OpenCores
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Rev 60 → Rev 61

/linker1.cpp
0,0 → 1,2109
/**************************** linker.cpp ***********************************
* Author: Agner Fog
* date created: 2017-11-14
* Last modified: 2021-05-28
* Version: 1.11
* Project: Binary tools for ForwardCom instruction set
* Description:
* This module contains the linker.
*
* Copyright 2017-2021 GNU General Public License v. 3 http://www.gnu.org/licenses
*****************************************************************************/
 
/* Overview of data structures used during linking process
-------------------------------------------------------
symbolImports: List of imported symbols that need to be resolved.
Includes symbol name and source module
symbolExports: List of public symbols that can be targets for symbolImports.
Includes symbol name and module or library
libraries: Library files to include in symbol search
libmodules: List of library modules that will be extracted as object files
modules1: Metabuffer containing all the object files to add
modules2: Same. Also includes object files extracted from libraries
sections: Index to sections to be extracted from object files and library modules.
Sorted in the order in which they should occur in the executable file
sections2: Same as sections. Sorted by module and section index. Used for re-finding a section
communalSections: List of communal sections. Some of these will be copied to sections and
sections2 when needed
symbolXref: Cross reference between module-local symbol indexes and indexes in relinkable executable file
unresWeakSym: List of unresolved weak symbols. Includes indexes in relinkable executable file
eventData: List of event records
 
Each of the elements in modules1/2 is a complete CELF object containing its own data structures,
including sectionHeaders, symbols, stringBuffer, and relocations.
 
outFile is also a complete CELF object containing its own data structures, including
programHeaders, sectionHeaders, symbols, stringBuffer, and relocations.
 
*/
 
#include "stdafx.h"
 
// define code of dummy function for unresolved weak externals
// and unresolved functions of incomplete executable file:
static const uint32_t unresolvedFunctionN = 2;
static const uint32_t unresolvedFunction[unresolvedFunctionN] = {
0x79800200, // tiny instructions: int64 r0 = 0; double v0 = 0
// 0x78000200, // tiny instructions: int64 r0 = 0; v0 = clear()
0x67C00000 // instruction: return
};
static const uint32_t unresolvedReguse1 = 1;
static const uint32_t unresolvedReguse2 = 1;
 
// run the linker
void CLinker::go() {
// write text on stdout
feedBackText1();
 
if (cmd.job == CMDL_JOB_RELINK) {
// read pre-existing executable file
loadExeFile();
relinkable = true; relinking = true;
if (err.number()) return;
}
 
// read specified object files and library files
fillBuffers();
if (err.number()) return;
 
// make list of imported and exported symbols
makeSymbolList();
if (err.number()) return;
 
// match lists of imported and exported symbols
matchSymbols();
if (err.number()) return;
 
// search libraries for imported symbols
librarySearch();
if (err.number()) return;
 
// write feedback to console
feedBackText2();
 
// check for duplicate symbols
checkDuplicateSymbols();
if (err.number()) return;
 
// get imported library modules into modules2 buffer
readLibraryModules();
if (err.number()) return;
 
// make list of all sections
makeSectionList();
if (err.number()) return;
 
// make program headers and assign addresses to sections
makeProgramHeaders();
if (err.number()) return;
 
// put values into all cross references
relocate();
if (err.number()) return;
 
// make sorted event list
makeEventList();
 
// copy sections to output file
copySections();
 
// copy symbols to output file
copySymbols();
 
// copy relocation records to output file if needed
copyRelocations();
if (err.number()) return;
 
// make executable file header
makeFileHeader();
 
// join sections into executable file
outFile.join(&fileHeader);
if (err.number()) return;
 
// make link map
if (cmd.outputListFile) {
CELF exefile;
exefile.copy(outFile);
exefile.parseFile();
const char * listfilename = cmd.getFilename(cmd.outputListFile);
FILE * fp = fopen(listfilename, "w");
fprintf(fp, "\nLink map of %s\n", cmd.getFilename(cmd.outputFile));
exefile.makeLinkMap(fp);
fclose(fp);
}
 
if (cmd.outputType == FILETYPE_FWC_HEX) {
// make hexadecimal file
CFileBuffer hexfile;
outFile.makeHexBuffer() >> hexfile;
hexfile.write(cmd.getFilename(cmd.outputFile));
}
else {
// write output file
outFile.write(cmd.getFilename(cmd.outputFile));
}
}
 
CLinker::CLinker() {
// Constructor
zeroAllMembers(fileHeader); // initialize file header
relinking = false;
relinkable = (cmd.fileOptions & CMDL_FILE_RELINKABLE) != 0;
symbolNameBuffer.pushString(""); // make sure name = 0 gives empty string
}
 
// write feedback text on stdout
void CLinker::feedBackText1() {
if (cmd.verbose) { // tell what we are doing
if (cmd.verbose > 1) printf("\nForwardCom linker v. %i.%02i", FORWARDCOM_VERSION, FORWARDCOM_SUBVERSION);
if (cmd.job == CMDL_JOB_LINK) {
printf("\nLinking file %s", cmd.getFilename(cmd.outputFile));
}
else {
printf("\nRelinking file %s to file %s", cmd.getFilename(cmd.inputFile), cmd.getFilename(cmd.outputFile));
}
}
}
 
// load specified object files and library files into buffers
void CLinker::fillBuffers() {
uint32_t i; // loop counter
const char * fname; // file name
 
// count number of modules and libraries on command line, and number of relinkable modules and libraries
countModules();
 
// allocate metabuffers
modules1.setSize(numRelinkObjects + numObjects);
libraries.setSize(numLibraries + numRelinkLibraries + 1); // libraries[0] is not used
 
// get preserved modules if relinking
if (cmd.job == CMDL_JOB_RELINK) getRelinkObjects();
 
// read files into these buffers
uint32_t iObject = numRelinkObjects; // object file index
uint32_t iLibrary = 0; // library file index
 
if (cmd.verbose && numObjects) printf("\nAdding object files:");
 
// loop through commands. get object files and libraries
for (i = 0; i < cmd.lcommands.numEntries(); i++) {
if ((cmd.lcommands[i].command & 0xFF) == CMDL_LINK_ADDMODULE) {
// name of object file
fname = cmd.getFilename(cmd.lcommands[i].filename);
// write name
if (cmd.verbose) printf(" %s", fname);
// read object file
modules1[iObject].read(fname);
modules1[iObject].moduleName = cmd.fileNameBuffer.pushString(removePath(fname));
modules1[iObject].library = 0;
modules1[iObject].relinkable = (cmd.lcommands[i].command & CMDL_LINK_RELINKABLE) != 0;
 
// remove colons from name
char *nm = &cmd.fileNameBuffer.get<char>(modules1[iObject].moduleName);
for (int s = 0; s < (int)strlen(nm); s++) {
if (nm[s] == ':' || nm[s] <= ' ') nm[s] = '_';
}
if (err.number()) continue;
// check type
if (modules1[iObject].getFileType() != FILETYPE_FWC) {
err.submit(ERR_LINK_FILE_TYPE, fname);
return;
}
iObject++;
}
else if ((cmd.lcommands[i].command & 0xFF) == CMDL_LINK_ADDLIBRARY) {
iLibrary++;
// name of library file
fname = cmd.getFilename(cmd.lcommands[i].filename);
// read library file
libraries[iLibrary].read(fname);
libraries[iLibrary].relinkable = (cmd.lcommands[i].command & CMDL_LINK_RELINKABLE) != 0;
libraries[iLibrary].libraryName = cmd.fileNameBuffer.pushString(removePath(fname));
 
// remove colons and whitespace from name
char *nm = &cmd.fileNameBuffer.get<char>(libraries[iLibrary].libraryName);
for (int s = 0; s < (int)strlen(nm); s++) {
if (nm[s] == ':' || nm[s] <= ' ') nm[s] = '_';
}
if (err.number()) continue;
// check type
uint32_t ftype = libraries[iLibrary].getFileType();
if ((ftype != FILETYPE_LIBRARY && ftype != FILETYPE_FWC_LIB) || !libraries[iLibrary].isForwardCom()) {
err.submit(ERR_LINK_FILE_TYPE_LIB, fname);
return;
}
}
else if ((cmd.lcommands[i].command & 0xFF) == CMDL_LINK_ADDLIBMODULE) {
// add module explicitly from library
 
// name of module
fname = cmd.getFilename(cmd.lcommands[i].filename);
 
// extract module from last library
if (iLibrary == 0) { // no library specified
err.submit(ERR_LINK_MODULE_NOT_FOUND, fname, "none");
continue;
}
// library name
const char * libName = cmd.getFilename(libraries[iLibrary].libraryName);
// find module
uint32_t moduleOs = libraries[iLibrary].findMember(cmd.lcommands[i].filename);
if (moduleOs == 0) { // module not found in library
err.submit(ERR_LINK_MODULE_NOT_FOUND, fname, libName);
continue;
}
// write name
if (cmd.verbose) printf(" %s:%s", libName, fname);
 
// read object file
modules1[iObject].push(libraries[iLibrary].buf() + moduleOs + (uint32_t)sizeof(SUNIXLibraryHeader),
libraries[iLibrary].getMemberSize(moduleOs));
modules1[iObject].moduleName = cmd.lcommands[i].filename;
modules1[iObject].library = iLibrary;
modules1[iObject].relinkable = (cmd.lcommands[i].command & CMDL_LINK_RELINKABLE) != 0;
iObject++;
}
}
 
// get recovered libraries if relinking
if (numRelinkLibraries) getRelinkLibraries();
}
 
// count number of modules and libraries to add
void CLinker::countModules() {
uint32_t i; // loop counter
int32_t j; // loop counter
const char * fname; // file name
numObjects = 0; // number of object files
numLibraries = 0; // number of libraries
 
// count number of object files and library files on command line
for (i = 0; i < cmd.lcommands.numEntries(); i++) {
if ((uint8_t)cmd.lcommands[i].command == CMDL_LINK_ADDMODULE || (uint8_t)cmd.lcommands[i].command == CMDL_LINK_ADDLIBRARY) {
// name of module
fname = cmd.getFilename(cmd.lcommands[i].filename);
// is it a library?
for (j = (int32_t)strlen(fname) - 1; j > 0; j--) {
if (fname[j] == '.') break;
}
if ((j > 0 && strncasecmp_(fname + j, ".li", 3) == 0 ) || (fname[j+1] == 'a' && fname[j+2] == 0)) {
// this is a library
numLibraries++;
cmd.lcommands[i].command = CMDL_LINK_ADDLIBRARY | (cmd.lcommands[i].command & CMDL_LINK_RELINKABLE);
}
else {
// assume that this is an object file
numObjects++;
}
}
if ((cmd.lcommands[i].command & 0xFF) == CMDL_LINK_ADDLIBMODULE) {
// object module from library file
numObjects++;
}
if (cmd.lcommands[i].command & CMDL_LINK_RELINKABLE) {
// output file is relinkable
relinkable = true;
}
}
// count number of object files and libraries to reuse if relinking
countReusedModules();
}
 
