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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 #if __LINUX_ARM_ARCH__ < 6
 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 
111 #define __GUP_CLOBBER_1 "lr", "cc"
112 #ifdef CONFIG_CPU_USE_DOMAINS
113 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
114 #else
115 #define __GUP_CLOBBER_2 "lr", "cc"
116 #endif
117 #define __GUP_CLOBBER_4 "lr", "cc"
118 
119 #define __get_user_x(__r2,__p,__e,__l,__s)                              \
120            __asm__ __volatile__ (                                       \
121                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
122                 __asmeq("%3", "r1")                                     \
123                 "bl     __get_user_" #__s                               \
124                 : "=&r" (__e), "=r" (__r2)                              \
125                 : "" (__p), "r" (__l)                                  \
126                 : __GUP_CLOBBER_##__s)
127 
128 #define __get_user_check(x,p)                                                   \
129         ({                                                              \
130                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
131                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
132                 register unsigned long __r2 asm("r2");                  \
133                 register unsigned long __l asm("r1") = __limit;         \
134                 register int __e asm("r0");                             \
135                 switch (sizeof(*(__p))) {                               \
136                 case 1:                                                 \
137                         __get_user_x(__r2, __p, __e, __l, 1);           \
138                         break;                                          \
139                 case 2:                                                 \
140                         __get_user_x(__r2, __p, __e, __l, 2);           \
141                         break;                                          \
142                 case 4:                                                 \
143                         __get_user_x(__r2, __p, __e, __l, 4);           \
144                         break;                                          \
145                 default: __e = __get_user_bad(); break;                 \
146                 }                                                       \
147                 x = (typeof(*(p))) __r2;                                \
148                 __e;                                                    \
149         })
150 
151 #define get_user(x,p)                                                   \
152         ({                                                              \
153                 might_fault();                                          \
154                 __get_user_check(x,p);                                  \
155          })
156 
157 extern int __put_user_1(void *, unsigned int);
158 extern int __put_user_2(void *, unsigned int);
159 extern int __put_user_4(void *, unsigned int);
160 extern int __put_user_8(void *, unsigned long long);
161 
162 #define __put_user_x(__r2,__p,__e,__l,__s)                              \
163            __asm__ __volatile__ (                                       \
164                 __asmeq("%0", "r0") __asmeq("%2", "r2")                 \
165                 __asmeq("%3", "r1")                                     \
166                 "bl     __put_user_" #__s                               \
167                 : "=&r" (__e)                                           \
168                 : "" (__p), "r" (__r2), "r" (__l)                      \
169                 : "ip", "lr", "cc")
170 
171 #define __put_user_check(x,p)                                                   \
172         ({                                                              \
173                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
174                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
175                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
176                 register unsigned long __l asm("r1") = __limit;         \
177                 register int __e asm("r0");                             \
178                 switch (sizeof(*(__p))) {                               \
179                 case 1:                                                 \
180                         __put_user_x(__r2, __p, __e, __l, 1);           \
181                         break;                                          \
182                 case 2:                                                 \
183                         __put_user_x(__r2, __p, __e, __l, 2);           \
184                         break;                                          \
185                 case 4:                                                 \
186                         __put_user_x(__r2, __p, __e, __l, 4);           \
187                         break;                                          \
188                 case 8:                                                 \
189                         __put_user_x(__r2, __p, __e, __l, 8);           \
190                         break;                                          \
191                 default: __e = __put_user_bad(); break;                 \
192                 }                                                       \
193                 __e;                                                    \
194         })
195 
196 #define put_user(x,p)                                                   \
197         ({                                                              \
198                 might_fault();                                          \
199                 __put_user_check(x,p);                                  \
200          })
201 
202 #else /* CONFIG_MMU */
203 
204 /*
205  * uClinux has only one addr space, so has simplified address limits.
206  */
207 #define USER_DS                 KERNEL_DS
208 
209 #define segment_eq(a,b)         (1)
210 #define __addr_ok(addr)         ((void)(addr),1)
211 #define __range_ok(addr,size)   ((void)(addr),0)
212 #define get_fs()                (KERNEL_DS)
213 
214 static inline void set_fs(mm_segment_t fs)
215 {
216 }
217 
218 #define get_user(x,p)   __get_user(x,p)
219 #define put_user(x,p)   __put_user(x,p)
220 
221 #endif /* CONFIG_MMU */
222 
223 #define access_ok(type,addr,size)       (__range_ok(addr,size) == 0)
224 
225 #define user_addr_max() \
226         (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
227 
228 /*
229  * The "__xxx" versions of the user access functions do not verify the
230  * address space - it must have been done previously with a separate
231  * "access_ok()" call.
