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339
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1 /*
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2 link.c
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3 Copyright © 2009 William Astle
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4
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5 This file is part of LWLINK.
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6
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7 LWLINK is free software: you can redistribute it and/or modify it under the
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8 terms of the GNU General Public License as published by the Free Software
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9 Foundation, either version 3 of the License, or (at your option) any later
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10 version.
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11
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12 This program is distributed in the hope that it will be useful, but WITHOUT
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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15 more details.
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16
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17 You should have received a copy of the GNU General Public License along with
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18 this program. If not, see <http://www.gnu.org/licenses/>.
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19
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20
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21 Resolve section and symbol addresses; handle incomplete references
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22 */
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23
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24 #include <config.h>
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25
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26 #include <stdio.h>
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27 #include <stdlib.h>
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28
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29 #include "expr.h"
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30 #include "lwlink.h"
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31 #include "util.h"
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32
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33 struct section_list *sectlist = NULL;
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34 int nsects = 0;
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35 static int nforced = 0;
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36
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37 void check_section_name(char *name, int *base, fileinfo_t *fn)
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38 {
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39 int sn;
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40
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41 if (fn -> forced == 0)
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42 return;
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43
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44 for (sn = 0; sn < fn -> nsections; sn++)
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45 {
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46 if (!strcmp(name, fn -> sections[sn].name))
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47 {
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48 // we have a match
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49 sectlist = lw_realloc(sectlist, sizeof(struct section_list) * (nsects + 1));
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50 sectlist[nsects].ptr = &(fn -> sections[sn]);
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51
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52 fn -> sections[sn].processed = 1;
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53 fn -> sections[sn].loadaddress = *base;
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54 *base += fn -> sections[sn].codesize;
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55 nsects++;
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56 }
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57 }
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58 for (sn = 0; sn < fn -> nsubs; sn++)
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59 {
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60 check_section_name(name, base, fn -> subs[sn]);
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61 }
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62 }
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63
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64 void add_matching_sections(char *name, int yesflags, int noflags, int *base);
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65 void check_section_flags(int yesflags, int noflags, int *base, fileinfo_t *fn)
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66 {
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67 int sn;
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68
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69 if (fn -> forced == 0)
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70 return;
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71
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72 for (sn = 0; sn < fn -> nsections; sn++)
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73 {
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74 // ignore if the noflags tell us to
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75 if (noflags && (fn -> sections[sn].flags & noflags))
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76 continue;
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77 // ignore unless the yesflags tell us not to
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78 if (yesflags && (fn -> sections[sn].flags & yesflags == 0))
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79 continue;
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80 // ignore it if already processed
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81 if (fn -> sections[sn].processed)
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82 continue;
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83
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84 // we have a match - now collect *all* sections of the same name!
