2 * include/asm-xtensa/uaccess.h
4 * User space memory access functions
6 * These routines provide basic accessing functions to the user memory
7 * space for the kernel. This header file provides functions such as:
9 * This file is subject to the terms and conditions of the GNU General Public
10 * License. See the file "COPYING" in the main directory of this archive
13 * Copyright (C) 2001 - 2005 Tensilica Inc.
16 #ifndef _XTENSA_UACCESS_H
17 #define _XTENSA_UACCESS_H
19 #include <linux/errno.h>
21 #include <linux/prefetch.h>
23 #include <asm/types.h>
26 #define VERIFY_WRITE 1
30 #include <asm/current.h>
31 #include <asm/asm-offsets.h>
32 #include <asm/processor.h>
35 * These assembly macros mirror the C macros that follow below. They
36 * should always have identical functionality. See
37 * arch/xtensa/kernel/sys.S for usage.
43 #define get_ds (KERNEL_DS)
46 * get_fs reads current->thread.current_ds into a register.
51 * <ad> contains current->thread.current_ds
55 #if THREAD_CURRENT_DS > 1020
56 addi \ad, \ad, TASK_THREAD
57 l32i \ad, \ad, THREAD_CURRENT_DS - TASK_THREAD
59 l32i \ad, \ad, THREAD_CURRENT_DS
64 * set_fs sets current->thread.current_ds to some value.
66 * <at> anything (temp register)
70 * <at> destroyed (actually, current)
71 * <av> preserved, value to write
73 .macro set_fs at, av, sp
75 s32i \av, \at, THREAD_CURRENT_DS
79 * kernel_ok determines whether we should bypass addr/size checking.
80 * See the equivalent C-macro version below for clarity.
81 * On success, kernel_ok branches to a label indicated by parameter
82 * <success>. This implies that the macro falls through to the next
83 * insruction on an error.
85 * Note that while this macro can be used independently, we designed
86 * in for optimal use in the access_ok macro below (i.e., we fall
90 * <at> anything (temp register)
91 * <success> label to branch to on success; implies
92 * fall-through macro on error
95 * <at> destroyed (actually, current->thread.current_ds)
98 #if ((KERNEL_DS != 0) || (USER_DS == 0))
99 # error Assembly macro kernel_ok fails
101 .macro kernel_ok at, sp, success
107 * user_ok determines whether the access to user-space memory is allowed.
108 * See the equivalent C-macro version below for clarity.
110 * On error, user_ok branches to a label indicated by parameter
111 * <error>. This implies that the macro falls through to the next
112 * instruction on success.
114 * Note that while this macro can be used independently, we designed
115 * in for optimal use in the access_ok macro below (i.e., we fall
116 * through on success).
119 * <aa> register containing memory address
120 * <as> register containing memory size
122 * <error> label to branch to on error; implies fall-through
127 * <at> destroyed (actually, (TASK_SIZE + 1 - size))
129 .macro user_ok aa, as, at, error
130 movi \at, __XTENSA_UL_CONST(TASK_SIZE)
131 bgeu \as, \at, \error
133 bgeu \aa, \at, \error
137 * access_ok determines whether a memory access is allowed. See the
138 * equivalent C-macro version below for clarity.
140 * On error, access_ok branches to a label indicated by parameter
141 * <error>. This implies that the macro falls through to the next
142 * instruction on success.
144 * Note that we assume success is the common case, and we optimize the
145 * branch fall-through case on success.
148 * <aa> register containing memory address
149 * <as> register containing memory size
152 * <error> label to branch to on error; implies fall-through
159 .macro access_ok aa, as, at, sp, error
160 kernel_ok \at, \sp, .Laccess_ok_\@
161 user_ok \aa, \as, \at, \error
165 #else /* __ASSEMBLY__ not defined */
167 #include <linux/sched.h>
170 * The fs value determines whether argument validity checking should
171 * be performed or not. If get_fs() == USER_DS, checking is
172 * performed, with get_fs() == KERNEL_DS, checking is bypassed.
174 * For historical reasons (Data Segment Register?), these macros are
178 #define KERNEL_DS ((mm_segment_t) { 0 })
179 #define USER_DS ((mm_segment_t) { 1 })
181 #define get_ds() (KERNEL_DS)
182 #define get_fs() (current->thread.current_ds)
183 #define set_fs(val) (current->thread.current_ds = (val))
185 #define segment_eq(a,b) ((a).seg == (b).seg)
187 #define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
188 #define __user_ok(addr,size) \
189 (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
190 #define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size)))
191 #define access_ok(type,addr,size) __access_ok((unsigned long)(addr),(size))
194 * These are the main single-value transfer routines. They
195 * automatically use the right size if we just have the right pointer
198 * This gets kind of ugly. We want to return _two_ values in
199 * "get_user()" and yet we don't want to do any pointers, because that
200 * is too much of a performance impact. Thus we have a few rather ugly
201 * macros here, and hide all the uglyness from the user.
