1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/mm/nommu.c
   4 *
   5 *  Replacement code for mm functions to support CPU's that don't
   6 *  have any form of memory management unit (thus no virtual memory).
   7 *
   8 *  See Documentation/nommu-mmap.txt
   9 *
  10 *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
  11 *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
  12 *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
  13 *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
  14 *  Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
  15 */
  16
  17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19#include <linux/export.h>
  20#include <linux/mm.h>
  21#include <linux/sched/mm.h>
  22#include <linux/vmacache.h>
  23#include <linux/mman.h>
  24#include <linux/swap.h>
  25#include <linux/file.h>
  26#include <linux/highmem.h>
  27#include <linux/pagemap.h>
  28#include <linux/slab.h>
  29#include <linux/vmalloc.h>
  30#include <linux/blkdev.h>
  31#include <linux/backing-dev.h>
  32#include <linux/compiler.h>
  33#include <linux/mount.h>
  34#include <linux/personality.h>
  35#include <linux/security.h>
  36#include <linux/syscalls.h>
  37#include <linux/audit.h>
  38#include <linux/printk.h>
  39
  40#include <linux/uaccess.h>
 
  41#include <asm/tlb.h>
  42#include <asm/tlbflush.h>
  43#include <asm/mmu_context.h>
  44#include "internal.h"
  45
  46void *high_memory;
  47EXPORT_SYMBOL(high_memory);
  48struct page *mem_map;
  49unsigned long max_mapnr;
  50EXPORT_SYMBOL(max_mapnr);
  51unsigned long highest_memmap_pfn;
  52int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
  53int heap_stack_gap = 0;
  54
  55atomic_long_t mmap_pages_allocated;
  56
  57EXPORT_SYMBOL(mem_map);
  58
  59/* list of mapped, potentially shareable regions */
  60static struct kmem_cache *vm_region_jar;
  61struct rb_root nommu_region_tree = RB_ROOT;
  62DECLARE_RWSEM(nommu_region_sem);
  63
  64const struct vm_operations_struct generic_file_vm_ops = {
  65};
  66
  67/*
  68 * Return the total memory allocated for this pointer, not
  69 * just what the caller asked for.
  70 *
  71 * Doesn't have to be accurate, i.e. may have races.
  72 */
  73unsigned int kobjsize(const void *objp)
  74{
  75	struct page *page;
  76
  77	/*
  78	 * If the object we have should not have ksize performed on it,
  79	 * return size of 0
  80	 */
  81	if (!objp || !virt_addr_valid(objp))
  82		return 0;
  83
  84	page = virt_to_head_page(objp);
  85
  86	/*
  87	 * If the allocator sets PageSlab, we know the pointer came from
  88	 * kmalloc().
  89	 */
  90	if (PageSlab(page))
  91		return ksize(objp);
  92
  93	/*
  94	 * If it's not a compound page, see if we have a matching VMA
  95	 * region. This test is intentionally done in reverse order,
  96	 * so if there's no VMA, we still fall through and hand back
  97	 * PAGE_SIZE for 0-order pages.
  98	 */
  99	if (!PageCompound(page)) {
 100		struct vm_area_struct *vma;
 101
 102		vma = find_vma(current->mm, (unsigned long)objp);
 103		if (vma)
 104			return vma->vm_end - vma->vm_start;
 105	}
 106
 107	/*
 108	 * The ksize() function is only guaranteed to work for pointers
 109	 * returned by kmalloc(). So handle arbitrary pointers here.
 110	 */
 111	return page_size(page);
 112}
 113
 114/**
 115 * follow_pfn - look up PFN at a user virtual address
 116 * @vma: memory mapping
 117 * @address: user virtual address
 118 * @pfn: location to store found PFN
 119 *
 120 * Only IO mappings and raw PFN mappings are allowed.
 121 *
 122 * Returns zero and the pfn at @pfn on success, -ve otherwise.
 123 */
 124int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 125	unsigned long *pfn)
 126{
 127	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 128		return -EINVAL;
 129
 130	*pfn = address >> PAGE_SHIFT;
 131	return 0;
 132}
 133EXPORT_SYMBOL(follow_pfn);
 134
 135LIST_HEAD(vmap_area_list);
 136
 137void vfree(const void *addr)
 138{
 139	kfree(addr);
 140}
 141EXPORT_SYMBOL(vfree);
 142
 143void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 144{
 145	/*
 146	 *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 147	 * returns only a logical address.
 148	 */
 149	return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 150}
 151EXPORT_SYMBOL(__vmalloc);
 152
 153void *__vmalloc_node_flags(unsigned long size, int node, gfp_t flags)
 
 
 
 154{
 155	return __vmalloc(size, flags, PAGE_KERNEL);
 156}
 157
 158void *vmalloc_user(unsigned long size)
 
 
 
 
 
 
 159{
 160	void *ret;
 161
 162	ret = __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
 163	if (ret) {
 164		struct vm_area_struct *vma;
 165
 166		down_write(&current->mm->mmap_sem);
 167		vma = find_vma(current->mm, (unsigned long)ret);
 168		if (vma)
 169			vma->vm_flags |= VM_USERMAP;
 170		up_write(&current->mm->mmap_sem);
 171	}
 172
 173	return ret;
 174}
 
 
 
 
 
 175EXPORT_SYMBOL(vmalloc_user);
 176
 177struct page *vmalloc_to_page(const void *addr)
 178{
 179	return virt_to_page(addr);
 180}
 181EXPORT_SYMBOL(vmalloc_to_page);
 182
 183unsigned long vmalloc_to_pfn(const void *addr)
 184{
 185	return page_to_pfn(virt_to_page(addr));
 186}
 187EXPORT_SYMBOL(vmalloc_to_pfn);
 188
 189long vread(char *buf, char *addr, unsigned long count)
 190{
 191	/* Don't allow overflow */
 192	if ((unsigned long) buf + count < count)
 193		count = -(unsigned long) buf;
 194
 195	memcpy(buf, addr, count);
 196	return count;
 197}
 198
 199long vwrite(char *buf, char *addr, unsigned long count)
 200{
 201	/* Don't allow overflow */
 202	if ((unsigned long) addr + count < count)
 203		count = -(unsigned long) addr;
 204
 205	memcpy(addr, buf, count);
 206	return count;
 207}
 208
 209/*
 210 *	vmalloc  -  allocate virtually contiguous memory
 211 *
 212 *	@size:		allocation size
 213 *
 214 *	Allocate enough pages to cover @size from the page level
 215 *	allocator and map them into contiguous kernel virtual space.
 216 *
 217 *	For tight control over page level allocator and protection flags
 218 *	use __vmalloc() instead.
 219 */
 220void *vmalloc(unsigned long size)
 221{
 222       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 223}
 224EXPORT_SYMBOL(vmalloc);
 225
 
