2 #include <linux/slab.h>
3 #include <linux/string.h>
4 #include <linux/compiler.h>
5 #include <linux/export.h>
7 #include <linux/sched.h>
8 #include <linux/sched/mm.h>
9 #include <linux/security.h>
10 #include <linux/swap.h>
11 #include <linux/swapops.h>
12 #include <linux/mman.h>
13 #include <linux/hugetlb.h>
14 #include <linux/vmalloc.h>
15 #include <linux/userfaultfd_k.h>
17 #include <asm/sections.h>
18 #include <linux/uaccess.h>
22 static inline int is_kernel_rodata(unsigned long addr)
24 return addr >= (unsigned long)__start_rodata &&
25 addr < (unsigned long)__end_rodata;
29 * kfree_const - conditionally free memory
30 * @x: pointer to the memory
32 * Function calls kfree only if @x is not in .rodata section.
34 void kfree_const(const void *x)
36 if (!is_kernel_rodata((unsigned long)x))
39 EXPORT_SYMBOL(kfree_const);
42 * kstrdup - allocate space for and copy an existing string
43 * @s: the string to duplicate
44 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
46 char *kstrdup(const char *s, gfp_t gfp)
55 buf = kmalloc_track_caller(len, gfp);
60 EXPORT_SYMBOL(kstrdup);
63 * kstrdup_const - conditionally duplicate an existing const string
64 * @s: the string to duplicate
65 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
67 * Function returns source string if it is in .rodata section otherwise it
68 * fallbacks to kstrdup.
69 * Strings allocated by kstrdup_const should be freed by kfree_const.
71 const char *kstrdup_const(const char *s, gfp_t gfp)
73 if (is_kernel_rodata((unsigned long)s))
76 return kstrdup(s, gfp);
78 EXPORT_SYMBOL(kstrdup_const);
81 * kstrndup - allocate space for and copy an existing string
82 * @s: the string to duplicate
83 * @max: read at most @max chars from @s
84 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
86 char *kstrndup(const char *s, size_t max, gfp_t gfp)
94 len = strnlen(s, max);
95 buf = kmalloc_track_caller(len+1, gfp);
102 EXPORT_SYMBOL(kstrndup);
105 * kmemdup - duplicate region of memory
107 * @src: memory region to duplicate
108 * @len: memory region length
109 * @gfp: GFP mask to use
111 void *kmemdup(const void *src, size_t len, gfp_t gfp)
115 p = kmalloc_track_caller(len, gfp);
120 EXPORT_SYMBOL(kmemdup);
123 * memdup_user - duplicate memory region from user space
125 * @src: source address in user space
126 * @len: number of bytes to copy
128 * Returns an ERR_PTR() on failure.
130 void *memdup_user(const void __user *src, size_t len)
135 * Always use GFP_KERNEL, since copy_from_user() can sleep and
136 * cause pagefault, which makes it pointless to use GFP_NOFS
139 p = kmalloc_track_caller(len, GFP_KERNEL);
141 return ERR_PTR(-ENOMEM);
143 if (copy_from_user(p, src, len)) {
145 return ERR_PTR(-EFAULT);
150 EXPORT_SYMBOL(memdup_user);
153 * strndup_user - duplicate an existing string from user space
154 * @s: The string to duplicate
155 * @n: Maximum number of bytes to copy, including the trailing NUL.
157 char *strndup_user(const char __user *s, long n)
162 length = strnlen_user(s, n);
165 return ERR_PTR(-EFAULT);
168 return ERR_PTR(-EINVAL);
170 p = memdup_user(s, length);
175 p[length - 1] = '\0';
179 EXPORT_SYMBOL(strndup_user);
182 * memdup_user_nul - duplicate memory region from user space and NUL-terminate
184 * @src: source address in user space
185 * @len: number of bytes to copy
187 * Returns an ERR_PTR() on failure.
189 void *memdup_user_nul(const void __user *src, size_t len)
194 * Always use GFP_KERNEL, since copy_from_user() can sleep and
195 * cause pagefault, which makes it pointless to use GFP_NOFS
198 p = kmalloc_track_caller(len + 1, GFP_KERNEL);
200 return ERR_PTR(-ENOMEM);
202 if (copy_from_user(p, src, len)) {
204 return ERR_PTR(-EFAULT);
210 EXPORT_SYMBOL(memdup_user_nul);
212 void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
213 struct vm_area_struct *prev, struct rb_node *rb_parent)
215 struct vm_area_struct *next;
219 next = prev->vm_next;
224 next = rb_entry(rb_parent,
225 struct vm_area_struct, vm_rb);
234 /* Check if the vma is being used as a stack by this task */
235 int vma_is_stack_for_current(struct vm_area_struct *vma)
237 struct task_struct * __maybe_unused t = current;
239 return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
242 #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
243 void arch_pick_mmap_layout(struct mm_struct *mm)
245 mm->mmap_base = TASK_UNMAPPED_BASE;
246 mm->get_unmapped_area = arch_get_unmapped_area;
251 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
252 * back to the regular GUP.
