x86: use generic strncpy_from_user routine
[linux-3.10.git] / arch / x86 / include / asm / uaccess.h
1 #ifndef _ASM_X86_UACCESS_H
2 #define _ASM_X86_UACCESS_H
3 /*
4  * User space memory access functions
5  */
6 #include <linux/errno.h>
7 #include <linux/compiler.h>
8 #include <linux/thread_info.h>
9 #include <linux/string.h>
10 #include <asm/asm.h>
11 #include <asm/page.h>
12
13 #define VERIFY_READ 0
14 #define VERIFY_WRITE 1
15
16 /*
17  * The fs value determines whether argument validity checking should be
18  * performed or not.  If get_fs() == USER_DS, checking is performed, with
19  * get_fs() == KERNEL_DS, checking is bypassed.
20  *
21  * For historical reasons, these macros are grossly misnamed.
22  */
23
24 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
25
26 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
27 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
28
29 #define get_ds()        (KERNEL_DS)
30 #define get_fs()        (current_thread_info()->addr_limit)
31 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
32
33 #define segment_eq(a, b)        ((a).seg == (b).seg)
34
35 #define user_addr_max() (current_thread_info()->addr_limit.seg)
36 #define __addr_ok(addr)                                 \
37         ((unsigned long __force)(addr) <                \
38          (current_thread_info()->addr_limit.seg))
39
40 /*
41  * Test whether a block of memory is a valid user space address.
42  * Returns 0 if the range is valid, nonzero otherwise.
43  *
44  * This is equivalent to the following test:
45  * (u33)addr + (u33)size > (u33)current->addr_limit.seg (u65 for x86_64)
46  *
47  * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry...
48  */
49
50 #define __range_not_ok(addr, size)                                      \
51 ({                                                                      \
52         unsigned long flag, roksum;                                     \
53         __chk_user_ptr(addr);                                           \
54         asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0"             \
55             : "=&r" (flag), "=r" (roksum)                               \
56             : "1" (addr), "g" ((long)(size)),                           \
57               "rm" (current_thread_info()->addr_limit.seg));            \
58         flag;                                                           \
59 })
60
61 /**
62  * access_ok: - Checks if a user space pointer is valid
63  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
64  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
65  *        to write to a block, it is always safe to read from it.
66  * @addr: User space pointer to start of block to check
67  * @size: Size of block to check
68  *
69  * Context: User context only.  This function may sleep.
70  *
71  * Checks if a pointer to a block of memory in user space is valid.
72  *
73  * Returns true (nonzero) if the memory block may be valid, false (zero)
74  * if it is definitely invalid.
75  *
76  * Note that, depending on architecture, this function probably just
77  * checks that the pointer is in the user space range - after calling
78  * this function, memory access functions may still return -EFAULT.
79  */
80 #define access_ok(type, addr, size) (likely(__range_not_ok(addr, size) == 0))
81
82 /*
83  * The exception table consists of pairs of addresses relative to the
84  * exception table enty itself: the first is the address of an
85  * instruction that is allowed to fault, and the second is the address
86  * at which the program should continue.  No registers are modified,
87  * so it is entirely up to the continuation code to figure out what to
88  * do.
89  *
90  * All the routines below use bits of fixup code that are out of line
91  * with the main instruction path.  This means when everything is well,
92  * we don't even have to jump over them.  Further, they do not intrude
93  * on our cache or tlb entries.
94  */
95
96 struct exception_table_entry {
97         int insn, fixup;
98 };
99 /* This is not the generic standard exception_table_entry format */
100 #define ARCH_HAS_SORT_EXTABLE
101 #define ARCH_HAS_SEARCH_EXTABLE
102
103 extern int fixup_exception(struct pt_regs *regs);
104 extern int early_fixup_exception(unsigned long *ip);
105
106 /*
107  * These are the main single-value transfer routines.  They automatically
108  * use the right size if we just have the right pointer type.
