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>
20 #include <linux/prefetch.h>
23 #define VERIFY_WRITE 1
27 #include <asm/current.h>
28 #include <asm/asm-offsets.h>
29 #include <asm/processor.h>
30 #include <asm/types.h>
33 * These assembly macros mirror the C macros that follow below. They
34 * should always have identical functionality. See
35 * arch/xtensa/kernel/sys.S for usage.
41 #define get_ds (KERNEL_DS)
44 * get_fs reads current->thread.current_ds into a register.
49 * <ad> contains current->thread.current_ds
53 l32i \ad, \ad, THREAD_CURRENT_DS
57 * set_fs sets current->thread.current_ds to some value.
59 * <at> anything (temp register)
63 * <at> destroyed (actually, current)
64 * <av> preserved, value to write
66 .macro set_fs at, av, sp
68 s32i \av, \at, THREAD_CURRENT_DS
72 * kernel_ok determines whether we should bypass addr/size checking.
73 * See the equivalent C-macro version below for clarity.
74 * On success, kernel_ok branches to a label indicated by parameter
75 * <success>. This implies that the macro falls through to the next
76 * insruction on an error.
78 * Note that while this macro can be used independently, we designed
79 * in for optimal use in the access_ok macro below (i.e., we fall
83 * <at> anything (temp register)
84 * <success> label to branch to on success; implies
85 * fall-through macro on error
88 * <at> destroyed (actually, current->thread.current_ds)
91 #if ((KERNEL_DS != 0) || (USER_DS == 0))
92 # error Assembly macro kernel_ok fails
94 .macro kernel_ok at, sp, success
100 * user_ok determines whether the access to user-space memory is allowed.
101 * See the equivalent C-macro version below for clarity.
103 * On error, user_ok branches to a label indicated by parameter
104 * <error>. This implies that the macro falls through to the next
105 * instruction on success.
107 * Note that while this macro can be used independently, we designed
108 * in for optimal use in the access_ok macro below (i.e., we fall
109 * through on success).
112 * <aa> register containing memory address
113 * <as> register containing memory size
115 * <error> label to branch to on error; implies fall-through
120 * <at> destroyed (actually, (TASK_SIZE + 1 - size))
122 .macro user_ok aa, as, at, error
123 movi \at, __XTENSA_UL_CONST(TASK_SIZE)
124 bgeu \as, \at, \error
126 bgeu \aa, \at, \error
130 * access_ok determines whether a memory access is allowed. See the
131 * equivalent C-macro version below for clarity.
133 * On error, access_ok branches to a label indicated by parameter
134 * <error>. This implies that the macro falls through to the next
135 * instruction on success.
137 * Note that we assume success is the common case, and we optimize the
138 * branch fall-through case on success.
141 * <aa> register containing memory address
142 * <as> register containing memory size
145 * <error> label to branch to on error; implies fall-through
152 .macro access_ok aa, as, at, sp, error
153 kernel_ok \at, \sp, .Laccess_ok_\@
154 user_ok \aa, \as, \at, \error
158 #else /* __ASSEMBLY__ not defined */
160 #include <linux/sched.h>
161 #include <asm/types.h>
164 * The fs value determines whether argument validity checking should
165 * be performed or not. If get_fs() == USER_DS, checking is
166 * performed, with get_fs() == KERNEL_DS, checking is bypassed.
168 * For historical reasons (Data Segment Register?), these macros are
172 #define KERNEL_DS ((mm_segment_t) { 0 })
173 #define USER_DS ((mm_segment_t) { 1 })
175 #define get_ds() (KERNEL_DS)
176 #define get_fs() (current->thread.current_ds)
177 #define set_fs(val) (current->thread.current_ds = (val))
179 #define segment_eq(a,b) ((a).seg == (b).seg)
181 #define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
182 #define __user_ok(addr,size) (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
183 #define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size)))
184 #define access_ok(type,addr,size) __access_ok((unsigned long)(addr),(size))
187 * These are the main single-value transfer routines. They
188 * automatically use the right size if we just have the right pointer
191 * This gets kind of ugly. We want to return _two_ values in
192 * "get_user()" and yet we don't want to do any pointers, because that
193 * is too much of a performance impact. Thus we have a few rather ugly
194 * macros here, and hide all the uglyness from the user.
