1/* 2 * include/asm-xtensa/uaccess.h 3 * 4 * User space memory access functions 5 * 6 * These routines provide basic accessing functions to the user memory 7 * space for the kernel. This header file provides fuctions such as: 8 * 9 * This file is subject to the terms and conditions of the GNU General Public 10 * License. See the file "COPYING" in the main directory of this archive 11 * for more details. 12 * 13 * Copyright (C) 2001 - 2005 Tensilica Inc. 14 */ 15 16#ifndef _XTENSA_UACCESS_H 17#define _XTENSA_UACCESS_H 18 19#include <linux/errno.h> 20 21#define VERIFY_READ 0 22#define VERIFY_WRITE 1 23 24#ifdef __ASSEMBLY__ 25 26#include <asm/current.h> 27#include <asm/asm-offsets.h> 28#include <asm/processor.h> 29#include <asm/types.h> 30 31/* 32 * These assembly macros mirror the C macros that follow below. They 33 * should always have identical functionality. See 34 * arch/xtensa/kernel/sys.S for usage. 35 */ 36 37#define KERNEL_DS 0 38#define USER_DS 1 39 40#define get_ds (KERNEL_DS) 41 42/* 43 * get_fs reads current->thread.current_ds into a register. 44 * On Entry: 45 * <ad> anything 46 * <sp> stack 47 * On Exit: 48 * <ad> contains current->thread.current_ds 49 */ 50 .macro get_fs ad, sp 51 GET_CURRENT(\ad,\sp) 52 l32i \ad, \ad, THREAD_CURRENT_DS 53 .endm 54 55/* 56 * set_fs sets current->thread.current_ds to some value. 57 * On Entry: 58 * <at> anything (temp register) 59 * <av> value to write 60 * <sp> stack 61 * On Exit: 62 * <at> destroyed (actually, current) 63 * <av> preserved, value to write 64 */ 65 .macro set_fs at, av, sp 66 GET_CURRENT(\at,\sp) 67 s32i \av, \at, THREAD_CURRENT_DS 68 .endm 69 70/* 71 * kernel_ok determines whether we should bypass addr/size checking. 72 * See the equivalent C-macro version below for clarity. 73 * On success, kernel_ok branches to a label indicated by parameter 74 * <success>. This implies that the macro falls through to the next 75 * insruction on an error. 76 * 77 * Note that while this macro can be used independently, we designed 78 * in for optimal use in the access_ok macro below (i.e., we fall 79 * through on error). 80 * 81 * On Entry: 82 * <at> anything (temp register) 83 * <success> label to branch to on success; implies 84 * fall-through macro on error 85 * <sp> stack pointer 86 * On Exit: 87 * <at> destroyed (actually, current->thread.current_ds) 88 */ 89 90#if ((KERNEL_DS != 0) || (USER_DS == 0)) 91# error Assembly macro kernel_ok fails 92#endif 93 .macro kernel_ok at, sp, success 94 get_fs \at, \sp 95 beqz \at, \success 96 .endm 97 98/* 99 * user_ok determines whether the access to user-space memory is allowed. 100 * See the equivalent C-macro version below for clarity. 101 * 102 * On error, user_ok branches to a label indicated by parameter 103 * <error>. This implies that the macro falls through to the next 104 * instruction on success. 105 * 106 * Note that while this macro can be used independently, we designed 107 * in for optimal use in the access_ok macro below (i.e., we fall 108 * through on success). 109 * 110 * On Entry: 111 * <aa> register containing memory address 112 * <as> register containing memory size 113 * <at> temp register 114 * <error> label to branch to on error; implies fall-through 115 * macro on success 116 * On Exit: 117 * <aa> preserved 118 * <as> preserved 119 * <at> destroyed (actually, (TASK_SIZE + 1 - size)) 120 */ 121 .macro user_ok aa, as, at, error 122 movi \at, __XTENSA_UL_CONST(TASK_SIZE) 123 bgeu \as, \at, \error 124 sub \at, \at, \as 125 bgeu \aa, \at, \error 126 .endm 127 128/* 129 * access_ok determines whether a memory access is allowed. See the 130 * equivalent C-macro version below for clarity. 