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diff --git a/include/asm-xtensa/uaccess.h b/include/asm-xtensa/uaccess.h
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1/*
2 * include/asm-xtensa/uaccess.h
3 *
4 * User space memory access functions
5 *
6 * These routines provide basic accessing functions to the user memory
7 * space for the kernel. This header file provides fuctions such as:
8 *
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
11 * for more details.
12 *
13 * Copyright (C) 2001 - 2005 Tensilica Inc.
14 */
15
16#ifndef _XTENSA_UACCESS_H
17#define _XTENSA_UACCESS_H
18
19#include <linux/errno.h>
20
21#define VERIFY_READ 0
22#define VERIFY_WRITE 1
23
24#ifdef __ASSEMBLY__
25
26#include <asm/current.h>
27#include <asm/asm-offsets.h>
28#include <asm/processor.h>
29#include <asm/types.h>
30
31/*
32 * These assembly macros mirror the C macros that follow below. They
33 * should always have identical functionality. See
34 * arch/xtensa/kernel/sys.S for usage.
35 */
36
37#define KERNEL_DS 0
38#define USER_DS 1
39
40#define get_ds (KERNEL_DS)
41
42/*
43 * get_fs reads current->thread.current_ds into a register.
44 * On Entry:
45 * <ad> anything
46 * <sp> stack
47 * On Exit:
48 * <ad> contains current->thread.current_ds
49 */
50 .macro get_fs ad, sp
51 GET_CURRENT(\ad,\sp)
52 l32i \ad, \ad, THREAD_CURRENT_DS
53 .endm
54
55/*
56 * set_fs sets current->thread.current_ds to some value.
57 * On Entry:
58 * <at> anything (temp register)
59 * <av> value to write
60 * <sp> stack
61 * On Exit:
62 * <at> destroyed (actually, current)
63 * <av> preserved, value to write
64 */
65 .macro set_fs at, av, sp
66 GET_CURRENT(\at,\sp)
67 s32i \av, \at, THREAD_CURRENT_DS
68 .endm
69
70/*
71 * kernel_ok determines whether we should bypass addr/size checking.
72 * See the equivalent C-macro version below for clarity.
73 * On success, kernel_ok branches to a label indicated by parameter
74 * <success>. This implies that the macro falls through to the next
75 * insruction on an error.
76 *
77 * Note that while this macro can be used independently, we designed
78 * in for optimal use in the access_ok macro below (i.e., we fall
79 * through on error).
80 *
81 * On Entry:
82 * <at> anything (temp register)
83 * <success> label to branch to on success; implies
84 * fall-through macro on error
85 * <sp> stack pointer
86 * On Exit:
87 * <at> destroyed (actually, current->thread.current_ds)
88 */
89
90#if ((KERNEL_DS != 0) || (USER_DS == 0))
91# error Assembly macro kernel_ok fails
92#endif
93 .macro kernel_ok at, sp, success
94 get_fs \at, \sp
95 beqz \at, \success
96 .endm
97
98/*
99 * user_ok determines whether the access to user-space memory is allowed.
100 * See the equivalent C-macro version below for clarity.
101 *
102 * On error, user_ok branches to a label indicated by parameter
103 * <error>. This implies that the macro falls through to the next
104 * instruction on success.
105 *
106 * Note that while this macro can be used independently, we designed
107 * in for optimal use in the access_ok macro below (i.e., we fall
108 * through on success).
109 *
110 * On Entry:
111 * <aa> register containing memory address
112 * <as> register containing memory size
113 * <at> temp register
114 * <error> label to branch to on error; implies fall-through
115 * macro on success
116 * On Exit:
117 * <aa> preserved
118 * <as> preserved
119 * <at> destroyed (actually, (TASK_SIZE + 1 - size))
120 */
121 .macro user_ok aa, as, at, error
122 movi \at, __XTENSA_UL_CONST(TASK_SIZE)
123 bgeu \as, \at, \error
124 sub \at, \at, \as
125 bgeu \aa, \at, \error
126 .endm
127
128/*
129 * access_ok determines whether a memory access is allowed. See the
130 * equivalent C-macro version below for clarity.
131 *
132 * On error, access_ok branches to a label indicated by parameter
133 * <error>. This implies that the macro falls through to the next
134 * instruction on success.
