Root/mm/util.c

1#include <linux/mm.h>
2#include <linux/slab.h>
3#include <linux/string.h>
4#include <linux/export.h>
5#include <linux/err.h>
6#include <linux/sched.h>
7#include <linux/security.h>
8#include <linux/swap.h>
9#include <linux/swapops.h>
10#include <asm/uaccess.h>
11
12#include "internal.h"
13
14#define CREATE_TRACE_POINTS
15#include <trace/events/kmem.h>
16
17/**
18 * kstrdup - allocate space for and copy an existing string
19 * @s: the string to duplicate
20 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
21 */
22char *kstrdup(const char *s, gfp_t gfp)
23{
24    size_t len;
25    char *buf;
26
27    if (!s)
28        return NULL;
29
30    len = strlen(s) + 1;
31    buf = kmalloc_track_caller(len, gfp);
32    if (buf)
33        memcpy(buf, s, len);
34    return buf;
35}
36EXPORT_SYMBOL(kstrdup);
37
38/**
39 * kstrndup - allocate space for and copy an existing string
40 * @s: the string to duplicate
41 * @max: read at most @max chars from @s
42 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
43 */
44char *kstrndup(const char *s, size_t max, gfp_t gfp)
45{
46    size_t len;
47    char *buf;
48
49    if (!s)
50        return NULL;
51
52    len = strnlen(s, max);
53    buf = kmalloc_track_caller(len+1, gfp);
54    if (buf) {
55        memcpy(buf, s, len);
56        buf[len] = '\0';
57    }
58    return buf;
59}
60EXPORT_SYMBOL(kstrndup);
61
62/**
63 * kmemdup - duplicate region of memory
64 *
65 * @src: memory region to duplicate
66 * @len: memory region length
67 * @gfp: GFP mask to use
68 */
69void *kmemdup(const void *src, size_t len, gfp_t gfp)
70{
71    void *p;
72
73    p = kmalloc_track_caller(len, gfp);
74    if (p)
75        memcpy(p, src, len);
76    return p;
77}
78EXPORT_SYMBOL(kmemdup);
79
80/**
81 * memdup_user - duplicate memory region from user space
82 *
83 * @src: source address in user space
84 * @len: number of bytes to copy
85 *
86 * Returns an ERR_PTR() on failure.
87 */
88void *memdup_user(const void __user *src, size_t len)
89{
90    void *p;
91
92    /*
93     * Always use GFP_KERNEL, since copy_from_user() can sleep and
94     * cause pagefault, which makes it pointless to use GFP_NOFS
95     * or GFP_ATOMIC.
96     */
97    p = kmalloc_track_caller(len, GFP_KERNEL);
98    if (!p)
99        return ERR_PTR(-ENOMEM);
100
101    if (copy_from_user(p, src, len)) {
102        kfree(p);
103        return ERR_PTR(-EFAULT);
104    }
105
106    return p;
107}
108EXPORT_SYMBOL(memdup_user);
109
110static __always_inline void *__do_krealloc(const void *p, size_t new_size,
111                       gfp_t flags)
112{
113    void *ret;
114    size_t ks = 0;
115
116    if (p)
117        ks = ksize(p);
118
119    if (ks >= new_size)
120        return (void *)p;
121
122    ret = kmalloc_track_caller(new_size, flags);
123    if (ret && p)
124        memcpy(ret, p, ks);
125
126    return ret;
127}
128
129/**
130 * __krealloc - like krealloc() but don't free @p.
131 * @p: object to reallocate memory for.
132 * @new_size: how many bytes of memory are required.
133 * @flags: the type of memory to allocate.
134 *
135 * This function is like krealloc() except it never frees the originally
136 * allocated buffer. Use this if you don't want to free the buffer immediately
137 * like, for example, with RCU.
138 */
139void *__krealloc(const void *p, size_t new_size, gfp_t flags)
140{
141    if (unlikely(!new_size))
142        return ZERO_SIZE_PTR;
143
144    return __do_krealloc(p, new_size, flags);
145
146}
147EXPORT_SYMBOL(__krealloc);
148
149/**
150 * krealloc - reallocate memory. The contents will remain unchanged.
