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(sysctl_max_map_count); 48 EXPORT_SYMBOL(sysctl_overcommit_memory); 49 EXPORT_SYMBOL(sysctl_overcommit_ratio); 50 EXPORT_SYMBOL(vm_committed_space); 51 EXPORT_SYMBOL(__vm_enough_memory); 52 53 /* list of shareable VMAs */ 54 struct rb_root nommu_vma_tree = RB_ROOT; 55 DECLARE_RWSEM(nommu_vma_sem); 56 57 struct vm_operations_struct generic_file_vm_ops = { 58 }; 59 60 EXPORT_SYMBOL(vmalloc); 61 EXPORT_SYMBOL(vfree); 62 EXPORT_SYMBOL(vmalloc_to_page); 63 EXPORT_SYMBOL(vmalloc_32); 64 65 /* 66 * Handle all mappings that got truncated by a "truncate()" 67 * system call. 68 * 69 * NOTE! We have to be ready to update the memory sharing 70 * between the file and the memory map for a potential last 71 * incomplete page. Ugly, but necessary. 72 */ 73 int vmtruncate(struct inode *inode, loff_t offset) 74 { 75 struct address_space *mapping = inode->i_mapping; 76 unsigned long limit; 77 78 if (inode->i_size < offset) 79 goto do_expand; 80 i_size_write(inode, offset); 81 82 truncate_inode_pages(mapping, offset); 83 goto out_truncate; 84 85 do_expand: 86 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 87 if (limit != RLIM_INFINITY && offset > limit) 88 goto out_sig; 89 if (offset > inode->i_sb->s_maxbytes) 90 goto out; 91 i_size_write(inode, offset); 92 93 out_truncate: 94 if (inode->i_op && inode->i_op->truncate) 95 inode->i_op->truncate(inode); 96 return 0; 97 out_sig: 98 send_sig(SIGXFSZ, current, 0); 99 out: 100 return -EFBIG; 101 } 102 103 EXPORT_SYMBOL(vmtruncate); 104 105 /* 106 * Return the total memory allocated for this pointer, not 107 * just what the caller asked for. 108 * 109 * Doesn't have to be accurate, i.e. may have races. 110 */ 111 unsigned int kobjsize(const void *objp) 112 { 113 struct page *page; 114 115 if (!objp || !((page = virt_to_page(objp)))) 116 return 0; 117 118 if (PageSlab(page)) 119 return ksize(objp); 120 121 BUG_ON(page->index < 0); 122 BUG_ON(page->index >= MAX_ORDER); 123 124 return (PAGE_SIZE << page->index); 125 } 126 127 /* 128 * The nommu dodgy version :-) 129 */ 130 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 131 unsigned long start, int len, int write, int force, 132 struct page **pages, struct vm_area_struct **vmas) 133 { 134 int i; 135 static struct vm_area_struct dummy_vma; 136 137 for (i = 0; i < len; i++) { 138 if (pages) { 139 pages[i] = virt_to_page(start); 140 if (pages[i]) 141 page_cache_get(pages[i]); 142 } 143 if (vmas) 144 vmas[i] = &dummy_vma; 145 start += PAGE_SIZE; 146 } 147 return(i); 148 } 149 150 EXPORT_SYMBOL(get_user_pages); 151 152 DEFINE_RWLOCK(vmlist_lock); 153 struct vm_struct *vmlist; 154 155 void vfree(void *addr) 156 { 157 kfree(addr); 158 } 159 160 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) 161 { 162 /* 163 * kmalloc doesn't like __GFP_HIGHMEM for some reason 164 */ 165 return kmalloc(size, gfp_mask & ~__GFP_HIGHMEM); 166 } 167 168 struct page * vmalloc_to_page(void *addr) 169 { 170 return virt_to_page(addr); 171 } 172 173 unsigned long vmalloc_to_pfn(void *addr) 174 { 175 return page_to_pfn(virt_to_page(addr)); 176 } 177 178 179 long vread(char *buf, char *addr, unsigned long count) 180 { 181 memcpy(buf, addr, count); 182 return count; 183 } 184 185 long vwrite(char *buf, char *addr, unsigned long count) 186 { 187 /* Don't allow overflow */ 188 if ((unsigned long) addr + count < count) 189 count = -(unsigned long) addr; 190 191 memcpy(addr, buf, count); 192 return(count); 193 } 194 195 /* 196 * vmalloc - allocate virtually continguos memory 197 * 198 * @size: allocation size 199 * 200 * Allocate enough pages to cover @size from the page level 201 * allocator and map them into continguos kernel virtual space. 