135 *
136 * Note that we assume success is the common case, and we optimize the
137 * branch fall-through case on success.
138 *
139 * On Entry:
140 * <aa> register containing memory address
141 * <as> register containing memory size
142 * <at> temp register
143 * <sp>
144 * <error> label to branch to on error; implies fall-through
145 * macro on success
146 * On Exit:
147 * <aa> preserved
148 * <as> preserved
149 * <at> destroyed
150 */
151 .macro access_ok aa, as, at, sp, error
152 kernel_ok \at, \sp, .Laccess_ok_\@
153 user_ok \aa, \as, \at, \error
154.Laccess_ok_\@:
155 .endm
156
157#else /* __ASSEMBLY__ not defined */
158
159#include <linux/sched.h>
160#include <asm/types.h>
161
162/*
163 * The fs value determines whether argument validity checking should
164 * be performed or not. If get_fs() == USER_DS, checking is
165 * performed, with get_fs() == KERNEL_DS, checking is bypassed.
166 *
167 * For historical reasons (Data Segment Register?), these macros are
168 * grossly misnamed.
169 */
170
171#define KERNEL_DS ((mm_segment_t) { 0 })
172#define USER_DS ((mm_segment_t) { 1 })
173
174#define get_ds() (KERNEL_DS)
175#define get_fs() (current->thread.current_ds)
176#define set_fs(val) (current->thread.current_ds = (val))
177
178#define segment_eq(a,b) ((a).seg == (b).seg)
179
180#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
181#define __user_ok(addr,size) (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
182#define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size)))
183#define access_ok(type,addr,size) __access_ok((unsigned long)(addr),(size))
184
185/*
186 * These are the main single-value transfer routines. They
187 * automatically use the right size if we just have the right pointer
188 * type.
189 *
190 * This gets kind of ugly. We want to return _two_ values in
191 * "get_user()" and yet we don't want to do any pointers, because that
192 * is too much of a performance impact. Thus we have a few rather ugly
193 * macros here, and hide all the uglyness from the user.
194 *
195 * Careful to not
196 * (a) re-use the arguments for side effects (sizeof is ok)
197 * (b) require any knowledge of processes at this stage
198 */
199#define put_user(x,ptr) __put_user_check((x),(ptr),sizeof(*(ptr)))
200#define get_user(x,ptr) __get_user_check((x),(ptr),sizeof(*(ptr)))
201
202/*
203 * The "__xxx" versions of the user access functions are versions that
204 * do not verify the address space, that must have been done previously
205 * with a separate "access_ok()" call (this is used when we do multiple
206 * accesses to the same area of user memory).
207 */
208#define __put_user(x,ptr) __put_user_nocheck((x),(ptr),sizeof(*(ptr)))
209#define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
210
211
212extern long __put_user_bad(void);
213
214#define __put_user_nocheck(x,ptr,size) \
215({ \
216 long __pu_err; \
217 __put_user_size((x),(ptr),(size),__pu_err); \
218 __pu_err; \
219})
220
221#define __put_user_check(x,ptr,size) \
222({ \
223 long __pu_err = -EFAULT; \
224 __typeof__(*(ptr)) *__pu_addr = (ptr); \
225 if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
226 __put_user_size((x),__pu_addr,(size),__pu_err); \
227 __pu_err; \
228})
229
230#define __put_user_size(x,ptr,size,retval) \
231do { \
232 int __cb; \
233 retval = 0; \
234 switch (size) { \
235 case 1: __put_user_asm(x,ptr,retval,1,"s8i",__cb); break; \
236 case 2: __put_user_asm(x,ptr,retval,2,"s16i",__cb); break; \
237 case 4: __put_user_asm(x,ptr,retval,4,"s32i",__cb); break; \
238 case 8: { \
239 __typeof__(*ptr) __v64 = x; \
240 retval = __copy_to_user(ptr,&__v64,8); \
241 break; \
242 } \
243 default: __put_user_bad(); \
244 } \
245} while (0)
246
247
248/*
249 * Consider a case of a user single load/store would cause both an
250 * unaligned exception and an MMU-related exception (unaligned
251 * exceptions happen first):
252 *
253 * User code passes a bad variable ptr to a system call.
