Commit | Line | Data |
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4f18cd31 AV |
1 | #include <linux/export.h> |
2 | #include <linux/uio.h> | |
3 | #include <linux/pagemap.h> | |
91f79c43 AV |
4 | #include <linux/slab.h> |
5 | #include <linux/vmalloc.h> | |
4f18cd31 AV |
6 | |
7 | size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, | |
8 | struct iov_iter *i) | |
9 | { | |
10 | size_t skip, copy, left, wanted; | |
11 | const struct iovec *iov; | |
12 | char __user *buf; | |
13 | void *kaddr, *from; | |
14 | ||
15 | if (unlikely(bytes > i->count)) | |
16 | bytes = i->count; | |
17 | ||
18 | if (unlikely(!bytes)) | |
19 | return 0; | |
20 | ||
21 | wanted = bytes; | |
22 | iov = i->iov; | |
23 | skip = i->iov_offset; | |
24 | buf = iov->iov_base + skip; | |
25 | copy = min(bytes, iov->iov_len - skip); | |
26 | ||
27 | if (!fault_in_pages_writeable(buf, copy)) { | |
28 | kaddr = kmap_atomic(page); | |
29 | from = kaddr + offset; | |
30 | ||
31 | /* first chunk, usually the only one */ | |
32 | left = __copy_to_user_inatomic(buf, from, copy); | |
33 | copy -= left; | |
34 | skip += copy; | |
35 | from += copy; | |
36 | bytes -= copy; | |
37 | ||
38 | while (unlikely(!left && bytes)) { | |
39 | iov++; | |
40 | buf = iov->iov_base; | |
41 | copy = min(bytes, iov->iov_len); | |
42 | left = __copy_to_user_inatomic(buf, from, copy); | |
43 | copy -= left; | |
44 | skip = copy; | |
45 | from += copy; | |
46 | bytes -= copy; | |
47 | } | |
48 | if (likely(!bytes)) { | |
49 | kunmap_atomic(kaddr); | |
50 | goto done; | |
51 | } | |
52 | offset = from - kaddr; | |
53 | buf += copy; | |
54 | kunmap_atomic(kaddr); | |
55 | copy = min(bytes, iov->iov_len - skip); | |
56 | } | |
57 | /* Too bad - revert to non-atomic kmap */ | |
58 | kaddr = kmap(page); | |
59 | from = kaddr + offset; | |
60 | left = __copy_to_user(buf, from, copy); | |
61 | copy -= left; | |
62 | skip += copy; | |
63 | from += copy; | |
64 | bytes -= copy; | |
65 | while (unlikely(!left && bytes)) { | |
66 | iov++; | |
67 | buf = iov->iov_base; | |
68 | copy = min(bytes, iov->iov_len); | |
69 | left = __copy_to_user(buf, from, copy); | |
70 | copy -= left; | |
71 | skip = copy; | |
72 | from += copy; | |
73 | bytes -= copy; | |
74 | } | |
75 | kunmap(page); | |
76 | done: | |
77 | i->count -= wanted - bytes; | |
78 | i->nr_segs -= iov - i->iov; | |
79 | i->iov = iov; | |
80 | i->iov_offset = skip; | |
81 | return wanted - bytes; | |
82 | } | |
83 | EXPORT_SYMBOL(copy_page_to_iter); | |
84 | ||
85 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, | |
86 | const struct iovec *iov, size_t base, size_t bytes) | |
87 | { | |
88 | size_t copied = 0, left = 0; | |
89 | ||
90 | while (bytes) { | |
91 | char __user *buf = iov->iov_base + base; | |
92 | int copy = min(bytes, iov->iov_len - base); | |
93 | ||
94 | base = 0; | |
95 | left = __copy_from_user_inatomic(vaddr, buf, copy); | |
96 | copied += copy; | |
97 | bytes -= copy; | |
98 | vaddr += copy; | |
99 | iov++; | |
100 | ||
101 | if (unlikely(left)) | |
102 | break; | |
103 | } | |
104 | return copied - left; | |
105 | } | |
106 | ||
107 | /* | |
108 | * Copy as much as we can into the page and return the number of bytes which | |
109 | * were successfully copied. If a fault is encountered then return the number of | |
110 | * bytes which were copied. | |
111 | */ | |
112 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
113 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
114 | { | |
115 | char *kaddr; | |
116 | size_t copied; | |
117 | ||
118 | kaddr = kmap_atomic(page); | |