202 * 203 * For tight cotrol over page level allocator and protection flags 204 * use __vmalloc() instead. 205 */ 206 void *vmalloc(unsigned long size) 207 { 208 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); 209 } 210 211 /* 212 * vmalloc_32 - allocate virtually continguos memory (32bit addressable) 213 * 214 * @size: allocation size 215 * 216 * Allocate enough 32bit PA addressable pages to cover @size from the 217 * page level allocator and map them into continguos kernel virtual space. 218 */ 219 void *vmalloc_32(unsigned long size) 220 { 221 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); 222 } 223 224 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 225 { 226 BUG(); 227 return NULL; 228 } 229 230 void vunmap(void *addr) 231 { 232 BUG(); 233 } 234 235 /* 236 * sys_brk() for the most part doesn't need the global kernel 237 * lock, except when an application is doing something nasty 238 * like trying to un-brk an area that has already been mapped 239 * to a regular file. in this case, the unmapping will need 240 * to invoke file system routines that need the global lock. 241 */ 242 asmlinkage unsigned long sys_brk(unsigned long brk) 243 { 244 struct mm_struct *mm = current->mm; 245 246 if (brk < mm->start_brk || brk > mm->context.end_brk) 247 return mm->brk; 248 249 if (mm->brk == brk) 250 return mm->brk; 251 252 /* 253 * Always allow shrinking brk 254 */ 255 if (brk <= mm->brk) { 256 mm->brk = brk; 257 return brk; 258 } 259 260 /* 261 * Ok, looks good - let it rip. 262 */ 263 return mm->brk = brk; 264 } 265 266 #ifdef DEBUG 267 static void show_process_blocks(void) 268 { 269 struct vm_list_struct *vml; 270 271 printk("Process blocks %d:", current->pid); 272 273 for (vml = ¤t->mm->context.vmlist; vml; vml = vml->next) { 274 printk(" %p: %p", vml, vml->vma); 275 if (vml->vma) 276 printk(" (%d @%lx #%d)", 277 kobjsize((void *) vml->vma->vm_start), 278 vml->vma->vm_start, 279 atomic_read(&vml->vma->vm_usage)); 280 printk(vml->next ? " ->" : ".\n"); 281 } 282 } 283 #endif /* DEBUG */ 284 285 static inline struct vm_area_struct *find_nommu_vma(unsigned long start) 286 { 287 struct vm_area_struct *vma; 288 struct rb_node *n = nommu_vma_tree.rb_node; 289 290 while (n) { 291 vma = rb_entry(n, struct vm_area_struct, vm_rb); 292 293 if (start < vma->vm_start) 294 n = n->rb_left; 295 else if (start > vma->vm_start) 296 n = n->rb_right; 297 else 298 return vma; 299 } 300 301 return NULL; 302 } 303 304 static void add_nommu_vma(struct vm_area_struct *vma) 305 { 306 struct vm_area_struct *pvma; 307 struct address_space *mapping; 308 struct rb_node **p = &nommu_vma_tree.rb_node; 309 struct rb_node *parent = NULL; 310 311 /* add the VMA to the mapping */ 312 if (vma->vm_file) { 313 mapping = vma->vm_file->f_mapping; 314 315 flush_dcache_mmap_lock(mapping); 316 vma_prio_tree_insert(vma, &mapping->i_mmap); 317 flush_dcache_mmap_unlock(mapping); 318 } 319 320 /* add the VMA to the master list */ 321 while (*p) { 322 parent = *p; 323 pvma = rb_entry(parent, struct vm_area_struct, vm_rb); 324 325 if (vma->vm_start < pvma->vm_start) { 326 p = &(*p)->rb_left; 327 } 328 else if (vma->vm_start > pvma->vm_start) { 329 p = &(*p)->rb_right; 330 } 331 else { 332 /* mappings are at the same address - this can only 333 * happen for shared-mem chardevs and shared file 334 * mappings backed by ramfs/tmpfs */ 335 BUG_ON(!