254 * Kernel tries to access the variable.
255 * Unaligned exception occurs.
256 * Unaligned exception handler tries to make aligned accesses.
257 * Double exception occurs for MMU-related cause (e.g., page not mapped).
258 * do_page_fault() thinks the fault address belongs to the kernel, not the
259 * user, and panics.
260 *
261 * The kernel currently prohibits user unaligned accesses. We use the
262 * __check_align_* macros to check for unaligned addresses before
263 * accessing user space so we don't crash the kernel. Both
264 * __put_user_asm and __get_user_asm use these alignment macros, so
265 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
266 * sync.
267 */
268
269#define __check_align_1 ""
270
271#define __check_align_2 \
272 " _bbci.l %3, 0, 1f \n" \
273 " movi %0, %4 \n" \
274 " _j 2f \n"
275
276#define __check_align_4 \
277 " _bbsi.l %3, 0, 0f \n" \
278 " _bbci.l %3, 1, 1f \n" \
279 "0: movi %0, %4 \n" \
280 " _j 2f \n"
281
282
283/*
284 * We don't tell gcc that we are accessing memory, but this is OK
285 * because we do not write to any memory gcc knows about, so there
286 * are no aliasing issues.
287 *
288 * WARNING: If you modify this macro at all, verify that the
289 * __check_align_* macros still work.
290 */
291#define __put_user_asm(x, addr, err, align, insn, cb) \
292 __asm__ __volatile__( \
293 __check_align_##align \
294 "1: "insn" %2, %3, 0 \n" \
295 "2: \n" \
296 " .section .fixup,\"ax\" \n" \
297 " .align 4 \n" \
298 "4: \n" \
299 " .long 2b \n" \
300 "5: \n" \
301 " l32r %1, 4b \n" \
302 " movi %0, %4 \n" \
303 " jx %1 \n" \
304 " .previous \n" \
305 " .section __ex_table,\"a\" \n" \
306 " .long 1b, 5b \n" \
307 " .previous" \
308 :"=r" (err), "=r" (cb) \
309 :"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err))
310
311#define __get_user_nocheck(x,ptr,size) \
312({ \
313 long __gu_err, __gu_val; \
314 __get_user_size(__gu_val,(ptr),(size),__gu_err); \
315 (x) = (__typeof__(*(ptr)))__gu_val; \
316 __gu_err; \
317})
318
319#define __get_user_check(x,ptr,size) \
320({ \
321 long __gu_err = -EFAULT, __gu_val = 0; \
322 const __typeof__(*(ptr)) *__gu_addr = (ptr); \
323 if (access_ok(VERIFY_READ,__gu_addr,size)) \
324 __get_user_size(__gu_val,__gu_addr,(size),__gu_err); \
325 (x) = (__typeof__(*(ptr)))__gu_val; \
326 __gu_err; \
327})
328
329extern long __get_user_bad(void);
330
331#define __get_user_size(x,ptr,size,retval) \
332do { \
333 int __cb; \
334 retval = 0; \
335 switch (size) { \
336 case 1: __get_user_asm(x,ptr,retval,1,"l8ui",__cb); break; \
337 case 2: __get_user_asm(x,ptr,retval,2,"l16ui",__cb); break; \
338 case 4: __get_user_asm(x,ptr,retval,4,"l32i",__cb); break; \
339 case 8: retval = __copy_from_user(&x,ptr,8); break; \
340 default: (x) = __get_user_bad(); \
341 } \
342} while (0)
343
344
345/*
346 * WARNING: If you modify this macro at all, verify that the
347 * __check_align_* macros still work.
