[deliverable/linux.git] / include / asm-s390 / uaccess.h

/*
 *  include/asm-s390/uaccess.h
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Hartmut Penner (hp@de.ibm.com),
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 *  Derived from "include/asm-i386/uaccess.h"
 */
#ifndef __S390_UACCESS_H
#define __S390_UACCESS_H

/*
 * User space memory access functions
 */
#include <linux/sched.h>
#include <linux/errno.h>

#define VERIFY_READ     0
#define VERIFY_WRITE    1


/*
 * The fs value determines whether argument validity checking should be
 * performed or not.  If get_fs() == USER_DS, checking is performed, with
 * get_fs() == KERNEL_DS, checking is bypassed.
 *
 * For historical reasons, these macros are grossly misnamed.
 */

#define MAKE_MM_SEG(a)  ((mm_segment_t) { (a) })


#define KERNEL_DS       MAKE_MM_SEG(0)
#define USER_DS         MAKE_MM_SEG(1)

#define get_ds()        (KERNEL_DS)
#define get_fs()        (current->thread.mm_segment)

#ifdef __s390x__
#define set_fs(x) \
({									\
	unsigned long __pto;						\
	current->thread.mm_segment = (x);				\
	__pto = current->thread.mm_segment.ar4 ?			\
		S390_lowcore.user_asce : S390_lowcore.kernel_asce;	\
	asm volatile ("lctlg 7,7,%0" : : "m" (__pto) );			\
})
#else
#define set_fs(x) \
({									\
	unsigned long __pto;						\
	current->thread.mm_segment = (x);				\
	__pto = current->thread.mm_segment.ar4 ?			\
		S390_lowcore.user_asce : S390_lowcore.kernel_asce;	\
	asm volatile ("lctl  7,7,%0" : : "m" (__pto) );			\
})
#endif

#define segment_eq(a,b) ((a).ar4 == (b).ar4)


#define __access_ok(addr,size) (1)

#define access_ok(type,addr,size) __access_ok(addr,size)

/*
 * The exception table consists of pairs of addresses: the first is the
 * address of an instruction that is allowed to fault, and the second is
 * the address at which the program should continue.  No registers are
 * modified, so it is entirely up to the continuation code to figure out
 * what to do.
 *
 * All the routines below use bits of fixup code that are out of line
 * with the main instruction path.  This means when everything is well,
 * we don't even have to jump over them.  Further, they do not intrude
 * on our cache or tlb entries.
 */

struct exception_table_entry
{
        unsigned long insn, fixup;
};

#ifndef __s390x__
#define __uaccess_fixup \
	".section .fixup,\"ax\"\n"	\
	"2: lhi    %0,%4\n"		\
	"   bras   1,3f\n"		\
	"   .long  1b\n"		\
	"3: l      1,0(1)\n"		\
	"   br     1\n"			\
	".previous\n"			\
	".section __ex_table,\"a\"\n"	\
	"   .align 4\n"			\
	"   .long  0b,2b\n"		\
	".previous"
#define __uaccess_clobber "cc", "1"
#else /* __s390x__ */
#define __uaccess_fixup \
	".section .fixup,\"ax\"\n"	\
	"2: lghi   %0,%4\n"		\
	"   jg     1b\n"		\
	".previous\n"			\
	".section __ex_table,\"a\"\n"	\
	"   .align 8\n"			\
	"   .quad  0b,2b\n"		\
	".previous"
#define __uaccess_clobber "cc"
#endif /* __s390x__ */

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 */
#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
#define __put_user_asm(x, ptr, err) \
({								\
	err = 0;						\
	asm volatile(						\
		"0: mvcs  0(%1,%2),%3,%0\n"			\
		"1:\n"						\
		__uaccess_fixup					\
		: "+&d" (err)					\
		: "d" (sizeof(*(ptr))), "a" (ptr), "Q" (x),	\
		  "K" (-EFAULT)					\
		: __uaccess_clobber );				\
})
#else
#define __put_user_asm(x, ptr, err) \
({								\
	err = 0;						\
	asm volatile(						\
		"0: mvcs  0(%1,%2),0(%3),%0\n"			\
		"1:\n"						\
		__uaccess_fixup					\
		: "+&d" (err)					\
		: "d" (sizeof(*(ptr))), "a" (ptr), "a" (&(x)),	\
		  "K" (-EFAULT), "m" (x)			\
		: __uaccess_clobber );				\
})
#endif

