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uaccess.h
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1 #ifndef _ASM_IA64_UACCESS_H
2 #define _ASM_IA64_UACCESS_H
3 
4 /*
5  * This file defines various macros to transfer memory areas across
6  * the user/kernel boundary. This needs to be done carefully because
7  * this code is executed in kernel mode and uses user-specified
8  * addresses. Thus, we need to be careful not to let the user to
9  * trick us into accessing kernel memory that would normally be
10  * inaccessible. This code is also fairly performance sensitive,
11  * so we want to spend as little time doing safety checks as
12  * possible.
13  *
14  * To make matters a bit more interesting, these macros sometimes also
15  * called from within the kernel itself, in which case the address
16  * validity check must be skipped. The get_fs() macro tells us what
17  * to do: if get_fs()==USER_DS, checking is performed, if
18  * get_fs()==KERNEL_DS, checking is bypassed.
19  *
20  * Note that even if the memory area specified by the user is in a
21  * valid address range, it is still possible that we'll get a page
22  * fault while accessing it. This is handled by filling out an
23  * exception handler fixup entry for each instruction that has the
24  * potential to fault. When such a fault occurs, the page fault
25  * handler checks to see whether the faulting instruction has a fixup
26  * associated and, if so, sets r8 to -EFAULT and clears r9 to 0 and
27  * then resumes execution at the continuation point.
28  *
29  * Based on <asm-alpha/uaccess.h>.
30  *
31  * Copyright (C) 1998, 1999, 2001-2004 Hewlett-Packard Co
32  * David Mosberger-Tang <[email protected]>
33  */
34 
35 #include <linux/compiler.h>
36 #include <linux/errno.h>
37 #include <linux/sched.h>
38 #include <linux/page-flags.h>
39 #include <linux/mm.h>
40 
41 #include <asm/intrinsics.h>
42 #include <asm/pgtable.h>
43 #include <asm/io.h>
44 
45 /*
46  * For historical reasons, the following macros are grossly misnamed:
47  */
48 #define KERNEL_DS ((mm_segment_t) { ~0UL }) /* cf. access_ok() */
49 #define USER_DS ((mm_segment_t) { TASK_SIZE-1 }) /* cf. access_ok() */
50 
51 #define VERIFY_READ 0
52 #define VERIFY_WRITE 1
53 
54 #define get_ds() (KERNEL_DS)
55 #define get_fs() (current_thread_info()->addr_limit)
56 #define set_fs(x) (current_thread_info()->addr_limit = (x))
57 
58 #define segment_eq(a, b) ((a).seg == (b).seg)
59 
60 /*
61  * When accessing user memory, we need to make sure the entire area really is in
62  * user-level space. In order to do this efficiently, we make sure that the page at
63  * address TASK_SIZE is never valid. We also need to make sure that the address doesn't
64  * point inside the virtually mapped linear page table.
65  */
66 #define __access_ok(addr, size, segment) \
67 ({ \
68  __chk_user_ptr(addr); \
69  (likely((unsigned long) (addr) <= (segment).seg) \
70  && ((segment).seg == KERNEL_DS.seg \
71  || likely(REGION_OFFSET((unsigned long) (addr)) < RGN_MAP_LIMIT))); \
72 })
73 #define access_ok(type, addr, size) __access_ok((addr), (size), get_fs())
74 
75 /*
76  * These are the main single-value transfer routines. They automatically
77  * use the right size if we just have the right pointer type.