 
 226/*
 227 *	vzalloc - allocate virtually contiguous memory with zero fill
 228 *
 229 *	@size:		allocation size
 230 *
 231 *	Allocate enough pages to cover @size from the page level
 232 *	allocator and map them into contiguous kernel virtual space.
 233 *	The memory allocated is set to zero.
 234 *
 235 *	For tight control over page level allocator and protection flags
 236 *	use __vmalloc() instead.
 237 */
 238void *vzalloc(unsigned long size)
 239{
 240	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 241			PAGE_KERNEL);
 242}
 243EXPORT_SYMBOL(vzalloc);
 244
 245/**
 246 * vmalloc_node - allocate memory on a specific node
 247 * @size:	allocation size
 248 * @node:	numa node
 249 *
 250 * Allocate enough pages to cover @size from the page level
 251 * allocator and map them into contiguous kernel virtual space.
 252 *
 253 * For tight control over page level allocator and protection flags
 254 * use __vmalloc() instead.
 255 */
 256void *vmalloc_node(unsigned long size, int node)
 257{
 258	return vmalloc(size);
 259}
 260EXPORT_SYMBOL(vmalloc_node);
 261
 262/**
 263 * vzalloc_node - allocate memory on a specific node with zero fill
 264 * @size:	allocation size
 265 * @node:	numa node
 266 *
 267 * Allocate enough pages to cover @size from the page level
 268 * allocator and map them into contiguous kernel virtual space.
 269 * The memory allocated is set to zero.
 270 *
 271 * For tight control over page level allocator and protection flags
 272 * use __vmalloc() instead.
 273 */
 274void *vzalloc_node(unsigned long size, int node)
 275{
 276	return vzalloc(size);
 277}
 278EXPORT_SYMBOL(vzalloc_node);
 279
 280/**
 281 *	vmalloc_exec  -  allocate virtually contiguous, executable memory
 282 *	@size:		allocation size
 283 *
 284 *	Kernel-internal function to allocate enough pages to cover @size
 285 *	the page level allocator and map them into contiguous and
 286 *	executable kernel virtual space.
 287 *
 288 *	For tight control over page level allocator and protection flags
 289 *	use __vmalloc() instead.
 290 */
 291
 292void *vmalloc_exec(unsigned long size)
 293{
 294	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 295}
 296
 297/**
 298 * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 299 *	@size:		allocation size
 300 *
 301 *	Allocate enough 32bit PA addressable pages to cover @size from the
 302 *	page level allocator and map them into contiguous kernel virtual space.
 303 */
 304void *vmalloc_32(unsigned long size)
 305{
 306	return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 307}
 308EXPORT_SYMBOL(vmalloc_32);
 309
 310/**
 311 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 312 *	@size:		allocation size
 313 *
 314 * The resulting memory area is 32bit addressable and zeroed so it can be
 315 * mapped to userspace without leaking data.
 316 *
 317 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 318 * remap_vmalloc_range() are permissible.
 319 */
 320void *vmalloc_32_user(unsigned long size)
 321{
 322	/*
 323	 * We'll have to sort out the ZONE_DMA bits for 64-bit,
 324	 * but for now this can simply use vmalloc_user() directly.
 325	 */
 326	return vmalloc_user(size);
 327}
 328EXPORT_SYMBOL(vmalloc_32_user);
 329
 330void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 331{
 332	BUG();
 333	return NULL;
 334}
 335EXPORT_SYMBOL(vmap);
 336
 337void vunmap(const void *addr)
 338{
 339	BUG();
 340}
 341EXPORT_SYMBOL(vunmap);
 342
 343void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
 344{
 345	BUG();
 346	return NULL;
 347}
 348EXPORT_SYMBOL(vm_map_ram);
 349
 350void vm_unmap_ram(const void *mem, unsigned int count)
 351{
 352	BUG();
 353}
 354EXPORT_SYMBOL(vm_unmap_ram);
 355
 356void vm_unmap_aliases(void)
 357{
 358}
 359EXPORT_SYMBOL_GPL(vm_unmap_aliases);
 360
 361/*
 362 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 363 * have one.
 364 */
 365void __weak vmalloc_sync_all(void)
 366{
 367}
 368
 369struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
 370{
 371	BUG();
 372	return NULL;
 373}
 374EXPORT_SYMBOL_GPL(alloc_vm_area);
 375
 376void free_vm_area(struct vm_struct *area)
 377{
 378	BUG();
 379}
 380EXPORT_SYMBOL_GPL(free_vm_area);
 381
 382int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 383		   struct page *page)
 384{
 385	return -EINVAL;
 386}
 387EXPORT_SYMBOL(vm_insert_page);
 388
 389int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
 390			unsigned long num)
 391{
 392	return -EINVAL;
 393}
 394EXPORT_SYMBOL(vm_map_pages);
 395
 396int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
 397				unsigned long num)
 398{
 399	return -EINVAL;
 400}
 401EXPORT_SYMBOL(vm_map_pages_zero);
 402
 403/*
 404 *  sys_brk() for the most part doesn't need the global kernel
 405 *  lock, except when an application is doing something nasty
 406 *  like trying to un-brk an area that has already been mapped
 407 *  to a regular file.  in this case, the unmapping will need
 408 *  to invoke file system routines that need the global lock.
 409 */
 410SYSCALL_DEFINE1(brk, unsigned long, brk)
 411{
 412	struct mm_struct *mm = current->mm;
 413
 414	if (brk < mm->start_brk || brk > mm->context.end_brk)
 415		return mm->brk;
 416
 417	if (mm->brk == brk)
 418		return mm->brk;
 419
 420	/*
 421	 * Always allow shrinking brk
 422	 */
 423	if (brk <= mm->brk) {
 424		mm->brk = brk;
 425		return brk;
 426	}
 427
 428	/*
 429	 * Ok, looks good - let it rip.
 430	 */
 431	flush_icache_range(mm->brk, brk);
 432	return mm->brk = brk;
 433}
 434
 435/*
 436 * initialise the percpu counter for VM and region record slabs
 437 */
 438void __init mmap_init(void)
 439{
 440	int ret;
 441
 442	ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
 443	VM_BUG_ON(ret);
 444	vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
 445}
 446
 447/*
 448 * validate the region tree
 449 * - the caller must hold the region lock
 450 */
 451#ifdef CONFIG_DEBUG_NOMMU_REGIONS
 452static noinline void validate_nommu_regions(void)
 453{
 454	struct vm_region *region, *last;
 455	struct rb_node *p, *lastp;
 456
 457	lastp = rb_first(&nommu_region_tree);
 458	if (!lastp)
 459		return;
 460
 461	last = rb_entry(lastp, struct vm_region, vm_rb);
 462	BUG_ON(last->vm_end <= last->vm_start);
 463	BUG_ON(last->vm_top < last->vm_end);
 464
 465	while ((p = rb_next(lastp))) {
 466		region = rb_entry(p, struct vm_region, vm_rb);
 467		last = rb_entry(lastp, struct vm_region, vm_rb);
 468
 469		BUG_ON(region->vm_end <= region->vm_start);
 470		BUG_ON(region->vm_top < region->vm_end);
 471		BUG_ON(region->vm_start < last->vm_top);
 472
 473		lastp = p;
 474	}
 475}
 476#else
 477static void validate_nommu_regions(void)
 478{
 479}
 480#endif
 481
 482/*
 483 * add a region into the global tree
 484 */
 485static void add_nommu_region(struct vm_region *region)
 486{
 487	struct vm_region *pregion;
 488	struct rb_node **p, *parent;
 489
 490	validate_nommu_regions();
 491
 492	parent = NULL;
 493	p = &nommu_region_tree.rb_node;
 494	while (*p) {
 495		parent = *p;
 496		pregion = rb_entry(parent, struct vm_region, vm_rb);
 497		if (region->vm_start < pregion->vm_start)
 498			p = &(*p)->rb_left;
 499		else if (region->vm_start > pregion->vm_start)
 500			p = &(*p)->rb_right;
 501		else if (pregion == region)
 502			return;
 503		else
 504			BUG();
 505	}
 506
 507	rb_link_node(&region->vm_rb, parent, p);
 508	rb_insert_color(&region->vm_rb, &nommu_region_tree);
 509
 510	validate_nommu_regions();
 511}
 512
 513/*
 514 * delete a region from the global tree
 515 */
 516static void delete_nommu_region(struct vm_region *region)
 517{
 518	BUG_ON(!nommu_region_tree.rb_node);
 519
 520	validate_nommu_regions();
 521	rb_erase(&region->vm_rb, &nommu_region_tree);
 522	validate_nommu_regions();
 523}
 524
 525/*
 526 * free a contiguous series of pages
 527 */
 528static void free_page_series(unsigned long from, unsigned long to)
 529{
 530	for (; from < to; from += PAGE_SIZE) {
 531		struct page *page = virt_to_page(from);
 532
 533		atomic_long_dec(&mmap_pages_allocated);
 534		put_page(page);
 535	}
 536}
 537
 538/*
 539 * release a reference to a region
 540 * - the caller must hold the region semaphore for writing, which this releases
 541 * - the region may not have been added to the tree yet, in which case vm_top
 542 *   will equal vm_start
 543 */
 544static void __put_nommu_region(struct vm_region *region)
 545	__releases(nommu_region_sem)
 546{
 547	BUG_ON(!nommu_region_tree.rb_node);
 548
 549	if (--region->vm_usage == 0) {
 550		if (region->vm_top > region->vm_start)
 551			delete_nommu_region(region);
 552		up_write(&nommu_region_sem);
 553
 554		if (region->vm_file)
 555			fput(region->vm_file);
 556
 557		/* IO memory and memory shared directly out of the pagecache
 558		 * from ramfs/tmpfs mustn't be released here */
 559		if (region->vm_flags & VM_MAPPED_COPY)
 560			free_page_series(region->vm_start, region->vm_top);
 561		kmem_cache_free(vm_region_jar, region);
 562	} else {
 563		up_write(&nommu_region_sem);
 564	}
 565}
 566
 567/*
 568 * release a reference to a region
 569 */
 570static void put_nommu_region(struct vm_region *region)
 571{
 572	down_write(&nommu_region_sem);
 573	__put_nommu_region(region);
 574}
 575
 576/*
 577 * add a VMA into a process's mm_struct in the appropriate place in the list
 578 * and tree and add to the address space's page tree also if not an anonymous
 579 * page
 580 * - should be called with mm->mmap_sem held writelocked
 581 */
 582static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 583{
 584	struct vm_area_struct *pvma, *prev;
 585	struct address_space *mapping;
 586	struct rb_node **p, *parent, *rb_prev;
 587
 588	BUG_ON(!vma->vm_region);
 589
 590	mm->map_count++;
 591	vma->vm_mm = mm;
 592
 593	/* add the VMA to the mapping */
 594	if (vma->vm_file) {
 595		mapping = vma->vm_file->f_mapping;
 596
 597		i_mmap_lock_write(mapping);
 598		flush_dcache_mmap_lock(mapping);
 599		vma_interval_tree_insert(vma, &mapping->i_mmap);
 600		flush_dcache_mmap_unlock(mapping);
 601		i_mmap_unlock_write(mapping);
 602	}
 603
 604	/* add the VMA to the tree */
 605	parent = rb_prev = NULL;
 606	p = &mm->mm_rb.rb_node;
 607	while (*p) {
 608		parent = *p;
 609		pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 610
 611		/* sort by: start addr, end addr, VMA struct addr in that order
 612		 * (the latter is necessary as we may get identical VMAs) */
 613		if (vma->vm_start < pvma->vm_start)
 614			p = &(*p)->rb_left;
 615		else if (vma->vm_start > pvma->vm_start) {
 616			rb_prev = parent;
 617			p = &(*p)->rb_right;
 618		} else if (vma->vm_end < pvma->vm_end)
 619			p = &(*p)->rb_left;
 620		else if (vma->vm_end > pvma->vm_end) {
 621			rb_prev = parent;
 622			p = &(*p)->rb_right;
 623		} else if (vma < pvma)
 624			p = &(*p)->rb_left;
 625		else if (vma > pvma) {
 626			rb_prev = parent;
 627			p = &(*p)->rb_right;
 628		} else
 629			BUG();
 630	}
 631
 632	rb_link_node(&vma->vm_rb, parent, p);
 633	rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 634
 635	/* add VMA to the VMA list also */
 636	prev = NULL;
 637	if (rb_prev)
 638		prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 639
 640	__vma_link_list(mm, vma, prev, parent);
 641}
 642
 643/*
 644 * delete a VMA from its owning mm_struct and address space
 645 */
 646static void delete_vma_from_mm(struct vm_area_struct *vma)
 647{
 648	int i;
 649	struct address_space *mapping;
 650	struct mm_struct *mm = vma->vm_mm;
 651	struct task_struct *curr = current;
 652
 653	mm->map_count--;
 654	for (i = 0; i < VMACACHE_SIZE; i++) {
 655		/* if the vma is cached, invalidate the entire cache */
 656		if (curr->vmacache.vmas[i] == vma) {
 657			vmacache_invalidate(mm);
 658			break;
 659		}
 660	}
 661
 662	/* remove the VMA from the mapping */
 663	if (vma->vm_file) {
 