#define __put_user(x, ptr) \
({								\
	__typeof__(*(ptr)) __x = (x);				\
	int __pu_err;						\
        __chk_user_ptr(ptr);                                    \
	switch (sizeof (*(ptr))) {				\
	case 1:							\
	case 2:							\
	case 4:							\
	case 8:							\
		__put_user_asm(__x, ptr, __pu_err);		\
		break;						\
	default:						\
		__put_user_bad();				\
		break;						\
	 }							\
	__pu_err;						\
})

#define put_user(x, ptr)					\
({								\
	might_sleep();						\
	__put_user(x, ptr);					\
})


extern int __put_user_bad(void) __attribute__((noreturn));

#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
#define __get_user_asm(x, ptr, err) \
({								\
	err = 0;						\
	asm volatile (						\
		"0: mvcp  %O1(%2,%R1),0(%3),%0\n"		\
		"1:\n"						\
		__uaccess_fixup					\
		: "+&d" (err), "=Q" (x)				\
		: "d" (sizeof(*(ptr))), "a" (ptr),		\
		  "K" (-EFAULT)					\
		: __uaccess_clobber );				\
})
#else
#define __get_user_asm(x, ptr, err) \
({								\
	err = 0;						\
	asm volatile (						\
		"0: mvcp  0(%2,%5),0(%3),%0\n"			\
		"1:\n"						\
		__uaccess_fixup					\
		: "+&d" (err), "=m" (x)				\
		: "d" (sizeof(*(ptr))), "a" (ptr),		\
		  "K" (-EFAULT), "a" (&(x))			\
		: __uaccess_clobber );				\
})
#endif

#define __get_user(x, ptr)					\
({								\
	__typeof__(*(ptr)) __x;					\
	int __gu_err;						\
        __chk_user_ptr(ptr);                                    \
	switch (sizeof(*(ptr))) {				\
	case 1:							\
	case 2:							\
	case 4:							\
	case 8:							\
		__get_user_asm(__x, ptr, __gu_err);		\
		break;						\
	default:						\
		__get_user_bad();				\
		break;						\
	}							\
	(x) = __x;						\
	__gu_err;						\
})

#define get_user(x, ptr)					\
({								\
	might_sleep();						\
	__get_user(x, ptr);					\
})

extern int __get_user_bad(void) __attribute__((noreturn));

#define __put_user_unaligned __put_user
#define __get_user_unaligned __get_user

extern long __copy_to_user_asm(const void *from, long n, void __user *to);

/**
 * __copy_to_user: - Copy a block of data into user space, with less checking.
 * @to:   Destination address, in user space.
 * @from: Source address, in kernel space.
 * @n:    Number of bytes to copy.
 *
 * Context: User context only.  This function may sleep.
 *
 * Copy data from kernel space to user space.  Caller must check
 * the specified block with access_ok() before calling this function.
 *
 * Returns number of bytes that could not be copied.
 * On success, this will be zero.
 */
static inline unsigned long
__copy_to_user(void __user *to, const void *from, unsigned long n)
{
	return __copy_to_user_asm(from, n, to);
}

#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user

/**
 * copy_to_user: - Copy a block of data into user space.
 * @to:   Destination address, in user space.
 * @from: Source address, in kernel space.
 * @n:    Number of bytes to copy.
 *
 * Context: User context only.  This function may sleep.
 *
 * Copy data from kernel space to user space.
 *
 * Returns number of bytes that could not be copied.
 * On success, this will be zero.
 */
static inline unsigned long
copy_to_user(void __user *to, const void *from, unsigned long n)
{
	might_sleep();
	if (access_ok(VERIFY_WRITE, to, n))
		n = __copy_to_user(to, from, n);
	return n;
}

extern long __copy_from_user_asm(void *to, long n, const void __user *from);

/**
 * __copy_from_user: - Copy a block of data from user space, with less checking.
 * @to:   Destination address, in kernel space.
 * @from: Source address, in user space.
 * @n:    Number of bytes to copy.
 *
 * Context: User context only.  This function may sleep.
 *
 * Copy data from user space to kernel space.  Caller must check
 * the specified block with access_ok() before calling this function.
 *
 * Returns number of bytes that could not be copied.
 * On success, this will be zero.
 *
 * If some data could not be copied, this function will pad the copied
 * data to the requested size using zero bytes.
 */
static inline unsigned long
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
	return __copy_from_user_asm(to, n, from);
}