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85 add_matching_sections(fn -> sections[sn].name, 0, 0, base);
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86
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87 // and then continue looking for sections
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88 }
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89 for (sn = 0; sn < fn -> nsubs; sn++)
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90 {
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91 check_section_flags(yesflags, noflags, base, fn -> subs[sn]);
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92 }
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93 }
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94
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95
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96
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97 void add_matching_sections(char *name, int yesflags, int noflags, int *base)
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98 {
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99 int fn;
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100 if (name)
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101 {
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102 // named section
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103 // look for all instances of a section by the specified name
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104 // and resolve base addresses and add to the list
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105 for (fn = 0; fn < ninputfiles; fn++)
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106 {
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107 check_section_name(name, base, inputfiles[fn]);
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108 }
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109 }
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110 else
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111 {
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112 // wildcard section
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113 // named section
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114 // look for all instances of a section by the specified name
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115 // and resolve base addresses and add to the list
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116 for (fn = 0; fn < ninputfiles; fn++)
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117 {
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118 check_section_flags(yesflags, noflags, base, inputfiles[fn]);
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119 }
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120 }
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121 }
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122
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123 // work out section load order and resolve base addresses for each section
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124 // make a list of sections to load in order
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125 void resolve_sections(void)
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126 {
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127 int laddr = 0;
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128 int ln, sn, fn;
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129
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130 for (ln = 0; ln < linkscript.nlines; ln++)
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131 {
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132 if (linkscript.lines[ln].loadat >= 0)
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133 laddr = linkscript.lines[ln].loadat;
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134 add_matching_sections(linkscript.lines[ln].sectname, linkscript.lines[ln].yesflags, linkscript.lines[ln].noflags, &laddr);
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135
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136 if (linkscript.lines[ln].sectname)
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137 {
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138 }
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139 else
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140 {
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141 // wildcard section
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142 // look for all sections not yet processed that match flags
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143
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144 int f = 0;
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145 int fn0, sn0;
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146 char *sname;
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147
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148 // named section
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149 // look for all instances of a section by the specified name
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150 // and resolve base addresses and add to the list
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151 for (fn0 = 0; fn0 < ninputfiles; fn0++)
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152 {
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153 for (sn0 = 0; sn0 < inputfiles[fn0] -> nsections; sn0++)
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154 {
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155 // ignore if the "no flags" bit says to
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156 if (linkscript.lines[ln].noflags && (inputfiles[fn0] -> sections[sn0].flags & linkscript.lines[ln].noflags))
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157 continue;
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158 // ignore unless the yes flags tell us not to
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159 if (linkscript.lines[ln].yesflags && (inputfiles[fn0] -> sections[sn0].flags & linkscript.lines[ln].yesflags == 0))
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160 continue;
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161 if (inputfiles[fn0] -> sections[sn0].processed == 0)
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162 {
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163 sname = inputfiles[fn0] -> sections[sn0].name;
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164 for (fn = 0; fn < ninputfiles; fn++)
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165 {
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166 for (sn = 0; sn < inputfiles[fn] -> nsections; sn++)
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167 {
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168 if (!strcmp(sname, inputfiles[fn] -> sections[sn].name))
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169 {
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170 // we have a match
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171 sectlist = lw_realloc(sectlist, sizeof(struct section_list) * (nsects + 1));
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172 sectlist[nsects].ptr = &(inputfiles[fn] -> sections[sn]);
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173
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174 inputfiles[fn] -> sections[sn].processed = 1;
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175 if (!f && linkscript.lines[ln].loadat >= 0)
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176 {
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177 f = 1;
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178 sectlist[nsects].forceaddr = 1;
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179 laddr = linkscript.lines[ln].loadat;
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180 }
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181 else
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182 {
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183 sectlist[nsects].forceaddr = 0;
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184 }
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185 inputfiles[fn] -> sections[sn].loadaddress = laddr;
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186 laddr += inputfiles[fn] -> sections[sn].codesize;
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187 nsects++;
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188 }
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189 }
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190 }
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191 }
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192 }
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193 }
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194 }
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195 }
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196
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197 // theoretically, all the base addresses are set now
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198 }
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199
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200 lw_expr_stack_t *find_external_sym_recurse(char *sym, fileinfo_t *fn)
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201 {
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202 int sn;
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203 lw_expr_stack_t *r;
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204 lw_expr_term_t *term;
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205 symtab_t *se;
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206 int val;
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207
