xref: /openbmc/linux/arch/powerpc/include/asm/uaccess.h (revision 9ac8d3fb)
1 #ifndef _ARCH_POWERPC_UACCESS_H
2 #define _ARCH_POWERPC_UACCESS_H
3 
4 #ifdef __KERNEL__
5 #ifndef __ASSEMBLY__
6 
7 #include <linux/sched.h>
8 #include <linux/errno.h>
9 #include <asm/asm-compat.h>
10 #include <asm/processor.h>
11 #include <asm/page.h>
12 
13 #define VERIFY_READ	0
14 #define VERIFY_WRITE	1
15 
16 /*
17  * The fs value determines whether argument validity checking should be
18  * performed or not.  If get_fs() == USER_DS, checking is performed, with
19  * get_fs() == KERNEL_DS, checking is bypassed.
20  *
21  * For historical reasons, these macros are grossly misnamed.
22  *
23  * The fs/ds values are now the highest legal address in the "segment".
24  * This simplifies the checking in the routines below.
25  */
26 
27 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
28 
29 #define KERNEL_DS	MAKE_MM_SEG(~0UL)
30 #ifdef __powerpc64__
31 /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
32 #define USER_DS		MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
33 #else
34 #define USER_DS		MAKE_MM_SEG(TASK_SIZE - 1)
35 #endif
36 
37 #define get_ds()	(KERNEL_DS)
38 #define get_fs()	(current->thread.fs)
39 #define set_fs(val)	(current->thread.fs = (val))
40 
41 #define segment_eq(a, b)	((a).seg == (b).seg)
42 
43 #ifdef __powerpc64__
44 /*
45  * This check is sufficient because there is a large enough
46  * gap between user addresses and the kernel addresses
47  */
48 #define __access_ok(addr, size, segment)	\
49 	(((addr) <= (segment).seg) && ((size) <= (segment).seg))
50 
51 #else
52 
53 #define __access_ok(addr, size, segment)	\
54 	(((addr) <= (segment).seg) &&		\
55 	 (((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)))))
56 
57 #endif
58 
59 #define access_ok(type, addr, size)		\
60 	(__chk_user_ptr(addr),			\
61 	 __access_ok((__force unsigned long)(addr), (size), get_fs()))
62 
63 /*
64  * The exception table consists of pairs of addresses: the first is the
65  * address of an instruction that is allowed to fault, and the second is
66  * the address at which the program should continue.  No registers are
67  * modified, so it is entirely up to the continuation code to figure out
68  * what to do.
69  *
70  * All the routines below use bits of fixup code that are out of line
71  * with the main instruction path.  This means when everything is well,
72  * we don't even have to jump over them.  Further, they do not intrude
73  * on our cache or tlb entries.
74  */
75 
76 struct exception_table_entry {
77 	unsigned long insn;
78 	unsigned long fixup;
79 };
80 
81 /*
82  * These are the main single-value transfer routines.  They automatically
83  * use the right size if we just have the right pointer type.
84  *
85  * This gets kind of ugly. We want to return _two_ values in "get_user()"
86  * and yet we don't want to do any pointers, because that is too much
87  * of a performance impact. Thus we have a few rather ugly macros here,
88  * and hide all the ugliness from the user.
89  *
90  * The "__xxx" versions of the user access functions are versions that
91  * do not verify the address space, that must have been done previously
92  * with a separate "access_ok()" call (this is used when we do multiple
93  * accesses to the same area of user memory).
94  *
95  * As we use the same address space for kernel and user data on the
96  * PowerPC, we can just do these as direct assignments.  (Of course, the
97  * exception handling means that it's no longer "just"...)
98  *
99  * The "user64" versions of the user access functions are versions that
100  * allow access of 64-bit data. The "get_user" functions do not
101  * properly handle 64-bit data because the value gets down cast to a long.
102  * The "put_user" functions already handle 64-bit data properly but we add
103  * "user64" versions for completeness
104  */
105 #define get_user(x, ptr) \
106 	__get_user_check((x), (ptr), sizeof(*(ptr)))
107 #define put_user(x, ptr) \
108 	__put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
109 
110 #define __get_user(x, ptr) \
111 	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
112 #define __put_user(x, ptr) \
113 	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
114 
115 #ifndef __powerpc64__
116 #define __get_user64(x, ptr) \
117 	__get_user64_nocheck((x), (ptr), sizeof(*(ptr)))
118 #define __put_user64(x, ptr) __put_user(x, ptr)
119 #endif
120 
121 #define __get_user_inatomic(x, ptr) \
122 	__get_user_nosleep((x), (ptr), sizeof(*(ptr)))
123 #define __put_user_inatomic(x, ptr) \
124 	__put_user_nosleep((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
125 
126 #define __get_user_unaligned __get_user
127 #define __put_user_unaligned __put_user
128 
129 extern long __put_user_bad(void);
130 
131 /*
132  * We don't tell gcc that we are accessing memory, but this is OK
133  * because we do not write to any memory gcc knows about, so there
134  * are no aliasing issues.