232  *
233  * The "xxx_error" versions set the third argument to EFAULT if an
234  * error occurs, and leave it unchanged on success.  Note that these
235  * versions are void (ie, don't return a value as such).
236  */
237 #define __get_user(x,ptr)                                               \
238 ({                                                                      \
239         long __gu_err = 0;                                              \
240         __get_user_err((x),(ptr),__gu_err);                             \
241         __gu_err;                                                       \
242 })
243 
244 #define __get_user_error(x,ptr,err)                                     \
245 ({                                                                      \
246         __get_user_err((x),(ptr),err);                                  \
247         (void) 0;                                                       \
248 })
249 
250 #define __get_user_err(x,ptr,err)                                       \
251 do {                                                                    \
252         unsigned long __gu_addr = (unsigned long)(ptr);                 \
253         unsigned long __gu_val;                                         \
254         __chk_user_ptr(ptr);                                            \
255         might_fault();                                                  \
256         switch (sizeof(*(ptr))) {                                       \
257         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
258         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
259         case 4: __get_user_asm_word(__gu_val,__gu_addr,err);    break;  \
260         default: (__gu_val) = __get_user_bad();                         \
261         }                                                               \
262         (x) = (__typeof__(*(ptr)))__gu_val;                             \
263 } while (0)
264 
265 #define __get_user_asm_byte(x,addr,err)                         \
266         __asm__ __volatile__(                                   \
267         "1:     " TUSER(ldrb) " %1,[%2],#0\n"                   \
268         "2:\n"                                                  \
269         "       .pushsection .fixup,\"ax\"\n"                   \
270         "       .align  2\n"                                    \
271         "3:     mov     %0, %3\n"                               \
272         "       mov     %1, #0\n"                               \
273         "       b       2b\n"                                   \
274         "       .popsection\n"                                  \
275         "       .pushsection __ex_table,\"a\"\n"                \
276         "       .align  3\n"                                    \
277         "       .long   1b, 3b\n"                               \
278         "       .popsection"                                    \
279         : "+r" (err), "=&r" (x)                                 \
280         : "r" (addr), "i" (-EFAULT)                             \
281         : "cc")
282 
283 #ifndef __ARMEB__
284 #define __get_user_asm_half(x,__gu_addr,err)                    \
285 ({                                                              \
286         unsigned long __b1, __b2;                               \
287         __get_user_asm_byte(__b1, __gu_addr, err);              \
288         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
289         (x) = __b1 | (__b2 << 8);                               \
290 })
291 #else
292 #define __get_user_asm_half(x,__gu_addr,err)                    \
293 ({                                                              \
294         unsigned long __b1, __b2;                               \
295         __get_user_asm_byte(__b1, __gu_addr, err);              \
296         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
297         (x) = (__b1 << 8) | __b2;                               \
298 })
299 #endif
300 
301 #define __get_user_asm_word(x,addr,err)                         \
302         __asm__ __volatile__(                                   \
303         "1:     " TUSER(ldr) "  %1,[%2],#0\n"                   \
304         "2:\n"                                                  \
305         "       .pushsection .fixup,\"ax\"\n"                   \
306         "       .align  2\n"                                    \
307         "3:     mov     %0, %3\n"                               \
308         "       mov     %1, #0\n"                               \
309         "       b       2b\n"                                   \
310         "       .popsection\n"                                  \
311         "       .pushsection __ex_table,\"a\"\n"                \
312         "       .align  3\n"                                    \
313         "       .long   1b, 3b\n"                               \
314         "       .popsection"                                    \
315         : "+r" (err), "=&r" (x)                                 \
316         : "r" (addr), "i" (-EFAULT)                             \
317         : "cc")
318 
319 #define __put_user(x,ptr)                                               \
320 ({                                                                      \
321         long __pu_err = 0;                                              \
322         __put_user_err((x),(ptr),__pu_err);                             \
323         __pu_err;                                                       \
324 })
325 
326 #define __put_user_error(x,ptr,err)                                     \
327 ({                                                                      \
328         __put_user_err((x),(ptr),err);                                  \
329         (void) 0;                                                       \
330 })
331 
332 #define __put_user_err(x,ptr,err)                                       \
333 do {                                                                    \
334         unsigned long __pu_addr = (unsigned long)(ptr);                 \
335         __typeof__(*(ptr)) __pu_val = (x);                              \
336         __chk_user_ptr(ptr);                                            \
337         might_fault();                                                  \
338         switch (sizeof(*(ptr))) {                                       \
339         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