78  *
79  * Careful to not
80  * (a) re-use the arguments for side effects (sizeof/typeof is ok)
81  * (b) require any knowledge of processes at this stage
82  */
83 #define put_user(x, ptr) __put_user_check((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)), get_fs())
84 #define get_user(x, ptr) __get_user_check((x), (ptr), sizeof(*(ptr)), get_fs())
85 
86 /*
87  * The "__xxx" versions do not do address space checking, useful when
88  * doing multiple accesses to the same area (the programmer has to do the
89  * checks by hand with "access_ok()")
90  */
91 #define __put_user(x, ptr) __put_user_nocheck((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
92 #define __get_user(x, ptr) __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
93 
94 extern long __put_user_unaligned_unknown (void);
95 
96 #define __put_user_unaligned(x, ptr) \
97 ({ \
98  long __ret; \
99  switch (sizeof(*(ptr))) { \
100  case 1: __ret = __put_user((x), (ptr)); break; \
101  case 2: __ret = (__put_user((x), (u8 __user *)(ptr))) \
102  | (__put_user((x) >> 8, ((u8 __user *)(ptr) + 1))); break; \
103  case 4: __ret = (__put_user((x), (u16 __user *)(ptr))) \
104  | (__put_user((x) >> 16, ((u16 __user *)(ptr) + 1))); break; \
105  case 8: __ret = (__put_user((x), (u32 __user *)(ptr))) \
106  | (__put_user((x) >> 32, ((u32 __user *)(ptr) + 1))); break; \
107  default: __ret = __put_user_unaligned_unknown(); \
108  } \
109  __ret; \
110 })
111 
112 extern long __get_user_unaligned_unknown (void);
113 
114 #define __get_user_unaligned(x, ptr) \
115 ({ \
116  long __ret; \
117  switch (sizeof(*(ptr))) { \
118  case 1: __ret = __get_user((x), (ptr)); break; \
119  case 2: __ret = (__get_user((x), (u8 __user *)(ptr))) \
120  | (__get_user((x) >> 8, ((u8 __user *)(ptr) + 1))); break; \
121  case 4: __ret = (__get_user((x), (u16 __user *)(ptr))) \
122  | (__get_user((x) >> 16, ((u16 __user *)(ptr) + 1))); break; \
123  case 8: __ret = (__get_user((x), (u32 __user *)(ptr))) \
124  | (__get_user((x) >> 32, ((u32 __user *)(ptr) + 1))); break; \
125  default: __ret = __get_user_unaligned_unknown(); \
126  } \
127  __ret; \
128 })
129 
130 #ifdef ASM_SUPPORTED
131  struct __large_struct { unsigned long buf[100]; };
132 # define __m(x) (*(struct __large_struct __user *)(x))
133 
134 /* We need to declare the __ex_table section before we can use it in .xdata. */
135 asm (".section \"__ex_table\", \"a\"\n\t.previous");
136 
137 # define __get_user_size(val, addr, n, err) \
138 do { \
139  register long __gu_r8 asm ("r8") = 0; \
140  register long __gu_r9 asm ("r9"); \
141  asm ("\n[1:]\tld"#n" %0=%2%P2\t// %0 and %1 get overwritten by exception handler\n" \
142  "\t.xdata4 \"__ex_table\", 1b-., 1f-.+4\n" \
143  "[1:]" \
144  : "=r"(__gu_r9), "=r"(__gu_r8) : "m"(__m(addr)), "1"(__gu_r8)); \
145  (err) = __gu_r8; \
146  (val) = __gu_r9; \
147 } while (0)
148 
149 /*
150  * The "__put_user_size()" macro tells gcc it reads from memory instead of writing it. This
151  * is because they do not write to any memory gcc knows about, so there are no aliasing
152  * issues.
153  */
154 # define __put_user_size(val, addr, n, err) \
155 do { \
156  register long __pu_r8 asm ("r8") = 0; \
157  asm volatile ("\n[1:]\tst"#n" %1=%r2%P1\t// %0 gets overwritten by exception handler\n" \
158  "\t.xdata4 \"__ex_table\", 1b-., 1f-.\n" \
159  "[1:]" \
160  : "=r"(__pu_r8) : "m"(__m(addr)), "rO"(val), "0"(__pu_r8)); \
161  (err) = __pu_r8; \
162 } while (0)
163 
164 #else /* !ASM_SUPPORTED */
165 # define RELOC_TYPE 2 /* ip-rel */
166 # define __get_user_size(val, addr, n, err) \
167 do { \
168  __ld_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE); \
169  (err) = ia64_getreg(_IA64_REG_R8); \
170  (val) = ia64_getreg(_IA64_REG_R9); \
171 } while (0)
172 # define __put_user_size(val, addr, n, err) \
173 do { \
174  __st_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE, (unsigned long) (val)); \
175  (err) = ia64_getreg(_IA64_REG_R8); \
176 } while (0)
177 #endif /* !ASM_SUPPORTED */
178 
179 extern void __get_user_unknown (void);
180 
181 /*
182  * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
183  * could clobber r8 and r9 (among others). Thus, be careful not to evaluate it while
184  * using r8/r9.
