1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 4 */ 5 6 #include <linux/err.h> 7 #include <linux/highmem.h> 8 #include <linux/mm.h> 9 #include <linux/module.h> 10 #include <linux/sched.h> 11 #include <asm/current.h> 12 #include <asm/page.h> 13 #include <kern_util.h> 14 #include <asm/futex.h> 15 #include <os.h> 16 17 pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr) 18 { 19 pgd_t *pgd; 20 p4d_t *p4d; 21 pud_t *pud; 22 pmd_t *pmd; 23 24 if (mm == NULL) 25 return NULL; 26 27 pgd = pgd_offset(mm, addr); 28 if (!pgd_present(*pgd)) 29 return NULL; 30 31 p4d = p4d_offset(pgd, addr); 32 if (!p4d_present(*p4d)) 33 return NULL; 34 35 pud = pud_offset(p4d, addr); 36 if (!pud_present(*pud)) 37 return NULL; 38 39 pmd = pmd_offset(pud, addr); 40 if (!pmd_present(*pmd)) 41 return NULL; 42 43 return pte_offset_kernel(pmd, addr); 44 } 45 46 static pte_t *maybe_map(unsigned long virt, int is_write) 47 { 48 pte_t *pte = virt_to_pte(current->mm, virt); 49 int err, dummy_code; 50 51 if ((pte == NULL) || !pte_present(*pte) || 52 (is_write && !pte_write(*pte))) { 53 err = handle_page_fault(virt, 0, is_write, 1, &dummy_code); 54 if (err) 55 return NULL; 56 pte = virt_to_pte(current->mm, virt); 57 } 58 if (!pte_present(*pte)) 59 pte = NULL; 60 61 return pte; 62 } 63 64 static int do_op_one_page(unsigned long addr, int len, int is_write, 65 int (*op)(unsigned long addr, int len, void *arg), void *arg) 66 { 67 struct page *page; 68 pte_t *pte; 69 int n; 70 71 pte = maybe_map(addr, is_write); 72 if (pte == NULL) 73 return -1; 74 75 page = pte_page(*pte); 76 #ifdef CONFIG_64BIT 77 pagefault_disable(); 78 addr = (unsigned long) page_address(page) + 79 (addr & ~PAGE_MASK); 80 #else 81 addr = (unsigned long) kmap_atomic(page) + 82 (addr & ~PAGE_MASK); 83 #endif 84 n = (*op)(addr, len, arg); 85 86 #ifdef CONFIG_64BIT 87 pagefault_enable(); 88 #else 89 kunmap_atomic((void *)addr); 90 #endif 91 92 return n; 93 } 94 95 static long buffer_op(unsigned long addr, int len, int is_write, 96 int (*op)(unsigned long, int, void *), void *arg) 97 { 98 long size, remain, n; 99 100 size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len); 101 remain = len; 102 103 n = do_op_one_page(addr, size, is_write, op, arg); 104 if (n != 0) { 105 remain = (n < 0 ? remain : 0); 106 goto out; 107 } 108 109 addr += size; 110 remain -= size; 111 if (remain == 0) 112 goto out; 113 114 while (addr < ((addr + remain) & PAGE_MASK)) { 115 n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg); 116 if (n != 0) { 117 remain = (n < 0 ? remain : 0); 118 goto out; 119 } 120 121 addr += PAGE_SIZE; 122 remain -= PAGE_SIZE; 123 } 124 if (remain == 0) 125 goto out; 126 127 n = do_op_one_page(addr, remain, is_write, op, arg); 128 if (n != 0) { 129 remain = (n < 0 ? remain : 0); 130 goto out; 131 } 132 133 return 0; 134 out: 135 return remain; 136 } 137 138 static int copy_chunk_from_user(unsigned long from, int len, void *arg) 139 { 140 unsigned long *to_ptr = arg, to = *to_ptr; 141 142 memcpy((void *) to, (void *) from, len); 143 *to_ptr += len; 144 return 0; 145 } 146 147 unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n) 148 { 149 return buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to); 150 } 151 EXPORT_SYMBOL(raw_copy_from_user); 152 153 static int copy_chunk_to_user(unsigned long to, int len, void *arg) 154 { 155 unsigned long *from_ptr = arg, from = *from_ptr; 156 157 memcpy((void *) to, (void *) from, len); 158 *from_ptr += len; 159 return 0; 160 } 161 162 unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n) 163 { 164 return buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from); 165 } 166 EXPORT_SYMBOL(raw_copy_to_user); 167 168 static int strncpy_chunk_from_user(unsigned long from, int len, void *arg) 169 { 170 char **to_ptr = arg, *to = *to_ptr; 171 int n; 172 173 strncpy(to, (void *) from, len); 174 n = strnlen(to, len); 175 *to_ptr += n; 176 177 if (n < len) 178 return 1; 179 return 0; 180 } 181 182 long strncpy_from_user(char *dst, const char __user *src, long count) 183 { 184 long n; 185 char *ptr = dst; 186 187 if (!access_ok(src, 1)) 188 return -EFAULT; 189 