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Linux/arch/arm/include/asm/uaccess.h

  1 /*
  2  *  arch/arm/include/asm/uaccess.h
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  */
  8 #ifndef _ASMARM_UACCESS_H
  9 #define _ASMARM_UACCESS_H
 10 
 11 /*
 12  * User space memory access functions
 13  */
 14 #include <linux/string.h>
 15 #include <linux/thread_info.h>
 16 #include <asm/errno.h>
 17 #include <asm/memory.h>
 18 #include <asm/domain.h>
 19 #include <asm/unified.h>
 20 #include <asm/compiler.h>
 21 
 22 #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 23 #include <asm-generic/uaccess-unaligned.h>
 24 #else
 25 #define __get_user_unaligned __get_user
 26 #define __put_user_unaligned __put_user
 27 #endif
 28 
 29 #define VERIFY_READ 0
 30 #define VERIFY_WRITE 1
 31 
 32 /*
 33  * The exception table consists of pairs of addresses: the first is the
 34  * address of an instruction that is allowed to fault, and the second is
 35  * the address at which the program should continue.  No registers are
 36  * modified, so it is entirely up to the continuation code to figure out
 37  * what to do.
 38  *
 39  * All the routines below use bits of fixup code that are out of line
 40  * with the main instruction path.  This means when everything is well,
 41  * we don't even have to jump over them.  Further, they do not intrude
 42  * on our cache or tlb entries.
 43  */
 44 
 45 struct exception_table_entry
 46 {
 47         unsigned long insn, fixup;
 48 };
 49 
 50 extern int fixup_exception(struct pt_regs *regs);
 51 
 52 /*
 53  * These two are intentionally not defined anywhere - if the kernel
 54  * code generates any references to them, that's a bug.
 55  */
 56 extern int __get_user_bad(void);
 57 extern int __put_user_bad(void);
 58 
 59 /*
 60  * Note that this is actually 0x1,0000,0000
 61  */
 62 #define KERNEL_DS       0x00000000
 63 #define get_ds()        (KERNEL_DS)
 64 
 65 #ifdef CONFIG_MMU
 66 
 67 #define USER_DS         TASK_SIZE
 68 #define get_fs()        (current_thread_info()->addr_limit)
 69 
 70 static inline void set_fs(mm_segment_t fs)
 71 {
 72         current_thread_info()->addr_limit = fs;
 73         modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
 74 }
 75 
 76 #define segment_eq(a,b) ((a) == (b))
 77 
 78 #define __addr_ok(addr) ({ \
 79         unsigned long flag; \
 80         __asm__("cmp %2, %0; movlo %0, #0" \
 81                 : "=&r" (flag) \
 82                 : "" (current_thread_info()->addr_limit), "r" (addr) \
 83                 : "cc"); \
 84         (flag == 0); })
 85 
 86 /* We use 33-bit arithmetic here... */
 87 #define __range_ok(addr,size) ({ \
 88         unsigned long flag, roksum; \
 89         __chk_user_ptr(addr);   \
 90         __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
 91                 : "=&r" (flag), "=&r" (roksum) \
 92                 : "r" (addr), "Ir" (size), "" (current_thread_info()->addr_limit) \
 93                 : "cc"); \
 94         flag; })
 95 
 96 /*
 97  * Single-value transfer routines.  They automatically use the right
 98  * size if we just have the right pointer type.  Note that the functions
 99  * which read from user space (*get_*) need to take care not to leak
100  * kernel data even if the calling code is buggy and fails to check
101  * the return value.  This means zeroing out the destination variable
102  * or buffer on error.  Normally this is done out of line by the
103  * fixup code, but there are a few places where it intrudes on the
104  * main code path.  When we only write to user space, there is no
105  * problem.
