1 /* 2 * Copyright (C) 2012 Regents of the University of California 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation, version 2. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 * 13 * This file was copied from include/asm-generic/uaccess.h 14 */ 15 16 #ifndef _ASM_RISCV_UACCESS_H 17 #define _ASM_RISCV_UACCESS_H 18 19 /* 20 * User space memory access functions 21 */ 22 #include <linux/errno.h> 23 #include <linux/compiler.h> 24 #include <linux/thread_info.h> 25 #include <asm/byteorder.h> 26 #include <asm/extable.h> 27 #include <asm/asm.h> 28 29 #define __enable_user_access() \ 30 __asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory") 31 #define __disable_user_access() \ 32 __asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory") 33 34 /* 35 * The fs value determines whether argument validity checking should be 36 * performed or not. If get_fs() == USER_DS, checking is performed, with 37 * get_fs() == KERNEL_DS, checking is bypassed. 38 * 39 * For historical reasons, these macros are grossly misnamed. 40 */ 41 42 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) 43 44 #define KERNEL_DS MAKE_MM_SEG(~0UL) 45 #define USER_DS MAKE_MM_SEG(TASK_SIZE) 46 47 #define get_fs() (current_thread_info()->addr_limit) 48 49 static inline void set_fs(mm_segment_t fs) 50 { 51 current_thread_info()->addr_limit = fs; 52 } 53 54 #define segment_eq(a, b) ((a).seg == (b).seg) 55 56 #define user_addr_max() (get_fs().seg) 57 58 59 /** 60 * access_ok: - Checks if a user space pointer is valid 61 * @addr: User space pointer to start of block to check 62 * @size: Size of block to check 63 * 64 * Context: User context only. This function may sleep. 65 * 66 * Checks if a pointer to a block of memory in user space is valid. 67 * 68 * Returns true (nonzero) if the memory block may be valid, false (zero) 69 * if it is definitely invalid. 70 * 71 * Note that, depending on architecture, this function probably just 72 * checks that the pointer is in the user space range - after calling 73 * this function, memory access functions may still return -EFAULT. 74 */ 75 #define access_ok(addr, size) ({ \ 76 __chk_user_ptr(addr); \ 77 likely(__access_ok((unsigned long __force)(addr), (size))); \ 78 }) 79 80 /* 81 * Ensure that the range [addr, addr+size) is within the process's 82 * address space 83 */ 84 static inline int __access_ok(unsigned long addr, unsigned long size) 85 { 86 const mm_segment_t fs = get_fs(); 87 88 return size <= fs.seg && addr <= fs.seg - size; 89 } 90 91 /* 92 * The exception table consists of pairs of addresses: the first is the 93 * address of an instruction that is allowed to fault, and the second is 94 * the address at which the program should continue. No registers are 95 * modified, so it is entirely up to the continuation code to figure out 96 * what to do. 97 * 98 * All the routines below use bits of fixup code that are out of line 99 * with the main instruction path. This means when everything is well, 100 * we don't even have to jump over them. Further, they do not intrude 101 * on our cache or tlb entries. 