119 | if (likely(i->nr_segs == 1)) { | |
120 | int left; | |
121 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
122 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); | |
123 | copied = bytes - left; | |
124 | } else { | |
125 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
126 | i->iov, i->iov_offset, bytes); | |
127 | } | |
128 | kunmap_atomic(kaddr); | |
129 | ||
130 | return copied; | |
131 | } | |
132 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); | |
133 | ||
4f18cd31 AV |
134 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
135 | { | |
136 | BUG_ON(i->count < bytes); | |
137 | ||
138 | if (likely(i->nr_segs == 1)) { | |
139 | i->iov_offset += bytes; | |
140 | i->count -= bytes; | |
141 | } else { | |
142 | const struct iovec *iov = i->iov; | |
143 | size_t base = i->iov_offset; | |
144 | unsigned long nr_segs = i->nr_segs; | |
145 | ||
146 | /* | |
147 | * The !iov->iov_len check ensures we skip over unlikely | |
148 | * zero-length segments (without overruning the iovec). | |
149 | */ | |
150 | while (bytes || unlikely(i->count && !iov->iov_len)) { | |
151 | int copy; | |
152 | ||
153 | copy = min(bytes, iov->iov_len - base); | |
154 | BUG_ON(!i->count || i->count < copy); | |
155 | i->count -= copy; | |
156 | bytes -= copy; | |
157 | base += copy; | |
158 | if (iov->iov_len == base) { | |
159 | iov++; | |
160 | nr_segs--; | |
161 | base = 0; | |
162 | } | |
163 | } | |
164 | i->iov = iov; | |
165 | i->iov_offset = base; | |
166 | i->nr_segs = nr_segs; | |
167 | } | |
168 | } | |
169 | EXPORT_SYMBOL(iov_iter_advance); | |
170 | ||
171 | /* | |
172 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
173 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
174 | * accessed (ie. because it is an invalid address). | |
175 | * | |
176 | * writev-intensive code may want this to prefault several iovecs -- that | |
177 | * would be possible (callers must not rely on the fact that _only_ the | |
178 | * first iovec will be faulted with the current implementation). | |
179 | */ | |
180 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
181 | { | |
182 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
183 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); | |
184 | return fault_in_pages_readable(buf, bytes); | |
185 | } | |
186 | EXPORT_SYMBOL(iov_iter_fault_in_readable); | |
187 | ||
188 | /* | |
189 | * Return the count of just the current iov_iter segment. | |
190 | */ | |
191 | size_t iov_iter_single_seg_count(const struct iov_iter *i) | |
192 | { | |
193 | const struct iovec *iov = i->iov; | |
194 | if (i->nr_segs == 1) | |
195 | return i->count; | |
196 | else | |
197 | return min(i->count, iov->iov_len - i->iov_offset); | |
198 | } | |
199 | EXPORT_SYMBOL(iov_iter_single_seg_count); | |
886a3911 AV |
200 | |
201 | unsigned long iov_iter_alignment(const struct iov_iter *i) | |
202 | { | |
203 | const struct iovec *iov = i->iov; | |
204 | unsigned long res; | |
205 | size_t size = i->count; | |
206 | size_t n; | |
207 | ||
208 | if (!size) | |
209 | return 0; | |
210 | ||
211 | res = (unsigned long)iov->iov_base + i->iov_offset; | |
212 | n = iov->iov_len - i->iov_offset; | |
213 | if (n >= size) | |
214 | return res | size; | |
215 | size -= n; | |
216 | res |= n; | |
217 | while (size > (++iov)->iov_len) { | |
218 | res |= (unsigned long)iov->iov_base | iov->iov_len; | |
219 | size -= iov->iov_len; | |
220 | } | |
221 | res |= (unsigned long)iov->iov_base | size; | |
222 | return res; | |
223 | } | |
224 | EXPORT_SYMBOL(iov_iter_alignment); | |
71d8e532 AV |