131 * 132 * On error, access_ok branches to a label indicated by parameter 133 * <error>. This implies that the macro falls through to the next 134 * instruction on success. 135 * 136 * Note that we assume success is the common case, and we optimize the 137 * branch fall-through case on success. 138 * 139 * On Entry: 140 * <aa> register containing memory address 141 * <as> register containing memory size 142 * <at> temp register 143 * <sp> 144 * <error> label to branch to on error; implies fall-through 145 * macro on success 146 * On Exit: 147 * <aa> preserved 148 * <as> preserved 149 * <at> destroyed 150 */ 151 .macro access_ok aa, as, at, sp, error 152 kernel_ok \at, \sp, .Laccess_ok_\@ 153 user_ok \aa, \as, \at, \error 154.Laccess_ok_\@: 155 .endm 156 157#else /* __ASSEMBLY__ not defined */ 158 159#include <linux/sched.h> 160#include <asm/types.h> 161 162/* 163 * The fs value determines whether argument validity checking should 164 * be performed or not. If get_fs() == USER_DS, checking is 165 * performed, with get_fs() == KERNEL_DS, checking is bypassed. 166 * 167 * For historical reasons (Data Segment Register?), these macros are 168 * grossly misnamed. 169 */ 170 171#define KERNEL_DS ((mm_segment_t) { 0 }) 172#define USER_DS ((mm_segment_t) { 1 }) 173 174#define get_ds() (KERNEL_DS) 175#define get_fs() (current->thread.current_ds) 176#define set_fs(val) (current->thread.current_ds = (val)) 177 178#define segment_eq(a,b) ((a).seg == (b).seg) 179 180#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS)) 181#define __user_ok(addr,size) (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size))) 182#define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size))) 183#define access_ok(type,addr,size) __access_ok((unsigned long)(addr),(size)) 184 185/* 186 * These are the main single-value transfer routines. They 187 * automatically use the right size if we just have the right pointer 188 * type. 189 * 190 * This gets kind of ugly. We want to return _two_ values in 191 * "get_user()" and yet we don't want to do any pointers, because that 192 * is too much of a performance impact. Thus we have a few rather ugly 193 * macros here, and hide all the uglyness from the user. 194 * 195 * Careful to not 196 * (a) re-use the arguments for side effects (sizeof is ok) 197 * (b) require any knowledge of processes at this stage 198 */ 199#define put_user(x,ptr) __put_user_check((x),(ptr),sizeof(*(ptr))) 200#define get_user(x,ptr) __get_user_check((x),(ptr),sizeof(*(ptr))) 201 202/* 203 * The "__xxx" versions of the user access functions are versions that 204 * do not verify the address space, that must have been done previously 205 * with a separate "access_ok()" call (this is used when we do multiple 206 * accesses to the same area of user memory). 207 */ 208#define __put_user(x,ptr) __put_user_nocheck((x),(ptr),sizeof(*(ptr))) 209#define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr))) 210 211 212extern long __put_user_bad(void); 213 214#define __put_user_nocheck(x,ptr,size) \ 215({ \ 216 long __pu_err; \ 217 __put_user_size((x),(ptr),(size),__pu_err); \ 218 __pu_err; \ 219}) 220 221#define __put_user_check(x,ptr,size) \ 222({ \ 223 long __pu_err = -EFAULT; \ 224 __typeof__(*(ptr)) *__pu_addr = (ptr); \ 225 if (access_ok(VERIFY_WRITE,__pu_addr,size)) \ 226 __put_user_size((x),__pu_addr,(size),__pu_err); \ 227 __pu_err; \ 228}) 229 230#define __put_user_size(x,ptr,size,retval) \ 231do { \ 232 int __cb; \ 233 retval = 0; \ 234 switch (size) { \ 235 case 1: __put_user_asm(x,ptr,retval,1,"s8i",__cb); break; \ 236 case 2: __put_user_asm(x,ptr,retval,2,"s16i",__cb); break; \ 237 case 4: __put_user_asm(x,ptr,retval,4,"s32i",__cb); break; \ 238 case 8: { \ 239 __typeof__(*ptr) __v64 = x; \ 240 retval = __copy_to_user(ptr,&__v64,8); \ 241 break; \ 242 } \ 243 default: __put_user_bad(); \ 244 } \ 245} while (0) 246 247 248/* 249 * Consider a case of a user single load/store would cause both an 250 * unaligned exception and an MMU-related exception (unaligned 251 * exceptions happen first): 252 * 253 * User code passes a bad variable ptr to a system call. 254 * Kernel tries to access the variable. 