Linux Audio

Check our new training course

Loading...
v4.6
  1#include <linux/mm.h>
  2#include <linux/slab.h>
  3#include <linux/string.h>
  4#include <linux/compiler.h>
  5#include <linux/export.h>
  6#include <linux/err.h>
  7#include <linux/sched.h>
 
 
  8#include <linux/security.h>
  9#include <linux/swap.h>
 10#include <linux/swapops.h>
 11#include <linux/mman.h>
 12#include <linux/hugetlb.h>
 13#include <linux/vmalloc.h>
 
 14
 15#include <asm/sections.h>
 16#include <asm/uaccess.h>
 17
 18#include "internal.h"
 19
 20static inline int is_kernel_rodata(unsigned long addr)
 21{
 22	return addr >= (unsigned long)__start_rodata &&
 23		addr < (unsigned long)__end_rodata;
 24}
 25
 26/**
 27 * kfree_const - conditionally free memory
 28 * @x: pointer to the memory
 29 *
 30 * Function calls kfree only if @x is not in .rodata section.
 31 */
 32void kfree_const(const void *x)
 33{
 34	if (!is_kernel_rodata((unsigned long)x))
 35		kfree(x);
 36}
 37EXPORT_SYMBOL(kfree_const);
 38
 39/**
 40 * kstrdup - allocate space for and copy an existing string
 41 * @s: the string to duplicate
 42 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 43 */
 44char *kstrdup(const char *s, gfp_t gfp)
 45{
 46	size_t len;
 47	char *buf;
 48
 49	if (!s)
 50		return NULL;
 51
 52	len = strlen(s) + 1;
 53	buf = kmalloc_track_caller(len, gfp);
 54	if (buf)
 55		memcpy(buf, s, len);
 56	return buf;
 57}
 58EXPORT_SYMBOL(kstrdup);
 59
 60/**
 61 * kstrdup_const - conditionally duplicate an existing const string
 62 * @s: the string to duplicate
 63 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 64 *
 65 * Function returns source string if it is in .rodata section otherwise it
 66 * fallbacks to kstrdup.
 67 * Strings allocated by kstrdup_const should be freed by kfree_const.
 68 */
 69const char *kstrdup_const(const char *s, gfp_t gfp)
 70{
 71	if (is_kernel_rodata((unsigned long)s))
 72		return s;
 73
 74	return kstrdup(s, gfp);
 75}
 76EXPORT_SYMBOL(kstrdup_const);
 77
 78/**
 79 * kstrndup - allocate space for and copy an existing string
 80 * @s: the string to duplicate
 81 * @max: read at most @max chars from @s
 82 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 
 
 83 */
 84char *kstrndup(const char *s, size_t max, gfp_t gfp)
 85{
 86	size_t len;
 87	char *buf;
 88
 89	if (!s)
 90		return NULL;
 91
 92	len = strnlen(s, max);
 93	buf = kmalloc_track_caller(len+1, gfp);
 94	if (buf) {
 95		memcpy(buf, s, len);
 96		buf[len] = '\0';
 97	}
 98	return buf;
 99}
100EXPORT_SYMBOL(kstrndup);
101
102/**
103 * kmemdup - duplicate region of memory
104 *
105 * @src: memory region to duplicate
106 * @len: memory region length
107 * @gfp: GFP mask to use
108 */
109void *kmemdup(const void *src, size_t len, gfp_t gfp)
110{
111	void *p;
112
113	p = kmalloc_track_caller(len, gfp);
114	if (p)
115		memcpy(p, src, len);
116	return p;
117}
118EXPORT_SYMBOL(kmemdup);
119
120/**
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
121 * memdup_user - duplicate memory region from user space
122 *
123 * @src: source address in user space
124 * @len: number of bytes to copy
125 *
126 * Returns an ERR_PTR() on failure.
 