225 | |
226 | void iov_iter_init(struct iov_iter *i, int direction, | |
227 | const struct iovec *iov, unsigned long nr_segs, | |
228 | size_t count) | |
229 | { | |
230 | /* It will get better. Eventually... */ | |
231 | if (segment_eq(get_fs(), KERNEL_DS)) | |
232 | direction |= REQ_KERNEL; | |
233 | i->type = direction; | |
234 | i->iov = iov; | |
235 | i->nr_segs = nr_segs; | |
236 | i->iov_offset = 0; | |
237 | i->count = count; | |
238 | } | |
239 | EXPORT_SYMBOL(iov_iter_init); | |
7b2c99d1 AV |
240 | |
241 | ssize_t iov_iter_get_pages(struct iov_iter *i, | |
242 | struct page **pages, size_t maxsize, | |
243 | size_t *start) | |
244 | { | |
245 | size_t offset = i->iov_offset; | |
246 | const struct iovec *iov = i->iov; | |
247 | size_t len; | |
248 | unsigned long addr; | |
249 | int n; | |
250 | int res; | |
251 | ||
252 | len = iov->iov_len - offset; | |
253 | if (len > i->count) | |
254 | len = i->count; | |
255 | if (len > maxsize) | |
256 | len = maxsize; | |
257 | addr = (unsigned long)iov->iov_base + offset; | |
258 | len += *start = addr & (PAGE_SIZE - 1); | |
259 | addr &= ~(PAGE_SIZE - 1); | |
260 | n = (len + PAGE_SIZE - 1) / PAGE_SIZE; | |
261 | res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages); | |
262 | if (unlikely(res < 0)) | |
263 | return res; | |
264 | return (res == n ? len : res * PAGE_SIZE) - *start; | |
265 | } | |
266 | EXPORT_SYMBOL(iov_iter_get_pages); | |
f67da30c | 267 | |
91f79c43 AV |
268 | ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, |
269 | struct page ***pages, size_t maxsize, | |
270 | size_t *start) | |
271 | { | |
272 | size_t offset = i->iov_offset; | |
273 | const struct iovec *iov = i->iov; | |
274 | size_t len; | |
275 | unsigned long addr; | |
276 | void *p; | |
277 | int n; | |
278 | int res; | |
279 | ||
280 | len = iov->iov_len - offset; | |
281 | if (len > i->count) | |
282 | len = i->count; | |
283 | if (len > maxsize) | |
284 | len = maxsize; | |
285 | addr = (unsigned long)iov->iov_base + offset; | |
286 | len += *start = addr & (PAGE_SIZE - 1); | |
287 | addr &= ~(PAGE_SIZE - 1); | |
288 | n = (len + PAGE_SIZE - 1) / PAGE_SIZE; | |
289 | ||
290 | p = kmalloc(n * sizeof(struct page *), GFP_KERNEL); | |
291 | if (!p) | |
292 | p = vmalloc(n * sizeof(struct page *)); | |
293 | if (!p) | |
294 | return -ENOMEM; | |
295 | ||
296 | res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p); | |
297 | if (unlikely(res < 0)) { | |
298 | kvfree(p); | |
299 | return res; | |
300 | } | |
301 | *pages = p; | |
302 | return (res == n ? len : res * PAGE_SIZE) - *start; | |
303 | } | |
304 | EXPORT_SYMBOL(iov_iter_get_pages_alloc); | |
305 | ||
f67da30c AV |
306 | int iov_iter_npages(const struct iov_iter *i, int maxpages) |
307 | { | |
308 | size_t offset = i->iov_offset; | |
309 | size_t size = i->count; | |
310 | const struct iovec *iov = i->iov; | |
311 | int npages = 0; | |
312 | int n; | |
313 | ||
314 | for (n = 0; size && n < i->nr_segs; n++, iov++) { | |
315 | unsigned long addr = (unsigned long)iov->iov_base + offset; | |
316 | size_t len = iov->iov_len - offset; | |
317 | offset = 0; | |
318 | if (unlikely(!len)) /* empty segment */ | |
319 | continue; | |
320 | if (len > size) | |
321 | len = size; | |
322 | npages += (addr + len + PAGE_SIZE - 1) / PAGE_SIZE | |
323 | - addr / PAGE_SIZE; | |
324 | if (npages >= maxpages) /* don't bother going further */ | |
325 | return maxpages; | |
326 | size -= len; | |
327 | offset = 0; | |
328 | } | |
329 | return min(npages, maxpages); | |
330 | } | |
331 | EXPORT_SYMBOL(iov_iter_npages); |