uaccess.h

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#define __get_user_asm_2(x, ptr, err)                                      \
({                                                                         \
        __asm__ __volatile__ (  "   sr    %1,%1\n"                         \
                                "   la    4,%2\n"                          \
                                "   sacf  512\n"                           \
                                "0: lh    %0,0(4)\n"                       \
                                "1: sacf  0\n"                             \
                                ".section .fixup,\"ax\"\n"                 \
                                "2: lhi   %1,%h3\n"                        \
                                "   jg    1b\n"                            \
                                ".previous\n"                              \
                                ".section __ex_table,\"a\"\n"              \
                                "   .align 8\n"                            \
                                "   .quad 0b,2b\n"                         \
                                ".previous"                                \
                                : "=d" (x) , "=&d" (err)                   \
                                : "m" (*(const __u16*)(ptr)),"K" (-EFAULT) \
                                : "cc", "4" );                             \
})

#define __get_user_asm_1(x, ptr, err)                                     \
({                                                                        \
        __asm__ __volatile__ (  "   sr    %1,%1\n"                        \
                                "   la    4,%2\n"                         \
                                "   sr    %0,%0\n"                        \
                                "   sacf  512\n"                          \
                                "0: ic    %0,0(4)\n"                      \
                                "1: sacf  0\n"                            \
                                ".section .fixup,\"ax\"\n"                \
                                "2: lhi   %1,%h3\n"                       \
                                "   jg    1b\n"                           \
                                ".previous\n"                             \
                                ".section __ex_table,\"a\"\n"             \
                                "   .align 8\n"                           \
                                "   .quad 0b,2b\n"                        \
                                ".previous"                               \
                                : "=d" (x) , "=&d" (err)                  \
                                : "m" (*(const __u8*)(ptr)),"K" (-EFAULT) \
                                : "cc", "4" );                            \
})

#define __get_user(x, ptr)                                      \
({                                                              \
        int __gu_err;                                           \
        switch (sizeof(*(ptr))) {                               \
                case 1:                                         \
                        __get_user_asm_1(x,ptr,__gu_err);       \
                        break;                                  \
                case 2:                                         \
                        __get_user_asm_2(x,ptr,__gu_err);       \
                        break;                                  \
                case 4:                                         \
                        __get_user_asm_4(x,ptr,__gu_err);       \
                        break;                                  \
                case 8:                                         \
                        __get_user_asm_8(x,ptr,__gu_err);       \
                        break;                                  \
                default:                                        \
                        (x) = 0;                                \
                        __gu_err = __get_user_bad();            \
                break;                                          \
        }                                                       \
        __gu_err;                                               \
})

#define get_user(x, ptr)                                        \
({                                                              \
        long __gu_err = -EFAULT;                                \
        __typeof__(ptr) __gu_addr = (ptr);                      \
        __typeof__(*(ptr)) __x;                                 \
        if (__access_ok((long)__gu_addr,sizeof(*(ptr)))) {      \
                __gu_err = 0;                                   \
                __get_user((__x), (__gu_addr));                 \
                (x) = __x;                                      \
        }                                                       \
        else                                                    \
                (x) = 0;                                        \
        __gu_err;                                               \
})

extern int __get_user_bad(void);

/*
 * access register are set up, that 4 points to secondary (user) , 2 to primary (kernel)
 */

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

#define __copy_to_user(to, from, n)                             \
({                                                              \
        __copy_to_user_asm(from, n, to);                        \
})

#define copy_to_user(to, from, n)                               \
({                                                              \
        long err = 0;                                           \
        __typeof__(n) __n = (n);                                \
        if (__access_ok(to,__n)) {                              \
                err = __copy_to_user_asm(from, __n, to);        \
        }                                                       \
        else                                                    \
                err = __n;                                      \
        err;                                                    \
})

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

#define __copy_from_user(to, from, n)                           \
({                                                              \
        __copy_from_user_asm(to, n, from);                      \
})

#define copy_from_user(to, from, n)                             \
({                                                              \
        long err = 0;                                           \
        __typeof__(n) __n = (n);                                \
        if (__access_ok(from,__n)) {                            \
                err = __copy_from_user_asm(to, __n, from);      \
        }                                                       \
        else                                                    \
                err = __n;                                      \
        err;                                                    \
})

/*
 * Copy a null terminated string from userspace.
 */

static inline long
__strncpy_from_user(char *dst, const char *src, long count)
{
        long len;
        __asm__ __volatile__ (  "   slgr  %0,%0\n"
				"   lgr   2,%1\n"
                                "   lgr   4,%2\n"
                                "   slr   3,3\n"
                                "   sacf  512\n"
                                "0: ic    3,0(%0,4)\n"
                                "1: stc   3,0(%0,2)\n"
                                "   ltr   3,3\n"
                                "   jz    2f\n"
                                "   aghi  %0,1\n"
                                "   cgr   %0,%3\n"
                                "   jl    0b\n"
                                "2: sacf  0\n"
				".section .fixup,\"ax\"\n"
				"3: lghi  %0,%h4\n"
				"   jg    2b\n"  
				".previous\n"
				".section __ex_table,\"a\"\n"
				"   .align 8\n"
				"   .quad  0b,3b\n"
				"   .quad  1b,3b\n"
				".previous"
                                : "=&a" (len)
                                : "a"  (dst), "d" (src), "d" (count),
                                  "K" (-EFAULT)
                                : "cc", "2" ,"3", "4" );
        return len;
}

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

/*
 * Return the size of a string (including the ending 0)
 *
 * Return 0 for error
 */
static inline unsigned long
strnlen_user(const char * src, unsigned long n)
{
#if 0
        __asm__ __volatile__ ("   algr  %0,%1\n"
                              "   slgr  0,0\n"
                              "   lgr   4,%1\n"
                              "   sacf  512\n"
                              "0: srst  %0,4\n"
                              "   jo    0b\n"
                              "   slgr  %0,%1\n"
                              "   aghi  %0,1\n"
                              "1: sacf  0\n"
                              ".section .fixup,\"ax\"\n"
                              "2: slgr  %0,%0\n"
                              "   jg    1b\n"
                              ".previous\n"
                              ".section __ex_table,\"a\"\n"
                              "   .align 8\n"
                              "   .quad  0b,2b\n"
                              ".previous"
                              : "+&a" (n) : "d" (src)
                              : "cc", "0", "4" );
#else
	__asm__ __volatile__ ("   lgr   4,%1\n"
			      "   sacf  512\n"
			      "0: cli   0(4),0x00\n"
                              "   la    4,1(4)\n"
			      "   je    1f\n"
                              "   brctg %0,0b\n"
			      "1: lgr   %0,4\n"
			      "   slgr  %0,%1\n"
			      "2: sacf  0\n"
                              ".section .fixup,\"ax\"\n"
                              "3: slgr  %0,%0\n"
                              "   jg    2b\n"  
                              ".previous\n"
			      ".section __ex_table,\"a\"\n"
			      "   .align 8\n"
			      "   .quad  0b,3b\n"
			      ".previous"
			      : "+&a" (n) : "d" (src)
			      : "cc", "4" );
#endif
        return n;
}
#define strlen_user(str) strnlen_user(str, ~0UL)

/*
 * Zero Userspace
 */

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

#define __clear_user(to, n)                                     \
({                                                              \
        __clear_user_asm(to, n);                                \
})

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

#endif                                 /* _S390_UACCESS_H                  */