1 #ifndef __i386_UACCESS_H
2 #define __i386_UACCESS_H
5 * User space memory access functions
7 #include <linux/config.h>
8 #include <linux/errno.h>
9 #include <linux/thread_info.h>
10 #include <linux/prefetch.h>
11 #include <linux/string.h>
15 #define VERIFY_WRITE 1
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.
22 * For historical reasons, these macros are grossly misnamed.
25 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
28 #define KERNEL_DS MAKE_MM_SEG(0xFFFFFFFFUL)
29 #define USER_DS MAKE_MM_SEG(PAGE_OFFSET)
31 #define get_ds() (KERNEL_DS)
32 #define get_fs() (current_thread_info()->addr_limit)
33 #define set_fs(x) (current_thread_info()->addr_limit = (x))
35 #define segment_eq(a,b) ((a).seg == (b).seg)
38 * movsl can be slow when source and dest are not both 8-byte aligned
40 #ifdef CONFIG_X86_INTEL_USERCOPY
41 extern struct movsl_mask {
43 } ____cacheline_aligned_in_smp movsl_mask;
46 #define __addr_ok(addr) ((unsigned long)(addr) < (current_thread_info()->addr_limit.seg))
49 * Test whether a block of memory is a valid user space address.
50 * Returns 0 if the range is valid, nonzero otherwise.
52 * This is equivalent to the following test:
53 * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
55 * This needs 33-bit arithmetic. We have a carry...
57 #define __range_ok(addr,size) ({ \
58 unsigned long flag,sum; \
59 asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
60 :"=&r" (flag), "=r" (sum) \
61 :"1" (addr),"g" ((int)(size)),"g" (current_thread_info()->addr_limit.seg)); \
65 * access_ok: - Checks if a user space pointer is valid
66 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
67 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
68 * to write to a block, it is always safe to read from it.
69 * @addr: User space pointer to start of block to check
70 * @size: Size of block to check
72 * Context: User context only. This function may sleep.
74 * Checks if a pointer to a block of memory in user space is valid.
76 * Returns true (nonzero) if the memory block may be valid, false (zero)
77 * if it is definitely invalid.
79 * Note that, depending on architecture, this function probably just
80 * checks that the pointer is in the user space range - after calling
81 * this function, memory access functions may still return -EFAULT.
83 #define access_ok(type,addr,size) (likely(__range_ok(addr,size) == 0))
86 * verify_area: - Obsolete, use access_ok()
87 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE
88 * @addr: User space pointer to start of block to check
89 * @size: Size of block to check
91 * Context: User context only. This function may sleep.
93 * This function has been replaced by access_ok().
95 * Checks if a pointer to a block of memory in user space is valid.
97 * Returns zero if the memory block may be valid, -EFAULT
98 * if it is definitely invalid.
100 * See access_ok() for more details.
102 static inline int verify_area(int type, const void __user * addr, unsigned long size)
104 return access_ok(type,addr,size) ? 0 : -EFAULT;
109 * The exception table consists of pairs of addresses: the first is the
110 * address of an instruction that is allowed to fault, and the second is
111 * the address at which the program should continue. No registers are
112 * modified, so it is entirely up to the continuation code to figure out
115 * All the routines below use bits of fixup code that are out of line
116 * with the main instruction path. This means when everything is well,
117 * we don't even have to jump over them. Further, they do not intrude
118 * on our cache or tlb entries.
121 struct exception_table_entry
123 unsigned long insn, fixup;
126 extern int fixup_exception(struct pt_regs *regs);
129 * These are the main single-value transfer routines. They automatically
130 * use the right size if we just have the right pointer type.
132 * This gets kind of ugly. We want to return _two_ values in "get_user()"
133 * and yet we don't want to do any pointers, because that is too much
134 * of a performance impact. Thus we have a few rather ugly macros here,
135 * and hide all the ugliness from the user.
137 * The "__xxx" versions of the user access functions are versions that
138 * do not verify the address space, that must have been done previously
139 * with a separate "access_ok()" call (this is used when we do multiple
140 * accesses to the same area of user memory).
143 extern void __get_user_1(void);
144 extern void __get_user_2(void);
145 extern void __get_user_4(void);
147 #define __get_user_x(size,ret,x,ptr) \
148 __asm__ __volatile__("call __get_user_" #size \
149 :"=a" (ret),"=d" (x) \
153 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
155 * get_user: - Get a simple variable from user space.
156 * @x: Variable to store result.