185  */
186 #define __do_get_user(check, x, ptr, size, segment) \
187 ({ \
188  const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
189  __typeof__ (size) __gu_size = (size); \
190  long __gu_err = -EFAULT; \
191  unsigned long __gu_val = 0; \
192  if (!check || __access_ok(__gu_ptr, size, segment)) \
193  switch (__gu_size) { \
194  case 1: __get_user_size(__gu_val, __gu_ptr, 1, __gu_err); break; \
195  case 2: __get_user_size(__gu_val, __gu_ptr, 2, __gu_err); break; \
196  case 4: __get_user_size(__gu_val, __gu_ptr, 4, __gu_err); break; \
197  case 8: __get_user_size(__gu_val, __gu_ptr, 8, __gu_err); break; \
198  default: __get_user_unknown(); break; \
199  } \
200  (x) = (__typeof__(*(__gu_ptr))) __gu_val; \
201  __gu_err; \
202 })
203 
204 #define __get_user_nocheck(x, ptr, size) __do_get_user(0, x, ptr, size, KERNEL_DS)
205 #define __get_user_check(x, ptr, size, segment) __do_get_user(1, x, ptr, size, segment)
206 
207 extern void __put_user_unknown (void);
208 
209 /*
210  * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
211  * could clobber r8 (among others). Thus, be careful not to evaluate them while using r8.
212  */
213 #define __do_put_user(check, x, ptr, size, segment) \
214 ({ \
215  __typeof__ (x) __pu_x = (x); \
216  __typeof__ (*(ptr)) __user *__pu_ptr = (ptr); \
217  __typeof__ (size) __pu_size = (size); \
218  long __pu_err = -EFAULT; \
219  \
220  if (!check || __access_ok(__pu_ptr, __pu_size, segment)) \
221  switch (__pu_size) { \
222  case 1: __put_user_size(__pu_x, __pu_ptr, 1, __pu_err); break; \
223  case 2: __put_user_size(__pu_x, __pu_ptr, 2, __pu_err); break; \
224  case 4: __put_user_size(__pu_x, __pu_ptr, 4, __pu_err); break; \
225  case 8: __put_user_size(__pu_x, __pu_ptr, 8, __pu_err); break; \
226  default: __put_user_unknown(); break; \
227  } \
228  __pu_err; \
229 })
230 
231 #define __put_user_nocheck(x, ptr, size) __do_put_user(0, x, ptr, size, KERNEL_DS)
232 #define __put_user_check(x, ptr, size, segment) __do_put_user(1, x, ptr, size, segment)
233 
234 /*
235  * Complex access routines
236  */
237 extern unsigned long __must_check __copy_user (void __user *to, const void __user *from,
238  unsigned long count);
239 
240 static inline unsigned long
241 __copy_to_user (void __user *to, const void *from, unsigned long count)
242 {
243  return __copy_user(to, (__force void __user *) from, count);
244 }
245 
246 static inline unsigned long
247 __copy_from_user (void *to, const void __user *from, unsigned long count)
248 {
249  return __copy_user((__force void __user *) to, from, count);
250 }
251 
252 #define __copy_to_user_inatomic __copy_to_user
253 #define __copy_from_user_inatomic __copy_from_user
254 #define copy_to_user(to, from, n) \
255 ({ \
256  void __user *__cu_to = (to); \
257  const void *__cu_from = (from); \
258  long __cu_len = (n); \
259  \
260  if (__access_ok(__cu_to, __cu_len, get_fs())) \
261  __cu_len = __copy_user(__cu_to, (__force void __user *) __cu_from, __cu_len); \
262  __cu_len; \
263 })
264 
265 #define copy_from_user(to, from, n) \
266 ({ \
267  void *__cu_to = (to); \
268  const void __user *__cu_from = (from); \
269  long __cu_len = (n); \
270  \
271  __chk_user_ptr(__cu_from); \
272  if (__access_ok(__cu_from, __cu_len, get_fs())) \
273  __cu_len = __copy_user((__force void __user *) __cu_to, __cu_from, __cu_len); \
274  __cu_len; \
275 })
276 
277 #define __copy_in_user(to, from, size) __copy_user((to), (from), (size))
278 
279 static inline unsigned long
280 copy_in_user (void __user *to, const void __user *from, unsigned long n)
281 {
282  if (likely(access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n)))
283  n = __copy_user(to, from, n);
284  return n;
285 }
286 
287 extern unsigned long __do_clear_user (void __user *, unsigned long);
288 
289 #define __clear_user(to, n) __do_clear_user(to, n)
290 
291 #define clear_user(to, n) \
292 ({ \
293  unsigned long __cu_len = (n); \
294  if (__access_ok(to, __cu_len, get_fs())) \
295  __cu_len = __do_clear_user(to, __cu_len); \
296  __cu_len; \
297 })
298 
299 
300 /*
301  * Returns: -EFAULT if exception before terminator, N if the entire buffer filled, else
302  * strlen.
