Linux v2.6.15-rc6

[pohmelfs.git] / include / asm-i386 / uaccess.h

#ifndef __i386_UACCESS_H
#define __i386_UACCESS_H

/*
 * User space memory access functions
 */
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/thread_info.h>
#include <linux/prefetch.h>
#include <linux/string.h>
#include <asm/page.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(s)  ((mm_segment_t) { (s) })


#define KERNEL_DS       MAKE_MM_SEG(0xFFFFFFFFUL)
#define USER_DS         MAKE_MM_SEG(PAGE_OFFSET)

#define get_ds()        (KERNEL_DS)
#define get_fs()        (current_thread_info()->addr_limit)
#define set_fs(x)       (current_thread_info()->addr_limit = (x))

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

/*
 * movsl can be slow when source and dest are not both 8-byte aligned
 */
#ifdef CONFIG_X86_INTEL_USERCOPY
extern struct movsl_mask {
        int mask;
} ____cacheline_aligned_in_smp movsl_mask;
#endif

#define __addr_ok(addr) ((unsigned long __force)(addr) < (current_thread_info()->addr_limit.seg))

/*
 * Test whether a block of memory is a valid user space address.
 * Returns 0 if the range is valid, nonzero otherwise.
 *
 * This is equivalent to the following test:
 * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
 *
 * This needs 33-bit arithmetic. We have a carry...
 */
#define __range_ok(addr,size) ({ \
        unsigned long flag,sum; \
        __chk_user_ptr(addr); \
        asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
                :"=&r" (flag), "=r" (sum) \
                :"1" (addr),"g" ((int)(size)),"g" (current_thread_info()->addr_limit.seg)); \
        flag; })

/**
 * access_ok: - Checks if a user space pointer is valid
 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
 *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
 *        to write to a block, it is always safe to read from it.
 * @addr: User space pointer to start of block to check
 * @size: Size of block to check
 *
 * Context: User context only.  This function may sleep.
 *
 * Checks if a pointer to a block of memory in user space is valid.
 *
 * Returns true (nonzero) if the memory block may be valid, false (zero)
 * if it is definitely invalid.
 *
 * Note that, depending on architecture, this function probably just
 * checks that the pointer is in the user space range - after calling
 * this function, memory access functions may still return -EFAULT.
 */
#define access_ok(type,addr,size) (likely(__range_ok(addr,size) == 0))

/*
 * 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;
};

extern int fixup_exception(struct pt_regs *regs);

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 *
 * This gets kind of ugly. We want to return _two_ values in "get_user()"
 * and yet we don't want to do any pointers, because that is too much
 * of a performance impact. Thus we have a few rather ugly macros here,
 * and hide all the ugliness from the user.
 *
 * The "__xxx" versions of the user access functions are versions that
 * do not verify the address space, that must have been done previously
 * with a separate "access_ok()" call (this is used when we do multiple
 * accesses to the same area of user memory).
 */

extern void __get_user_1(void);
extern void __get_user_2(void);
extern void __get_user_4(void);

#define __get_user_x(size,ret,x,ptr) \
        __asm__ __volatile__("call __get_user_" #size \
                :"=a" (ret),"=d" (x) \
                :"0" (ptr))


/* Careful: we have to cast the result to the type of the pointer for sign reasons */
/**
 * get_user: - Get a simple variable from user space.
 * @x:   Variable to store result.
 * @ptr: Source address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple variable from user space to kernel
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and the result of
 * dereferencing @ptr must be assignable to @x without a cast.
 *
 * Returns zero on success, or -EFAULT on error.
 * On error, the variable @x is set to zero.
 */
#define get_user(x,ptr)                                                 \
({      int __ret_gu;                                                   \
        unsigned long __val_gu;                                         \
        __chk_user_ptr(ptr);                                            \
        switch(sizeof (*(ptr))) {                                       \
        case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
        case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
        case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
        default: __get_user_x(X,__ret_gu,__val_gu,ptr); break;          \
        }                                                               \
        (x) = (__typeof__(*(ptr)))__val_gu;                             \
        __ret_gu;                                                       \
})

extern void __put_user_bad(void);

/*
 * Strange magic calling convention: pointer in %ecx,
 * value in %eax(:%edx), return value in %eax, no clobbers.
 */
extern void __put_user_1(void);
extern void __put_user_2(void);
extern void __put_user_4(void);
extern void __put_user_8(void);

