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/*
* arch/s390/lib/uaccess.S
* __copy_{from|to}_user functions.
*
* s390
* Copyright (C) 2000,2002 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Authors(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* These functions have standard call interface
*/
#include <linux/errno.h>
#include <asm/lowcore.h>
#include <asm/asm-offsets.h>
.text
.align 4
.globl __copy_from_user_asm
# %r2 = to, %r3 = n, %r4 = from
__copy_from_user_asm:
slr %r0,%r0
0: mvcp 0(%r3,%r2),0(%r4),%r0
jnz 1f
slr %r2,%r2
br %r14
1: la %r2,256(%r2)
la %r4,256(%r4)
ahi %r3,-256
2: mvcp 0(%r3,%r2),0(%r4),%r0
jnz 1b
3: slr %r2,%r2
br %r14
4: lhi %r0,-4096
lr %r5,%r4
slr %r5,%r0
nr %r5,%r0 # %r5 = (%r4 + 4096) & -4096
slr %r5,%r4 # %r5 = #bytes to next user page boundary
clr %r3,%r5 # copy crosses next page boundary ?
jnh 6f # no, the current page faulted
# move with the reduced length which is < 256
5: mvcp 0(%r5,%r2),0(%r4),%r0
slr %r3,%r5
alr %r2,%r5
6: lgr %r5,%r3 # copy remaining size
ahi %r5,-1 # subtract 1 for xc loop
bras %r4,8f
xc 0(1,%2),0(%2)
7: xc 0(256,%2),0(%2)
la %r2,256(%r2)
8: ahji %r5,-256
jnm 7b
ex %r5,0(%r2)
9: lr %r2,%r3
br %r14
.section __ex_table,"a"
.long 0b,4b
.long 2b,4b
.long 5b,6b
.previous
.align 4
.text
.globl __copy_to_user_asm
# %r2 = from, %r3 = n, %r4 = to
__copy_to_user_asm:
slr %r0,%r0
0: mvcs 0(%r3,%r4),0(%r2),%r0
jnz 1f
slr %r2,%r2
br %r14
1: la %r2,256(%r2)
la %r4,256(%r4)
ahi %r3,-256
2: mvcs 0(%r3,%r4),0(%r2),%r0
jnz 1b
3: slr %r2,%r2
br %r14
4: lhi %r0,-4096
lr %r5,%r4
slr %r5,%r0
nr %r5,%r0 # %r5 = (%r4 + 4096) & -4096
slr %r5,%r4 # %r5 = #bytes to next user page boundary
clr %r3,%r5 # copy crosses next page boundary ?
jnh 6f # no, the current page faulted
# move with the reduced length which is < 256
5: mvcs 0(%r5,%r4),0(%r2),%r0
slr %r3,%r5
6: lr %r2,%r3
br %r14
.section __ex_table,"a"
.long 0b,4b
.long 2b,4b
.long 5b,6b
.previous
.align 4
.text
.globl __copy_in_user_asm
# %r2 = from, %r3 = n, %r4 = to
__copy_in_user_asm:
sacf 256
bras 1,1f
mvc 0(1,%r4),0(%r2)
0: mvc 0(256,%r4),0(%r2)
la %r2,256(%r2)
la %r4,256(%r4)
1: ahi %r3,-256
jnm 0b
2: ex %r3,0(%r1)
sacf 0
slr %r2,%r2
br 14
3: mvc 0(1,%r4),0(%r2)
la %r2,1(%r2)
la %r4,1(%r4)
ahi %r3,-1
jnm 3b
4: lr %r2,%r3
sacf 0
br %r14
.section __ex_table,"a"
.long 0b,3b
.long 2b,3b
.long 3b,4b
.previous
.align 4
.text
.globl __clear_user_asm
# %r2 = to, %r3 = n
__clear_user_asm:
bras %r5,0f
.long empty_zero_page
0: l %r5,0(%r5)
slr %r0,%r0
1: mvcs 0(%r3,%r2),0(%r5),%r0
jnz 2f
slr %r2,%r2
br %r14
2: la %r2,256(%r2)
ahi %r3,-256
3: mvcs 0(%r3,%r2),0(%r5),%r0
jnz 2b
4: slr %r2,%r2
br %r14
5: lhi %r0,-4096
lr %r4,%r2
slr %r4,%r0
nr %r4,%r0 # %r4 = (%r2 + 4096) & -4096
slr %r4,%r2 # %r4 = #bytes to next user page boundary
clr %r3,%r4 # clear crosses next page boundary ?
jnh 7f # no, the current page faulted
# clear with the reduced length which is < 256
6: mvcs 0(%r4,%r2),0(%r5),%r0
slr %r3,%r4
7: lr %r2,%r3
br %r14
.section __ex_table,"a"
.long 1b,5b
.long 3b,5b
.long 6b,7b
.previous
.align 4
.text
.globl __strncpy_from_user_asm
# %r2 = count, %r3 = dst, %r4 = src
__strncpy_from_user_asm:
lhi %r0,0
lr %r1,%r4
la %r4,0(%r4) # clear high order bit from %r4
la %r2,0(%r2,%r4) # %r2 points to first byte after string
sacf 256
0: srst %r2,%r1
jo 0b
sacf 0
lr %r1,%r2
jh 1f # \0 found in string ?
ahi %r1,1 # include \0 in copy
1: slr %r1,%r4 # %r1 = copy length (without \0)
slr %r2,%r4 # %r2 = return length (including \0)
2: mvcp 0(%r1,%r3),0(%r4),%r0
jnz 3f
br %r14
3: la %r3,256(%r3)
la %r4,256(%r4)
ahi %r1,-256
mvcp 0(%r1,%r3),0(%r4),%r0
jnz 3b
br %r14
4: sacf 0
lhi %r2,-EFAULT
br %r14
.section __ex_table,"a"
.long 0b,4b
.previous
.align 4
.text
.globl __strnlen_user_asm
# %r2 = count, %r3 = src
__strnlen_user_asm:
lhi %r0,0
lr %r1,%r3
la %r3,0(%r3) # clear high order bit from %r4
la %r2,0(%r2,%r3) # %r2 points to first byte after string
sacf 256
0: srst %r2,%r1
jo 0b
sacf 0
ahi %r2,1 # strnlen_user result includes the \0
# or return count+1 if \0 not found
slr %r2,%r3
br %r14
2: sacf 0
slr %r2,%r2 # return 0 on exception
br %r14
.section __ex_table,"a"
.long 0b,2b
.previous
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