127 */
128void *memdup_user(const void __user *src, size_t len)
129{
130	void *p;
131
132	/*
133	 * Always use GFP_KERNEL, since copy_from_user() can sleep and
134	 * cause pagefault, which makes it pointless to use GFP_NOFS
135	 * or GFP_ATOMIC.
136	 */
137	p = kmalloc_track_caller(len, GFP_KERNEL);
138	if (!p)
139		return ERR_PTR(-ENOMEM);
140
141	if (copy_from_user(p, src, len)) {
142		kfree(p);
143		return ERR_PTR(-EFAULT);
144	}
145
146	return p;
147}
148EXPORT_SYMBOL(memdup_user);
149
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
150/*
151 * strndup_user - duplicate an existing string from user space
152 * @s: The string to duplicate
153 * @n: Maximum number of bytes to copy, including the trailing NUL.
154 */
155char *strndup_user(const char __user *s, long n)
156{
157	char *p;
158	long length;
159
160	length = strnlen_user(s, n);
161
162	if (!length)
163		return ERR_PTR(-EFAULT);
164
165	if (length > n)
166		return ERR_PTR(-EINVAL);
167
168	p = memdup_user(s, length);
169
170	if (IS_ERR(p))
171		return p;
172
173	p[length - 1] = '\0';
174
175	return p;
176}
177EXPORT_SYMBOL(strndup_user);
178
179/**
180 * memdup_user_nul - duplicate memory region from user space and NUL-terminate
181 *
182 * @src: source address in user space
183 * @len: number of bytes to copy
184 *
185 * Returns an ERR_PTR() on failure.
186 */
187void *memdup_user_nul(const void __user *src, size_t len)
188{
189	char *p;
190
191	/*
192	 * Always use GFP_KERNEL, since copy_from_user() can sleep and
193	 * cause pagefault, which makes it pointless to use GFP_NOFS
194	 * or GFP_ATOMIC.
195	 */
196	p = kmalloc_track_caller(len + 1, GFP_KERNEL);
197	if (!p)
198		return ERR_PTR(-ENOMEM);
199
200	if (copy_from_user(p, src, len)) {
201		kfree(p);
202		return ERR_PTR(-EFAULT);
203	}
204	p[len] = '\0';
205
206	return p;
207}
208EXPORT_SYMBOL(memdup_user_nul);
209
210void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
211		struct vm_area_struct *prev, struct rb_node *rb_parent)
212{
213	struct vm_area_struct *next;
214
215	vma->vm_prev = prev;
216	if (prev) {
217		next = prev->vm_next;
218		prev->vm_next = vma;
219	} else {
220		mm->mmap = vma;
221		if (rb_parent)
222			next = rb_entry(rb_parent,
223					struct vm_area_struct, vm_rb);
224		else
225			next = NULL;
226	}
227	vma->vm_next = next;
228	if (next)
229		next->vm_prev = vma;
230}
231
232/* Check if the vma is being used as a stack by this task */
233int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t)
234{
 
 
235	return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
236}
237
238#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
239void arch_pick_mmap_layout(struct mm_struct *mm)
240{
241	mm->mmap_base = TASK_UNMAPPED_BASE;
242	mm->get_unmapped_area = arch_get_unmapped_area;
243}
244#endif
245
246/*
247 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
248 * back to the regular GUP.
249 * If the architecture not support this function, simply return with no
250 * page pinned
 
 
251 */
252int __weak __get_user_pages_fast(unsigned long start,
253				 int nr_pages, int write, struct page **pages)
254{
255	return 0;
256}
257EXPORT_SYMBOL_GPL(__get_user_pages_fast);
258
259/**
260 * get_user_pages_fast() - pin user pages in memory
261 * @start:	starting user address
262 * @nr_pages:	number of pages from start to pin
263 * @write:	whether pages will be written to
264 * @pages:	array that receives pointers to the pages pinned.
265 *		Should be at least nr_pages long.
266 *
267 * Returns number of pages pinned. This may be fewer than the number
268 * requested. If nr_pages is 0 or negative, returns 0. If no pages
269 * were pinned, returns -errno.
270 *
271 * get_user_pages_fast provides equivalent functionality to get_user_pages,
272 * operating on current and current->mm, with force=0 and vma=NULL. However
273 * unlike get_user_pages, it must be called without mmap_sem held.
274 *
275 * get_user_pages_fast may take mmap_sem and page table locks, so no
276 * assumptions can be made about lack of locking. get_user_pages_fast is to be
277 * implemented in a way that is advantageous (vs get_user_pages()) when the
278 * user memory area is already faulted in and present in ptes. However if the
279 * pages have to be faulted in, it may turn out to be slightly slower so
280 * callers need to carefully consider what to use. On many architectures,
281 * get_user_pages_fast simply falls back to get_user_pages.
282 */
283int __weak get_user_pages_fast(unsigned long start,
284				int nr_pages, int write, struct page **pages)
285{
286	return get_user_pages_unlocked(start, nr_pages, write, 0, pages);
 
287}
288EXPORT_SYMBOL_GPL(get_user_pages_fast);
289
290unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
291	unsigned long len, unsigned long prot,
292	unsigned long flag, unsigned long pgoff)
293{
294	unsigned long ret;
295	struct mm_struct *mm = current->mm;
296	unsigned long populate;
 
297
298	ret = security_mmap_file(file, prot, flag);
299	if (!ret) {
300		down_write(&mm->mmap_sem);
 
301		ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
302				    &populate);
303		up_write(&mm->mmap_sem);
 