109  *
110  * This gets kind of ugly. We want to return _two_ values in "get_user()"
111  * and yet we don't want to do any pointers, because that is too much
112  * of a performance impact. Thus we have a few rather ugly macros here,
113  * and hide all the ugliness from the user.
114  *
115  * The "__xxx" versions of the user access functions are versions that
116  * do not verify the address space, that must have been done previously
117  * with a separate "access_ok()" call (this is used when we do multiple
118  * accesses to the same area of user memory).
119  */
120
121 extern int __get_user_1(void);
122 extern int __get_user_2(void);
123 extern int __get_user_4(void);
124 extern int __get_user_8(void);
125 extern int __get_user_bad(void);
126
127 #define __get_user_x(size, ret, x, ptr)               \
128         asm volatile("call __get_user_" #size         \
129                      : "=a" (ret), "=d" (x)           \
130                      : "0" (ptr))                     \
131
132 /* Careful: we have to cast the result to the type of the pointer
133  * for sign reasons */
134
135 /**
136  * get_user: - Get a simple variable from user space.
137  * @x:   Variable to store result.
138  * @ptr: Source address, in user space.
139  *
140  * Context: User context only.  This function may sleep.
141  *
142  * This macro copies a single simple variable from user space to kernel
143  * space.  It supports simple types like char and int, but not larger
144  * data types like structures or arrays.
145  *
146  * @ptr must have pointer-to-simple-variable type, and the result of
147  * dereferencing @ptr must be assignable to @x without a cast.
148  *
149  * Returns zero on success, or -EFAULT on error.
150  * On error, the variable @x is set to zero.
151  */
152 #ifdef CONFIG_X86_32
153 #define __get_user_8(__ret_gu, __val_gu, ptr)                           \
154                 __get_user_x(X, __ret_gu, __val_gu, ptr)
155 #else
156 #define __get_user_8(__ret_gu, __val_gu, ptr)                           \
157                 __get_user_x(8, __ret_gu, __val_gu, ptr)
158 #endif
159
160 #define get_user(x, ptr)                                                \
161 ({                                                                      \
162         int __ret_gu;                                                   \
163         unsigned long __val_gu;                                         \
164         __chk_user_ptr(ptr);                                            \
165         might_fault();                                                  \
166         switch (sizeof(*(ptr))) {                                       \
167         case 1:                                                         \
168                 __get_user_x(1, __ret_gu, __val_gu, ptr);               \
169                 break;                                                  \
170         case 2:                                                         \
171                 __get_user_x(2, __ret_gu, __val_gu, ptr);               \
172                 break;                                                  \
173         case 4:                                                         \
174                 __get_user_x(4, __ret_gu, __val_gu, ptr);               \
175                 break;                                                  \
176         case 8:                                                         \
177                 __get_user_8(__ret_gu, __val_gu, ptr);                  \
178                 break;                                                  \
179         default:                                                        \
180                 __get_user_x(X, __ret_gu, __val_gu, ptr);               \
181                 break;                                                  \
182         }                                                               \
183         (x) = (__typeof__(*(ptr)))__val_gu;                             \
184         __ret_gu;                                                       \
185 })
186
187 #define __put_user_x(size, x, ptr, __ret_pu)                    \
188         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
189                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
190
191
192
193 #ifdef CONFIG_X86_32
194 #define __put_user_asm_u64(x, addr, err, errret)                        \
195         asm volatile("1:        movl %%eax,0(%2)\n"                     \
196                      "2:        movl %%edx,4(%2)\n"                     \
197                      "3:\n"                                             \
198                      ".section .fixup,\"ax\"\n"                         \
199                      "4:        movl %3,%0\n"                           \
200                      "  jmp 3b\n"                                       \
201                      ".previous\n"                                      \
202                      _ASM_EXTABLE(1b, 4b)                               \
203                      _ASM_EXTABLE(2b, 4b)                               \
204                      : "=r" (err)                                       \
205                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
206
207 #define __put_user_asm_ex_u64(x, addr)                                  \
208         asm volatile("1:        movl %%eax,0(%1)\n"                     \
209                      "2:        movl %%edx,4(%1)\n"                     \
210                      "3:\n"                                             \
211                      _ASM_EXTABLE_EX(1b, 2b)                            \
212                      _ASM_EXTABLE_EX(2b, 3b)                            \
213                      : : "A" (x), "r" (addr))
214
215 #define __put_user_x8(x, ptr, __ret_pu)                         \
216         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
217                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
218 #else
219 #define __put_user_asm_u64(x, ptr, retval, errret) \
220         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
221 #define __put_user_asm_ex_u64(x, addr)  \
222         __put_user_asm_ex(x, addr, "q", "", "er")
223 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
224 #endif
225
226 extern void __put_user_bad(void);
227
228 /*
229  * Strange magic calling convention: pointer in %ecx,
230  * value in %eax(:%edx), return value in %eax. clobbers %rbx
231  */
232 extern void __put_user_1(void);
233 extern void __put_user_2(void);
234 extern void __put_user_4(void);
235 extern void __put_user_8(void);
236
237 #ifdef CONFIG_X86_WP_WORKS_OK
238
239 /**
240  * put_user: - Write a simple value into user space.