// make list of imported and exported symbols
void CLinker::makeSymbolList() {
uint32_t modul; // module index
SSymbolEntry sym; // symbol record
zeroAllMembers(sym);
unresolvedWeak = 0; // unresolved weak imports: 1: constant, 2: readonly ip data, 4: writeable datap data, 8: function
unresolvedWeakNum = 0; // number of unresolved weak imports for writeable data
 
// loop through modules
for (modul = 0; modul < modules1.numEntries(); modul++) {
if (modules1[modul].dataSize() == 0) continue;
// get exported symbols
modules1[modul].listSymbols(&symbolNameBuffer, &symbolExports, modul, 0, 1);
// get imported symbols
modules1[modul].listSymbols(&symbolNameBuffer, &symbolImports, modul, 0, 2);
}
// add special symbols as weak. value will be set later
sym.name = symbolNameBuffer.pushString("__ip_base");
sym.st_bind = STB_WEAK;
sym.library = 0xFFFFFFFE;
sym.st_other = SHF_IP;
sym.symindex = 1;
sym.member = 0;
sym.status = 3;
symbolExports.push(sym);
symbolImports.push(sym);
sym.name = symbolNameBuffer.pushString("__datap_base");
sym.st_other = SHF_DATAP;
sym.symindex = 2;
symbolExports.push(sym);
symbolImports.push(sym);
sym.name = symbolNameBuffer.pushString("__threadp_base");
sym.st_other = SHF_THREADP;
sym.symindex = 3;
symbolExports.push(sym);
symbolImports.push(sym);
sym.name = symbolNameBuffer.pushString("__event_table");
sym.st_other = SHF_IP;
sym.symindex = 4;
symbolExports.push(sym);
symbolImports.push(sym);
sym.name = symbolNameBuffer.pushString("__event_table_num");
sym.st_other = 0;
sym.symindex = 5;
symbolExports.push(sym);
symbolImports.push(sym);
// make import symbol __entry_point
sym.name = symbolNameBuffer.pushString("__entry_point");
sym.st_other = 0;
sym.symindex = 6;
sym.status = 0;
sym.st_bind = STB_GLOBAL;
symbolImports.push(sym);
// sort symbols by name for easy search
symbolExports.sort();
#if 0 // debug: list exported symbols
for (uint32_t s = 0; s < symbolExports.numEntries(); s++) {
printf("\n>%s", symbolNameBuffer.buf() + symbolExports[s].name);
}
#endif
}
 
// match lists of imported and exported symbols
void CLinker::matchSymbols() {
uint32_t sym; // symbol index
int32_t found;
for (sym = 0; sym < symbolImports.numEntries(); sym++) {
// imported symbol name
if (!(symbolImports[sym].status & 2)) {
// symbol name not already resolved
// search for this name in list of exported symbols
SSymbolEntry sym1 = symbolImports[sym];
sym1.st_bind = STB_IGNORE; // ignore weak/strong difference
found = symbolExports.findFirst(sym1);
if (found >= 0) symbolImports[sym].status |= 2; // symbol has been matched
}
}
}
 
// search libraries for imported symbols
void CLinker::librarySearch() {
bool newImports = true; // new modules have additional imports to resolve
uint32_t sym; // symbol index
uint32_t lib; // library index
uint32_t m; // module index
const char * symname = 0; // name of symbol to find
uint32_t moduleOs; // offset to module in library
SLibraryModule modul; // identifyer of library module to add
// repeat search as long as new modules have additional imports to resolve
while (newImports) {
// loop through symbols
for (sym = 0; sym < symbolImports.numEntries(); sym++) {
if ((symbolImports[sym].status & 6) == 0 && !(symbolImports[sym].st_bind & STB_WEAK)) {
// symbol name
symname = symbolNameBuffer.getString(symbolImports[sym].name);
// symbol is unresolved and not weak. search for it in all libraries
for (lib = 1; lib < libraries.numEntries(); lib++) {
moduleOs = libraries[lib].findSymbol(symname);
if (moduleOs) {
// symbol found. add module to list if it is not already there
symbolImports[sym].status = 2;
modul.library = lib;
modul.offset = moduleOs;
libmodules.addUnique(modul);
break;
}
}
if (lib == libraries.numEntries()) {
// strong symbol not found. make error message
// get module name
const char * moduleName = "[fixed]";
uint32_t modul = symbolImports[sym].member;
if (modul > 0 && modul < modules1.numEntries()) {
uint32_t mn = modules1[modul].moduleName;
moduleName = cmd.getFilename(mn);
}
symbolImports[sym].status |= 4; // avoid reporting same unresolved symbol more than once
symbolImports[sym].st_bind = STB_UNRESOLVED;
fileHeader.e_flags |= EF_INCOMPLETE; // file is incomplete when there are unresolved symbols
if (cmd.fileOptions & CMDL_FILE_INCOMPLETE) { //incomplete file allowed. warn only
err.submit(ERR_LINK_UNRESOLVED_WARN, symname, moduleName);
}
else { //incomplete file not allowed. fatal error
err.submit(ERR_LINK_UNRESOLVED, symname, moduleName);
}
}
}
}
 
// loop through new library modules
newImports = false;
for (m = 0; m < libmodules.numEntries(); m++) {
if (!(libmodules[m].library & 0x80000000)) {
// this module has not been added before
libmodules[m].library |= 0x80000000;
// library and offset
lib = libmodules[m].library & 0x7FFFFFFF;
moduleOs = libmodules[m].offset;
// put member into buffer in order to extract symbols
memberBuffer.setSize(0);
memberBuffer.push(libraries[lib].buf() + moduleOs + (uint32_t)sizeof(SUNIXLibraryHeader),
libraries[lib].getMemberSize(moduleOs));
// check if this is a ForwardCom object file
int fileType = memberBuffer.getFileType();
if (fileType != FILETYPE_FWC) {
err.submit(ERR_LIBRARY_MEMBER_TYPE,
libraries[lib].getMemberName(moduleOs),
CFileBuffer::getFileFormatName(fileType));
return;
}
memberBuffer.relinkable = libraries[lib].relinkable;
// get names of exported symbols from ELF file
memberBuffer.listSymbols(&symbolNameBuffer, &symbolExports, moduleOs, lib, 1);
uint32_t numImports = symbolImports.numEntries();
// get names of imported symbols from ELF file
memberBuffer.listSymbols(&symbolNameBuffer, &symbolImports, moduleOs, lib, 2);
if (symbolImports.numEntries() > numImports) {
// this library module has new imports to resolve
newImports = true;
}
}
}
if (err.number()) return;
// new symbols have been added. sort list again
symbolExports.sort();
// match all new symbol exports to imports
matchSymbols();
}
// search for unresolved weak imports
for (sym = 0; sym < symbolImports.numEntries(); sym++) {
if ((symbolImports[sym].status & 3) == 0 && (symbolImports[sym].st_bind & STB_WEAK)) {
// weak symbol not resolved. make a zero dummy for it
symbolImports[sym].status |= 1; // avoid counting same unresolved symbol more than once
// unresolved weak imports:
// 1: constant, 2: readonly ip data, 4: writeable datap data,
// 8: threadp, 0x10: function
switch (symbolImports[sym].st_other & (SHF_BASEPOINTER | STV_EXEC)) {
case 0: // constant
unresolvedWeak |= 1; break;
case STV_IP:
unresolvedWeak |= 2; break;
case STV_DATAP:
unresolvedWeak |= 4; unresolvedWeakNum++;
break;
case STV_THREADP:
unresolvedWeak |= 8; break;
case STV_IP | STV_EXEC:
unresolvedWeak |= 0x10; break;
}
}
}
// remove check bit
for (m = 0; m < libmodules.numEntries(); m++) {
libmodules[m].library &= 0x7FFFFFFF;
}
symbolImports.sort();
}
 
// check for duplicate public symbols, except weak symbols
void CLinker::checkDuplicateSymbols() {
uint32_t sym1, sym2; // index into symbolExports
uint32_t text; // index to text in cmd.fileNameBuffer
const char * name1, * name2; // library and module names
for (sym1 = 0; sym1 < symbolExports.numEntries(); sym1++) {
if (!(symbolExports[sym1].st_bind & STB_WEAK)) {
sym2 = sym1 + 1;
while (sym2 < symbolExports.numEntries() && symbolExports[sym2] == symbolExports[sym1]) {
// symbol 2 has same name
if (!(symbolExports[sym2].st_bind & STB_WEAK)) {
// name clash. make complete list of modules containing this symbol name
text = cmd.fileNameBuffer.dataSize();
uint32_t num = symbolExports.findAll(0, symbolExports[sym1]);
for (sym2 = sym1; sym2 < sym1 + num; sym2++) {
if (!(symbolExports[sym2].st_bind & STB_WEAK)) {
if (sym2 != sym1) {
cmd.fileNameBuffer.push(", ", 2); // insert comma, except before first name
}
if (symbolExports[sym2].library) {
// symbol is in a library. get library name
uint32_t lib = symbolExports[sym2].library; // library number
name1 = cmd.getFilename(libraries[lib].libraryName);
cmd.fileNameBuffer.push(name1, (uint32_t)strlen(name1));
cmd.fileNameBuffer.push(":", 1);
// get module name
name2 = libraries[lib].getMemberName(symbolExports[sym2].member);
cmd.fileNameBuffer.push(name2, (uint32_t)strlen(name2));
}
else {
// object module. get name
uint32_t m = symbolExports[sym2].member;
if (m < modules2.numEntries()) {
name2 = cmd.getFilename(modules2[m].moduleName);
cmd.fileNameBuffer.push(name2, (uint32_t)strlen(name2));
}
else if (m < modules1.numEntries()) {
name2 = cmd.getFilename(modules1[m].moduleName);
cmd.fileNameBuffer.push(name2, (uint32_t)strlen(name2));
}
}
}
}
const char * symname = symbolNameBuffer.getString(symbolExports[sym1].name);
err.submit(ERR_LINK_DUPLICATE_SYMBOL, symname, cmd.getFilename(text));
// we are finished with this symbol name
sym1 += num - 1; // skip the rest in the for loop
break; // skip while sym2 loop
}
sym2++; // while sym2
}
}
}
}
 