304		if (populate)
305			mm_populate(ret, populate);
306	}
307	return ret;
308}
309
310unsigned long vm_mmap(struct file *file, unsigned long addr,
311	unsigned long len, unsigned long prot,
312	unsigned long flag, unsigned long offset)
313{
314	if (unlikely(offset + PAGE_ALIGN(len) < offset))
315		return -EINVAL;
316	if (unlikely(offset_in_page(offset)))
317		return -EINVAL;
318
319	return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
320}
321EXPORT_SYMBOL(vm_mmap);
322
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
323void kvfree(const void *addr)
324{
325	if (is_vmalloc_addr(addr))
326		vfree(addr);
327	else
328		kfree(addr);
329}
330EXPORT_SYMBOL(kvfree);
331
332static inline void *__page_rmapping(struct page *page)
333{
334	unsigned long mapping;
335
336	mapping = (unsigned long)page->mapping;
337	mapping &= ~PAGE_MAPPING_FLAGS;
338
339	return (void *)mapping;
340}
341
342/* Neutral page->mapping pointer to address_space or anon_vma or other */
343void *page_rmapping(struct page *page)
344{
345	page = compound_head(page);
346	return __page_rmapping(page);
347}
348
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
349struct anon_vma *page_anon_vma(struct page *page)
350{
351	unsigned long mapping;
352
353	page = compound_head(page);
354	mapping = (unsigned long)page->mapping;
355	if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
356		return NULL;
357	return __page_rmapping(page);
358}
359
360struct address_space *page_mapping(struct page *page)
361{
362	struct address_space *mapping;
363
364	page = compound_head(page);
365
366	/* This happens if someone calls flush_dcache_page on slab page */
367	if (unlikely(PageSlab(page)))
368		return NULL;
369
370	if (unlikely(PageSwapCache(page))) {
371		swp_entry_t entry;
372
373		entry.val = page_private(page);
374		return swap_address_space(entry);
375	}
376
377	mapping = page->mapping;
378	if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
379		return NULL;
380	return mapping;
 
 
 
 
 
 
 
 
 
 
 
 
381}
382
383/* Slow path of page_mapcount() for compound pages */
384int __page_mapcount(struct page *page)
385{
386	int ret;
387
388	ret = atomic_read(&page->_mapcount) + 1;
 
 
 
 
 
 
389	page = compound_head(page);
390	ret += atomic_read(compound_mapcount_ptr(page)) + 1;
391	if (PageDoubleMap(page))
392		ret--;
393	return ret;
394}
395EXPORT_SYMBOL_GPL(__page_mapcount);
396
397int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
398int sysctl_overcommit_ratio __read_mostly = 50;
399unsigned long sysctl_overcommit_kbytes __read_mostly;
400int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
401unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
402unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
403
404int overcommit_ratio_handler(struct ctl_table *table, int write,
405			     void __user *buffer, size_t *lenp,
406			     loff_t *ppos)
407{
408	int ret;
409
410	ret = proc_dointvec(table, write, buffer, lenp, ppos);
411	if (ret == 0 && write)
412		sysctl_overcommit_kbytes = 0;
413	return ret;
414}
415
416int overcommit_kbytes_handler(struct ctl_table *table, int write,
417			     void __user *buffer, size_t *lenp,
418			     loff_t *ppos)
419{
420	int ret;
421
422	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
423	if (ret == 0 && write)
424		sysctl_overcommit_ratio = 0;
425	return ret;
426}
427
428/*
429 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
430 */
431unsigned long vm_commit_limit(void)
432{
433	unsigned long allowed;
434
435	if (sysctl_overcommit_kbytes)
436		allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
437	else
438		allowed = ((totalram_pages - hugetlb_total_pages())
439			   * sysctl_overcommit_ratio / 100);
440	allowed += total_swap_pages;
441
442	return allowed;
443}
444
445/*
446 * Make sure vm_committed_as in one cacheline and not cacheline shared with
447 * other variables. It can be updated by several CPUs frequently.
448 */
449struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
450
451/*
452 * The global memory commitment made in the system can be a metric
453 * that can be used to drive ballooning decisions when Linux is hosted
454 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
455 * balancing memory across competing virtual machines that are hosted.
456 * Several metrics drive this policy engine including the guest reported
457 * memory commitment.
458 */
459unsigned long vm_memory_committed(void)
460{
461	return percpu_counter_read_positive(&vm_committed_as);
462}
463EXPORT_SYMBOL_GPL(vm_memory_committed);
464
465/*
466 * Check that a process has enough memory to allocate a new virtual
467 * mapping. 0 means there is enough memory for the allocation to
468 * succeed and -ENOMEM implies there is not.
469 *
470 * We currently support three overcommit policies, which are set via the
471 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
472 *
473 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
474 * Additional code 2002 Jul 20 by Robert Love.
475 *
476 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
477 *
478 * Note this is a helper function intended to be used by LSMs which
479 * wish to use this logic.
480 */
481int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
482{
483	long free, allowed, reserve;
484
485	VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
486			-(s64)vm_committed_as_batch * num_online_cpus(),
487			"memory commitment underflow");
488
489	vm_acct_memory(pages);
490
491	/*
492	 * Sometimes we want to use more memory than we have
493	 */
494	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
495		return 0;
496
497	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
498		free = global_page_state(NR_FREE_PAGES);
499		free += global_page_state(NR_FILE_PAGES);
500
501		/*
502		 * shmem pages shouldn't be counted as free in this
503		 * case, they can't be purged, only swapped out, and
504		 * that won't affect the overall amount of available
505		 * memory in the system.
506		 */
507		free -= global_page_state(NR_SHMEM);
508
509		free += get_nr_swap_pages();
510
511		/*
512		 * Any slabs which are created with the
513		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
514		 * which are reclaimable, under pressure.  The dentry
515		 * cache and most inode caches should fall into this
516		 */
517		free += global_page_state(NR_SLAB_RECLAIMABLE);
 