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208 for (sn = 0; sn < fn -> nsections; sn++)
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209 {
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210 for (se = fn -> sections[sn].exportedsyms; se; se = se -> next)
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211 {
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212 if (!strcmp(sym, se -> sym))
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213 {
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214 if (!(fn -> forced))
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215 {
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216 fn -> forced = 1;
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217 nforced = 1;
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218 }
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219 val = se -> offset + fn -> sections[sn].loadaddress;
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220 r = lw_expr_stack_create();
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221 term = lw_expr_term_create_int(val & 0xffff);
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222 lw_expr_stack_push(r, term);
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223 lw_expr_term_free(term);
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224 return r;
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225 }
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226 }
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227 }
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228
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229 for (sn = 0; sn < fn -> nsubs; sn++)
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230 {
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231 r = find_external_sym_recurse(sym, fn -> subs[sn]);
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232 if (r)
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233 {
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234 if (!(fn -> forced))
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235 {
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236 nforced = 1;
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237 fn -> forced = 1;
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238 }
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239 return r;
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240 }
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241 }
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242 return NULL;
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243 }
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244
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245 // resolve all incomplete references now
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246 // anything that is unresolvable at this stage will throw an error
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247 // because we know the load address of every section now
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248 lw_expr_stack_t *resolve_sym(char *sym, int symtype, void *state)
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249 {
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250 section_t *sect = state;
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251 lw_expr_term_t *term;
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252 int val = 0, i, fn;
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253 lw_expr_stack_t *s;
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254 symtab_t *se;
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255 fileinfo_t *fp;
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256
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257 if (symtype == 1)
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258 {
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259 // local symbol
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260 if (!sym)
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261 {
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262 val = sect -> loadaddress;
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263 goto out;
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264 }
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265
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266 // start with this section
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267 for (se = sect -> localsyms; se; se = se -> next)
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268 {
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269 if (!strcmp(se -> sym, sym))
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270 {
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271 val = se -> offset + sect -> loadaddress;
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272 goto out;
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273 }
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274 }
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275 // not in this section - check all sections in this file
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276 for (i = 0; i < sect -> file -> nsections; i++)
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277 {
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278 for (se = sect -> file -> sections[i].localsyms; se; se = se -> next)
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279 {
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280 if (!strcmp(se -> sym, sym))
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281 {
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282 val = se -> offset + sect -> file -> sections[i].loadaddress;
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283 goto out;
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284 }
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285 }
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286 }
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287 // not found
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288 symerr = 1;
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289 fprintf(stderr, "Local symbol %s not found in %s:%s\n", sym, sect -> file -> filename, sect -> name);
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290 goto outerr;
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291 }
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292 else
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293 {
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294 // external symbol
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295 // read all files in order until found (or not found)
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296 if (sect)
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297 {
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298 for (fp = sect -> file; fp; fp = fp -> parent)
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299 {
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300 s = find_external_sym_recurse(sym, fp);
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301 if (s)
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302 return s;
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303 }
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304 }
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305
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306 for (fn = 0; fn < ninputfiles; fn++)
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307 {
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308 s = find_external_sym_recurse(sym, inputfiles[fn]);
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309 if (s)
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310 return s;
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311 }
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312 if (sect)
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313 {
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314 fprintf(stderr, "External symbol %s not found in %s:%s\n", sym, sect -> file -> filename, sect -> name);
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315 }
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316 else
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317 {
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318 fprintf(stderr, "External symbol %s not found\n", sym);
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319 }
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320 symerr = 1;
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321 goto outerr;
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322 }
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323 fprintf(stderr, "Shouldn't ever get here!!!\n");
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324 exit(88);
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325 out:
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326 s = lw_expr_stack_create();
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327 term = lw_expr_term_create_int(val & 0xffff);
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328 lw_expr_stack_push(s, term);
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329 lw_expr_term_free(term);
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330 return s;
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331 outerr:
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332 return NULL;
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333 }
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334
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335 void resolve_references(void)
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336 {
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337 int sn;