#define __put_user_1(x, ptr) __asm__ __volatile__("call __put_user_1":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
#define __put_user_2(x, ptr) __asm__ __volatile__("call __put_user_2":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
#define __put_user_4(x, ptr) __asm__ __volatile__("call __put_user_4":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
#define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=a" (__ret_pu):"A" ((typeof(*(ptr)))(x)), "c" (ptr))
#define __put_user_X(x, ptr) __asm__ __volatile__("call __put_user_X":"=a" (__ret_pu):"c" (ptr))

/**
 * put_user: - Write a simple value into user space.
 * @x:   Value to copy to user space.
 * @ptr: Destination address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple value from kernel space to user
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 * to the result of dereferencing @ptr.
 *
 * Returns zero on success, or -EFAULT on error.
 */
#ifdef CONFIG_X86_WP_WORKS_OK

#define put_user(x,ptr)                                         \
({      int __ret_pu;                                           \
        __chk_user_ptr(ptr);                                    \
        switch(sizeof(*(ptr))) {                                \
        case 1: __put_user_1(x, ptr); break;                    \
        case 2: __put_user_2(x, ptr); break;                    \
        case 4: __put_user_4(x, ptr); break;                    \
        case 8: __put_user_8(x, ptr); break;                    \
        default:__put_user_X(x, ptr); break;                    \
        }                                                       \
        __ret_pu;                                               \
})

#else
#define put_user(x,ptr)                                         \
({                                                              \
        int __ret_pu;                                           \
        __typeof__(*(ptr)) __pus_tmp = x;                       \
        __ret_pu=0;                                             \
        if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp,          \
                                sizeof(*(ptr))) != 0))          \
                __ret_pu=-EFAULT;                               \
        __ret_pu;                                               \
 })


#endif

/**
 * __get_user: - Get a simple variable from user space, with less checking.
 * @x:   Variable to store result.
 * @ptr: Source address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple variable from user space to kernel
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and the result of
 * dereferencing @ptr must be assignable to @x without a cast.
 *
 * Caller must check the pointer with access_ok() before calling this
 * function.
 *
 * Returns zero on success, or -EFAULT on error.
 * On error, the variable @x is set to zero.
 */
#define __get_user(x,ptr) \
  __get_user_nocheck((x),(ptr),sizeof(*(ptr)))


/**
 * __put_user: - Write a simple value into user space, with less checking.
 * @x:   Value to copy to user space.
 * @ptr: Destination address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple value from kernel space to user
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 * to the result of dereferencing @ptr.
 *
 * Caller must check the pointer with access_ok() before calling this
 * function.
 *
 * Returns zero on success, or -EFAULT on error.
 */
#define __put_user(x,ptr) \
  __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))

#define __put_user_nocheck(x,ptr,size)                          \
({                                                              \
        long __pu_err;                                          \
        __put_user_size((x),(ptr),(size),__pu_err,-EFAULT);     \
        __pu_err;                                               \
})


#define __put_user_u64(x, addr, err)                            \
        __asm__ __volatile__(                                   \
                "1:     movl %%eax,0(%2)\n"                     \
                "2:     movl %%edx,4(%2)\n"                     \
                "3:\n"                                          \
                ".section .fixup,\"ax\"\n"                      \
                "4:     movl %3,%0\n"                           \
                "       jmp 3b\n"                               \
                ".previous\n"                                   \
                ".section __ex_table,\"a\"\n"                   \
                "       .align 4\n"                             \
                "       .long 1b,4b\n"                          \
                "       .long 2b,4b\n"                          \
                ".previous"                                     \
                : "=r"(err)                                     \
                : "A" (x), "r" (addr), "i"(-EFAULT), "0"(err))

#ifdef CONFIG_X86_WP_WORKS_OK

#define __put_user_size(x,ptr,size,retval,errret)                       \
do {                                                                    \
        retval = 0;                                                     \
        __chk_user_ptr(ptr);                                            \
        switch (size) {                                                 \
        case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break; \
        case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
        case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break; \
        case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
          default: __put_user_bad();                                    \
        }                                                               \
} while (0)

#else

#define __put_user_size(x,ptr,size,retval,errret)                       \
do {                                                                    \
        __typeof__(*(ptr)) __pus_tmp = x;                               \
        retval = 0;                                                     \
                                                                        \
        if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))     \
                retval = errret;                                        \
} while (0)

#endif
struct __large_struct { unsigned long buf[100]; };
#define __m(x) (*(struct __large_struct __user *)(x))