 
 
 
 
 
 
518
519		/*
520		 * Leave reserved pages. The pages are not for anonymous pages.
521		 */
522		if (free <= totalreserve_pages)
523			goto error;
524		else
525			free -= totalreserve_pages;
526
527		/*
528		 * Reserve some for root
529		 */
530		if (!cap_sys_admin)
531			free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
532
533		if (free > pages)
534			return 0;
535
536		goto error;
537	}
538
539	allowed = vm_commit_limit();
540	/*
541	 * Reserve some for root
542	 */
543	if (!cap_sys_admin)
544		allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
545
546	/*
547	 * Don't let a single process grow so big a user can't recover
548	 */
549	if (mm) {
550		reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
551		allowed -= min_t(long, mm->total_vm / 32, reserve);
552	}
553
554	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
555		return 0;
556error:
557	vm_unacct_memory(pages);
558
559	return -ENOMEM;
560}
561
562/**
563 * get_cmdline() - copy the cmdline value to a buffer.
564 * @task:     the task whose cmdline value to copy.
565 * @buffer:   the buffer to copy to.
566 * @buflen:   the length of the buffer. Larger cmdline values are truncated
567 *            to this length.
568 * Returns the size of the cmdline field copied. Note that the copy does
569 * not guarantee an ending NULL byte.
570 */
571int get_cmdline(struct task_struct *task, char *buffer, int buflen)
572{
573	int res = 0;
574	unsigned int len;
575	struct mm_struct *mm = get_task_mm(task);
576	unsigned long arg_start, arg_end, env_start, env_end;
577	if (!mm)
578		goto out;
579	if (!mm->arg_end)
580		goto out_mm;	/* Shh! No looking before we're done */
581
582	down_read(&mm->mmap_sem);
583	arg_start = mm->arg_start;
584	arg_end = mm->arg_end;
585	env_start = mm->env_start;
586	env_end = mm->env_end;
587	up_read(&mm->mmap_sem);
588
589	len = arg_end - arg_start;
590
591	if (len > buflen)
592		len = buflen;
593
594	res = access_process_vm(task, arg_start, buffer, len, 0);
595
596	/*
597	 * If the nul at the end of args has been overwritten, then
598	 * assume application is using setproctitle(3).
599	 */
600	if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
601		len = strnlen(buffer, res);
602		if (len < res) {
603			res = len;
604		} else {
605			len = env_end - env_start;
606			if (len > buflen - res)
607				len = buflen - res;
608			res += access_process_vm(task, env_start,
609						 buffer+res, len, 0);
 
610			res = strnlen(buffer, res);
611		}
612	}
613out_mm:
614	mmput(mm);
615out:
616	return res;
617}
v4.17
  1#include <linux/mm.h>
  2#include <linux/slab.h>
  3#include <linux/string.h>
  4#include <linux/compiler.h>
  5#include <linux/export.h>
  6#include <linux/err.h>
  7#include <linux/sched.h>
  8#include <linux/sched/mm.h>
  9#include <linux/sched/task_stack.h>
 10#include <linux/security.h>
 11#include <linux/swap.h>
 12#include <linux/swapops.h>
 13#include <linux/mman.h>
 14#include <linux/hugetlb.h>
 15#include <linux/vmalloc.h>
 16#include <linux/userfaultfd_k.h>
 17
 18#include <asm/sections.h>
 19#include <linux/uaccess.h>
 20
 21#include "internal.h"
 22
 23static inline int is_kernel_rodata(unsigned long addr)
 24{
 25	return addr >= (unsigned long)__start_rodata &&
 26		addr < (unsigned long)__end_rodata;
 27}
 28
 29/**
 30 * kfree_const - conditionally free memory
 31 * @x: pointer to the memory
 32 *
 33 * Function calls kfree only if @x is not in .rodata section.
 34 */
 35void kfree_const(const void *x)
 36{
 37	if (!is_kernel_rodata((unsigned long)x))
 38		kfree(x);
 39}
 40EXPORT_SYMBOL(kfree_const);
 41
 42/**
 43 * kstrdup - allocate space for and copy an existing string
 44 * @s: the string to duplicate
 45 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 46 */
 47char *kstrdup(const char *s, gfp_t gfp)
 48{
 49	size_t len;
 50	char *buf;
 51
 52	if (!s)
 53		return NULL;
 54
 55	len = strlen(s) + 1;
 56	buf = kmalloc_track_caller(len, gfp);
 57	if (buf)
 58		memcpy(buf, s, len);
 59	return buf;
 60}
 61EXPORT_SYMBOL(kstrdup);
 62
 63/**
 64 * kstrdup_const - conditionally duplicate an existing const string
 65 * @s: the string to duplicate
 66 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 67 *
 68 * Function returns source string if it is in .rodata section otherwise it
 69 * fallbacks to kstrdup.
 70 * Strings allocated by kstrdup_const should be freed by kfree_const.
 71 */
 72const char *kstrdup_const(const char *s, gfp_t gfp)
 73{
 74	if (is_kernel_rodata((unsigned long)s))
 75		return s;
 76
 77	return kstrdup(s, gfp);
 78}
 79EXPORT_SYMBOL(kstrdup_const);
 80
 81/**
 82 * kstrndup - allocate space for and copy an existing string
 83 * @s: the string to duplicate
 84 * @max: read at most @max chars from @s
 85 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
 86 *
 87 * Note: Use kmemdup_nul() instead if the size is known exactly.
 88 */
 89char *kstrndup(const char *s, size_t max, gfp_t gfp)
 90{
 91	size_t len;
 92	char *buf;
 93
 94	if (!s)
 95		return NULL;
 96
 97	len = strnlen(s, max);
 98	buf = kmalloc_track_caller(len+1, gfp);
 99	if (buf) {
100		memcpy(buf, s, len);
101		buf[len] = '\0';
102	}
103	return buf;
104}
105EXPORT_SYMBOL(kstrndup);
106
107/**
108 * kmemdup - duplicate region of memory
109 *
110 * @src: memory region to duplicate
111 * @len: memory region length
112 * @gfp: GFP mask to use
113 */
114void *kmemdup(const void *src, size_t len, gfp_t gfp)
115{
116	void *p;
117
118	p = kmalloc_track_caller(len, gfp);
119	if (p)
120		memcpy(p, src, len);
121	return p;
122}
123EXPORT_SYMBOL(kmemdup);
124
125/**
126 * kmemdup_nul - Create a NUL-terminated string from unterminated data
127 * @s: The data to stringify
128 * @len: The size of the data
129 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
130 */
131char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
132{
133	char *buf;
134
135	if (!s)
136		return NULL;
137
138	buf = kmalloc_track_caller(len + 1, gfp);
139	if (buf) {
140		memcpy(buf, s, len);
141		buf[len] = '\0';
142	}
143	return buf;
144}
145EXPORT_SYMBOL(kmemdup_nul);
146
147/**
148 * memdup_user - duplicate memory region from user space
149 *
150 * @src: source address in user space
151 * @len: number of bytes to copy
152 *
153 * Returns an ERR_PTR() on failure.  Result is physically
154 * contiguous, to be freed by kfree().
155 */
156void *memdup_user(const void __user *src, size_t len)
157{
158	void *p;
159
160	p = kmalloc_track_caller(len, GFP_USER);
 
