/* 

 * User address space access functions.

 *

 * Copyright 1997 Andi Kleen <ak@muc.de>

 * Copyright 1997 Linus Torvalds

 * Copyright 2002 Andi Kleen <ak@suse.de>

 */

#include <xen/lib.h>

#include <xen/sched.h>

#include <asm/uaccess.h>

unsigned __copy_to_user_ll(void __user *to, const void *from, unsigned n)

{

    unsigned dummy;

    stac();

    asm volatile (

        "    cmp  $"STR(2*BYTES_PER_LONG-1)", %[cnt]\n"

        "    jbe  1f\n"

        "    mov  %k[to], %[cnt]\n"

        "    neg  %[cnt]\n"

        "    and  $"STR(BYTES_PER_LONG-1)", %[cnt]\n"

        "    sub  %[cnt], %[aux]\n"

        "4:  rep movsb\n" /* make 'to' address aligned */

        "    mov  %[aux], %[cnt]\n"

        "    shr  $"STR(LONG_BYTEORDER)", %[cnt]\n"

        "    and  $"STR(BYTES_PER_LONG-1)", %[aux]\n"

        "    .align 2,0x90\n"

        "0:  rep movs"__OS"\n" /* as many words as possible... */

        "    mov  %[aux],%[cnt]\n"

        "1:  rep movsb\n" /* ...remainder copied as bytes */

        "2:\n"

        ".section .fixup,\"ax\"\n"

        "5:  add %[aux], %[cnt]\n"

        "    jmp 2b\n"

        "3:  lea (%q[aux], %q[cnt], "STR(BYTES_PER_LONG)"), %[cnt]\n"

        "    jmp 2b\n"

        ".previous\n"

        _ASM_EXTABLE(4b, 5b)

        _ASM_EXTABLE(0b, 3b)

        _ASM_EXTABLE(1b, 2b)

        : [cnt] "+c" (n), [to] "+D" (to), [from] "+S" (from),

          [aux] "=&r" (dummy)

        : "[aux]" (n)

        : "memory" );

    clac();

    return n;

}

unsigned __copy_from_user_ll(void *to, const void __user *from, unsigned n)

{

    unsigned dummy;

    stac();

    asm volatile (

        "    cmp  $"STR(2*BYTES_PER_LONG-1)", %[cnt]\n"

        "    jbe  1f\n"

        "    mov  %k[to], %[cnt]\n"

        "    neg  %[cnt]\n"

        "    and  $"STR(BYTES_PER_LONG-1)", %[cnt]\n"

        "    sub  %[cnt], %[aux]\n"

        "4:  rep movsb\n" /* make 'to' address aligned */

        "    mov  %[aux],%[cnt]\n"

        "    shr  $"STR(LONG_BYTEORDER)", %[cnt]\n"

        "    and  $"STR(BYTES_PER_LONG-1)", %[aux]\n"

        "    .align 2,0x90\n"

        "0:  rep movs"__OS"\n" /* as many words as possible... */

        "    mov  %[aux], %[cnt]\n"

        "1:  rep movsb\n" /* ...remainder copied as bytes */

        "2:\n"

        ".section .fixup,\"ax\"\n"

        "5:  add  %[aux], %[cnt]\n"

        "    jmp 6f\n"

        "3:  lea  (%q[aux], %q[cnt], "STR(BYTES_PER_LONG)"), %[cnt]\n"

        "6:  mov  %[cnt], %k[from]\n"

        "    xchg %%eax, %[aux]\n"

        "    xor  %%eax, %%eax\n"

        "    rep stosb\n"

        "    xchg %[aux], %%eax\n"

        "    mov  %k[from], %[cnt]\n"

        "    jmp 2b\n"

        ".previous\n"

        _ASM_EXTABLE(4b, 5b)

        _ASM_EXTABLE(0b, 3b)

        _ASM_EXTABLE(1b, 6b)

        : [cnt] "+c" (n), [to] "+D" (to), [from] "+S" (from),

          [aux] "=&r" (dummy)

        : "[aux]" (n)

        : "memory" );

    clac();

    return n;

}

/**

 * 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.

 */

unsigned copy_to_user(void __user *to, const void *from, unsigned n)

{

    if ( access_ok(to, n) )

        n = __copy_to_user(to, from, n);

    return n;

}

/**

 * clear_user: - Zero a block of memory in user space.

 * @to:   Destination address, in user space.

 * @n:    Number of bytes to zero.

 *

 * Zero a block of memory in user space.

 *

 * Returns number of bytes that could not be cleared.

 * On success, this will be zero.

 */

unsigned clear_user(void __user *to, unsigned n)

{

    if ( access_ok(to, n) )

    {

        stac();

        asm volatile (

            "0:  rep stos"__OS"\n"

            "    mov  %[bytes], %[cnt]\n"

            "1:  rep stosb\n"

            "2:\n"

            ".section .fixup,\"ax\"\n"

            "3:  lea  (%q[bytes], %q[longs], "STR(BYTES_PER_LONG)"), %[cnt]\n"

            "    jmp  2b\n"

            ".previous\n"

            _ASM_EXTABLE(0b,3b)

            _ASM_EXTABLE(1b,2b)

            : [cnt] "=&c" (n), [to] "+D" (to)

            : [bytes] "r" (n & (BYTES_PER_LONG - 1)),

              [longs] "0" (n / BYTES_PER_LONG), "a" (0) );

        clac();

    }

    return n;

}

/**

 * 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.

 */

unsigned copy_from_user(void *to, const void __user *from, unsigned n)

{

    if ( access_ok(from, n) )

        n = __copy_from_user(to, from, n);

    else

        memset(to, 0, n);

    return n;

}

/*

 * Local variables:

 * mode: C

 * c-file-style: "BSD"

 * c-basic-offset: 4

 * tab-width: 4

 * indent-tabs-mode: nil

 * End:

 */