1 /* 2 * linux/mm/nommu.c 3 * 4 * Replacement code for mm functions to support CPU's that don't 5 * have any form of memory management unit (thus no virtual memory). 6 * 7 * See Documentation/nommu-mmap.txt 8 * 9 * Copyright (c) 2004-2005 David Howells <dhowells@redhat.com> 10 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com> 11 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org> 12 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com> 13 */ 14 15 #include <linux/mm.h> 16 #include <linux/mman.h> 17 #include <linux/swap.h> 18 #include <linux/file.h> 19 #include <linux/highmem.h> 20 #include <linux/pagemap.h> 21 #include <linux/slab.h> 22 #include <linux/vmalloc.h> 23 #include <linux/ptrace.h> 24 #include <linux/blkdev.h> 25 #include <linux/backing-dev.h> 26 #include <linux/mount.h> 27 #include <linux/personality.h> 28 #include <linux/security.h> 29 #include <linux/syscalls.h> 30 31 #include <asm/uaccess.h> 32 #include <asm/tlb.h> 33 #include <asm/tlbflush.h> 34 35 void *high_memory; 36 struct page *mem_map; 37 unsigned long max_mapnr; 38 unsigned long num_physpages; 39 unsigned long askedalloc, realalloc; 40 atomic_t vm_committed_space = ATOMIC_INIT(0); 41 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 42 int sysctl_overcommit_ratio = 50; /* default is 50% */ 43 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 44 int heap_stack_gap = 0; 45 46 EXPORT_SYMBOL(mem_map); 47 EXPORT_SYMBOL(__vm_enough_memory); 48 EXPORT_SYMBOL(num_physpages); 49 50 /* list of shareable VMAs */ 51 struct rb_root nommu_vma_tree = RB_ROOT; 52 DECLARE_RWSEM(nommu_vma_sem); 53 54 struct vm_operations_struct generic_file_vm_ops = { 55 }; 56 57 EXPORT_SYMBOL(vfree); 58 EXPORT_SYMBOL(vmalloc_to_page); 59 EXPORT_SYMBOL(vmalloc_32); 60 EXPORT_SYMBOL(vmap); 61 EXPORT_SYMBOL(vunmap); 62 63 /* 64 * Handle all mappings that got truncated by a "truncate()" 65 * system call. 66 * 67 * NOTE! We have to be ready to update the memory sharing 68 * between the file and the memory map for a potential last 69 * incomplete page. Ugly, but necessary. 70 */ 71 int vmtruncate(struct inode *inode, loff_t offset) 72 { 73 struct address_space *mapping = inode->i_mapping; 74 unsigned long limit; 75 76 if (inode->i_size < offset) 77 goto do_expand; 78 i_size_write(inode, offset); 79 80 truncate_inode_pages(mapping, offset); 81 goto out_truncate; 82 83 do_expand: 84 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 85 if (limit != RLIM_INFINITY && offset > limit) 86 goto out_sig; 87 if (offset > inode->i_sb->s_maxbytes) 88 goto out; 89 i_size_write(inode, offset); 90 91 out_truncate: 92 if (inode->i_op && inode->i_op->truncate) 93 inode->i_op->truncate(inode); 94 return 0; 95 out_sig: 96 send_sig(SIGXFSZ, current, 0); 97 out: 98 return -EFBIG; 99 } 100 101 EXPORT_SYMBOL(vmtruncate); 102 103 /* 104 * Return the total memory allocated for this pointer, not 105 * just what the caller asked for. 106 * 107 * Doesn't have to be accurate, i.e. may have races. 108 */ 109 unsigned int kobjsize(const void *objp) 110 { 111 struct page *page; 112 113 if (!objp || !((page = virt_to_page(objp)))) 114 return 0; 115 116 if (PageSlab(page)) 117 return ksize(objp); 118 119 BUG_ON(page->index < 0); 120 BUG_ON(page->index >= MAX_ORDER); 121 122 return (PAGE_SIZE << page->index); 123 } 124 125 /* 126 * get a list of pages in an address range belonging to the specified process 127 * and indicate the VMA that covers each page 128 * - this is potentially dodgy as we may end incrementing the page count of a 129 * slab page or a secondary page from a compound page 130 * - don't permit access to VMAs that don't support it, such as I/O mappings 131 */ 132 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 133 unsigned long start, int len, int write, int force, 134 struct page **pages, struct vm_area_struct **vmas) 135 { 136 struct vm_area_struct *vma; 137 unsigned long vm_flags; 138 int i; 139 140 /* calculate required read or write permissions. 141 * - if 'force' is set, we only require the "MAY" flags. 142 */ 143 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 144 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 145 146 for (i = 0; i < len; i++) { 147 vma = find_vma(mm, start); 148 if (!vma) 149 goto finish_or_fault; 150 151 /* protect what we can, including chardevs */ 152 if (vma->vm_flags & (VM_IO | VM_PFNMAP) || 153 !