 
 
 
 
161	if (!p)
162		return ERR_PTR(-ENOMEM);
163
164	if (copy_from_user(p, src, len)) {
165		kfree(p);
166		return ERR_PTR(-EFAULT);
167	}
168
169	return p;
170}
171EXPORT_SYMBOL(memdup_user);
172
173/**
174 * vmemdup_user - duplicate memory region from user space
175 *
176 * @src: source address in user space
177 * @len: number of bytes to copy
178 *
179 * Returns an ERR_PTR() on failure.  Result may be not
180 * physically contiguous.  Use kvfree() to free.
181 */
182void *vmemdup_user(const void __user *src, size_t len)
183{
184	void *p;
185
186	p = kvmalloc(len, GFP_USER);
187	if (!p)
188		return ERR_PTR(-ENOMEM);
189
190	if (copy_from_user(p, src, len)) {
191		kvfree(p);
192		return ERR_PTR(-EFAULT);
193	}
194
195	return p;
196}
197EXPORT_SYMBOL(vmemdup_user);
198
199/*
200 * strndup_user - duplicate an existing string from user space
201 * @s: The string to duplicate
202 * @n: Maximum number of bytes to copy, including the trailing NUL.
203 */
204char *strndup_user(const char __user *s, long n)
205{
206	char *p;
207	long length;
208
209	length = strnlen_user(s, n);
210
211	if (!length)
212		return ERR_PTR(-EFAULT);
213
214	if (length > n)
215		return ERR_PTR(-EINVAL);
216
217	p = memdup_user(s, length);
218
219	if (IS_ERR(p))
220		return p;
221
222	p[length - 1] = '\0';
223
224	return p;
225}
226EXPORT_SYMBOL(strndup_user);
227
228/**
229 * memdup_user_nul - duplicate memory region from user space and NUL-terminate
230 *
231 * @src: source address in user space
232 * @len: number of bytes to copy
233 *
234 * Returns an ERR_PTR() on failure.
235 */
236void *memdup_user_nul(const void __user *src, size_t len)
237{
238	char *p;
239
240	/*
241	 * Always use GFP_KERNEL, since copy_from_user() can sleep and
242	 * cause pagefault, which makes it pointless to use GFP_NOFS
243	 * or GFP_ATOMIC.
244	 */
245	p = kmalloc_track_caller(len + 1, GFP_KERNEL);
246	if (!p)
247		return ERR_PTR(-ENOMEM);
248
249	if (copy_from_user(p, src, len)) {
250		kfree(p);
251		return ERR_PTR(-EFAULT);
252	}
253	p[len] = '\0';
254
255	return p;
256}
257EXPORT_SYMBOL(memdup_user_nul);
258
259void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
260		struct vm_area_struct *prev, struct rb_node *rb_parent)
261{
262	struct vm_area_struct *next;
263
264	vma->vm_prev = prev;
265	if (prev) {
266		next = prev->vm_next;
267		prev->vm_next = vma;
268	} else {
269		mm->mmap = vma;
270		if (rb_parent)
271			next = rb_entry(rb_parent,
272					struct vm_area_struct, vm_rb);
273		else
274			next = NULL;
275	}
276	vma->vm_next = next;
277	if (next)
278		next->vm_prev = vma;
279}
280
281/* Check if the vma is being used as a stack by this task */
282int vma_is_stack_for_current(struct vm_area_struct *vma)
283{
284	struct task_struct * __maybe_unused t = current;
285
286	return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
287}
288
289#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
290void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
291{
292	mm->mmap_base = TASK_UNMAPPED_BASE;
293	mm->get_unmapped_area = arch_get_unmapped_area;
294}
295#endif
296
297/*
298 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
299 * back to the regular GUP.
300 * Note a difference with get_user_pages_fast: this always returns the
301 * number of pages pinned, 0 if no pages were pinned.
302 * If the architecture does not support this function, simply return with no
303 * pages pinned.
304 */
305int __weak __get_user_pages_fast(unsigned long start,
306				 int nr_pages, int write, struct page **pages)
307{
308	return 0;
309}
310EXPORT_SYMBOL_GPL(__get_user_pages_fast);
311
312/**
313 * get_user_pages_fast() - pin user pages in memory
314 * @start:	starting user address
315 * @nr_pages:	number of pages from start to pin
316 * @write:	whether pages will be written to
317 * @pages:	array that receives pointers to the pages pinned.
318 *		Should be at least nr_pages long.
319 *
320 * Returns number of pages pinned. This may be fewer than the number
321 * requested. If nr_pages is 0 or negative, returns 0. If no pages
322 * were pinned, returns -errno.
323 *
324 * get_user_pages_fast provides equivalent functionality to get_user_pages,
325 * operating on current and current->mm, with force=0 and vma=NULL. However
326 * unlike get_user_pages, it must be called without mmap_sem held.
327 *
328 * get_user_pages_fast may take mmap_sem and page table locks, so no
329 * assumptions can be made about lack of locking. get_user_pages_fast is to be