151 * @p: object to reallocate memory for.
152 * @new_size: how many bytes of memory are required.
153 * @flags: the type of memory to allocate.
154 *
155 * The contents of the object pointed to are preserved up to the
156 * lesser of the new and old sizes. If @p is %NULL, krealloc()
157 * behaves exactly like kmalloc(). If @new_size is 0 and @p is not a
158 * %NULL pointer, the object pointed to is freed.
159 */
160void *krealloc(const void *p, size_t new_size, gfp_t flags)
161{
162    void *ret;
163
164    if (unlikely(!new_size)) {
165        kfree(p);
166        return ZERO_SIZE_PTR;
167    }
168
169    ret = __do_krealloc(p, new_size, flags);
170    if (ret && p != ret)
171        kfree(p);
172
173    return ret;
174}
175EXPORT_SYMBOL(krealloc);
176
177/**
178 * kzfree - like kfree but zero memory
179 * @p: object to free memory of
180 *
181 * The memory of the object @p points to is zeroed before freed.
182 * If @p is %NULL, kzfree() does nothing.
183 *
184 * Note: this function zeroes the whole allocated buffer which can be a good
185 * deal bigger than the requested buffer size passed to kmalloc(). So be
186 * careful when using this function in performance sensitive code.
187 */
188void kzfree(const void *p)
189{
190    size_t ks;
191    void *mem = (void *)p;
192
193    if (unlikely(ZERO_OR_NULL_PTR(mem)))
194        return;
195    ks = ksize(mem);
196    memset(mem, 0, ks);
197    kfree(mem);
198}
199EXPORT_SYMBOL(kzfree);
200
201/*
202 * strndup_user - duplicate an existing string from user space
203 * @s: The string to duplicate
204 * @n: Maximum number of bytes to copy, including the trailing NUL.
205 */
206char *strndup_user(const char __user *s, long n)
207{
208    char *p;
209    long length;
210
211    length = strnlen_user(s, n);
212
213    if (!length)
214        return ERR_PTR(-EFAULT);
215
216    if (length > n)
217        return ERR_PTR(-EINVAL);
218
219    p = memdup_user(s, length);
220
221    if (IS_ERR(p))
222        return p;
223
224    p[length - 1] = '\0';
225
226    return p;
227}
228EXPORT_SYMBOL(strndup_user);
229
230void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
231        struct vm_area_struct *prev, struct rb_node *rb_parent)
232{
233    struct vm_area_struct *next;
234
235    vma->vm_prev = prev;
236    if (prev) {
237        next = prev->vm_next;
238        prev->vm_next = vma;
239    } else {
240        mm->mmap = vma;
241        if (rb_parent)
242            next = rb_entry(rb_parent,
243                    struct vm_area_struct, vm_rb);
244        else
245            next = NULL;
246    }
247    vma->vm_next = next;
248    if (next)
249        next->vm_prev = vma;
250}
251
252/* Check if the vma is being used as a stack by this task */
253static int vm_is_stack_for_task(struct task_struct *t,
254                struct vm_area_struct *vma)
255{
256    return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
257}
258
259/*
260 * Check if the vma is being used as a stack.
261 * If is_group is non-zero, check in the entire thread group or else
262 * just check in the current task. Returns the pid of the task that
263 * the vma is stack for.
264 */
265pid_t vm_is_stack(struct task_struct *task,
266          struct vm_area_struct *vma, int in_group)
267{
268    pid_t ret = 0;
269
270    if (vm_is_stack_for_task(task, vma))
271        return task->pid;
272
273    if (in_group) {
274        struct task_struct *t;
275        rcu_read_lock();
276        if (!pid_alive(task))
277            goto done;
278
279        t = task;
280        do {
281            if (vm_is_stack_for_task(t, vma)) {
282                ret = t->pid;
283                goto done;
284            }
285        } while_each_thread(task, t);
286done:
287        rcu_read_unlock();
288    }
289
290    return ret;
291}
292
293#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
294void arch_pick_mmap_layout(struct mm_struct *mm)
295{
296    mm->mmap_base = TASK_UNMAPPED_BASE;
297    mm->get_unmapped_area = arch_get_unmapped_area;
298}
299#endif
300
301/*
302 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
303 * back to the regular GUP.