 664		mapping = vma->vm_file->f_mapping;
 665
 666		i_mmap_lock_write(mapping);
 667		flush_dcache_mmap_lock(mapping);
 668		vma_interval_tree_remove(vma, &mapping->i_mmap);
 669		flush_dcache_mmap_unlock(mapping);
 670		i_mmap_unlock_write(mapping);
 671	}
 
 672
 673	/* remove from the MM's tree and list */
 674	rb_erase(&vma->vm_rb, &mm->mm_rb);
 
 
 
 
 675
 676	if (vma->vm_prev)
 677		vma->vm_prev->vm_next = vma->vm_next;
 678	else
 679		mm->mmap = vma->vm_next;
 
 
 
 680
 681	if (vma->vm_next)
 682		vma->vm_next->vm_prev = vma->vm_prev;
 
 683}
 684
 685/*
 686 * destroy a VMA record
 687 */
 688static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 689{
 690	if (vma->vm_ops && vma->vm_ops->close)
 691		vma->vm_ops->close(vma);
 692	if (vma->vm_file)
 693		fput(vma->vm_file);
 694	put_nommu_region(vma->vm_region);
 695	vm_area_free(vma);
 696}
 697
 
 
 
 
 
 
 
 
 
 
 
 698/*
 699 * look up the first VMA in which addr resides, NULL if none
 700 * - should be called with mm->mmap_sem at least held readlocked
 701 */
 702struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 703{
 704	struct vm_area_struct *vma;
 705
 706	/* check the cache first */
 707	vma = vmacache_find(mm, addr);
 708	if (likely(vma))
 709		return vma;
 710
 711	/* trawl the list (there may be multiple mappings in which addr
 712	 * resides) */
 713	for (vma = mm->mmap; vma; vma = vma->vm_next) {
 714		if (vma->vm_start > addr)
 715			return NULL;
 716		if (vma->vm_end > addr) {
 717			vmacache_update(addr, vma);
 718			return vma;
 719		}
 720	}
 721
 722	return NULL;
 723}
 724EXPORT_SYMBOL(find_vma);
 725
 726/*
 727 * find a VMA
 728 * - we don't extend stack VMAs under NOMMU conditions
 729 */
 730struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 
 731{
 732	return find_vma(mm, addr);
 
