]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - mm/util.c
2 #include <linux/slab.h>
3 #include <linux/string.h>
4 #include <linux/module.h>
6 #include <linux/sched.h>
7 #include <asm/uaccess.h>
10 * kstrdup - allocate space for and copy an existing string
11 * @s: the string to duplicate
12 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
14 char *kstrdup(const char *s
, gfp_t gfp
)
23 buf
= kmalloc_track_caller(len
, gfp
);
28 EXPORT_SYMBOL(kstrdup
);
31 * kstrndup - allocate space for and copy an existing string
32 * @s: the string to duplicate
33 * @max: read at most @max chars from @s
34 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
36 char *kstrndup(const char *s
, size_t max
, gfp_t gfp
)
44 len
= strnlen(s
, max
);
45 buf
= kmalloc_track_caller(len
+1, gfp
);
52 EXPORT_SYMBOL(kstrndup
);
55 * kmemdup - duplicate region of memory
57 * @src: memory region to duplicate
58 * @len: memory region length
59 * @gfp: GFP mask to use
61 void *kmemdup(const void *src
, size_t len
, gfp_t gfp
)
65 p
= kmalloc_track_caller(len
, gfp
);
70 EXPORT_SYMBOL(kmemdup
);
73 * memdup_user - duplicate memory region from user space
75 * @src: source address in user space
76 * @len: number of bytes to copy
78 * Returns an ERR_PTR() on failure.
80 void *memdup_user(const void __user
*src
, size_t len
)
85 * Always use GFP_KERNEL, since copy_from_user() can sleep and
86 * cause pagefault, which makes it pointless to use GFP_NOFS
89 p
= kmalloc_track_caller(len
, GFP_KERNEL
);
91 return ERR_PTR(-ENOMEM
);
93 if (copy_from_user(p
, src
, len
)) {
95 return ERR_PTR(-EFAULT
);
100 EXPORT_SYMBOL(memdup_user
);
103 * __krealloc - like krealloc() but don't free @p.
104 * @p: object to reallocate memory for.
105 * @new_size: how many bytes of memory are required.
106 * @flags: the type of memory to allocate.
108 * This function is like krealloc() except it never frees the originally
109 * allocated buffer. Use this if you don't want to free the buffer immediately
110 * like, for example, with RCU.
112 void *__krealloc(const void *p
, size_t new_size
, gfp_t flags
)
117 if (unlikely(!new_size
))
118 return ZERO_SIZE_PTR
;
126 ret
= kmalloc_track_caller(new_size
, flags
);
132 EXPORT_SYMBOL(__krealloc
);
135 * krealloc - reallocate memory. The contents will remain unchanged.
136 * @p: object to reallocate memory for.
137 * @new_size: how many bytes of memory are required.
138 * @flags: the type of memory to allocate.
140 * The contents of the object pointed to are preserved up to the
141 * lesser of the new and old sizes. If @p is %NULL, krealloc()
142 * behaves exactly like kmalloc(). If @size is 0 and @p is not a
143 * %NULL pointer, the object pointed to is freed.
145 void *krealloc(const void *p
, size_t new_size
, gfp_t flags
)
149 if (unlikely(!new_size
)) {
151 return ZERO_SIZE_PTR
;
154 ret
= __krealloc(p
, new_size
, flags
);
160 EXPORT_SYMBOL(krealloc
);
163 * kzfree - like kfree but zero memory
164 * @p: object to free memory of
166 * The memory of the object @p points to is zeroed before freed.
167 * If @p is %NULL, kzfree() does nothing.
169 void kzfree(const void *p
)
172 void *mem
= (void *)p
;
174 if (unlikely(ZERO_OR_NULL_PTR(mem
)))
180 EXPORT_SYMBOL(kzfree
);
183 * strndup_user - duplicate an existing string from user space
184 * @s: The string to duplicate
185 * @n: Maximum number of bytes to copy, including the trailing NUL.
187 char *strndup_user(const char __user
*s
, long n
)
192 length
= strnlen_user(s
, n
);
195 return ERR_PTR(-EFAULT
);
198 return ERR_PTR(-EINVAL
);
200 p
= kmalloc(length
, GFP_KERNEL
);
203 return ERR_PTR(-ENOMEM
);
205 if (copy_from_user(p
, s
, length
)) {
207 return ERR_PTR(-EFAULT
);
210 p
[length
- 1] = '\0';
214 EXPORT_SYMBOL(strndup_user
);
216 #ifndef HAVE_ARCH_PICK_MMAP_LAYOUT
217 void arch_pick_mmap_layout(struct mm_struct
*mm
)
219 mm
->mmap_base
= TASK_UNMAPPED_BASE
;
220 mm
->get_unmapped_area
= arch_get_unmapped_area
;
221 mm
->unmap_area
= arch_unmap_area
;
225 int __attribute__((weak
)) get_user_pages_fast(unsigned long start
,
226 int nr_pages
, int write
, struct page
**pages
)
228 struct mm_struct
*mm
= current
->mm
;
231 down_read(&mm
->mmap_sem
);
232 ret
= get_user_pages(current
, mm
, start
, nr_pages
,
233 write
, 0, pages
, NULL
);
234 up_read(&mm
->mmap_sem
);
238 EXPORT_SYMBOL_GPL(get_user_pages_fast
);