 
// get imported library modules into modules2 buffer
void CLinker::readLibraryModules() {
uint32_t m1; // object file index
uint32_t m2; // library module index
uint32_t lib; // library index
uint32_t moduleOs; // offset to library module
 
// modules1 contains object files, libmodules contains index to library modules.
// we want to join these into the same buffer named modules2.
// The total number of object files and library modules is
uint32_t numModules = modules1.numEntries() + libmodules.numEntries();
// we cannot change the size of a metabuffer, so we will make a new
// bigger metabuffer and transfer everything from modules1 to modules2:
modules2.setSize(numModules);
for (m1 = 0; m1 < modules1.numEntries(); m1++) {
modules2[m1] << modules1[m1];
}
// now get the library modules
for (m2 = 0; m2 < libmodules.numEntries(); m2++) {
// library and offset
lib = libmodules[m2].library & 0x7FFFFFFF;
moduleOs = libmodules[m2].offset;
// put member into its own buffer
modules2[m1+m2].push(libraries[lib].buf() + moduleOs + (uint32_t)sizeof(SUNIXLibraryHeader),
libraries[lib].getMemberSize(moduleOs));
modules2[m1+m2].moduleName = cmd.fileNameBuffer.pushString(libraries[lib].getMemberName(moduleOs));
modules2[m1+m2].library = lib;
modules2[m1+m2].relinkable = libraries[lib].relinkable;
// put new module index into libmodules record
libmodules[m2].modul = m1 + m2;
}
}
 
// make list of all sections
void CLinker::makeSectionList() {
uint32_t m; // module index
uint32_t sh; // section header index
uint32_t sh_type; // section type
uint32_t secStringTableLen = 0; // length of section string table
const char * secStringTable = 0; // section string table in ELF module
const char * secName = 0; // section name
SLinkSection section; // section record
zeroAllMembers(section); // initialize
eventDataSize = 0; // total size of all event data sections
sections.push(section);
 
// loop through all modules to get all sections
for (m = 0; m < modules2.numEntries(); m++) {
if (modules2[m].dataSize() == 0) continue;
modules2[m].split(); // split module into components
secStringTable = (char*)modules2[m].stringBuffer.buf();
secStringTableLen = modules2[m].stringBuffer.dataSize();
for (sh = 0; sh < modules2[m].sectionHeaders.numEntries(); sh++) {
sh_type = modules2[m].sectionHeaders[sh].sh_type;
if (sh_type & (SHT_ALLOCATED | SHT_LIST)) {
section.sh_type = sh_type;
section.sh_flags = modules2[m].sectionHeaders[sh].sh_flags;
section.sh_size = modules2[m].sectionHeaders[sh].sh_size;
section.sh_align = modules2[m].sectionHeaders[sh].sh_align;
uint32_t namei = modules2[m].sectionHeaders[sh].sh_name;
if (namei >= secStringTableLen) secName = "?";
else secName = secStringTable + namei;
section.name = cmd.fileNameBuffer.pushString(secName);
section.sh_module = m;
section.sectioni = sh;
if (modules2[m].relinkable) section.sh_flags |= SHF_RELINK;
if (section.sh_flags & SHF_EVENT_HND) {
// check event data sections
eventDataSize += (uint32_t)section.sh_size;
// unsorted lists are preserved in executable file but not loaded into memory:
section.sh_type = SHT_LIST;
}
if (sh_type == SHT_COMDAT) {
communalSections.push(section); // communal section. sections with same name joined
}
else {
sections.push(section); // normal code, data, or bss section
}
}
}
}
// join communal sections with same name and add them to the sections list
joinCommunalSections();
 
// make dummy sections for unresolved weak external symbols
makeDummySections();
 
// sort the two section lists by the order in which it should occur in the executable
sortSections();
 
// add final index
for (uint32_t ix = 0; ix < sections.numEntries(); ix++) {
sections[ix].sectionx = ix + 1;
}
// copy the list
sections2.copy(sections);
// 'sections2' is sorted by module and section index for the purpose of finding back to the original
sections2.sort();
}
 
// sort sections in the order in which they should occur in the executable file
void CLinker::sortSections() {
uint32_t s; // section index
uint32_t order; // section sort order
uint32_t flags; // section flags
uint32_t type; // section type
 
/* The order is as listed below.
The base pointers are set to the limits where order changes from even to odd.
SHF_ALLOC:
0x02000002 SHT_ALLOCATED:
0x02000002 SHF_IP:
0x02101002 SHF_EVENT_HND
0x02202002 SHF_EXCEPTION_HND
0x02303002 SHF_DEBUG_INFO
0x02404002 SHF_COMMENT
0x02500002 SHF_WRITE
0x02600002 SHF_READ only !SHF_WRITE !SHF_EXEC (const)
0x02601002 SHF_AUTOGEN
0x02602002 SHF_RELINK
0x02603002 !SHF_RELINK !SHF_FIXED
0x02604002 SHF_FIXED
SHF_EXEC (code) (set ip_base)
0x02701003 SHF_FIXED !SHF_RELINK
0x02702003 !SHF_RELINK
0x02703003 SHF_RELINK
0x02704003 SHF_AUTOGEN
0x02800004 SHF_DATAP
SHT_PROGBITS (data)
0x02801004 SHF_RELINK
0x02802004 !SHF_FIXED
0x02803004 SHF_FIXED
SHT_NOBITS (bss) (set datap_base)
0x02806005 SHF_FIXED
0x02807005 !SHF_RELINK
0x02808005 SHF_RELINK
0x02809005 SHF_AUTOGEN
0x02A00006 SHF_THREADP
SHT_PROGBITS (data)
0x02A01006 SHF_RELINK
0x02A02006 !SHF_FIXED
0x02A03006 SHF_FIXED
SHT_NOBITS (bss) (set threadp_base)
0x02A06007 SHF_FIXED
0x02A07007 !SHF_RELINK
0x02A08007 SHF_RELINK
0x08000000 !SHT_ALLOCATED:
0x08100000 !SHF_ALLOC:
0x08110000 SHT_RELA
0x08120000 SHT_SYMTAB
0x08130000 SHT_STRTAB
0x08160000 other
*/
 
for (s = 0; s < sections.numEntries(); s++) {
flags = sections[s].sh_flags;
type = sections[s].sh_type;
if (flags & SHF_ALLOC) {
if (type & SHT_ALLOCATED) {
order = 0x02000000;
if (flags & SHF_IP) {
order = 0x02000002;
if (flags & SHF_EVENT_HND) order = 0x02101002;
else if (flags & SHF_EXCEPTION_HND) order = 0x02202002;
else if (flags & SHF_DEBUG_INFO) order = 0x02303002;
else if (flags & SHF_COMMENT) order = 0x02404002;
else if (flags & SHF_WRITE) order = 0x02500002;
else if ((flags & SHF_READ) && !(flags & SHF_EXEC)) {
order = 0x02600002;
if (flags & SHF_AUTOGEN) order = 0x02601002;
else if (flags & SHF_RELINK) order = 0x02602002;
else if (!(flags & SHF_FIXED)) order = 0x02603002;
else order = 0x02604002;
}
else if (flags & SHF_EXEC) {
if (!(flags & SHF_AUTOGEN)) {
if ((flags & SHF_FIXED) || !(flags & SHF_RELINK)) order = 0x02701003;
else if (!(flags & SHF_RELINK)) order = 0x02702003;
else order = 0x02703003;
}
else {
order = 0x02704003; // SHF_AUTOGEN
}
}
}
else if (flags & (SHF_DATAP | SHF_THREADP)) {
order = 0x02800004;
if (flags & SHF_THREADP) order = 0x02A00006;
if (type != SHT_NOBITS) {
if (flags & SHF_RELINK) order |= 0x1000;
else if (!(flags & SHF_FIXED)) order |= 0x2000;
else order |= 0x3000;
}
else { // SHT_NOBITS
order |= 1;
if (!(flags & SHF_AUTOGEN)) {
if (flags & SHF_FIXED) order |= 0x6000;
else if (!(flags & SHF_RELINK)) order |= 0x7000;
else order |= 0x8000;
}
else { // SHF_AUTOGEN
order |= 0x9000;
}
}
}
}
else { // !SHT_ALLOCATED
order = 0x08000000;
}
}
else { // !SHF_ALLOC
switch (type) {
case SHT_RELA:
order = 0x08110000; break;
case SHT_SYMTAB:
order = 0x08120000; break;
case SHT_STRTAB:
order = 0x08130000; break;
default:
order = 0x08160000; break;
}
}
sections[s].order = order;
}
sections.sort();
 
#if 0 // debug: list sections
for (s = 0; s < sections.numEntries(); s++) {
printf("\n* %8X %s", sections[s].order, cmd.getFilename(sections[s].name));
}
#endif
}
 
// join communal sections with same name
void CLinker::joinCommunalSections() {
uint32_t m; // module index
uint32_t s1 = 0, s2, s3, s4; // index into communalSections
uint32_t sym; // symbol index in module
uint32_t rel; // relocation index in module
const char * comname; // name of communal section
bool symbolsRemoved = false; // symbols in removed communal sections
 
communalSections.sort();
while (s1 < communalSections.numEntries()) {
comname = cmd.getFilename(communalSections[s1].name);
// find last entry with same name
s4 = s2 = s1;
while (s2 + 1 < communalSections.numEntries()
&& strcmp(comname, cmd.getFilename(communalSections[s2+1].name)) == 0) {
s2++;
}
 
