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-rw-r--r--arch/x86/include/asm/uaccess.h454
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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/prefetch.h>
10#include <linux/string.h>
11#include <asm/asm.h>
12#include <asm/page.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(PAGE_OFFSET)
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 __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: the first is the
84 * address of an instruction that is allowed to fault, and the second is
85 * the address at which the program should continue. No registers are
86 * modified, so it is entirely up to the continuation code to figure out
87 * what to do.
88 *
89 * All the routines below use bits of fixup code that are out of line
90 * with the main instruction path. This means when everything is well,
91 * we don't even have to jump over them. Further, they do not intrude
92 * on our cache or tlb entries.
93 */
94
95struct exception_table_entry {
96 unsigned long insn, fixup;
97};
98
99extern int fixup_exception(struct pt_regs *regs);
100
101/*
102 * These are the main single-value transfer routines. They automatically
103 * use the right size if we just have the right pointer type.
104 *
105 * This gets kind of ugly. We want to return _two_ values in "get_user()"
106 * and yet we don't want to do any pointers, because that is too much
107 * of a performance impact. Thus we have a few rather ugly macros here,
108 * and hide all the ugliness from the user.
109 *
110 * The "__xxx" versions of the user access functions are versions that
111 * do not verify the address space, that must have been done previously
112 * with a separate "access_ok()" call (this is used when we do multiple
113 * accesses to the same area of user memory).
114 */
115
116extern int __get_user_1(void);
117extern int __get_user_2(void);
118extern int __get_user_4(void);
119extern int __get_user_8(void);
120extern int __get_user_bad(void);
121
122#define __get_user_x(size, ret, x, ptr) \
123 asm volatile("call __get_user_" #size \
124 : "=a" (ret),"=d" (x) \
125 : "0" (ptr)) \
126
127/* Careful: we have to cast the result to the type of the pointer
128 * for sign reasons */
129
130/**
131 * get_user: - Get a simple variable from user space.
132 * @x: Variable to store result.
133 * @ptr: Source address, in user space.
134 *
135 * Context: User context only. This function may sleep.
136 *
137 * This macro copies a single simple variable from user space to kernel
138 * space. It supports simple types like char and int, but not larger
139 * data types like structures or arrays.
140 *
141 * @ptr must have pointer-to-simple-variable type, and the result of
142 * dereferencing @ptr must be assignable to @x without a cast.
143 *
144 * Returns zero on success, or -EFAULT on error.
145 * On error, the variable @x is set to zero.
146 */
147#ifdef CONFIG_X86_32
148#define __get_user_8(__ret_gu, __val_gu, ptr) \
149 __get_user_x(X, __ret_gu, __val_gu, ptr)
150#else
151#define __get_user_8(__ret_gu, __val_gu, ptr) \
152 __get_user_x(8, __ret_gu, __val_gu, ptr)
153#endif
154
155#define get_user(x, ptr) \
156({ \
157 int __ret_gu; \
158 unsigned long __val_gu; \
159 __chk_user_ptr(ptr); \
160 switch (sizeof(*(ptr))) { \
161 case 1: \
162 __get_user_x(1, __ret_gu, __val_gu, ptr); \
163 break; \
164 case 2: \
165 __get_user_x(2, __ret_gu, __val_gu, ptr); \
166 break; \
167 case 4: \
168 __get_user_x(4, __ret_gu, __val_gu, ptr); \
169 break; \
170 case 8: \
171 __get_user_8(__ret_gu, __val_gu, ptr); \
172 break; \
173 default: \
174 __get_user_x(X, __ret_gu, __val_gu, ptr); \
175 break; \
176 } \
177 (x) = (__typeof__(*(ptr)))__val_gu; \
178 __ret_gu; \
179})
180
181#define __put_user_x(size, x, ptr, __ret_pu) \
182 asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
183 :"0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