253 * If the architecture not support this function, simply return with no
256 int __weak __get_user_pages_fast(unsigned long start,
257 int nr_pages, int write, struct page **pages)
261 EXPORT_SYMBOL_GPL(__get_user_pages_fast);
264 * get_user_pages_fast() - pin user pages in memory
265 * @start: starting user address
266 * @nr_pages: number of pages from start to pin
267 * @write: whether pages will be written to
268 * @pages: array that receives pointers to the pages pinned.
269 * Should be at least nr_pages long.
271 * Returns number of pages pinned. This may be fewer than the number
272 * requested. If nr_pages is 0 or negative, returns 0. If no pages
273 * were pinned, returns -errno.
275 * get_user_pages_fast provides equivalent functionality to get_user_pages,
276 * operating on current and current->mm, with force=0 and vma=NULL. However
277 * unlike get_user_pages, it must be called without mmap_sem held.
279 * get_user_pages_fast may take mmap_sem and page table locks, so no
280 * assumptions can be made about lack of locking. get_user_pages_fast is to be
281 * implemented in a way that is advantageous (vs get_user_pages()) when the
282 * user memory area is already faulted in and present in ptes. However if the
283 * pages have to be faulted in, it may turn out to be slightly slower so
284 * callers need to carefully consider what to use. On many architectures,
285 * get_user_pages_fast simply falls back to get_user_pages.
287 int __weak get_user_pages_fast(unsigned long start,
288 int nr_pages, int write, struct page **pages)
290 return get_user_pages_unlocked(start, nr_pages, pages,
291 write ? FOLL_WRITE : 0);
293 EXPORT_SYMBOL_GPL(get_user_pages_fast);
295 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
296 unsigned long len, unsigned long prot,
297 unsigned long flag, unsigned long pgoff)
300 struct mm_struct *mm = current->mm;
301 unsigned long populate;
304 ret = security_mmap_file(file, prot, flag);
306 if (down_write_killable(&mm->mmap_sem))
308 ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
310 up_write(&mm->mmap_sem);
311 userfaultfd_unmap_complete(mm, &uf);
313 mm_populate(ret, populate);
318 unsigned long vm_mmap(struct file *file, unsigned long addr,
319 unsigned long len, unsigned long prot,
320 unsigned long flag, unsigned long offset)
322 if (unlikely(offset + PAGE_ALIGN(len) < offset))
324 if (unlikely(offset_in_page(offset)))
327 return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
329 EXPORT_SYMBOL(vm_mmap);
331 void kvfree(const void *addr)
333 if (is_vmalloc_addr(addr))
338 EXPORT_SYMBOL(kvfree);
340 static inline void *__page_rmapping(struct page *page)
342 unsigned long mapping;
344 mapping = (unsigned long)page->mapping;
345 mapping &= ~PAGE_MAPPING_FLAGS;
347 return (void *)mapping;
350 /* Neutral page->mapping pointer to address_space or anon_vma or other */
351 void *page_rmapping(struct page *page)
353 page = compound_head(page);
354 return __page_rmapping(page);
358 * Return true if this page is mapped into pagetables.
359 * For compound page it returns true if any subpage of compound page is mapped.
361 bool page_mapped(struct page *page)
365 if (likely(!PageCompound(page)))
366 return atomic_read(&page->_mapcount) >= 0;
367 page = compound_head(page);
368 if (atomic_read(compound_mapcount_ptr(page)) >= 0)
372 for (i = 0; i < hpage_nr_pages(page); i++) {
373 if (atomic_read(&page[i]._mapcount) >= 0)
378 EXPORT_SYMBOL(page_mapped);
380 struct anon_vma *page_anon_vma(struct page *page)
382 unsigned long mapping;
384 page = compound_head(page);
385 mapping = (unsigned long)page->mapping;
386 if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
388 return __page_rmapping(page);
391 struct address_space *page_mapping(struct page *page)
393 struct address_space *mapping;
395 page = compound_head(page);
397 /* This happens if someone calls flush_dcache_page on slab page */
398 if (unlikely(PageSlab(page)))
401 if (unlikely(PageSwapCache(page))) {
404 entry.val = page_private(page);
405 return swap_address_space(entry);
408 mapping = page->mapping;
409 if ((unsigned long)mapping & PAGE_MAPPING_ANON)
412 return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS);
414 EXPORT_SYMBOL(page_mapping);
416 /* Slow path of page_mapcount() for compound pages */
417 int __page_mapcount(struct page *page)
421 ret = atomic_read(&page->_mapcount) + 1;
423 * For file THP page->_mapcount contains total number of mapping
424 * of the page: no need to look into compound_mapcount.