135  */
136 #define __put_user_asm(x, addr, err, op)			\
137 	__asm__ __volatile__(					\
138 		"1:	" op " %1,0(%2)	# put_user\n"		\
139 		"2:\n"						\
140 		".section .fixup,\"ax\"\n"			\
141 		"3:	li %0,%3\n"				\
142 		"	b 2b\n"					\
143 		".previous\n"					\
144 		".section __ex_table,\"a\"\n"			\
145 			PPC_LONG_ALIGN "\n"			\
146 			PPC_LONG "1b,3b\n"			\
147 		".previous"					\
148 		: "=r" (err)					\
149 		: "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
150 
151 #ifdef __powerpc64__
152 #define __put_user_asm2(x, ptr, retval)				\
153 	  __put_user_asm(x, ptr, retval, "std")
154 #else /* __powerpc64__ */
155 #define __put_user_asm2(x, addr, err)				\
156 	__asm__ __volatile__(					\
157 		"1:	stw %1,0(%2)\n"				\
158 		"2:	stw %1+1,4(%2)\n"			\
159 		"3:\n"						\
160 		".section .fixup,\"ax\"\n"			\
161 		"4:	li %0,%3\n"				\
162 		"	b 3b\n"					\
163 		".previous\n"					\
164 		".section __ex_table,\"a\"\n"			\
165 			PPC_LONG_ALIGN "\n"			\
166 			PPC_LONG "1b,4b\n"			\
167 			PPC_LONG "2b,4b\n"			\
168 		".previous"					\
169 		: "=r" (err)					\
170 		: "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
171 #endif /* __powerpc64__ */
172 
173 #define __put_user_size(x, ptr, size, retval)			\
174 do {								\
175 	retval = 0;						\
176 	switch (size) {						\
177 	  case 1: __put_user_asm(x, ptr, retval, "stb"); break;	\
178 	  case 2: __put_user_asm(x, ptr, retval, "sth"); break;	\
179 	  case 4: __put_user_asm(x, ptr, retval, "stw"); break;	\
180 	  case 8: __put_user_asm2(x, ptr, retval); break;	\
181 	  default: __put_user_bad();				\
182 	}							\
183 } while (0)
184 
185 #define __put_user_nocheck(x, ptr, size)			\
186 ({								\
187 	long __pu_err;						\
188 	__typeof__(*(ptr)) __user *__pu_addr = (ptr);		\
189 	if (!is_kernel_addr((unsigned long)__pu_addr))		\
190 		might_sleep();					\
191 	__chk_user_ptr(ptr);					\
192 	__put_user_size((x), __pu_addr, (size), __pu_err);	\
193 	__pu_err;						\
194 })
195 
196 #define __put_user_check(x, ptr, size)					\
197 ({									\
198 	long __pu_err = -EFAULT;					\
199 	__typeof__(*(ptr)) __user *__pu_addr = (ptr);			\
200 	might_sleep();							\
201 	if (access_ok(VERIFY_WRITE, __pu_addr, size))			\
202 		__put_user_size((x), __pu_addr, (size), __pu_err);	\
203 	__pu_err;							\
204 })
205 
206 #define __put_user_nosleep(x, ptr, size)			\
207 ({								\
208 	long __pu_err;						\
209 	__typeof__(*(ptr)) __user *__pu_addr = (ptr);		\
210 	__chk_user_ptr(ptr);					\
211 	__put_user_size((x), __pu_addr, (size), __pu_err);	\
212 	__pu_err;						\
213 })
214 
215 
216 extern long __get_user_bad(void);
217 
218 #define __get_user_asm(x, addr, err, op)		\
219 	__asm__ __volatile__(				\
220 		"1:	"op" %1,0(%2)	# get_user\n"	\
221 		"2:\n"					\
222 		".section .fixup,\"ax\"\n"		\
223 		"3:	li %0,%3\n"			\
224 		"	li %1,0\n"			\
225 		"	b 2b\n"				\
226 		".previous\n"				\
227 		".section __ex_table,\"a\"\n"		\
228 			PPC_LONG_ALIGN "\n"		\
229 			PPC_LONG "1b,3b\n"		\
230 		".previous"				\
231 		: "=r" (err), "=r" (x)			\
232 		: "b" (addr), "i" (-EFAULT), "0" (err))
233 
234 #ifdef __powerpc64__
235 #define __get_user_asm2(x, addr, err)			\
236 	__get_user_asm(x, addr, err, "ld")
237 #else /* __powerpc64__ */
238 #define __get_user_asm2(x, addr, err)			\
239 	__asm__ __volatile__(				\
240 		"1:	lwz %1,0(%2)\n"			\
241 		"2:	lwz %1+1,4(%2)\n"		\
242 		"3:\n"					\
243 		".section .fixup,\"ax\"\n"		\
244 		"4:	li %0,%3\n"			\
245 		"	li %1,0\n"			\
246 		"	li %1+1,0\n"			\
247 		"	b 3b\n"				\
248 		".previous\n"				\
249 		".section __ex_table,\"a\"\n"		\
250 			PPC_LONG_ALIGN "\n"		\
251 			PPC_LONG "1b,4b\n"		\
252 			PPC_LONG "2b,4b\n"		\
253 		".previous"				\
254 		: "=r" (err), "=&r" (x)			\
