root/arch/mips/lib/strncpy_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, 1999 by Ralf Baechle
   7  * Copyright (C) 2011 MIPS Technologies, Inc.
   8  */
   9 #include <linux/errno.h>
  10 #include <asm/asm.h>
  11 #include <asm/asm-offsets.h>
  12 #include <asm/export.h>
  13 #include <asm/regdef.h>
  14 
  15 #define EX(insn,reg,addr,handler)                       \
  16 9:      insn    reg, addr;                              \
  17         .section __ex_table,"a";                        \
  18         PTR     9b, handler;                            \
  19         .previous
  20 
  21 /*
  22  * Returns: -EFAULT if exception before terminator, N if the entire
  23  * buffer filled, else strlen.
  24  */
  25 
  26 /*
  27  * Ugly special case have to check: we might get passed a user space
  28  * pointer which wraps into the kernel space.  We don't deal with that.  If
  29  * it happens at most some bytes of the exceptions handlers will be copied.
  30  */
  31 
  32         .macro __BUILD_STRNCPY_ASM func
  33 LEAF(__strncpy_from_\func\()_asm)
  34         LONG_L          v0, TI_ADDR_LIMIT($28)  # pointer ok?
  35         and             v0, a1
  36         bnez            v0, .Lfault\@
  37 
  38         move            t0, zero
  39         move            v1, a1
  40 .ifeqs "\func","kernel"
  41 1:      EX(lbu, v0, (v1), .Lfault\@)
  42 .else
  43 1:      EX(lbue, v0, (v1), .Lfault\@)
  44 .endif
  45         PTR_ADDIU       v1, 1
  46         R10KCBARRIER(0(ra))
  47         sb              v0, (a0)
  48         beqz            v0, 2f
  49         PTR_ADDIU       t0, 1
  50         PTR_ADDIU       a0, 1
  51         bne             t0, a2, 1b
  52 2:      PTR_ADDU        v0, a1, t0
  53         xor             v0, a1
  54         bltz            v0, .Lfault\@
  55         move            v0, t0
  56         jr              ra                      # return n
  57         END(__strncpy_from_\func\()_asm)
  58 
  59 .Lfault\@:
  60         li              v0, -EFAULT
  61         jr              ra
  62 
  63         .section        __ex_table,"a"
  64         PTR             1b, .Lfault\@
  65         .previous
  66 
  67         .endm
  68 
  69 #ifndef CONFIG_EVA
  70         /* Set aliases */
  71         .global __strncpy_from_user_asm
  72         .set __strncpy_from_user_asm, __strncpy_from_kernel_asm
  73 EXPORT_SYMBOL(__strncpy_from_user_asm)
  74 #endif
  75 
  76 __BUILD_STRNCPY_ASM kernel
  77 EXPORT_SYMBOL(__strncpy_from_kernel_asm)
  78 
  79 #ifdef CONFIG_EVA
  80         .set push
  81         .set eva
  82 __BUILD_STRNCPY_ASM user
  83         .set pop
  84 EXPORT_SYMBOL(__strncpy_from_user_asm)
  85 #endif