426 if (!PageAnon(page) && !PageHuge(page))
428 page = compound_head(page);
429 ret += atomic_read(compound_mapcount_ptr(page)) + 1;
430 if (PageDoubleMap(page))
434 EXPORT_SYMBOL_GPL(__page_mapcount);
436 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
437 int sysctl_overcommit_ratio __read_mostly = 50;
438 unsigned long sysctl_overcommit_kbytes __read_mostly;
439 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
440 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
441 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
443 int overcommit_ratio_handler(struct ctl_table *table, int write,
444 void __user *buffer, size_t *lenp,
449 ret = proc_dointvec(table, write, buffer, lenp, ppos);
450 if (ret == 0 && write)
451 sysctl_overcommit_kbytes = 0;
455 int overcommit_kbytes_handler(struct ctl_table *table, int write,
456 void __user *buffer, size_t *lenp,
461 ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
462 if (ret == 0 && write)
463 sysctl_overcommit_ratio = 0;
468 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
470 unsigned long vm_commit_limit(void)
472 unsigned long allowed;
474 if (sysctl_overcommit_kbytes)
475 allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
477 allowed = ((totalram_pages - hugetlb_total_pages())
478 * sysctl_overcommit_ratio / 100);
479 allowed += total_swap_pages;
485 * Make sure vm_committed_as in one cacheline and not cacheline shared with
486 * other variables. It can be updated by several CPUs frequently.
488 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
491 * The global memory commitment made in the system can be a metric
492 * that can be used to drive ballooning decisions when Linux is hosted
493 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
494 * balancing memory across competing virtual machines that are hosted.
495 * Several metrics drive this policy engine including the guest reported
498 unsigned long vm_memory_committed(void)
500 return percpu_counter_read_positive(&vm_committed_as);
502 EXPORT_SYMBOL_GPL(vm_memory_committed);
505 * Check that a process has enough memory to allocate a new virtual
506 * mapping. 0 means there is enough memory for the allocation to
507 * succeed and -ENOMEM implies there is not.
509 * We currently support three overcommit policies, which are set via the
510 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
512 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
513 * Additional code 2002 Jul 20 by Robert Love.
515 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
517 * Note this is a helper function intended to be used by LSMs which
518 * wish to use this logic.
520 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
522 long free, allowed, reserve;
524 VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
525 -(s64)vm_committed_as_batch * num_online_cpus(),
526 "memory commitment underflow");
528 vm_acct_memory(pages);
531 * Sometimes we want to use more memory than we have
533 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
536 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
537 free = global_page_state(NR_FREE_PAGES);
538 free += global_node_page_state(NR_FILE_PAGES);
541 * shmem pages shouldn't be counted as free in this
542 * case, they can't be purged, only swapped out, and
543 * that won't affect the overall amount of available
544 * memory in the system.
546 free -= global_node_page_state(NR_SHMEM);
548 free += get_nr_swap_pages();
551 * Any slabs which are created with the
552 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
553 * which are reclaimable, under pressure. The dentry
554 * cache and most inode caches should fall into this
556 free += global_page_state(NR_SLAB_RECLAIMABLE);
559 * Leave reserved pages. The pages are not for anonymous pages.
561 if (free <= totalreserve_pages)
564 free -= totalreserve_pages;
567 * Reserve some for root
570 free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
578 allowed = vm_commit_limit();
580 * Reserve some for root
583 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
586 * Don't let a single process grow so big a user can't recover
589 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
590 allowed -= min_t(long, mm->total_vm / 32, reserve);
593 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
596 vm_unacct_memory(pages);
602 * get_cmdline() - copy the cmdline value to a buffer.
603 * @task: the task whose cmdline value to copy.
604 * @buffer: the buffer to copy to.
605 * @buflen: the length of the buffer. Larger cmdline values are truncated
607 * Returns the size of the cmdline field copied. Note that the copy does
608 * not guarantee an ending NULL byte.
610 int get_cmdline(struct task_struct *task, char *buffer, int buflen)
614 struct mm_struct *mm = get_task_mm(task);
615 unsigned long arg_start, arg_end, env_start, env_end;
619 goto out_mm; /* Shh! No looking before we're done */
621 down_read(&mm->mmap_sem);
622 arg_start = mm->arg_start;
623 arg_end = mm->arg_end;
624 env_start = mm->env_start;
625 env_end = mm->env_end;
626 up_read(&mm->mmap_sem);
628 len = arg_end - arg_start;
633 res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
636 * If the nul at the end of args has been overwritten, then
637 * assume application is using setproctitle(3).
639 if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
640 len = strnlen(buffer, res);
644 len = env_end - env_start;
645 if (len > buflen - res)
647 res += access_process_vm(task, env_start,
650 res = strnlen(buffer, res);