102 */ 103 104 #define __LSW 0 105 #define __MSW 1 106 107 /* 108 * The "__xxx" versions of the user access functions do not verify the address 109 * space - it must have been done previously with a separate "access_ok()" 110 * call. 111 */ 112 113 #define __get_user_asm(insn, x, ptr, err) \ 114 do { \ 115 uintptr_t __tmp; \ 116 __typeof__(x) __x; \ 117 __enable_user_access(); \ 118 __asm__ __volatile__ ( \ 119 "1:\n" \ 120 " " insn " %1, %3\n" \ 121 "2:\n" \ 122 " .section .fixup,\"ax\"\n" \ 123 " .balign 4\n" \ 124 "3:\n" \ 125 " li %0, %4\n" \ 126 " li %1, 0\n" \ 127 " jump 2b, %2\n" \ 128 " .previous\n" \ 129 " .section __ex_table,\"a\"\n" \ 130 " .balign " RISCV_SZPTR "\n" \ 131 " " RISCV_PTR " 1b, 3b\n" \ 132 " .previous" \ 133 : "+r" (err), "=&r" (__x), "=r" (__tmp) \ 134 : "m" (*(ptr)), "i" (-EFAULT)); \ 135 __disable_user_access(); \ 136 (x) = __x; \ 137 } while (0) 138 139 #ifdef CONFIG_64BIT 140 #define __get_user_8(x, ptr, err) \ 141 __get_user_asm("ld", x, ptr, err) 142 #else /* !CONFIG_64BIT */ 143 #define __get_user_8(x, ptr, err) \ 144 do { \ 145 u32 __user *__ptr = (u32 __user *)(ptr); \ 146 u32 __lo, __hi; \ 147 uintptr_t __tmp; \ 148 __enable_user_access(); \ 149 __asm__ __volatile__ ( \ 150 "1:\n" \ 151 " lw %1, %4\n" \ 152 "2:\n" \ 153 " lw %2, %5\n" \ 154 "3:\n" \ 155 " .section .fixup,\"ax\"\n" \ 156 " .balign 4\n" \ 157 "4:\n" \ 158 " li %0, %6\n" \ 159 " li %1, 0\n" \ 160 " li %2, 0\n" \ 161 " jump 3b, %3\n" \ 162 " .previous\n" \ 163 " .section __ex_table,\"a\"\n" \ 164 " .balign " RISCV_SZPTR "\n" \ 165 " " RISCV_PTR " 1b, 4b\n" \ 166 " " RISCV_PTR " 2b, 4b\n" \ 167 " .previous" \ 168 : "+r" (err), "=&r" (__lo), "=r" (__hi), \ 169 "=r" (__tmp) \ 170 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]), \ 171 "i" (-EFAULT)); \ 172 __disable_user_access(); \ 173 (x) = (__typeof__(x))((__typeof__((x)-(x)))( \ 174 (((u64)__hi << 32) | __lo))); \ 175 } while (0) 176 #endif /* CONFIG_64BIT */ 177 178 179 /** 180 * __get_user: - Get a simple variable from user space, with less checking. 181 * @x: Variable to store result. 182 * @ptr: Source address, in user space. 183 * 184 * Context: User context only. This function may sleep. 185 * 186 * This macro copies a single simple variable from user space to kernel 187 * space. It supports simple types like char and int, but not larger 188 * data types like structures or arrays. 189 * 190 * @ptr must have pointer-to-simple-variable type, and the result of 191 * dereferencing @ptr must be assignable to @x without a cast. 192 * 193 * Caller must check the pointer with access_ok() before calling this 194 * function. 195 * 196 * Returns zero on success, or -EFAULT on error. 197 * On error, the variable @x is set to zero. 198 */ 199 #define __get_user(x, ptr) \ 200 ({ \ 201 register long __gu_err = 0; \ 202 const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 203 __chk_user_ptr(__gu_ptr); \ 204 switch (sizeof(*__gu_ptr)) { \ 205 case 1: \ 206 __get_user_asm("lb", (x), __gu_ptr, __gu_err); \ 207 break; \ 208 case 2: \ 209 __get_user_asm("lh", (x), __gu_ptr, __gu_err); \ 210 break; \ 211 case 4: \ 212 __get_user_asm("lw", (x), __gu_ptr, __gu_err); \ 213 break; \ 214 case 8: \ 215 __get_user_8((x), __gu_ptr, __gu_err); \ 216 break; \ 217 default: \ 218 BUILD_BUG(); \ 219 } \ 220 __gu_err; \ 221 }) 222 223 /** 224 * get_user: - Get a simple variable from user space. 225 * @x: Variable to store result. 226 * @ptr: Source address, in user space. 227 * 228 * Context: User context only. This function may sleep. 229 * 230 * This macro copies a single simple variable from user space to kernel 231 * space. It supports simple types like char and int, but not larger 232 * data types like structures or arrays. 233 * 234 * @ptr must have pointer-to-simple-variable type, and the result of 235 * dereferencing @ptr must be assignable to @x without a cast. 236 * 237 * Returns zero on success, or -EFAULT on error. 