(pvma->vm_flags & VM_SHARED)); 336 337 if (vma < pvma) 338 p = &(*p)->rb_left; 339 else if (vma > pvma) 340 p = &(*p)->rb_right; 341 else 342 BUG(); 343 } 344 } 345 346 rb_link_node(&vma->vm_rb, parent, p); 347 rb_insert_color(&vma->vm_rb, &nommu_vma_tree); 348 } 349 350 static void delete_nommu_vma(struct vm_area_struct *vma) 351 { 352 struct address_space *mapping; 353 354 /* remove the VMA from the mapping */ 355 if (vma->vm_file) { 356 mapping = vma->vm_file->f_mapping; 357 358 flush_dcache_mmap_lock(mapping); 359 vma_prio_tree_remove(vma, &mapping->i_mmap); 360 flush_dcache_mmap_unlock(mapping); 361 } 362 363 /* remove from the master list */ 364 rb_erase(&vma->vm_rb, &nommu_vma_tree); 365 } 366 367 /* 368 * determine whether a mapping should be permitted and, if so, what sort of 369 * mapping we're capable of supporting 370 */ 371 static int validate_mmap_request(struct file *file, 372 unsigned long addr, 373 unsigned long len, 374 unsigned long prot, 375 unsigned long flags, 376 unsigned long pgoff, 377 unsigned long *_capabilities) 378 { 379 unsigned long capabilities; 380 unsigned long reqprot = prot; 381 int ret; 382 383 /* do the simple checks first */ 384 if (flags & MAP_FIXED || addr) { 385 printk(KERN_DEBUG 386 "%d: Can't do fixed-address/overlay mmap of RAM\n", 387 current->pid); 388 return -EINVAL; 389 } 390 391 if ((flags & MAP_TYPE) != MAP_PRIVATE && 392 (flags & MAP_TYPE) != MAP_SHARED) 393 return -EINVAL; 394 395 if (PAGE_ALIGN(len) == 0) 396 return addr; 397 398 if (len > TASK_SIZE) 399 return -EINVAL; 400 401 /* offset overflow? */ 402 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 403 return -EINVAL; 404 405 if (file) { 406 /* validate file mapping requests */ 407 struct address_space *mapping; 408 409 /* files must support mmap */ 410 if (!file->f_op || !file->f_op->mmap) 411 return -ENODEV; 412 413 /* work out if what we've got could possibly be shared 414 * - we support chardevs that provide their own "memory" 415 * - we support files/blockdevs that are memory backed 416 */ 417 mapping = file->f_mapping; 418 if (!mapping) 419 mapping = file->f_dentry->d_inode->i_mapping; 420 421 capabilities = 0; 422 if (mapping && mapping->backing_dev_info) 423 capabilities = mapping->backing_dev_info->capabilities; 424 425 if (!capabilities) { 426 /* no explicit capabilities set, so assume some 427 * defaults */ 428 switch (file->f_dentry->d_inode->i_mode & S_IFMT) { 429 case S_IFREG: 430 case S_IFBLK: 431 capabilities = BDI_CAP_MAP_COPY; 432 break; 433 434 case S_IFCHR: 435 capabilities = 436 BDI_CAP_MAP_DIRECT | 437 BDI_CAP_READ_MAP | 438 BDI_CAP_WRITE_MAP; 439 break; 440 441 default: 442 return -EINVAL; 443 } 444 } 445 446 /* eliminate any capabilities that we can't support on this 447 * device */ 448 if (!file->f_op->get_unmapped_area) 449 capabilities &= ~BDI_CAP_MAP_DIRECT; 450 if (!file->f_op->read) 451 capabilities &= ~BDI_CAP_MAP_COPY; 452 453 if (flags & MAP_SHARED) { 454 /* do checks for writing, appending and locking */ 455 if ((prot & PROT_WRITE) && 456 !(file->f_mode & FMODE_WRITE)) 457 return -EACCES; 458 459 if (IS_APPEND(file->f_dentry->d_inode) && 460 (file->f_mode & FMODE_WRITE)) 461 return -EACCES; 462 463 if (locks_verify_locked(file->f_dentry->d_inode)) 464 return -EAGAIN; 465 466 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 467 return -ENODEV; 468 469 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || 470 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || 471 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) 472 ) { 473 printk("MAP_SHARED not completely supported on !MMU\n"); 474 return -EINVAL; 475 } 476 477 /* we mustn't privatise shared mappings */ 478 capabilities &= ~BDI_CAP_MAP_COPY; 479 } 480 else { 481 /* we're going to read the file into private memory we 482 * allocate */ 483 if (!