xref: /openbmc/linux/arch/ia64/include/asm/uaccess.h (revision c819e2cf)
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 <davidm@hpl.hp.com>
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__ void *
369 xlate_dev_mem_ptr(phys_addr_t p)
370 {
371 	struct page *page;
372 	void *ptr;
373 
374 	page = pfn_to_page(p >> PAGE_SHIFT);
375 	if (PageUncached(page))
376 		ptr = (void *)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__ void *
387 xlate_dev_kmem_ptr(void *p)
388 {
389 	struct page *page;
390 	void *ptr;
391 
392 	page = virt_to_page((unsigned long)p);
393 	if (PageUncached(page))
394 		ptr = (void *)__pa(p) + __IA64_UNCACHED_OFFSET;
395 	else
396 		ptr = p;
397 
398 	return ptr;
399 }
400 
401 #endif /* _ASM_IA64_UACCESS_H */
402