255 * Unaligned exception occurs. 256 * Unaligned exception handler tries to make aligned accesses. 257 * Double exception occurs for MMU-related cause (e.g., page not mapped). 258 * do_page_fault() thinks the fault address belongs to the kernel, not the 259 * user, and panics. 260 * 261 * The kernel currently prohibits user unaligned accesses. We use the 262 * __check_align_* macros to check for unaligned addresses before 263 * accessing user space so we don't crash the kernel. Both 264 * __put_user_asm and __get_user_asm use these alignment macros, so 265 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in 266 * sync. 267 */ 268 269#define __check_align_1 "" 270 271#define __check_align_2 \ 272 " _bbci.l %3, 0, 1f \n" \ 273 " movi %0, %4 \n" \ 274 " _j 2f \n" 275 276#define __check_align_4 \ 277 " _bbsi.l %3, 0, 0f \n" \ 278 " _bbci.l %3, 1, 1f \n" \ 279 "0: movi %0, %4 \n" \ 280 " _j 2f \n" 281 282 283/* 284 * We don't tell gcc that we are accessing memory, but this is OK 285 * because we do not write to any memory gcc knows about, so there 286 * are no aliasing issues. 287 * 288 * WARNING: If you modify this macro at all, verify that the 289 * __check_align_* macros still work. 290 */ 291#define __put_user_asm(x, addr, err, align, insn, cb) \ 292 __asm__ __volatile__( \ 293 __check_align_##align \ 294 "1: "insn" %2, %3, 0 \n" \ 295 "2: \n" \ 296 " .section .fixup,\"ax\" \n" \ 297 " .align 4 \n" \ 298 "4: \n" \ 299 " .long 2b \n" \ 300 "5: \n" \ 301 " l32r %1, 4b \n" \ 302 " movi %0, %4 \n" \ 303 " jx %1 \n" \ 304 " .previous \n" \ 305 " .section __ex_table,\"a\" \n" \ 306 " .long 1b, 5b \n" \ 307 " .previous" \ 308 :"=r" (err), "=r" (cb) \ 309 :"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err)) 310 311#define __get_user_nocheck(x,ptr,size) \ 312({ \ 313 long __gu_err, __gu_val; \ 314 __get_user_size(__gu_val,(ptr),(size),__gu_err); \ 315 (x) = (__typeof__(*(ptr)))__gu_val; \ 316 __gu_err; \ 317}) 318 319#define __get_user_check(x,ptr,size) \ 320({ \ 321 long __gu_err = -EFAULT, __gu_val = 0; \ 322 const __typeof__(*(ptr)) *__gu_addr = (ptr); \ 323 if (access_ok(VERIFY_READ,__gu_addr,size)) \ 324 __get_user_size(__gu_val,__gu_addr,(size),__gu_err); \ 325 (x) = (__typeof__(*(ptr)))__gu_val; \ 326 __gu_err; \ 327}) 328 329extern long __get_user_bad(void); 330 331#define __get_user_size(x,ptr,size,retval) \ 332do { \ 333 int __cb; \ 334 retval = 0; \ 335 switch (size) { \ 336 case 1: __get_user_asm(x,ptr,retval,1,"l8ui",__cb); break; \ 337 case 2: __get_user_asm(x,ptr,retval,2,"l16ui",__cb); break; \ 338 case 4: __get_user_asm(x,ptr,retval,4,"l32i",__cb); break; \ 339 case 8: retval = __copy_from_user(&x,ptr,8); break; \ 340 default: (x) = __get_user_bad(); \ 341 } \ 342} while (0) 343 344 345/* 346 * WARNING: If you modify this macro at all, verify that the 347 * __check_align_* macros still work. 348 */ 349#define __get_user_asm(x, addr, err, align, insn, cb) \ 350 __asm__ __volatile__( \ 351 __check_align_##align \ 352 "1: "insn" %2, %3, 0 \n" \ 353 "2: \n" \ 354 " .section .fixup,\"ax\" \n" \ 355 " .align 4 \n" \ 356 "4: \n" \ 357 " .long 2b \n" \ 358 "5: \n" \ 359 " l32r %1, 4b \n" \ 360 " movi %2, 0 \n" \ 361 " movi %0, %4 \n" \ 362 " jx %1 \n" \ 363 " .previous \n" \ 364 " .section __ex_table,\"a\" \n" \ 365 " .long 1b, 5b \n" \ 366 " .previous" \ 367 :"=r" (err), "=r" (cb), "=r" (x) \ 368 :"r" (addr), "i" (-EFAULT), "0" (err)) 369 370 371/* 372 * Copy to/from user space 373 */ 374 375/* 376 * We use a generic, arbitrary-sized copy subroutine. The Xtensa 377 * architecture would cause heavy code bloat if we tried to inline 378 * these functions and provide __constant_copy_* equivalents like the 379 * i386 versions. __xtensa_copy_user is quite efficient. See the 380 * .fixup section of __xtensa_copy_user for a discussion on the 381 * X_zeroing equivalents for Xtensa. 