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