(vm_flags & vma->vm_flags)) 154 goto finish_or_fault; 155 156 if (pages) { 157 pages[i] = virt_to_page(start); 158 if (pages[i]) 159 page_cache_get(pages[i]); 160 } 161 if (vmas) 162 vmas[i] = vma; 163 start += PAGE_SIZE; 164 } 165 166 return i; 167 168 finish_or_fault: 169 return i ? : -EFAULT; 170 } 171 172 EXPORT_SYMBOL(get_user_pages); 173 174 DEFINE_RWLOCK(vmlist_lock); 175 struct vm_struct *vmlist; 176 177 void vfree(void *addr) 178 { 179 kfree(addr); 180 } 181 182 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) 183 { 184 /* 185 * kmalloc doesn't like __GFP_HIGHMEM for some reason 186 */ 187 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); 188 } 189 190 struct page * vmalloc_to_page(void *addr) 191 { 192 return virt_to_page(addr); 193 } 194 195 unsigned long vmalloc_to_pfn(void *addr) 196 { 197 return page_to_pfn(virt_to_page(addr)); 198 } 199 200 201 long vread(char *buf, char *addr, unsigned long count) 202 { 203 memcpy(buf, addr, count); 204 return count; 205 } 206 207 long vwrite(char *buf, char *addr, unsigned long count) 208 { 209 /* Don't allow overflow */ 210 if ((unsigned long) addr + count < count) 211 count = -(unsigned long) addr; 212 213 memcpy(addr, buf, count); 214 return(count); 215 } 216 217 /* 218 * vmalloc - allocate virtually continguos memory 219 * 220 * @size: allocation size 221 * 222 * Allocate enough pages to cover @size from the page level 223 * allocator and map them into continguos kernel virtual space. 224 * 225 * For tight control over page level allocator and protection flags 226 * use __vmalloc() instead. 227 */ 228 void *vmalloc(unsigned long size) 229 { 230 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); 231 } 232 EXPORT_SYMBOL(vmalloc); 233 234 void *vmalloc_node(unsigned long size, int node) 235 { 236 return vmalloc(size); 237 } 238 EXPORT_SYMBOL(vmalloc_node); 239 240 /* 241 * vmalloc_32 - allocate virtually continguos memory (32bit addressable) 242 * 243 * @size: allocation size 244 * 245 * Allocate enough 32bit PA addressable pages to cover @size from the 246 * page level allocator and map them into continguos kernel virtual space. 247 */ 248 void *vmalloc_32(unsigned long size) 249 { 250 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); 251 } 252 253 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 254 { 255 BUG(); 256 return NULL; 257 } 258 259 void vunmap(void *addr) 260 { 261 BUG(); 262 } 263 264 /* 265 * Implement a stub for vmalloc_sync_all() if the architecture chose not to 266 * have one. 267 */ 268 void __attribute__((weak)) vmalloc_sync_all(void) 269 { 270 } 271 272 /* 273 * sys_brk() for the most part doesn't need the global kernel 274 * lock, except when an application is doing something nasty 275 * like trying to un-brk an area that has already been mapped 276 * to a regular file. in this case, the unmapping will need 277 * to invoke file system routines that need the global lock. 278 */ 279 asmlinkage unsigned long sys_brk(unsigned long brk) 280 { 281 struct mm_struct *mm = current->mm; 282 283 if (brk < mm->start_brk || brk > mm->context.end_brk) 284 return mm->brk; 285 286 if (mm->brk == brk) 287 return mm->brk; 288 289 /* 290 * Always allow shrinking brk 291 */ 292 if (brk <= mm->brk) { 293 mm->brk = brk; 294 return brk; 295 } 296 297 /* 298 * Ok, looks good - let it rip. 299 */ 300 return mm->brk = brk; 301 } 302 303 #ifdef DEBUG 304 static void show_process_blocks(void) 305 { 306 struct vm_list_struct *vml; 307 308 printk("Process blocks %d:", current->pid); 309 310 for (vml = ¤t->mm->context.vmlist; vml; vml = vml->next) { 311 printk(" %p: %p", vml, vml->vma); 312 if (vml->vma) 313 printk(" (%d @%lx #%d)", 314 kobjsize((void *) vml->vma->vm_start), 315 vml->vma->vm_start, 316 atomic_read(&vml->vma->vm_usage)); 317 printk(vml->next ? " ->" : ".\n"); 318 } 319 } 320 #endif /* DEBUG */ 321 322 /* 323 * add a VMA into a process's mm_struct in the appropriate place in the list 324 * - should be called with mm->mmap_sem held writelocked 325 */ 326 static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml) 327 { 328 struct vm_list_struct **ppv; 329 330 for (ppv = ¤t->mm->context.vmlist; *ppv; ppv = &(*ppv)->next) 331 if ((*ppv)->vma->vm_start > vml->vma->vm_start) 332 break; 333 334 vml->next = *ppv; 335 *ppv = vml; 336 } 337 338 /* 339 * look up the first VMA in which addr resides, NULL if none 340 * - should be called with mm->mmap_sem at least held readlocked 341 */ 342 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 343 { 344 struct vm_list_struct *loop, *vml; 345 346 /* search the vm_start ordered list */ 347 vml = NULL; 348 for (loop = mm->context.vmlist; loop; loop = loop->next) { 349 if (loop->vma->vm_start > addr) 350 break; 351 vml = loop; 352 } 353 354 if (vml && vml->vma->vm_end > addr) 355 return vml->vma; 356 357 return NULL; 358 } 359 EXPORT_SYMBOL(find_vma); 360 361 /* 362 * find a VMA 363 * - we don't extend stack VMAs under NOMMU conditions 364 */ 365 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) 366 { 367 return find_vma(mm, addr); 368 } 369 370 /* 371 * look up the first VMA exactly that exactly matches addr 372 * - should be called with mm->mmap_sem at least held readlocked 373 */ 374 static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm, 375 unsigned long addr) 376 { 377 struct vm_list_struct *vml; 378 379 /* search the vm_start ordered list */ 380 for (vml = mm->context.vmlist; vml; vml = vml->next) { 381 if (vml->vma->vm_start == addr) 382 return vml->vma; 383 if (vml->vma->vm_start > addr) 384 break; 385 } 386 387 return NULL; 388 } 389 390 /* 391 * find a VMA in the global tree 392 */ 393 static inline struct vm_area_struct *find_nommu_vma(unsigned long start) 394 { 395 struct vm_area_struct *vma; 396 struct rb_node *n = nommu_vma_tree.rb_node; 397 398 while (n) { 399 vma = rb_entry(n, struct vm_area_struct, vm_rb); 400 401 if (start < vma->vm_start) 402 n = n->rb_left; 403 else if (start > vma->vm_start) 404 n = n->rb_right; 405 else 406 return vma; 407 } 408 409 return NULL; 410 } 411 412 /* 413 * add a VMA in the global tree 414 */ 415 static void add_nommu_vma(struct vm_area_struct *vma) 416 { 417 struct vm_area_struct *pvma; 418 struct address_space *mapping; 419 struct rb_node **p = &nommu_vma_tree.rb_node; 420 struct rb_node *parent = NULL; 421 422 /* add the VMA to the mapping */ 423 if (vma->vm_file) { 424 mapping = vma->vm_file->f_mapping; 425 426 flush_dcache_mmap_lock(mapping); 427 vma_prio_tree_insert(vma, &mapping->i_mmap); 428 flush_dcache_mmap_unlock(mapping); 429 } 430 431 /* add the VMA to the master list */ 432 while (*p) { 433 parent = *p; 434 pvma = rb_entry(parent, struct vm_area_struct, vm_rb); 435 436 if (vma->vm_start < pvma->vm_start) { 437 p = &(*p)->rb_left; 438 } 439 else if (vma->vm_start > pvma->vm_start) { 440 p = &(*p)->rb_right; 441 } 442 else { 443 /* mappings are at the same address - this can only 444 * happen for shared-mem chardevs and shared file 445 * mappings backed by ramfs/tmpfs */ 446 BUG_ON(!(pvma->vm_flags & VM_SHARED)); 447 448 if (vma < pvma) 449 p = &(*p)->rb_left; 450 else if (vma > pvma) 451 p = &(*p)->rb_right; 452 else 453 BUG(); 454 } 455 } 456 457 rb_link_node(&vma->vm_rb, parent, p); 458 rb_insert_color(&vma->vm_rb, &nommu_vma_tree); 459 } 460 461 /* 462 * delete a VMA from the global list 463 */ 464 static void delete_nommu_vma(struct vm_area_struct *vma) 465 { 466 struct address_space *mapping; 467 468 /* remove the VMA from the mapping */ 469 if (vma->vm_file) { 470 mapping = vma->vm_file->f_mapping; 471 472 flush_dcache_mmap_lock(mapping); 473 vma_prio_tree_remove(vma, &mapping->i_mmap); 474 flush_dcache_mmap_unlock(mapping); 475 } 476 477 /* remove from the master list */ 478 rb_erase(&vma->vm_rb, &nommu_vma_tree); 479 } 480 481 /* 482 * determine whether a mapping should be permitted and, if so, what sort of 483 * mapping we're capable of supporting 484 */ 485 static int validate_mmap_request(struct file *file, 486 unsigned long addr, 487 unsigned long len, 488 unsigned long prot, 489 unsigned long flags, 490 unsigned long pgoff, 491 unsigned long *_capabilities) 492 { 493 unsigned long capabilities; 494 unsigned long reqprot = prot; 495 int ret; 496 497 /* do the simple checks first */ 498 if (flags & MAP_FIXED || addr) { 499 printk(KERN_DEBUG 500 "%d: Can't do fixed-address/overlay mmap of RAM\n", 501 current->pid); 502 return -EINVAL; 503 } 504 505 if ((flags & MAP_TYPE) != MAP_PRIVATE && 506 (flags & MAP_TYPE) != MAP_SHARED) 507 return -EINVAL; 508 509 if (!len) 510 return -EINVAL; 511 512 /* Careful about overflows.. */ 513 len = PAGE_ALIGN(len); 514 if (!len || len > TASK_SIZE) 515 return -ENOMEM; 516 517 /* offset overflow? */ 518 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 519 return -EOVERFLOW; 520 521 if (file) { 522 /* validate file mapping requests */ 523 struct address_space *mapping; 524 525 /* files must support mmap */ 526 if (!file->f_op || !file->f_op->mmap) 527 return -ENODEV; 528 529 /* work out if what we've got could possibly be shared 530 * - we support chardevs that provide their own "memory" 531 * - we support files/blockdevs that are memory backed 532 */ 533 mapping = file->f_mapping; 534 if (!mapping) 535 mapping = file->f_path.dentry->d_inode->i_mapping; 536 537 capabilities = 0; 538 if (mapping && mapping->backing_dev_info) 539 capabilities = mapping->backing_dev_info->capabilities; 540 541 if (!capabilities) { 542 /* no explicit capabilities set, so assume some 543 * defaults */ 544 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) { 545 case S_IFREG: 546 case S_IFBLK: 547 capabilities = BDI_CAP_MAP_COPY; 548 break; 549 550 case S_IFCHR: 551 capabilities = 552 BDI_CAP_MAP_DIRECT | 553 BDI_CAP_READ_MAP | 554 BDI_CAP_WRITE_MAP; 555 break; 556 557 default: 558 return -EINVAL; 559 } 560 } 561 562 /* eliminate any capabilities that we can't support on this 563 * device */ 564 if (!file->f_op->get_unmapped_area) 565 capabilities &= ~BDI_CAP_MAP_DIRECT; 566 if (!file->f_op->read) 567 capabilities &= ~BDI_CAP_MAP_COPY; 568 569 if (flags & MAP_SHARED) { 570 /* do checks for writing, appending and locking */ 571 if ((prot & PROT_WRITE) && 572 !(file->f_mode & FMODE_WRITE)) 573 return -EACCES; 574 575 if (IS_APPEND(file->f_path.dentry->d_inode) && 576 (file->f_mode & FMODE_WRITE)) 577 return -EACCES; 578 579 if (locks_verify_locked(file->f_path.dentry->d_inode)) 580 return -EAGAIN; 581 582 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 583 return -ENODEV; 584 585 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || 586 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || 587 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) 588 ) { 589 printk("MAP_SHARED not completely supported on !MMU\n"); 590 return -EINVAL; 591 } 592 593 /* we mustn't privatise shared mappings */ 594 capabilities &= ~BDI_CAP_MAP_COPY; 595 } 596 else { 597 /* we're going to read the file into private memory we 598 * allocate */ 599 if (!(capabilities & BDI_CAP_MAP_COPY)) 600 return -ENODEV; 601 602 /* we don't permit a private writable mapping to be 603 * shared with the backing device */ 604 if (prot & PROT_WRITE) 605 capabilities &= ~BDI_CAP_MAP_DIRECT; 606 } 607 608 /* handle executable mappings and implied executable 609 * mappings */ 610 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 611 if (prot & PROT_EXEC) 612 return -EPERM; 613 } 614 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 615 /* handle implication of PROT_EXEC by PROT_READ */ 616 if (current->personality & READ_IMPLIES_EXEC) { 617 if (capabilities & BDI_CAP_EXEC_MAP) 618 prot |= PROT_EXEC; 619 } 620 } 621 else if ((prot & PROT_READ) && 622 (prot & PROT_EXEC) && 623 !(capabilities & BDI_CAP_EXEC_MAP) 624 ) { 625 /* backing file is not executable, try to copy */ 626 capabilities &= ~BDI_CAP_MAP_DIRECT; 627 } 628 } 629 else { 630 /* anonymous mappings are always memory backed and can be 631 * privately mapped 632 */ 633 capabilities = BDI_CAP_MAP_COPY; 634 635 /* handle PROT_EXEC implication by PROT_READ */ 636 if ((prot & PROT_READ) && 637 (current->personality & READ_IMPLIES_EXEC)) 638 prot |= PROT_EXEC; 639 } 640 641 /* allow the security API to have its say */ 642 ret = security_file_mmap(file, reqprot, prot, flags); 643 if (ret < 0) 644 return ret; 645 646 /* looks okay */ 647 *_capabilities = capabilities; 648 return 0; 649 } 650 651 /* 652 * we've determined that we can make the mapping, now translate what we 653 * now know into VMA flags 654 */ 655 static unsigned long determine_vm_flags(struct file *file, 656 unsigned long prot, 657 unsigned long flags, 658 unsigned long capabilities) 659 { 660 unsigned long vm_flags; 661 662 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); 663 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 664 /* vm_flags |= mm->def_flags; */ 665 666 if (!(capabilities & BDI_CAP_MAP_DIRECT)) { 667 /* attempt to share read-only copies of mapped file chunks */ 668 if (file && !(prot & PROT_WRITE)) 669 vm_flags |= VM_MAYSHARE; 670 } 671 else { 672 /* overlay a shareable mapping on the backing device or inode 673 * if possible - used for chardevs, ramfs/tmpfs/shmfs and 674 * romfs/cramfs */ 675 if (flags & MAP_SHARED) 676 vm_flags |= VM_MAYSHARE | VM_SHARED; 677 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0) 678 vm_flags |= VM_MAYSHARE; 679 } 680 681 /* refuse to let anyone share private mappings with this process if 682 * it's being traced - otherwise breakpoints set in it may interfere 683 * with another untraced process 684 */ 685 if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED)) 686 vm_flags &= ~VM_MAYSHARE; 687 688 return vm_flags; 689 } 690 691 /* 692 * set up a shared mapping on a file 693 */ 694 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len) 