184
185
186
187#ifdef CONFIG_X86_32
188#define __put_user_u64(x, addr, err) \
189 asm volatile("1: movl %%eax,0(%2)\n" \
190 "2: movl %%edx,4(%2)\n" \
191 "3:\n" \
192 ".section .fixup,\"ax\"\n" \
193 "4: movl %3,%0\n" \
194 " jmp 3b\n" \
195 ".previous\n" \
196 _ASM_EXTABLE(1b, 4b) \
197 _ASM_EXTABLE(2b, 4b) \
198 : "=r" (err) \
199 : "A" (x), "r" (addr), "i" (-EFAULT), "0" (err))
200
201#define __put_user_x8(x, ptr, __ret_pu) \
202 asm volatile("call __put_user_8" : "=a" (__ret_pu) \
203 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
204#else
205#define __put_user_u64(x, ptr, retval) \
206 __put_user_asm(x, ptr, retval, "q", "", "Zr", -EFAULT)
207#define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
208#endif
209
210extern void __put_user_bad(void);
211
212/*
213 * Strange magic calling convention: pointer in %ecx,
214 * value in %eax(:%edx), return value in %eax. clobbers %rbx
215 */
216extern void __put_user_1(void);
217extern void __put_user_2(void);
218extern void __put_user_4(void);
219extern void __put_user_8(void);
220
221#ifdef CONFIG_X86_WP_WORKS_OK
222
223/**
224 * put_user: - Write a simple value into user space.
225 * @x: Value to copy to user space.
226 * @ptr: Destination address, in user space.
227 *
228 * Context: User context only. This function may sleep.
229 *
230 * This macro copies a single simple value from kernel space to user
231 * space. It supports simple types like char and int, but not larger
232 * data types like structures or arrays.
233 *
234 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
235 * to the result of dereferencing @ptr.
236 *
237 * Returns zero on success, or -EFAULT on error.
238 */
239#define put_user(x, ptr) \
240({ \
241 int __ret_pu; \
242 __typeof__(*(ptr)) __pu_val; \
243 __chk_user_ptr(ptr); \
244 __pu_val = x; \
245 switch (sizeof(*(ptr))) { \
246 case 1: \
247 __put_user_x(1, __pu_val, ptr, __ret_pu); \
248 break; \
249 case 2: \
250 __put_user_x(2, __pu_val, ptr, __ret_pu); \
251 break; \
252 case 4: \
253 __put_user_x(4, __pu_val, ptr, __ret_pu); \
254 break; \
255 case 8: \
256 __put_user_x8(__pu_val, ptr, __ret_pu); \
257 break; \
258 default: \
259 __put_user_x(X, __pu_val, ptr, __ret_pu); \
260 break; \
261 } \
262 __ret_pu; \
263})
264
265#define __put_user_size(x, ptr, size, retval, errret) \
266do { \
267 retval = 0; \
268 __chk_user_ptr(ptr); \
269 switch (size) { \
270 case 1: \
271 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
272 break; \
273 case 2: \
274 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
275 break; \
276 case 4: \
277 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret);\
278 break; \
279 case 8: \
280 __put_user_u64((__typeof__(*ptr))(x), ptr, retval); \
281 break; \
282 default: \
283 __put_user_bad(); \
284 } \
285} while (0)
286
287#else
288
289#define __put_user_size(x, ptr, size, retval, errret) \
290do { \
291 __typeof__(*(ptr))__pus_tmp = x; \
292 retval = 0; \
293 \
294 if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0)) \
295 retval = errret; \
296} while (0)
297
298#define put_user(x, ptr) \
299({ \
300 int __ret_pu; \
301 __typeof__(*(ptr))__pus_tmp = x; \
302 __ret_pu = 0; \
303 if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, \
304 sizeof(*(ptr))) != 0)) \
305 __ret_pu = -EFAULT; \
306 __ret_pu; \
307})
308#endif
309
310#ifdef CONFIG_X86_32
311#define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad()
312#else
313#define __get_user_asm_u64(x, ptr, retval, errret) \
314 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
315#endif
316
317#define __get_user_size(x, ptr, size, retval, errret) \
318do { \
319 retval = 0; \
320 __chk_user_ptr(ptr); \
321 switch (size) { \
322 case 1: \
323 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
324 break; \
325 case 2: \
326 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
327 break; \
328 case 4: \
