1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2012 Regents of the University of California 4 * 5 * This file was copied from include/asm-generic/uaccess.h 6 */ 7 8 #ifndef _ASM_RISCV_UACCESS_H 9 #define _ASM_RISCV_UACCESS_H 10 11 /* 12 * User space memory access functions 13 */ 14 #ifdef CONFIG_MMU 15 #include <linux/errno.h> 16 #include <linux/compiler.h> 17 #include <linux/thread_info.h> 18 #include <asm/byteorder.h> 19 #include <asm/extable.h> 20 #include <asm/asm.h> 21 22 #define __enable_user_access() \ 23 __asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory") 24 #define __disable_user_access() \ 25 __asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory") 26 27 /* 28 * The fs value determines whether argument validity checking should be 29 * performed or not. If get_fs() == USER_DS, checking is performed, with 30 * get_fs() == KERNEL_DS, checking is bypassed. 31 * 32 * For historical reasons, these macros are grossly misnamed. 33 */ 34 35 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) 36 37 #define KERNEL_DS MAKE_MM_SEG(~0UL) 38 #define USER_DS MAKE_MM_SEG(TASK_SIZE) 39 40 #define get_fs() (current_thread_info()->addr_limit) 41 42 static inline void set_fs(mm_segment_t fs) 43 { 44 current_thread_info()->addr_limit = fs; 45 } 46 47 #define segment_eq(a, b) ((a).seg == (b).seg) 48 49 #define user_addr_max() (get_fs().seg) 50 51 52 /** 53 * access_ok: - Checks if a user space pointer is valid 54 * @addr: User space pointer to start of block to check 55 * @size: Size of block to check 56 * 57 * Context: User context only. This function may sleep. 58 * 59 * Checks if a pointer to a block of memory in user space is valid. 60 * 61 * Returns true (nonzero) if the memory block may be valid, false (zero) 62 * if it is definitely invalid. 63 * 64 * Note that, depending on architecture, this function probably just 65 * checks that the pointer is in the user space range - after calling 66 * this function, memory access functions may still return -EFAULT. 67 */ 68 #define access_ok(addr, size) ({ \ 69 __chk_user_ptr(addr); \ 70 likely(__access_ok((unsigned long __force)(addr), (size))); \ 71 }) 72 73 /* 74 * Ensure that the range [addr, addr+size) is within the process's 75 * address space 76 */ 77 static inline int __access_ok(unsigned long addr, unsigned long size) 78 { 79 const mm_segment_t fs = get_fs(); 80 81 return size <= fs.seg && addr <= fs.seg - size; 82 } 83 84 /* 85 * The exception table consists of pairs of addresses: the first is the 86 * address of an instruction that is allowed to fault, and the second is 87 * the address at which the program should continue. No registers are 88 * modified, so it is entirely up to the continuation code to figure out 89 * what to do. 90 * 91 * All the routines below use bits of fixup code that are out of line 92 * with the main instruction path. This means when everything is well, 93 * we don't even have to jump over them. Further, they do not intrude 94 * on our cache or tlb entries. 