 
 
 
 
 
 733}
 734
 735/*
 736 * expand a stack to a given address
 737 * - not supported under NOMMU conditions
 738 */
 739int expand_stack(struct vm_area_struct *vma, unsigned long address)
 740{
 741	return -ENOMEM;
 742}
 743
 
 
 
 
 
 
 744/*
 745 * look up the first VMA exactly that exactly matches addr
 746 * - should be called with mm->mmap_sem at least held readlocked
 747 */
 748static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 749					     unsigned long addr,
 750					     unsigned long len)
 751{
 752	struct vm_area_struct *vma;
 753	unsigned long end = addr + len;
 
 754
 755	/* check the cache first */
 756	vma = vmacache_find_exact(mm, addr, end);
 757	if (vma)
 758		return vma;
 759
 760	/* trawl the list (there may be multiple mappings in which addr
 761	 * resides) */
 762	for (vma = mm->mmap; vma; vma = vma->vm_next) {
 763		if (vma->vm_start < addr)
 764			continue;
 765		if (vma->vm_start > addr)
 766			return NULL;
 767		if (vma->vm_end == end) {
 768			vmacache_update(addr, vma);
 769			return vma;
 770		}
 771	}
 772
 773	return NULL;
 774}
 775
 776/*
 777 * determine whether a mapping should be permitted and, if so, what sort of
 778 * mapping we're capable of supporting
 779 */
 780static int validate_mmap_request(struct file *file,
 781				 unsigned long addr,
 782				 unsigned long len,
 783				 unsigned long prot,
 784				 unsigned long flags,
 785				 unsigned long pgoff,
 786				 unsigned long *_capabilities)
 787{
 788	unsigned long capabilities, rlen;
 789	int ret;
 790
 791	/* do the simple checks first */
 792	if (flags & MAP_FIXED)
 793		return -EINVAL;
 794
 795	if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 796	    (flags & MAP_TYPE) != MAP_SHARED)
 797		return -EINVAL;
 798
 799	if (!len)
 800		return -EINVAL;
 801
 802	/* Careful about overflows.. */
 803	rlen = PAGE_ALIGN(len);
 804	if (!rlen || rlen > TASK_SIZE)
 805		return -ENOMEM;
 806
 807	/* offset overflow? */
 808	if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
 809		return -EOVERFLOW;
 810
 811	if (file) {
 812		/* files must support mmap */
 813		if (!file->f_op->mmap)
 814			return -ENODEV;
 815
 816		/* work out if what we've got could possibly be shared
 817		 * - we support chardevs that provide their own "memory"
 818		 * - we support files/blockdevs that are memory backed
 819		 */
 820		if (file->f_op->mmap_capabilities) {
 821			capabilities = file->f_op->mmap_capabilities(file);
 822		} else {
 823			/* no explicit capabilities set, so assume some
 824			 * defaults */
 825			switch (file_inode(file)->i_mode & S_IFMT) {
 826			case S_IFREG:
 827			case S_IFBLK:
 828				capabilities = NOMMU_MAP_COPY;
 829				break;
 830
 831			case S_IFCHR:
 832				capabilities =
 833					NOMMU_MAP_DIRECT |
 834					NOMMU_MAP_READ |
 835					NOMMU_MAP_WRITE;
 836				break;
 837
 838			default:
 839				return -EINVAL;
 840			}
 841		}
 842
 843		/* eliminate any capabilities that we can't support on this
 844		 * device */
 845		if (!file->f_op->get_unmapped_area)
 846			capabilities &= ~NOMMU_MAP_DIRECT;
 847		if (!(file->f_mode & FMODE_CAN_READ))
 848			capabilities &= ~NOMMU_MAP_COPY;
 849
 850		/* The file shall have been opened with read permission. */
 851		if (!(file->f_mode & FMODE_READ))
 852			return -EACCES;
 853
 854		if (flags & MAP_SHARED) {
 855			/* do checks for writing, appending and locking */
 856			if ((prot & PROT_WRITE) &&
 857			    !(file->f_mode & FMODE_WRITE))
 858				return -EACCES;
 859
 860			if (IS_APPEND(file_inode(file)) &&
 861			    (file->f_mode & FMODE_WRITE))
 862				return -EACCES;
 863
 864			if (locks_verify_locked(file))
 865				return -EAGAIN;
 866
 867			if (!(capabilities & NOMMU_MAP_DIRECT))
 868				return -ENODEV;
 869
 870			/* we mustn't privatise shared mappings */
 871			capabilities &= ~NOMMU_MAP_COPY;
 872		} else {
 873			/* we're going to read the file into private memory we
 874			 * allocate */
 875			if (!(capabilities & NOMMU_MAP_COPY))
 876				return -ENODEV;
 877
 878			/* we don't permit a private writable mapping to be
 879			 * shared with the backing device */
 880			if (prot & PROT_WRITE)
 881				capabilities &= ~NOMMU_MAP_DIRECT;
 882		}
 883
 884		if (capabilities & NOMMU_MAP_DIRECT) {
 885			if (((prot & PROT_READ)  && !(capabilities & NOMMU_MAP_READ))  ||
 886			    ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
 887			    ((prot & PROT_EXEC)  && !(capabilities & NOMMU_MAP_EXEC))
 888			    ) {
 889				capabilities &= ~NOMMU_MAP_DIRECT;
 890				if (flags & MAP_SHARED) {
 891					pr_warn("MAP_SHARED not completely supported on !MMU\n");
 892					return -EINVAL;
 893				}
 894			}
 895		}
 896
 897		/* handle executable mappings and implied executable
 898		 * mappings */
 899		if (path_noexec(&file->f_path)) {
 900			if (prot & PROT_EXEC)
 901				return -EPERM;
 902		} else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 903			/* handle implication of PROT_EXEC by PROT_READ */
 904			if (current->personality & READ_IMPLIES_EXEC) {
 905				if (capabilities & NOMMU_MAP_EXEC)
 906					prot |= PROT_EXEC;
 907			}
 908		} else if ((prot & PROT_READ) &&
 909			 (prot & PROT_EXEC) &&
 910			 !(capabilities & NOMMU_MAP_EXEC)
 911			 ) {
 912			/* backing file is not executable, try to copy */
 913			capabilities &= ~NOMMU_MAP_DIRECT;
 914		}
 915	} else {
 916		/* anonymous mappings are always memory backed and can be
 917		 * privately mapped
 918		 */
 919		capabilities = NOMMU_MAP_COPY;
 920
 921		/* handle PROT_EXEC implication by PROT_READ */
 922		if ((prot & PROT_READ) &&
 923		    (current->personality & READ_IMPLIES_EXEC))
 924			prot |= PROT_EXEC;
 925	}
 926
 927	/* allow the security API to have its say */
 928	ret = security_mmap_addr(addr);
 929	if (ret < 0)
 930		return ret;
 931
 932	/* looks okay */
 933	*_capabilities = capabilities;
 934	return 0;
 935}
 936
 937/*
 938 * we've determined that we can make the mapping, now translate what we
 939 * now know into VMA flags
 940 */
 941static unsigned long determine_vm_flags(struct file *file,
 942					unsigned long prot,
 943					unsigned long flags,
 944					unsigned long capabilities)
 945{
 946	unsigned long vm_flags;
 947
 948	vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
 949	/* vm_flags |= mm->def_flags; */
 950
 951	if (!(capabilities & NOMMU_MAP_DIRECT)) {
 952		/* attempt to share read-only copies of mapped file chunks */
 