157 * @ptr: Source address, in user space.
159 * Context: User context only. This function may sleep.
161 * This macro copies a single simple variable from user space to kernel
162 * space. It supports simple types like char and int, but not larger
163 * data types like structures or arrays.
165 * @ptr must have pointer-to-simple-variable type, and the result of
166 * dereferencing @ptr must be assignable to @x without a cast.
168 * Returns zero on success, or -EFAULT on error.
169 * On error, the variable @x is set to zero.
171 #define get_user(x,ptr) \
172 ({ int __ret_gu,__val_gu; \
173 switch(sizeof (*(ptr))) { \
174 case 1: __get_user_x(1,__ret_gu,__val_gu,ptr); break; \
175 case 2: __get_user_x(2,__ret_gu,__val_gu,ptr); break; \
176 case 4: __get_user_x(4,__ret_gu,__val_gu,ptr); break; \
177 default: __get_user_x(X,__ret_gu,__val_gu,ptr); break; \
179 (x) = (__typeof__(*(ptr)))__val_gu; \
183 extern void __put_user_bad(void);
186 * put_user: - Write a simple value into user space.
187 * @x: Value to copy to user space.
188 * @ptr: Destination address, in user space.
190 * Context: User context only. This function may sleep.
192 * This macro copies a single simple value from kernel space to user
193 * space. It supports simple types like char and int, but not larger
194 * data types like structures or arrays.
196 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
197 * to the result of dereferencing @ptr.
199 * Returns zero on success, or -EFAULT on error.
201 #define put_user(x,ptr) \
202 __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
206 * __get_user: - Get a simple variable from user space, with less checking.
207 * @x: Variable to store result.
208 * @ptr: Source address, in user space.
210 * Context: User context only. This function may sleep.
212 * This macro copies a single simple variable from user space to kernel
213 * space. It supports simple types like char and int, but not larger
214 * data types like structures or arrays.
216 * @ptr must have pointer-to-simple-variable type, and the result of
217 * dereferencing @ptr must be assignable to @x without a cast.
219 * Caller must check the pointer with access_ok() before calling this
222 * Returns zero on success, or -EFAULT on error.
223 * On error, the variable @x is set to zero.
225 #define __get_user(x,ptr) \
226 __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
230 * __put_user: - Write a simple value into user space, with less checking.
231 * @x: Value to copy to user space.
232 * @ptr: Destination address, in user space.
234 * Context: User context only. This function may sleep.
236 * This macro copies a single simple value from kernel space to user
237 * space. It supports simple types like char and int, but not larger
238 * data types like structures or arrays.
240 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
241 * to the result of dereferencing @ptr.
243 * Caller must check the pointer with access_ok() before calling this
246 * Returns zero on success, or -EFAULT on error.
248 #define __put_user(x,ptr) \
249 __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
251 #define __put_user_nocheck(x,ptr,size) \
254 __put_user_size((x),(ptr),(size),__pu_err,-EFAULT); \
259 #define __put_user_check(x,ptr,size) \
261 long __pu_err = -EFAULT; \
262 __typeof__(*(ptr)) *__pu_addr = (ptr); \
264 if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
265 __put_user_size((x),__pu_addr,(size),__pu_err,-EFAULT); \
269 #define __put_user_u64(x, addr, err) \
270 __asm__ __volatile__( \
271 "1: movl %%eax,0(%2)\n" \
272 "2: movl %%edx,4(%2)\n" \
274 ".section .fixup,\"ax\"\n" \
278 ".section __ex_table,\"a\"\n" \
284 : "A" (x), "r" (addr), "i"(-EFAULT), "0"(err))
286 #ifdef CONFIG_X86_WP_WORKS_OK
288 #define __put_user_size(x,ptr,size,retval,errret) \
292 case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break; \
293 case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
294 case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break; \
295 case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
296 default: __put_user_bad(); \
302 #define __put_user_size(x,ptr,size,retval,errret) \
304 __typeof__(*(ptr)) __pus_tmp = x; \
307 if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0)) \
312 struct __large_struct { unsigned long buf[100]; };
313 #define __m(x) (*(struct __large_struct *)(x))
316 * Tell gcc we read from memory instead of writing: this is because
