1 #include <linux/mm.h> 2 #include <linux/slab.h> 3 #include <linux/string.h> 4 #include <linux/module.h> 5 #include <linux/err.h> 6 #include <linux/sched.h> 7 #include <asm/uaccess.h> 8 9 #define CREATE_TRACE_POINTS 10 #include <trace/events/kmem.h> 11 12 /** 13 * kstrdup - allocate space for and copy an existing string 14 * @s: the string to duplicate 15 * @gfp: the GFP mask used in the kmalloc() call when allocating memory 16 */ 17 char *kstrdup(const char *s, gfp_t gfp) 18 { 19 size_t len; 20 char *buf; 21 22 if (!s) 23 return NULL; 24 25 len = strlen(s) + 1; 26 buf = kmalloc_track_caller(len, gfp); 27 if (buf) 28 memcpy(buf, s, len); 29 return buf; 30 } 31 EXPORT_SYMBOL(kstrdup); 32 33 /** 34 * kstrndup - allocate space for and copy an existing string 35 * @s: the string to duplicate 36 * @max: read at most @max chars from @s 37 * @gfp: the GFP mask used in the kmalloc() call when allocating memory 38 */ 39 char *kstrndup(const char *s, size_t max, gfp_t gfp) 40 { 41 size_t len; 42 char *buf; 43 44 if (!s) 45 return NULL; 46 47 len = strnlen(s, max); 48 buf = kmalloc_track_caller(len+1, gfp); 49 if (buf) { 50 memcpy(buf, s, len); 51 buf[len] = '\0'; 52 } 53 return buf; 54 } 55 EXPORT_SYMBOL(kstrndup); 56 57 /** 58 * kmemdup - duplicate region of memory 59 * 60 * @src: memory region to duplicate 61 * @len: memory region length 62 * @gfp: GFP mask to use 63 */ 64 void *kmemdup(const void *src, size_t len, gfp_t gfp) 65 { 66 void *p; 67 68 p = kmalloc_track_caller(len, gfp); 69 if (p) 70 memcpy(p, src, len); 71 return p; 72 } 73 EXPORT_SYMBOL(kmemdup); 74 75 /** 76 * memdup_user - duplicate memory region from user space 77 * 78 * @src: source address in user space 79 * @len: number of bytes to copy 80 * 81 * Returns an ERR_PTR() on failure. 82 */ 83 void *memdup_user(const void __user *src, size_t len) 84 { 85 void *p; 86 87 /* 88 * Always use GFP_KERNEL, since copy_from_user() can sleep and 89 * cause pagefault, which makes it pointless to use GFP_NOFS 90 * or GFP_ATOMIC. 91 */ 92 p = kmalloc_track_caller(len, GFP_KERNEL); 93 if (!p) 94 return ERR_PTR(-ENOMEM); 95 96 if (copy_from_user(p, src, len)) { 97 kfree(p); 98 return ERR_PTR(-EFAULT); 99 } 100 101 return p; 102 } 103 EXPORT_SYMBOL(memdup_user); 104 105 /** 106 * __krealloc - like krealloc() but don't free @p. 107 * @p: object to reallocate memory for. 108 * @new_size: how many bytes of memory are required. 109 * @flags: the type of memory to allocate. 110 * 111 * This function is like krealloc() except it never frees the originally 112 * allocated buffer. Use this if you don't want to free the buffer immediately 113 * like, for example, with RCU. 114 */ 115 void *__krealloc(const void *p, size_t new_size, gfp_t flags) 116 { 117 void *ret; 118 size_t ks = 0; 119 120 if (unlikely(!new_size)) 121 return ZERO_SIZE_PTR; 122 123 if (p) 124 ks = ksize(p); 125 126 if (ks >= new_size) 127 return (void *)p; 128 129 ret = kmalloc_track_caller(new_size, flags); 130 if (ret && p) 131 memcpy(ret, p, ks); 132 133 return ret; 134 } 135 EXPORT_SYMBOL(__krealloc); 136 137 /** 138 * krealloc - reallocate memory. The contents will remain unchanged. 139 * @p: object to reallocate memory for. 140 * @new_size: how many bytes of memory are required. 141 * @flags: the type of memory to allocate. 142 * 143 * The contents of the object pointed to are preserved up to the 144 * lesser of the new and old sizes. If @p is %NULL, krealloc() 145 * behaves exactly like kmalloc(). If @size is 0 and @p is not a 146 * %NULL pointer, the object pointed to is freed. 147 */ 148 void *krealloc(const void *p, size_t new_size, gfp_t flags) 149 { 150 void *ret; 151 152 if (unlikely(!new_size)) { 153 kfree(p); 154 return ZERO_SIZE_PTR; 155 } 156 157 ret = __krealloc(p, new_size, flags); 158 if (ret && p != ret) 159 kfree(p); 160 161 return ret; 162 } 163 EXPORT_SYMBOL(krealloc); 164 165 /** 166 * kzfree - like kfree but zero memory 167 * @p: object to free memory of 168 * 169 * The memory of the object @p points to is zeroed before freed. 