 
 
 953		vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 954		if (file && !(prot & PROT_WRITE))
 955			vm_flags |= VM_MAYSHARE;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 956	} else {
 957		/* overlay a shareable mapping on the backing device or inode
 958		 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 959		 * romfs/cramfs */
 960		vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS);
 961		if (flags & MAP_SHARED)
 962			vm_flags |= VM_SHARED;
 963	}
 964
 965	/* refuse to let anyone share private mappings with this process if
 966	 * it's being traced - otherwise breakpoints set in it may interfere
 967	 * with another untraced process
 968	 */
 969	if ((flags & MAP_PRIVATE) && current->ptrace)
 970		vm_flags &= ~VM_MAYSHARE;
 971
 972	return vm_flags;
 973}
 974
 975/*
 976 * set up a shared mapping on a file (the driver or filesystem provides and
 977 * pins the storage)
 978 */
 979static int do_mmap_shared_file(struct vm_area_struct *vma)
 980{
 981	int ret;
 982
 983	ret = call_mmap(vma->vm_file, vma);
 984	if (ret == 0) {
 985		vma->vm_region->vm_top = vma->vm_region->vm_end;
 986		return 0;
 987	}
 988	if (ret != -ENOSYS)
 989		return ret;
 990
 991	/* getting -ENOSYS indicates that direct mmap isn't possible (as
 992	 * opposed to tried but failed) so we can only give a suitable error as
 993	 * it's not possible to make a private copy if MAP_SHARED was given */
 994	return -ENODEV;
 995}
 996
 997/*
 998 * set up a private mapping or an anonymous shared mapping
 999 */
1000static int do_mmap_private(struct vm_area_struct *vma,
1001			   struct vm_region *region,
1002			   unsigned long len,
1003			   unsigned long capabilities)
1004{
1005	unsigned long total, point;
1006	void *base;
1007	int ret, order;
1008
1009	/* invoke the file's mapping function so that it can keep track of
1010	 * shared mappings on devices or memory
1011	 * - VM_MAYSHARE will be set if it may attempt to share
 
 
1012	 */
1013	if (capabilities & NOMMU_MAP_DIRECT) {
1014		ret = call_mmap(vma->vm_file, vma);
 
 
 
1015		if (ret == 0) {
1016			/* shouldn't return success if we're not sharing */
1017			BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1018			vma->vm_region->vm_top = vma->vm_region->vm_end;
1019			return 0;
1020		}
1021		if (ret != -ENOSYS)
1022			return ret;
1023
1024		/* getting an ENOSYS error indicates that direct mmap isn't
1025		 * possible (as opposed to tried but failed) so we'll try to
1026		 * make a private copy of the data and map that instead */
1027	}
1028
1029
1030	/* allocate some memory to hold the mapping
1031	 * - note that this may not return a page-aligned address if the object
1032	 *   we're allocating is smaller than a page
1033	 */
1034	order = get_order(len);
1035	total = 1 << order;
1036	point = len >> PAGE_SHIFT;
1037
1038	/* we don't want to allocate a power-of-2 sized page set */
1039	if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages)
1040		total = point;
1041
1042	base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
1043	if (!base)
1044		goto enomem;
1045
1046	atomic_long_add(total, &mmap_pages_allocated);
1047
1048	region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
 
1049	region->vm_start = (unsigned long) base;
1050	region->vm_end   = region->vm_start + len;
1051	region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1052
1053	vma->vm_start = region->vm_start;
1054	vma->vm_end   = region->vm_start + len;
1055
1056	if (vma->vm_file) {
1057		/* read the contents of a file into the copy */
1058		loff_t fpos;
1059
1060		fpos = vma->vm_pgoff;
1061		fpos <<= PAGE_SHIFT;
1062
1063		ret = kernel_read(vma->vm_file, base, len, &fpos);
1064		if (ret < 0)
1065			goto error_free;
1066
1067		/* clear the last little bit */
1068		if (ret < len)
1069			memset(base + ret, 0, len - ret);
1070
1071	} else {
1072		vma_set_anonymous(vma);
1073	}
1074
1075	return 0;
1076
1077error_free:
1078	free_page_series(region->vm_start, region->vm_top);
1079	region->vm_start = vma->vm_start = 0;
1080	region->vm_end   = vma->vm_end = 0;
1081	region->vm_top   = 0;
1082	return ret;
1083
1084enomem:
1085	pr_err("Allocation of length %lu from process %d (%s) failed\n",
1086	       len, current->pid, current->comm);
1087	show_free_areas(0, NULL);
1088	return -ENOMEM;
1089}
1090
1091/*
1092 * handle mapping creation for uClinux
1093 */
1094unsigned long do_mmap(struct file *file,
1095			unsigned long addr,
1096			unsigned long len,
1097			unsigned long prot,
1098			unsigned long flags,
1099			vm_flags_t vm_flags,
1100			unsigned long pgoff,
1101			unsigned long *populate,
1102			struct list_head *uf)
1103{
1104	struct vm_area_struct *vma;
1105	struct vm_region *region;
1106	struct rb_node *rb;
1107	unsigned long capabilities, result;
1108	int ret;
 
1109
1110	*populate = 0;
1111
1112	/* decide whether we should attempt the mapping, and if so what sort of
1113	 * mapping */
1114	ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1115				    &capabilities);
1116	if (ret < 0)
1117		return ret;
1118
1119	/* we ignore the address hint */
1120	addr = 0;
1121	len = PAGE_ALIGN(len);
1122
1123	/* we've determined that we can make the mapping, now translate what we
1124	 * now know into VMA flags */
1125	vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
1126
 
