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_ds() (KERNEL_DS) 45 #define get_fs() (current_thread_info()->addr_limit) 46 47 static inline void set_fs(mm_segment_t fs) 48 { 49 current_thread_info()->addr_limit = fs; 50 } 51 52 #define segment_eq(a, b) ((a) == (b)) 53 54 #define user_addr_max() (get_fs()) 55 56 57 /** 58 * access_ok: - Checks if a user space pointer is valid 59 * @addr: User space pointer to start of block to check 60 * @size: Size of block to check 61 * 62 * Context: User context only. This function may sleep. 63 * 64 * Checks if a pointer to a block of memory in user space is valid. 65 * 66 * Returns true (nonzero) if the memory block may be valid, false (zero) 67 * if it is definitely invalid. 68 * 69 * Note that, depending on architecture, this function probably just 70 * checks that the pointer is in the user space range - after calling 71 * this function, memory access functions may still return -EFAULT. 72 */ 73 #define access_ok(addr, size) ({ \ 74 __chk_user_ptr(addr); \ 75 likely(__access_ok((unsigned long __force)(addr), (size))); \ 76 }) 77 78 /* 79 * Ensure that the range [addr, addr+size) is within the process's 80 * address space 81 */ 82 static inline int __access_ok(unsigned long addr, unsigned long size) 83 { 84 const mm_segment_t fs = get_fs(); 85 86 return (size <= fs) && (addr <= (fs - size)); 87 } 88 89 /* 90 * The exception table consists of pairs of addresses: the first is the 91 * address of an instruction that is allowed to fault, and the second is 92 * the address at which the program should continue. No registers are 93 * modified, so it is entirely up to the continuation code to figure out 94 * what to do. 95 * 96 * All the routines below use bits of fixup code that are out of line 97 * with the main instruction path. This means when everything is well, 98 * we don't even have to jump over them. Further, they do not intrude 99 * on our cache or tlb entries. 100 */ 101 102 struct exception_table_entry { 103 unsigned long insn, fixup; 104 }; 105 106 extern int fixup_exception(struct pt_regs *state); 107 108 #if defined(__LITTLE_ENDIAN) 109 #define __MSW 1 110 #define __LSW 0 111 #elif defined(__BIG_ENDIAN) 112 #define __MSW 0 113 #define __LSW 1 114 #else 115 #error "Unknown endianness" 116 #endif 117 118 /* 119 * The "__xxx" versions of the user access functions do not verify the address 120 * space - it must have been done previously with a separate "access_ok()" 121 * call. 122 */ 123 124 #define __get_user_asm(insn, x, ptr, err) \ 125 do { \ 126 uintptr_t __tmp; \ 127 __typeof__(x) __x; \ 128 __enable_user_access(); \ 129 __asm__ __volatile__ ( \ 130 "1:\n" \ 131 " " insn " %1, %3\n" \ 132 "2:\n" \ 133 " .section .fixup,\"ax\"\n" \ 134 " .balign 4\n" \ 135 "3:\n" \ 136 " li %0, %4\n" \ 137 " li %1, 0\n" \ 138 " jump 2b, %2\n" \ 139 " .previous\n" \ 140 " .section __ex_table,\"a\"\n" \ 141 " .balign " RISCV_SZPTR "\n" \ 142 " " RISCV_PTR " 1b, 3b\n" \ 143 " .previous" \ 144 : "+r" (err), "=&r" (__x), "=r" (__tmp) \ 145 : "m" (*(ptr)), "i" (-EFAULT)); \ 146 __disable_user_access(); \ 147 (x) = __x; \ 148 } while (0) 149 150 #ifdef CONFIG_64BIT 151 #define __get_user_8(x, ptr, err) \ 152 __get_user_asm("ld", x, ptr, err) 153 #else /* !CONFIG_64BIT */ 154 #define __get_user_8(x, ptr, err) \ 