(capabilities & BDI_CAP_MAP_COPY)) 484 return -ENODEV; 485 486 /* we don't permit a private writable mapping to be 487 * shared with the backing device */ 488 if (prot & PROT_WRITE) 489 capabilities &= ~BDI_CAP_MAP_DIRECT; 490 } 491 492 /* handle executable mappings and implied executable 493 * mappings */ 494 if (file->f_vfsmnt->mnt_flags & MNT_NOEXEC) { 495 if (prot & PROT_EXEC) 496 return -EPERM; 497 } 498 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 499 /* handle implication of PROT_EXEC by PROT_READ */ 500 if (current->personality & READ_IMPLIES_EXEC) { 501 if (capabilities & BDI_CAP_EXEC_MAP) 502 prot |= PROT_EXEC; 503 } 504 } 505 else if ((prot & PROT_READ) && 506 (prot & PROT_EXEC) && 507 !(capabilities & BDI_CAP_EXEC_MAP) 508 ) { 509 /* backing file is not executable, try to copy */ 510 capabilities &= ~BDI_CAP_MAP_DIRECT; 511 } 512 } 513 else { 514 /* anonymous mappings are always memory backed and can be 515 * privately mapped 516 */ 517 capabilities = BDI_CAP_MAP_COPY; 518 519 /* handle PROT_EXEC implication by PROT_READ */ 520 if ((prot & PROT_READ) && 521 (current->personality & READ_IMPLIES_EXEC)) 522 prot |= PROT_EXEC; 523 } 524 525 /* allow the security API to have its say */ 526 ret = security_file_mmap(file, reqprot, prot, flags); 527 if (ret < 0) 528 return ret; 529 530 /* looks okay */ 531 *_capabilities = capabilities; 532 return 0; 533 } 534 535 /* 536 * we've determined that we can make the mapping, now translate what we 537 * now know into VMA flags 538 */ 539 static unsigned long determine_vm_flags(struct file *file, 540 unsigned long prot, 541 unsigned long flags, 542 unsigned long capabilities) 543 { 544 unsigned long vm_flags; 545 546 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); 547 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 548 /* vm_flags |= mm->def_flags; */ 549 550 if (!(capabilities & BDI_CAP_MAP_DIRECT)) { 551 /* attempt to share read-only copies of mapped file chunks */ 552 if (file && !(prot & PROT_WRITE)) 553 vm_flags |= VM_MAYSHARE; 554 } 555 else { 556 /* overlay a shareable mapping on the backing device or inode 557 * if possible - used for chardevs, ramfs/tmpfs/shmfs and 558 * romfs/cramfs */ 559 if (flags & MAP_SHARED) 560 vm_flags |= VM_MAYSHARE | VM_SHARED; 561 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0) 562 vm_flags |= VM_MAYSHARE; 563 } 564 565 /* refuse to let anyone share private mappings with this process if 566 * it's being traced - otherwise breakpoints set in it may interfere 567 * with another untraced process 568 */ 569 if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED)) 570 vm_flags &= ~VM_MAYSHARE; 571 572 return vm_flags; 573 } 574 575 /* 576 * set up a shared mapping on a file 577 */ 578 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len) 579 { 580 int ret; 581 582 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 583 if (ret != -ENOSYS) 584 return ret; 585 586 /* getting an ENOSYS error indicates that direct mmap isn't 587 * possible (as opposed to tried but failed) so we'll fall 588 * through to making a private copy of the data and mapping 589 * that if we can */ 590 return -ENODEV; 591 } 592 593 /* 594 * set up a private mapping or an anonymous shared mapping 595 */ 596 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len) 597 { 598 void *base; 599 int ret; 600 601 /* invoke the file's mapping function so that it can keep track of 602 * shared mappings on devices or memory 603 * - VM_MAYSHARE will be set if it may attempt to share 604 */ 605 if (vma->vm_file) { 606 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 607 if (ret != -ENOSYS) { 608 /* shouldn't return success if we're not sharing */ 609 BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE)); 610 return ret; /* success or a real error */ 611 } 612 613 /* getting an ENOSYS error indicates that direct