330 * implemented in a way that is advantageous (vs get_user_pages()) when the
331 * user memory area is already faulted in and present in ptes. However if the
332 * pages have to be faulted in, it may turn out to be slightly slower so
333 * callers need to carefully consider what to use. On many architectures,
334 * get_user_pages_fast simply falls back to get_user_pages.
335 */
336int __weak get_user_pages_fast(unsigned long start,
337				int nr_pages, int write, struct page **pages)
338{
339	return get_user_pages_unlocked(start, nr_pages, pages,
340				       write ? FOLL_WRITE : 0);
341}
342EXPORT_SYMBOL_GPL(get_user_pages_fast);
343
344unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
345	unsigned long len, unsigned long prot,
346	unsigned long flag, unsigned long pgoff)
347{
348	unsigned long ret;
349	struct mm_struct *mm = current->mm;
350	unsigned long populate;
351	LIST_HEAD(uf);
352
353	ret = security_mmap_file(file, prot, flag);
354	if (!ret) {
355		if (down_write_killable(&mm->mmap_sem))
356			return -EINTR;
357		ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
358				    &populate, &uf);
359		up_write(&mm->mmap_sem);
360		userfaultfd_unmap_complete(mm, &uf);
361		if (populate)
362			mm_populate(ret, populate);
363	}
364	return ret;
365}
366
367unsigned long vm_mmap(struct file *file, unsigned long addr,
368	unsigned long len, unsigned long prot,
369	unsigned long flag, unsigned long offset)
370{
371	if (unlikely(offset + PAGE_ALIGN(len) < offset))
372		return -EINVAL;
373	if (unlikely(offset_in_page(offset)))
374		return -EINVAL;
375
376	return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
377}
378EXPORT_SYMBOL(vm_mmap);
379
380/**
381 * kvmalloc_node - attempt to allocate physically contiguous memory, but upon
382 * failure, fall back to non-contiguous (vmalloc) allocation.
383 * @size: size of the request.
384 * @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL.
385 * @node: numa node to allocate from
386 *
387 * Uses kmalloc to get the memory but if the allocation fails then falls back
388 * to the vmalloc allocator. Use kvfree for freeing the memory.
389 *
390 * Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported.
391 * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
392 * preferable to the vmalloc fallback, due to visible performance drawbacks.
393 *
394 * Any use of gfp flags outside of GFP_KERNEL should be consulted with mm people.
395 */
396void *kvmalloc_node(size_t size, gfp_t flags, int node)
397{
398	gfp_t kmalloc_flags = flags;
399	void *ret;
400
401	/*
402	 * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
403	 * so the given set of flags has to be compatible.
404	 */
405	WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
406
407	/*
408	 * We want to attempt a large physically contiguous block first because
409	 * it is less likely to fragment multiple larger blocks and therefore
410	 * contribute to a long term fragmentation less than vmalloc fallback.
411	 * However make sure that larger requests are not too disruptive - no
412	 * OOM killer and no allocation failure warnings as we have a fallback.
413	 */
414	if (size > PAGE_SIZE) {
415		kmalloc_flags |= __GFP_NOWARN;
416
417		if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
418			kmalloc_flags |= __GFP_NORETRY;
419	}
420
421	ret = kmalloc_node(size, kmalloc_flags, node);
422
423	/*
424	 * It doesn't really make sense to fallback to vmalloc for sub page
425	 * requests
426	 */
427	if (ret || size <= PAGE_SIZE)
428		return ret;
429
430	return __vmalloc_node_flags_caller(size, node, flags,
431			__builtin_return_address(0));
432}
433EXPORT_SYMBOL(kvmalloc_node);
434
435void kvfree(const void *addr)
436{
437	if (is_vmalloc_addr(addr))
438		vfree(addr);
439	else
440		kfree(addr);
441}
442EXPORT_SYMBOL(kvfree);
443
444static inline void *__page_rmapping(struct page *page)
445{
446	unsigned long mapping;
447
448	mapping = (unsigned long)page->mapping;
449	mapping &= ~PAGE_MAPPING_FLAGS;
450
451	return (void *)mapping;
452}
453
454/* Neutral page->mapping pointer to address_space or anon_vma or other */
455void *page_rmapping(struct page *page)
456{
457	page = compound_head(page);
458	return __page_rmapping(page);
459}
460
461/*
462 * Return true if this page is mapped into pagetables.
463 * For compound page it returns true if any subpage of compound page is mapped.
464 */
465bool page_mapped(struct page *page)