255 		: "b" (addr), "i" (-EFAULT), "0" (err))
256 #endif /* __powerpc64__ */
257 
258 #define __get_user_size(x, ptr, size, retval)			\
259 do {								\
260 	retval = 0;						\
261 	__chk_user_ptr(ptr);					\
262 	if (size > sizeof(x))					\
263 		(x) = __get_user_bad();				\
264 	switch (size) {						\
265 	case 1: __get_user_asm(x, ptr, retval, "lbz"); break;	\
266 	case 2: __get_user_asm(x, ptr, retval, "lhz"); break;	\
267 	case 4: __get_user_asm(x, ptr, retval, "lwz"); break;	\
268 	case 8: __get_user_asm2(x, ptr, retval);  break;	\
269 	default: (x) = __get_user_bad();			\
270 	}							\
271 } while (0)
272 
273 #define __get_user_nocheck(x, ptr, size)			\
274 ({								\
275 	long __gu_err;						\
276 	unsigned long __gu_val;					\
277 	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
278 	__chk_user_ptr(ptr);					\
279 	if (!is_kernel_addr((unsigned long)__gu_addr))		\
280 		might_sleep();					\
281 	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
282 	(x) = (__typeof__(*(ptr)))__gu_val;			\
283 	__gu_err;						\
284 })
285 
286 #ifndef __powerpc64__
287 #define __get_user64_nocheck(x, ptr, size)			\
288 ({								\
289 	long __gu_err;						\
290 	long long __gu_val;					\
291 	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
292 	__chk_user_ptr(ptr);					\
293 	if (!is_kernel_addr((unsigned long)__gu_addr))		\
294 		might_sleep();					\
295 	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
296 	(x) = (__typeof__(*(ptr)))__gu_val;			\
297 	__gu_err;						\
298 })
299 #endif /* __powerpc64__ */
300 
301 #define __get_user_check(x, ptr, size)					\
302 ({									\
303 	long __gu_err = -EFAULT;					\
304 	unsigned long  __gu_val = 0;					\
305 	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);		\
306 	might_sleep();							\
307 	if (access_ok(VERIFY_READ, __gu_addr, (size)))			\
308 		__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
309 	(x) = (__typeof__(*(ptr)))__gu_val;				\
310 	__gu_err;							\
311 })
312 
313 #define __get_user_nosleep(x, ptr, size)			\
314 ({								\
315 	long __gu_err;						\
316 	unsigned long __gu_val;					\
317 	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
318 	__chk_user_ptr(ptr);					\
319 	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
320 	(x) = (__typeof__(*(ptr)))__gu_val;			\
321 	__gu_err;						\
322 })
323 
324 
325 /* more complex routines */
326 
327 extern unsigned long __copy_tofrom_user(void __user *to,
328 		const void __user *from, unsigned long size);
329 
330 #ifndef __powerpc64__
331 
332 static inline unsigned long copy_from_user(void *to,
333 		const void __user *from, unsigned long n)
334 {
335 	unsigned long over;
336 
337 	if (access_ok(VERIFY_READ, from, n))
338 		return __copy_tofrom_user((__force void __user *)to, from, n);
339 	if ((unsigned long)from < TASK_SIZE) {
340 		over = (unsigned long)from + n - TASK_SIZE;
341 		return __copy_tofrom_user((__force void __user *)to, from,
342 				n - over) + over;
343 	}
344 	return n;
345 }
346 
347 static inline unsigned long copy_to_user(void __user *to,
348 		const void *from, unsigned long n)
349 {
350 	unsigned long over;
351 
352 	if (access_ok(VERIFY_WRITE, to, n))
353 		return __copy_tofrom_user(to, (__force void __user *)from, n);
354 	if ((unsigned long)to < TASK_SIZE) {
355 		over = (unsigned long)to + n - TASK_SIZE;
356 		return __copy_tofrom_user(to, (__force void __user *)from,
357 				n - over) + over;
358 	}
359 	return n;
360 }
361 
362 #else /* __powerpc64__ */
363 
364 #define __copy_in_user(to, from, size) \
365 	__copy_tofrom_user((to), (from), (size))
366 
367 extern unsigned long copy_from_user(void *to, const void __user *from,
368 				    unsigned long n);
369 extern unsigned long copy_to_user(void __user *to, const void *from,