238 * On error, the variable @x is set to zero. 239 */ 240 #define get_user(x, ptr) \ 241 ({ \ 242 const __typeof__(*(ptr)) __user *__p = (ptr); \ 243 might_fault(); \ 244 access_ok(__p, sizeof(*__p)) ? \ 245 __get_user((x), __p) : \ 246 ((x) = 0, -EFAULT); \ 247 }) 248 249 #define __put_user_asm(insn, x, ptr, err) \ 250 do { \ 251 uintptr_t __tmp; \ 252 __typeof__(*(ptr)) __x = x; \ 253 __enable_user_access(); \ 254 __asm__ __volatile__ ( \ 255 "1:\n" \ 256 " " insn " %z3, %2\n" \ 257 "2:\n" \ 258 " .section .fixup,\"ax\"\n" \ 259 " .balign 4\n" \ 260 "3:\n" \ 261 " li %0, %4\n" \ 262 " jump 2b, %1\n" \ 263 " .previous\n" \ 264 " .section __ex_table,\"a\"\n" \ 265 " .balign " RISCV_SZPTR "\n" \ 266 " " RISCV_PTR " 1b, 3b\n" \ 267 " .previous" \ 268 : "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \ 269 : "rJ" (__x), "i" (-EFAULT)); \ 270 __disable_user_access(); \ 271 } while (0) 272 273 #ifdef CONFIG_64BIT 274 #define __put_user_8(x, ptr, err) \ 275 __put_user_asm("sd", x, ptr, err) 276 #else /* !CONFIG_64BIT */ 277 #define __put_user_8(x, ptr, err) \ 278 do { \ 279 u32 __user *__ptr = (u32 __user *)(ptr); \ 280 u64 __x = (__typeof__((x)-(x)))(x); \ 281 uintptr_t __tmp; \ 282 __enable_user_access(); \ 283 __asm__ __volatile__ ( \ 284 "1:\n" \ 285 " sw %z4, %2\n" \ 286 "2:\n" \ 287 " sw %z5, %3\n" \ 288 "3:\n" \ 289 " .section .fixup,\"ax\"\n" \ 290 " .balign 4\n" \ 291 "4:\n" \ 292 " li %0, %6\n" \ 293 " jump 3b, %1\n" \ 294 " .previous\n" \ 295 " .section __ex_table,\"a\"\n" \ 296 " .balign " RISCV_SZPTR "\n" \ 297 " " RISCV_PTR " 1b, 4b\n" \ 298 " " RISCV_PTR " 2b, 4b\n" \ 299 " .previous" \ 300 : "+r" (err), "=r" (__tmp), \ 301 "=m" (__ptr[__LSW]), \ 302 "=m" (__ptr[__MSW]) \ 303 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \ 304 __disable_user_access(); \ 305 } while (0) 306 #endif /* CONFIG_64BIT */ 307 308 309 /** 310 * __put_user: - Write a simple value into user space, with less checking. 311 * @x: Value to copy to user space. 312 * @ptr: Destination address, in user space. 313 * 314 * Context: User context only. This function may sleep. 315 * 316 * This macro copies a single simple value from kernel space to user 317 * space. It supports simple types like char and int, but not larger 318 * data types like structures or arrays. 319 * 320 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 321 * to the result of dereferencing @ptr. 322 * 323 * Caller must check the pointer with access_ok() before calling this 324 * function. 325 * 326 * Returns zero on success, or -EFAULT on error. 327 */ 328 #define __put_user(x, ptr) \ 329 ({ \ 330 register long __pu_err = 0; \ 331 __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 332 __chk_user_ptr(__gu_ptr); \ 333 switch (sizeof(*__gu_ptr)) { \ 334 case 1: \ 335 __put_user_asm("sb", (x), __gu_ptr, __pu_err); \ 336 break; \ 337 case 2: \ 338 __put_user_asm("sh", (x), __gu_ptr, __pu_err); \ 339 break; \ 340 case 4: \ 341 __put_user_asm("sw", (x), __gu_ptr, __pu_err); \ 342 break; \ 343 case 8: \ 344 __put_user_8((x), __gu_ptr, __pu_err); \ 345 break; \ 346 default: \ 347 BUILD_BUG(); \ 348 } \ 349 __pu_err; \ 350 }) 351 352 /** 353 * put_user: - Write a simple value into user space. 354 * @x: Value to copy to user space. 355 * @ptr: Destination address, in user space. 356 * 357 * Context: User context only. This function may sleep. 358 * 359 * This macro copies a single simple value from kernel space to user 360 * space. It supports simple types like char and int, but not larger 361 * data types like structures or arrays. 