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[mirror_ubuntu-artful-kernel.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 #include <asm/smap.h>
13
14 #define VERIFY_READ 0
15 #define VERIFY_WRITE 1
16
17 /*
18 * The fs value determines whether argument validity checking should be
19 * performed or not. If get_fs() == USER_DS, checking is performed, with
20 * get_fs() == KERNEL_DS, checking is bypassed.
21 *
22 * For historical reasons, these macros are grossly misnamed.
23 */
24
25 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
26
27 #define KERNEL_DS MAKE_MM_SEG(-1UL)
28 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX)
29
30 #define get_ds() (KERNEL_DS)
31 #define get_fs() (current_thread_info()->addr_limit)
32 #define set_fs(x) (current_thread_info()->addr_limit = (x))
33
34 #define segment_eq(a, b) ((a).seg == (b).seg)
35
36 #define user_addr_max() (current_thread_info()->addr_limit.seg)
37 #define __addr_ok(addr) \
38 ((unsigned long __force)(addr) < user_addr_max())
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 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
45 {
46 /*
47 * If we have used "sizeof()" for the size,
48 * we know it won't overflow the limit (but
49 * it might overflow the 'addr', so it's
50 * important to subtract the size from the
51 * limit, not add it to the address).
52 */
53 if (__builtin_constant_p(size))
54 return unlikely(addr > limit - size);
55
56 /* Arbitrary sizes? Be careful about overflow */
57 addr += size;
58 if (unlikely(addr < size))
59 return true;
60 return unlikely(addr > limit);
61 }
62
63 #define __range_not_ok(addr, size, limit) \
64 ({ \
65 __chk_user_ptr(addr); \
66 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
67 })
68
69 /**
70 * access_ok: - Checks if a user space pointer is valid
71 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
72 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
73 * to write to a block, it is always safe to read from it.
74 * @addr: User space pointer to start of block to check
75 * @size: Size of block to check
76 *
77 * Context: User context only. This function may sleep if pagefaults are
78 * enabled.
79 *
80 * Checks if a pointer to a block of memory in user space is valid.
81 *
82 * Returns true (nonzero) if the memory block may be valid, false (zero)
83 * if it is definitely invalid.
84 *
85 * Note that, depending on architecture, this function probably just
86 * checks that the pointer is in the user space range - after calling
87 * this function, memory access functions may still return -EFAULT.
88 */
89 #define access_ok(type, addr, size) \
90 likely(!__range_not_ok(addr, size, user_addr_max()))
91
92 /*
93 * The exception table consists of triples of addresses relative to the
94 * exception table entry itself. The first address is of an instruction
95 * that is allowed to fault, the second is the target at which the program
96 * should continue. The third is a handler function to deal with the fault
97 * caused by the instruction in the first field.
98 *
99 * All the routines below use bits of fixup code that are out of line
100 * with the main instruction path. This means when everything is well,
101 * we don't even have to jump over them. Further, they do not intrude
102 * on our cache or tlb entries.
103 */
104
105 struct exception_table_entry {
106 int insn, fixup, handler;
107 };
108
109 #define ARCH_HAS_RELATIVE_EXTABLE
110
111 extern int fixup_exception(struct pt_regs *regs, int trapnr);
112 extern bool ex_has_fault_handler(unsigned long ip);
113 extern void early_fixup_exception(struct pt_regs *regs, int trapnr);
114
115 /*
116 * These are the main single-value transfer routines. They automatically
117 * use the right size if we just have the right pointer type.
118 *
119 * This gets kind of ugly. We want to return _two_ values in "get_user()"
120 * and yet we don't want to do any pointers, because that is too much
121 * of a performance impact. Thus we have a few rather ugly macros here,
122 * and hide all the ugliness from the user.
123 *
124 * The "__xxx" versions of the user access functions are versions that
125 * do not verify the address space, that must have been done previously
126 * with a separate "access_ok()" call (this is used when we do multiple
127 * accesses to the same area of user memory).
128 */
129
130 extern int __get_user_1(void);
131 extern int __get_user_2(void);
132 extern int __get_user_4(void);
133 extern int __get_user_8(void);
134 extern int __get_user_bad(void);
135
136 #define __uaccess_begin() stac()
137 #define __uaccess_end() clac()
138
139 /*
140 * This is a type: either unsigned long, if the argument fits into
141 * that type, or otherwise unsigned long long.