155 do { \ 156 u32 __user *__ptr = (u32 __user *)(ptr); \ 157 u32 __lo, __hi; \ 158 uintptr_t __tmp; \ 159 __enable_user_access(); \ 160 __asm__ __volatile__ ( \ 161 "1:\n" \ 162 " lw %1, %4\n" \ 163 "2:\n" \ 164 " lw %2, %5\n" \ 165 "3:\n" \ 166 " .section .fixup,\"ax\"\n" \ 167 " .balign 4\n" \ 168 "4:\n" \ 169 " li %0, %6\n" \ 170 " li %1, 0\n" \ 171 " li %2, 0\n" \ 172 " jump 3b, %3\n" \ 173 " .previous\n" \ 174 " .section __ex_table,\"a\"\n" \ 175 " .balign " RISCV_SZPTR "\n" \ 176 " " RISCV_PTR " 1b, 4b\n" \ 177 " " RISCV_PTR " 2b, 4b\n" \ 178 " .previous" \ 179 : "+r" (err), "=&r" (__lo), "=r" (__hi), \ 180 "=r" (__tmp) \ 181 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]), \ 182 "i" (-EFAULT)); \ 183 __disable_user_access(); \ 184 (x) = (__typeof__(x))((__typeof__((x)-(x)))( \ 185 (((u64)__hi << 32) | __lo))); \ 186 } while (0) 187 #endif /* CONFIG_64BIT */ 188 189 190 /** 191 * __get_user: - Get a simple variable from user space, with less checking. 192 * @x: Variable to store result. 193 * @ptr: Source address, in user space. 194 * 195 * Context: User context only. This function may sleep. 196 * 197 * This macro copies a single simple variable from user space to kernel 198 * space. It supports simple types like char and int, but not larger 199 * data types like structures or arrays. 200 * 201 * @ptr must have pointer-to-simple-variable type, and the result of 202 * dereferencing @ptr must be assignable to @x without a cast. 203 * 204 * Caller must check the pointer with access_ok() before calling this 205 * function. 206 * 207 * Returns zero on success, or -EFAULT on error. 208 * On error, the variable @x is set to zero. 209 */ 210 #define __get_user(x, ptr) \ 211 ({ \ 212 register long __gu_err = 0; \ 213 const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 214 __chk_user_ptr(__gu_ptr); \ 215 switch (sizeof(*__gu_ptr)) { \ 216 case 1: \ 217 __get_user_asm("lb", (x), __gu_ptr, __gu_err); \ 218 break; \ 219 case 2: \ 220 __get_user_asm("lh", (x), __gu_ptr, __gu_err); \ 221 break; \ 222 case 4: \ 223 __get_user_asm("lw", (x), __gu_ptr, __gu_err); \ 224 break; \ 225 case 8: \ 226 __get_user_8((x), __gu_ptr, __gu_err); \ 227 break; \ 228 default: \ 229 BUILD_BUG(); \ 230 } \ 231 __gu_err; \ 232 }) 233 234 /** 235 * get_user: - Get a simple variable from user space. 236 * @x: Variable to store result. 237 * @ptr: Source address, in user space. 238 * 239 * Context: User context only. This function may sleep. 240 * 241 * This macro copies a single simple variable from user space to kernel 242 * space. It supports simple types like char and int, but not larger 243 * data types like structures or arrays. 244 * 245 * @ptr must have pointer-to-simple-variable type, and the result of 246 * dereferencing @ptr must be assignable to @x without a cast. 247 * 248 * Returns zero on success, or -EFAULT on error. 