1127	/* we're going to need to record the mapping */
1128	region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1129	if (!region)
1130		goto error_getting_region;
1131
1132	vma = vm_area_alloc(current->mm);
1133	if (!vma)
1134		goto error_getting_vma;
1135
1136	region->vm_usage = 1;
1137	region->vm_flags = vm_flags;
1138	region->vm_pgoff = pgoff;
1139
1140	vma->vm_flags = vm_flags;
1141	vma->vm_pgoff = pgoff;
1142
1143	if (file) {
1144		region->vm_file = get_file(file);
1145		vma->vm_file = get_file(file);
1146	}
1147
1148	down_write(&nommu_region_sem);
1149
1150	/* if we want to share, we need to check for regions created by other
1151	 * mmap() calls that overlap with our proposed mapping
1152	 * - we can only share with a superset match on most regular files
1153	 * - shared mappings on character devices and memory backed files are
1154	 *   permitted to overlap inexactly as far as we are concerned for in
1155	 *   these cases, sharing is handled in the driver or filesystem rather
1156	 *   than here
1157	 */
1158	if (vm_flags & VM_MAYSHARE) {
1159		struct vm_region *pregion;
1160		unsigned long pglen, rpglen, pgend, rpgend, start;
1161
1162		pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1163		pgend = pgoff + pglen;
1164
1165		for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1166			pregion = rb_entry(rb, struct vm_region, vm_rb);
1167
1168			if (!(pregion->vm_flags & VM_MAYSHARE))
1169				continue;
1170
1171			/* search for overlapping mappings on the same file */
1172			if (file_inode(pregion->vm_file) !=
1173			    file_inode(file))
1174				continue;
1175
1176			if (pregion->vm_pgoff >= pgend)
1177				continue;
1178
1179			rpglen = pregion->vm_end - pregion->vm_start;
1180			rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1181			rpgend = pregion->vm_pgoff + rpglen;
1182			if (pgoff >= rpgend)
1183				continue;
1184
1185			/* handle inexactly overlapping matches between
1186			 * mappings */
1187			if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1188			    !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1189				/* new mapping is not a subset of the region */
1190				if (!(capabilities & NOMMU_MAP_DIRECT))
1191					goto sharing_violation;
1192				continue;
1193			}
1194
1195			/* we've found a region we can share */
1196			pregion->vm_usage++;
1197			vma->vm_region = pregion;
1198			start = pregion->vm_start;
1199			start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1200			vma->vm_start = start;
1201			vma->vm_end = start + len;
1202
1203			if (pregion->vm_flags & VM_MAPPED_COPY)
1204				vma->vm_flags |= VM_MAPPED_COPY;
1205			else {
1206				ret = do_mmap_shared_file(vma);
1207				if (ret < 0) {
1208					vma->vm_region = NULL;
1209					vma->vm_start = 0;
1210					vma->vm_end = 0;
1211					pregion->vm_usage--;
1212					pregion = NULL;
1213					goto error_just_free;
1214				}
1215			}
1216			fput(region->vm_file);
1217			kmem_cache_free(vm_region_jar, region);
1218			region = pregion;
1219			result = start;
1220			goto share;
1221		}
1222
1223		/* obtain the address at which to make a shared mapping
1224		 * - this is the hook for quasi-memory character devices to
1225		 *   tell us the location of a shared mapping
1226		 */
1227		if (capabilities & NOMMU_MAP_DIRECT) {
1228			addr = file->f_op->get_unmapped_area(file, addr, len,
1229							     pgoff, flags);
1230			if (IS_ERR_VALUE(addr)) {
1231				ret = addr;
1232				if (ret != -ENOSYS)
1233					goto error_just_free;
1234
1235				/* the driver refused to tell us where to site
1236				 * the mapping so we'll have to attempt to copy
1237				 * it */
1238				ret = -ENODEV;
1239				if (!(capabilities & NOMMU_MAP_COPY))
1240					goto error_just_free;
1241
1242				capabilities &= ~NOMMU_MAP_DIRECT;
1243			} else {
1244				vma->vm_start = region->vm_start = addr;
1245				vma->vm_end = region->vm_end = addr + len;
1246			}
1247		}
1248	}
1249
1250	vma->vm_region = region;
1251
1252	/* set up the mapping
1253	 * - the region is filled in if NOMMU_MAP_DIRECT is still set
1254	 */
1255	if (file && vma->vm_flags & VM_SHARED)
1256		ret = do_mmap_shared_file(vma);
1257	else
1258		ret = do_mmap_private(vma, region, len, capabilities);
1259	if (ret < 0)
1260		goto error_just_free;
1261	add_nommu_region(region);
1262
1263	/* clear anonymous mappings that don't ask for uninitialized data */
1264	if (!vma->vm_file &&
1265	    (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) ||
1266	     !(flags & MAP_UNINITIALIZED)))
1267		memset((void *)region->vm_start, 0,
1268		       region->vm_end - region->vm_start);
1269
1270	/* okay... we have a mapping; now we have to register it */
1271	result = vma->vm_start;
1272
1273	current->mm->total_vm += len >> PAGE_SHIFT;
1274
1275share:
1276	add_vma_to_mm(current->mm, vma);
 
 
 
 
 
 
 
 
1277
1278	/* we flush the region from the icache only when the first executable
1279	 * mapping of it is made  */
1280	if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1281		flush_icache_range(region->vm_start, region->vm_end);
1282		region->vm_icache_flushed = true;
1283	}
1284
1285	up_write(&nommu_region_sem);
1286
1287	return result;
1288
1289error_just_free:
1290	up_write(&nommu_region_sem);
1291error:
 
1292	if (region->vm_file)
1293		fput(region->vm_file);
1294	kmem_cache_free(vm_region_jar, region);
1295	if (vma->vm_file)
1296		fput(vma->vm_file);
1297	vm_area_free(vma);
1298	return ret;
1299
1300sharing_violation:
1301	up_write(&nommu_region_sem);
1302	pr_warn("Attempt to share mismatched mappings\n");
1303	ret = -EINVAL;
1304	goto error;
1305
1306error_getting_vma:
1307	kmem_cache_free(vm_region_jar, region);
1308	pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1309			len, current->pid);
1310	show_free_areas(0, NULL);
1311	return -ENOMEM;
1312
1313error_getting_region:
1314	pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1315			len, current->pid);
1316	show_free_areas(0, NULL);
1317	return -ENOMEM;
1318}
1319
1320unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1321			      unsigned long prot, unsigned long flags,
1322			      unsigned long fd, unsigned long pgoff)
1323{
1324	struct file *file = NULL;
1325	unsigned long retval = -EBADF;
1326
1327	audit_mmap_fd(fd, flags);
1328	if (!(flags & MAP_ANONYMOUS)) {
1329		file = fget(fd);
1330		if (!file)
1331			goto out;
1332	}
1333
1334	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1335
1336	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1337
1338	if (file)
1339		fput(file);
1340out:
1341	return retval;
1342}
1343
1344SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1345		unsigned long, prot, unsigned long, flags,
1346		unsigned long, fd, unsigned long, pgoff)
1347{
1348	return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1349}
1350
1351#ifdef __ARCH_WANT_SYS_OLD_MMAP
1352struct mmap_arg_struct {
1353	unsigned long addr;
1354	unsigned long len;
1355	unsigned long prot;
1356	unsigned long flags;
1357	unsigned long fd;
1358	unsigned long offset;
1359};
1360
1361SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1362{
1363	struct mmap_arg_struct a;
1364
1365	if (copy_from_user(&a, arg, sizeof(a)))
1366		return -EFAULT;
1367	if (offset_in_page(a.offset))
1368		return -EINVAL;
1369
1370	return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1371			       a.offset >> PAGE_SHIFT);
1372}
1373#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1374
1375/*
1376 * split a vma into two pieces at address 'addr', a new vma is allocated either
1377 * for the first part or the tail.
1378 */
1379int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1380	      unsigned long addr, int new_below)
1381{
1382	struct vm_area_struct *new;
1383	struct vm_region *region;
1384	unsigned long npages;
 
1385
1386	/* we're only permitted to split anonymous regions (these should have
1387	 * only a single usage on the region) */
1388	if (vma->vm_file)
1389		return -ENOMEM;
1390
 
