arch/arm/lib/strncpy_from_user.S

   1 /*
   2  *  linux/arch/arm/lib/strncpy_from_user.S
   3  *
   4  *  Copyright (C) 1995-2000 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/linkage.h>
  11 #include <asm/assembler.h>
  12 #include <asm/errno.h>
  13
  14         .text
  15         .align  5
  16
  17 /*
  18  * Copy a string from user space to kernel space.
  19  *  r0 = dst, r1 = src, r2 = byte length
  20  * returns the number of characters copied (strlen of copied string),
  21  *  -EFAULT on exception, or "len" if we fill the whole buffer
  22  */
  23 ENTRY(__strncpy_from_user)
  24         mov     ip, r1
  25 1:      subs    r2, r2, #1
  26         ldrusr  r3, r1, 1, pl
  27         bmi     2f
  28         strb    r3, [r0], #1
  29         teq     r3, #0
  30         bne     1b
  31         sub     r1, r1, #1      @ take NUL character out of count
  32 2:      sub     r0, r1, ip
  33         mov     pc, lr
  34 ENDPROC(__strncpy_from_user)
  35
  36         .pushsection .fixup,"ax"
  37         .align  0
  38 9001:   mov     r3, #0
  39         strb    r3, [r0, #0]    @ null terminate
  40         mov     r0, #-EFAULT
  41         mov     pc, lr
  42         .popsection
  43