370 				  unsigned long n);
371 extern unsigned long copy_in_user(void __user *to, const void __user *from,
372 				  unsigned long n);
373 
374 #endif /* __powerpc64__ */
375 
376 static inline unsigned long __copy_from_user_inatomic(void *to,
377 		const void __user *from, unsigned long n)
378 {
379 	if (__builtin_constant_p(n) && (n <= 8)) {
380 		unsigned long ret = 1;
381 
382 		switch (n) {
383 		case 1:
384 			__get_user_size(*(u8 *)to, from, 1, ret);
385 			break;
386 		case 2:
387 			__get_user_size(*(u16 *)to, from, 2, ret);
388 			break;
389 		case 4:
390 			__get_user_size(*(u32 *)to, from, 4, ret);
391 			break;
392 		case 8:
393 			__get_user_size(*(u64 *)to, from, 8, ret);
394 			break;
395 		}
396 		if (ret == 0)
397 			return 0;
398 	}
399 	return __copy_tofrom_user((__force void __user *)to, from, n);
400 }
401 
402 static inline unsigned long __copy_to_user_inatomic(void __user *to,
403 		const void *from, unsigned long n)
404 {
405 	if (__builtin_constant_p(n) && (n <= 8)) {
406 		unsigned long ret = 1;
407 
408 		switch (n) {
409 		case 1:
410 			__put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret);
411 			break;
412 		case 2:
413 			__put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret);
414 			break;
415 		case 4:
416 			__put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret);
417 			break;
418 		case 8:
419 			__put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret);
420 			break;
421 		}
422 		if (ret == 0)
423 			return 0;
424 	}
425 	return __copy_tofrom_user(to, (__force const void __user *)from, n);
426 }
427 
428 static inline unsigned long __copy_from_user(void *to,
429 		const void __user *from, unsigned long size)
430 {
431 	might_sleep();
432 	return __copy_from_user_inatomic(to, from, size);
433 }
434 
435 static inline unsigned long __copy_to_user(void __user *to,
436 		const void *from, unsigned long size)
437 {
438 	might_sleep();
439 	return __copy_to_user_inatomic(to, from, size);
440 }
441 
442 extern unsigned long __clear_user(void __user *addr, unsigned long size);
443 
444 static inline unsigned long clear_user(void __user *addr, unsigned long size)
445 {
446 	might_sleep();
447 	if (likely(access_ok(VERIFY_WRITE, addr, size)))
448 		return __clear_user(addr, size);
449 	if ((unsigned long)addr < TASK_SIZE) {
450 		unsigned long over = (unsigned long)addr + size - TASK_SIZE;
451 		return __clear_user(addr, size - over) + over;
452 	}
453 	return size;
454 }
455 
456 extern int __strncpy_from_user(char *dst, const char __user *src, long count);
457 
458 static inline long strncpy_from_user(char *dst, const char __user *src,
459 		long count)
460 {
461 	might_sleep();
462 	if (likely(access_ok(VERIFY_READ, src, 1)))
463 		return __strncpy_from_user(dst, src, count);
464 	return -EFAULT;
465 }
466 
467 /*
468  * Return the size of a string (including the ending 0)
469  *
470  * Return 0 for error
471  */
472 extern int __strnlen_user(const char __user *str, long len, unsigned long top);
473 
474 /*
475  * Returns the length of the string at str (including the null byte),
476  * or 0 if we hit a page we can't access,
477  * or something > len if we didn't find a null byte.
478  *
479  * The `top' parameter to __strnlen_user is to make sure that
480  * we can never overflow from the user area into kernel space.
481  */
482 static inline int strnlen_user(const char __user *str, long len)
483 {
484 	unsigned long top = current->thread.fs.seg;
485 
486 	if ((unsigned long)str > top)
487 		return 0;
488 	return __strnlen_user(str, len, top);
489 }
490 
491 #define strlen_user(str)	strnlen_user((str), 0x7ffffffe)
492 
493 #endif  /* __ASSEMBLY__ */
494 #endif /* __KERNEL__ */
495 
496 #endif	/* _ARCH_POWERPC_UACCESS_H */
497