mmap isn't 614 * possible (as opposed to tried but failed) so we'll try to 615 * make a private copy of the data and map that instead */ 616 } 617 618 /* allocate some memory to hold the mapping 619 * - note that this may not return a page-aligned address if the object 620 * we're allocating is smaller than a page 621 */ 622 base = kmalloc(len, GFP_KERNEL); 623 if (!base) 624 goto enomem; 625 626 vma->vm_start = (unsigned long) base; 627 vma->vm_end = vma->vm_start + len; 628 vma->vm_flags |= VM_MAPPED_COPY; 629 630 #ifdef WARN_ON_SLACK 631 if (len + WARN_ON_SLACK <= kobjsize(result)) 632 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n", 633 len, current->pid, kobjsize(result) - len); 634 #endif 635 636 if (vma->vm_file) { 637 /* read the contents of a file into the copy */ 638 mm_segment_t old_fs; 639 loff_t fpos; 640 641 fpos = vma->vm_pgoff; 642 fpos <<= PAGE_SHIFT; 643 644 old_fs = get_fs(); 645 set_fs(KERNEL_DS); 646 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos); 647 set_fs(old_fs); 648 649 if (ret < 0) 650 goto error_free; 651 652 /* clear the last little bit */ 653 if (ret < len) 654 memset(base + ret, 0, len - ret); 655 656 } else { 657 /* if it's an anonymous mapping, then just clear it */ 658 memset(base, 0, len); 659 } 660 661 return 0; 662 663 error_free: 664 kfree(base); 665 vma->vm_start = 0; 666 return ret; 667 668 enomem: 669 printk("Allocation of length %lu from process %d failed\n", 670 len, current->pid); 671 show_free_areas(); 672 return -ENOMEM; 673 } 674 675 /* 676 * handle mapping creation for uClinux 677 */ 678 unsigned long do_mmap_pgoff(struct file *file, 679 unsigned long addr, 680 unsigned long len, 681 unsigned long prot, 682 unsigned long flags, 683 unsigned long pgoff) 684 { 685 struct vm_list_struct *vml = NULL; 686 struct vm_area_struct *vma = NULL; 687 struct rb_node *rb; 688 unsigned long capabilities, vm_flags; 689 void *result; 690 int ret; 691 692 /* decide whether we should attempt the mapping, and if so what sort of 693 * mapping */ 694 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 695 &capabilities); 696 if (ret < 0) 697 return ret; 698 699 /* we've determined that we can make the mapping, now translate what we 700 * now know into VMA flags */ 701 vm_flags = determine_vm_flags(file, prot, flags, capabilities); 702 703 /* we're going to need to record the mapping if it works */ 704 vml = kmalloc(sizeof(struct vm_list_struct), GFP_KERNEL); 705 if (!vml) 706 goto error_getting_vml; 707 memset(vml, 0, sizeof(*vml)); 708 709 down_write(&nommu_vma_sem); 710 711 /* if we want to share, we need to check for VMAs created by other 712 * mmap() calls that overlap with our proposed mapping 713 * - we can only share with an exact match on most regular files 714 * - shared mappings on character devices and memory backed files are 715 * permitted to overlap inexactly as far as we are concerned for in 716 * these cases, sharing is handled in the driver or filesystem rather 717 * than here 718 */ 719 if (vm_flags & VM_MAYSHARE) { 720 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 721 unsigned long vmpglen; 722 723 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) { 724 vma = rb_entry(rb, struct vm_area_struct, vm_rb); 725 726 if (!