1391	if (mm->map_count >= sysctl_max_map_count)
1392		return -ENOMEM;
1393
1394	region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1395	if (!region)
1396		return -ENOMEM;
1397
1398	new = vm_area_dup(vma);
1399	if (!new) {
1400		kmem_cache_free(vm_region_jar, region);
1401		return -ENOMEM;
1402	}
1403
1404	/* most fields are the same, copy all, and then fixup */
1405	*region = *vma->vm_region;
1406	new->vm_region = region;
1407
1408	npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1409
1410	if (new_below) {
1411		region->vm_top = region->vm_end = new->vm_end = addr;
1412	} else {
1413		region->vm_start = new->vm_start = addr;
1414		region->vm_pgoff = new->vm_pgoff += npages;
1415	}
1416
 
 
 
 
 
 
 
1417	if (new->vm_ops && new->vm_ops->open)
1418		new->vm_ops->open(new);
1419
1420	delete_vma_from_mm(vma);
1421	down_write(&nommu_region_sem);
1422	delete_nommu_region(vma->vm_region);
1423	if (new_below) {
1424		vma->vm_region->vm_start = vma->vm_start = addr;
1425		vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1426	} else {
1427		vma->vm_region->vm_end = vma->vm_end = addr;
1428		vma->vm_region->vm_top = addr;
1429	}
1430	add_nommu_region(vma->vm_region);
1431	add_nommu_region(new->vm_region);
1432	up_write(&nommu_region_sem);
1433	add_vma_to_mm(mm, vma);
1434	add_vma_to_mm(mm, new);
 
 
 
1435	return 0;
 
 
 
 
 
 
1436}
1437
1438/*
1439 * shrink a VMA by removing the specified chunk from either the beginning or
1440 * the end
1441 */
1442static int shrink_vma(struct mm_struct *mm,
1443		      struct vm_area_struct *vma,
1444		      unsigned long from, unsigned long to)
1445{
1446	struct vm_region *region;
1447
1448	/* adjust the VMA's pointers, which may reposition it in the MM's tree
1449	 * and list */
1450	delete_vma_from_mm(vma);
1451	if (from > vma->vm_start)
 
1452		vma->vm_end = from;
1453	else
 
 
1454		vma->vm_start = to;
1455	add_vma_to_mm(mm, vma);
1456
1457	/* cut the backing region down to size */
1458	region = vma->vm_region;
1459	BUG_ON(region->vm_usage != 1);
1460
1461	down_write(&nommu_region_sem);
1462	delete_nommu_region(region);
1463	if (from > region->vm_start) {
1464		to = region->vm_top;
1465		region->vm_top = region->vm_end = from;
1466	} else {
1467		region->vm_start = to;
1468	}
1469	add_nommu_region(region);
1470	up_write(&nommu_region_sem);
1471
1472	free_page_series(from, to);
1473	return 0;
1474}
1475
1476/*
1477 * release a mapping
1478 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1479 *   VMA, though it need not cover the whole VMA
1480 */
1481int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
1482{
 
1483	struct vm_area_struct *vma;
1484	unsigned long end;
1485	int ret;
1486
1487	len = PAGE_ALIGN(len);
1488	if (len == 0)
1489		return -EINVAL;
1490
1491	end = start + len;
1492
1493	/* find the first potentially overlapping VMA */
1494	vma = find_vma(mm, start);
1495	if (!vma) {
1496		static int limit;
1497		if (limit < 5) {
1498			pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1499					current->pid, current->comm,
1500					start, start + len - 1);
1501			limit++;
1502		}
1503		return -EINVAL;
1504	}
1505
1506	/* we're allowed to split an anonymous VMA but not a file-backed one */
1507	if (vma->vm_file) {
1508		do {
1509			if (start > vma->vm_start)
1510				return -EINVAL;
1511			if (end == vma->vm_end)
1512				goto erase_whole_vma;
1513			vma = vma->vm_next;
1514		} while (vma);
1515		return -EINVAL;
1516	} else {
1517		/* the chunk must be a subset of the VMA found */
1518		if (start == vma->vm_start && end == vma->vm_end)
1519			goto erase_whole_vma;
1520		if (start < vma->vm_start || end > vma->vm_end)
1521			return -EINVAL;
1522		if (offset_in_page(start))
1523			return -EINVAL;
1524		if (end != vma->vm_end && offset_in_page(end))
1525			return -EINVAL;
1526		if (start != vma->vm_start && end != vma->vm_end) {
1527			ret = split_vma(mm, vma, start, 1);
1528			if (ret < 0)
1529				return ret;
1530		}
1531		return shrink_vma(mm, vma, start, end);
1532	}
1533
1534erase_whole_vma:
1535	delete_vma_from_mm(vma);
1536	delete_vma(mm, vma);
1537	return 0;
 
 
1538}
1539EXPORT_SYMBOL(do_munmap);
1540
1541int vm_munmap(unsigned long addr, size_t len)
1542{
1543	struct mm_struct *mm = current->mm;
1544	int ret;
1545
1546	down_write(&mm->mmap_sem);
1547	ret = do_munmap(mm, addr, len, NULL);
1548	up_write(&mm->mmap_sem);
1549	return ret;
1550}
1551EXPORT_SYMBOL(vm_munmap);
1552
1553SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1554{
1555	return vm_munmap(addr, len);
1556}
1557
1558/*
1559 * release all the mappings made in a process's VM space
1560 */
1561void exit_mmap(struct mm_struct *mm)
1562{
 
1563	struct vm_area_struct *vma;
1564
1565	if (!mm)
1566		return;
1567
1568	mm->total_vm = 0;
1569
1570	while ((vma = mm->mmap)) {
1571		mm->mmap = vma->vm_next;
1572		delete_vma_from_mm(vma);
 
 
 