197 * (a) re-use the arguments for side effects (sizeof is ok)
198 * (b) require any knowledge of processes at this stage
200 #define put_user(x,ptr) __put_user_check((x),(ptr),sizeof(*(ptr)))
201 #define get_user(x,ptr) __get_user_check((x),(ptr),sizeof(*(ptr)))
204 * The "__xxx" versions of the user access functions are versions that
205 * do not verify the address space, that must have been done previously
206 * with a separate "access_ok()" call (this is used when we do multiple
207 * accesses to the same area of user memory).
209 #define __put_user(x,ptr) __put_user_nocheck((x),(ptr),sizeof(*(ptr)))
210 #define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
213 extern long __put_user_bad(void);
215 #define __put_user_nocheck(x,ptr,size) \
218 __put_user_size((x),(ptr),(size),__pu_err); \
222 #define __put_user_check(x,ptr,size) \
224 long __pu_err = -EFAULT; \
225 __typeof__(*(ptr)) *__pu_addr = (ptr); \
226 if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
227 __put_user_size((x),__pu_addr,(size),__pu_err); \
231 #define __put_user_size(x,ptr,size,retval) \
236 case 1: __put_user_asm(x,ptr,retval,1,"s8i",__cb); break; \
237 case 2: __put_user_asm(x,ptr,retval,2,"s16i",__cb); break; \
238 case 4: __put_user_asm(x,ptr,retval,4,"s32i",__cb); break; \
240 __typeof__(*ptr) __v64 = x; \
241 retval = __copy_to_user(ptr,&__v64,8); \
244 default: __put_user_bad(); \
250 * Consider a case of a user single load/store would cause both an
251 * unaligned exception and an MMU-related exception (unaligned
252 * exceptions happen first):
254 * User code passes a bad variable ptr to a system call.
255 * Kernel tries to access the variable.
256 * Unaligned exception occurs.
257 * Unaligned exception handler tries to make aligned accesses.
258 * Double exception occurs for MMU-related cause (e.g., page not mapped).
259 * do_page_fault() thinks the fault address belongs to the kernel, not the
262 * The kernel currently prohibits user unaligned accesses. We use the
263 * __check_align_* macros to check for unaligned addresses before
264 * accessing user space so we don't crash the kernel. Both
265 * __put_user_asm and __get_user_asm use these alignment macros, so
266 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
270 #define __check_align_1 ""
272 #define __check_align_2 \
273 " _bbci.l %3, 0, 1f \n" \
277 #define __check_align_4 \
278 " _bbsi.l %3, 0, 0f \n" \
279 " _bbci.l %3, 1, 1f \n" \
280 "0: movi %0, %4 \n" \
285 * We don't tell gcc that we are accessing memory, but this is OK
286 * because we do not write to any memory gcc knows about, so there
287 * are no aliasing issues.
289 * WARNING: If you modify this macro at all, verify that the
290 * __check_align_* macros still work.
292 #define __put_user_asm(x, addr, err, align, insn, cb) \
293 __asm__ __volatile__( \
294 __check_align_##align \
295 "1: "insn" %2, %3, 0 \n" \
297 " .section .fixup,\"ax\" \n" \
306 " .section __ex_table,\"a\" \n" \
309 :"=r" (err), "=r" (cb) \
310 :"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err))
312 #define __get_user_nocheck(x,ptr,size) \
314 long __gu_err, __gu_val; \
315 __get_user_size(__gu_val,(ptr),(size),__gu_err); \
316 (x) = (__typeof__(*(ptr)))__gu_val; \
320 #define __get_user_check(x,ptr,size) \
322 long __gu_err = -EFAULT, __gu_val = 0; \
323 const __typeof__(*(ptr)) *__gu_addr = (ptr); \
324 if (access_ok(VERIFY_READ,__gu_addr,size)) \
325 __get_user_size(__gu_val,__gu_addr,(size),__gu_err); \
326 (x) = (__typeof__(*(ptr)))__gu_val; \
330 extern long __get_user_bad(void);
332 #define __get_user_size(x,ptr,size,retval) \
337 case 1: __get_user_asm(x,ptr,retval,1,"l8ui",__cb); break; \
338 case 2: __get_user_asm(x,ptr,retval,2,"l16ui",__cb); break; \
339 case 4: __get_user_asm(x,ptr,retval,4,"l32i",__cb); break; \
340 case 8: retval = __copy_from_user(&x,ptr,8); break; \
341 default: (x) = __get_user_bad(); \
347 * WARNING: If you modify this macro at all, verify that the
348 * __check_align_* macros still work.
