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/asm.h> 27 28 #define __enable_user_access() \ 29 __asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory") 30 #define __disable_user_access() \ 31 __asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory") 32 33 /* 34 * The fs value determines whether argument validity checking should be 35 * performed or not. If get_fs() == USER_DS, checking is performed, with 36 * get_fs() == KERNEL_DS, checking is bypassed. 37 * 38 * For historical reasons, these macros are grossly misnamed. 39 */ 40 41 #define KERNEL_DS (~0UL) 42 #define USER_DS (TASK_SIZE) 43 44 #define get_fs() (current_thread_info()->addr_limit) 45 46 static inline void set_fs(mm_segment_t fs) 47 { 48 current_thread_info()->addr_limit = fs; 49 } 50 51 #define segment_eq(a, b) ((a) == (b)) 52 53 #define user_addr_max() (get_fs()) 54 55 56 /** 57 * access_ok: - Checks if a user space pointer is valid 58 * @addr: User space pointer to start of block to check 59 * @size: Size of block to check 60 * 61 * Context: User context only. This function may sleep. 62 * 63 * Checks if a pointer to a block of memory in user space is valid. 64 * 65 * Returns true (nonzero) if the memory block may be valid, false (zero) 66 * if it is definitely invalid. 67 * 68 * Note that, depending on architecture, this function probably just 69 * checks that the pointer is in the user space range - after calling 70 * this function, memory access functions may still return -EFAULT. 71 */ 72 #define access_ok(addr, size) ({ \ 73 __chk_user_ptr(addr); \ 74 likely(__access_ok((unsigned long __force)(addr), (size))); \ 75 }) 76 77 /* 78 * Ensure that the range [addr, addr+size) is within the process's 79 * address space 80 */ 81 static inline int __access_ok(unsigned long addr, unsigned long size) 82 { 83 const mm_segment_t fs = get_fs(); 84 85 return (size <= fs) && (addr <= (fs - size)); 86 } 87 88 /* 89 * The exception table consists of pairs of addresses: the first is the 90 * address of an instruction that is allowed to fault, and the second is 91 * the address at which the program should continue. No registers are 92 * modified, so it is entirely up to the continuation code to figure out 93 * what to do. 94 * 95 * All the routines below use bits of fixup code that are out of line 96 * with the main instruction path. This means when everything is well, 97 * we don't even have to jump over them. Further, they do not intrude 98 * on our cache or tlb entries. 99 */ 100 101 struct exception_table_entry { 102 unsigned long insn, fixup; 103 }; 104 105 extern int fixup_exception(struct pt_regs *state); 106 107 #if defined(__LITTLE_ENDIAN) 108 #define __MSW 1 109 #define __LSW 0 110 #elif defined(__BIG_ENDIAN) 111 #define __MSW 0 112 #define __LSW 1 113 #else 114 #error "Unknown endianness" 115 #endif 116 117 /* 118 * The "__xxx" versions of the user access functions do not verify the address 119 * space - it must have been done previously with a separate "access_ok()" 120 * call. 121 */ 122 123 #define __get_user_asm(insn, x, ptr, err) \ 124 do { \ 125 uintptr_t __tmp; \ 126 __typeof__(x) __x; \ 127 __enable_user_access(); \ 128 __asm__ __volatile__ ( \ 129 "1:\n" \ 130 " " insn " %1, %3\n" \ 131 "2:\n" \ 132 " .section .fixup,\"ax\"\n" \ 133 " .balign 4\n" \ 134 "3:\n" \ 135 " li %0, %4\n" \ 136 " li %1, 0\n" \ 137 " jump 2b, %2\n" \ 138 " .previous\n" \ 139 " .section __ex_table,\"a\"\n" \ 