uaccess.h

讲述linux的初始化过程

})

#define __get_user_asm_1(x, ptr, err)                                   \
({                                                                      \
        __asm__ __volatile__ (  "   iac   1\n"                          \
                                "   sr    %1,%1\n"                      \
                                "   la    4,%2\n"                       \
                                "   sr    %0,%0\n"                      \
                                "   sacf  512\n"                        \
                                "0: ic    %0,0(4)\n"                    \
                                "   sacf  0(1)\n"                       \
                                "1:\n"                                  \
                                ".section .fixup,\"ax\"\n"              \
                                "2: sacf  0(1)\n"                       \
                                "   lhi   %1,%h3\n"                     \
                                "   bras  4,3f\n"                       \
                                "   .long 1b\n"                         \
                                "3: l     4,0(4)\n"                     \
                                "   br    4\n"                          \
                                ".previous\n"                           \
                                ".section __ex_table,\"a\"\n"           \
                                "   .align 4\n"                         \
                                "   .long 0b,2b\n"                      \
                                ".previous"                             \
                                : "=d" (x) , "=&d" (err)                \
                                : "m" (*(__u8*) ptr), "K" (-EFAULT)     \
                                : "1", "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;                                  \
                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__(x) __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 inline unsigned long
__copy_to_user_asm(void* to, const void* from,  long n)
{

        __asm__ __volatile__ (  "   iac   1\n"
                                "   lr    2,%2\n"
                                "   lr    4,%1\n"
                                "   lr    3,%0\n"
                                "   lr    5,3\n"
                                "   sacf  512\n"
                                "0: mvcle 4,2,0\n"
                                "   jo    0b\n"
                                "1: sacf  0(1)\n"
                                "   lr    %0,3\n"
				".section __ex_table,\"a\"\n"
				"   .align 4\n"
				"   .long  0b,1b\n"
				".previous"
                                : "+&d" (n) : "d" (to), "d" (from)
                                : "1", "2", "3", "4", "5" );
        return n;
}

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

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

extern inline unsigned long
__copy_from_user_asm(void* to, const void* from,  long n)
{
        __asm__ __volatile__ (  "   iac   1\n"
				"   lr    2,%1\n"
                                "   lr    4,%2\n"
                                "   lr    3,%0\n"
                                "   lr    5,3\n"
                                "   sacf  512\n"
                                "0: mvcle 2,4,0\n"
                                "   jo    0b\n"
                                "1: sacf  0(1)\n"
                                "   lr    %0,3\n"
				".section __ex_table,\"a\"\n"
				"   .align 4\n"
				"   .long  0b,1b\n"
				".previous"
                                : "+&d" (n) : "d" (to), "d" (from)
                                : "1", "2", "3", "4", "5" );
        return n;
}


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

#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,from,__n);        \
        }                                                       \
        else                                                    \
                err = __n;                                      \
        err;                                                    \
})

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

static inline long
strncpy_from_user(char *dst, const char *src, long count)
{
        int len;
        __asm__ __volatile__ (  "   iac   1\n"
				"   slr   %0,%0\n"
				"   lr    2,%1\n"
                                "   lr    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"
                                "   ahi   %0,1\n"
                                "   clr   %0,%3\n"
                                "   jl    0b\n"
                                "2: sacf  0(1)\n"
				".section .fixup,\"ax\"\n"
                                "3: lhi   %0,%h4\n"
				"   basr  3,0\n"
                                "   l     3,4f-.(3)\n"
                                "   br    3\n"
				"4: .long 2b\n"
				".previous\n"
				".section __ex_table,\"a\"\n"
				"   .align 4\n"
				"   .long  0b,3b\n"
                                "   .long  1b,3b\n"
				".previous"
                                : "=&a" (len)
                                : "a" (dst), "d" (src), "d" (count),
                                  "K" (-EFAULT)
                                : "1", "2", "3", "4", "memory" );
        return len;
}

/*
 * 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)
{
	__asm__ __volatile__ ("   iac   1\n"
                              "   alr   %0,%1\n"
			      "   slr   0,0\n"
			      "   lr    4,%1\n"
			      "   sacf  512\n"
			      "0: srst  %0,4\n"
			      "   jo    0b\n"
			      "   slr   %0,%1\n"
			      "   ahi   %0,1\n"
			      "   sacf  0(1)\n"
                              "1:\n"
                              ".section .fixup,\"ax\"\n"
                              "2: sacf  0(1)\n"
                              "   slr   %0,%0\n"
                              "   bras  4,3f\n"
                              "   .long 1b\n"
                              "3: l     4,0(4)\n"
                              "   br    4\n"
                              ".previous\n"
			      ".section __ex_table,\"a\"\n"
			      "   .align 4\n"
			      "   .long  0b,2b\n"
			      ".previous"
			      : "+&a" (n) : "d" (src)
			      : "cc", "0", "1", "4" );
        return n;
}
#define strlen_user(str) strnlen_user(str, ~0UL)

/*
 * Zero Userspace
 */

static inline unsigned long
clear_user(void *to, unsigned long n)
{
        __asm__ __volatile__ (  "   iac   1\n"
                                "   sacf  512\n"
                                "   lr    4,%1\n"
                                "   lr    5,%0\n"
                                "   sr    2,2\n"
                                "   sr    3,3\n"
                                "0: mvcle 4,2,0\n"
                                "   jo    0b\n"
                                "1: sacf  0(1)\n"
                                "   lr    %0,3\n"
				".section __ex_table,\"a\"\n"
				"   .align 4\n"
				"   .long  0b,1b\n"
				".previous"
                                : "+&a" (n)
                                : "a"   (to)
                                : "cc", "1", "2", "3", "4", "5" );
        return n;
}

#endif                                 /* _S390_UACCESS_H                  */