/**
 * copy_from_user: - Copy a block of data from user space.
 * @to:   Destination address, in kernel space.
 * @from: Source address, in user space.
 * @n:    Number of bytes to copy.
 *
 * Context: User context only.  This function may sleep.
 *
 * Copy data from user space to kernel space.
 *
 * Returns number of bytes that could not be copied.
 * On success, this will be zero.
 *
 * If some data could not be copied, this function will pad the copied
 * data to the requested size using zero bytes.
 */
static inline unsigned long
copy_from_user(void *to, const void __user *from, unsigned long n)
{
	might_sleep();
	if (access_ok(VERIFY_READ, from, n))
		n = __copy_from_user(to, from, n);
	else
		memset(to, 0, n);
	return n;
}

extern unsigned long __copy_in_user_asm(const void __user *from, long n,
							void __user *to);

static inline unsigned long
__copy_in_user(void __user *to, const void __user *from, unsigned long n)
{
	return __copy_in_user_asm(from, n, to);
}

static inline unsigned long
copy_in_user(void __user *to, const void __user *from, unsigned long n)
{
	might_sleep();
	if (__access_ok(from,n) && __access_ok(to,n))
		n = __copy_in_user_asm(from, n, to);
	return n;
}

/*
 * Copy a null terminated string from userspace.
 */
extern long __strncpy_from_user_asm(long count, char *dst,
					const char __user *src);

static inline long
strncpy_from_user(char *dst, const char __user *src, long count)
{
        long res = -EFAULT;
        might_sleep();
        if (access_ok(VERIFY_READ, src, 1))
                res = __strncpy_from_user_asm(count, dst, src);
        return res;
}


extern long __strnlen_user_asm(long count, const char __user *src);

static inline unsigned long
strnlen_user(const char __user * src, unsigned long n)
{
	might_sleep();
	return __strnlen_user_asm(n, src);
}

/**
 * strlen_user: - Get the size of a string in user space.
 * @str: The string to measure.
 *
 * Context: User context only.  This function may sleep.
 *
 * Get the size of a NUL-terminated string in user space.
 *
 * Returns the size of the string INCLUDING the terminating NUL.
 * On exception, returns 0.
 *
 * If there is a limit on the length of a valid string, you may wish to
 * consider using strnlen_user() instead.
 */
#define strlen_user(str) strnlen_user(str, ~0UL)

/*
 * Zero Userspace
 */

extern long __clear_user_asm(void __user *to, long n);

static inline unsigned long
__clear_user(void __user *to, unsigned long n)
{
	return __clear_user_asm(to, n);
}

static inline unsigned long
clear_user(void __user *to, unsigned long n)
{
	might_sleep();
	if (access_ok(VERIFY_WRITE, to, n))
		n = __clear_user_asm(to, n);
	return n;
}