(vma->vm_flags & VM_MAYSHARE)) 727 continue; 728 729 /* search for overlapping mappings on the same file */ 730 if (vma->vm_file->f_dentry->d_inode != file->f_dentry->d_inode) 731 continue; 732 733 if (vma->vm_pgoff >= pgoff + pglen) 734 continue; 735 736 vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1; 737 vmpglen >>= PAGE_SHIFT; 738 if (pgoff >= vma->vm_pgoff + vmpglen) 739 continue; 740 741 /* handle inexactly overlapping matches between mappings */ 742 if (vma->vm_pgoff != pgoff || vmpglen != pglen) { 743 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 744 goto sharing_violation; 745 continue; 746 } 747 748 /* we've found a VMA we can share */ 749 atomic_inc(&vma->vm_usage); 750 751 vml->vma = vma; 752 result = (void *) vma->vm_start; 753 goto shared; 754 } 755 756 vma = NULL; 757 758 /* obtain the address at which to make a shared mapping 759 * - this is the hook for quasi-memory character devices to 760 * tell us the location of a shared mapping 761 */ 762 if (file && file->f_op->get_unmapped_area) { 763 addr = file->f_op->get_unmapped_area(file, addr, len, 764 pgoff, flags); 765 if (IS_ERR((void *) addr)) { 766 ret = addr; 767 if (ret != (unsigned long) -ENOSYS) 768 goto error; 769 770 /* the driver refused to tell us where to site 771 * the mapping so we'll have to attempt to copy 772 * it */ 773 ret = (unsigned long) -ENODEV; 774 if (!(capabilities & BDI_CAP_MAP_COPY)) 775 goto error; 776 777 capabilities &= ~BDI_CAP_MAP_DIRECT; 778 } 779 } 780 } 781 782 /* we're going to need a VMA struct as well */ 783 vma = kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL); 784 if (!vma) 785 goto error_getting_vma; 786 787 memset(vma, 0, sizeof(*vma)); 788 INIT_LIST_HEAD(&vma->anon_vma_node); 789 atomic_set(&vma->vm_usage, 1); 790 if (file) 791 get_file(file); 792 vma->vm_file = file; 793 vma->vm_flags = vm_flags; 794 vma->vm_start = addr; 795 vma->vm_end = addr + len; 796 vma->vm_pgoff = pgoff; 797 798 vml->vma = vma; 799 800 /* set up the mapping */ 801 if (file && vma->vm_flags & VM_SHARED) 802 ret = do_mmap_shared_file(vma, len); 803 else 804 ret = do_mmap_private(vma, len); 805 if (ret < 0) 806 goto error; 807 808 /* okay... we have a mapping; now we have to register it */ 809 result = (void *) vma->vm_start; 810 811 if (vma->vm_flags & VM_MAPPED_COPY) { 812 realalloc += kobjsize(result); 813 askedalloc += len; 814 } 815 816 realalloc += kobjsize(vma); 817 askedalloc += sizeof(*vma); 818 819 current->mm->total_vm += len >> PAGE_SHIFT; 820 821 add_nommu_vma(vma); 822 823 shared: 824 realalloc += kobjsize(vml); 825 askedalloc += sizeof(*vml); 826 827 vml->next = current->mm->context.vmlist; 828 current->mm->context.vmlist = vml; 829 830 up_write(&nommu_vma_sem); 831 832 if (prot & PROT_EXEC) 833 flush_icache_range((unsigned long) result, 834 (unsigned long) result + len); 835 836 #ifdef DEBUG 837 printk("do_mmap:\n"); 838 show_process_blocks(); 839 #endif 840 841 return (unsigned long) result; 842 843 error: 844 up_write(&nommu_vma_sem); 845 kfree(vml); 846 if (vma) { 847 fput(vma->vm_file); 848 kfree(vma); 849 } 850 return ret; 851 852 sharing_violation: 853 up_write(&nommu_vma_sem); 854 printk("Attempt to share mismatched mappings\n"); 855 kfree(vml); 856 return -EINVAL; 857 858 error_getting_vma: 859 up_write(&nommu_vma_sem); 860 kfree(vml); 861 printk("Allocation of vma for %lu byte allocation from process %d failed\n", 862 len, current->pid); 863 show_free_areas(); 864 return -ENOMEM; 865 866 error_getting_vml: 867 printk("Allocation of vml for %lu byte allocation from process %d failed\n", 868 len, current->pid); 869 show_free_areas(); 870 return -ENOMEM; 871 } 872 873 /* 874 * handle mapping disposal for uClinux 875 */ 876 static void put_vma(struct vm_area_struct *vma) 877 { 878 if (vma) { 879 down_write(&nommu_vma_sem); 880 881 if (atomic_dec_and_test(&vma->vm_usage)) { 882 delete_nommu_vma(vma); 883 884 if (vma->vm_ops && vma->vm_ops->close) 885 vma->vm_ops->close(vma); 886 887 /* IO memory and memory shared directly out of the pagecache from 888 * ramfs/tmpfs mustn't be released here */ 889 if (vma->vm_flags & VM_MAPPED_COPY) { 