241  * @x:   Value to copy to user space.
242  * @ptr: Destination address, in user space.
243  *
244  * Context: User context only.  This function may sleep.
245  *
246  * This macro copies a single simple value from kernel space to user
247  * space.  It supports simple types like char and int, but not larger
248  * data types like structures or arrays.
249  *
250  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
251  * to the result of dereferencing @ptr.
252  *
253  * Returns zero on success, or -EFAULT on error.
254  */
255 #define put_user(x, ptr)                                        \
256 ({                                                              \
257         int __ret_pu;                                           \
258         __typeof__(*(ptr)) __pu_val;                            \
259         __chk_user_ptr(ptr);                                    \
260         might_fault();                                          \
261         __pu_val = x;                                           \
262         switch (sizeof(*(ptr))) {                               \
263         case 1:                                                 \
264                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
265                 break;                                          \
266         case 2:                                                 \
267                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
268                 break;                                          \
269         case 4:                                                 \
270                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
271                 break;                                          \
272         case 8:                                                 \
273                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
274                 break;                                          \
275         default:                                                \
276                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
277                 break;                                          \
278         }                                                       \
279         __ret_pu;                                               \
280 })
281
282 #define __put_user_size(x, ptr, size, retval, errret)                   \
283 do {                                                                    \
284         retval = 0;                                                     \
285         __chk_user_ptr(ptr);                                            \
286         switch (size) {                                                 \
287         case 1:                                                         \
288                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
289                 break;                                                  \
290         case 2:                                                         \
291                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
292                 break;                                                  \
293         case 4:                                                         \
294                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
295                 break;                                                  \
296         case 8:                                                         \
297                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
298                                    errret);                             \
299                 break;                                                  \
300         default:                                                        \
301                 __put_user_bad();                                       \
302         }                                                               \
303 } while (0)
304
305 #define __put_user_size_ex(x, ptr, size)                                \
306 do {                                                                    \
307         __chk_user_ptr(ptr);                                            \
308         switch (size) {                                                 \
309         case 1:                                                         \
310                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
311                 break;                                                  \
312         case 2:                                                         \
313                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
314                 break;                                                  \
315         case 4:                                                         \
316                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
317                 break;                                                  \
318         case 8:                                                         \
319                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
320                 break;                                                  \
321         default:                                                        \
322                 __put_user_bad();                                       \
323         }                                                               \
324 } while (0)
325
326 #else
327
328 #define __put_user_size(x, ptr, size, retval, errret)                   \
329 do {                                                                    \
330         __typeof__(*(ptr))__pus_tmp = x;                                \
331         retval = 0;                                                     \
332                                                                         \
333         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))    \
334                 retval = errret;                                        \
335 } while (0)
336
337 #define put_user(x, ptr)                                        \
338 ({                                                              \
339         int __ret_pu;                                           \
340         __typeof__(*(ptr))__pus_tmp = x;                        \