695 { 696 int ret; 697 698 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 699 if (ret != -ENOSYS) 700 return ret; 701 702 /* getting an ENOSYS error indicates that direct mmap isn't 703 * possible (as opposed to tried but failed) so we'll fall 704 * through to making a private copy of the data and mapping 705 * that if we can */ 706 return -ENODEV; 707 } 708 709 /* 710 * set up a private mapping or an anonymous shared mapping 711 */ 712 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len) 713 { 714 void *base; 715 int ret; 716 717 /* invoke the file's mapping function so that it can keep track of 718 * shared mappings on devices or memory 719 * - VM_MAYSHARE will be set if it may attempt to share 720 */ 721 if (vma->vm_file) { 722 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 723 if (ret != -ENOSYS) { 724 /* shouldn't return success if we're not sharing */ 725 BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE)); 726 return ret; /* success or a real error */ 727 } 728 729 /* getting an ENOSYS error indicates that direct mmap isn't 730 * possible (as opposed to tried but failed) so we'll try to 731 * make a private copy of the data and map that instead */ 732 } 733 734 /* allocate some memory to hold the mapping 735 * - note that this may not return a page-aligned address if the object 736 * we're allocating is smaller than a page 737 */ 738 base = kmalloc(len, GFP_KERNEL|__GFP_COMP); 739 if (!base) 740 goto enomem; 741 742 vma->vm_start = (unsigned long) base; 743 vma->vm_end = vma->vm_start + len; 744 vma->vm_flags |= VM_MAPPED_COPY; 745 746 #ifdef WARN_ON_SLACK 747 if (len + WARN_ON_SLACK <= kobjsize(result)) 748 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n", 749 len, current->pid, kobjsize(result) - len); 750 #endif 751 752 if (vma->vm_file) { 753 /* read the contents of a file into the copy */ 754 mm_segment_t old_fs; 755 loff_t fpos; 756 757 fpos = vma->vm_pgoff; 758 fpos <<= PAGE_SHIFT; 759 760 old_fs = get_fs(); 761 set_fs(KERNEL_DS); 762 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos); 763 set_fs(old_fs); 764 765 if (ret < 0) 766 goto error_free; 767 768 /* clear the last little bit */ 769 if (ret < len) 770 memset(base + ret, 0, len - ret); 771 772 } else { 773 /* if it's an anonymous mapping, then just clear it */ 774 memset(base, 0, len); 775 } 776 777 return 0; 778 779 error_free: 780 kfree(base); 781 vma->vm_start = 0; 782 return ret; 783 784 enomem: 785 printk("Allocation of length %lu from process %d failed\n", 786 len, current->pid); 787 show_free_areas(); 788 return -ENOMEM; 789 } 790 791 /* 792 * handle mapping creation for uClinux 793 */ 794 unsigned long do_mmap_pgoff(struct file *file, 795 unsigned long addr, 796 unsigned long len, 797 unsigned long prot, 798 unsigned long flags, 799 unsigned long pgoff) 800 { 801 struct vm_list_struct *vml = NULL; 802 struct vm_area_struct *vma = NULL; 803 struct rb_node *rb; 804 unsigned long capabilities, vm_flags; 805 void *result; 806 int ret; 807 808 /* decide whether we should attempt the mapping, and if so what sort of 809 * mapping */ 810 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 811 &capabilities); 812 if (ret < 0) 813 return ret; 814 815 /* we've determined that we can make the mapping, now translate what we 816 * now know into VMA flags */ 817 vm_flags = determine_vm_flags(file, prot, flags, capabilities); 818 819 /* we're going to need to record the mapping if it works */ 820 vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL); 821 if (!vml) 822 goto error_getting_vml; 823 824 down_write(&nommu_vma_sem); 825 826 /* if we want to share, we need to check for VMAs created by other 827 * mmap() calls that overlap with our proposed mapping 828 * - we can only share with an exact match on most regular files 829 * - shared mappings on character devices and memory backed files are 830 * permitted to overlap inexactly as far as we are concerned for in 831 * these cases, sharing is handled in the driver or filesystem rather 832 * than here 833 */ 834 if (vm_flags & VM_MAYSHARE) { 835 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 836 unsigned long vmpglen; 837 838 /* suppress VMA sharing for shared regions */ 839 if (vm_flags & VM_SHARED && 840 capabilities & BDI_CAP_MAP_DIRECT) 841 goto dont_share_VMAs; 842 843 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) { 844 vma = rb_entry(rb, struct vm_area_struct, vm_rb); 845 846 if (!