466{
467	int i;
468
469	if (likely(!PageCompound(page)))
470		return atomic_read(&page->_mapcount) >= 0;
471	page = compound_head(page);
472	if (atomic_read(compound_mapcount_ptr(page)) >= 0)
473		return true;
474	if (PageHuge(page))
475		return false;
476	for (i = 0; i < hpage_nr_pages(page); i++) {
477		if (atomic_read(&page[i]._mapcount) >= 0)
478			return true;
479	}
480	return false;
481}
482EXPORT_SYMBOL(page_mapped);
483
484struct anon_vma *page_anon_vma(struct page *page)
485{
486	unsigned long mapping;
487
488	page = compound_head(page);
489	mapping = (unsigned long)page->mapping;
490	if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
491		return NULL;
492	return __page_rmapping(page);
493}
494
495struct address_space *page_mapping(struct page *page)
496{
497	struct address_space *mapping;
498
499	page = compound_head(page);
500
501	/* This happens if someone calls flush_dcache_page on slab page */
502	if (unlikely(PageSlab(page)))
503		return NULL;
504
505	if (unlikely(PageSwapCache(page))) {
506		swp_entry_t entry;
507
508		entry.val = page_private(page);
509		return swap_address_space(entry);
510	}
511
512	mapping = page->mapping;
513	if ((unsigned long)mapping & PAGE_MAPPING_ANON)
514		return NULL;
515
516	return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS);
517}
518EXPORT_SYMBOL(page_mapping);
519
520/*
521 * For file cache pages, return the address_space, otherwise return NULL
522 */
523struct address_space *page_mapping_file(struct page *page)
524{
525	if (unlikely(PageSwapCache(page)))
526		return NULL;
527	return page_mapping(page);
528}
529
530/* Slow path of page_mapcount() for compound pages */
531int __page_mapcount(struct page *page)
532{
533	int ret;
534
535	ret = atomic_read(&page->_mapcount) + 1;
536	/*
537	 * For file THP page->_mapcount contains total number of mapping
538	 * of the page: no need to look into compound_mapcount.
539	 */
540	if (!PageAnon(page) && !PageHuge(page))
541		return ret;
542	page = compound_head(page);
543	ret += atomic_read(compound_mapcount_ptr(page)) + 1;
544	if (PageDoubleMap(page))
545		ret--;
546	return ret;
547}
548EXPORT_SYMBOL_GPL(__page_mapcount);
549
550int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
551int sysctl_overcommit_ratio __read_mostly = 50;
552unsigned long sysctl_overcommit_kbytes __read_mostly;
553int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
554unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
555unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
556
557int overcommit_ratio_handler(struct ctl_table *table, int write,
558			     void __user *buffer, size_t *lenp,
559			     loff_t *ppos)
560{
561	int ret;
562
563	ret = proc_dointvec(table, write, buffer, lenp, ppos);
564	if (ret == 0 && write)
565		sysctl_overcommit_kbytes = 0;
566	return ret;
567}
568
569int overcommit_kbytes_handler(struct ctl_table *table, int write,
570			     void __user *buffer, size_t *lenp,
571			     loff_t *ppos)
572{
573	int ret;
574
575	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
576	if (ret == 0 && write)
577		sysctl_overcommit_ratio = 0;
578	return ret;
579}
580
581/*
582 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
583 */
584unsigned long vm_commit_limit(void)
585{
586	unsigned long allowed;
587
588	if (sysctl_overcommit_kbytes)
589		allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
590	else
591		allowed = ((totalram_pages - hugetlb_total_pages())
592			   * sysctl_overcommit_ratio / 100);
593	allowed += total_swap_pages;
594
595	return allowed;
596}
597
598/*
599 * Make sure vm_committed_as in one cacheline and not cacheline shared with
600 * other variables. It can be updated by several CPUs frequently.
601 */
602struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
603
604/*
605 * The global memory commitment made in the system can be a metric
606 * that can be used to drive ballooning decisions when Linux is hosted
607 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
608 * balancing memory across competing virtual machines that are hosted.
609 * Several metrics drive this policy engine including the guest reported
610 * memory commitment.
611 */
612unsigned long vm_memory_committed(void)
613{
614	return percpu_counter_read_positive(&vm_committed_as);
615}
616EXPORT_SYMBOL_GPL(vm_memory_committed);
617
618/*
619 * Check that a process has enough memory to allocate a new virtual
620 * mapping. 0 means there is enough memory for the allocation to