340         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \
341         case 4: __put_user_asm_word(__pu_val,__pu_addr,err);    break;  \
342         case 8: __put_user_asm_dword(__pu_val,__pu_addr,err);   break;  \
343         default: __put_user_bad();                                      \
344         }                                                               \
345 } while (0)
346 
347 #define __put_user_asm_byte(x,__pu_addr,err)                    \
348         __asm__ __volatile__(                                   \
349         "1:     " TUSER(strb) " %1,[%2],#0\n"                   \
350         "2:\n"                                                  \
351         "       .pushsection .fixup,\"ax\"\n"                   \
352         "       .align  2\n"                                    \
353         "3:     mov     %0, %3\n"                               \
354         "       b       2b\n"                                   \
355         "       .popsection\n"                                  \
356         "       .pushsection __ex_table,\"a\"\n"                \
357         "       .align  3\n"                                    \
358         "       .long   1b, 3b\n"                               \
359         "       .popsection"                                    \
360         : "+r" (err)                                            \
361         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
362         : "cc")
363 
364 #ifndef __ARMEB__
365 #define __put_user_asm_half(x,__pu_addr,err)                    \
366 ({                                                              \
367         unsigned long __temp = (unsigned long)(x);              \
368         __put_user_asm_byte(__temp, __pu_addr, err);            \
369         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
370 })
371 #else
372 #define __put_user_asm_half(x,__pu_addr,err)                    \
373 ({                                                              \
374         unsigned long __temp = (unsigned long)(x);              \
375         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
376         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
377 })
378 #endif
379 
380 #define __put_user_asm_word(x,__pu_addr,err)                    \
381         __asm__ __volatile__(                                   \
382         "1:     " TUSER(str) "  %1,[%2],#0\n"                   \
383         "2:\n"                                                  \
384         "       .pushsection .fixup,\"ax\"\n"                   \
385         "       .align  2\n"                                    \
386         "3:     mov     %0, %3\n"                               \
387         "       b       2b\n"                                   \
388         "       .popsection\n"                                  \
389         "       .pushsection __ex_table,\"a\"\n"                \
390         "       .align  3\n"                                    \
391         "       .long   1b, 3b\n"                               \
392         "       .popsection"                                    \
393         : "+r" (err)                                            \
394         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
395         : "cc")
396 
397 #ifndef __ARMEB__
398 #define __reg_oper0     "%R2"
399 #define __reg_oper1     "%Q2"
400 #else
401 #define __reg_oper0     "%Q2"
402 #define __reg_oper1     "%R2"
403 #endif
404 
405 #define __put_user_asm_dword(x,__pu_addr,err)                   \
406         __asm__ __volatile__(                                   \
407  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
408  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
409  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
410  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
411         "3:\n"                                                  \
412         "       .pushsection .fixup,\"ax\"\n"                   \
413         "       .align  2\n"                                    \
414         "4:     mov     %0, %3\n"                               \
415         "       b       3b\n"                                   \
416         "       .popsection\n"                                  \
417         "       .pushsection __ex_table,\"a\"\n"                \
418         "       .align  3\n"                                    \
419         "       .long   1b, 4b\n"                               \
420         "       .long   2b, 4b\n"                               \
421         "       .popsection"                                    \
422         : "+r" (err), "+r" (__pu_addr)                          \
423         : "r" (x), "i" (-EFAULT)                                \
424         : "cc")
425 
426 
427 #ifdef CONFIG_MMU
428 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
429 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
430 extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
431 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
432 extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
433 #else
434 #define __copy_from_user(to,from,n)     (memcpy(to, (void __force *)from, n), 0)
435 #define __copy_to_user(to,from,n)       (memcpy((void __force *)to, from, n), 0)
436 #define __clear_user(addr,n)            (memset((void __force *)addr, 0, n), 0)
437 #endif
438 
439 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
440 {
441         if (access_ok(VERIFY_READ, from, n))
442                 n = __copy_from_user(to, from, n);
443         else /* security hole - plug it */
444                 memset(to, 0, n);
445         return n;
446 }
447 
448 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
449 {
450         if (access_ok(VERIFY_WRITE, to, n))
451                 n = __copy_to_user(to, from, n);
452         return n;
453 }
454 
455 #define __copy_to_user_inatomic __copy_to_user
456 #define __copy_from_user_inatomic __copy_from_user
457 
458 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
459 {
460         if (access_ok(VERIFY_WRITE, to, n))
461                 n = __clear_user(to, n);
462         return n;
463 }
464 
465 extern long strncpy_from_user(char *dest, const char __user *src, long count);
466 
467 extern __must_check long strlen_user(const char __user *str);
468 extern __must_check long strnlen_user(const char __user *str, long n);
469 
470 #endif /* _ASMARM_UACCESS_H */
471 

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