// check that communal sections with same name have same size
bool differentSize = false;
for (s3 = s1+1; s3 <= s2; s3++) {
// a non-linkable communal section takes precedence
if (!(communalSections[s3].sh_flags & SHF_RELINK) && (communalSections[s4].sh_flags & SHF_RELINK)) {
s4 = s3;
}
else if (communalSections[s3].sh_size != communalSections[s1].sh_size) {
differentSize = true;
// find the biggest
if (communalSections[s3].sh_size > communalSections[s4].sh_size) s4 = s3;
}
}
if (differentSize) {
// make error message
CMemoryBuffer joinNames; // join section names for error message
joinNames.setSize(0);
m = communalSections[s1].sh_module;
const char * mname = cmd.getFilename(modules2[m].moduleName);
joinNames.push(mname, (uint32_t)strlen(mname));
for (s3 = s1 + 1; s3 <= s2; s3++) {
m = communalSections[s3].sh_module;
mname = cmd.getFilename(modules2[m].moduleName);
joinNames.push(", ", 2);
joinNames.push(mname, (uint32_t)strlen(mname));
}
err.submit(ERR_LINK_COMMUNAL, comname, (char*)joinNames.buf());
}
// check if there is any reference to this section. if not, purge it, except when debug level 2
bool keepSection = true;
if (cmd.debugOptions < 2) {
keepSection = false;
m = communalSections[s4].sh_module;
CELF * modul = &modules2[m];
// find symbols in this section
for (sym = 0; sym < modul->symbols.numEntries(); sym++) {
if (modul->symbols[sym].st_section == communalSections[s4].sectioni) {
const char * symname = (char*)modul->stringBuffer.buf() + modul->symbols[sym].st_name;
// search for this symbol name in symbolImports
SSymbolEntry symsearch;
symsearch.name = symbolNameBuffer.pushString(symname);
symsearch.st_bind = STB_IGNORE;
int32_t s = symbolImports.findFirst(symsearch);
if (s >= 0) {
keepSection = true; // there is a reference to this section. keep it
if (!(communalSections[s4].sh_flags & SHF_RELINK)) {
// communal section is not relinkable. Make the symbol non-weak
if (modul->symbols[sym].st_bind & STB_WEAK) {
modul->symbols[sym].st_bind = STB_GLOBAL;
}
}
break;
}
}
}
}
if (keepSection) {
// save one instance of the communal section
sections.push(communalSections[s4]);
}
// remove symbols and relocations from removed sections
for (s3 = s1; s3 <= s2; s3++) {
if (s3 != s4 || !keepSection) {
// this section is removed
m = communalSections[s3].sh_module;
CELF * modul = &modules2[m];
for (sym = 0; sym < modul->symbols.numEntries(); sym++) {
if (modul->symbols[sym].st_section == communalSections[s3].sectioni) {
const char * symname = (char*)modul->stringBuffer.buf() + modul->symbols[sym].st_name;
// search for this symbol name in symbolExports
SSymbolEntry symsearch;
symsearch.name = symbolNameBuffer.pushString(symname);
symsearch.st_bind = STB_IGNORE;
uint32_t firstMatch = 0;
uint32_t n = symbolExports.findAll(&firstMatch, symsearch);
// search through all symbols with this name
for (uint32_t i = firstMatch; i < firstMatch + n; i++) {
if (symbolExports[i].library == 0) {
if (symbolExports[i].member == m
&& symbolExports[i].sectioni == communalSections[s3].sectioni) {
// removed symbol found
symbolExports[i].name = 0;
symbolExports[i].st_bind = 0;
symbolsRemoved = true;
break;
}
}
else {
uint32_t m2 = findModule(symbolExports[i].library, symbolExports[i].member);
if (m2 == m && symbolExports[i].sectioni == communalSections[s4].sectioni) {
symbolExports[i].library = 0;
symbolExports[i].name = 0;
symbolExports[i].st_bind = 0;
symbolsRemoved = true;
break;
}
}
}
}
}
// search for relocations in removed section
for (rel = 0; rel < modul->relocations.numEntries(); rel++) {
if (modul->relocations[rel].r_section == communalSections[s3].sectioni) {
modul->relocations[rel].r_type = 0;
}
}
}
}
// continue with next communal name
s1 = s2 + 1;
}
if (symbolsRemoved) {
// entries have been removed from symbolExports. sort it again
symbolExports.sort();
}
}
 
// make dummy segments for event handler table and for unresolved weak externals
void CLinker::makeDummySections() {
SLinkSection section;
zeroAllMembers(section);
section.sh_type = SHT_PROGBITS;
section.sh_align = 3;
 
if (eventDataSize) {
section.sh_size = eventDataSize;
section.sh_flags = SHF_READ | SHF_IP | SHF_ALLOC | SHF_EVENT_HND | SHF_RELINK | SHF_AUTOGEN;
section.name = cmd.fileNameBuffer.pushString("eventhandlers_sorted");
section.sh_module = 0xFFFFFFF8;
sections.push(section);
}
 
// unresolved weak imports indicated by unresolvedWeak:
// 1: constant, 2: readonly ip data, 4: writeable datap data,
// 8: threadp, 0x10: function
if (unresolvedWeak & 2) {
section.sh_size = 8;
section.sh_flags = SHF_READ | SHF_IP | SHF_ALLOC | SHF_RELINK | SHF_AUTOGEN;
section.name = cmd.fileNameBuffer.pushString("zdummyconst");
section.sh_module = 0xFFFFFFF1;
sections.push(section);
}
if (unresolvedWeak & 4) {
section.sh_size = 8 * unresolvedWeakNum;
section.sh_flags = SHF_READ | SHF_WRITE | SHF_DATAP | SHF_ALLOC | SHF_RELINK | SHF_AUTOGEN;
section.name = cmd.fileNameBuffer.pushString("zdummydata");
section.sh_module = 0xFFFFFFF2;
sections.push(section);
}
if (unresolvedWeak & 8) {
section.sh_size = 8;
section.sh_flags = SHF_READ | SHF_WRITE | SHF_THREADP | SHF_ALLOC | SHF_RELINK | SHF_AUTOGEN;
section.name = cmd.fileNameBuffer.pushString("zdummythreaddata");
section.sh_module = 0xFFFFFFF3;
sections.push(section);
}
if (unresolvedWeak & 0x10) {
section.sh_size = 8;
section.sh_flags = SHF_EXEC | SHF_IP | SHF_ALLOC | SHF_RELINK | SHF_AUTOGEN;
section.name = cmd.fileNameBuffer.pushString("zdummyfunc");
section.sh_module = 0xFFFFFFF4;
sections.push(section);
}
}
 
// make sorted list of events
void CLinker::makeEventList() {
uint32_t sec; // section
 
// find event handler sections
for (sec = 0; sec < sections.numEntries(); sec++) {
if (sections[sec].sh_flags & SHF_EVENT_HND) {
uint32_t m = sections[sec].sh_module;
if (m < modules2.numEntries()) {
CELF * modul = &modules2[sections[sec].sh_module]; // find module
uint32_t offset = uint32_t(modul->sectionHeaders[sections[sec].sectioni].sh_offset);
uint32_t size = uint32_t(modul->sectionHeaders[sections[sec].sectioni].sh_size);
if (size & (sizeof(ElfFwcEvent)-1)) {
// event section size not divisible by event record size
err.submit(ERR_EVENT_SIZE, cmd.getFilename(modul->moduleName));
return;
}
// copy all event records
for (uint32_t index = 0; index < size; index += sizeof(ElfFwcEvent)) {
eventData.push(modul->dataBuffer.get<ElfFwcEvent>(offset + index));
}
}
}
}
// sort event list
eventData.sort();
}
 
 
// make program headers and assign addresses to sections
void CLinker::makeProgramHeaders() {
// Each program header can cover multiple sections with the same base pointer and
// the same read/write/execute permissions
uint32_t sec; // section index
uint32_t ph; // program header index
uint32_t lastFlags = 0; // p_flags of last program header
uint64_t offset = 0; // address relative to begin of section group
uint64_t * pBasePonter = 0; // pointer to base pointer
uint32_t secOrder; // indicates 'order' as defined in sortSections()
// secOrder & 0xF00000 indicates program header
// secOrder & 0x0E indicates base pointer
// Even values may have negative index relative to the base pointer,
// odd values have positive index relative to the base pointer
uint32_t lastSecOrder = 0; // secOrder of previous section
uint64_t align; // section alignment
uint8_t maxAlign = 0; // maximum alignment of all sections in group = (1 << maxAlign)
bool basePointerAssigned = false; // a base pointer has been assigned for this group
ElfFwcPhdr pHeader; // program header = segment definition
zeroAllMembers(pHeader); // initialize
 
// initialize pointer bases. may change later
ip_base = datap_base = threadp_base = 0;
event_table = event_table_num = 0;
 
// loop through sections to assign sections to program headers, and
// find the maximum alignment for each program header
for (sec = 0; sec < sections.numEntries(); sec++) {
// section order as defined by sortSections()
secOrder = sections[sec].order;
if (secOrder == 0 || !(sections[sec].sh_type & SHT_ALLOCATED)) {
// relocation tables, symbol tables, string tables, etc. need no program header.
// set address to zero
sections[sec].sh_addr = 0;
uint32_t mod = sections[sec].sh_module;
uint32_t seci = sections[sec].sectioni;
if (mod < modules2.numEntries() && seci < modules2[mod].sectionHeaders.numEntries()) {
// find section header
ElfFwcShdr & sectionHeader = modules2[mod].sectionHeaders[seci];
sectionHeader.sh_addr = 0;
}
continue; // don't put in program header
}
 
if ((secOrder & 0xF00000) != (lastSecOrder & 0xF00000)) {
// new program header. save last program header
if (pHeader.p_type != 0) {
// finished with previous section group
// check if alignment needs to be increased
if (maxAlign > pHeader.p_align) {
pHeader.p_align = maxAlign;
}
outFile.programHeaders.push(pHeader);
}
// start making new program header
zeroAllMembers(pHeader);
pHeader.p_type = PT_LOAD;
pHeader.p_flags = sections[sec].sh_flags;
maxAlign = sections[sec].sh_align;
if (((sections[sec].sh_flags ^ lastFlags) & SHF_PERMISSIONS) || (secOrder & 0xE) != (lastSecOrder & 0xE)) {
// different permissions or different base pointer. must align by at least 1 << MEMORY_MAP_ALIGN
if (maxAlign < MEMORY_MAP_ALIGN) maxAlign = MEMORY_MAP_ALIGN;
}
// use low 32 bits of p_paddr to store index into sections and
// high 32 bits to store number of sections
pHeader.p_paddr = sec;
}
lastSecOrder = secOrder;
lastFlags = sections[sec].sh_flags;
// find the section with the highest alignment
if (maxAlign < sections[sec].sh_align) maxAlign = sections[sec].sh_align;
// count sections covered by this header
pHeader.p_paddr += (uint64_t)1 << 32;
}
// finish last program header
if (pHeader.p_type != 0) {
// check if alignment needs to be increased
if (maxAlign > pHeader.p_align) {
pHeader.p_align = maxAlign;
}
// save last program header
outFile.programHeaders.push(pHeader);
}
 
// Divide program headers into groups of headers with the same base pointer and align the start of each
// group with the maximum alignment for the group
maxAlign = 0;
uint32_t last_flags = 0;
uint32_t group_ph = 0xFFFFFFFF; // first program header in group og program headers with same base pointer
 