#endif /* __S390_UACCESS_H */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* include/asm-s390/uaccess.h
	3	*
	4	* S390 version
	5	* Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
	6	* Author(s): Hartmut Penner (hp@de.ibm.com),
	7	* Martin Schwidefsky (schwidefsky@de.ibm.com)
	8	*
	9	* Derived from "include/asm-i386/uaccess.h"
	10	*/
	11	#ifndef __S390_UACCESS_H
	12	#define __S390_UACCESS_H
	13
	14	/*
	15	* User space memory access functions
	16	*/
	17	#include <linux/sched.h>
	18	#include <linux/errno.h>
	19
	20	#define VERIFY_READ 0
	21	#define VERIFY_WRITE 1
	22
	23
	24	/*
	25	* The fs value determines whether argument validity checking should be
	26	* performed or not. If get_fs() == USER_DS, checking is performed, with
	27	* get_fs() == KERNEL_DS, checking is bypassed.
	28	*
	29	* For historical reasons, these macros are grossly misnamed.
	30	*/
	31
	32	#define MAKE_MM_SEG(a) ((mm_segment_t) { (a) })
	33
	34
	35	#define KERNEL_DS MAKE_MM_SEG(0)
	36	#define USER_DS MAKE_MM_SEG(1)
	37
	38	#define get_ds() (KERNEL_DS)
	39	#define get_fs() (current->thread.mm_segment)
	40
	41	#ifdef __s390x__
	42	#define set_fs(x) \
	43	({ \
	44	unsigned long __pto; \
	45	current->thread.mm_segment = (x); \
	46	__pto = current->thread.mm_segment.ar4 ? \
	47	S390_lowcore.user_asce : S390_lowcore.kernel_asce; \
	48	asm volatile ("lctlg 7,7,%0" : : "m" (__pto) ); \
	49	})
	50	#else
	51	#define set_fs(x) \
	52	({ \
	53	unsigned long __pto; \
	54	current->thread.mm_segment = (x); \
	55	__pto = current->thread.mm_segment.ar4 ? \
	56	S390_lowcore.user_asce : S390_lowcore.kernel_asce; \
	57	asm volatile ("lctl 7,7,%0" : : "m" (__pto) ); \
	58	})
	59	#endif
	60
	61	#define segment_eq(a,b) ((a).ar4 == (b).ar4)
	62
	63
	64	#define __access_ok(addr,size) (1)
65
66	#define access_ok(type,addr,size) __access_ok(addr,size)
67
1da177e4 LT	68	/*
	69	* The exception table consists of pairs of addresses: the first is the
	70	* address of an instruction that is allowed to fault, and the second is
	71	* the address at which the program should continue. No registers are
	72	* modified, so it is entirely up to the continuation code to figure out
	73	* what to do.
	74	*
	75	* All the routines below use bits of fixup code that are out of line
	76	* with the main instruction path. This means when everything is well,
	77	* we don't even have to jump over them. Further, they do not intrude
	78	* on our cache or tlb entries.
	79	*/
	80
	81	struct exception_table_entry
	82	{
	83	unsigned long insn, fixup;
	84	};
	85
	86	#ifndef __s390x__
	87	#define __uaccess_fixup \
	88	".section .fixup,\"ax\"\n" \
	89	"2: lhi %0,%4\n" \
	90	" bras 1,3f\n" \
	91	" .long 1b\n" \
	92	"3: l 1,0(1)\n" \
	93	" br 1\n" \
	94	".previous\n" \
	95	".section __ex_table,\"a\"\n" \
	96	" .align 4\n" \
	97	" .long 0b,2b\n" \
	98	".previous"
	99	#define __uaccess_clobber "cc", "1"
	100	#else /* __s390x__ */
	101	#define __uaccess_fixup \
	102	".section .fixup,\"ax\"\n" \
	103	"2: lghi %0,%4\n" \
	104	" jg 1b\n" \
	105	".previous\n" \
	106	".section __ex_table,\"a\"\n" \
	107	" .align 8\n" \
	108	" .quad 0b,2b\n" \
	109	".previous"
	110	#define __uaccess_clobber "cc"
	111	#endif /* __s390x__ */
	112
	113	/*
	114	* These are the main single-value transfer routines. They automatically
	115	* use the right size if we just have the right pointer type.
	116	*/
	117	#if __GNUC__ > 3 \|\| (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
	118	#define __put_user_asm(x, ptr, err) \
	119	({ \
	120	err = 0; \
	121	asm volatile( \
	122	"0: mvcs 0(%1,%2),%3,%0\n" \
	123	"1:\n" \
	124	__uaccess_fixup \
	125	: "+&d" (err) \
	126	: "d" (sizeof(*(ptr))), "a" (ptr), "Q" (x), \
	127	"K" (-EFAULT) \
	128	: __uaccess_clobber ); \
	129	})
	130	#else
	131	#define __put_user_asm(x, ptr, err) \
132	({ \
133	err = 0; \
134	asm volatile( \
135	"0: mvcs 0(%1,%2),0(%3),%0\n" \