142 */
143 #define __inttype(x) \
144 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
145
146 /**
147 * get_user: - Get a simple variable from user space.
148 * @x: Variable to store result.
149 * @ptr: Source address, in user space.
150 *
151 * Context: User context only. This function may sleep if pagefaults are
152 * enabled.
153 *
154 * This macro copies a single simple variable from user space to kernel
155 * space. It supports simple types like char and int, but not larger
156 * data types like structures or arrays.
157 *
158 * @ptr must have pointer-to-simple-variable type, and the result of
159 * dereferencing @ptr must be assignable to @x without a cast.
160 *
161 * Returns zero on success, or -EFAULT on error.
162 * On error, the variable @x is set to zero.
163 */
164 /*
165 * Careful: we have to cast the result to the type of the pointer
166 * for sign reasons.
167 *
168 * The use of _ASM_DX as the register specifier is a bit of a
169 * simplification, as gcc only cares about it as the starting point
170 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
171 * (%ecx being the next register in gcc's x86 register sequence), and
172 * %rdx on 64 bits.
173 *
174 * Clang/LLVM cares about the size of the register, but still wants
175 * the base register for something that ends up being a pair.
176 */
177 #define get_user(x, ptr) \
178 ({ \
179 int __ret_gu; \
180 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
181 register void *__sp asm(_ASM_SP); \
182 __chk_user_ptr(ptr); \
183 might_fault(); \
184 asm volatile("call __get_user_%P4" \
185 : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp) \
186 : "0" (ptr), "i" (sizeof(*(ptr)))); \
187 (x) = (__force __typeof__(*(ptr))) __val_gu; \
188 __builtin_expect(__ret_gu, 0); \
189 })
190
191 #define __put_user_x(size, x, ptr, __ret_pu) \
192 asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
193 : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
194
195
196
197 #ifdef CONFIG_X86_32
198 #define __put_user_asm_u64(x, addr, err, errret) \
199 asm volatile("\n" \
200 "1: movl %%eax,0(%2)\n" \
201 "2: movl %%edx,4(%2)\n" \
202 "3:" \
203 ".section .fixup,\"ax\"\n" \
204 "4: movl %3,%0\n" \
205 " jmp 3b\n" \
206 ".previous\n" \
207 _ASM_EXTABLE(1b, 4b) \
208 _ASM_EXTABLE(2b, 4b) \
209 : "=r" (err) \
210 : "A" (x), "r" (addr), "i" (errret), "0" (err))
211
212 #define __put_user_asm_ex_u64(x, addr) \
213 asm volatile("\n" \
214 "1: movl %%eax,0(%1)\n" \
215 "2: movl %%edx,4(%1)\n" \
216 "3:" \
217 _ASM_EXTABLE_EX(1b, 2b) \
218 _ASM_EXTABLE_EX(2b, 3b) \
219 : : "A" (x), "r" (addr))
220
221 #define __put_user_x8(x, ptr, __ret_pu) \
222 asm volatile("call __put_user_8" : "=a" (__ret_pu) \
223 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
224 #else
225 #define __put_user_asm_u64(x, ptr, retval, errret) \
226 __put_user_asm(x, ptr, retval, "q", "", "er", errret)
227 #define __put_user_asm_ex_u64(x, addr) \
228 __put_user_asm_ex(x, addr, "q", "", "er")
229 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
230 #endif
231
232 extern void __put_user_bad(void);
233
234 /*
235 * Strange magic calling convention: pointer in %ecx,
236 * value in %eax(:%edx), return value in %eax. clobbers %rbx
237 */
238 extern void __put_user_1(void);
239 extern void __put_user_2(void);
240 extern void __put_user_4(void);
241 extern void __put_user_8(void);
242
243 /**
244 * put_user: - Write a simple value into user space.
245 * @x: Value to copy to user space.
246 * @ptr: Destination address, in user space.
247 *
248 * Context: User context only. This function may sleep if pagefaults are
249 * enabled.