// loop through program headers to find maximum alignment for each base pointer
for (ph = 0; ph < outFile.programHeaders.numEntries(); ph++) {
ElfFwcPhdr & rHeader = outFile.programHeaders[ph]; // reference to current program header
if ((rHeader.p_flags ^ last_flags) & SHF_BASEPOINTER) {
// new base pointer
if (group_ph != 0xFFFFFFFF) {
outFile.programHeaders[group_ph].p_align = maxAlign; // save maximum alignment to first program header in group
}
// start new header group
group_ph = ph;
maxAlign = 0;
last_flags = rHeader.p_flags;
}
if (rHeader.p_align > maxAlign) maxAlign = rHeader.p_align;
}
 
// loop through sections covered by each program header and assign addresses
lastFlags = 0; offset = 0;
for (ph = 0; ph < outFile.programHeaders.numEntries(); ph++) {
ElfFwcPhdr & rHeader = outFile.programHeaders[ph]; // reference to current program header
uint32_t fistSection = (uint32_t)rHeader.p_paddr;
uint32_t numSections = (uint32_t)(rHeader.p_paddr >> 32);
 
if ((rHeader.p_flags ^ lastFlags) & SHF_BASEPOINTER) {
// base pointer is different from last header. restart addressing
offset = 0; basePointerAssigned = false;
// get base pointer
switch (rHeader.p_flags & SHF_BASEPOINTER) {
case SHF_IP: // ip
pBasePonter = &ip_base;
break;
case SHF_DATAP: // datap
pBasePonter = &datap_base;
break;
case SHF_THREADP: // threadp
pBasePonter = &threadp_base;
break;
default:
pBasePonter = 0;
}
}
// align start of segment
align = (uint64_t)1 << rHeader.p_align;
offset = (offset + align - 1) & -(int64_t)align;
rHeader.p_vaddr = offset;
 
// find event_table
if ((outFile.programHeaders[ph].p_flags & SHF_EVENT_HND) && !(lastFlags & SHF_EVENT_HND)) {
event_table = (uint32_t)offset;
event_table_num = uint32_t(sections[fistSection].sh_size / sizeof(ElfFwcEvent));
}
 
// loop through sections covered by this program header
for (sec = fistSection; sec < fistSection + numSections; sec++) {
// get section start address
if (relinking
&& (sections[sec].sh_flags & SHF_FIXED)
&& basePointerAssigned) {
// this section belongs to the non-relinkable part of a relinkable file.
// the address must be the same as in the input file, relative to the base pointer
uint64_t offset2 = sections[sec].sh_addr + *pBasePonter;
if (offset2 - offset > MAX_ALIGN) {
err.submit(ERR_INDEX_OUT_OF_RANGE);
return;
}
offset = offset2;
}
else {
// align start of section
align = (uint64_t)1 << sections[sec].sh_align;
offset = (offset + align - 1) & -(int64_t)align;
}
// find base pointer
if (!basePointerAssigned && pBasePonter) {
if (relinking && (sections[sec].sh_flags & SHF_FIXED)) {
// this section is the first in a the non-relinkable part of a relinkable file.
// Place base pointer at the same position relative to this section as in the original
*pBasePonter = offset - sections[sec].sh_addr;
basePointerAssigned = true;
if (int64_t(*pBasePonter) < 0) {
err.submit(ERR_INDEX_OUT_OF_RANGE);
return;
}
}
else if (sections[sec].order & 1) {
// changing from const to executable or from data to bss. place base pointer here
offset = (offset + MEMORY_MAP_ALIGN - 1) & int64_t(-MEMORY_MAP_ALIGN);
*pBasePonter = offset;
basePointerAssigned = true;
}
else if (sec + 1 >= sections.numEntries() //fistSection + numSections
|| uint8_t(sections[sec+1].order) >> 1 != uint8_t(sections[sec].order) >> 1) {
// last section with this base pointer. place base pointer here
// (alternatively, place base pointer at the end of this section)
offset = (offset + MEMORY_MAP_ALIGN - 1) & int64_t(-MEMORY_MAP_ALIGN);
*pBasePonter = offset;
basePointerAssigned = true;
}
}
// save address
sections[sec].sh_addr = offset;
 
if (sections[sec].sh_module < 0xFFFFFFF0) {
// find section header
ElfFwcShdr & sectionHeader = modules2[sections[sec].sh_module].sectionHeaders[sections[sec].sectioni];
sectionHeader.sh_addr = offset;
offset += sectionHeader.sh_size;
}
else {
// dummy section for unresolved weak externals
switch (sections[sec].sh_module) {
case 0xFFFFFFF1:
dummyConst = (uint32_t)offset; break;
case 0xFFFFFFF2:
dummyData = (uint32_t)offset; break;
case 0xFFFFFFF3:
dummyThreadData = (uint32_t)offset; break;
case 0xFFFFFFF4:
dummyFunc = (uint32_t)offset; break;
}
offset += sections[sec].sh_size;
}
// align position in ELF file
offset = (offset + (1<<FILE_DATA_ALIGN)-1) & -(1<<FILE_DATA_ALIGN);
if ((rHeader.p_flags & SHF_READ) && ph+1 < outFile.programHeaders.numEntries()
&& !(outFile.programHeaders[ph+1].p_flags & SHF_READ)
&& rHeader.p_memsz <= rHeader.p_filesz) {
// readable section followed by non-readable section. Add empty space
offset += DATA_EXTRA_SPACE;
}
// update program header
rHeader.p_memsz = offset - rHeader.p_vaddr;
if (sections[sec].sh_type != SHT_NOBITS) {
rHeader.p_filesz = rHeader.p_memsz;
}
}
lastFlags = rHeader.p_flags;
}
 
// check if special symbols have been overridden
specialSymbolsOverride();
}
 
 
// check if automatic symbols have been overridden
void CLinker::specialSymbolsOverride() {
uint64_t addr;
bool basePointerChanged = false;
addr = findSymbolAddress("__ip_base");
if ((int64_t)addr >= 0) {
if (ip_base != addr) basePointerChanged = true;
ip_base = addr;
}
addr = findSymbolAddress("__datap_base");
if ((int64_t)addr >= 0) {
if (datap_base != addr) basePointerChanged = true;
datap_base = addr;
}
addr = findSymbolAddress("__threadp_base");
if ((int64_t)addr >= 0) {
if (threadp_base != addr) basePointerChanged = true;
threadp_base = addr;
}
if (relinking && basePointerChanged && modules2[0].sectionHeaders.numEntries()) {
// base pointer has been changed during relinking and there are fixed sections that
// may contain addresses relative to the old value of the base pointers
err.submit(ERR_RELINK_BASE_POINTER_MOD);
}
 
// find entry point
addr = findSymbolAddress("__entry_point");
if ((int64_t)addr >= 0) entry_point = addr;
else entry_point = ip_base;
}
 
// find a module from a record in symbolExports.
// the return value is an index into modules2
int32_t CLinker::findModule(uint32_t library, uint32_t memberos) {
if (library == 0) return memberos; // module not in a library
if (library == 0xFFFFFFFE) return -2; // special symbol, not in any module
SLibraryModule modu; // module is in a library
modu.library = library;
modu.offset = memberos;
int32_t i = libmodules.findFirst(modu);
if (i >= 0) return libmodules[i].modul;
return -1;
}
 
 
// put values into all cross references
void CLinker::relocate() {
uint32_t modu; // module index
uint32_t r; // relocation loop counter
ElfFwcReloc * reloc; // relocation record
uint32_t sourcePos; // relocation source position in file
ElfFwcSym * targetSym; // target symbol record
ElfFwcSym * externTargetSym; // external target symbol record
ElfFwcSym * refSym; // reference symbol record
uint64_t targetAddress; // address of target symbol
uint64_t referenceAddress; // address of reference symbol
int64_t value; // value of relocation
uint32_t targetModule; // module containing target symbol
uint32_t refsymModule; // module containing reference symbol
SReloc2 rel2; // relocation record for executable file
bool relink; // copy relocation to relinkable executable file
 
// loop through all modules to get all relocation records
for (modu = 0; modu < modules2.numEntries(); modu++) {
if (modules2[modu].dataSize() == 0) continue;
relink = modules2[modu].relinkable;
for (r = 0; r < modules2[modu].relocations.numEntries(); r++) {
// loop through relocations
reloc = &modules2[modu].relocations[r];
if (reloc->r_type == 0) continue; // removed relocation
// find source address
if (reloc->r_section > modules2[modu].nSections) {
err.submit(ERR_ELF_INDEX_RANGE); continue;
}
// source address in executable file
// uint64_t sourceAddr = modules2[modu].sectionHeaders[reloc->r_section].sh_addr + reloc->r_offset;
// source address in local module. This is where the binary data are currently stored
sourcePos = uint32_t(modules2[modu].sectionHeaders[reloc->r_section].sh_offset + reloc->r_offset);
if (sourcePos >= modules2[modu].dataBuffer.dataSize()) {
err.submit(ERR_ELF_INDEX_RANGE); continue;
}
// find target symbol
targetSym = &modules2[modu].symbols[reloc->r_sym];
externTargetSym = findSymbolAddress(&targetAddress, &targetModule, targetSym, modu);
if (externTargetSym == 0) {
err.submit(ERR_ELF_INDEX_RANGE); continue;
}
// check if target symbol is in relinkable section
if (externTargetSym->st_other & STV_RELINK) relink = true;
if (relink) {
// copy symbol records to executable file if necessary
if (targetSym->st_section || (targetSym->st_bind & STB_WEAK)) {
targetSym->st_bind |= STB_EXE;
}
}
 
// check register use
checkRegisterUse(targetSym, externTargetSym, targetModule);
 
// find reference symbol
if (reloc->r_refsym && (reloc->r_type & R_FORW_RELTYPEMASK) == R_FORW_REFP) {
refSym = &modules2[modu].symbols[reloc->r_refsym];
refSym = findSymbolAddress(&referenceAddress, &refsymModule, refSym, modu);
if (refSym->st_other & STV_RELINK) relink = true;
}
else {
refSym = 0;
referenceAddress = 0;
refsymModule = 0;
}
value = int64_t(targetAddress - referenceAddress);
 