621 * succeed and -ENOMEM implies there is not.
622 *
623 * We currently support three overcommit policies, which are set via the
624 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
625 *
626 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
627 * Additional code 2002 Jul 20 by Robert Love.
628 *
629 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
630 *
631 * Note this is a helper function intended to be used by LSMs which
632 * wish to use this logic.
633 */
634int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
635{
636	long free, allowed, reserve;
637
638	VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
639			-(s64)vm_committed_as_batch * num_online_cpus(),
640			"memory commitment underflow");
641
642	vm_acct_memory(pages);
643
644	/*
645	 * Sometimes we want to use more memory than we have
646	 */
647	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
648		return 0;
649
650	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
651		free = global_zone_page_state(NR_FREE_PAGES);
652		free += global_node_page_state(NR_FILE_PAGES);
653
654		/*
655		 * shmem pages shouldn't be counted as free in this
656		 * case, they can't be purged, only swapped out, and
657		 * that won't affect the overall amount of available
658		 * memory in the system.
659		 */
660		free -= global_node_page_state(NR_SHMEM);
661
662		free += get_nr_swap_pages();
663
664		/*
665		 * Any slabs which are created with the
666		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
667		 * which are reclaimable, under pressure.  The dentry
668		 * cache and most inode caches should fall into this
669		 */
670		free += global_node_page_state(NR_SLAB_RECLAIMABLE);
671
672		/*
673		 * Part of the kernel memory, which can be released
674		 * under memory pressure.
675		 */
676		free += global_node_page_state(
677			NR_INDIRECTLY_RECLAIMABLE_BYTES) >> PAGE_SHIFT;
678
679		/*
680		 * Leave reserved pages. The pages are not for anonymous pages.
681		 */
682		if (free <= totalreserve_pages)
683			goto error;
684		else
685			free -= totalreserve_pages;
686
687		/*
688		 * Reserve some for root
689		 */
690		if (!cap_sys_admin)
691			free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
692
693		if (free > pages)
694			return 0;
695
696		goto error;
697	}
698
699	allowed = vm_commit_limit();
700	/*
701	 * Reserve some for root
702	 */
703	if (!cap_sys_admin)
704		allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
705
706	/*
707	 * Don't let a single process grow so big a user can't recover
708	 */
709	if (mm) {
710		reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
711		allowed -= min_t(long, mm->total_vm / 32, reserve);
712	}
713
714	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
715		return 0;
716error:
717	vm_unacct_memory(pages);
718
719	return -ENOMEM;
720}
721
722/**
723 * get_cmdline() - copy the cmdline value to a buffer.
724 * @task:     the task whose cmdline value to copy.
725 * @buffer:   the buffer to copy to.
726 * @buflen:   the length of the buffer. Larger cmdline values are truncated
727 *            to this length.
728 * Returns the size of the cmdline field copied. Note that the copy does
729 * not guarantee an ending NULL byte.
730 */
731int get_cmdline(struct task_struct *task, char *buffer, int buflen)
732{
733	int res = 0;
734	unsigned int len;
735	struct mm_struct *mm = get_task_mm(task);
736	unsigned long arg_start, arg_end, env_start, env_end;
737	if (!mm)
738		goto out;
739	if (!mm->arg_end)
740		goto out_mm;	/* Shh! No looking before we're done */
741
742	down_read(&mm->mmap_sem);
743	arg_start = mm->arg_start;
744	arg_end = mm->arg_end;
745	env_start = mm->env_start;
746	env_end = mm->env_end;
747	up_read(&mm->mmap_sem);
748
749	len = arg_end - arg_start;
750
751	if (len > buflen)
752		len = buflen;
753
754	res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
755
756	/*
757	 * If the nul at the end of args has been overwritten, then
758	 * assume application is using setproctitle(3).
759	 */
760	if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
761		len = strnlen(buffer, res);
762		if (len < res) {
763			res = len;
764		} else {
765			len = env_end - env_start;
766			if (len > buflen - res)
767				len = buflen - res;
768			res += access_process_vm(task, env_start,
769						 buffer+res, len,
770						 FOLL_FORCE);
771			res = strnlen(buffer, res);
772		}
773	}
774out_mm:
775	mmput(mm);
776out:
777	return res;
778}