250 *
251 * This macro copies a single simple value from kernel space to user
252 * space. It supports simple types like char and int, but not larger
253 * data types like structures or arrays.
254 *
255 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
256 * to the result of dereferencing @ptr.
257 *
258 * Returns zero on success, or -EFAULT on error.
259 */
260 #define put_user(x, ptr) \
261 ({ \
262 int __ret_pu; \
263 __typeof__(*(ptr)) __pu_val; \
264 __chk_user_ptr(ptr); \
265 might_fault(); \
266 __pu_val = x; \
267 switch (sizeof(*(ptr))) { \
268 case 1: \
269 __put_user_x(1, __pu_val, ptr, __ret_pu); \
270 break; \
271 case 2: \
272 __put_user_x(2, __pu_val, ptr, __ret_pu); \
273 break; \
274 case 4: \
275 __put_user_x(4, __pu_val, ptr, __ret_pu); \
276 break; \
277 case 8: \
278 __put_user_x8(__pu_val, ptr, __ret_pu); \
279 break; \
280 default: \
281 __put_user_x(X, __pu_val, ptr, __ret_pu); \
282 break; \
283 } \
284 __builtin_expect(__ret_pu, 0); \
285 })
286
287 #define __put_user_size(x, ptr, size, retval, errret) \
288 do { \
289 retval = 0; \
290 __chk_user_ptr(ptr); \
291 switch (size) { \
292 case 1: \
293 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
294 break; \
295 case 2: \
296 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
297 break; \
298 case 4: \
299 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
300 break; \
301 case 8: \
302 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \
303 errret); \
304 break; \
305 default: \
306 __put_user_bad(); \
307 } \
308 } while (0)
309
310 /*
311 * This doesn't do __uaccess_begin/end - the exception handling
312 * around it must do that.
313 */
314 #define __put_user_size_ex(x, ptr, size) \
315 do { \
316 __chk_user_ptr(ptr); \
317 switch (size) { \
318 case 1: \
319 __put_user_asm_ex(x, ptr, "b", "b", "iq"); \
320 break; \
321 case 2: \
322 __put_user_asm_ex(x, ptr, "w", "w", "ir"); \
323 break; \
324 case 4: \
325 __put_user_asm_ex(x, ptr, "l", "k", "ir"); \
326 break; \
327 case 8: \
328 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr); \
329 break; \
330 default: \
331 __put_user_bad(); \
332 } \
333 } while (0)
334
335 #ifdef CONFIG_X86_32
336 #define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad()
337 #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad()
338 #else
339 #define __get_user_asm_u64(x, ptr, retval, errret) \
340 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
341 #define __get_user_asm_ex_u64(x, ptr) \
342 __get_user_asm_ex(x, ptr, "q", "", "=r")
343 #endif
344
345 #define __get_user_size(x, ptr, size, retval, errret) \
346 do { \
347 retval = 0; \
348 __chk_user_ptr(ptr); \
349 switch (size) { \
350 case 1: \
351 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
352 break; \
353 case 2: \
354 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
355 break; \
356 case 4: \
357 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
358 break; \
359 case 8: \
360 __get_user_asm_u64(x, ptr, retval, errret); \
361 break; \
362 default: \
363 (x) = __get_user_bad(); \
364 } \
365 } while (0)
366
367 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
368 asm volatile("\n" \
369 "1: mov"itype" %2,%"rtype"1\n" \
370 "2:\n" \
371 ".section .fixup,\"ax\"\n" \
372 "3: mov %3,%0\n" \
373 " xor"itype" %"rtype"1,%"rtype"1\n" \
374 " jmp 2b\n" \
375 ".previous\n" \
376 _ASM_EXTABLE(1b, 3b) \
377 : "=r" (err), ltype(x) \
378 : "m" (__m(addr)), "i" (errret), "0" (err))
379
380 /*
381 * This doesn't do __uaccess_begin/end - the exception handling
382 * around it must do that.