362 * 363 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 364 * to the result of dereferencing @ptr. 365 * 366 * Returns zero on success, or -EFAULT on error. 367 */ 368 #define put_user(x, ptr) \ 369 ({ \ 370 __typeof__(*(ptr)) __user *__p = (ptr); \ 371 might_fault(); \ 372 access_ok(__p, sizeof(*__p)) ? \ 373 __put_user((x), __p) : \ 374 -EFAULT; \ 375 }) 376 377 378 extern unsigned long __must_check __asm_copy_to_user(void __user *to, 379 const void *from, unsigned long n); 380 extern unsigned long __must_check __asm_copy_from_user(void *to, 381 const void __user *from, unsigned long n); 382 383 static inline unsigned long 384 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 385 { 386 return __asm_copy_from_user(to, from, n); 387 } 388 389 static inline unsigned long 390 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 391 { 392 return __asm_copy_to_user(to, from, n); 393 } 394 395 extern long strncpy_from_user(char *dest, const char __user *src, long count); 396 397 extern long __must_check strlen_user(const char __user *str); 398 extern long __must_check strnlen_user(const char __user *str, long n); 399 400 extern 401 unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 402 403 static inline 404 unsigned long __must_check clear_user(void __user *to, unsigned long n) 405 { 406 might_fault(); 407 return access_ok(to, n) ? 408 __clear_user(to, n) : n; 409 } 410 411 /* 412 * Atomic compare-and-exchange, but with a fixup for userspace faults. Faults 413 * will set "err" to -EFAULT, while successful accesses return the previous 414 * value. 415 */ 416 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb) \ 417 ({ \ 418 __typeof__(ptr) __ptr = (ptr); \ 419 __typeof__(*(ptr)) __old = (old); \ 420 __typeof__(*(ptr)) __new = (new); \ 421 __typeof__(*(ptr)) __ret; \ 422 __typeof__(err) __err = 0; \ 423 register unsigned int __rc; \ 424 __enable_user_access(); \ 425 switch (size) { \ 426 case 4: \ 427 __asm__ __volatile__ ( \ 428 "0:\n" \ 429 " lr.w" #scb " %[ret], %[ptr]\n" \ 430 " bne %[ret], %z[old], 1f\n" \ 431 " sc.w" #lrb " %[rc], %z[new], %[ptr]\n" \ 432 " bnez %[rc], 0b\n" \ 433 "1:\n" \ 434 ".section .fixup,\"ax\"\n" \ 435 ".balign 4\n" \ 436 "2:\n" \ 437 " li %[err], %[efault]\n" \ 438 " jump 1b, %[rc]\n" \ 439 ".previous\n" \ 440 ".section __ex_table,\"a\"\n" \ 441 ".balign " RISCV_SZPTR "\n" \ 442 " " RISCV_PTR " 1b, 2b\n" \ 443 ".previous\n" \ 444 : [ret] "=&r" (__ret), \ 445 [rc] "=&r" (__rc), \ 446 [ptr] "+A" (*__ptr), \ 447 [err] "=&r" (__err) \ 448 : [old] "rJ" (__old), \ 449 [new] "rJ" (__new), \ 450 [efault] "i" (-EFAULT)); \ 451 break; \ 452 case 8: \ 453 __asm__ __volatile__ ( \ 454 "0:\n" \ 455 " lr.d" #scb " %[ret], %[ptr]\n" \ 456 " bne %[ret], %z[old], 1f\n" \ 457 " sc.d" #lrb " %[rc], %z[new], %[ptr]\n" \ 458 " bnez %[rc], 0b\n" \ 459 "1:\n" \ 460 ".section .fixup,\"ax\"\n" \ 461 ".balign 4\n" \ 462 "2:\n" \ 463 " li %[err], %[efault]\n" \ 464 " jump 1b, %[rc]\n" \ 465 ".previous\n" \ 466 ".section __ex_table,\"a\"\n" \ 467 ".balign " RISCV_SZPTR "\n" \ 468 " " RISCV_PTR " 1b, 2b\n" \ 469 ".previous\n" \ 470 : [ret] "=&r" (__ret), \ 471 [rc] "=&r" (__rc), \ 472 [ptr] "+A" (*__ptr), \ 473 [err] "=&r" (__err) \ 474 : [old] "rJ" (__old), \ 475 [new] "rJ" (__new), \ 476 [efault] "i" (-EFAULT)); \ 477 break; \ 478 default: \ 479 BUILD_BUG(); \ 480 } \ 481 __disable_user_access(); \ 482 (err) = __err; \ 483 __ret; \ 484 }) 485 486 #endif /* _ASM_RISCV_UACCESS_H */ 487