arch/x86/kernel/os/copy_subr.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 /*
  30  * Miscellaneous C routines for copying data around without
  31  * descending into assembler.  Compilers are pretty good at
  32  * scheduling instructions, and humans are pretty hopeless at
  33  * writing correct assembler.
  34  */
  35
  36 #include <sys/types.h>
  37 #include <sys/systm.h>
  38 #include <sys/errno.h>
  39 #include <sys/param.h>
  40
  41 /*
  42  * copyinstr_noerr and copyoutstr_noerr can be implemented completely
  43  * in C on machines with shared user and kernel context.
  44  */
  45 static int
  46 copystr_nofault(const char *src, char *dst, size_t maxlength,
  47     size_t *lencopied)
  48 {
  49         int error = 0;
  50         size_t leftover;
  51
  52         if ((leftover = maxlength) == 0)
  53                 error = ENAMETOOLONG;
  54         else
  55                 do {
  56                         leftover--;
  57                         if ((*dst++ = *src++) == '\0')
  58                                 break;
  59                         if (leftover == 0) {
  60                                 error = ENAMETOOLONG;
  61                                 break;
  62                         }
  63                 /*CONSTCOND*/
  64                 } while (1);
  65
  66         if (lencopied)
  67                 *lencopied = maxlength - leftover;
  68         return (error);
  69 }
  70
  71
  72 int
  73 copyinstr_noerr(const char *uaddr, char *kaddr, size_t maxlength,
  74     size_t *lencopied)
  75 {
  76         char *ua = (char *)uaddr;
  77
  78         ASSERT((uintptr_t)kaddr > kernelbase);
  79
  80         if ((uintptr_t)ua > kernelbase) {
  81                 /*
  82                  * force fault at kernelbase
  83                  */
  84                 ua = (char *)kernelbase;
  85         }
  86         return (copystr_nofault(ua, kaddr, maxlength, lencopied));
  87 }
  88
  89 int
  90 copyoutstr_noerr(const char *kaddr, char *uaddr, size_t maxlength,
  91     size_t *lencopied)
  92 {
  93         char *ua = (char *)uaddr;
  94
  95         ASSERT((uintptr_t)kaddr > kernelbase);
  96
  97         if ((uintptr_t)ua > kernelbase) {
  98                 /*
  99                  * force fault at kernelbase
 100                  */
 101                 ua = (char *)kernelbase;
 102         }
 103         return (copystr_nofault(kaddr, ua, maxlength, lencopied));
 104 }