383 */
384 #define __get_user_size_ex(x, ptr, size) \
385 do { \
386 __chk_user_ptr(ptr); \
387 switch (size) { \
388 case 1: \
389 __get_user_asm_ex(x, ptr, "b", "b", "=q"); \
390 break; \
391 case 2: \
392 __get_user_asm_ex(x, ptr, "w", "w", "=r"); \
393 break; \
394 case 4: \
395 __get_user_asm_ex(x, ptr, "l", "k", "=r"); \
396 break; \
397 case 8: \
398 __get_user_asm_ex_u64(x, ptr); \
399 break; \
400 default: \
401 (x) = __get_user_bad(); \
402 } \
403 } while (0)
404
405 #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \
406 asm volatile("1: mov"itype" %1,%"rtype"0\n" \
407 "2:\n" \
408 _ASM_EXTABLE_EX(1b, 2b) \
409 : ltype(x) : "m" (__m(addr)))
410
411 #define __put_user_nocheck(x, ptr, size) \
412 ({ \
413 int __pu_err; \
414 __uaccess_begin(); \
415 __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
416 __uaccess_end(); \
417 __builtin_expect(__pu_err, 0); \
418 })
419
420 #define __get_user_nocheck(x, ptr, size) \
421 ({ \
422 int __gu_err; \
423 unsigned long __gu_val; \
424 __uaccess_begin(); \
425 __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
426 __uaccess_end(); \
427 (x) = (__force __typeof__(*(ptr)))__gu_val; \
428 __builtin_expect(__gu_err, 0); \
429 })
430
431 /* FIXME: this hack is definitely wrong -AK */
432 struct __large_struct { unsigned long buf[100]; };
433 #define __m(x) (*(struct __large_struct __user *)(x))
434
435 /*
436 * Tell gcc we read from memory instead of writing: this is because
437 * we do not write to any memory gcc knows about, so there are no
438 * aliasing issues.
439 */
440 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
441 asm volatile("\n" \
442 "1: mov"itype" %"rtype"1,%2\n" \
443 "2:\n" \
444 ".section .fixup,\"ax\"\n" \
445 "3: mov %3,%0\n" \
446 " jmp 2b\n" \
447 ".previous\n" \
448 _ASM_EXTABLE(1b, 3b) \
449 : "=r"(err) \
450 : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
451
452 #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \
453 asm volatile("1: mov"itype" %"rtype"0,%1\n" \
454 "2:\n" \
455 _ASM_EXTABLE_EX(1b, 2b) \
456 : : ltype(x), "m" (__m(addr)))
457
458 /*
459 * uaccess_try and catch
460 */
461 #define uaccess_try do { \
462 current_thread_info()->uaccess_err = 0; \
463 __uaccess_begin(); \
464 barrier();
465
466 #define uaccess_catch(err) \
467 __uaccess_end(); \
468 (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \
469 } while (0)
470
471 /**
472 * __get_user: - Get a simple variable from user space, with less checking.
473 * @x: Variable to store result.
474 * @ptr: Source address, in user space.
475 *
476 * Context: User context only. This function may sleep if pagefaults are
477 * enabled.
478 *
479 * This macro copies a single simple variable from user space to kernel
480 * space. It supports simple types like char and int, but not larger
481 * data types like structures or arrays.
482 *
483 * @ptr must have pointer-to-simple-variable type, and the result of
484 * dereferencing @ptr must be assignable to @x without a cast.
485 *
486 * Caller must check the pointer with access_ok() before calling this
487 * function.
488 *
489 * Returns zero on success, or -EFAULT on error.
490 * On error, the variable @x is set to zero.
491 */
492
493 #define __get_user(x, ptr) \
494 __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
495
496 /**
497 * __put_user: - Write a simple value into user space, with less checking.
498 * @x: Value to copy to user space.
499 * @ptr: Destination address, in user space.
500 *
501 * Context: User context only. This function may sleep if pagefaults are
502 * enabled.
503 *
504 * This macro copies a single simple value from kernel space to user
505 * space. It supports simple types like char and int, but not larger
506 * data types like structures or arrays.
507 *
508 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
509 * to the result of dereferencing @ptr.
510 *
511 * Caller must check the pointer with access_ok() before calling this
512 * function.
513 *
514 * Returns zero on success, or -EFAULT on error.
