arch/unicore32/lib/strncpy_from_user.S

   1 /*
   2  * linux/arch/unicore32/lib/strncpy_from_user.S
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  * Copyright (C) 2001-2010 GUAN Xue-tao
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/linkage.h>
  13 #include <asm/assembler.h>
  14 #include <asm/errno.h>
  15
  16         .text
  17         .align  5
  18
  19 /*
  20  * Copy a string from user space to kernel space.
  21  *  r0 = dst, r1 = src, r2 = byte length
  22  * returns the number of characters copied (strlen of copied string),
  23  *  -EFAULT on exception, or "len" if we fill the whole buffer
  24  */
  25 ENTRY(__strncpy_from_user)
  26         mov     ip, r1
  27 1:      sub.a   r2, r2, #1
  28         ldrusr  r3, r1, 1, ns
  29         bfs     2f
  30         stb.w   r3, [r0]+, #1
  31         cxor.a  r3, #0
  32         bne     1b
  33         sub     r1, r1, #1      @ take NUL character out of count
  34 2:      sub     r0, r1, ip
  35         mov     pc, lr
  36 ENDPROC(__strncpy_from_user)
  37
  38         .pushsection .fixup,"ax"
  39         .align  0
  40 9001:   mov     r3, #0
  41         stb     r3, [r0+], #0   @ null terminate
  42         mov     r0, #-EFAULT
  43         mov     pc, lr
  44         .popsection
  45