170 * If @p is %NULL, kzfree() does nothing. 171 * 172 * Note: this function zeroes the whole allocated buffer which can be a good 173 * deal bigger than the requested buffer size passed to kmalloc(). So be 174 * careful when using this function in performance sensitive code. 175 */ 176 void kzfree(const void *p) 177 { 178 size_t ks; 179 void *mem = (void *)p; 180 181 if (unlikely(ZERO_OR_NULL_PTR(mem))) 182 return; 183 ks = ksize(mem); 184 memset(mem, 0, ks); 185 kfree(mem); 186 } 187 EXPORT_SYMBOL(kzfree); 188 189 /* 190 * strndup_user - duplicate an existing string from user space 191 * @s: The string to duplicate 192 * @n: Maximum number of bytes to copy, including the trailing NUL. 193 */ 194 char *strndup_user(const char __user *s, long n) 195 { 196 char *p; 197 long length; 198 199 length = strnlen_user(s, n); 200 201 if (!length) 202 return ERR_PTR(-EFAULT); 203 204 if (length > n) 205 return ERR_PTR(-EINVAL); 206 207 p = memdup_user(s, length); 208 209 if (IS_ERR(p)) 210 return p; 211 212 p[length - 1] = '\0'; 213 214 return p; 215 } 216 EXPORT_SYMBOL(strndup_user); 217 218 #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) 219 void arch_pick_mmap_layout(struct mm_struct *mm) 220 { 221 mm->mmap_base = TASK_UNMAPPED_BASE; 222 mm->get_unmapped_area = arch_get_unmapped_area; 223 mm->unmap_area = arch_unmap_area; 224 } 225 #endif 226 227 /* 228 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall 229 * back to the regular GUP. 230 * If the architecture not support this function, simply return with no 231 * page pinned 232 */ 233 int __attribute__((weak)) __get_user_pages_fast(unsigned long start, 234 int nr_pages, int write, struct page **pages) 235 { 236 return 0; 237 } 238 EXPORT_SYMBOL_GPL(__get_user_pages_fast); 239 240 /** 241 * get_user_pages_fast() - pin user pages in memory 242 * @start: starting user address 243 * @nr_pages: number of pages from start to pin 244 * @write: whether pages will be written to 245 * @pages: array that receives pointers to the pages pinned. 246 * Should be at least nr_pages long. 247 * 248 * Returns number of pages pinned. This may be fewer than the number 249 * requested. If nr_pages is 0 or negative, returns 0. If no pages 250 * were pinned, returns -errno. 251 * 252 * get_user_pages_fast provides equivalent functionality to get_user_pages, 253 * operating on current and current->mm, with force=0 and vma=NULL. However 254 * unlike get_user_pages, it must be called without mmap_sem held. 255 * 256 * get_user_pages_fast may take mmap_sem and page table locks, so no 257 * assumptions can be made about lack of locking. get_user_pages_fast is to be 258 * implemented in a way that is advantageous (vs get_user_pages()) when the 259 * user memory area is already faulted in and present in ptes. However if the 260 * pages have to be faulted in, it may turn out to be slightly slower so 261 * callers need to carefully consider what to use. On many architectures, 262 * get_user_pages_fast simply falls back to get_user_pages. 263 */ 264 int __attribute__((weak)) get_user_pages_fast(unsigned long start, 265 int nr_pages, int write, struct page **pages) 266 { 267 struct mm_struct *mm = current->mm; 268 int ret; 269 270 down_read(&mm->mmap_sem); 271 ret = get_user_pages(current, mm, start, nr_pages, 272 write, 0, pages, NULL); 273 up_read(&mm->mmap_sem); 274 275 return ret; 276 } 277 EXPORT_SYMBOL_GPL(get_user_pages_fast); 278 279 /* Tracepoints definitions. */ 280 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 281 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 282 EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); 283 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); 284 EXPORT_TRACEPOINT_SYMBOL(kfree); 285 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 286