n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user, 190 &ptr); 191 if (n != 0) 192 return -EFAULT; 193 return strnlen(dst, count); 194 } 195 EXPORT_SYMBOL(strncpy_from_user); 196 197 static int clear_chunk(unsigned long addr, int len, void *unused) 198 { 199 memset((void *) addr, 0, len); 200 return 0; 201 } 202 203 unsigned long __clear_user(void __user *mem, unsigned long len) 204 { 205 return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL); 206 } 207 EXPORT_SYMBOL(__clear_user); 208 209 static int strnlen_chunk(unsigned long str, int len, void *arg) 210 { 211 int *len_ptr = arg, n; 212 213 n = strnlen((void *) str, len); 214 *len_ptr += n; 215 216 if (n < len) 217 return 1; 218 return 0; 219 } 220 221 long strnlen_user(const char __user *str, long len) 222 { 223 int count = 0, n; 224 225 if (!access_ok(str, 1)) 226 return -EFAULT; 227 n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count); 228 if (n == 0) 229 return count + 1; 230 return 0; 231 } 232 EXPORT_SYMBOL(strnlen_user); 233 234 /** 235 * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant 236 * argument and comparison of the previous 237 * futex value with another constant. 238 * 239 * @encoded_op: encoded operation to execute 240 * @uaddr: pointer to user space address 241 * 242 * Return: 243 * 0 - On success 244 * -EFAULT - User access resulted in a page fault 245 * -EAGAIN - Atomic operation was unable to complete due to contention 246 * -ENOSYS - Operation not supported 247 */ 248 249 int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr) 250 { 251 int oldval, ret; 252 struct page *page; 253 unsigned long addr = (unsigned long) uaddr; 254 pte_t *pte; 255 256 ret = -EFAULT; 257 if (!access_ok(uaddr, sizeof(*uaddr))) 258 return -EFAULT; 259 preempt_disable(); 260 pte = maybe_map(addr, 1); 261 if (pte == NULL) 262 goto out_inuser; 263 264 page = pte_page(*pte); 265 #ifdef CONFIG_64BIT 266 pagefault_disable(); 267 addr = (unsigned long) page_address(page) + 268 (((unsigned long) addr) & ~PAGE_MASK); 269 #else 270 addr = (unsigned long) kmap_atomic(page) + 271 ((unsigned long) addr & ~PAGE_MASK); 272 #endif 273 uaddr = (u32 *) addr; 274 oldval = *uaddr; 275 276 ret = 0; 277 278 switch (op) { 279 case FUTEX_OP_SET: 280 *uaddr = oparg; 281 break; 282 case FUTEX_OP_ADD: 283 *uaddr += oparg; 284 break; 285 case FUTEX_OP_OR: 286 *uaddr |= oparg; 287 break; 288 case FUTEX_OP_ANDN: 289 *uaddr &= ~oparg; 290 break; 291 case FUTEX_OP_XOR: 292 *uaddr ^= oparg; 293 break; 294 default: 295 ret = -ENOSYS; 296 } 297 #ifdef CONFIG_64BIT 298 pagefault_enable(); 299 #else 300 kunmap_atomic((void *)addr); 301 #endif 302 303 out_inuser: 304 preempt_enable(); 305 306 if (ret == 0) 307 *oval = oldval; 308 309 return ret; 310 } 311 EXPORT_SYMBOL(arch_futex_atomic_op_inuser); 312 313 /** 314 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the 315 * uaddr with newval if the current value is 316 * oldval. 317 * @uval: pointer to store content of @uaddr 318 * @uaddr: pointer to user space address 319 * @oldval: old value 320 * @newval: new value to store to @uaddr 321 * 322 * Return: 323 * 0 - On success 324 * -EFAULT - User access resulted in a page fault 325 * -EAGAIN - Atomic operation was unable to complete due to contention 326 */ 327 328 int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, 329 u32 oldval, u32 newval) 330 { 331 struct page *page; 332 pte_t *pte; 333 int ret = -EFAULT; 334 335 if (!access_ok(uaddr, sizeof(*uaddr))) 336 return -EFAULT; 337 338 preempt_disable(); 339 pte = maybe_map((unsigned long) uaddr, 1); 340 if (pte == NULL) 341 goto out_inatomic; 342 343 page = pte_page(*pte); 344 #ifdef CONFIG_64BIT 345 pagefault_disable(); 346 uaddr = page_address(page) + (((unsigned long) uaddr) & ~PAGE_MASK); 347 #else 348 uaddr = kmap_atomic(page) + ((unsigned long) uaddr & ~PAGE_MASK); 349 #endif 350 351 *uval = *uaddr; 352 353 ret = cmpxchg(uaddr, oldval, newval); 354 355 #ifdef CONFIG_64BIT 356 pagefault_enable(); 357 #else 358 kunmap_atomic(uaddr); 359 #endif 360 ret = 0; 361 362 out_inatomic: 363 preempt_enable(); 364 return ret; 365 } 366 EXPORT_SYMBOL(futex_atomic_cmpxchg_inatomic); 367