfp.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 12 | #include <linux/mm.h> |
| 13 | #include <linux/mman.h> |
| 14 | #include <linux/syscalls.h> |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 15 | #include <linux/swap.h> |
| 16 | #include <linux/swapops.h> |
Naoya Horiguchi | 4f16fc1 | 2009-12-14 17:59:58 -0800 | [diff] [blame] | 17 | #include <linux/hugetlb.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | |
| 19 | #include <asm/uaccess.h> |
| 20 | #include <asm/pgtable.h> |
| 21 | |
| 22 | /* |
| 23 | * Later we can get more picky about what "in core" means precisely. |
| 24 | * For now, simply check to see if the page is in the page cache, |
| 25 | * and is up to date; i.e. that no page-in operation would be required |
| 26 | * at this time if an application were to map and access this page. |
| 27 | */ |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 28 | static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | { |
| 30 | unsigned char present = 0; |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 31 | struct page *page; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 33 | /* |
| 34 | * When tmpfs swaps out a page from a file, any process mapping that |
| 35 | * file will not get a swp_entry_t in its pte, but rather it is like |
| 36 | * any other file mapping (ie. marked !present and faulted in with |
Nick Piggin | 3c18ddd | 2008-04-28 02:12:10 -0700 | [diff] [blame] | 37 | * tmpfs's .fault). So swapped out tmpfs mappings are tested here. |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 38 | * |
| 39 | * However when tmpfs moves the page from pagecache and into swapcache, |
| 40 | * it is still in core, but the find_get_page below won't find it. |
| 41 | * No big deal, but make a note of it. |
| 42 | */ |
| 43 | page = find_get_page(mapping, pgoff); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | if (page) { |
| 45 | present = PageUptodate(page); |
| 46 | page_cache_release(page); |
| 47 | } |
| 48 | |
| 49 | return present; |
| 50 | } |
| 51 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 52 | /* |
| 53 | * Do a chunk of "sys_mincore()". We've already checked |
| 54 | * all the arguments, we hold the mmap semaphore: we should |
| 55 | * just return the amount of info we're asked for. |
| 56 | */ |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 57 | static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | { |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 59 | pgd_t *pgd; |
| 60 | pud_t *pud; |
| 61 | pmd_t *pmd; |
| 62 | pte_t *ptep; |
| 63 | spinlock_t *ptl; |
| 64 | unsigned long nr; |
| 65 | int i; |
| 66 | pgoff_t pgoff; |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 67 | struct vm_area_struct *vma; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 69 | vma = find_vma(current->mm, addr); |
Linus Torvalds | 4fb23e4 | 2006-12-16 16:01:50 -0800 | [diff] [blame] | 70 | if (!vma || addr < vma->vm_start) |
| 71 | return -ENOMEM; |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 72 | |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 73 | nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT); |
| 74 | |
Naoya Horiguchi | 4f16fc1 | 2009-12-14 17:59:58 -0800 | [diff] [blame] | 75 | #ifdef CONFIG_HUGETLB_PAGE |
| 76 | if (is_vm_hugetlb_page(vma)) { |
| 77 | struct hstate *h; |
Naoya Horiguchi | 4f16fc1 | 2009-12-14 17:59:58 -0800 | [diff] [blame] | 78 | |
| 79 | i = 0; |
Naoya Horiguchi | 4f16fc1 | 2009-12-14 17:59:58 -0800 | [diff] [blame] | 80 | h = hstate_vma(vma); |
Naoya Horiguchi | 4f16fc1 | 2009-12-14 17:59:58 -0800 | [diff] [blame] | 81 | while (1) { |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 82 | unsigned char present; |
| 83 | /* |
| 84 | * Huge pages are always in RAM for now, but |
| 85 | * theoretically it needs to be checked. |
| 86 | */ |
Naoya Horiguchi | 4f16fc1 | 2009-12-14 17:59:58 -0800 | [diff] [blame] | 87 | ptep = huge_pte_offset(current->mm, |
| 88 | addr & huge_page_mask(h)); |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 89 | present = ptep && !huge_pte_none(huge_ptep_get(ptep)); |
Naoya Horiguchi | 4f16fc1 | 2009-12-14 17:59:58 -0800 | [diff] [blame] | 90 | while (1) { |
| 91 | vec[i++] = present; |
| 92 | addr += PAGE_SIZE; |
| 93 | /* reach buffer limit */ |
| 94 | if (i == nr) |
| 95 | return nr; |
| 96 | /* check hugepage border */ |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 97 | if (!(addr & ~huge_page_mask(h))) |
Naoya Horiguchi | 4f16fc1 | 2009-12-14 17:59:58 -0800 | [diff] [blame] | 98 | break; |
| 99 | } |
| 100 | } |
| 101 | return nr; |
| 102 | } |
| 103 | #endif |
| 104 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 105 | /* |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 106 | * Calculate how many pages there are left in the last level of the |
| 107 | * PTE array for our address. |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 108 | */ |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 109 | nr = min(nr, PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1))); |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 110 | |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 111 | pgd = pgd_offset(vma->vm_mm, addr); |
| 112 | if (pgd_none_or_clear_bad(pgd)) |
| 113 | goto none_mapped; |
| 114 | pud = pud_offset(pgd, addr); |
| 115 | if (pud_none_or_clear_bad(pud)) |
| 116 | goto none_mapped; |
| 117 | pmd = pmd_offset(pud, addr); |
| 118 | if (pmd_none_or_clear_bad(pmd)) |
| 119 | goto none_mapped; |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 120 | |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 121 | ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
| 122 | for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) { |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 123 | pte_t pte = *ptep; |
| 124 | |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 125 | if (pte_none(pte)) { |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 126 | if (vma->vm_file) { |
| 127 | pgoff = linear_page_index(vma, addr); |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 128 | vec[i] = mincore_page(vma->vm_file->f_mapping, |
| 129 | pgoff); |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 130 | } else |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 131 | vec[i] = 0; |