136	"1:\n" \
137	__uaccess_fixup \
138	: "+&d" (err) \
139	: "d" (sizeof(*(ptr))), "a" (ptr), "a" (&(x)), \
140	"K" (-EFAULT), "m" (x) \
141	: __uaccess_clobber ); \
142	})
143	#endif
144
1da177e4 LT	145	#define __put_user(x, ptr) \
	146	({ \
	147	__typeof__(*(ptr)) __x = (x); \
	148	int __pu_err; \
17566c3c	149	__chk_user_ptr(ptr); \
1da177e4 LT	150	switch (sizeof (*(ptr))) { \
	151	case 1: \
	152	case 2: \
	153	case 4: \
	154	case 8: \
	155	__put_user_asm(__x, ptr, __pu_err); \
	156	break; \
	157	default: \
	158	__put_user_bad(); \
	159	break; \
	160	} \
	161	__pu_err; \
	162	})
1da177e4 LT	163
	164	#define put_user(x, ptr) \
	165	({ \
	166	might_sleep(); \
	167	__put_user(x, ptr); \
	168	})
	169
	170
	171	extern int __put_user_bad(void) __attribute__((noreturn));
	172
	173	#if __GNUC__ > 3 \|\| (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
	174	#define __get_user_asm(x, ptr, err) \
	175	({ \
	176	err = 0; \
	177	asm volatile ( \
	178	"0: mvcp %O1(%2,%R1),0(%3),%0\n" \
	179	"1:\n" \
	180	__uaccess_fixup \
	181	: "+&d" (err), "=Q" (x) \
	182	: "d" (sizeof(*(ptr))), "a" (ptr), \
	183	"K" (-EFAULT) \
	184	: __uaccess_clobber ); \
	185	})
	186	#else
	187	#define __get_user_asm(x, ptr, err) \
	188	({ \
	189	err = 0; \
	190	asm volatile ( \
	191	"0: mvcp 0(%2,%5),0(%3),%0\n" \
	192	"1:\n" \
	193	__uaccess_fixup \
	194	: "+&d" (err), "=m" (x) \
	195	: "d" (sizeof(*(ptr))), "a" (ptr), \
	196	"K" (-EFAULT), "a" (&(x)) \
	197	: __uaccess_clobber ); \
	198	})
	199	#endif
	200
1da177e4 LT	201	#define __get_user(x, ptr) \
	202	({ \
	203	__typeof__(*(ptr)) __x; \
	204	int __gu_err; \
17566c3c	205	__chk_user_ptr(ptr); \
1da177e4 LT	206	switch (sizeof(*(ptr))) { \
	207	case 1: \
	208	case 2: \
	209	case 4: \
	210	case 8: \
	211	__get_user_asm(__x, ptr, __gu_err); \
	212	break; \
	213	default: \
	214	__get_user_bad(); \
	215	break; \
	216	} \
	217	(x) = __x; \
	218	__gu_err; \
	219	})
1da177e4 LT	220
	221	#define get_user(x, ptr) \
	222	({ \
	223	might_sleep(); \
	224	__get_user(x, ptr); \
	225	})
	226
	227	extern int __get_user_bad(void) __attribute__((noreturn));
	228
	229	#define __put_user_unaligned __put_user
	230	#define __get_user_unaligned __get_user
	231
	232	extern long __copy_to_user_asm(const void from, long n, void __user to);
	233
	234	/**
	235	* __copy_to_user: - Copy a block of data into user space, with less checking.
	236	* @to: Destination address, in user space.
	237	* @from: Source address, in kernel space.
	238	* @n: Number of bytes to copy.
	239	*
	240	* Context: User context only. This function may sleep.
	241	*
	242	* Copy data from kernel space to user space. Caller must check
	243	* the specified block with access_ok() before calling this function.
	244	*
	245	* Returns number of bytes that could not be copied.
	246	* On success, this will be zero.
	247	*/
	248	static inline unsigned long
	249	__copy_to_user(void __user to, const void from, unsigned long n)
	250	{
	251	return __copy_to_user_asm(from, n, to);
	252	}
	253
	254	#define __copy_to_user_inatomic __copy_to_user
	255	#define __copy_from_user_inatomic __copy_from_user
	256
	257	/**
	258	* copy_to_user: - Copy a block of data into user space.
	259	* @to: Destination address, in user space.
	260	* @from: Source address, in kernel space.
	261	* @n: Number of bytes to copy.
	262	*
	263	* Context: User context only. This function may sleep.
	264	*
	265	* Copy data from kernel space to user space.
	266	*
	267	* Returns number of bytes that could not be copied.
	268	* On success, this will be zero.
	269	*/
	270	static inline unsigned long
	271	copy_to_user(void __user to, const void from, unsigned long n)
	272	{
	273	might_sleep();
	274	if (access_ok(VERIFY_WRITE, to, n))
	275	n = __copy_to_user(to, from, n);
	276	return n;
	277	}
	278
	279	extern long __copy_from_user_asm(void to, long n, const void __user from);
