usr/src/cmd/sgs/librtld/i386/_relocate.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 (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #include        <string.h>
  28 #include        "machdep.h"
  29 #include        <krtld/reloc.h>
  30 #include        "_librtld.h"
  31 #include        "_elf.h"
  32
  33 /*
  34  * Undo relocations that have been applied to a memory image.  Basically this
  35  * involves copying the original files relocation offset into the new image
  36  * being created.
  37  */
  38 void
  39 undo_reloc(void *vrel, uchar_t *oaddr, uchar_t *iaddr, Reloc *reloc)
  40 {
  41         Rel     *rel = vrel;
  42         /* LINTED */
  43         ulong_t *_oaddr = (ulong_t *)oaddr;
  44         /* LINTED */
  45         ulong_t *_iaddr = (ulong_t *)iaddr;
  46
  47         switch (ELF_R_TYPE(rel->r_info, M_MACH)) {
  48         case R_386_NONE:
  49                 break;
  50
  51         case R_386_COPY:
  52                 (void) memset(oaddr, 0, (size_t)reloc->r_size);
  53                 break;
  54
  55         case R_386_JMP_SLOT:
  56                 if (_iaddr)
  57                         *_oaddr = *_iaddr + reloc->r_value;
  58                 else
  59                         *_oaddr = reloc->r_value;
  60                 break;
  61
  62         default:
  63                 if (_iaddr)
  64                         *_oaddr = *_iaddr;
  65                 else
  66                         *_oaddr = 0;
  67                 break;
  68         }
  69 }
  70
  71 /*
  72  * Copy a relocation record and increment its value.  The record must reflect
  73  * the new address to which this image is fixed.  Note that .got entries
  74  * associated with .plt's must be fixed to the new base address.
  75  */
  76 void
  77 inc_reloc(void *vnrel, void *vorel, Reloc *reloc, uchar_t *oaddr,
  78     uchar_t *iaddr)
  79 {
  80         Rel     *nrel = vnrel;
  81         Rel     *orel = vorel;
  82         /* LINTED */
  83         ulong_t *_oaddr = (ulong_t *)oaddr;
  84         /* LINTED */
  85         ulong_t *_iaddr = (ulong_t *)iaddr;
  86
  87         if (ELF_R_TYPE(nrel->r_info, M_MACH) == R_386_JMP_SLOT) {
  88                 if (_iaddr)
  89                         *_oaddr = *_iaddr + reloc->r_value;
  90                 else
  91                         *_oaddr = reloc->r_value;
  92         }
  93
  94         *nrel = *orel;
  95         nrel->r_offset += reloc->r_value;
  96 }
  97
  98 /*
  99  * Clear a relocation record.  The relocation has been applied to the image and
 100  * thus the relocation must not occur again.
 101  */
 102 void
 103 clear_reloc(void *vrel)
 104 {
 105         Rel     *rel = vrel;
 106
 107         rel->r_offset = 0;
 108         rel->r_info = ELF_R_INFO(0, R_386_NONE);
 109 }
 110
 111 /*
 112  * Apply a relocation to an image being built from an input file.  Use the
 113  * runtime linkers routines to do the necessary magic.
 114  */
 115 void
 116 apply_reloc(void *vrel, Reloc *reloc, const char *name, uchar_t *oaddr,
 117     Rt_map *lmp)
 118 {
 119         Rel     *rel = vrel;
 120         Xword   type = ELF_R_TYPE(rel->r_info, M_MACH);
 121         Word    value = reloc->r_value;
 122
 123         if (type == R_386_JMP_SLOT) {
 124                 uintptr_t       addr, vaddr;
 125
 126                 if (FLAGS(lmp) & FLG_RT_FIXED)
 127                         vaddr = 0;
 128                 else
 129                         vaddr = ADDR(lmp);
 130                 addr = (uintptr_t)oaddr - rel->r_offset;
 131                 /* LINTED */
 132                 (void) elf_plt_write((uintptr_t)addr, vaddr, rel,
 133                     (uintptr_t)value, reloc->r_pltndx);
 134
 135         } else if (type == R_386_COPY) {
 136                 (void) memcpy((void *)oaddr, (void *)value,
 137                     (size_t)reloc->r_size);
 138         } else {
 139                 (void) do_reloc_rtld(type, oaddr, &value, reloc->r_name, name,
 140                     LIST(lmp));
 141         }
 142 }