350 #define __get_user_asm(x, addr, err, align, insn, cb) \
351 __asm__ __volatile__( \
352 __check_align_##align \
353 "1: "insn" %2, %3, 0 \n" \
355 " .section .fixup,\"ax\" \n" \
365 " .section __ex_table,\"a\" \n" \
368 :"=r" (err), "=r" (cb), "=r" (x) \
369 :"r" (addr), "i" (-EFAULT), "0" (err))
373 * Copy to/from user space
377 * We use a generic, arbitrary-sized copy subroutine. The Xtensa
378 * architecture would cause heavy code bloat if we tried to inline
379 * these functions and provide __constant_copy_* equivalents like the
380 * i386 versions. __xtensa_copy_user is quite efficient. See the
381 * .fixup section of __xtensa_copy_user for a discussion on the
382 * X_zeroing equivalents for Xtensa.
385 extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);
386 #define __copy_user(to,from,size) __xtensa_copy_user(to,from,size)
389 static inline unsigned long
390 __generic_copy_from_user_nocheck(void *to, const void *from, unsigned long n)
392 return __copy_user(to,from,n);
395 static inline unsigned long
396 __generic_copy_to_user_nocheck(void *to, const void *from, unsigned long n)
398 return __copy_user(to,from,n);
401 static inline unsigned long
402 __generic_copy_to_user(void *to, const void *from, unsigned long n)
405 if (access_ok(VERIFY_WRITE, to, n))
406 return __copy_user(to,from,n);
410 static inline unsigned long
411 __generic_copy_from_user(void *to, const void *from, unsigned long n)
414 if (access_ok(VERIFY_READ, from, n))
415 return __copy_user(to,from,n);
421 #define copy_to_user(to,from,n) __generic_copy_to_user((to),(from),(n))
422 #define copy_from_user(to,from,n) __generic_copy_from_user((to),(from),(n))
423 #define __copy_to_user(to,from,n) __generic_copy_to_user_nocheck((to),(from),(n))
424 #define __copy_from_user(to,from,n) __generic_copy_from_user_nocheck((to),(from),(n))
425 #define __copy_to_user_inatomic __copy_to_user
426 #define __copy_from_user_inatomic __copy_from_user
430 * We need to return the number of bytes not cleared. Our memset()
431 * returns zero if a problem occurs while accessing user-space memory.
432 * In that event, return no memory cleared. Otherwise, zero for
436 static inline unsigned long
437 __xtensa_clear_user(void *addr, unsigned long size)
439 if ( ! memset(addr, 0, size) )
444 static inline unsigned long
445 clear_user(void *addr, unsigned long size)
447 if (access_ok(VERIFY_WRITE, addr, size))
448 return __xtensa_clear_user(addr, size);
449 return size ? -EFAULT : 0;
452 #define __clear_user __xtensa_clear_user
455 extern long __strncpy_user(char *, const char *, long);
456 #define __strncpy_from_user __strncpy_user
459 strncpy_from_user(char *dst, const char *src, long count)
461 if (access_ok(VERIFY_READ, src, 1))
462 return __strncpy_from_user(dst, src, count);
467 #define strlen_user(str) strnlen_user((str), TASK_SIZE - 1)
470 * Return the size of a string (including the ending 0!)
472 extern long __strnlen_user(const char *, long);
474 static inline long strnlen_user(const char *str, long len)
476 unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1;
478 if ((unsigned long)str > top)
480 return __strnlen_user(str, len);
484 struct exception_table_entry
486 unsigned long insn, fixup;
489 /* Returns 0 if exception not found and fixup.unit otherwise. */
491 extern unsigned long search_exception_table(unsigned long addr);
492 extern void sort_exception_table(void);
494 /* Returns the new pc */
495 #define fixup_exception(map_reg, fixup_unit, pc) \
500 #endif /* __ASSEMBLY__ */
501 #endif /* _XTENSA_UACCESS_H */