106  */
107 extern int __get_user_1(void *);
108 extern int __get_user_2(void *);
109 extern int __get_user_4(void *);
110 extern int __get_user_32t_8(void *);
111 extern int __get_user_8(void *);
112 extern int __get_user_64t_1(void *);
113 extern int __get_user_64t_2(void *);
114 extern int __get_user_64t_4(void *);
115 
116 #define __GUP_CLOBBER_1 "lr", "cc"
117 #ifdef CONFIG_CPU_USE_DOMAINS
118 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
119 #else
120 #define __GUP_CLOBBER_2 "lr", "cc"
121 #endif
122 #define __GUP_CLOBBER_4 "lr", "cc"
123 #define __GUP_CLOBBER_32t_8 "lr", "cc"
124 #define __GUP_CLOBBER_8 "lr", "cc"
125 
126 #define __get_user_x(__r2,__p,__e,__l,__s)                              \
127            __asm__ __volatile__ (                                       \
128                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
129                 __asmeq("%3", "r1")                                     \
130                 "bl     __get_user_" #__s                               \
131                 : "=&r" (__e), "=r" (__r2)                              \
132                 : "" (__p), "r" (__l)                                  \
133                 : __GUP_CLOBBER_##__s)
134 
135 /* narrowing a double-word get into a single 32bit word register: */
136 #ifdef __ARMEB__
137 #define __get_user_x_32t(__r2, __p, __e, __l, __s)                              \
138         __get_user_x(__r2, __p, __e, __l, 32t_8)
139 #else
140 #define __get_user_x_32t __get_user_x
141 #endif
142 
143 /*
144  * storing result into proper least significant word of 64bit target var,
145  * different only for big endian case where 64 bit __r2 lsw is r3:
146  */
147 #ifdef __ARMEB__
148 #define __get_user_x_64t(__r2, __p, __e, __l, __s)                      \
149            __asm__ __volatile__ (                                       \
150                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
151                 __asmeq("%3", "r1")                                     \
152                 "bl     __get_user_64t_" #__s                           \
153                 : "=&r" (__e), "=r" (__r2)                              \
154                 : "" (__p), "r" (__l)                                  \
155                 : __GUP_CLOBBER_##__s)
156 #else
157 #define __get_user_x_64t __get_user_x
158 #endif
159 
160 
161 #define __get_user_check(x,p)                                                   \
162         ({                                                              \
163                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
164                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
165                 register typeof(x) __r2 asm("r2");                      \
166                 register unsigned long __l asm("r1") = __limit;         \
167                 register int __e asm("r0");                             \
168                 switch (sizeof(*(__p))) {                               \
169                 case 1:                                                 \
170                         if (sizeof((x)) >= 8)                           \
171                                 __get_user_x_64t(__r2, __p, __e, __l, 1); \
172                         else                                            \
173                                 __get_user_x(__r2, __p, __e, __l, 1);   \
174                         break;                                          \
175                 case 2:                                                 \
176                         if (sizeof((x)) >= 8)                           \
177                                 __get_user_x_64t(__r2, __p, __e, __l, 2); \
178                         else                                            \
179                                 __get_user_x(__r2, __p, __e, __l, 2);   \
180                         break;                                          \
181                 case 4:                                                 \
182                         if (sizeof((x)) >= 8)                           \
183                                 __get_user_x_64t(__r2, __p, __e, __l, 4); \
184                         else                                            \
185                                 __get_user_x(__r2, __p, __e, __l, 4);   \
186                         break;                                          \
187                 case 8:                                                 \
188                         if (sizeof((x)) < 8)                            \
189                                 __get_user_x_32t(__r2, __p, __e, __l, 4); \
190                         else                                            \
191                                 __get_user_x(__r2, __p, __e, __l, 8);   \
192                         break;                                          \