329 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
330 break; \
331 case 8: \
332 __get_user_asm_u64(x, ptr, retval, errret); \
333 break; \
334 default: \
335 (x) = __get_user_bad(); \
336 } \
337} while (0)
338
339#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
340 asm volatile("1: mov"itype" %2,%"rtype"1\n" \
341 "2:\n" \
342 ".section .fixup,\"ax\"\n" \
343 "3: mov %3,%0\n" \
344 " xor"itype" %"rtype"1,%"rtype"1\n" \
345 " jmp 2b\n" \
346 ".previous\n" \
347 _ASM_EXTABLE(1b, 3b) \
348 : "=r" (err), ltype(x) \
349 : "m" (__m(addr)), "i" (errret), "0" (err))
350
351#define __put_user_nocheck(x, ptr, size) \
352({ \
353 long __pu_err; \
354 __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
355 __pu_err; \
356})
357
358#define __get_user_nocheck(x, ptr, size) \
359({ \
360 long __gu_err; \
361 unsigned long __gu_val; \
362 __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
363 (x) = (__force __typeof__(*(ptr)))__gu_val; \
364 __gu_err; \
365})
366
367/* FIXME: this hack is definitely wrong -AK */
368struct __large_struct { unsigned long buf[100]; };
369#define __m(x) (*(struct __large_struct __user *)(x))
370
371/*
372 * Tell gcc we read from memory instead of writing: this is because
373 * we do not write to any memory gcc knows about, so there are no
374 * aliasing issues.
375 */
376#define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
377 asm volatile("1: mov"itype" %"rtype"1,%2\n" \
378 "2:\n" \
379 ".section .fixup,\"ax\"\n" \
380 "3: mov %3,%0\n" \
381 " jmp 2b\n" \
382 ".previous\n" \
383 _ASM_EXTABLE(1b, 3b) \
384 : "=r"(err) \
385 : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
386/**
387 * __get_user: - Get a simple variable from user space, with less checking.
388 * @x: Variable to store result.
389 * @ptr: Source address, in user space.
390 *
391 * Context: User context only. This function may sleep.
392 *
393 * This macro copies a single simple variable from user space to kernel
394 * space. It supports simple types like char and int, but not larger
395 * data types like structures or arrays.
396 *
397 * @ptr must have pointer-to-simple-variable type, and the result of
398 * dereferencing @ptr must be assignable to @x without a cast.
399 *
400 * Caller must check the pointer with access_ok() before calling this
401 * function.
402 *
403 * Returns zero on success, or -EFAULT on error.
404 * On error, the variable @x is set to zero.
405 */
406
407#define __get_user(x, ptr) \
408 __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
409/**
410 * __put_user: - Write a simple value into user space, with less checking.
411 * @x: Value to copy to user space.
412 * @ptr: Destination address, in user space.
413 *
414 * Context: User context only. This function may sleep.
415 *
416 * This macro copies a single simple value from kernel space to user
417 * space. It supports simple types like char and int, but not larger
418 * data types like structures or arrays.
419 *
420 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
421 * to the result of dereferencing @ptr.
422 *
423 * Caller must check the pointer with access_ok() before calling this
424 * function.
425 *
426 * Returns zero on success, or -EFAULT on error.
427 */
428
429#define __put_user(x, ptr) \
430 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
431
432#define __get_user_unaligned __get_user
433#define __put_user_unaligned __put_user
434
435/*
436 * movsl can be slow when source and dest are not both 8-byte aligned
437 */
438#ifdef CONFIG_X86_INTEL_USERCOPY
439extern struct movsl_mask {
440 int mask;
441} ____cacheline_aligned_in_smp movsl_mask;
442#endif
443
444#define ARCH_HAS_NOCACHE_UACCESS 1
445
446#ifdef CONFIG_X86_32
447# include "uaccess_32.h"
448#else
449# define ARCH_HAS_SEARCH_EXTABLE
450# include "uaccess_64.h"
451#endif
452
453#endif /* ASM_X86__UACCESS_H */
454
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