// select relocation type
switch (reloc->r_type >> 16 & 0xFF) {
case R_FORW_ABS >> 16: // absolute symbol or absolute address
if (externTargetSym->st_type != STT_CONSTANT && externTargetSym->st_type != 0) {
// this is an absolute address to insert at load time. the code is not position-independent
// char * nm = (char*)modules2[modu].stringBuffer.buf() + targetSym->st_name;
reloc->r_type |= R_FORW_LOADTIME;
fileHeader.e_flags |= EF_RELOCATE | EF_POSITION_DEPENDENT;
}
break;
case R_FORW_SELFREL >> 16:
value = int64_t(targetAddress - reloc->r_offset - modules2[modu].sectionHeaders[reloc->r_section].sh_addr);
if ((modules2[modu].sectionHeaders[reloc->r_section].sh_flags
^ externTargetSym->st_other) & SHF_BASEPOINTER) {
// different base pointers
DIFFERENTBASEPOINTERS:
err.submit(ERR_LINK_DIFFERENT_BASE,
cmd.getFilename(modules2[modu].moduleName),
(char*)modules2[modu].stringBuffer.buf() + externTargetSym->st_name,
cmd.getFilename(modules2[targetModule].moduleName));
}
break;
case R_FORW_IP_BASE >> 16:
value = int64_t(targetAddress - ip_base);
if (!(externTargetSym->st_other & STV_IP)) goto DIFFERENTBASEPOINTERS;
break;
case R_FORW_DATAP >> 16:
value = int64_t(targetAddress - datap_base);
if (!(externTargetSym->st_other & STV_DATAP)) goto DIFFERENTBASEPOINTERS;
break;
case R_FORW_THREADP >> 16:
if (!(externTargetSym->st_other & STV_THREADP)) goto DIFFERENTBASEPOINTERS;
break;
case R_FORW_REFP >> 16:
if (refSym == 0 || ((externTargetSym->st_other ^ refSym->st_other) & SHF_BASEPOINTER)) {
goto DIFFERENTBASEPOINTERS;
}
break;
case R_FORW_SYSFUNC:
case R_FORW_SYSMODUL:
case R_FORW_SYSCALL:
// system function ID inserted at load time
reloc->r_type |= R_FORW_LOADTIME;
fileHeader.e_flags |= EF_RELOCATE;
break;
}
// add addend (sign extended)
value += reloc->r_addend;
// scale
uint32_t scale = reloc->r_type & R_FORW_RELSCALEMASK;
// check if divisible by scale
if (value & ((1 << scale) - 1)) {
// misaligned target. scaling of reference failed
err.submit(ERR_LINK_MISALIGNED_TARGET,
cmd.getFilename(modules2[modu].moduleName),
(char*)modules2[modu].stringBuffer.buf() + externTargetSym->st_name,
cmd.getFilename(modules2[targetModule].moduleName));
}
value >>= scale;
 
// check if overflow and insert value
switch ((reloc->r_type >> 8) & 0xFF) {
case R_FORW_8 >> 8:
modules2[modu].dataBuffer.get<int8_t>((uint32_t)sourcePos) = (int8_t)value;
if (value > 0x7F || value < -0x80) {
RELOCATIONOVERFLOW:
err.submit(ERR_LINK_OVERFLOW,
cmd.getFilename(modules2[modu].moduleName),
(char*)modules2[modu].stringBuffer.buf() + externTargetSym->st_name,
cmd.getFilename(modules2[targetModule].moduleName));
}
break;
case R_FORW_16 >> 8:
modules2[modu].dataBuffer.get<int16_t>((uint32_t)sourcePos) = (int16_t)value;
if (value > 0x7FFF || value < -0x8000) goto RELOCATIONOVERFLOW;
break;
case R_FORW_24 >> 8:
modules2[modu].dataBuffer.get<int16_t>((uint32_t)sourcePos) = (int16_t)value;
modules2[modu].dataBuffer.get<int8_t>((uint32_t)sourcePos + 2) = (int8_t)(value >> 16);
if (value > 0x7FFFFF || value < -0x800000) goto RELOCATIONOVERFLOW;
break;
case R_FORW_32 >> 8:
modules2[modu].dataBuffer.get<int32_t>((uint32_t)sourcePos) = (int32_t)value;
if (value > 0x7FFFFFFF || value < -((int64_t)1 << 31)) goto RELOCATIONOVERFLOW;
break;
case R_FORW_32LO >> 8:
modules2[modu].dataBuffer.get<int16_t>((uint32_t)sourcePos) = (int16_t)value;
if (value > 0x7FFFFFFF || value < -((int64_t)1 << 31)) goto RELOCATIONOVERFLOW;
break;
case R_FORW_32HI >> 8:
if (value > 0x7FFFFFFF || value < -((int64_t)1 << 31)) goto RELOCATIONOVERFLOW;
modules2[modu].dataBuffer.get<int16_t>((uint32_t)sourcePos) = (int16_t)(value >> 16);
if (value > 0x7FFFFFFF || value < -((int64_t)1 << 31)) goto RELOCATIONOVERFLOW;
break;
case R_FORW_64 >> 8:
modules2[modu].dataBuffer.get<int64_t>((uint32_t)sourcePos) = value;
break;
case R_FORW_64LO >> 8:
modules2[modu].dataBuffer.get<int32_t>((uint32_t)sourcePos) = (int32_t)value;
break;
case R_FORW_64HI >> 8:
modules2[modu].dataBuffer.get<int32_t>((uint32_t)sourcePos) = (int32_t)(value >> 32);
break;
}
// mark reference to unresolved and autogenerated symbols for copy to executable
if (relinkable) {
if (externTargetSym->st_section == 0 && (externTargetSym->st_bind & STB_WEAK)) relink = true;
if (refSym && refSym->st_section == 0 && (refSym->st_bind & STB_WEAK)) relink = true;
if (externTargetSym->st_other & STV_AUTOGEN) relink = true;
if (refSym && refSym->st_other & STV_AUTOGEN) relink = true;
}
// copy symbols and relocation record to executable file if target symbol or reference symbol are in relinkable sections
if (relink || (reloc->r_type & R_FORW_LOADTIME)) {
externTargetSym->st_bind |= STB_EXE;
if (refSym) refSym->st_bind |= STB_EXE;
memcpy(&rel2, reloc, sizeof(ElfFwcReloc));
rel2.modul = modu;
rel2.symLocal = (targetModule == modu) // symbol is local
|| ((targetSym->st_bind & STB_EXE) && targetSym->st_section == 0); // keep local record for weak external so that it can be replaced by relinking
rel2.refSymLocal = (refsymModule == modu);
relocations2.push(rel2);
}
}
}
}
 
// Check if external function call has compatible register use
void CLinker::checkRegisterUse(ElfFwcSym * sym1, ElfFwcSym * sym2, uint32_t modul) {
if ((sym1->st_other | sym1->st_other) & STV_REGUSE) {
// register use specified for source or target or both
uint32_t tregusea1 = sym1->st_reguse1;
uint32_t tregusea2 = sym1->st_reguse2;
uint32_t treguseb1 = sym2->st_reguse1;
uint32_t treguseb2 = sym2->st_reguse2;
if (!(sym1->st_other & STV_REGUSE)) {
tregusea1 = tregusea2 = 0x0000FFFF; // register use not specified for source. assume default
}
if (sym1 == sym2 && sym1->st_section == 0 && (sym1->st_bind & STB_WEAK)) {
// unresolved weak. will set r0 = 0 and v0 = 0
treguseb1 = unresolvedReguse1;
treguseb2 = unresolvedReguse2;
}
else if (!(sym2->st_other & STV_REGUSE)) {
// register use not specified for external target. assume default
treguseb1 = treguseb2 = 0x0000FFFF;
}
uint32_t tregusem1 = treguseb1 & ~tregusea1; // registers in target and not in source
uint32_t tregusem2 = treguseb2 & ~tregusea2;
if (tregusem1 | tregusem2) {
// mismatched register use
const char * symname = modules2[modul].stringBuffer.getString(sym2->st_name);
char text[30];
sprintf(text, "0x%X, 0x%X", tregusem1, tregusem2);
err.submit(ERR_LINK_REGUSE, cmd.getFilename(modules2[modul].moduleName), symname,text);
// avoid reporting multiple times if there are multiple references from a module to the same symbol
sym1->st_reguse1 = treguseb1;
sym1->st_reguse2 = treguseb2;
}
}
}
 
// find a symbol and its address
// the return value is a pointer to a remote symbol record. The address is returned in 'a'
ElfFwcSym * CLinker::findSymbolAddress(uint64_t * a, uint32_t * targetMod, ElfFwcSym * sym, uint32_t modul) {
if (targetMod) *targetMod = modul;
if (sym->st_section && (sym->st_bind & ~STB_EXE) != STB_WEAK2) {
// target is in same module
if (sym->st_type == STT_CONSTANT) {
// absolute symbol
*a = sym->st_value;
}
else if (sym->st_section >= modules2[modul].nSections) {
err.submit(ERR_ELF_INDEX_RANGE); return sym;
}
else { // section address + offset into section
// check if section is included in exe file.
// This will fail if there is a reference to a non-weak symbol in a replaced local communal section
SLinkSection2 secSearch;
secSearch.sh_module = modul;
secSearch.sectioni = sym->st_section;
int32_t x = sections2.findFirst(secSearch);
if (x < 0) {
const char * symname = (char*)modules2[modul].stringBuffer.buf() + sym->st_name;
err.submit(ERR_LINK_UNRESOLVED, symname, "(relocation)");
return sym;
}
*a = modules2[modul].sectionHeaders[sym->st_section].sh_addr + sym->st_value;
}
return sym;
}
else {
// target is external. find it in symbolExports
SSymbolEntry symSearch; // record for searching for symbol
zeroAllMembers(symSearch); // initialize
if (sym->st_name > modules2[modul].stringBuffer.dataSize()) {
err.submit(ERR_ELF_INDEX_RANGE); return sym;
}
const char * symname = (char*)modules2[modul].stringBuffer.buf() + sym->st_name;
symSearch.name = symbolNameBuffer.pushString(symname);
symSearch.st_bind = STB_IGNORE; // find both strong and weak symbols
uint32_t firstMatch = 0;
uint32_t numMatch = symbolExports.findAll(&firstMatch, symSearch);
if (numMatch == 0) {
// symbol name not found
if (!(sym->st_bind & STB_WEAK)) {
sym->st_bind = STB_UNRESOLVED; // not weak. mark as unresolved
if (sym->st_type == STT_FUNC) sym->st_other |= SHF_EXEC;
}
// give it a dummy
*targetMod = 0;
switch (sym->st_other & (SHF_BASEPOINTER | SHF_EXEC)) {
case 0: // constant
*a = 0; break;
case STV_IP: // read-only data
*a = dummyConst; break;
case STV_DATAP: // writeable data. Make one address for each unresolved reference
*a = dummyData + (--unresolvedWeakNum) * 8;
break;
case STV_THREADP: // thread-local. this is rare
*a = dummyThreadData; break;
case STV_IP | STV_EXEC: // unresolved function
*a = dummyFunc; break;
}
return sym;
}
// one or more matching symbols found
int32_t targetModule = findModule(symbolExports[firstMatch].library, symbolExports[firstMatch].member);
if (targetModule == -2) {
// special symbol
switch (symbolExports[firstMatch].symindex) {
case 1:
*a = ip_base; break;
case 2:
*a = datap_base; break;
case 3:
*a = threadp_base; break;
case 4:
*a = event_table; break;
case 5:
*a = event_table_num; break;
default:
err.submit(ERR_LINK_UNRESOLVED, symname, "relocation");
}
sym->st_other |= STV_AUTOGEN; // symbol is autogenerated
return sym;
}
if (targetMod) *targetMod = targetModule;
if (targetModule < 0) {
// unexpected error
err.submit(ERR_LINK_UNRESOLVED, symname, "relocation");
return sym;
}
// find external target symbol
ElfFwcSym * targetSym = &modules2[targetModule].symbols[symbolExports[firstMatch].symindex];
if (modules2[targetModule].relinkable) {
targetSym->st_other |= STV_RELINK;
}
if (targetSym->st_type == STT_CONSTANT) {
// absolute symbol
*a = targetSym->st_value;
}
else if (targetSym->st_section >= modules2[targetModule].nSections) {
err.submit(ERR_ELF_INDEX_RANGE); return sym;
}
else { // section address + offset into section
// check if target section is included in exe file. This will fail only if there is a reference to a non-weak symbol in a replaced local communal section
SLinkSection2 secSearch;
secSearch.sh_module = targetModule;
secSearch.sectioni = targetSym->st_section;
int32_t x = sections2.findFirst(secSearch);
if (x < 0) {
const char * symname = (char*)modules2[modul].stringBuffer.buf() + sym->st_name;
err.submit(ERR_LINK_UNRESOLVED, symname, "(removed)");
return sym;
}
*a = modules2[targetModule].sectionHeaders[targetSym->st_section].sh_addr + targetSym->st_value;
}
return targetSym;
}
}
 