95 */ 96 97 #define __LSW 0 98 #define __MSW 1 99 100 /* 101 * The "__xxx" versions of the user access functions do not verify the address 102 * space - it must have been done previously with a separate "access_ok()" 103 * call. 104 */ 105 106 #define __get_user_asm(insn, x, ptr, err) \ 107 do { \ 108 uintptr_t __tmp; \ 109 __typeof__(x) __x; \ 110 __enable_user_access(); \ 111 __asm__ __volatile__ ( \ 112 "1:\n" \ 113 " " insn " %1, %3\n" \ 114 "2:\n" \ 115 " .section .fixup,\"ax\"\n" \ 116 " .balign 4\n" \ 117 "3:\n" \ 118 " li %0, %4\n" \ 119 " li %1, 0\n" \ 120 " jump 2b, %2\n" \ 121 " .previous\n" \ 122 " .section __ex_table,\"a\"\n" \ 123 " .balign " RISCV_SZPTR "\n" \ 124 " " RISCV_PTR " 1b, 3b\n" \ 125 " .previous" \ 126 : "+r" (err), "=&r" (__x), "=r" (__tmp) \ 127 : "m" (*(ptr)), "i" (-EFAULT)); \ 128 __disable_user_access(); \ 129 (x) = __x; \ 130 } while (0) 131 132 #ifdef CONFIG_64BIT 133 #define __get_user_8(x, ptr, err) \ 134 __get_user_asm("ld", x, ptr, err) 135 #else /* !CONFIG_64BIT */ 136 #define __get_user_8(x, ptr, err) \ 137 do { \ 138 u32 __user *__ptr = (u32 __user *)(ptr); \ 139 u32 __lo, __hi; \ 140 uintptr_t __tmp; \ 141 __enable_user_access(); \ 142 __asm__ __volatile__ ( \ 143 "1:\n" \ 144 " lw %1, %4\n" \ 145 "2:\n" \ 146 " lw %2, %5\n" \ 147 "3:\n" \ 148 " .section .fixup,\"ax\"\n" \ 149 " .balign 4\n" \ 150 "4:\n" \ 151 " li %0, %6\n" \ 152 " li %1, 0\n" \ 153 " li %2, 0\n" \ 154 " jump 3b, %3\n" \ 155 " .previous\n" \ 156 " .section __ex_table,\"a\"\n" \ 157 " .balign " RISCV_SZPTR "\n" \ 158 " " RISCV_PTR " 1b, 4b\n" \ 159 " " RISCV_PTR " 2b, 4b\n" \ 160 " .previous" \ 161 : "+r" (err), "=&r" (__lo), "=r" (__hi), \ 162 "=r" (__tmp) \ 163 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]), \ 164 "i" (-EFAULT)); \ 165 __disable_user_access(); \ 166 (x) = (__typeof__(x))((__typeof__((x)-(x)))( \ 167 (((u64)__hi << 32) | __lo))); \ 168 } while (0) 169 #endif /* CONFIG_64BIT */ 170 171 172 /** 173 * __get_user: - Get a simple variable from user space, with less checking. 174 * @x: Variable to store result. 175 * @ptr: Source address, in user space. 176 * 177 * Context: User context only. This function may sleep. 178 * 179 * This macro copies a single simple variable from user space to kernel 180 * space. It supports simple types like char and int, but not larger 181 * data types like structures or arrays. 182 * 183 * @ptr must have pointer-to-simple-variable type, and the result of 184 * dereferencing @ptr must be assignable to @x without a cast. 185 * 186 * Caller must check the pointer with access_ok() before calling this 187 * function. 188 * 189 * Returns zero on success, or -EFAULT on error. 190 * On error, the variable @x is set to zero. 191 */ 192 #define __get_user(x, ptr) \ 193 ({ \ 194 register long __gu_err = 0; \ 195 const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 196 __chk_user_ptr(__gu_ptr); \ 197 switch (sizeof(*__gu_ptr)) { \ 198 case 1: \ 199 __get_user_asm("lb", (x), __gu_ptr, __gu_err); \ 200 break; \ 201 case 2: \ 202 __get_user_asm("lh", (x), __gu_ptr, __gu_err); \ 203 break; \ 204 case 4: \ 205 __get_user_asm("lw", (x), __gu_ptr, __gu_err); \ 206 break; \ 207 case 8: \ 208 __get_user_8((x), __gu_ptr, __gu_err); \ 209 break; \ 210 default: \ 211 BUILD_BUG(); \ 212 } \ 213 __gu_err; \ 214 }) 215 216 /** 217 * get_user: - Get a simple variable from user space. 218 * @x: Variable to store result. 219 * @ptr: Source address, in user space. 220 * 221 * Context: User context only. This function may sleep. 222 * 223 * This macro copies a single simple variable from user space to kernel 224 * space. It supports simple types like char and int, but not larger 225 * data types like structures or arrays. 226 * 227 * @ptr must have pointer-to-simple-variable type, and the result of 228 * dereferencing @ptr must be assignable to @x without a cast. 229 * 230 * Returns zero on success, or -EFAULT on error. 