(vma->vm_flags & VM_MAYSHARE)) 847 continue; 848 849 /* search for overlapping mappings on the same file */ 850 if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode) 851 continue; 852 853 if (vma->vm_pgoff >= pgoff + pglen) 854 continue; 855 856 vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1; 857 vmpglen >>= PAGE_SHIFT; 858 if (pgoff >= vma->vm_pgoff + vmpglen) 859 continue; 860 861 /* handle inexactly overlapping matches between mappings */ 862 if (vma->vm_pgoff != pgoff || vmpglen != pglen) { 863 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 864 goto sharing_violation; 865 continue; 866 } 867 868 /* we've found a VMA we can share */ 869 atomic_inc(&vma->vm_usage); 870 871 vml->vma = vma; 872 result = (void *) vma->vm_start; 873 goto shared; 874 } 875 876 dont_share_VMAs: 877 vma = NULL; 878 879 /* obtain the address at which to make a shared mapping 880 * - this is the hook for quasi-memory character devices to 881 * tell us the location of a shared mapping 882 */ 883 if (file && file->f_op->get_unmapped_area) { 884 addr = file->f_op->get_unmapped_area(file, addr, len, 885 pgoff, flags); 886 if (IS_ERR((void *) addr)) { 887 ret = addr; 888 if (ret != (unsigned long) -ENOSYS) 889 goto error; 890 891 /* the driver refused to tell us where to site 892 * the mapping so we'll have to attempt to copy 893 * it */ 894 ret = (unsigned long) -ENODEV; 895 if (!(capabilities & BDI_CAP_MAP_COPY)) 896 goto error; 897 898 capabilities &= ~BDI_CAP_MAP_DIRECT; 899 } 900 } 901 } 902 903 /* we're going to need a VMA struct as well */ 904 vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL); 905 if (!vma) 906 goto error_getting_vma; 907 908 INIT_LIST_HEAD(&vma->anon_vma_node); 909 atomic_set(&vma->vm_usage, 1); 910 if (file) 911 get_file(file); 912 vma->vm_file = file; 913 vma->vm_flags = vm_flags; 914 vma->vm_start = addr; 915 vma->vm_end = addr + len; 916 vma->vm_pgoff = pgoff; 917 918 vml->vma = vma; 919 920 /* set up the mapping */ 921 if (file && vma->vm_flags & VM_SHARED) 922 ret = do_mmap_shared_file(vma, len); 923 else 924 ret = do_mmap_private(vma, len); 925 if (ret < 0) 926 goto error; 927 928 /* okay... we have a mapping; now we have to register it */ 929 result = (void *) vma->vm_start; 930 931 if (vma->vm_flags & VM_MAPPED_COPY) { 932 realalloc += kobjsize(result); 933 askedalloc += len; 934 } 935 936 realalloc += kobjsize(vma); 937 askedalloc += sizeof(*vma); 938 939 current->mm->total_vm += len >> PAGE_SHIFT; 940 941 add_nommu_vma(vma); 942 943 shared: 944 realalloc += kobjsize(vml); 945 askedalloc += sizeof(*vml); 946 947 add_vma_to_mm(current->mm, vml); 948 949 up_write(&nommu_vma_sem); 950 951 if (prot & PROT_EXEC) 952 flush_icache_range((unsigned long) result, 953 (unsigned long) result + len); 954 955 #ifdef DEBUG 956 printk("do_mmap:\n"); 957 show_process_blocks(); 958 #endif 959 960 return (unsigned long) result; 961 962 error: 963 up_write(&nommu_vma_sem); 964 kfree(vml); 965 if (vma) { 966 if (vma->vm_file) 967 fput(vma->vm_file); 968 kfree(vma); 969 } 970 return ret; 971 972 sharing_violation: 973 up_write(&nommu_vma_sem); 974 printk("Attempt to share mismatched mappings\n"); 975 kfree(vml); 976 return -EINVAL; 977 978 error_getting_vma: 979 up_write(&nommu_vma_sem); 980 kfree(vml); 981 printk("Allocation of vma for %lu byte allocation from process %d failed\n", 982 len, current->pid); 983 show_free_areas(); 984 return -ENOMEM; 985 986 error_getting_vml: 987 printk("Allocation of vml for %lu byte allocation from process %d failed\n", 988 len, current->pid); 989 show_free_areas(); 990 return -ENOMEM; 991 } 992 993 /* 994 * handle mapping disposal for uClinux 995 */ 996 static void put_vma(struct vm_area_struct *vma) 997 { 998 if (vma) { 999 down_write(&nommu_vma_sem); 1000 1001 if (atomic_dec_and_test(&vma->vm_usage)) { 1002 delete_nommu_vma(vma); 1003 1004 if (vma->vm_ops && vma->vm_ops->close) 1005 vma->vm_ops->close(vma); 1006 1007 /* IO memory and memory shared directly out of the pagecache from 1008 * ramfs/tmpfs mustn't be released here */ 1009 if (vma->vm_flags & VM_MAPPED_COPY) { 1010 realalloc -= kobjsize((void *) vma->vm_start); 1011 askedalloc -= vma->vm_end - vma->vm_start; 1012 kfree((void *) vma->vm_start); 1013 } 1014 1015 realalloc -= kobjsize(vma); 1016 askedalloc -= sizeof(*vma); 1017 1018 if (vma->vm_file) 1019 fput(vma->vm_file); 1020 kfree(vma); 1021 } 1022 1023 up_write(&nommu_vma_sem); 1024 } 1025 } 1026 1027 /* 1028 * release a mapping 1029 * - under NOMMU conditions the parameters must match exactly to the mapping to 1030 * be removed 1031 */ 1032 