303  */
304 extern long __must_check __strncpy_from_user (char *to, const char __user *from, long to_len);
305 
306 #define strncpy_from_user(to, from, n) \
307 ({ \
308  const char __user * __sfu_from = (from); \
309  long __sfu_ret = -EFAULT; \
310  if (__access_ok(__sfu_from, 0, get_fs())) \
311  __sfu_ret = __strncpy_from_user((to), __sfu_from, (n)); \
312  __sfu_ret; \
313 })
314 
315 /* Returns: 0 if bad, string length+1 (memory size) of string if ok */
316 extern unsigned long __strlen_user (const char __user *);
317 
318 #define strlen_user(str) \
319 ({ \
320  const char __user *__su_str = (str); \
321  unsigned long __su_ret = 0; \
322  if (__access_ok(__su_str, 0, get_fs())) \
323  __su_ret = __strlen_user(__su_str); \
324  __su_ret; \
325 })
326 
327 /*
328  * Returns: 0 if exception before NUL or reaching the supplied limit
329  * (N), a value greater than N if the limit would be exceeded, else
330  * strlen.
331  */
332 extern unsigned long __strnlen_user (const char __user *, long);
333 
334 #define strnlen_user(str, len) \
335 ({ \
336  const char __user *__su_str = (str); \
337  unsigned long __su_ret = 0; \
338  if (__access_ok(__su_str, 0, get_fs())) \
339  __su_ret = __strnlen_user(__su_str, len); \
340  __su_ret; \
341 })
342 
343 /* Generic code can't deal with the location-relative format that we use for compactness. */
344 #define ARCH_HAS_SORT_EXTABLE
345 #define ARCH_HAS_SEARCH_EXTABLE
346 
347 struct exception_table_entry {
348  int addr; /* location-relative address of insn this fixup is for */
349  int cont; /* location-relative continuation addr.; if bit 2 is set, r9 is set to 0 */
350 };
351 
352 extern void ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e);
353 extern const struct exception_table_entry *search_exception_tables (unsigned long addr);
354 
355 static inline int
356 ia64_done_with_exception (struct pt_regs *regs)
357 {
358  const struct exception_table_entry *e;
359  e = search_exception_tables(regs->cr_iip + ia64_psr(regs)->ri);
360  if (e) {
361  ia64_handle_exception(regs, e);
362  return 1;
363  }
364  return 0;
365 }
366 
367 #define ARCH_HAS_TRANSLATE_MEM_PTR 1
368 static __inline__ char *
369 xlate_dev_mem_ptr (unsigned long p)
370 {
371  struct page *page;
372  char * ptr;
373 
374  page = pfn_to_page(p >> PAGE_SHIFT);
375  if (PageUncached(page))
376  ptr = (char *)p + __IA64_UNCACHED_OFFSET;
377  else
378  ptr = __va(p);
379 
380  return ptr;
381 }
382 
383 /*
384  * Convert a virtual cached kernel memory pointer to an uncached pointer
385  */
386 static __inline__ char *
387 xlate_dev_kmem_ptr (char * p)
388 {
389  struct page *page;
390  char * ptr;
391 
392  page = virt_to_page((unsigned long)p);
393  if (PageUncached(page))
394  ptr = (char *)__pa(p) + __IA64_UNCACHED_OFFSET;
395  else
396  ptr = p;
397 
398  return ptr;
399 }
400 
401 #endif /* _ASM_IA64_UACCESS_H */