231 * On error, the variable @x is set to zero. 232 */ 233 #define get_user(x, ptr) \ 234 ({ \ 235 const __typeof__(*(ptr)) __user *__p = (ptr); \ 236 might_fault(); \ 237 access_ok(__p, sizeof(*__p)) ? \ 238 __get_user((x), __p) : \ 239 ((x) = 0, -EFAULT); \ 240 }) 241 242 #define __put_user_asm(insn, x, ptr, err) \ 243 do { \ 244 uintptr_t __tmp; \ 245 __typeof__(*(ptr)) __x = x; \ 246 __enable_user_access(); \ 247 __asm__ __volatile__ ( \ 248 "1:\n" \ 249 " " insn " %z3, %2\n" \ 250 "2:\n" \ 251 " .section .fixup,\"ax\"\n" \ 252 " .balign 4\n" \ 253 "3:\n" \ 254 " li %0, %4\n" \ 255 " jump 2b, %1\n" \ 256 " .previous\n" \ 257 " .section __ex_table,\"a\"\n" \ 258 " .balign " RISCV_SZPTR "\n" \ 259 " " RISCV_PTR " 1b, 3b\n" \ 260 " .previous" \ 261 : "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \ 262 : "rJ" (__x), "i" (-EFAULT)); \ 263 __disable_user_access(); \ 264 } while (0) 265 266 #ifdef CONFIG_64BIT 267 #define __put_user_8(x, ptr, err) \ 268 __put_user_asm("sd", x, ptr, err) 269 #else /* !CONFIG_64BIT */ 270 #define __put_user_8(x, ptr, err) \ 271 do { \ 272 u32 __user *__ptr = (u32 __user *)(ptr); \ 273 u64 __x = (__typeof__((x)-(x)))(x); \ 274 uintptr_t __tmp; \ 275 __enable_user_access(); \ 276 __asm__ __volatile__ ( \ 277 "1:\n" \ 278 " sw %z4, %2\n" \ 279 "2:\n" \ 280 " sw %z5, %3\n" \ 281 "3:\n" \ 282 " .section .fixup,\"ax\"\n" \ 283 " .balign 4\n" \ 284 "4:\n" \ 285 " li %0, %6\n" \ 286 " jump 3b, %1\n" \ 287 " .previous\n" \ 288 " .section __ex_table,\"a\"\n" \ 289 " .balign " RISCV_SZPTR "\n" \ 290 " " RISCV_PTR " 1b, 4b\n" \ 291 " " RISCV_PTR " 2b, 4b\n" \ 292 " .previous" \ 293 : "+r" (err), "=r" (__tmp), \ 294 "=m" (__ptr[__LSW]), \ 295 "=m" (__ptr[__MSW]) \ 296 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \ 297 __disable_user_access(); \ 298 } while (0) 299 #endif /* CONFIG_64BIT */ 300 301 302 /** 303 * __put_user: - Write a simple value into user space, with less checking. 304 * @x: Value to copy to user space. 305 * @ptr: Destination address, in user space. 306 * 307 * Context: User context only. This function may sleep. 308 * 309 * This macro copies a single simple value from kernel space to user 310 * space. It supports simple types like char and int, but not larger 311 * data types like structures or arrays. 312 * 313 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 314 * to the result of dereferencing @ptr. 315 * 316 * Caller must check the pointer with access_ok() before calling this 317 * function. 318 * 319 * Returns zero on success, or -EFAULT on error. 320 */ 321 #define __put_user(x, ptr) \ 322 ({ \ 323 register long __pu_err = 0; \ 324 __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 325 __chk_user_ptr(__gu_ptr); \ 326 switch (sizeof(*__gu_ptr)) { \ 327 case 1: \ 328 __put_user_asm("sb", (x), __gu_ptr, __pu_err); \ 329 break; \ 330 case 2: \ 331 __put_user_asm("sh", (x), __gu_ptr, __pu_err); \ 332 break; \ 333 case 4: \ 334 __put_user_asm("sw", (x), __gu_ptr, __pu_err); \ 335 break; \ 336 case 8: \ 337 __put_user_8((x), __gu_ptr, __pu_err); \ 338 break; \ 339 default: \ 340 BUILD_BUG(); \ 341 } \ 342 __pu_err; \ 343 }) 344 345 /** 346 * put_user: - Write a simple value into user space. 347 * @x: Value to copy to user space. 348 * @ptr: Destination address, in user space. 349 * 350 * Context: User context only. This function may sleep. 351 * 352 * This macro copies a single simple value from kernel space to user 353 * space. It supports simple types like char and int, but not larger 354 * data types like structures or arrays. 