348 */
349#define __get_user_asm(x, addr, err, align, insn, cb) \
350 __asm__ __volatile__( \
351 __check_align_##align \
352 "1: "insn" %2, %3, 0 \n" \
353 "2: \n" \
354 " .section .fixup,\"ax\" \n" \
355 " .align 4 \n" \
356 "4: \n" \
357 " .long 2b \n" \
358 "5: \n" \
359 " l32r %1, 4b \n" \
360 " movi %2, 0 \n" \
361 " movi %0, %4 \n" \
362 " jx %1 \n" \
363 " .previous \n" \
364 " .section __ex_table,\"a\" \n" \
365 " .long 1b, 5b \n" \
366 " .previous" \
367 :"=r" (err), "=r" (cb), "=r" (x) \
368 :"r" (addr), "i" (-EFAULT), "0" (err))
369
370
371/*
372 * Copy to/from user space
373 */
374
375/*
376 * We use a generic, arbitrary-sized copy subroutine. The Xtensa
377 * architecture would cause heavy code bloat if we tried to inline
378 * these functions and provide __constant_copy_* equivalents like the
379 * i386 versions. __xtensa_copy_user is quite efficient. See the
380 * .fixup section of __xtensa_copy_user for a discussion on the
381 * X_zeroing equivalents for Xtensa.
382 */
383
384extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);
385#define __copy_user(to,from,size) __xtensa_copy_user(to,from,size)
386
387
388static inline unsigned long
389__generic_copy_from_user_nocheck(void *to, const void *from, unsigned long n)
390{
391 return __copy_user(to,from,n);
392}
393
394static inline unsigned long
395__generic_copy_to_user_nocheck(void *to, const void *from, unsigned long n)
396{
397 return __copy_user(to,from,n);
398}
399
400static inline unsigned long
401__generic_copy_to_user(void *to, const void *from, unsigned long n)
402{
403 prefetch(from);
404 if (access_ok(VERIFY_WRITE, to, n))
405 return __copy_user(to,from,n);
406 return n;
407}
408
409static inline unsigned long
410__generic_copy_from_user(void *to, const void *from, unsigned long n)
411{
412 prefetchw(to);
413 if (access_ok(VERIFY_READ, from, n))
414 return __copy_user(to,from,n);
415 else
416 memset(to, 0, n);
417 return n;
418}
419
420#define copy_to_user(to,from,n) __generic_copy_to_user((to),(from),(n))
421#define copy_from_user(to,from,n) __generic_copy_from_user((to),(from),(n))
422#define __copy_to_user(to,from,n) __generic_copy_to_user_nocheck((to),(from),(n))
423#define __copy_from_user(to,from,n) __generic_copy_from_user_nocheck((to),(from),(n))
424#define __copy_to_user_inatomic __copy_to_user
425#define __copy_from_user_inatomic __copy_from_user
426
427
428/*
429 * We need to return the number of bytes not cleared. Our memset()
430 * returns zero if a problem occurs while accessing user-space memory.
431 * In that event, return no memory cleared. Otherwise, zero for
432 * success.
433 */
434
435static inline unsigned long
436__xtensa_clear_user(void *addr, unsigned long size)
437{
438 if ( ! memset(addr, 0, size) )
439 return size;
440 return 0;
441}
442
443static inline unsigned long
444clear_user(void *addr, unsigned long size)
445{
446 if (access_ok(VERIFY_WRITE, addr, size))
447 return __xtensa_clear_user(addr, size);
448 return size ? -EFAULT : 0;
449}
450
451#define __clear_user __xtensa_clear_user
452
453
454extern long __strncpy_user(char *, const char *, long);
455#define __strncpy_from_user __strncpy_user
456
457static inline long
458strncpy_from_user(char *dst, const char *src, long count)
459{
460 if (access_ok(VERIFY_READ, src, 1))
461 return __strncpy_from_user(dst, src, count);
462 return -EFAULT;
463}
464
465
466#define strlen_user(str) strnlen_user((str), TASK_SIZE - 1)
467
468/*
469 * Return the size of a string (including the ending 0!)
470 */
471extern long __strnlen_user(const char *, long);
472
473static inline long strnlen_user(const char *str, long len)
474{
475 unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1;
476
477 if ((unsigned long)str > top)
478 return 0;
479 return __strnlen_user(str, len);
480}
481
482
483struct exception_table_entry
484{
485 unsigned long insn, fixup;
486};
487
488/* Returns 0 if exception not found and fixup.unit otherwise. */
489
490extern unsigned long search_exception_table(unsigned long addr);
491extern void sort_exception_table(void);
492
493/* Returns the new pc */
494#define fixup_exception(map_reg, fixup_unit, pc) \
495({ \
496 fixup_unit; \
497})
498
499#endif /* __ASSEMBLY__ */
500#endif /* _XTENSA_UACCESS_H */
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