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Merge tag 'xtensa-20150830' of git://github.com/czankel/xtensa-linux
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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
20 static 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 */
32 void kfree_const(const void *x)
33 {
34 if (!is_kernel_rodata((unsigned long)x))
35 kfree(x);
36 }
37 EXPORT_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 */
44 char *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 }
58 EXPORT_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 */
69 const 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 }
76 EXPORT_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 */
84 char *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 }
100 EXPORT_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 */
109 void *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 }
118 EXPORT_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 */
128 void *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 }
148 EXPORT_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 */
155 char *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 }
177 EXPORT_SYMBOL(strndup_user);
178
179 void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
180 struct vm_area_struct *prev, struct rb_node *rb_parent)
181 {
182 struct vm_area_struct *next;
183
184 vma->vm_prev = prev;
185 if (prev) {
186 next = prev->vm_next;
187 prev->vm_next = vma;
188 } else {
189 mm->mmap = vma;
190 if (rb_parent)
191 next = rb_entry(rb_parent,
192 struct vm_area_struct, vm_rb);
193 else
194 next = NULL;
195 }
196 vma->vm_next = next;
197 if (next)
198 next->vm_prev = vma;
199 }
200
201 /* Check if the vma is being used as a stack by this task */
202 static int vm_is_stack_for_task(struct task_struct *t,
203 struct vm_area_struct *vma)
204 {
205 return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
206 }
207
208 /*
209 * Check if the vma is being used as a stack.
210 * If is_group is non-zero, check in the entire thread group or else
211 * just check in the current task. Returns the task_struct of the task
212 * that the vma is stack for. Must be called under rcu_read_lock().
213 */
214 struct task_struct *task_of_stack(struct task_struct *task,
215 struct vm_area_struct *vma, bool in_group)
216 {
217 if (vm_is_stack_for_task(task, vma))
218 return task;
219
220 if (in_group) {
221 struct task_struct *t;
222
223 for_each_thread(task, t) {
224 if (vm_is_stack_for_task(t, vma))
225 return t;
226 }
227 }
228
229 return NULL;
230 }
231
232 #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
233 void arch_pick_mmap_layout(struct mm_struct *mm)
234 {
235 mm->mmap_base = TASK_UNMAPPED_BASE;
236 mm->get_unmapped_area = arch_get_unmapped_area;
237 }
238 #endif
239
240 /*
241 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
242 * back to the regular GUP.
243 * If the architecture not support this function, simply return with no
244 * page pinned
245 */
246 int __weak __get_user_pages_fast(unsigned long start,
247 int nr_pages, int write, struct page **pages)
248 {
249 return 0;
250 }
251 EXPORT_SYMBOL_GPL(__get_user_pages_fast);
252
253 /**
254 * get_user_pages_fast() - pin user pages in memory
255 * @start: starting user address
256 * @nr_pages: number of pages from start to pin
257 * @write: whether pages will be written to
258 * @pages: array that receives pointers to the pages pinned.
259 * Should be at least nr_pages long.
260 *
261 * Returns number of pages pinned. This may be fewer than the number
262 * requested. If nr_pages is 0 or negative, returns 0. If no pages
263 * were pinned, returns -errno.
264 *
265 * get_user_pages_fast provides equivalent functionality to get_user_pages,
266 * operating on current and current->mm, with force=0 and vma=NULL. However
267 * unlike get_user_pages, it must be called without mmap_sem held.
268 *
269 * get_user_pages_fast may take mmap_sem and page table locks, so no
270 * assumptions can be made about lack of locking. get_user_pages_fast is to be
271 * implemented in a way that is advantageous (vs get_user_pages()) when the
272 * user memory area is already faulted in and present in ptes. However if the
273 * pages have to be faulted in, it may turn out to be slightly slower so
274 * callers need to carefully consider what to use. On many architectures,
275 * get_user_pages_fast simply falls back to get_user_pages.
276 */
277 int __weak get_user_pages_fast(unsigned long start,
278 int nr_pages, int write, struct page **pages)
279 {
280 struct mm_struct *mm = current->mm;
281 return get_user_pages_unlocked(current, mm, start, nr_pages,
282 write, 0, pages);
283 }
284 EXPORT_SYMBOL_GPL(get_user_pages_fast);
285
286 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
287 unsigned long len, unsigned long prot,
288 unsigned long flag, unsigned long pgoff)
289 {
290 unsigned long ret;
291 struct mm_struct *mm = current->mm;
292 unsigned long populate;
293
294 ret = security_mmap_file(file, prot, flag);
295 if (!ret) {
296 down_write(&mm->mmap_sem);
297 ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
298 &populate);
299 up_write(&mm->mmap_sem);
300 if (populate)
301 mm_populate(ret, populate);
302 }
303 return ret;
304 }
305
306 unsigned long vm_mmap(struct file *file, unsigned long addr,
307 unsigned long len, unsigned long prot,
308 unsigned long flag, unsigned long offset)
309 {
310 if (unlikely(offset + PAGE_ALIGN(len) < offset))
311 return -EINVAL;
312 if (unlikely(offset & ~PAGE_MASK))
313 return -EINVAL;
314
315 return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
316 }
317 EXPORT_SYMBOL(vm_mmap);
318
319 void kvfree(const void *addr)
320 {
321 if (is_vmalloc_addr(addr))
322 vfree(addr);
323 else
324 kfree(addr);
325 }
326 EXPORT_SYMBOL(kvfree);
327
328 static inline void *__page_rmapping(struct page *page)
329 {
330 unsigned long mapping;
331
332 mapping = (unsigned long)page->mapping;
333 mapping &= ~PAGE_MAPPING_FLAGS;
334
335 return (void *)mapping;
336 }
337
338 /* Neutral page->mapping pointer to address_space or anon_vma or other */
339 void *page_rmapping(struct page *page)
340 {
341 page = compound_head(page);
342 return __page_rmapping(page);
343 }
344
345 struct anon_vma *page_anon_vma(struct page *page)
346 {
347 unsigned long mapping;
348
349 page = compound_head(page);
350 mapping = (unsigned long)page->mapping;
351 if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
352 return NULL;
353 return __page_rmapping(page);
354 }
355
356 struct address_space *page_mapping(struct page *page)
357 {
358 unsigned long mapping;
359
360 /* This happens if someone calls flush_dcache_page on slab page */
361 if (unlikely(PageSlab(page)))
362 return NULL;
363
364 if (unlikely(PageSwapCache(page))) {
365 swp_entry_t entry;
366
367 entry.val = page_private(page);
368 return swap_address_space(entry);
369 }
370
371 mapping = (unsigned long)page->mapping;
372 if (mapping & PAGE_MAPPING_FLAGS)
373 return NULL;
374 return page->mapping;
375 }
376
377 int overcommit_ratio_handler(struct ctl_table *table, int write,
378 void __user *buffer, size_t *lenp,
379 loff_t *ppos)
380 {
381 int ret;
382
383 ret = proc_dointvec(table, write, buffer, lenp, ppos);
384 if (ret == 0 && write)
385 sysctl_overcommit_kbytes = 0;
386 return ret;
387 }
388
389 int overcommit_kbytes_handler(struct ctl_table *table, int write,
390 void __user *buffer, size_t *lenp,
391 loff_t *ppos)
392 {
393 int ret;
394
395 ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
396 if (ret == 0 && write)
397 sysctl_overcommit_ratio = 0;
398 return ret;
399 }
400
401 /*
402 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
403 */
404 unsigned long vm_commit_limit(void)
405 {
406 unsigned long allowed;
407
408 if (sysctl_overcommit_kbytes)
409 allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
410 else
411 allowed = ((totalram_pages - hugetlb_total_pages())
412 * sysctl_overcommit_ratio / 100);
413 allowed += total_swap_pages;
414
415 return allowed;
416 }
417
418 /**
419 * get_cmdline() - copy the cmdline value to a buffer.
420 * @task: the task whose cmdline value to copy.
421 * @buffer: the buffer to copy to.
422 * @buflen: the length of the buffer. Larger cmdline values are truncated
423 * to this length.
424 * Returns the size of the cmdline field copied. Note that the copy does
425 * not guarantee an ending NULL byte.
426 */
427 int get_cmdline(struct task_struct *task, char *buffer, int buflen)
428 {
429 int res = 0;
430 unsigned int len;
431 struct mm_struct *mm = get_task_mm(task);
432 if (!mm)
433 goto out;
434 if (!mm->arg_end)
435 goto out_mm; /* Shh! No looking before we're done */
436
437 len = mm->arg_end - mm->arg_start;
438
439 if (len > buflen)
440 len = buflen;
441
442 res = access_process_vm(task, mm->arg_start, buffer, len, 0);
443
444 /*
445 * If the nul at the end of args has been overwritten, then
446 * assume application is using setproctitle(3).
447 */
448 if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
449 len = strnlen(buffer, res);
450 if (len < res) {
451 res = len;
452 } else {
453 len = mm->env_end - mm->env_start;
454 if (len > buflen - res)
455 len = buflen - res;
456 res += access_process_vm(task, mm->env_start,
457 buffer+res, len, 0);
458 res = strnlen(buffer, res);
459 }
460 }
461 out_mm:
462 mmput(mm);
463 out:
464 return res;
465 }