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len) 1033 { 1034 struct vm_list_struct *vml, **parent; 1035 unsigned long end = addr + len; 1036 1037 #ifdef DEBUG 1038 printk("do_munmap:\n"); 1039 #endif 1040 1041 for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) { 1042 if ((*parent)->vma->vm_start > addr) 1043 break; 1044 if ((*parent)->vma->vm_start == addr && 1045 ((len == 0) || ((*parent)->vma->vm_end == end))) 1046 goto found; 1047 } 1048 1049 printk("munmap of non-mmaped memory by process %d (%s): %p\n", 1050 current->pid, current->comm, (void *) addr); 1051 return -EINVAL; 1052 1053 found: 1054 vml = *parent; 1055 1056 put_vma(vml->vma); 1057 1058 *parent = vml->next; 1059 realalloc -= kobjsize(vml); 1060 askedalloc -= sizeof(*vml); 1061 kfree(vml); 1062 1063 update_hiwater_vm(mm); 1064 mm->total_vm -= len >> PAGE_SHIFT; 1065 1066 #ifdef DEBUG 1067 show_process_blocks(); 1068 #endif 1069 1070 return 0; 1071 } 1072 1073 asmlinkage long sys_munmap(unsigned long addr, size_t len) 1074 { 1075 int ret; 1076 struct mm_struct *mm = current->mm; 1077 1078 down_write(&mm->mmap_sem); 1079 ret = do_munmap(mm, addr, len); 1080 up_write(&mm->mmap_sem); 1081 return ret; 1082 } 1083 1084 /* 1085 * Release all mappings 1086 */ 1087 void exit_mmap(struct mm_struct * mm) 1088 { 1089 struct vm_list_struct *tmp; 1090 1091 if (mm) { 1092 #ifdef DEBUG 1093 printk("Exit_mmap:\n"); 1094 #endif 1095 1096 mm->total_vm = 0; 1097 1098 while ((tmp = mm->context.vmlist)) { 1099 mm->context.vmlist = tmp->next; 1100 put_vma(tmp->vma); 1101 1102 realalloc -= kobjsize(tmp); 1103 askedalloc -= sizeof(*tmp); 1104 kfree(tmp); 1105 } 1106 1107 #ifdef DEBUG 1108 show_process_blocks(); 1109 #endif 1110 } 1111 } 1112 1113 unsigned long do_brk(unsigned long addr, unsigned long len) 1114 { 1115 return -ENOMEM; 1116 } 1117 1118 /* 1119 * expand (or shrink) an existing mapping, potentially moving it at the same 1120 * time (controlled by the MREMAP_MAYMOVE flag and available VM space) 1121 * 1122 * under NOMMU conditions, we only permit changing a mapping's size, and only 1123 * as long as it stays within the hole allocated by the kmalloc() call in 1124 * do_mmap_pgoff() and the block is not shareable 1125 * 1126 * MREMAP_FIXED is not supported under NOMMU conditions 1127 */ 1128 unsigned long do_mremap(unsigned long addr, 1129 unsigned long old_len, unsigned long new_len, 1130 unsigned long flags, unsigned long new_addr) 1131 { 1132 struct vm_area_struct *vma; 1133 1134 /* insanity checks first */ 1135 if (new_len == 0) 1136 return (unsigned long) -EINVAL; 1137 1138 if (flags & MREMAP_FIXED && new_addr != addr) 1139 return (unsigned long) -EINVAL; 1140 1141 vma = find_vma_exact(current->mm, addr); 1142 if (!vma) 1143 return (unsigned long) -EINVAL; 1144 1145 if (vma->vm_end != vma->vm_start + old_len) 1146 return (unsigned long) -EFAULT; 1147 1148 if (vma->vm_flags & VM_MAYSHARE) 1149 return (unsigned long) -EPERM; 1150 1151 if (new_len > kobjsize((void *) addr)) 1152 return (unsigned long) -ENOMEM; 1153 1154 /* all checks complete - do it */ 1155 vma->vm_end = vma->vm_start + new_len; 1156 1157 askedalloc -= old_len; 1158 askedalloc += new_len; 1159 1160 return vma->vm_start; 1161 } 1162 1163 asmlinkage unsigned long sys_mremap(unsigned long addr, 1164 unsigned long old_len, unsigned long new_len, 1165 unsigned long flags, unsigned long new_addr) 1166 { 1167 unsigned long ret; 1168 1169 down_write(¤t->mm->mmap_sem); 1170 ret = do_mremap(addr, old_len, new_len, flags, new_addr); 1171 up_write(¤t->mm->mmap_sem); 1172 return ret; 1173 } 1174 1175 struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1176 unsigned int foll_flags) 1177 { 1178 return NULL; 1179 } 1180 1181 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 1182 unsigned long to, unsigned long size, pgprot_t prot) 1183 { 1184 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT; 1185 return 0; 1186 } 1187 EXPORT_SYMBOL(remap_pfn_range); 1188 1189 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) 1190 { 1191 } 1192 1193 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, 1194 unsigned long len, unsigned long pgoff, unsigned long flags) 1195 { 1196 return -ENOMEM; 1197 } 1198 1199 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1200 { 1201 } 1202 1203 void unmap_mapping_range(struct address_space *mapping, 1204 loff_t const holebegin, loff_t const holelen, 1205 int even_cows) 1206 { 1207 } 1208 EXPORT_SYMBOL(unmap_mapping_range); 1209 1210 /* 1211 * ask for an unmapped area at which to create a mapping on a file 1212 */ 1213 unsigned long get_unmapped_area(struct file *file, unsigned long addr, 1214 unsigned long len, unsigned long pgoff, 1215 unsigned long flags) 1216 { 1217 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, 1218 unsigned long, unsigned long); 1219 1220 get_area = current->mm->get_unmapped_area; 1221 if (file && file->f_op && file->f_op->get_unmapped_area) 1222 get_area = file->f_op->get_unmapped_area; 1223 1224 if (!get_area) 1225 return -ENOSYS; 1226 1227 return get_area(file, addr, len, pgoff, flags); 1228 } 1229 1230 EXPORT_SYMBOL(get_unmapped_area); 1231 1232 /* 1233 * Check that a process has enough memory to allocate a new virtual 1234 * mapping. 