arch/avr32/lib/strncpy_from_user.S

   1 /*
   2  * Copy to/from userspace with optional address space checking.
   3  *
   4  * Copyright 2004-2006 Atmel Corporation
   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/errno.h>
  11
  12 #include <asm/page.h>
  13 #include <asm/thread_info.h>
  14 #include <asm/asm.h>
  15
  16         /*
  17          * long strncpy_from_user(char *dst, const char *src, long count)
  18          *
  19          * On success, returns the length of the string, not including
  20          * the terminating NUL.
  21          *
  22          * If the string is longer than count, returns count
  23          *
  24          * If userspace access fails, returns -EFAULT
  25          */
  26         .text
  27         .align  1
  28         .global strncpy_from_user
  29         .type   strncpy_from_user, "function"
  30 strncpy_from_user:
  31         mov     r9, -EFAULT
  32         branch_if_kernel r8, __strncpy_from_user
  33         ret_if_privileged r8, r11, r10, r9
  34
  35         .global __strncpy_from_user
  36         .type   __strncpy_from_user, "function"
  37 __strncpy_from_user:
  38         cp.w    r10, 0
  39         reteq   0
  40
  41         mov     r9, r10
  42
  43 1:      ld.ub   r8, r11++
  44         st.b    r12++, r8
  45         cp.w    r8, 0
  46         breq    2f
  47         sub     r9, 1
  48         brne    1b
  49
  50 2:      sub     r10, r9
  51         retal   r10
  52
  53         .section .fixup, "ax"
  54         .align  1
  55 3:      mov     r12, -EFAULT
  56         retal   r12
  57
  58         .section __ex_table, "a"
  59         .align  2
  60         .long   1b, 3b