890 realalloc -= kobjsize((void *) vma->vm_start); 891 askedalloc -= vma->vm_end - vma->vm_start; 892 kfree((void *) vma->vm_start); 893 } 894 895 realalloc -= kobjsize(vma); 896 askedalloc -= sizeof(*vma); 897 898 if (vma->vm_file) 899 fput(vma->vm_file); 900 kfree(vma); 901 } 902 903 up_write(&nommu_vma_sem); 904 } 905 } 906 907 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len) 908 { 909 struct vm_list_struct *vml, **parent; 910 unsigned long end = addr + len; 911 912 #ifdef DEBUG 913 printk("do_munmap:\n"); 914 #endif 915 916 for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) 917 if ((*parent)->vma->vm_start == addr && 918 ((len == 0) || ((*parent)->vma->vm_end == end))) 919 goto found; 920 921 printk("munmap of non-mmaped memory by process %d (%s): %p\n", 922 current->pid, current->comm, (void *) addr); 923 return -EINVAL; 924 925 found: 926 vml = *parent; 927 928 put_vma(vml->vma); 929 930 *parent = vml->next; 931 realalloc -= kobjsize(vml); 932 askedalloc -= sizeof(*vml); 933 kfree(vml); 934 935 update_hiwater_vm(mm); 936 mm->total_vm -= len >> PAGE_SHIFT; 937 938 #ifdef DEBUG 939 show_process_blocks(); 940 #endif 941 942 return 0; 943 } 944 945 /* Release all mmaps. */ 946 void exit_mmap(struct mm_struct * mm) 947 { 948 struct vm_list_struct *tmp; 949 950 if (mm) { 951 #ifdef DEBUG 952 printk("Exit_mmap:\n"); 953 #endif 954 955 mm->total_vm = 0; 956 957 while ((tmp = mm->context.vmlist)) { 958 mm->context.vmlist = tmp->next; 959 put_vma(tmp->vma); 960 961 realalloc -= kobjsize(tmp); 962 askedalloc -= sizeof(*tmp); 963 kfree(tmp); 964 } 965 966 #ifdef DEBUG 967 show_process_blocks(); 968 #endif 969 } 970 } 971 972 asmlinkage long sys_munmap(unsigned long addr, size_t len) 973 { 974 int ret; 975 struct mm_struct *mm = current->mm; 976 977 down_write(&mm->mmap_sem); 978 ret = do_munmap(mm, addr, len); 979 up_write(&mm->mmap_sem); 980 return ret; 981 } 982 983 unsigned long do_brk(unsigned long addr, unsigned long len) 984 { 985 return -ENOMEM; 986 } 987 988 /* 989 * Expand (or shrink) an existing mapping, potentially moving it at the 990 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) 991 * 992 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise 993 * This option implies MREMAP_MAYMOVE. 994 * 995 * on uClinux, we only permit changing a mapping's size, and only as long as it stays within the 996 * hole allocated by the kmalloc() call in do_mmap_pgoff() and the block is not shareable 997 */ 998 unsigned long do_mremap(unsigned long addr, 999 unsigned long old_len, unsigned long new_len, 1000 unsigned long flags, unsigned long new_addr) 1001 { 1002 struct vm_list_struct *vml = NULL; 1003 1004 /* insanity checks first */ 1005 if (new_len == 0) 1006 return (unsigned long) -EINVAL; 1007 1008 if (flags & MREMAP_FIXED && new_addr != addr) 1009 return (unsigned long) -EINVAL; 1010 1011 for (vml = current->mm->context.vmlist; vml; vml = vml->next) 1012 if (vml->vma->vm_start == addr) 1013 goto found; 1014 1015 return (unsigned long) -EINVAL; 1016 1017 found: 1018 if (vml->vma->vm_end != vml->vma->vm_start + old_len) 1019 return (unsigned long) -EFAULT; 1020 1021 if (vml->vma->vm_flags & VM_MAYSHARE) 1022 return (unsigned long) -EPERM; 1023 1024 if (new_len > kobjsize((void *) addr)) 1025 return (unsigned long) -ENOMEM; 1026 1027 /* all checks complete - do it */ 1028 vml->vma->vm_end = vml->vma->vm_start + new_len; 1029 1030 askedalloc -= old_len; 1031 askedalloc += new_len; 1032 1033 return vml->vma->vm_start; 1034 } 1035 1036 /* 1037 * Look up the first VMA which satisfies addr < vm_end, NULL if none 1038 */ 1039 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 1040 { 1041 struct vm_list_struct *vml; 1042 1043 for (vml = mm->context.vmlist; vml; vml = vml->next) 1044 if (addr >= vml->vma->vm_start && addr < vml->vma->vm_end) 1045 return vml->vma; 1046 1047 return NULL; 1048 } 1049 1050 EXPORT_SYMBOL(find_vma); 1051 1052 struct page *follow_page(struct mm_struct *mm, unsigned long address, 1053 unsigned int foll_flags) 1054 { 1055 return NULL; 1056 } 1057 1058 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) 1059 { 1060 return NULL; 1061 } 1062 1063 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 1064 unsigned long to, unsigned long size, pgprot_t prot) 1065 { 1066 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT; 1067 return 0; 1068 } 1069 1070 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) 1071 { 1072 } 1073 1074 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, 1075 unsigned long len, unsigned long pgoff, unsigned long flags) 1076 { 1077 return -ENOMEM; 1078 } 1079 1080 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1081 { 1082 } 1083 1084 void unmap_mapping_range(struct address_space *mapping, 1085 loff_t const holebegin, loff_t const holelen, 1086 int even_cows) 1087 { 1088 } 1089 1090 /* 1091 * Check that a process has enough memory to allocate a new virtual 1092 * mapping. 0 means there is enough memory for the allocation to 1093 * succeed and -ENOMEM implies there is not. 1094 * 1095 * We currently support three overcommit policies, which are set via the 1096 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 1097 * 1098 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 1099 * Additional code 2002 Jul 20 by Robert Love. 1100 * 1101 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 1102 * 1103 * Note this is a helper function intended to be used by LSMs which 1104 * wish to use this logic. 1105 */ 1106 int __vm_enough_memory(long pages, int cap_sys_admin) 1107 { 1108 unsigned long free, allowed; 1109 1110 vm_acct_memory(pages); 1111 1112 /* 1113 * Sometimes we want to use more memory than we have 1114 */ 1115 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 1116 return 0; 1117 1118 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 1119 unsigned long n; 1120 1121 free = get_page_cache_size(); 1122 free += nr_swap_pages; 1123 1124 /* 1125 * Any slabs which are created with the 1126 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 1127 * which are reclaimable, under pressure. The dentry 1128 * cache and most inode caches should fall into this 1129 */ 1130 free += atomic_read(&slab_reclaim_pages); 1131 1132 /* 1133 * Leave the last 3% for root 1134 */ 1135 if (!cap_sys_admin) 1136 free -= free / 32; 1137 1138 if (free > pages) 1139 return 0; 1140 1141 /* 1142 * nr_free_pages() is very expensive on large systems, 1143 * only call if we're about to fail. 1144 */ 1145 n = nr_free_pages(); 1146 if (!cap_sys_admin) 1147 n -= n / 32; 1148 free += n; 1149 1150 if (free > pages) 1151 return 0; 1152 vm_unacct_memory(pages); 1153 return -ENOMEM; 1154 } 1155 1156 allowed = totalram_pages * sysctl_overcommit_ratio / 100; 1157 /* 1158 * Leave the last 3% for root 1159 */ 1160 if (!cap_sys_admin) 1161 allowed -= allowed / 32; 1162 allowed += total_swap_pages; 1163 1164 /* Don't let a single process grow too big: 1165 leave 3% of the size of this process for other processes */ 1166 allowed -= current->mm->total_vm / 32; 1167 1168 /* 1169 * cast `allowed' as a signed long because vm_committed_space 1170 * sometimes has a negative value 1171 */ 1172 if (atomic_read(&vm_committed_space) < (long)allowed) 1173 return 0; 1174 1175 vm_unacct_memory(pages); 1176 1177 return -ENOMEM; 1178 } 1179 1180 int in_gate_area_no_task(unsigned long addr) 1181 { 1182 return 0; 1183 } 1184