0 means there is enough memory for the allocation to 1235 * succeed and -ENOMEM implies there is not. 1236 * 1237 * We currently support three overcommit policies, which are set via the 1238 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 1239 * 1240 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 1241 * Additional code 2002 Jul 20 by Robert Love. 1242 * 1243 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 1244 * 1245 * Note this is a helper function intended to be used by LSMs which 1246 * wish to use this logic. 1247 */ 1248 int __vm_enough_memory(long pages, int cap_sys_admin) 1249 { 1250 unsigned long free, allowed; 1251 1252 vm_acct_memory(pages); 1253 1254 /* 1255 * Sometimes we want to use more memory than we have 1256 */ 1257 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 1258 return 0; 1259 1260 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 1261 unsigned long n; 1262 1263 free = global_page_state(NR_FILE_PAGES); 1264 free += nr_swap_pages; 1265 1266 /* 1267 * Any slabs which are created with the 1268 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 1269 * which are reclaimable, under pressure. The dentry 1270 * cache and most inode caches should fall into this 1271 */ 1272 free += global_page_state(NR_SLAB_RECLAIMABLE); 1273 1274 /* 1275 * Leave the last 3% for root 1276 */ 1277 if (!cap_sys_admin) 1278 free -= free / 32; 1279 1280 if (free > pages) 1281 return 0; 1282 1283 /* 1284 * nr_free_pages() is very expensive on large systems, 1285 * only call if we're about to fail. 1286 */ 1287 n = nr_free_pages(); 1288 1289 /* 1290 * Leave reserved pages. The pages are not for anonymous pages. 1291 */ 1292 if (n <= totalreserve_pages) 1293 goto error; 1294 else 1295 n -= totalreserve_pages; 1296 1297 /* 1298 * Leave the last 3% for root 1299 */ 1300 if (!cap_sys_admin) 1301 n -= n / 32; 1302 free += n; 1303 1304 if (free > pages) 1305 return 0; 1306 1307 goto error; 1308 } 1309 1310 allowed = totalram_pages * sysctl_overcommit_ratio / 100; 1311 /* 1312 * Leave the last 3% for root 1313 */ 1314 if (!cap_sys_admin) 1315 allowed -= allowed / 32; 1316 allowed += total_swap_pages; 1317 1318 /* Don't let a single process grow too big: 1319 leave 3% of the size of this process for other processes */ 1320 allowed -= current->mm->total_vm / 32; 1321 1322 /* 1323 * cast `allowed' as a signed long because vm_committed_space 1324 * sometimes has a negative value 1325 */ 1326 if (atomic_read(&vm_committed_space) < (long)allowed) 1327 return 0; 1328 error: 1329 vm_unacct_memory(pages); 1330 1331 return -ENOMEM; 1332 } 1333 1334 int in_gate_area_no_task(unsigned long addr) 1335 { 1336 return 0; 1337 } 1338 1339 struct page *filemap_nopage(struct vm_area_struct *area, 1340 unsigned long address, int *type) 1341 { 1342 BUG(); 1343 return NULL; 1344 } 1345 1346 /* 1347 * Access another process' address space. 1348 * - source/target buffer must be kernel space 1349 */ 1350 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 1351 { 1352 struct vm_area_struct *vma; 1353 struct mm_struct *mm; 1354 1355 if (addr + len < addr) 1356 return 0; 1357 1358 mm = get_task_mm(tsk); 1359 if (!mm) 1360 return 0; 1361 1362 down_read(&mm->mmap_sem); 1363 1364 /* the access must start within one of the target process's mappings */ 1365 vma = find_vma(mm, addr); 1366 if (vma) { 1367 /* don't overrun this mapping */ 1368 if (addr + len >= vma->vm_end) 1369 len = vma->vm_end - addr; 1370 1371 /* only read or write mappings where it is permitted */ 1372 if (write && vma->vm_flags & VM_MAYWRITE) 1373 len -= copy_to_user((void *) addr, buf, len); 1374 else if (!write && vma->vm_flags & VM_MAYREAD) 1375 len -= copy_from_user(buf, (void *) addr, len); 1376 else 1377 len = 0; 1378 } else { 1379 len = 0; 1380 } 1381 1382 up_read(&mm->mmap_sem); 1383 mmput(mm); 1384 return len; 1385 } 1386