/*
 * Tell gcc we read from memory instead of writing: this is because
 * we do not write to any memory gcc knows about, so there are no
 * aliasing issues.
 */
#define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
        __asm__ __volatile__(                                           \
                "1:     mov"itype" %"rtype"1,%2\n"                      \
                "2:\n"                                                  \
                ".section .fixup,\"ax\"\n"                              \
                "3:     movl %3,%0\n"                                   \
                "       jmp 2b\n"                                       \
                ".previous\n"                                           \
                ".section __ex_table,\"a\"\n"                           \
                "       .align 4\n"                                     \
                "       .long 1b,3b\n"                                  \
                ".previous"                                             \
                : "=r"(err)                                             \
                : ltype (x), "m"(__m(addr)), "i"(errret), "0"(err))


#define __get_user_nocheck(x,ptr,size)                          \
({                                                              \
        long __gu_err;                                          \
        unsigned long __gu_val;                                 \
        __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
        (x) = (__typeof__(*(ptr)))__gu_val;                     \
        __gu_err;                                               \
})

extern long __get_user_bad(void);

#define __get_user_size(x,ptr,size,retval,errret)                       \
do {                                                                    \
        retval = 0;                                                     \
        __chk_user_ptr(ptr);                                            \
        switch (size) {                                                 \
        case 1: __get_user_asm(x,ptr,retval,"b","b","=q",errret);break; \
        case 2: __get_user_asm(x,ptr,retval,"w","w","=r",errret);break; \
        case 4: __get_user_asm(x,ptr,retval,"l","","=r",errret);break;  \
        default: (x) = __get_user_bad();                                \
        }                                                               \
} while (0)

#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
        __asm__ __volatile__(                                           \
                "1:     mov"itype" %2,%"rtype"1\n"                      \
                "2:\n"                                                  \
                ".section .fixup,\"ax\"\n"                              \
                "3:     movl %3,%0\n"                                   \
                "       xor"itype" %"rtype"1,%"rtype"1\n"               \
                "       jmp 2b\n"                                       \
                ".previous\n"                                           \
                ".section __ex_table,\"a\"\n"                           \
                "       .align 4\n"                                     \
                "       .long 1b,3b\n"                                  \
                ".previous"                                             \
                : "=r"(err), ltype (x)                                  \
                : "m"(__m(addr)), "i"(errret), "0"(err))


unsigned long __must_check __copy_to_user_ll(void __user *to,
                                const void *from, unsigned long n);
unsigned long __must_check __copy_from_user_ll(void *to,
                                const void __user *from, unsigned long n);

/*
 * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
 * we return the initial request size (1, 2 or 4), as copy_*_user should do.
 * If a store crosses a page boundary and gets a fault, the x86 will not write
 * anything, so this is accurate.
 */

/**
 * __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 __must_check
__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
{
        if (__builtin_constant_p(n)) {
                unsigned long ret;

                switch (n) {
                case 1:
                        __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
                        return ret;
                case 2:
                        __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
                        return ret;
                case 4:
                        __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
                        return ret;
                }
        }
        return __copy_to_user_ll(to, from, n);
}

static inline unsigned long __must_check
__copy_to_user(void __user *to, const void *from, unsigned long n)
{
       might_sleep();
       return __copy_to_user_inatomic(to, from, n);
}

/**
 * __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_inatomic(void *to, const void __user *from, unsigned long n)
{
        if (__builtin_constant_p(n)) {
                unsigned long ret;

                switch (n) {
                case 1:
                        __get_user_size(*(u8 *)to, from, 1, ret, 1);
                        return ret;
                case 2:
                        __get_user_size(*(u16 *)to, from, 2, ret, 2);
                        return ret;
                case 4:
                        __get_user_size(*(u32 *)to, from, 4, ret, 4);
                        return ret;
                }
        }
        return __copy_from_user_ll(to, from, n);
}

static inline unsigned long
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
       might_sleep();
       return __copy_from_user_inatomic(to, from, n);
}
unsigned long __must_check copy_to_user(void __user *to,
                                const void *from, unsigned long n);
unsigned long __must_check copy_from_user(void *to,
                                const void __user *from, unsigned long n);
long __must_check strncpy_from_user(char *dst, const char __user *src,
                                long count);
long __must_check __strncpy_from_user(char *dst,
                                const char __user *src, long count);

/**
 * 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 >> 1)

long strnlen_user(const char __user *str, long n);
unsigned long __must_check clear_user(void __user *mem, unsigned long len);
unsigned long __must_check __clear_user(void __user *mem, unsigned long len);

#endif /* __i386_UACCESS_H */