193                 default: __e = __get_user_bad(); break;                 \
194                 }                                                       \
195                 x = (typeof(*(p))) __r2;                                \
196                 __e;                                                    \
197         })
198 
199 #define get_user(x,p)                                                   \
200         ({                                                              \
201                 might_fault();                                          \
202                 __get_user_check(x,p);                                  \
203          })
204 
205 extern int __put_user_1(void *, unsigned int);
206 extern int __put_user_2(void *, unsigned int);
207 extern int __put_user_4(void *, unsigned int);
208 extern int __put_user_8(void *, unsigned long long);
209 
210 #define __put_user_x(__r2,__p,__e,__l,__s)                              \
211            __asm__ __volatile__ (                                       \
212                 __asmeq("%0", "r0") __asmeq("%2", "r2")                 \
213                 __asmeq("%3", "r1")                                     \
214                 "bl     __put_user_" #__s                               \
215                 : "=&r" (__e)                                           \
216                 : "" (__p), "r" (__r2), "r" (__l)                      \
217                 : "ip", "lr", "cc")
218 
219 #define __put_user_check(x,p)                                                   \
220         ({                                                              \
221                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
222                 const typeof(*(p)) __user *__tmp_p = (p);               \
223                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
224                 register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \
225                 register unsigned long __l asm("r1") = __limit;         \
226                 register int __e asm("r0");                             \
227                 switch (sizeof(*(__p))) {                               \
228                 case 1:                                                 \
229                         __put_user_x(__r2, __p, __e, __l, 1);           \
230                         break;                                          \
231                 case 2:                                                 \
232                         __put_user_x(__r2, __p, __e, __l, 2);           \
233                         break;                                          \
234                 case 4:                                                 \
235                         __put_user_x(__r2, __p, __e, __l, 4);           \
236                         break;                                          \
237                 case 8:                                                 \
238                         __put_user_x(__r2, __p, __e, __l, 8);           \
239                         break;                                          \
240                 default: __e = __put_user_bad(); break;                 \
241                 }                                                       \
242                 __e;                                                    \
243         })
244 
245 #define put_user(x,p)                                                   \
246         ({                                                              \
247                 might_fault();                                          \
248                 __put_user_check(x,p);                                  \
249          })
250 
251 #else /* CONFIG_MMU */
252 
253 /*
254  * uClinux has only one addr space, so has simplified address limits.
255  */
256 #define USER_DS                 KERNEL_DS
257 
258 #define segment_eq(a,b)         (1)
259 #define __addr_ok(addr)         ((void)(addr),1)
260 #define __range_ok(addr,size)   ((void)(addr),0)
261 #define get_fs()                (KERNEL_DS)
262 
263 static inline void set_fs(mm_segment_t fs)
264 {
265 }
266 
267 #define get_user(x,p)   __get_user(x,p)
268 #define put_user(x,p)   __put_user(x,p)
269 
270 #endif /* CONFIG_MMU */
271 
272 #define access_ok(type,addr,size)       (__range_ok(addr,size) == 0)
273 
274 #define user_addr_max() \
275         (segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs())
276 
277 /*
278  * The "__xxx" versions of the user access functions do not verify the
279  * address space - it must have been done previously with a separate
280  * "access_ok()" call.
281  *
282  * The "xxx_error" versions set the third argument to EFAULT if an
283  * error occurs, and leave it unchanged on success.  Note that these
284  * versions are void (ie, don't return a value as such).
