LXR linux/arch/mips/lib/strncpy

   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 */
   8#include <linux/errno.h>
   9#include <asm/asm.h>
  10#include <asm/asm-offsets.h>
  11#include <asm/regdef.h>
  12
  13#define EX(insn,reg,addr,handler)                       \
  149:      insn    reg, addr;                              \
  15        .section __ex_table,"a";                        \
  16        PTR     9b, handler;                            \
  17        .previous
  18
  19/*
  20 * Returns: -EFAULT if exception before terminator, N if the entire
  21 * buffer filled, else strlen.
  22 */
  23
  24/*
  25 * Ugly special case have to check: we might get passed a user space
  26 * pointer which wraps into the kernel space.  We don't deal with that.  If
  27 * it happens at most some bytes of the exceptions handlers will be copied.
  28 */
  29
  30LEAF(__strncpy_from_user_asm)
  31        LONG_L          v0, TI_ADDR_LIMIT($28)  # pointer ok?
  32        and             v0, a1
  33        bnez            v0, .Lfault
  34
  35FEXPORT(__strncpy_from_user_nocheck_asm)
  36        move            v0, zero
  37        move            v1, a1
  38        .set            noreorder
  391:      EX(lbu, t0, (v1), .Lfault)
  40        PTR_ADDIU       v1, 1
  41        R10KCBARRIER(0(ra))
  42        beqz            t0, 2f
  43         sb             t0, (a0)
  44        PTR_ADDIU       v0, 1
  45        .set            reorder
  46        PTR_ADDIU       a0, 1
  47        bne             v0, a2, 1b
  482:      PTR_ADDU        t0, a1, v0
  49        xor             t0, a1
  50        bltz            t0, .Lfault
  51        jr              ra                      # return n
  52        END(__strncpy_from_user_asm)
  53
  54.Lfault:        li              v0, -EFAULT
  55        jr              ra
  56
  57        .section        __ex_table,"a"
  58        PTR             1b, .Lfault
  59        .previous
  60