	280
	281	/**
	282	* __copy_from_user: - Copy a block of data from user space, with less checking.
	283	* @to: Destination address, in kernel space.
284	* @from: Source address, in user space.
285	* @n: Number of bytes to copy.
286	*
287	* Context: User context only. This function may sleep.
288	*
289	* Copy data from user space to kernel space. Caller must check
290	* the specified block with access_ok() before calling this function.
291	*
292	* Returns number of bytes that could not be copied.
293	* On success, this will be zero.
294	*
295	* If some data could not be copied, this function will pad the copied
296	* data to the requested size using zero bytes.
297	*/
298	static inline unsigned long
299	__copy_from_user(void to, const void __user from, unsigned long n)
300	{
301	return __copy_from_user_asm(to, n, from);
302	}
303
304	/**
305	* copy_from_user: - Copy a block of data from user space.
306	* @to: Destination address, in kernel space.
307	* @from: Source address, in user space.
308	* @n: Number of bytes to copy.
309	*
310	* Context: User context only. This function may sleep.
311	*
312	* Copy data from user space to kernel space.
313	*
314	* Returns number of bytes that could not be copied.
315	* On success, this will be zero.
316	*
317	* If some data could not be copied, this function will pad the copied
318	* data to the requested size using zero bytes.
319	*/
320	static inline unsigned long
321	copy_from_user(void to, const void __user from, unsigned long n)
322	{
323	might_sleep();
324	if (access_ok(VERIFY_READ, from, n))
325	n = __copy_from_user(to, from, n);
326	else
327	memset(to, 0, n);
328	return n;
329	}
330
331	extern unsigned long __copy_in_user_asm(const void __user *from, long n,
332	void __user *to);
333
334	static inline unsigned long
335	__copy_in_user(void __user to, const void __user from, unsigned long n)
336	{
337	return __copy_in_user_asm(from, n, to);
338	}
339
340	static inline unsigned long
341	copy_in_user(void __user to, const void __user from, unsigned long n)
342	{
343	might_sleep();
344	if (__access_ok(from,n) && __access_ok(to,n))
345	n = __copy_in_user_asm(from, n, to);
346	return n;
347	}
348
349	/*
350	* Copy a null terminated string from userspace.
351	*/
352	extern long __strncpy_from_user_asm(long count, char *dst,
353	const char __user *src);
354
355	static inline long
356	strncpy_from_user(char dst, const char __user src, long count)
357	{
358	long res = -EFAULT;
359	might_sleep();
360	if (access_ok(VERIFY_READ, src, 1))
361	res = __strncpy_from_user_asm(count, dst, src);
362	return res;
363	}
364
365
366	extern long __strnlen_user_asm(long count, const char __user *src);
367
368	static inline unsigned long
369	strnlen_user(const char __user * src, unsigned long n)
370	{
371	might_sleep();
372	return __strnlen_user_asm(n, src);
373	}
374
375	/**
376	* strlen_user: - Get the size of a string in user space.
377	* @str: The string to measure.
378	*
379	* Context: User context only. This function may sleep.
380	*
381	* Get the size of a NUL-terminated string in user space.
382	*
383	* Returns the size of the string INCLUDING the terminating NUL.
384	* On exception, returns 0.
385	*
386	* If there is a limit on the length of a valid string, you may wish to
387	* consider using strnlen_user() instead.
388	*/
389	#define strlen_user(str) strnlen_user(str, ~0UL)
390
391	/*
392	* Zero Userspace
393	*/
394
395	extern long __clear_user_asm(void __user *to, long n);
396
397	static inline unsigned long
398	__clear_user(void __user *to, unsigned long n)
399	{
400	return __clear_user_asm(to, n);
401	}
402
403	static inline unsigned long
404	clear_user(void __user *to, unsigned long n)
405	{
406	might_sleep();
407	if (access_ok(VERIFY_WRITE, to, n))
408	n = __clear_user_asm(to, n);
409	return n;
410	}
411
412	#endif /* __S390_UACCESS_H */