249 * On error, the variable @x is set to zero. 250 */ 251 #define get_user(x, ptr) \ 252 ({ \ 253 const __typeof__(*(ptr)) __user *__p = (ptr); \ 254 might_fault(); \ 255 access_ok(__p, sizeof(*__p)) ? \ 256 __get_user((x), __p) : \ 257 ((x) = 0, -EFAULT); \ 258 }) 259 260 #define __put_user_asm(insn, x, ptr, err) \ 261 do { \ 262 uintptr_t __tmp; \ 263 __typeof__(*(ptr)) __x = x; \ 264 __enable_user_access(); \ 265 __asm__ __volatile__ ( \ 266 "1:\n" \ 267 " " insn " %z3, %2\n" \ 268 "2:\n" \ 269 " .section .fixup,\"ax\"\n" \ 270 " .balign 4\n" \ 271 "3:\n" \ 272 " li %0, %4\n" \ 273 " jump 2b, %1\n" \ 274 " .previous\n" \ 275 " .section __ex_table,\"a\"\n" \ 276 " .balign " RISCV_SZPTR "\n" \ 277 " " RISCV_PTR " 1b, 3b\n" \ 278 " .previous" \ 279 : "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \ 280 : "rJ" (__x), "i" (-EFAULT)); \ 281 __disable_user_access(); \ 282 } while (0) 283 284 #ifdef CONFIG_64BIT 285 #define __put_user_8(x, ptr, err) \ 286 __put_user_asm("sd", x, ptr, err) 287 #else /* !CONFIG_64BIT */ 288 #define __put_user_8(x, ptr, err) \ 289 do { \ 290 u32 __user *__ptr = (u32 __user *)(ptr); \ 291 u64 __x = (__typeof__((x)-(x)))(x); \ 292 uintptr_t __tmp; \ 293 __enable_user_access(); \ 294 __asm__ __volatile__ ( \ 295 "1:\n" \ 296 " sw %z4, %2\n" \ 297 "2:\n" \ 298 " sw %z5, %3\n" \ 299 "3:\n" \ 300 " .section .fixup,\"ax\"\n" \ 301 " .balign 4\n" \ 302 "4:\n" \ 303 " li %0, %6\n" \ 304 " jump 2b, %1\n" \ 305 " .previous\n" \ 306 " .section __ex_table,\"a\"\n" \ 307 " .balign " RISCV_SZPTR "\n" \ 308 " " RISCV_PTR " 1b, 4b\n" \ 309 " " RISCV_PTR " 2b, 4b\n" \ 310 " .previous" \ 311 : "+r" (err), "=r" (__tmp), \ 312 "=m" (__ptr[__LSW]), \ 313 "=m" (__ptr[__MSW]) \ 314 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \ 315 __disable_user_access(); \ 316 } while (0) 317 #endif /* CONFIG_64BIT */ 318 319 320 /** 321 * __put_user: - Write a simple value into user space, with less checking. 322 * @x: Value to copy to user space. 323 * @ptr: Destination address, in user space. 324 * 325 * Context: User context only. This function may sleep. 326 * 327 * This macro copies a single simple value from kernel space to user 328 * space. It supports simple types like char and int, but not larger 329 * data types like structures or arrays. 330 * 331 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 332 * to the result of dereferencing @ptr. 333 * 334 * Caller must check the pointer with access_ok() before calling this 335 * function. 336 * 337 * Returns zero on success, or -EFAULT on error. 338 */ 339 #define __put_user(x, ptr) \ 340 ({ \ 341 register long __pu_err = 0; \ 342 __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 343 __chk_user_ptr(__gu_ptr); \ 344 switch (sizeof(*__gu_ptr)) { \ 345 case 1: \ 346 __put_user_asm("sb", (x), __gu_ptr, __pu_err); \ 347 break; \ 348 case 2: \ 349 __put_user_asm("sh", (x), __gu_ptr, __pu_err); \ 350 break; \ 351 case 4: \ 352 __put_user_asm("sw", (x), __gu_ptr, __pu_err); \ 353 break; \ 354 case 8: \ 355 __put_user_8((x), __gu_ptr, __pu_err); \ 356 break; \ 357 default: \ 358 BUILD_BUG(); \ 359 } \ 360 __pu_err; \ 361 }) 362 363 /** 364 * put_user: - Write a simple value into user space. 365 * @x: Value to copy to user space. 366 * @ptr: Destination address, in user space. 367 * 368 * Context: User context only. This function may sleep. 369 * 370 * This macro copies a single simple value from kernel space to user 371 * space. It supports simple types like char and int, but not larger 372 * data types like structures or arrays. 373 * 374 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 375 * to the result of dereferencing @ptr. 376 * 377 * Returns zero on success, or -EFAULT on error. 