515 */
516
517 #define __put_user(x, ptr) \
518 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
519
520 #define __get_user_unaligned __get_user
521 #define __put_user_unaligned __put_user
522
523 /*
524 * {get|put}_user_try and catch
525 *
526 * get_user_try {
527 * get_user_ex(...);
528 * } get_user_catch(err)
529 */
530 #define get_user_try uaccess_try
531 #define get_user_catch(err) uaccess_catch(err)
532
533 #define get_user_ex(x, ptr) do { \
534 unsigned long __gue_val; \
535 __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr)))); \
536 (x) = (__force __typeof__(*(ptr)))__gue_val; \
537 } while (0)
538
539 #define put_user_try uaccess_try
540 #define put_user_catch(err) uaccess_catch(err)
541
542 #define put_user_ex(x, ptr) \
543 __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
544
545 extern unsigned long
546 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
547 extern __must_check long
548 strncpy_from_user(char *dst, const char __user *src, long count);
549
550 extern __must_check long strlen_user(const char __user *str);
551 extern __must_check long strnlen_user(const char __user *str, long n);
552
553 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
554 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
555
556 extern void __cmpxchg_wrong_size(void)
557 __compiletime_error("Bad argument size for cmpxchg");
558
559 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \
560 ({ \
561 int __ret = 0; \
562 __typeof__(ptr) __uval = (uval); \
563 __typeof__(*(ptr)) __old = (old); \
564 __typeof__(*(ptr)) __new = (new); \
565 __uaccess_begin(); \
566 switch (size) { \
567 case 1: \
568 { \
569 asm volatile("\n" \
570 "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \
571 "2:\n" \
572 "\t.section .fixup, \"ax\"\n" \
573 "3:\tmov %3, %0\n" \
574 "\tjmp 2b\n" \
575 "\t.previous\n" \
576 _ASM_EXTABLE(1b, 3b) \
577 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
578 : "i" (-EFAULT), "q" (__new), "1" (__old) \
579 : "memory" \
580 ); \
581 break; \
582 } \
583 case 2: \
584 { \
585 asm volatile("\n" \
586 "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \
587 "2:\n" \
588 "\t.section .fixup, \"ax\"\n" \
589 "3:\tmov %3, %0\n" \
590 "\tjmp 2b\n" \
591 "\t.previous\n" \
592 _ASM_EXTABLE(1b, 3b) \
593 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
594 : "i" (-EFAULT), "r" (__new), "1" (__old) \
595 : "memory" \
596 ); \
597 break; \
598 } \
599 case 4: \
600 { \
601 asm volatile("\n" \
602 "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \
603 "2:\n" \
604 "\t.section .fixup, \"ax\"\n" \
605 "3:\tmov %3, %0\n" \
606 "\tjmp 2b\n" \
607 "\t.previous\n" \
608 _ASM_EXTABLE(1b, 3b) \
609 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
610 : "i" (-EFAULT), "r" (__new), "1" (__old) \
611 : "memory" \
612 ); \
613 break; \
614 } \
615 case 8: \
616 { \
617 if (!IS_ENABLED(CONFIG_X86_64)) \
618 __cmpxchg_wrong_size(); \
619 \
620 asm volatile("\n" \
621 "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \
622 "2:\n" \
623 "\t.section .fixup, \"ax\"\n" \
624 "3:\tmov %3, %0\n" \
625 "\tjmp 2b\n" \
626 "\t.previous\n" \
627 _ASM_EXTABLE(1b, 3b) \
628 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \
629 : "i" (-EFAULT), "r" (__new), "1" (__old) \
630 : "memory" \
631 ); \
632 break; \
633 } \
634 default: \
635 __cmpxchg_wrong_size(); \
636 } \
637 __uaccess_end(); \
638 *__uval = __old; \
639 __ret; \
640 })
641
642 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \
643 ({ \
644 access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \
645 __user_atomic_cmpxchg_inatomic((uval), (ptr), \
646 (old), (new), sizeof(*(ptr))) : \
647 -EFAULT; \
648 })
649
650 /*
651 * movsl can be slow when source and dest are not both 8-byte aligned
652 */
653 #ifdef CONFIG_X86_INTEL_USERCOPY
654 extern struct movsl_mask {
655 int mask;
656 } ____cacheline_aligned_in_smp movsl_mask;
657 #endif
658
659 #define ARCH_HAS_NOCACHE_UACCESS 1
660
661 #ifdef CONFIG_X86_32
662 # include <asm/uaccess_32.h>
663 #else
664 # include <asm/uaccess_64.h>
665 #endif
666
667 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
668 unsigned n);
669 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
670 unsigned n);
671