317 * we do not write to any memory gcc knows about, so there are no
320 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
321 __asm__ __volatile__( \
322 "1: mov"itype" %"rtype"1,%2\n" \
324 ".section .fixup,\"ax\"\n" \
328 ".section __ex_table,\"a\"\n" \
333 : ltype (x), "m"(__m(addr)), "i"(errret), "0"(err))
336 #define __get_user_nocheck(x,ptr,size) \
338 long __gu_err, __gu_val; \
339 __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
340 (x) = (__typeof__(*(ptr)))__gu_val; \
344 extern long __get_user_bad(void);
346 #define __get_user_size(x,ptr,size,retval,errret) \
350 case 1: __get_user_asm(x,ptr,retval,"b","b","=q",errret);break; \
351 case 2: __get_user_asm(x,ptr,retval,"w","w","=r",errret);break; \
352 case 4: __get_user_asm(x,ptr,retval,"l","","=r",errret);break; \
353 default: (x) = __get_user_bad(); \
357 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
358 __asm__ __volatile__( \
359 "1: mov"itype" %2,%"rtype"1\n" \
361 ".section .fixup,\"ax\"\n" \
363 " xor"itype" %"rtype"1,%"rtype"1\n" \
366 ".section __ex_table,\"a\"\n" \
370 : "=r"(err), ltype (x) \
371 : "m"(__m(addr)), "i"(errret), "0"(err))
374 unsigned long __copy_to_user_ll(void __user *to, const void *from, unsigned long n);
375 unsigned long __copy_from_user_ll(void *to, const void __user *from, unsigned long n);
378 * Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault
379 * we return the initial request size (1, 2 or 4), as copy_*_user should do.
380 * If a store crosses a page boundary and gets a fault, the x86 will not write
381 * anything, so this is accurate.
385 * __copy_to_user: - Copy a block of data into user space, with less checking.
386 * @to: Destination address, in user space.
387 * @from: Source address, in kernel space.
388 * @n: Number of bytes to copy.
390 * Context: User context only. This function may sleep.
392 * Copy data from kernel space to user space. Caller must check
393 * the specified block with access_ok() before calling this function.
395 * Returns number of bytes that could not be copied.
396 * On success, this will be zero.
398 static inline unsigned long
399 __copy_to_user(void __user *to, const void *from, unsigned long n)
401 if (__builtin_constant_p(n)) {
406 __put_user_size(*(u8 *)from, (u8 *)to, 1, ret, 1);
409 __put_user_size(*(u16 *)from, (u16 *)to, 2, ret, 2);
412 __put_user_size(*(u32 *)from, (u32 *)to, 4, ret, 4);
416 return __copy_to_user_ll(to, from, n);
420 * __copy_from_user: - Copy a block of data from user space, with less checking.
421 * @to: Destination address, in kernel space.
422 * @from: Source address, in user space.
423 * @n: Number of bytes to copy.
425 * Context: User context only. This function may sleep.
427 * Copy data from user space to kernel space. Caller must check
428 * the specified block with access_ok() before calling this function.
430 * Returns number of bytes that could not be copied.
431 * On success, this will be zero.
433 * If some data could not be copied, this function will pad the copied
434 * data to the requested size using zero bytes.
436 static inline unsigned long
437 __copy_from_user(void *to, const void __user *from, unsigned long n)
439 if (__builtin_constant_p(n)) {
444 __get_user_size(*(u8 *)to, from, 1, ret, 1);
447 __get_user_size(*(u16 *)to, from, 2, ret, 2);
450 __get_user_size(*(u32 *)to, from, 4, ret, 4);
454 return __copy_from_user_ll(to, from, n);
457 unsigned long copy_to_user(void __user *to, const void *from, unsigned long n);
458 unsigned long copy_from_user(void *to,
459 const void __user *from, unsigned long n);
460 long strncpy_from_user(char *dst, const char __user *src, long count);
461 long __strncpy_from_user(char *dst, const char __user *src, long count);
464 * strlen_user: - Get the size of a string in user space.
465 * @str: The string to measure.
467 * Context: User context only. This function may sleep.
469 * Get the size of a NUL-terminated string in user space.
471 * Returns the size of the string INCLUDING the terminating NUL.
472 * On exception, returns 0.
474 * If there is a limit on the length of a valid string, you may wish to
475 * consider using strnlen_user() instead.
477 #define strlen_user(str) strnlen_user(str, ~0UL >> 1)
479 long strnlen_user(const char __user *str, long n);
480 unsigned long clear_user(void __user *mem, unsigned long len);
481 unsigned long __clear_user(void __user *mem, unsigned long len);
483 #endif /* __i386_UACCESS_H */