140 " .balign " RISCV_SZPTR "\n" \ 141 " " RISCV_PTR " 1b, 3b\n" \ 142 " .previous" \ 143 : "+r" (err), "=&r" (__x), "=r" (__tmp) \ 144 : "m" (*(ptr)), "i" (-EFAULT)); \ 145 __disable_user_access(); \ 146 (x) = __x; \ 147 } while (0) 148 149 #ifdef CONFIG_64BIT 150 #define __get_user_8(x, ptr, err) \ 151 __get_user_asm("ld", x, ptr, err) 152 #else /* !CONFIG_64BIT */ 153 #define __get_user_8(x, ptr, err) \ 154 do { \ 155 u32 __user *__ptr = (u32 __user *)(ptr); \ 156 u32 __lo, __hi; \ 157 uintptr_t __tmp; \ 158 __enable_user_access(); \ 159 __asm__ __volatile__ ( \ 160 "1:\n" \ 161 " lw %1, %4\n" \ 162 "2:\n" \ 163 " lw %2, %5\n" \ 164 "3:\n" \ 165 " .section .fixup,\"ax\"\n" \ 166 " .balign 4\n" \ 167 "4:\n" \ 168 " li %0, %6\n" \ 169 " li %1, 0\n" \ 170 " li %2, 0\n" \ 171 " jump 3b, %3\n" \ 172 " .previous\n" \ 173 " .section __ex_table,\"a\"\n" \ 174 " .balign " RISCV_SZPTR "\n" \ 175 " " RISCV_PTR " 1b, 4b\n" \ 176 " " RISCV_PTR " 2b, 4b\n" \ 177 " .previous" \ 178 : "+r" (err), "=&r" (__lo), "=r" (__hi), \ 179 "=r" (__tmp) \ 180 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]), \ 181 "i" (-EFAULT)); \ 182 __disable_user_access(); \ 183 (x) = (__typeof__(x))((__typeof__((x)-(x)))( \ 184 (((u64)__hi << 32) | __lo))); \ 185 } while (0) 186 #endif /* CONFIG_64BIT */ 187 188 189 /** 190 * __get_user: - Get a simple variable from user space, with less checking. 191 * @x: Variable to store result. 192 * @ptr: Source address, in user space. 193 * 194 * Context: User context only. This function may sleep. 195 * 196 * This macro copies a single simple variable from user space to kernel 197 * space. It supports simple types like char and int, but not larger 198 * data types like structures or arrays. 199 * 200 * @ptr must have pointer-to-simple-variable type, and the result of 201 * dereferencing @ptr must be assignable to @x without a cast. 202 * 203 * Caller must check the pointer with access_ok() before calling this 204 * function. 205 * 206 * Returns zero on success, or -EFAULT on error. 207 * On error, the variable @x is set to zero. 208 */ 209 #define __get_user(x, ptr) \ 210 ({ \ 211 register long __gu_err = 0; \ 212 const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 213 __chk_user_ptr(__gu_ptr); \ 214 switch (sizeof(*__gu_ptr)) { \ 215 case 1: \ 216 __get_user_asm("lb", (x), __gu_ptr, __gu_err); \ 217 break; \ 218 case 2: \ 219 __get_user_asm("lh", (x), __gu_ptr, __gu_err); \ 220 break; \ 221 case 4: \ 222 __get_user_asm("lw", (x), __gu_ptr, __gu_err); \ 223 break; \ 224 case 8: \ 225 __get_user_8((x), __gu_ptr, __gu_err); \ 226 break; \ 227 default: \ 228 BUILD_BUG(); \ 229 } \ 230 __gu_err; \ 231 }) 232 233 /** 234 * get_user: - Get a simple variable from user space. 235 * @x: Variable to store result. 236 * @ptr: Source address, in user space. 237 * 238 * Context: User context only. This function may sleep. 239 * 240 * This macro copies a single simple variable from user space to kernel 241 * space. It supports simple types like char and int, but not larger 242 * data types like structures or arrays. 243 * 244 * @ptr must have pointer-to-simple-variable type, and the result of 245 * dereferencing @ptr must be assignable to @x without a cast. 246 * 247 * Returns zero on success, or -EFAULT on error. 