341         __ret_pu = 0;                                           \
342         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp,         \
343                                        sizeof(*(ptr))) != 0))   \
344                 __ret_pu = -EFAULT;                             \
345         __ret_pu;                                               \
346 })
347 #endif
348
349 #ifdef CONFIG_X86_32
350 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
351 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
352 #else
353 #define __get_user_asm_u64(x, ptr, retval, errret) \
354          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
355 #define __get_user_asm_ex_u64(x, ptr) \
356          __get_user_asm_ex(x, ptr, "q", "", "=r")
357 #endif
358
359 #define __get_user_size(x, ptr, size, retval, errret)                   \
360 do {                                                                    \
361         retval = 0;                                                     \
362         __chk_user_ptr(ptr);                                            \
363         switch (size) {                                                 \
364         case 1:                                                         \
365                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
366                 break;                                                  \
367         case 2:                                                         \
368                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
369                 break;                                                  \
370         case 4:                                                         \
371                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
372                 break;                                                  \
373         case 8:                                                         \
374                 __get_user_asm_u64(x, ptr, retval, errret);             \
375                 break;                                                  \
376         default:                                                        \
377                 (x) = __get_user_bad();                                 \
378         }                                                               \
379 } while (0)
380
381 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
382         asm volatile("1:        mov"itype" %2,%"rtype"1\n"              \
383                      "2:\n"                                             \
384                      ".section .fixup,\"ax\"\n"                         \
385                      "3:        mov %3,%0\n"                            \
386                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
387                      "  jmp 2b\n"                                       \
388                      ".previous\n"                                      \
389                      _ASM_EXTABLE(1b, 3b)                               \
390                      : "=r" (err), ltype(x)                             \
391                      : "m" (__m(addr)), "i" (errret), "0" (err))
392
393 #define __get_user_size_ex(x, ptr, size)                                \
394 do {                                                                    \
395         __chk_user_ptr(ptr);                                            \
396         switch (size) {                                                 \
397         case 1:                                                         \
398                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
399                 break;                                                  \
400         case 2:                                                         \
401                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
402                 break;                                                  \
403         case 4:                                                         \
404                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
405                 break;                                                  \
406         case 8:                                                         \
407                 __get_user_asm_ex_u64(x, ptr);                          \
408                 break;                                                  \
409         default:                                                        \
410                 (x) = __get_user_bad();                                 \
411         }                                                               \
412 } while (0)
413
414 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
415         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
416                      "2:\n"                                             \
417                      _ASM_EXTABLE_EX(1b, 2b)                            \
418                      : ltype(x) : "m" (__m(addr)))
419
420 #define __put_user_nocheck(x, ptr, size)                        \
421 ({                                                              \
422         int __pu_err;                                           \
423         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
424         __pu_err;                                               \
425 })
426
427 #define __get_user_nocheck(x, ptr, size)                                \
428 ({                                                                      \
429         int __gu_err;                                                   \
430         unsigned long __gu_val;                                         \
431         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
432         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
433         __gu_err;                                                       \
434 })
435
436 /* FIXME: this hack is definitely wrong -AK */
437 struct __large_struct { unsigned long buf[100]; };
438 #define __m(x) (*(struct __large_struct __user *)(x))
439
440 /*
441  * Tell gcc we read from memory instead of writing: this is because
442  * we do not write to any memory gcc knows about, so there are no
443  * aliasing issues.