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338 reloc_t *rl;
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339 int rval;
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340
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341 // resolve entry point if required
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342 // this must resolve to an *exported* symbol and will resolve to the
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343 // first instance of that symbol
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344 if (linkscript.execsym)
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345 {
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346 lw_expr_stack_t *s;
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347
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348 s = resolve_sym(linkscript.execsym, 0, NULL);
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349 if (!s)
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350 {
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351 fprintf(stderr, "Cannot resolve exec address '%s'\n", linkscript.execsym);
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352 symerr = 1;
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353 }
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354 else
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355 {
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356 linkscript.execaddr = lw_expr_get_value(s);
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357 lw_expr_stack_free(s);
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358 }
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359 }
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360
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361 for (sn = 0; sn < nsects; sn++)
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362 {
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363 for (rl = sectlist[sn].ptr -> incompletes; rl; rl = rl -> next)
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364 {
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365 // do a "simplify" on the expression
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366 rval = lw_expr_reval(rl -> expr, resolve_sym, sectlist[sn].ptr);
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367
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368 // is it constant? error out if not
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369 if (rval != 0 || !lw_expr_is_constant(rl -> expr))
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370 {
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371 fprintf(stderr, "Incomplete reference at %s:%s+%02X\n", sectlist[sn].ptr -> file -> filename, sectlist[sn].ptr -> name, rl -> offset);
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372 symerr = 1;
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373 }
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374 else
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375 {
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376 // put the value into the relocation address
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377 rval = lw_expr_get_value(rl -> expr);
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378 if (rl -> flags & RELOC_8BIT)
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379 {
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380 sectlist[sn].ptr -> code[rl -> offset] = rval & 0xff;
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381 }
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382 else
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383 {
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384 sectlist[sn].ptr -> code[rl -> offset] = (rval >> 8) & 0xff;
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385 sectlist[sn].ptr -> code[rl -> offset + 1] = rval & 0xff;
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386 }
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387 }
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388 }
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389 }
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390
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391 if (symerr)
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392 exit(1);
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393 }
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394
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395 /*
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396 This is just a pared down version of the algo for resolving references.
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397 */
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398 void resolve_files(void)
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399 {
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400 int sn;
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401 int fn;
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402 reloc_t *rl;
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403 lw_expr_stack_t *te;
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404
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405 int rval;
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406
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407 // resolve entry point if required
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408 // this must resolve to an *exported* symbol and will resolve to the
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409 // first instance of that symbol
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410 if (linkscript.execsym)
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411 {
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412 lw_expr_stack_t *s;
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413
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414 s = resolve_sym(linkscript.execsym, 0, NULL);
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415 if (!s)
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416 {
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417 fprintf(stderr, "Cannot resolve exec address '%s'\n", linkscript.execsym);
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418 symerr = 1;
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419 }
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420 }
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421
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422 do
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423 {
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424 nforced = 0;
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425 for (fn = 0; fn < ninputfiles; fn++)
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426 {
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427 if (inputfiles[fn] -> forced == 0)
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428 continue;
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429
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430 for (sn = 0; sn < inputfiles[fn] -> nsections; sn++)
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431 {
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432 for (rl = inputfiles[fn] -> sections[sn].incompletes; rl; rl = rl -> next)
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433 {
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434 // do a "simplify" on the expression
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435 te = lw_expr_stack_dup(rl -> expr);
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436 rval = lw_expr_reval(te, resolve_sym, &(inputfiles[fn] -> sections[sn]));
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437
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438 // is it constant? error out if not
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439 if (rval != 0 || !lw_expr_is_constant(te))
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440 {
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441 fprintf(stderr, "Incomplete reference at %s:%s+%02X\n", inputfiles[fn] -> filename, inputfiles[fn] -> sections[sn].name, rl -> offset);
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442 symerr = 1;
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443 }
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444 lw_expr_stack_free(te);
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445 }
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446 }
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447 }
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448 }
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|
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449 while (nforced == 1);
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450
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451 if (symerr)
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452 exit(1);
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453
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454 // theoretically, all files referenced by other files now have "forced" set to 1
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455 for (fn = 0; fn < ninputfiles; fn++)
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456 {
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457 if (inputfiles[fn] -> forced == 1)
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458 continue;
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459
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460 fprintf(stderr, "Warning: %s (%d) does not resolve any symbols\n", inputfiles[fn] -> filename, fn);
|
|
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461 }
|
|
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462 }
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