arch/mips/lib/strlen_user.S

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (c) 1996, 1998, 1999, 2004 by Ralf Baechle
   7  * Copyright (c) 1999 Silicon Graphics, Inc.
   8  */
   9 #include <asm/asm.h>
  10 #include <asm/offset.h>
  11 #include <asm/regdef.h>
  12
  13 #define EX(insn,reg,addr,handler)                       \
  14 9:      insn    reg, addr;                              \
  15         .section __ex_table,"a";                        \
  16         PTR     9b, handler;                            \
  17         .previous
  18
  19 /*
  20  * Return the size of a string (including the ending 0)
  21  *
  22  * Return 0 for error
  23  */
  24 LEAF(__strlen_user_asm)
  25         LONG_L          v0, TI_ADDR_LIMIT($28)  # pointer ok?
  26         and             v0, a0
  27         bnez            v0, fault
  28
  29 FEXPORT(__strlen_user_nocheck_asm)
  30         move            v0, a0
  31 1:      EX(lb, t0, (v0), fault)
  32         PTR_ADDIU       v0, 1
  33         bnez            t0, 1b
  34         PTR_SUBU        v0, a0
  35         jr              ra
  36         END(__strlen_user_asm)
  37
  38 fault:  move            v0, zero
  39         jr              ra