 
1573		delete_vma(mm, vma);
1574		cond_resched();
1575	}
1576}
1577
1578int vm_brk(unsigned long addr, unsigned long len)
1579{
1580	return -ENOMEM;
1581}
1582
1583/*
1584 * expand (or shrink) an existing mapping, potentially moving it at the same
1585 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1586 *
1587 * under NOMMU conditions, we only permit changing a mapping's size, and only
1588 * as long as it stays within the region allocated by do_mmap_private() and the
1589 * block is not shareable
1590 *
1591 * MREMAP_FIXED is not supported under NOMMU conditions
1592 */
1593static unsigned long do_mremap(unsigned long addr,
1594			unsigned long old_len, unsigned long new_len,
1595			unsigned long flags, unsigned long new_addr)
1596{
1597	struct vm_area_struct *vma;
1598
1599	/* insanity checks first */
1600	old_len = PAGE_ALIGN(old_len);
1601	new_len = PAGE_ALIGN(new_len);
1602	if (old_len == 0 || new_len == 0)
1603		return (unsigned long) -EINVAL;
1604
1605	if (offset_in_page(addr))
1606		return -EINVAL;
1607
1608	if (flags & MREMAP_FIXED && new_addr != addr)
1609		return (unsigned long) -EINVAL;
1610
1611	vma = find_vma_exact(current->mm, addr, old_len);
1612	if (!vma)
1613		return (unsigned long) -EINVAL;
1614
1615	if (vma->vm_end != vma->vm_start + old_len)
1616		return (unsigned long) -EFAULT;
1617
1618	if (vma->vm_flags & VM_MAYSHARE)
1619		return (unsigned long) -EPERM;
1620
1621	if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1622		return (unsigned long) -ENOMEM;
1623
1624	/* all checks complete - do it */
1625	vma->vm_end = vma->vm_start + new_len;
1626	return vma->vm_start;
1627}
1628
1629SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1630		unsigned long, new_len, unsigned long, flags,
1631		unsigned long, new_addr)
1632{
1633	unsigned long ret;
1634
1635	down_write(&current->mm->mmap_sem);
1636	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1637	up_write(&current->mm->mmap_sem);
1638	return ret;
1639}
1640
1641struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1642			 unsigned int foll_flags)
1643{
1644	return NULL;
1645}
1646
1647int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1648		unsigned long pfn, unsigned long size, pgprot_t prot)
1649{
1650	if (addr != (pfn << PAGE_SHIFT))
1651		return -EINVAL;
1652
1653	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1654	return 0;
1655}
1656EXPORT_SYMBOL(remap_pfn_range);
1657
1658int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1659{
1660	unsigned long pfn = start >> PAGE_SHIFT;
1661	unsigned long vm_len = vma->vm_end - vma->vm_start;
1662
1663	pfn += vma->vm_pgoff;
1664	return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1665}
1666EXPORT_SYMBOL(vm_iomap_memory);
1667
1668int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1669			unsigned long pgoff)
1670{
1671	unsigned int size = vma->vm_end - vma->vm_start;
1672
1673	if (!(vma->vm_flags & VM_USERMAP))
1674		return -EINVAL;
1675
1676	vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1677	vma->vm_end = vma->vm_start + size;
1678
1679	return 0;
1680}
1681EXPORT_SYMBOL(remap_vmalloc_range);
1682
1683unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1684	unsigned long len, unsigned long pgoff, unsigned long flags)
1685{
1686	return -ENOMEM;
1687}
1688
1689vm_fault_t filemap_fault(struct vm_fault *vmf)
1690{
1691	BUG();
1692	return 0;
1693}
1694EXPORT_SYMBOL(filemap_fault);
1695
1696void filemap_map_pages(struct vm_fault *vmf,
1697		pgoff_t start_pgoff, pgoff_t end_pgoff)
1698{
1699	BUG();
 
1700}
1701EXPORT_SYMBOL(filemap_map_pages);
1702
1703int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1704		unsigned long addr, void *buf, int len, unsigned int gup_flags)
1705{
1706	struct vm_area_struct *vma;
1707	int write = gup_flags & FOLL_WRITE;
1708
1709	if (down_read_killable(&mm->mmap_sem))
1710		return 0;
1711
1712	/* the access must start within one of the target process's mappings */
1713	vma = find_vma(mm, addr);
1714	if (vma) {
1715		/* don't overrun this mapping */
1716		if (addr + len >= vma->vm_end)
1717			len = vma->vm_end - addr;
1718
1719		/* only read or write mappings where it is permitted */
1720		if (write && vma->vm_flags & VM_MAYWRITE)
1721			copy_to_user_page(vma, NULL, addr,
1722					 (void *) addr, buf, len);
1723		else if (!write && vma->vm_flags & VM_MAYREAD)
1724			copy_from_user_page(vma, NULL, addr,
1725					    buf, (void *) addr, len);
1726		else
1727			len = 0;
1728	} else {
1729		len = 0;
1730	}
1731
1732	up_read(&mm->mmap_sem);
1733
1734	return len;
1735}
1736
1737/**
1738 * access_remote_vm - access another process' address space
1739 * @mm:		the mm_struct of the target address space
1740 * @addr:	start address to access
1741 * @buf:	source or destination buffer
1742 * @len:	number of bytes to transfer
1743 * @gup_flags:	flags modifying lookup behaviour
1744 *
1745 * The caller must hold a reference on @mm.
1746 */
1747int access_remote_vm(struct mm_struct *mm, unsigned long addr,
1748		void *buf, int len, unsigned int gup_flags)
1749{
1750	return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
1751}
1752
1753/*
1754 * Access another process' address space.
1755 * - source/target buffer must be kernel space
1756 */
1757int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
1758		unsigned int gup_flags)
1759{
1760	struct mm_struct *mm;
1761
1762	if (addr + len < addr)
1763		return 0;
1764
1765	mm = get_task_mm(tsk);
1766	if (!mm)
1767		return 0;
1768
1769	len = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
1770
1771	mmput(mm);
1772	return len;
1773}
1774EXPORT_SYMBOL_GPL(access_process_vm);
1775
1776/**
1777 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1778 * @inode: The inode to check
1779 * @size: The current filesize of the inode
1780 * @newsize: The proposed filesize of the inode
1781 *
1782 * Check the shared mappings on an inode on behalf of a shrinking truncate to
1783 * make sure that that any outstanding VMAs aren't broken and then shrink the
1784 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
1785 * automatically grant mappings that are too large.
1786 */
1787int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
1788				size_t newsize)
1789{
1790	struct vm_area_struct *vma;
1791	struct vm_region *region;
1792	pgoff_t low, high;
1793	size_t r_size, r_top;
1794
1795	low = newsize >> PAGE_SHIFT;
1796	high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1797
1798	down_write(&nommu_region_sem);
1799	i_mmap_lock_read(inode->i_mapping);
1800
1801	/* search for VMAs that fall within the dead zone */
1802	vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
1803		/* found one - only interested if it's shared out of the page
1804		 * cache */
1805		if (vma->vm_flags & VM_SHARED) {
1806			i_mmap_unlock_read(inode->i_mapping);
1807			up_write(&nommu_region_sem);
1808			return -ETXTBSY; /* not quite true, but near enough */
1809		}
1810	}
1811
1812	/* reduce any regions that overlap the dead zone - if in existence,
1813	 * these will be pointed to by VMAs that don't overlap the dead zone
1814	 *
1815	 * we don't check for any regions that start beyond the EOF as there
1816	 * shouldn't be any
1817	 */
1818	vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
1819		if (!(vma->vm_flags & VM_SHARED))
1820			continue;
1821
1822		region = vma->vm_region;
1823		r_size = region->vm_top - region->vm_start;
1824		r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
1825
1826		if (r_top > newsize) {
1827			region->vm_top -= r_top - newsize;
1828			if (region->vm_end > region->vm_top)
1829				region->vm_end = region->vm_top;
1830		}
1831	}
1832
1833	i_mmap_unlock_read(inode->i_mapping);
1834	up_write(&nommu_region_sem);
1835	return 0;
1836}
1837
1838/*
1839 * Initialise sysctl_user_reserve_kbytes.
1840 *
1841 * This is intended to prevent a user from starting a single memory hogging
1842 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1843 * mode.
1844 *
1845 * The default value is min(3% of free memory, 128MB)
1846 * 128MB is enough to recover with sshd/login, bash, and top/kill.
1847 */
1848static int __meminit init_user_reserve(void)
1849{
1850	unsigned long free_kbytes;
1851
1852	free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
1853
1854	sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
1855	return 0;
1856}
1857subsys_initcall(init_user_reserve);
1858
1859/*
1860 * Initialise sysctl_admin_reserve_kbytes.
1861 *
1862 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1863 * to log in and kill a memory hogging process.
1864 *
1865 * Systems with more than 256MB will reserve 8MB, enough to recover
1866 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1867 * only reserve 3% of free pages by default.
1868 */
1869static int __meminit init_admin_reserve(void)
1870{
1871	unsigned long free_kbytes;
1872
1873	free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
1874
1875	sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
1876	return 0;
1877}
1878subsys_initcall(init_admin_reserve);