// find the final address of a symbol from its name
uint64_t CLinker::findSymbolAddress(const char * name) {
SSymbolEntry symSearch; // record for symbol search
int32_t symi; // symbol index
int32_t modul; // module containing symbol
ElfFwcSym * sym; // pointer to symbol record
uint64_t addr = 0xFFFFFFFFFFFFFFFF; // return value
symSearch.name = symbolNameBuffer.pushString(name);
symSearch.st_bind = STB_GLOBAL; // search for strong symbols only
symi = symbolExports.findFirst(symSearch);
if (symi >= 0) { // strong symbol found
modul = findModule(symbolExports[symi].library, symbolExports[symi].member);
if (modul >= 0) {
sym = &modules2[modul].symbols[symbolExports[symi].symindex];
findSymbolAddress(&addr, 0, sym, modul);
}
}
return addr;
}
 
// copy sections to output file
void CLinker::copySections() {
ElfFwcShdr header; // section header
zeroAllMembers(header); // initialize
uint32_t s; // section index
CELF * modul; // module containing section
uint32_t sectionx = 0; // section index in executable file
uint32_t progheadi = 0; // program header index
uint32_t lastprogheadi = 0xFFFFFFFF; // program header index of previous section
CMemoryBuffer dummyBuffer; // buffer for dummy symbols
CMemoryBuffer * dataBuf; // pointer to data buffer
uint64_t dummyValue; // value of unresolved weak external symbols
uint32_t lastFlags = 0; // previous section flags
uint8_t type, lastType = 0; // section type
uint32_t pHfistSection = 0; // first section covered by program header
uint32_t pHlastSection = 0; // last section covered by program header
uint32_t pHnumSections = 0; // number of sections covered by program header
ElfFwcPhdr * pPHead = 0; // pointer to program header
 
// find program header
if (outFile.programHeaders.numEntries()) {
pPHead = &outFile.programHeaders[progheadi];
pHfistSection = (uint32_t)pPHead->p_paddr;
pHnumSections = (uint32_t)(pPHead->p_paddr >> 32);
}
 
// loop through sections
for (s = 0; s < sections.numEntries(); s++) {
// make section header
header.sh_type = sections[s].sh_type;
if (header.sh_type == 0) continue;
header.sh_name = sections[s].name;
header.sh_flags = sections[s].sh_flags;
header.sh_size = sections[s].sh_size;
header.sh_align = sections[s].sh_align;
header.sh_module = sections[s].sh_module;
if (header.sh_module < modules2.numEntries()) {
modul = &modules2[sections[s].sh_module]; // find module
header.sh_library = modul->library;
header.sh_offset = modul->sectionHeaders[sections[s].sectioni].sh_offset;
header.sh_addr = modul->sectionHeaders[sections[s].sectioni].sh_addr;
dataBuf = &modul->dataBuffer;
}
else {
header.sh_library = 0;
// make section for dummy symbol
switch (sections[s].sh_module) {
case 0xFFFFFFF1: default: // read only data
dummyValue = 0;
header.sh_offset = dummyBuffer.push(&dummyValue, 8);
header.sh_addr = dummyConst;
break;
case 0xFFFFFFF2: // writeable data
dummyValue = 0;
header.sh_offset = dummyBuffer.dataSize();
header.sh_addr = dummyData;
for (uint32_t i = 0; i < unresolvedWeakNum; i++) dummyBuffer.push(&dummyValue, 8);
break;
case 0xFFFFFFF3: // thread-local data
dummyValue = 0;
header.sh_offset = dummyBuffer.push(&dummyValue, 8);
header.sh_addr = dummyThreadData;
break;
case 0xFFFFFFF4: // unresolved weak function. return zero
header.sh_addr = dummyFunc;
header.sh_offset = dummyBuffer.dataSize();
for (uint32_t i = 0; i < unresolvedFunctionN; i++) {
dummyBuffer.push(&unresolvedFunction[i], 4);
}
break;
case 0xFFFFFFF8: // event list
header.sh_offset = dummyBuffer.push(eventData.buf(), eventData.dataSize());
break;
}
dataBuf = &dummyBuffer;
}
// find correcponding program header, if any
while (s >= pHfistSection + pHnumSections && progheadi+1 < outFile.programHeaders.numEntries()) {
progheadi++;
pPHead = &outFile.programHeaders[progheadi];
pHfistSection = (uint32_t)pPHead->p_paddr;
pHnumSections = (uint32_t)(pPHead->p_paddr >> 32);
}
// is this section covered by a program header?
bool hasProgHead = s >= pHfistSection && s < pHfistSection + pHnumSections;
 
if (hasProgHead && progheadi == lastprogheadi && s > 0 && sections[s].sh_type != SHT_NOBITS) {
// this section is covered by same program header as last section
// insert any necessary filler
uint64_t fill = sections[s].sh_addr - (sections[s-1].sh_addr + sections[s-1].sh_size);
if (fill > MAX_ALIGN) err.submit(ERR_LINK_OVERFLOW, "","","");
if (fill > 0) {
// insert alignment filler in dataBuffer
outFile.insertFiller(fill);
}
}
type = header.sh_type;
if (type == SHT_COMDAT) type = SHT_PROGBITS; // communal and normal data can be joined together
 
// add section to outFile
if (hasProgHead
&& progheadi == lastprogheadi
&& type == lastType
&& !cmd.debugOptions
&& !(header.sh_flags & SHF_RELINK)
&& !(lastFlags & SHF_RELINK)
&& sections[s].sh_module < 0xFFFFFFF0) {
outFile.extendSection(header, *dataBuf);
}
else {
sectionx = outFile.addSection(header, cmd.fileNameBuffer, *dataBuf);
}
// remember new section index
sections[s].sectionx = sectionx;
lastprogheadi = progheadi;
lastType = type;
lastFlags = header.sh_flags;
 
#if 0 // testing only: list sections
ElfFwcShdr header3 = outFile.sectionHeaders[sectionx];
printf("\n%2i %X os=%X, sz=%X %s", outFile.sectionHeaders.numEntries(), header3.sh_type, header3.sh_offset, header3.sh_size, cmd.getFilename(header.sh_name));
#endif
}
 
// update section indexes in segment headers.
// indexes may have changed if some sections are joined together.
// p_paddr contains first section index and number of sections
for (uint32_t ph = 0; ph < outFile.programHeaders.numEntries(); ph++) {
pHfistSection = (uint32_t)outFile.programHeaders[ph].p_paddr;
pHnumSections = (uint32_t)(outFile.programHeaders[ph].p_paddr >> 32);
pHlastSection = pHfistSection + pHnumSections - 1;
if (pHlastSection < sections.numEntries()) {
uint32_t sx1 = sections[pHfistSection].sectionx; // first new section index
uint32_t sx2 = sections[pHlastSection].sectionx; // last new section index
uint32_t numsx = sx2 - sx1 + 1; // number of new sections
outFile.programHeaders[ph].p_paddr = sx1 | (uint64_t)numsx << 32;
}
}
 
// sections list has been modified. update sections2
sections2.copy(sections);
sections2.sort();
 
// make lists of module names and library names
CDynamicArray<uint32_t> moduleNames, libraryNames;
moduleNames.setNum(modules2.numEntries());
for (uint32_t m = 0; m < modules2.numEntries(); m++) {
moduleNames[m] = modules2[m].moduleName;
}
libraryNames.setNum(libraries.numEntries());
for (uint32_t lib = 0; lib < libraries.numEntries(); lib++) {
libraryNames[lib] = libraries[lib].libraryName;
}
 
// copy module names and library names to relinkable sections
outFile.addModuleNames(moduleNames, libraryNames);
}
 
// copy symbols to output file
void CLinker::copySymbols() {
uint32_t s; // symbol index
ElfFwcSym sym; // symbol record
uint32_t modul; // module containing symbol
SSymbolXref2 xref; // symbol cross reference record
SLinkSection2 searchSection; // record to search for section
char const * name; // symbol name
int32_t sx; // section index in sections2
char text[12]; // temporary text
CDynamicArray<SSymbolXref2> xreflist; // list of cross reference records, sorted by name
// make symbol number 0 empty
zeroAllMembers(sym);
outFile.addSymbol(sym, cmd.fileNameBuffer);
 
for (s = 0; s < symbolExports.numEntries(); s++) {
// skip weak public symbols if overridden and not relinkable
while (s+1 < symbolExports.numEntries() && symbolExports[s] == symbolExports[s+1]) {
// next symbol has same name
modul = findModule(symbolExports[s].library, symbolExports[s].member);
if (modules2[modul].relinkable) break; // relinkable. preserve both symbols
if (symbolExports[s+1].st_bind & STB_WEAK) {
modul = findModule(symbolExports[s+1].library, symbolExports[s+1].member);
modules2[modul].symbols[symbolExports[s+1].symindex].st_bind |= STB_IGNORE;
}
s++;
}
// if (symbolExports[s].library == 0xFFFFFFFE)
// The special symbols __ip_base, etc are not copied to the executable file.
// If we want them then we need to find the corresponding sections
}
 