378 */ 379 #define put_user(x, ptr) \ 380 ({ \ 381 __typeof__(*(ptr)) __user *__p = (ptr); \ 382 might_fault(); \ 383 access_ok(__p, sizeof(*__p)) ? \ 384 __put_user((x), __p) : \ 385 -EFAULT; \ 386 }) 387 388 389 extern unsigned long __must_check __asm_copy_to_user(void __user *to, 390 const void *from, unsigned long n); 391 extern unsigned long __must_check __asm_copy_from_user(void *to, 392 const void __user *from, unsigned long n); 393 394 static inline unsigned long 395 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 396 { 397 return __asm_copy_from_user(to, from, n); 398 } 399 400 static inline unsigned long 401 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 402 { 403 return __asm_copy_to_user(to, from, n); 404 } 405 406 extern long strncpy_from_user(char *dest, const char __user *src, long count); 407 408 extern long __must_check strlen_user(const char __user *str); 409 extern long __must_check strnlen_user(const char __user *str, long n); 410 411 extern 412 unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 413 414 static inline 415 unsigned long __must_check clear_user(void __user *to, unsigned long n) 416 { 417 might_fault(); 418 return access_ok(to, n) ? 419 __clear_user(to, n) : n; 420 } 421 422 /* 423 * Atomic compare-and-exchange, but with a fixup for userspace faults. Faults 424 * will set "err" to -EFAULT, while successful accesses return the previous 425 * value. 426 */ 427 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb) \ 428 ({ \ 429 __typeof__(ptr) __ptr = (ptr); \ 430 __typeof__(*(ptr)) __old = (old); \ 431 __typeof__(*(ptr)) __new = (new); \ 432 __typeof__(*(ptr)) __ret; \ 433 __typeof__(err) __err = 0; \ 434 register unsigned int __rc; \ 435 __enable_user_access(); \ 436 switch (size) { \ 437 case 4: \ 438 __asm__ __volatile__ ( \ 439 "0:\n" \ 440 " lr.w" #scb " %[ret], %[ptr]\n" \ 441 " bne %[ret], %z[old], 1f\n" \ 442 " sc.w" #lrb " %[rc], %z[new], %[ptr]\n" \ 443 " bnez %[rc], 0b\n" \ 444 "1:\n" \ 445 ".section .fixup,\"ax\"\n" \ 446 ".balign 4\n" \ 447 "2:\n" \ 448 " li %[err], %[efault]\n" \ 449 " jump 1b, %[rc]\n" \ 450 ".previous\n" \ 451 ".section __ex_table,\"a\"\n" \ 452 ".balign " RISCV_SZPTR "\n" \ 453 " " RISCV_PTR " 1b, 2b\n" \ 454 ".previous\n" \ 455 : [ret] "=&r" (__ret), \ 456 [rc] "=&r" (__rc), \ 457 [ptr] "+A" (*__ptr), \ 458 [err] "=&r" (__err) \ 459 : [old] "rJ" (__old), \ 460 [new] "rJ" (__new), \ 461 [efault] "i" (-EFAULT)); \ 462 break; \ 463 case 8: \ 464 __asm__ __volatile__ ( \ 465 "0:\n" \ 466 " lr.d" #scb " %[ret], %[ptr]\n" \ 467 " bne %[ret], %z[old], 1f\n" \ 468 " sc.d" #lrb " %[rc], %z[new], %[ptr]\n" \ 469 " bnez %[rc], 0b\n" \ 470 "1:\n" \ 471 ".section .fixup,\"ax\"\n" \ 472 ".balign 4\n" \ 473 "2:\n" \ 474 " li %[err], %[efault]\n" \ 475 " jump 1b, %[rc]\n" \ 476 ".previous\n" \ 477 ".section __ex_table,\"a\"\n" \ 478 ".balign " RISCV_SZPTR "\n" \ 479 " " RISCV_PTR " 1b, 2b\n" \ 480 ".previous\n" \ 481 : [ret] "=&r" (__ret), \ 482 [rc] "=&r" (__rc), \ 483 [ptr] "+A" (*__ptr), \ 484 [err] "=&r" (__err) \ 485 : [old] "rJ" (__old), \ 486 [new] "rJ" (__new), \ 487 [efault] "i" (-EFAULT)); \ 488 break; \ 489 default: \ 490 BUILD_BUG(); \ 491 } \ 492 __disable_user_access(); \ 493 (err) = __err; \ 494 __ret; \ 495 }) 496 497 #endif /* _ASM_RISCV_UACCESS_H */ 498