root/arch/unicore32/lib/strncpy_from_user.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * linux/arch/unicore32/lib/strncpy_from_user.S
   4  *
   5  * Code specific to PKUnity SoC and UniCore ISA
   6  *
   7  * Copyright (C) 2001-2010 GUAN Xue-tao
   8  */
   9 #include <linux/linkage.h>
  10 #include <asm/assembler.h>
  11 #include <asm/errno.h>
  12 
  13         .text
  14         .align  5
  15 
  16 /*
  17  * Copy a string from user space to kernel space.
  18  *  r0 = dst, r1 = src, r2 = byte length
  19  * returns the number of characters copied (strlen of copied string),
  20  *  -EFAULT on exception, or "len" if we fill the whole buffer
  21  */
  22 ENTRY(__strncpy_from_user)
  23         mov     ip, r1
  24 1:      sub.a   r2, r2, #1
  25         ldrusr  r3, r1, 1, ns
  26         bfs     2f
  27         stb.w   r3, [r0]+, #1
  28         cxor.a  r3, #0
  29         bne     1b
  30         sub     r1, r1, #1      @ take NUL character out of count
  31 2:      sub     r0, r1, ip
  32         mov     pc, lr
  33 ENDPROC(__strncpy_from_user)
  34 
  35         .pushsection .fixup,"ax"
  36         .align  0
  37 9001:   mov     r3, #0
  38         stb     r3, [r0+], #0   @ null terminate
  39         mov     r0, #-EFAULT
  40         mov     pc, lr
  41         .popsection
  42