444  */
445 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
446         asm volatile("1:        mov"itype" %"rtype"1,%2\n"              \
447                      "2:\n"                                             \
448                      ".section .fixup,\"ax\"\n"                         \
449                      "3:        mov %3,%0\n"                            \
450                      "  jmp 2b\n"                                       \
451                      ".previous\n"                                      \
452                      _ASM_EXTABLE(1b, 3b)                               \
453                      : "=r"(err)                                        \
454                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
455
456 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
457         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
458                      "2:\n"                                             \
459                      _ASM_EXTABLE_EX(1b, 2b)                            \
460                      : : ltype(x), "m" (__m(addr)))
461
462 /*
463  * uaccess_try and catch
464  */
465 #define uaccess_try     do {                                            \
466         int prev_err = current_thread_info()->uaccess_err;              \
467         current_thread_info()->uaccess_err = 0;                         \
468         barrier();
469
470 #define uaccess_catch(err)                                              \
471         (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
472         current_thread_info()->uaccess_err = prev_err;                  \
473 } while (0)
474
475 /**
476  * __get_user: - Get a simple variable from user space, with less checking.
477  * @x:   Variable to store result.
478  * @ptr: Source address, in user space.
479  *
480  * Context: User context only.  This function may sleep.
481  *
482  * This macro copies a single simple variable from user space to kernel
483  * space.  It supports simple types like char and int, but not larger
484  * data types like structures or arrays.
485  *
486  * @ptr must have pointer-to-simple-variable type, and the result of
487  * dereferencing @ptr must be assignable to @x without a cast.
488  *
489  * Caller must check the pointer with access_ok() before calling this
490  * function.
491  *
492  * Returns zero on success, or -EFAULT on error.
493  * On error, the variable @x is set to zero.
494  */
495
496 #define __get_user(x, ptr)                                              \
497         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
498
499 /**
500  * __put_user: - Write a simple value into user space, with less checking.
501  * @x:   Value to copy to user space.
502  * @ptr: Destination address, in user space.
503  *
504  * Context: User context only.  This function may sleep.
505  *
506  * This macro copies a single simple value from kernel space to user
507  * space.  It supports simple types like char and int, but not larger
508  * data types like structures or arrays.
509  *
510  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
511  * to the result of dereferencing @ptr.
512  *
513  * Caller must check the pointer with access_ok() before calling this
514  * function.
515  *
516  * Returns zero on success, or -EFAULT on error.
517  */
518
519 #define __put_user(x, ptr)                                              \
520         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
521
522 #define __get_user_unaligned __get_user
523 #define __put_user_unaligned __put_user
524
525 /*
526  * {get|put}_user_try and catch
527  *
528  * get_user_try {
529  *      get_user_ex(...);
530  * } get_user_catch(err)
531  */
532 #define get_user_try            uaccess_try
533 #define get_user_catch(err)     uaccess_catch(err)
534
535 #define get_user_ex(x, ptr)     do {                                    \
536         unsigned long __gue_val;                                        \
537         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
538         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
539 } while (0)
540
541 #ifdef CONFIG_X86_WP_WORKS_OK
542
543 #define put_user_try            uaccess_try
544 #define put_user_catch(err)     uaccess_catch(err)
545
546 #define put_user_ex(x, ptr)                                             \
547         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
548
549 #else /* !CONFIG_X86_WP_WORKS_OK */
550
551 #define put_user_try            do {            \
552         int __uaccess_err = 0;
553
554 #define put_user_catch(err)                     \
555         (err) |= __uaccess_err;                 \
556 } while (0)
557
558 #define put_user_ex(x, ptr)     do {            \
559         __uaccess_err |= __put_user(x, ptr);    \
560 } while (0)
561
562 #endif /* CONFIG_X86_WP_WORKS_OK */
563
564 extern unsigned long
565 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
566 extern __must_check long
567 strncpy_from_user(char *dst, const char __user *src, long count);
568
569 /*
570  * movsl can be slow when source and dest are not both 8-byte aligned
571  */
572 #ifdef CONFIG_X86_INTEL_USERCOPY
573 extern struct movsl_mask {
574         int mask;
575 } ____cacheline_aligned_in_smp movsl_mask;
576 #endif
577
578 #define ARCH_HAS_NOCACHE_UACCESS 1
579
580 #ifdef CONFIG_X86_32
581 # include "uaccess_32.h"
582 #else
583 # include "uaccess_64.h"
584 #endif
585
586 #endif /* _ASM_X86_UACCESS_H */
587