| 132 | } else if (pte_present(pte)) |
| 133 | vec[i] = 1; |
| 134 | else if (pte_file(pte)) { |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 135 | pgoff = pte_to_pgoff(pte); |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 136 | vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff); |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 137 | } else { /* pte is a swap entry */ |
| 138 | swp_entry_t entry = pte_to_swp_entry(pte); |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 139 | |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 140 | if (is_migration_entry(entry)) { |
| 141 | /* migration entries are always uptodate */ |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 142 | vec[i] = 1; |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 143 | } else { |
Nick Piggin | 30fcffe | 2007-02-14 12:35:02 +0100 | [diff] [blame] | 144 | #ifdef CONFIG_SWAP |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 145 | pgoff = entry.val; |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 146 | vec[i] = mincore_page(&swapper_space, pgoff); |
Nick Piggin | 30fcffe | 2007-02-14 12:35:02 +0100 | [diff] [blame] | 147 | #else |
| 148 | WARN_ON(1); |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 149 | vec[i] = 1; |
Nick Piggin | 30fcffe | 2007-02-14 12:35:02 +0100 | [diff] [blame] | 150 | #endif |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 151 | } |
| 152 | } |
| 153 | } |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 154 | pte_unmap_unlock(ptep - 1, ptl); |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 155 | |
| 156 | return nr; |
| 157 | |
| 158 | none_mapped: |
| 159 | if (vma->vm_file) { |
| 160 | pgoff = linear_page_index(vma, addr); |
| 161 | for (i = 0; i < nr; i++, pgoff++) |
| 162 | vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff); |
Nick Piggin | 4a76ef0 | 2007-02-14 12:36:32 +0100 | [diff] [blame] | 163 | } else { |
| 164 | for (i = 0; i < nr; i++) |
| 165 | vec[i] = 0; |
Nick Piggin | 42da9cb | 2007-02-12 00:51:39 -0800 | [diff] [blame] | 166 | } |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 167 | |
| 168 | return nr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 169 | } |
| 170 | |
| 171 | /* |
| 172 | * The mincore(2) system call. |
| 173 | * |
| 174 | * mincore() returns the memory residency status of the pages in the |
| 175 | * current process's address space specified by [addr, addr + len). |
| 176 | * The status is returned in a vector of bytes. The least significant |
| 177 | * bit of each byte is 1 if the referenced page is in memory, otherwise |
| 178 | * it is zero. |
| 179 | * |
| 180 | * Because the status of a page can change after mincore() checks it |
| 181 | * but before it returns to the application, the returned vector may |
| 182 | * contain stale information. Only locked pages are guaranteed to |
| 183 | * remain in memory. |
| 184 | * |
| 185 | * return values: |
| 186 | * zero - success |
| 187 | * -EFAULT - vec points to an illegal address |
| 188 | * -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE |
| 189 | * -ENOMEM - Addresses in the range [addr, addr + len] are |
| 190 | * invalid for the address space of this process, or |
| 191 | * specify one or more pages which are not currently |
| 192 | * mapped |
| 193 | * -EAGAIN - A kernel resource was temporarily unavailable. |
| 194 | */ |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 195 | SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len, |
| 196 | unsigned char __user *, vec) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | { |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 198 | long retval; |
| 199 | unsigned long pages; |
| 200 | unsigned char *tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 201 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 202 | /* Check the start address: needs to be page-aligned.. */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | if (start & ~PAGE_CACHE_MASK) |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 204 | return -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 205 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 206 | /* ..and we need to be passed a valid user-space range */ |
| 207 | if (!access_ok(VERIFY_READ, (void __user *) start, len)) |
| 208 | return -ENOMEM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 209 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 210 | /* This also avoids any overflows on PAGE_CACHE_ALIGN */ |
| 211 | pages = len >> PAGE_SHIFT; |
| 212 | pages += (len & ~PAGE_MASK) != 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 213 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 214 | if (!access_ok(VERIFY_WRITE, vec, pages)) |
| 215 | return -EFAULT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 216 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 217 | tmp = (void *) __get_free_page(GFP_USER); |
| 218 | if (!tmp) |
Linus Torvalds | 4fb23e4 | 2006-12-16 16:01:50 -0800 | [diff] [blame] | 219 | return -EAGAIN; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 220 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 221 | retval = 0; |
| 222 | while (pages) { |
| 223 | /* |
| 224 | * Do at most PAGE_SIZE entries per iteration, due to |
| 225 | * the temporary buffer size. |
| 226 | */ |
| 227 | down_read(¤t->mm->mmap_sem); |
Johannes Weiner | 6a60f1b | 2010-05-24 14:32:09 -0700 | [diff] [blame^] | 228 | retval = do_mincore(start, min(pages, PAGE_SIZE), tmp); |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 229 | up_read(¤t->mm->mmap_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 230 | |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 231 | if (retval <= 0) |
| 232 | break; |
| 233 | if (copy_to_user(vec, tmp, retval)) { |
| 234 | retval = -EFAULT; |
| 235 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 236 | } |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 237 | pages -= retval; |
| 238 | vec += retval; |
| 239 | start += retval << PAGE_SHIFT; |
| 240 | retval = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 241 | } |
Linus Torvalds | 2f77d10 | 2006-12-16 09:44:32 -0800 | [diff] [blame] | 242 | free_page((unsigned long) tmp); |
| 243 | return retval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 244 | } |