248 * On error, the variable @x is set to zero. 249 */ 250 #define get_user(x, ptr) \ 251 ({ \ 252 const __typeof__(*(ptr)) __user *__p = (ptr); \ 253 might_fault(); \ 254 access_ok(__p, sizeof(*__p)) ? \ 255 __get_user((x), __p) : \ 256 ((x) = 0, -EFAULT); \ 257 }) 258 259 #define __put_user_asm(insn, x, ptr, err) \ 260 do { \ 261 uintptr_t __tmp; \ 262 __typeof__(*(ptr)) __x = x; \ 263 __enable_user_access(); \ 264 __asm__ __volatile__ ( \ 265 "1:\n" \ 266 " " insn " %z3, %2\n" \ 267 "2:\n" \ 268 " .section .fixup,\"ax\"\n" \ 269 " .balign 4\n" \ 270 "3:\n" \ 271 " li %0, %4\n" \ 272 " jump 2b, %1\n" \ 273 " .previous\n" \ 274 " .section __ex_table,\"a\"\n" \ 275 " .balign " RISCV_SZPTR "\n" \ 276 " " RISCV_PTR " 1b, 3b\n" \ 277 " .previous" \ 278 : "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \ 279 : "rJ" (__x), "i" (-EFAULT)); \ 280 __disable_user_access(); \ 281 } while (0) 282 283 #ifdef CONFIG_64BIT 284 #define __put_user_8(x, ptr, err) \ 285 __put_user_asm("sd", x, ptr, err) 286 #else /* !CONFIG_64BIT */ 287 #define __put_user_8(x, ptr, err) \ 288 do { \ 289 u32 __user *__ptr = (u32 __user *)(ptr); \ 290 u64 __x = (__typeof__((x)-(x)))(x); \ 291 uintptr_t __tmp; \ 292 __enable_user_access(); \ 293 __asm__ __volatile__ ( \ 294 "1:\n" \ 295 " sw %z4, %2\n" \ 296 "2:\n" \ 297 " sw %z5, %3\n" \ 298 "3:\n" \ 299 " .section .fixup,\"ax\"\n" \ 300 " .balign 4\n" \ 301 "4:\n" \ 302 " li %0, %6\n" \ 303 " jump 2b, %1\n" \ 304 " .previous\n" \ 305 " .section __ex_table,\"a\"\n" \ 306 " .balign " RISCV_SZPTR "\n" \ 307 " " RISCV_PTR " 1b, 4b\n" \ 308 " " RISCV_PTR " 2b, 4b\n" \ 309 " .previous" \ 310 : "+r" (err), "=r" (__tmp), \ 311 "=m" (__ptr[__LSW]), \ 312 "=m" (__ptr[__MSW]) \ 313 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \ 314 __disable_user_access(); \ 315 } while (0) 316 #endif /* CONFIG_64BIT */ 317 318 319 /** 320 * __put_user: - Write a simple value into user space, with less checking. 321 * @x: Value to copy to user space. 322 * @ptr: Destination address, in user space. 323 * 324 * Context: User context only. This function may sleep. 325 * 326 * This macro copies a single simple value from kernel space to user 327 * space. It supports simple types like char and int, but not larger 328 * data types like structures or arrays. 329 * 330 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 331 * to the result of dereferencing @ptr. 332 * 333 * Caller must check the pointer with access_ok() before calling this 334 * function. 335 * 336 * Returns zero on success, or -EFAULT on error. 337 */ 338 #define __put_user(x, ptr) \ 339 ({ \ 340 register long __pu_err = 0; \ 341 __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 342 __chk_user_ptr(__gu_ptr); \ 343 switch (sizeof(*__gu_ptr)) { \ 344 case 1: \ 345 __put_user_asm("sb", (x), __gu_ptr, __pu_err); \ 346 break; \ 347 case 2: \ 348 __put_user_asm("sh", (x), __gu_ptr, __pu_err); \ 349 break; \ 350 case 4: \ 351 __put_user_asm("sw", (x), __gu_ptr, __pu_err); \ 352 break; \ 353 case 8: \ 354 __put_user_8((x), __gu_ptr, __pu_err); \ 355 break; \ 356 default: \ 357 BUILD_BUG(); \ 358 } \ 359 __pu_err; \ 360 }) 361 362 /** 363 * put_user: - Write a simple value into user space. 364 * @x: Value to copy to user space. 365 * @ptr: Destination address, in user space. 366 * 367 * Context: User context only. This function may sleep. 368 * 369 * This macro copies a single simple value from kernel space to user 370 * space. It supports simple types like char and int, but not larger 371 * data types like structures or arrays. 