355 * 356 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 357 * to the result of dereferencing @ptr. 358 * 359 * Returns zero on success, or -EFAULT on error. 360 */ 361 #define put_user(x, ptr) \ 362 ({ \ 363 __typeof__(*(ptr)) __user *__p = (ptr); \ 364 might_fault(); \ 365 access_ok(__p, sizeof(*__p)) ? \ 366 __put_user((x), __p) : \ 367 -EFAULT; \ 368 }) 369 370 371 extern unsigned long __must_check __asm_copy_to_user(void __user *to, 372 const void *from, unsigned long n); 373 extern unsigned long __must_check __asm_copy_from_user(void *to, 374 const void __user *from, unsigned long n); 375 376 static inline unsigned long 377 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 378 { 379 return __asm_copy_from_user(to, from, n); 380 } 381 382 static inline unsigned long 383 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 384 { 385 return __asm_copy_to_user(to, from, n); 386 } 387 388 extern long strncpy_from_user(char *dest, const char __user *src, long count); 389 390 extern long __must_check strlen_user(const char __user *str); 391 extern long __must_check strnlen_user(const char __user *str, long n); 392 393 extern 394 unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 395 396 static inline 397 unsigned long __must_check clear_user(void __user *to, unsigned long n) 398 { 399 might_fault(); 400 return access_ok(to, n) ? 401 __clear_user(to, n) : n; 402 } 403 404 /* 405 * Atomic compare-and-exchange, but with a fixup for userspace faults. Faults 406 * will set "err" to -EFAULT, while successful accesses return the previous 407 * value. 408 */ 409 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb) \ 410 ({ \ 411 __typeof__(ptr) __ptr = (ptr); \ 412 __typeof__(*(ptr)) __old = (old); \ 413 __typeof__(*(ptr)) __new = (new); \ 414 __typeof__(*(ptr)) __ret; \ 415 __typeof__(err) __err = 0; \ 416 register unsigned int __rc; \ 417 __enable_user_access(); \ 418 switch (size) { \ 419 case 4: \ 420 __asm__ __volatile__ ( \ 421 "0:\n" \ 422 " lr.w" #scb " %[ret], %[ptr]\n" \ 423 " bne %[ret], %z[old], 1f\n" \ 424 " sc.w" #lrb " %[rc], %z[new], %[ptr]\n" \ 425 " bnez %[rc], 0b\n" \ 426 "1:\n" \ 427 ".section .fixup,\"ax\"\n" \ 428 ".balign 4\n" \ 429 "2:\n" \ 430 " li %[err], %[efault]\n" \ 431 " jump 1b, %[rc]\n" \ 432 ".previous\n" \ 433 ".section __ex_table,\"a\"\n" \ 434 ".balign " RISCV_SZPTR "\n" \ 435 " " RISCV_PTR " 1b, 2b\n" \ 436 ".previous\n" \ 437 : [ret] "=&r" (__ret), \ 438 [rc] "=&r" (__rc), \ 439 [ptr] "+A" (*__ptr), \ 440 [err] "=&r" (__err) \ 441 : [old] "rJ" (__old), \ 442 [new] "rJ" (__new), \ 443 [efault] "i" (-EFAULT)); \ 444 break; \ 445 case 8: \ 446 __asm__ __volatile__ ( \ 447 "0:\n" \ 448 " lr.d" #scb " %[ret], %[ptr]\n" \ 449 " bne %[ret], %z[old], 1f\n" \ 450 " sc.d" #lrb " %[rc], %z[new], %[ptr]\n" \ 451 " bnez %[rc], 0b\n" \ 452 "1:\n" \ 453 ".section .fixup,\"ax\"\n" \ 454 ".balign 4\n" \ 455 "2:\n" \ 456 " li %[err], %[efault]\n" \ 457 " jump 1b, %[rc]\n" \ 458 ".previous\n" \ 459 ".section __ex_table,\"a\"\n" \ 460 ".balign " RISCV_SZPTR "\n" \ 461 " " RISCV_PTR " 1b, 2b\n" \ 462 ".previous\n" \ 463 : [ret] "=&r" (__ret), \ 464 [rc] "=&r" (__rc), \ 465 [ptr] "+A" (*__ptr), \ 466 [err] "=&r" (__err) \ 467 : [old] "rJ" (__old), \ 468 [new] "rJ" (__new), \ 469 [efault] "i" (-EFAULT)); \ 470 break; \ 471 default: \ 472 BUILD_BUG(); \ 473 } \ 474 __disable_user_access(); \ 475 (err) = __err; \ 476 __ret; \ 477 }) 478 479 #else /* CONFIG_MMU */ 480 #include <asm-generic/uaccess.h> 481 #endif /* CONFIG_MMU */ 482 #endif /* _ASM_RISCV_UACCESS_H */ 483