672 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
673 # define copy_user_diag __compiletime_error
674 #else
675 # define copy_user_diag __compiletime_warning
676 #endif
677
678 extern void copy_user_diag("copy_from_user() buffer size is too small")
679 copy_from_user_overflow(void);
680 extern void copy_user_diag("copy_to_user() buffer size is too small")
681 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
682
683 #undef copy_user_diag
684
685 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
686
687 extern void
688 __compiletime_warning("copy_from_user() buffer size is not provably correct")
689 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
690 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
691
692 extern void
693 __compiletime_warning("copy_to_user() buffer size is not provably correct")
694 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
695 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
696
697 #else
698
699 static inline void
700 __copy_from_user_overflow(int size, unsigned long count)
701 {
702 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
703 }
704
705 #define __copy_to_user_overflow __copy_from_user_overflow
706
707 #endif
708
709 static inline unsigned long __must_check
710 copy_from_user(void *to, const void __user *from, unsigned long n)
711 {
712 int sz = __compiletime_object_size(to);
713
714 might_fault();
715
716 /*
717 * While we would like to have the compiler do the checking for us
718 * even in the non-constant size case, any false positives there are
719 * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
720 * without - the [hopefully] dangerous looking nature of the warning
721 * would make people go look at the respecitive call sites over and
722 * over again just to find that there's no problem).
723 *
724 * And there are cases where it's just not realistic for the compiler
725 * to prove the count to be in range. For example when multiple call
726 * sites of a helper function - perhaps in different source files -
727 * all doing proper range checking, yet the helper function not doing
728 * so again.
729 *
730 * Therefore limit the compile time checking to the constant size
731 * case, and do only runtime checking for non-constant sizes.
732 */
733
734 if (likely(sz < 0 || sz >= n))
735 n = _copy_from_user(to, from, n);
736 else if(__builtin_constant_p(n))
737 copy_from_user_overflow();
738 else
739 __copy_from_user_overflow(sz, n);
740
741 return n;
742 }
743
744 static inline unsigned long __must_check
745 copy_to_user(void __user *to, const void *from, unsigned long n)
746 {
747 int sz = __compiletime_object_size(from);
748
749 might_fault();
750
751 /* See the comment in copy_from_user() above. */
752 if (likely(sz < 0 || sz >= n))
753 n = _copy_to_user(to, from, n);
754 else if(__builtin_constant_p(n))
755 copy_to_user_overflow();
756 else
757 __copy_to_user_overflow(sz, n);
758
759 return n;
760 }
761
762 #undef __copy_from_user_overflow
763 #undef __copy_to_user_overflow
764
765 /*
766 * We rely on the nested NMI work to allow atomic faults from the NMI path; the
767 * nested NMI paths are careful to preserve CR2.
768 *
769 * Caller must use pagefault_enable/disable, or run in interrupt context,
770 * and also do a uaccess_ok() check
771 */
772 #define __copy_from_user_nmi __copy_from_user_inatomic
773
774 /*
775 * The "unsafe" user accesses aren't really "unsafe", but the naming
776 * is a big fat warning: you have to not only do the access_ok()
777 * checking before using them, but you have to surround them with the
778 * user_access_begin/end() pair.
779 */
780 #define user_access_begin() __uaccess_begin()
781 #define user_access_end() __uaccess_end()
782
783 #define unsafe_put_user(x, ptr) \
784 ({ \
785 int __pu_err; \
786 __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT); \
787 __builtin_expect(__pu_err, 0); \
788 })
789
790 #define unsafe_get_user(x, ptr) \
791 ({ \
792 int __gu_err; \
793 unsigned long __gu_val; \
794 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT); \
795 (x) = (__force __typeof__(*(ptr)))__gu_val; \
796 __builtin_expect(__gu_err, 0); \
797 })
798
799 #endif /* _ASM_X86_UACCESS_H */
800
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