base: load weak symbols from object file

Without loading weak symbols into gem5, some function names and the given PC
cannot correspond correctly, because the binding attributes of unction names
in an ELF file are not only STB_GLOBAL or STB_LOCAL, but also STB_WEAK. This
patch adds a function for loading weak symbols.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>

src/base/loader/elf_object.cc

@@ -414,6 +414,12 @@ ElfObject::loadLocalSymbols(SymbolTable *symtab, Addr addrMask)
     return loadSomeSymbols(symtab, STB_LOCAL, addrMask);
 }
 
+bool
+ElfObject::loadWeakSymbols(SymbolTable *symtab, Addr addrMask)
+{
+    return loadSomeSymbols(symtab, STB_WEAK, addrMask);
+}
+
 bool
 ElfObject::loadSections(PortProxy& memProxy, Addr addrMask)
 {

src/base/loader/elf_object.hh

@@ -71,6 +71,8 @@ class ElfObject : public ObjectFile
             std::numeric_limits<Addr>::max());
     virtual bool loadLocalSymbols(SymbolTable *symtab, Addr addrMask =
             std::numeric_limits<Addr>::max());
+    virtual bool loadWeakSymbols(SymbolTable *symtab, Addr addrMask =
+            std::numeric_limits<Addr>::max());
 
     virtual bool isDynamic() { return sectionExists(".interp"); }
     virtual bool hasTLS() { return sectionExists(".tbss"); }

src/base/loader/object_file.hh

@@ -89,6 +89,9 @@ class ObjectFile
             std::numeric_limits<Addr>::max()) = 0;
     virtual bool loadLocalSymbols(SymbolTable *symtab, Addr addrMask =
             std::numeric_limits<Addr>::max()) = 0;
+    virtual bool loadWeakSymbols(SymbolTable *symtab, Addr addrMask =
+            std::numeric_limits<Addr>::max())
+    { return false; }
 
     virtual bool isDynamic() { return false; }
     virtual bool hasTLS() { return false; }

src/sim/process.cc

@@ -574,7 +574,8 @@ LiveProcess::LiveProcess(LiveProcessParams * params, ObjectFile *_objFile)
     if (!debugSymbolTable) {
         debugSymbolTable = new SymbolTable();
         if (!objFile->loadGlobalSymbols(debugSymbolTable) ||
-            !objFile->loadLocalSymbols(debugSymbolTable)) {
+            !objFile->loadLocalSymbols(debugSymbolTable) ||
+            !objFile->loadWeakSymbols(debugSymbolTable)) {
             // didn't load any symbols
             delete debugSymbolTable;
             debugSymbolTable = NULL;