// loop through all modules to get all symbols
for (modul = 0; modul < modules2.numEntries(); modul++) {
for (s = 0; s < modules2[modul].symbols.numEntries(); s++) {
sym = modules2[modul].symbols[s];
if (sym.st_section || (sym.st_bind & STB_EXE)) {
if ((sym.st_bind & (STB_EXE | STB_IGNORE)) == STB_EXE
|| ((sym.st_bind & (STB_GLOBAL | STB_WEAK)))
|| (cmd.debugOptions && sym.st_bind != STB_IGNORE)) {
name = (char*)modules2[modul].stringBuffer.buf() + modules2[modul].symbols[s].st_name;
xref.modul = modul;
xref.name = symbolNameBuffer.pushString(name);
xref.symi = s;
xref.symx = 0;
xref.isPublic = sym.st_section != 0;
xref.isWeak = (sym.st_bind & STB_WEAK) != 0;
xreflist.push(xref);
}
}
}
}
// sort by name
xreflist.sort();
bool changed = false;
// remove any $$number and subsequent text from all symbol names
for (s = 0; s < xreflist.numEntries(); s++) {
char * name1 = (char*)symbolNameBuffer.buf() + xreflist[s].name;
char * p = strchr(name1, '$');
if (p && p[1] == '$' && p[2] >= '0' && p[2] <= '9') {
*p = 0;
changed = true;
}
}
// sort again
if (changed) xreflist.sort();
 
// search for duplicate names
for (s = 0; s < xreflist.numEntries(); s++) {
uint32_t num = 0;
name = symbolNameBuffer.getString(xreflist[s].name);
if (xreflist[s].isPublic && !xreflist[s].isWeak) {
// local or public non-weak symbol. check if duplicate names
while (s+1 < xreflist.numEntries() && !(xreflist[s] < xreflist[s+1])) {
// next symbol has same name
s++;
if (xreflist[s].isPublic && !xreflist[s].isWeak) {
// this symbol is local or public and non-weak. there is a name clash
// change duplicate name to name$$number
xreflist[s].name = symbolNameBuffer.push(name, (uint32_t)strlen(name));
sprintf(text, "$$%u", ++num);
symbolNameBuffer.pushString(text);
const char * name2 = symbolNameBuffer.getString(xreflist[s].name);
// also change name of original symbol
SSymbolXref2 & x2 = xreflist[s];
ElfFwcSym & s2 = modules2[x2.modul].symbols[x2.symi];
s2.st_name = modules2[x2.modul].stringBuffer.pushString(name2);
}
}
}
}
// sort cross references by module
symbolXref << xreflist;
symbolXref.sort();
 
// copy symbols to outFile
for (s = 0; s < symbolXref.numEntries(); s++) {
modul = symbolXref[s].modul;
sym = modules2[modul].symbols[symbolXref[s].symi];
if (sym.st_section != 0) {
// translate local section index to final section index
searchSection.sh_module = modul;
searchSection.sectioni = sym.st_section;
sx = sections2.findFirst(searchSection);
if (sx < 0) {
continue; // symbol is in a discarded communal section. drop it
}
// adjust address
uint32_t newsection = sections2[sx].sectionx;
sym.st_value += sections2[sx].sh_addr - outFile.sectionHeaders[newsection].sh_addr;
sym.st_section = newsection;
}
sym.st_bind &= ~ STB_EXE;
symbolXref[s].symx = outFile.addSymbol(sym, modules2[modul].stringBuffer);
}
// make records for unresolved weak symbols
if (relinkable) {
zeroAllMembers(sym);
for (s = 0; s < symbolImports.numEntries(); s++) {
if ((symbolImports[s].status & 5) && (symbolImports[s].st_bind & STB_WEAK)) {
// unresolved weak. make a symbol record
sym.st_name = symbolImports[s].name;
sym.st_type = symbolImports[s].st_type;
sym.st_bind = symbolImports[s].st_bind;
sym.st_other = symbolImports[s].st_other;
// skip any additional unresolved symbols with same name
while (s+1 < symbolImports.numEntries() && symbolImports[s] == symbolImports[s+1]) s++;
// put record in output file
xref.symx = outFile.addSymbol(sym, symbolNameBuffer);
xref.name = sym.st_name;
xref.modul = symbolImports[s].library;
xref.symi = symbolImports[s].symindex;
// put new index into list of unresolved weak symbols
unresWeakSym.push(xref); // this list will be sorted by name because symbolImports is sorted by name
}
}
}
}
 
// copy relocation records to output file if needed
void CLinker::copyRelocations() {
uint32_t r; // relocation index
int32_t s; // symbol index
SReloc2 rel2; // extended relocation record
SSymbolXref symx; // record for searching for symbol in symbolXref
CDynamicArray<SReloc2> relocations3; // extended relocation records. load-time relocations first
relocations3.setSize(relocations2.dataSize());
 
// get load-time relocations first
for (r = 0; r < relocations2.numEntries(); r++) {
if (relocations2[r].r_type & R_FORW_LOADTIME) {
relocations3.push(relocations2[r]);
}
}
// get remaining relocations, used only for relinking
for (r = 0; r < relocations2.numEntries(); r++) {
if (!(relocations2[r].r_type & R_FORW_LOADTIME)) {
relocations3.push(relocations2[r]);
}
}
 
// relocations3 contains list of relocations that need to be copied to executable file
for (r = 0; r < relocations3.numEntries(); r++) {
rel2 = relocations3[r];
if (rel2.r_type == 0) continue; // removed
if (rel2.modul >= modules2.numEntries()) {
err.submit(ERR_ELF_INDEX_RANGE); continue;
}
// translate section index
SLinkSection2 secSearch;
secSearch.sh_module = rel2.modul;
secSearch.sectioni = rel2.r_section;
int32_t x = sections2.findFirst(secSearch);
if (x < 0) continue; // section not found. ignore
rel2.r_section = sections2[x].sectionx;
// adjust offset
rel2.r_offset += sections2[x].sh_addr - outFile.sectionHeaders[rel2.r_section].sh_addr;
 
// translate symbol index
if (rel2.symLocal) {
// symbol is local. reference by ID
symx.modul = rel2.modul;
symx.symi = rel2.r_sym;
s = symbolXref.findFirst(symx);
if (s < 0) {
// unresolved weak
rel2.r_sym = resolveRelocationTarget(rel2.modul, rel2.r_sym);
}
else rel2.r_sym = symbolXref[s].symx;
}
else {
// symbol is remote. search by name
rel2.r_sym = resolveRelocationTarget(rel2.modul, rel2.r_sym);
}
 
// translate reference symbol index
if (rel2.r_refsym) {
if (rel2.refSymLocal) {
// reference symbol is local. reference by ID
symx.modul = rel2.modul;
symx.symi = rel2.r_refsym;
s = symbolXref.findFirst(symx);
if (s < 0) {
rel2.r_refsym = resolveRelocationTarget(rel2.modul, rel2.r_refsym);
}
else rel2.r_refsym = symbolXref[s].symx;
}
else {
// reference symbol is remote. search by name
rel2.r_refsym = resolveRelocationTarget(rel2.modul, rel2.r_refsym);
}
}
// put relocation in outFile
outFile.addRelocation(rel2);
}
}
 
// resolve relocation target for executable file record
uint32_t CLinker::resolveRelocationTarget(uint32_t modul, uint32_t symi) {
CELF * modulp; // pointer to module
const char * symname; // symbol name
int32_t ie; // index into symbolExports
int32_t iu; // index into unresWeakSym
int32_t is; // index into symbolXref
uint32_t modt; // target module
SSymbolEntry syms; // record for searching for symbol in symbolExports
SSymbolXref2 symu; // record for searching for symbol in unresWeakSym
SSymbolXref symx; // record for searching for symbol in symbolXref
 
modulp = &modules2[modul]; // module
// search by name
if (symi >= modulp->symbols.numEntries()) {
err.submit(ERR_ELF_INDEX_RANGE); return 0;
}
symname = (char*)modulp->stringBuffer.buf() + modulp->symbols[symi].st_name;
syms.name = symbolNameBuffer.pushString(symname);
syms.st_bind = STB_IGNORE; // find both strong and weak symbols
ie = symbolExports.findFirst(syms);
if (ie < 0) {
// symbol name not found
if (modulp->symbols[symi].st_bind & STB_WEAK) {
// weak symbol not found
symu.name = symbolNameBuffer.pushString(symname);
iu = unresWeakSym.findFirst(symu);
if (iu >= 0) {
return unresWeakSym[iu].symx;
}
// strong symbol not found
err.submit(ERR_REL_SYMBOL_NOT_FOUND); return 0; // should not occur
}
}
if (symbolExports[ie].library > 0xFFFFFFF0) {
symu.name = symbolNameBuffer.pushString(symname);
iu = unresWeakSym.findFirst(symu);
if (iu >= 0) {
return unresWeakSym[iu].symx;
}
}
// module containing target symbol
modt = symbolExports[ie].member;
uint32_t symlib = symbolExports[ie].library;
if (symlib != 0 && symlib < 0xFFFFFFF0) {
modt = (uint32_t)findModule(symbolExports[ie].library, modt);
if ((int32_t)modt < 0) {
err.submit(ERR_REL_SYMBOL_NOT_FOUND); return 0; // should not occur
}
}
else if (symlib) {
modt = symlib;
}
symx.modul = modt;
symx.symi = symbolExports[ie].symindex;
// find new index for this symbol
is = symbolXref.findFirst(symx);
if (is < 0) {
err.submit(ERR_REL_SYMBOL_NOT_FOUND); return 0; // should not occur
}
return symbolXref[is].symx;
}
 
// make executable file header
void CLinker::makeFileHeader() {
fileHeader.e_type = ET_EXEC; // executable file
fileHeader.e_ip_base = ip_base; // __ip_base relative to first ip based segment
fileHeader.e_datap_base = datap_base; // __datap_base relative to first datap based segment
fileHeader.e_threadp_base = 0; // __threadp_base relative to first threadp based segment
fileHeader.e_entry = entry_point; // entry point for startup code
if (relinkable) fileHeader.e_flags |= EF_RELINKABLE; // relinking allowed
}

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