372 * 373 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 374 * to the result of dereferencing @ptr. 375 * 376 * Returns zero on success, or -EFAULT on error. 377 */ 378 #define put_user(x, ptr) \ 379 ({ \ 380 __typeof__(*(ptr)) __user *__p = (ptr); \ 381 might_fault(); \ 382 access_ok(__p, sizeof(*__p)) ? \ 383 __put_user((x), __p) : \ 384 -EFAULT; \ 385 }) 386 387 388 extern unsigned long __must_check __asm_copy_to_user(void __user *to, 389 const void *from, unsigned long n); 390 extern unsigned long __must_check __asm_copy_from_user(void *to, 391 const void __user *from, unsigned long n); 392 393 static inline unsigned long 394 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 395 { 396 return __asm_copy_from_user(to, from, n); 397 } 398 399 static inline unsigned long 400 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 401 { 402 return __asm_copy_to_user(to, from, n); 403 } 404 405 extern long strncpy_from_user(char *dest, const char __user *src, long count); 406 407 extern long __must_check strlen_user(const char __user *str); 408 extern long __must_check strnlen_user(const char __user *str, long n); 409 410 extern 411 unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 412 413 static inline 414 unsigned long __must_check clear_user(void __user *to, unsigned long n) 415 { 416 might_fault(); 417 return access_ok(to, n) ? 418 __clear_user(to, n) : n; 419 } 420 421 /* 422 * Atomic compare-and-exchange, but with a fixup for userspace faults. Faults 423 * will set "err" to -EFAULT, while successful accesses return the previous 424 * value. 425 */ 426 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb) \ 427 ({ \ 428 __typeof__(ptr) __ptr = (ptr); \ 429 __typeof__(*(ptr)) __old = (old); \ 430 __typeof__(*(ptr)) __new = (new); \ 431 __typeof__(*(ptr)) __ret; \ 432 __typeof__(err) __err = 0; \ 433 register unsigned int __rc; \ 434 __enable_user_access(); \ 435 switch (size) { \ 436 case 4: \ 437 __asm__ __volatile__ ( \ 438 "0:\n" \ 439 " lr.w" #scb " %[ret], %[ptr]\n" \ 440 " bne %[ret], %z[old], 1f\n" \ 441 " sc.w" #lrb " %[rc], %z[new], %[ptr]\n" \ 442 " bnez %[rc], 0b\n" \ 443 "1:\n" \ 444 ".section .fixup,\"ax\"\n" \ 445 ".balign 4\n" \ 446 "2:\n" \ 447 " li %[err], %[efault]\n" \ 448 " jump 1b, %[rc]\n" \ 449 ".previous\n" \ 450 ".section __ex_table,\"a\"\n" \ 451 ".balign " RISCV_SZPTR "\n" \ 452 " " RISCV_PTR " 1b, 2b\n" \ 453 ".previous\n" \ 454 : [ret] "=&r" (__ret), \ 455 [rc] "=&r" (__rc), \ 456 [ptr] "+A" (*__ptr), \ 457 [err] "=&r" (__err) \ 458 : [old] "rJ" (__old), \ 459 [new] "rJ" (__new), \ 460 [efault] "i" (-EFAULT)); \ 461 break; \ 462 case 8: \ 463 __asm__ __volatile__ ( \ 464 "0:\n" \ 465 " lr.d" #scb " %[ret], %[ptr]\n" \ 466 " bne %[ret], %z[old], 1f\n" \ 467 " sc.d" #lrb " %[rc], %z[new], %[ptr]\n" \ 468 " bnez %[rc], 0b\n" \ 469 "1:\n" \ 470 ".section .fixup,\"ax\"\n" \ 471 ".balign 4\n" \ 472 "2:\n" \ 473 " li %[err], %[efault]\n" \ 474 " jump 1b, %[rc]\n" \ 475 ".previous\n" \ 476 ".section __ex_table,\"a\"\n" \ 477 ".balign " RISCV_SZPTR "\n" \ 478 " " RISCV_PTR " 1b, 2b\n" \ 479 ".previous\n" \ 480 : [ret] "=&r" (__ret), \ 481 [rc] "=&r" (__rc), \ 482 [ptr] "+A" (*__ptr), \ 483 [err] "=&r" (__err) \ 484 : [old] "rJ" (__old), \ 485 [new] "rJ" (__new), \ 486 [efault] "i" (-EFAULT)); \ 487 break; \ 488 default: \ 489 BUILD_BUG(); \ 490 } \ 491 __disable_user_access(); \ 492 (err) = __err; \ 493 __ret; \ 494 }) 495 496 #endif /* _ASM_RISCV_UACCESS_H */ 497