304 * If the architecture not support this function, simply return with no
305 * page pinned
306 */
307int __attribute__((weak)) __get_user_pages_fast(unsigned long start,
308                 int nr_pages, int write, struct page **pages)
309{
310    return 0;
311}
312EXPORT_SYMBOL_GPL(__get_user_pages_fast);
313
314/**
315 * get_user_pages_fast() - pin user pages in memory
316 * @start: starting user address
317 * @nr_pages: number of pages from start to pin
318 * @write: whether pages will be written to
319 * @pages: array that receives pointers to the pages pinned.
320 * Should be at least nr_pages long.
321 *
322 * Returns number of pages pinned. This may be fewer than the number
323 * requested. If nr_pages is 0 or negative, returns 0. If no pages
324 * were pinned, returns -errno.
325 *
326 * get_user_pages_fast provides equivalent functionality to get_user_pages,
327 * operating on current and current->mm, with force=0 and vma=NULL. However
328 * unlike get_user_pages, it must be called without mmap_sem held.
329 *
330 * get_user_pages_fast may take mmap_sem and page table locks, so no
331 * assumptions can be made about lack of locking. get_user_pages_fast is to be
332 * implemented in a way that is advantageous (vs get_user_pages()) when the
333 * user memory area is already faulted in and present in ptes. However if the
334 * pages have to be faulted in, it may turn out to be slightly slower so
335 * callers need to carefully consider what to use. On many architectures,
336 * get_user_pages_fast simply falls back to get_user_pages.
337 */
338int __attribute__((weak)) get_user_pages_fast(unsigned long start,
339                int nr_pages, int write, struct page **pages)
340{
341    struct mm_struct *mm = current->mm;
342    int ret;
343
344    down_read(&mm->mmap_sem);
345    ret = get_user_pages(current, mm, start, nr_pages,
346                    write, 0, pages, NULL);
347    up_read(&mm->mmap_sem);
348
349    return ret;
350}
351EXPORT_SYMBOL_GPL(get_user_pages_fast);
352
353unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
354    unsigned long len, unsigned long prot,
355    unsigned long flag, unsigned long pgoff)
356{
357    unsigned long ret;
358    struct mm_struct *mm = current->mm;
359    unsigned long populate;
360
361    ret = security_mmap_file(file, prot, flag);
362    if (!ret) {
363        down_write(&mm->mmap_sem);
364        ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
365                    &populate);
366        up_write(&mm->mmap_sem);
367        if (populate)
368            mm_populate(ret, populate);
369    }
370    return ret;
371}
372
373unsigned long vm_mmap(struct file *file, unsigned long addr,
374    unsigned long len, unsigned long prot,
375    unsigned long flag, unsigned long offset)
376{
377    if (unlikely(offset + PAGE_ALIGN(len) < offset))
378        return -EINVAL;
379    if (unlikely(offset & ~PAGE_MASK))
380        return -EINVAL;
381
382    return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
383}
384EXPORT_SYMBOL(vm_mmap);
385
386struct address_space *page_mapping(struct page *page)
387{
388    struct address_space *mapping = page->mapping;
389
390    VM_BUG_ON(PageSlab(page));
391    if (unlikely(PageSwapCache(page))) {
392        swp_entry_t entry;
393
394        entry.val = page_private(page);
395        mapping = swap_address_space(entry);
396    } else if ((unsigned long)mapping & PAGE_MAPPING_ANON)
397        mapping = NULL;
398    return mapping;
399}
400
401/* Tracepoints definitions. */
402EXPORT_TRACEPOINT_SYMBOL(kmalloc);
403EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
404EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
405EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
406EXPORT_TRACEPOINT_SYMBOL(kfree);
407EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
408

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive