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/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>
15 #include <asm/sections.h>
16 #include <asm/uaccess.h>
20 static inline int is_kernel_rodata(unsigned long addr
)
22 return addr
>= (unsigned long)__start_rodata
&&
23 addr
< (unsigned long)__end_rodata
;
27 * kfree_const - conditionally free memory
28 * @x: pointer to the memory
30 * Function calls kfree only if @x is not in .rodata section.
32 void kfree_const(const void *x
)
34 if (!is_kernel_rodata((unsigned long)x
))
37 EXPORT_SYMBOL(kfree_const
);
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
44 char *kstrdup(const char *s
, gfp_t gfp
)
53 buf
= kmalloc_track_caller(len
, gfp
);
58 EXPORT_SYMBOL(kstrdup
);
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
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.
69 const char *kstrdup_const(const char *s
, gfp_t gfp
)
71 if (is_kernel_rodata((unsigned long)s
))
74 return kstrdup(s
, gfp
);
76 EXPORT_SYMBOL(kstrdup_const
);
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
84 * Note: Use kmemdup_nul() instead if the size is known exactly.
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 * kmemdup_nul - Create a NUL-terminated string from unterminated data
124 * @s: The data to stringify
125 * @len: The size of the data
126 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
128 char *kmemdup_nul(const char *s
, size_t len
, gfp_t gfp
)
135 buf
= kmalloc_track_caller(len
+ 1, gfp
);
142 EXPORT_SYMBOL(kmemdup_nul
);
145 * memdup_user - duplicate memory region from user space
147 * @src: source address in user space
148 * @len: number of bytes to copy
150 * Returns an ERR_PTR() on failure.
152 void *memdup_user(const void __user
*src
, size_t len
)
157 * Always use GFP_KERNEL, since copy_from_user() can sleep and
158 * cause pagefault, which makes it pointless to use GFP_NOFS
161 p
= kmalloc_track_caller(len
, GFP_KERNEL
);
163 return ERR_PTR(-ENOMEM
);
165 if (copy_from_user(p
, src
, len
)) {
167 return ERR_PTR(-EFAULT
);
172 EXPORT_SYMBOL(memdup_user
);
175 * strndup_user - duplicate an existing string from user space
176 * @s: The string to duplicate
177 * @n: Maximum number of bytes to copy, including the trailing NUL.
179 char *strndup_user(const char __user
*s
, long n
)
184 length
= strnlen_user(s
, n
);
187 return ERR_PTR(-EFAULT
);
190 return ERR_PTR(-EINVAL
);
192 p
= memdup_user(s
, length
);
197 p
[length
- 1] = '\0';
201 EXPORT_SYMBOL(strndup_user
);
203 void __vma_link_list(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
204 struct vm_area_struct
*prev
, struct rb_node
*rb_parent
)
206 struct vm_area_struct
*next
;
210 next
= prev
->vm_next
;
215 next
= rb_entry(rb_parent
,
216 struct vm_area_struct
, vm_rb
);
225 /* Check if the vma is being used as a stack by this task */
226 int vma_is_stack_for_task(struct vm_area_struct
*vma
, struct task_struct
*t
)
228 return (vma
->vm_start
<= KSTK_ESP(t
) && vma
->vm_end
>= KSTK_ESP(t
));
231 #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
232 void arch_pick_mmap_layout(struct mm_struct
*mm
)
234 mm
->mmap_base
= TASK_UNMAPPED_BASE
;
235 mm
->get_unmapped_area
= arch_get_unmapped_area
;
240 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
241 * back to the regular GUP.
242 * If the architecture not support this function, simply return with no
245 int __weak
__get_user_pages_fast(unsigned long start
,
246 int nr_pages
, int write
, struct page
**pages
)
250 EXPORT_SYMBOL_GPL(__get_user_pages_fast
);
253 * get_user_pages_fast() - pin user pages in memory
254 * @start: starting user address
255 * @nr_pages: number of pages from start to pin
256 * @write: whether pages will be written to
257 * @pages: array that receives pointers to the pages pinned.
258 * Should be at least nr_pages long.
260 * Returns number of pages pinned. This may be fewer than the number
261 * requested. If nr_pages is 0 or negative, returns 0. If no pages
262 * were pinned, returns -errno.
264 * get_user_pages_fast provides equivalent functionality to get_user_pages,
265 * operating on current and current->mm, with force=0 and vma=NULL. However
266 * unlike get_user_pages, it must be called without mmap_sem held.
268 * get_user_pages_fast may take mmap_sem and page table locks, so no
269 * assumptions can be made about lack of locking. get_user_pages_fast is to be
270 * implemented in a way that is advantageous (vs get_user_pages()) when the
271 * user memory area is already faulted in and present in ptes. However if the
272 * pages have to be faulted in, it may turn out to be slightly slower so
273 * callers need to carefully consider what to use. On many architectures,
274 * get_user_pages_fast simply falls back to get_user_pages.
276 int __weak
get_user_pages_fast(unsigned long start
,
277 int nr_pages
, int write
, struct page
**pages
)
279 struct mm_struct
*mm
= current
->mm
;
280 return get_user_pages_unlocked(current
, mm
, start
, nr_pages
,
283 EXPORT_SYMBOL_GPL(get_user_pages_fast
);
285 unsigned long vm_mmap_pgoff(struct file
*file
, unsigned long addr
,
286 unsigned long len
, unsigned long prot
,
287 unsigned long flag
, unsigned long pgoff
)
290 struct mm_struct
*mm
= current
->mm
;
291 unsigned long populate
;
293 ret
= security_mmap_file(file
, prot
, flag
);
295 down_write(&mm
->mmap_sem
);
296 ret
= do_mmap_pgoff(file
, addr
, len
, prot
, flag
, pgoff
,
298 up_write(&mm
->mmap_sem
);
300 mm_populate(ret
, populate
);
305 unsigned long vm_mmap(struct file
*file
, unsigned long addr
,
306 unsigned long len
, unsigned long prot
,
307 unsigned long flag
, unsigned long offset
)
309 if (unlikely(offset
+ PAGE_ALIGN(len
) < offset
))
311 if (unlikely(offset_in_page(offset
)))
314 return vm_mmap_pgoff(file
, addr
, len
, prot
, flag
, offset
>> PAGE_SHIFT
);
316 EXPORT_SYMBOL(vm_mmap
);
318 void kvfree(const void *addr
)
320 if (is_vmalloc_addr(addr
))
325 EXPORT_SYMBOL(kvfree
);
327 static inline void *__page_rmapping(struct page
*page
)
329 unsigned long mapping
;
331 mapping
= (unsigned long)page
->mapping
;
332 mapping
&= ~PAGE_MAPPING_FLAGS
;
334 return (void *)mapping
;
337 /* Neutral page->mapping pointer to address_space or anon_vma or other */
338 void *page_rmapping(struct page
*page
)
340 page
= compound_head(page
);
341 return __page_rmapping(page
);
344 struct anon_vma
*page_anon_vma(struct page
*page
)
346 unsigned long mapping
;
348 page
= compound_head(page
);
349 mapping
= (unsigned long)page
->mapping
;
350 if ((mapping
& PAGE_MAPPING_FLAGS
) != PAGE_MAPPING_ANON
)
352 return __page_rmapping(page
);
355 struct address_space
*page_mapping(struct page
*page
)
357 unsigned long mapping
;
359 /* This happens if someone calls flush_dcache_page on slab page */
360 if (unlikely(PageSlab(page
)))
363 if (unlikely(PageSwapCache(page
))) {
366 entry
.val
= page_private(page
);
367 return swap_address_space(entry
);
370 mapping
= (unsigned long)page
->mapping
;
371 if (mapping
& PAGE_MAPPING_FLAGS
)
373 return page
->mapping
;
376 int overcommit_ratio_handler(struct ctl_table
*table
, int write
,
377 void __user
*buffer
, size_t *lenp
,
382 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
383 if (ret
== 0 && write
)
384 sysctl_overcommit_kbytes
= 0;
388 int overcommit_kbytes_handler(struct ctl_table
*table
, int write
,
389 void __user
*buffer
, size_t *lenp
,
394 ret
= proc_doulongvec_minmax(table
, write
, buffer
, lenp
, ppos
);
395 if (ret
== 0 && write
)
396 sysctl_overcommit_ratio
= 0;
401 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
403 unsigned long vm_commit_limit(void)
405 unsigned long allowed
;
407 if (sysctl_overcommit_kbytes
)
408 allowed
= sysctl_overcommit_kbytes
>> (PAGE_SHIFT
- 10);
410 allowed
= ((totalram_pages
- hugetlb_total_pages())
411 * sysctl_overcommit_ratio
/ 100);
412 allowed
+= total_swap_pages
;
418 * get_cmdline() - copy the cmdline value to a buffer.
419 * @task: the task whose cmdline value to copy.
420 * @buffer: the buffer to copy to.
421 * @buflen: the length of the buffer. Larger cmdline values are truncated
423 * Returns the size of the cmdline field copied. Note that the copy does
424 * not guarantee an ending NULL byte.
426 int get_cmdline(struct task_struct
*task
, char *buffer
, int buflen
)
430 struct mm_struct
*mm
= get_task_mm(task
);
431 unsigned long arg_start
, arg_end
, env_start
, env_end
;
435 goto out_mm
; /* Shh! No looking before we're done */
437 down_read(&mm
->mmap_sem
);
438 arg_start
= mm
->arg_start
;
439 arg_end
= mm
->arg_end
;
440 env_start
= mm
->env_start
;
441 env_end
= mm
->env_end
;
442 up_read(&mm
->mmap_sem
);
444 len
= arg_end
- arg_start
;
449 res
= access_process_vm(task
, arg_start
, buffer
, len
, 0);
452 * If the nul at the end of args has been overwritten, then
453 * assume application is using setproctitle(3).
455 if (res
> 0 && buffer
[res
-1] != '\0' && len
< buflen
) {
456 len
= strnlen(buffer
, res
);
460 len
= env_end
- env_start
;
461 if (len
> buflen
- res
)
463 res
+= access_process_vm(task
, env_start
,
465 res
= strnlen(buffer
, res
);