204 * (a) re-use the arguments for side effects (sizeof is ok)
205 * (b) require any knowledge of processes at this stage
207 #define put_user(x,ptr) __put_user_check((x),(ptr),sizeof(*(ptr)))
208 #define get_user(x,ptr) __get_user_check((x),(ptr),sizeof(*(ptr)))
211 * The "__xxx" versions of the user access functions are versions that
212 * do not verify the address space, that must have been done previously
213 * with a separate "access_ok()" call (this is used when we do multiple
214 * accesses to the same area of user memory).
216 #define __put_user(x,ptr) __put_user_nocheck((x),(ptr),sizeof(*(ptr)))
217 #define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
220 extern long __put_user_bad(void);
222 #define __put_user_nocheck(x,ptr,size) \
225 __put_user_size((x),(ptr),(size),__pu_err); \
229 #define __put_user_check(x,ptr,size) \
231 long __pu_err = -EFAULT; \
232 __typeof__(*(ptr)) *__pu_addr = (ptr); \
233 if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
234 __put_user_size((x),__pu_addr,(size),__pu_err); \
238 #define __put_user_size(x,ptr,size,retval) \
243 case 1: __put_user_asm(x,ptr,retval,1,"s8i",__cb); break; \
244 case 2: __put_user_asm(x,ptr,retval,2,"s16i",__cb); break; \
245 case 4: __put_user_asm(x,ptr,retval,4,"s32i",__cb); break; \
247 __typeof__(*ptr) __v64 = x; \
248 retval = __copy_to_user(ptr,&__v64,8); \
251 default: __put_user_bad(); \
257 * Consider a case of a user single load/store would cause both an
258 * unaligned exception and an MMU-related exception (unaligned
259 * exceptions happen first):
261 * User code passes a bad variable ptr to a system call.
262 * Kernel tries to access the variable.
263 * Unaligned exception occurs.
264 * Unaligned exception handler tries to make aligned accesses.
265 * Double exception occurs for MMU-related cause (e.g., page not mapped).
266 * do_page_fault() thinks the fault address belongs to the kernel, not the
269 * The kernel currently prohibits user unaligned accesses. We use the
270 * __check_align_* macros to check for unaligned addresses before
271 * accessing user space so we don't crash the kernel. Both
272 * __put_user_asm and __get_user_asm use these alignment macros, so
273 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
277 #define __check_align_1 ""
279 #define __check_align_2 \
280 " _bbci.l %3, 0, 1f \n" \
284 #define __check_align_4 \
285 " _bbsi.l %3, 0, 0f \n" \
286 " _bbci.l %3, 1, 1f \n" \
287 "0: movi %0, %4 \n" \
292 * We don't tell gcc that we are accessing memory, but this is OK
293 * because we do not write to any memory gcc knows about, so there
294 * are no aliasing issues.
296 * WARNING: If you modify this macro at all, verify that the
297 * __check_align_* macros still work.
299 #define __put_user_asm(x, addr, err, align, insn, cb) \
300 __asm__ __volatile__( \
301 __check_align_##align \
302 "1: "insn" %2, %3, 0 \n" \
304 " .section .fixup,\"ax\" \n" \
313 " .section __ex_table,\"a\" \n" \
316 :"=r" (err), "=r" (cb) \
317 :"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err))
319 #define __get_user_nocheck(x,ptr,size) \
321 long __gu_err, __gu_val; \
322 __get_user_size(__gu_val,(ptr),(size),__gu_err); \
323 (x) = (__typeof__(*(ptr)))__gu_val; \
327 #define __get_user_check(x,ptr,size) \
329 long __gu_err = -EFAULT, __gu_val = 0; \
330 const __typeof__(*(ptr)) *__gu_addr = (ptr); \
331 if (access_ok(VERIFY_READ,__gu_addr,size)) \
332 __get_user_size(__gu_val,__gu_addr,(size),__gu_err); \
333 (x) = (__typeof__(*(ptr)))__gu_val; \
337 extern long __get_user_bad(void);
339 #define __get_user_size(x,ptr,size,retval) \
344 case 1: __get_user_asm(x,ptr,retval,1,"l8ui",__cb); break; \
345 case 2: __get_user_asm(x,ptr,retval,2,"l16ui",__cb); break; \
346 case 4: __get_user_asm(x,ptr,retval,4,"l32i",__cb); break; \
347 case 8: retval = __copy_from_user(&x,ptr,8); break; \
348 default: (x) = __get_user_bad(); \
354 * WARNING: If you modify this macro at all, verify that the
355 * __check_align_* macros still work.
357 #define __get_user_asm(x, addr, err, align, insn, cb) \
358 __asm__ __volatile__( \
359 __check_align_##align \
360 "1: "insn" %2, %3, 0 \n" \
362 " .section .fixup,\"ax\" \n" \
372 " .section __ex_table,\"a\" \n" \
375 :"=r" (err), "=r" (cb), "=r" (x) \
376 :"r" (addr), "i" (-EFAULT), "0" (err))
380 * Copy to/from user space
384 * We use a generic, arbitrary-sized copy subroutine. The Xtensa
385 * architecture would cause heavy code bloat if we tried to inline
386 * these functions and provide __constant_copy_* equivalents like the
387 * i386 versions. __xtensa_copy_user is quite efficient. See the
388 * .fixup section of __xtensa_copy_user for a discussion on the
389 * X_zeroing equivalents for Xtensa.
392 extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);
393 #define __copy_user(to,from,size) __xtensa_copy_user(to,from,size)
396 static inline unsigned long
397 __generic_copy_from_user_nocheck(void *to, const void *from, unsigned long n)
399 return __copy_user(to,from,n);
402 static inline unsigned long
403 __generic_copy_to_user_nocheck(void *to, const void *from, unsigned long n)
405 return __copy_user(to,from,n);
408 static inline unsigned long
409 __generic_copy_to_user(void *to, const void *from, unsigned long n)
412 if (access_ok(VERIFY_WRITE, to, n))
413 return __copy_user(to,from,n);
417 static inline unsigned long
418 __generic_copy_from_user(void *to, const void *from, unsigned long n)
421 if (access_ok(VERIFY_READ, from, n))
422 return __copy_user(to,from,n);
428 #define copy_to_user(to,from,n) __generic_copy_to_user((to),(from),(n))
429 #define copy_from_user(to,from,n) __generic_copy_from_user((to),(from),(n))
430 #define __copy_to_user(to,from,n) \
431 __generic_copy_to_user_nocheck((to),(from),(n))
432 #define __copy_from_user(to,from,n) \
433 __generic_copy_from_user_nocheck((to),(from),(n))
434 #define __copy_to_user_inatomic __copy_to_user
435 #define __copy_from_user_inatomic __copy_from_user
439 * We need to return the number of bytes not cleared. Our memset()
440 * returns zero if a problem occurs while accessing user-space memory.
441 * In that event, return no memory cleared. Otherwise, zero for
445 static inline unsigned long
446 __xtensa_clear_user(void *addr, unsigned long size)
448 if ( ! memset(addr, 0, size) )
453 static inline unsigned long
454 clear_user(void *addr, unsigned long size)
456 if (access_ok(VERIFY_WRITE, addr, size))
457 return __xtensa_clear_user(addr, size);
458 return size ? -EFAULT : 0;
461 #define __clear_user __xtensa_clear_user
464 extern long __strncpy_user(char *, const char *, long);
465 #define __strncpy_from_user __strncpy_user
468 strncpy_from_user(char *dst, const char *src, long count)
470 if (access_ok(VERIFY_READ, src, 1))
471 return __strncpy_from_user(dst, src, count);
476 #define strlen_user(str) strnlen_user((str), TASK_SIZE - 1)
479 * Return the size of a string (including the ending 0!)
481 extern long __strnlen_user(const char *, long);
483 static inline long strnlen_user(const char *str, long len)
485 unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1;
487 if ((unsigned long)str > top)
489 return __strnlen_user(str, len);
493 struct exception_table_entry
495 unsigned long insn, fixup;
498 /* Returns 0 if exception not found and fixup.unit otherwise. */
500 extern unsigned long search_exception_table(unsigned long addr);
501 extern void sort_exception_table(void);
503 /* Returns the new pc */
504 #define fixup_exception(map_reg, fixup_unit, pc) \
509 #endif /* __ASSEMBLY__ */
510 #endif /* _XTENSA_UACCESS_H */