285  */
286 #define __get_user(x,ptr)                                               \
287 ({                                                                      \
288         long __gu_err = 0;                                              \
289         __get_user_err((x),(ptr),__gu_err);                             \
290         __gu_err;                                                       \
291 })
292 
293 #define __get_user_error(x,ptr,err)                                     \
294 ({                                                                      \
295         __get_user_err((x),(ptr),err);                                  \
296         (void) 0;                                                       \
297 })
298 
299 #define __get_user_err(x,ptr,err)                                       \
300 do {                                                                    \
301         unsigned long __gu_addr = (unsigned long)(ptr);                 \
302         unsigned long __gu_val;                                         \
303         __chk_user_ptr(ptr);                                            \
304         might_fault();                                                  \
305         switch (sizeof(*(ptr))) {                                       \
306         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
307         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
308         case 4: __get_user_asm_word(__gu_val,__gu_addr,err);    break;  \
309         default: (__gu_val) = __get_user_bad();                         \
310         }                                                               \
311         (x) = (__typeof__(*(ptr)))__gu_val;                             \
312 } while (0)
313 
314 #define __get_user_asm_byte(x,addr,err)                         \
315         __asm__ __volatile__(                                   \
316         "1:     " TUSER(ldrb) " %1,[%2],#0\n"                   \
317         "2:\n"                                                  \
318         "       .pushsection .fixup,\"ax\"\n"                   \
319         "       .align  2\n"                                    \
320         "3:     mov     %0, %3\n"                               \
321         "       mov     %1, #0\n"                               \
322         "       b       2b\n"                                   \
323         "       .popsection\n"                                  \
324         "       .pushsection __ex_table,\"a\"\n"                \
325         "       .align  3\n"                                    \
326         "       .long   1b, 3b\n"                               \
327         "       .popsection"                                    \
328         : "+r" (err), "=&r" (x)                                 \
329         : "r" (addr), "i" (-EFAULT)                             \
330         : "cc")
331 
332 #ifndef __ARMEB__
333 #define __get_user_asm_half(x,__gu_addr,err)                    \
334 ({                                                              \
335         unsigned long __b1, __b2;                               \
336         __get_user_asm_byte(__b1, __gu_addr, err);              \
337         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
338         (x) = __b1 | (__b2 << 8);                               \
339 })
340 #else
341 #define __get_user_asm_half(x,__gu_addr,err)                    \
342 ({                                                              \
343         unsigned long __b1, __b2;                               \
344         __get_user_asm_byte(__b1, __gu_addr, err);              \
345         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
346         (x) = (__b1 << 8) | __b2;                               \
347 })
348 #endif
349 
350 #define __get_user_asm_word(x,addr,err)                         \
351         __asm__ __volatile__(                                   \
352         "1:     " TUSER(ldr) "  %1,[%2],#0\n"                   \
353         "2:\n"                                                  \
354         "       .pushsection .fixup,\"ax\"\n"                   \
355         "       .align  2\n"                                    \
356         "3:     mov     %0, %3\n"                               \
357         "       mov     %1, #0\n"                               \
358         "       b       2b\n"                                   \
359         "       .popsection\n"                                  \
360         "       .pushsection __ex_table,\"a\"\n"                \
361         "       .align  3\n"                                    \
362         "       .long   1b, 3b\n"                               \
363         "       .popsection"                                    \
364         : "+r" (err), "=&r" (x)                                 \
365         : "r" (addr), "i" (-EFAULT)                             \
366         : "cc")
367 
368 #define __put_user(x,ptr)                                               \
369 ({                                                                      \
370         long __pu_err = 0;                                              \
371         __put_user_err((x),(ptr),__pu_err);                             \
372         __pu_err;                                                       \
373 })
374 
375 #define __put_user_error(x,ptr,err)                                     \
376 ({                                                                      \
377         __put_user_err((x),(ptr),err);                                  \
378         (void) 0;                                                       \
379 })
380 
381 #define __put_user_err(x,ptr,err)                                       \
382 do {                                                                    \
383         unsigned long __pu_addr = (unsigned long)(ptr);                 \
384         __typeof__(*(ptr)) __pu_val = (x);                              \
385         __chk_user_ptr(ptr);                                            \
386         might_fault();                                                  \
387         switch (sizeof(*(ptr))) {                                       \
388         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
389         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \
390         case 4: __put_user_asm_word(__pu_val,__pu_addr,err);    break;  \
