uaccess.h

Go to the documentation of this file.

/*
 *  S390 version
 *    Copyright IBM Corp. 1999, 2000
 *    Author(s): Hartmut Penner ([email protected]),
 *               Martin Schwidefsky ([email protected])
 *
 *  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>
#include <asm/ctl_reg.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)

#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;  \
    __ctl_load(__pto, 7, 7);                    \
})

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

static inline int __range_ok(unsigned long addr, unsigned long size)
{
    return 1;
}

#define __access_ok(addr, size)             \
({                          \
    __chk_user_ptr(addr);               \
    __range_ok((unsigned long)(addr), (size));  \
})

#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
{
    int insn, fixup;
};

static inline unsigned long extable_insn(const struct exception_table_entry *x)
{
    return (unsigned long)&x->insn + x->insn;
}

static inline unsigned long extable_fixup(const struct exception_table_entry *x)
{
    return (unsigned long)&x->fixup + x->fixup;
}

#define ARCH_HAS_SORT_EXTABLE
#define ARCH_HAS_SEARCH_EXTABLE

struct uaccess_ops {
    size_t (*copy_from_user)(size_t, const void __user *, void *);
    size_t (*copy_from_user_small)(size_t, const void __user *, void *);
    size_t (*copy_to_user)(size_t, void __user *, const void *);
    size_t (*copy_to_user_small)(size_t, void __user *, const void *);
    size_t (*copy_in_user)(size_t, void __user *, const void __user *);
    size_t (*clear_user)(size_t, void __user *);
    size_t (*strnlen_user)(size_t, const char __user *);
    size_t (*strncpy_from_user)(size_t, const char __user *, char *);
    int (*futex_atomic_op)(int op, u32 __user *, int oparg, int *old);
    int (*futex_atomic_cmpxchg)(u32 *, u32 __user *, u32 old, u32 new);
};

extern struct uaccess_ops uaccess;
extern struct uaccess_ops uaccess_std;
extern struct uaccess_ops uaccess_mvcos;
extern struct uaccess_ops uaccess_mvcos_switch;
extern struct uaccess_ops uaccess_pt;

extern int __handle_fault(unsigned long, unsigned long, int);

static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
{
    size = uaccess.copy_to_user_small(size, ptr, x);
    return size ? -EFAULT : size;
}

static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
{
    size = uaccess.copy_from_user_small(size, ptr, x);
    return size ? -EFAULT : size;
}

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 */
#define __put_user(x, ptr) \
({                              \
    __typeof__(*(ptr)) __x = (x);               \
    int __pu_err = -EFAULT;                 \
        __chk_user_ptr(ptr);                                    \
    switch (sizeof (*(ptr))) {              \
    case 1:                         \
    case 2:                         \
    case 4:                         \
    case 8:                         \
        __pu_err = __put_user_fn(sizeof (*(ptr)),   \
                     ptr, &__x);        \
        break;                      \
    default:                        \
        __put_user_bad();               \
        break;                      \
     }                          \
    __pu_err;                       \
})

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


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

#define __get_user(x, ptr)                  \
({                              \
    int __gu_err = -EFAULT;                 \
    __chk_user_ptr(ptr);                    \
    switch (sizeof(*(ptr))) {               \
    case 1: {                       \
        unsigned char __x;              \
        __gu_err = __get_user_fn(sizeof (*(ptr)),   \
                     ptr, &__x);        \
        (x) = *(__force __typeof__(*(ptr)) *) &__x; \
        break;                      \
    };                          \
    case 2: {                       \
        unsigned short __x;             \
        __gu_err = __get_user_fn(sizeof (*(ptr)),   \
                     ptr, &__x);        \
        (x) = *(__force __typeof__(*(ptr)) *) &__x; \
        break;                      \
    };                          \
    case 4: {                       \
        unsigned int __x;               \
        __gu_err = __get_user_fn(sizeof (*(ptr)),   \
                     ptr, &__x);        \
        (x) = *(__force __typeof__(*(ptr)) *) &__x; \
        break;                      \
    };                          \
    case 8: {                       \
        unsigned long long __x;             \
        __gu_err = __get_user_fn(sizeof (*(ptr)),   \
                     ptr, &__x);        \
        (x) = *(__force __typeof__(*(ptr)) *) &__x; \
        break;                      \
    };                          \
    default:                        \
        __get_user_bad();               \
        break;                      \
    }                           \
    __gu_err;                       \
})

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

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

#define __put_user_unaligned __put_user
#define __get_user_unaligned __get_user

static inline unsigned long __must_check
__copy_to_user(void __user *to, const void *from, unsigned long n)
{
    if (__builtin_constant_p(n) && (n <= 256))
        return uaccess.copy_to_user_small(n, to, from);
    else
        return uaccess.copy_to_user(n, to, from);
}

#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user

static inline unsigned long __must_check
copy_to_user(void __user *to, const void *from, unsigned long n)
{
    might_fault();
    if (access_ok(VERIFY_WRITE, to, n))
        n = __copy_to_user(to, from, n);
    return n;
}

static inline unsigned long __must_check
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
    if (__builtin_constant_p(n) && (n <= 256))
        return uaccess.copy_from_user_small(n, from, to);
    else
        return uaccess.copy_from_user(n, from, to);
}

extern void copy_from_user_overflow(void)
#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
__compiletime_warning("copy_from_user() buffer size is not provably correct")
#endif
;

static inline unsigned long __must_check
copy_from_user(void *to, const void __user *from, unsigned long n)
{
    unsigned int sz = __compiletime_object_size(to);

    might_fault();
    if (unlikely(sz != -1 && sz < n)) {
        copy_from_user_overflow();
        return n;
    }
    if (access_ok(VERIFY_READ, from, n))
        n = __copy_from_user(to, from, n);
    else
        memset(to, 0, n);
    return n;
}

static inline unsigned long __must_check
__copy_in_user(void __user *to, const void __user *from, unsigned long n)
{
    return uaccess.copy_in_user(n, to, from);
}

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

/*
 * Copy a null terminated string from userspace.
 */
static inline long __must_check
strncpy_from_user(char *dst, const char __user *src, long count)
{
        long res = -EFAULT;
    might_fault();
        if (access_ok(VERIFY_READ, src, 1))
        res = uaccess.strncpy_from_user(count, src, dst);
        return res;
}

static inline unsigned long
strnlen_user(const char __user * src, unsigned long n)
{
    might_fault();
    return uaccess.strnlen_user(n, src);
}

#define strlen_user(str) strnlen_user(str, ~0UL)

/*
 * Zero Userspace
 */

static inline unsigned long __must_check
__clear_user(void __user *to, unsigned long n)
{
    return uaccess.clear_user(n, to);
}

static inline unsigned long __must_check
clear_user(void __user *to, unsigned long n)
{
    might_fault();
    if (access_ok(VERIFY_WRITE, to, n))
        n = uaccess.clear_user(n, to);
    return n;
}

extern int copy_to_user_real(void __user *dest, void *src, size_t count);
extern int copy_from_user_real(void *dest, void __user *src, size_t count);

#endif /* __S390_UACCESS_H */