382 */ 383 384extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n); 385#define __copy_user(to,from,size) __xtensa_copy_user(to,from,size) 386 387 388static inline unsigned long 389__generic_copy_from_user_nocheck(void *to, const void *from, unsigned long n) 390{ 391 return __copy_user(to,from,n); 392} 393 394static inline unsigned long 395__generic_copy_to_user_nocheck(void *to, const void *from, unsigned long n) 396{ 397 return __copy_user(to,from,n); 398} 399 400static inline unsigned long 401__generic_copy_to_user(void *to, const void *from, unsigned long n) 402{ 403 prefetch(from); 404 if (access_ok(VERIFY_WRITE, to, n)) 405 return __copy_user(to,from,n); 406 return n; 407} 408 409static inline unsigned long 410__generic_copy_from_user(void *to, const void *from, unsigned long n) 411{ 412 prefetchw(to); 413 if (access_ok(VERIFY_READ, from, n)) 414 return __copy_user(to,from,n); 415 else 416 memset(to, 0, n); 417 return n; 418} 419 420#define copy_to_user(to,from,n) __generic_copy_to_user((to),(from),(n)) 421#define copy_from_user(to,from,n) __generic_copy_from_user((to),(from),(n)) 422#define __copy_to_user(to,from,n) __generic_copy_to_user_nocheck((to),(from),(n)) 423#define __copy_from_user(to,from,n) __generic_copy_from_user_nocheck((to),(from),(n)) 424#define __copy_to_user_inatomic __copy_to_user 425#define __copy_from_user_inatomic __copy_from_user 426 427 428/* 429 * We need to return the number of bytes not cleared. Our memset() 430 * returns zero if a problem occurs while accessing user-space memory. 431 * In that event, return no memory cleared. Otherwise, zero for 432 * success. 433 */ 434 435static inline unsigned long 436__xtensa_clear_user(void *addr, unsigned long size) 437{ 438 if ( ! memset(addr, 0, size) ) 439 return size; 440 return 0; 441} 442 443static inline unsigned long 444clear_user(void *addr, unsigned long size) 445{ 446 if (access_ok(VERIFY_WRITE, addr, size)) 447 return __xtensa_clear_user(addr, size); 448 return size ? -EFAULT : 0; 449} 450 451#define __clear_user __xtensa_clear_user 452 453 454extern long __strncpy_user(char *, const char *, long); 455#define __strncpy_from_user __strncpy_user 456 457static inline long 458strncpy_from_user(char *dst, const char *src, long count) 459{ 460 if (access_ok(VERIFY_READ, src, 1)) 461 return __strncpy_from_user(dst, src, count); 462 return -EFAULT; 463} 464 465 466#define strlen_user(str) strnlen_user((str), TASK_SIZE - 1) 467 468/* 469 * Return the size of a string (including the ending 0!) 470 */ 471extern long __strnlen_user(const char *, long); 472 473static inline long strnlen_user(const char *str, long len) 474{ 475 unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1; 476 477 if ((unsigned long)str > top) 478 return 0; 479 return __strnlen_user(str, len); 480} 481 482 483struct exception_table_entry 484{ 485 unsigned long insn, fixup; 486}; 487 488/* Returns 0 if exception not found and fixup.unit otherwise. */ 489 490extern unsigned long search_exception_table(unsigned long addr); 491extern void sort_exception_table(void); 492 493/* Returns the new pc */ 494#define fixup_exception(map_reg, fixup_unit, pc) \ 495({ \ 496 fixup_unit; \ 497}) 498 499#endif /* __ASSEMBLY__ */ 500#endif /* _XTENSA_UACCESS_H */ 501