391         case 8: __put_user_asm_dword(__pu_val,__pu_addr,err);   break;  \
392         default: __put_user_bad();                                      \
393         }                                                               \
394 } while (0)
395 
396 #define __put_user_asm_byte(x,__pu_addr,err)                    \
397         __asm__ __volatile__(                                   \
398         "1:     " TUSER(strb) " %1,[%2],#0\n"                   \
399         "2:\n"                                                  \
400         "       .pushsection .fixup,\"ax\"\n"                   \
401         "       .align  2\n"                                    \
402         "3:     mov     %0, %3\n"                               \
403         "       b       2b\n"                                   \
404         "       .popsection\n"                                  \
405         "       .pushsection __ex_table,\"a\"\n"                \
406         "       .align  3\n"                                    \
407         "       .long   1b, 3b\n"                               \
408         "       .popsection"                                    \
409         : "+r" (err)                                            \
410         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
411         : "cc")
412 
413 #ifndef __ARMEB__
414 #define __put_user_asm_half(x,__pu_addr,err)                    \
415 ({                                                              \
416         unsigned long __temp = (unsigned long)(x);              \
417         __put_user_asm_byte(__temp, __pu_addr, err);            \
418         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
419 })
420 #else
421 #define __put_user_asm_half(x,__pu_addr,err)                    \
422 ({                                                              \
423         unsigned long __temp = (unsigned long)(x);              \
424         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
425         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
426 })
427 #endif
428 
429 #define __put_user_asm_word(x,__pu_addr,err)                    \
430         __asm__ __volatile__(                                   \
431         "1:     " TUSER(str) "  %1,[%2],#0\n"                   \
432         "2:\n"                                                  \
433         "       .pushsection .fixup,\"ax\"\n"                   \
434         "       .align  2\n"                                    \
435         "3:     mov     %0, %3\n"                               \
436         "       b       2b\n"                                   \
437         "       .popsection\n"                                  \
438         "       .pushsection __ex_table,\"a\"\n"                \
439         "       .align  3\n"                                    \
440         "       .long   1b, 3b\n"                               \
441         "       .popsection"                                    \
442         : "+r" (err)                                            \
443         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
444         : "cc")
445 
446 #ifndef __ARMEB__
447 #define __reg_oper0     "%R2"
448 #define __reg_oper1     "%Q2"
449 #else
450 #define __reg_oper0     "%Q2"
451 #define __reg_oper1     "%R2"
452 #endif
453 
454 #define __put_user_asm_dword(x,__pu_addr,err)                   \
455         __asm__ __volatile__(                                   \
456  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
457  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
458  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
459  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
460         "3:\n"                                                  \
461         "       .pushsection .fixup,\"ax\"\n"                   \
462         "       .align  2\n"                                    \
463         "4:     mov     %0, %3\n"                               \
464         "       b       3b\n"                                   \
465         "       .popsection\n"                                  \
466         "       .pushsection __ex_table,\"a\"\n"                \
467         "       .align  3\n"                                    \
468         "       .long   1b, 4b\n"                               \
469         "       .long   2b, 4b\n"                               \
470         "       .popsection"                                    \
471         : "+r" (err), "+r" (__pu_addr)                          \
472         : "r" (x), "i" (-EFAULT)                                \
473         : "cc")
474 
475 
476 #ifdef CONFIG_MMU
477 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
478 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
479 extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
480 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
481 extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
482 #else
483 #define __copy_from_user(to,from,n)     (memcpy(to, (void __force *)from, n), 0)
484 #define __copy_to_user(to,from,n)       (memcpy((void __force *)to, from, n), 0)
485 #define __clear_user(addr,n)            (memset((void __force *)addr, 0, n), 0)
486 #endif
487 
488 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
489 {
490         if (access_ok(VERIFY_READ, from, n))
491                 n = __copy_from_user(to, from, n);
492         else /* security hole - plug it */
493                 memset(to, 0, n);
494         return n;
495 }
496 
497 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
498 {
499         if (access_ok(VERIFY_WRITE, to, n))
500                 n = __copy_to_user(to, from, n);
501         return n;
502 }
503 
504 #define __copy_to_user_inatomic __copy_to_user
505 #define __copy_from_user_inatomic __copy_from_user
506 
507 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
508 {
509         if (access_ok(VERIFY_WRITE, to, n))
510                 n = __clear_user(to, n);
511         return n;
512 }
513 
514 extern long strncpy_from_user(char *dest, const char __user *src, long count);
515 
516 extern __must_check long strlen_user(const char __user *str);
517 extern __must_check long strnlen_user(const char __user *str, long n);
518 
519 #endif /* _ASMARM_UACCESS_H */
520 

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