Linker checks for multiple weak symbols.

Cause the linker to stop the build if the image has multiple instances
of the same weak symbol.  This is to prevent, for instance, two
different instances of the same Singleton<Foo> from being created in
two different modules.

Change-Id: I0204e69f191d63451a53b1f99dd226c9996bbccb
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/217
Tested-by: Jenkins Server
Reviewed-by: A. Patrick Williams III <iawillia@us.ibm.com>

1 files changed, 36 insertions, 24 deletions

diff --git a/src/build/linker/linker.C b/src/build/linker/linker.C
index 1b414608f..8e7b2f71c 100644
--- a/src/build/linker/linker.C
+++ b/src/build/linker/linker.C
@@ -109,7 +109,7 @@ struct Object
         bool write_object();
 
         /**
-         * Read relocations 
+         * Read relocations
          * @return true if no errors
          * @post sets symbols, relocs
          */
@@ -228,6 +228,7 @@ vector<Object> objects;
 ofstream modinfo;
 vector<uint64_t> all_relocations;
 vector<ModuleTable> module_tables;
+map<string,size_t> weak_symbols;
 
 //-----------------------------------------------------------------------------
 // MAIN
@@ -276,7 +277,7 @@ int main(int argc, char** argv)
                 else  // extended module
                 {
                     // allocate space for the module table in the extended image
-                    uint64_t table_size = 
+                    uint64_t table_size =
                         page_align(112*VFS_EXTENDED_MODULE_MAX);
                     fseek(output, table_size, SEEK_SET);
                 }
@@ -311,11 +312,11 @@ int main(int argc, char** argv)
         }
 
         // Write objects to their output file
-        for_each(objects.begin(), objects.end(), 
+        for_each(objects.begin(), objects.end(),
                  mem_fun_ref(&Object::write_object));
         //bind2nd(mem_fun_ref(&Object::write_object), output));
 
-        // used to find start of unallocated memory 
+        // used to find start of unallocated memory
         // goes in base binary only
         uint64_t last_address = ftell(objects[0].iv_output);
 
@@ -334,7 +335,7 @@ int main(int argc, char** argv)
 
         //
         // Create module tables
-        // 
+        //
         for(vector<ModuleTable>::iterator i = module_tables.begin();
             i != module_tables.end(); ++i)
         {
@@ -404,7 +405,7 @@ bool Object::read_object(const char* i_file)
         }
         else
         {
-            cout << "NON ELF format on file: " << i_file 
+            cout << "NON ELF format on file: " << i_file
                 << ". The file will be added as a binary blob." << endl;
             image = NULL;
         }
@@ -436,7 +437,7 @@ bool Object::read_object(const char* i_file)
                 cout << "Section " << s->name << endl;
                 cout << "\tSize " << std::dec << s->size << endl;
                 cout << "\tVMA " << std::hex << s->vma_offset << endl;
-                cout << "\tData " << std::hex << bfd_getb64(s->data) 
+                cout << "\tData " << std::hex << bfd_getb64(s->data)
                     << "..." << endl;
             }
 
@@ -457,7 +458,7 @@ bool Object::write_object()
     offset = ftell(iv_output);
 
     if(isELF())
-    {    
+    {
         // Output TEXT section.
         fseek(iv_output, text.vma_offset, SEEK_CUR);
         if (text.size != fwrite(text.data, 1, text.size, iv_output))
@@ -484,7 +485,7 @@ bool Object::write_object()
             fwrite(&zero, 0, 8 - (eof % 8), iv_output);
         }
 
-        modinfo << &name[(name.find_last_of("/")+1)] << ",0x" 
+        modinfo << &name[(name.find_last_of("/")+1)] << ",0x"
             << std::hex << offset + base_addr << endl;
     }
     else // binary blob
@@ -557,6 +558,17 @@ bool Object::read_relocation()
         }
         else if (syms[i]->flags & (BSF_LOCAL | BSF_WEAK))
         {
+            // Check weak symbol list for duplicate weak symbols.
+            if (syms[i]->flags & (BSF_WEAK))
+            {
+                if (weak_symbols[syms[i]->name]++)
+                {
+                    throw std::runtime_error(
+                                string("Duplicate weak symbol detected: ") +
+                                s.name);
+                }
+            }
+
             s.type |= Symbol::LOCAL;
             cout << "\t\tLOCAL" << endl;
         }
@@ -665,14 +677,14 @@ bool Object::perform_local_relocations()
         if (address != i->addend)
         {
             ostringstream oss;
-            oss << "Expected " << i->addend << " found " << address 
+            oss << "Expected " << i->addend << " found " << address
                 << " at " << (offset + i->address);
             cout << oss.str() << endl;
             throw range_error(oss.str());
         }
 
         // If it is a non-ABS relocation, also need to add the symbol addr.
-        if (i->name != BFD_ABS_SECTION_NAME) 
+        if (i->name != BFD_ABS_SECTION_NAME)
         {
             Symbol& s = this->symbols[i->name];
             uint64_t symbol_addr = s.base + s.address;
@@ -687,7 +699,7 @@ bool Object::perform_local_relocations()
         fseek(iv_output, offset + i->address, SEEK_SET);
         fwrite(data, sizeof(uint64_t), 1, iv_output);
 
-        cout << "\tRelocated " << i->addend << " at " << i->address << " to " 
+        cout << "\tRelocated " << i->addend << " at " << i->address << " to "
             << relocation << endl;
     }
 }
@@ -711,8 +723,8 @@ bool Object::perform_global_relocations()
 
         char data[sizeof(uint64_t)*3];
 
-        for(int allow_local = 0; 
-            ((allow_local < 2) && (!found_symbol)); 
+        for(int allow_local = 0;
+            ((allow_local < 2) && (!found_symbol));
             allow_local++)
         {
             for(vector<Object>::iterator j = objects.begin();
@@ -722,8 +734,8 @@ bool Object::perform_global_relocations()
                 if (j->symbols.find(i->name) != j->symbols.end())
                 {
                     Symbol s = j->symbols[i->name];
-                    uint64_t symbol_addr = 
-                        j->offset + s.address + s.base; 
+                    uint64_t symbol_addr =
+                        j->offset + s.address + s.base;
 
                     if (s.type & Symbol::UNRESOLVED)
                         continue;
@@ -734,7 +746,7 @@ bool Object::perform_global_relocations()
 
                     found_symbol = true;
 
-                    if ((s.type & Symbol::FUNCTION) && 
+                    if ((s.type & Symbol::FUNCTION) &&
                         (i->type & Symbol::FUNCTION))
                     {
                         if (i->addend != 0)
@@ -758,8 +770,8 @@ bool Object::perform_global_relocations()
                             all_relocations.push_back(offset + i->address + 16);
                         }
 
-                        cout << "\tCopied relocation from " << std::hex 
-                            << j->base_addr << ':' << symbol_addr << " to " 
+                        cout << "\tCopied relocation from " << std::hex
+                            << j->base_addr << ':' << symbol_addr << " to "
                             << base_addr << ':' << offset + i->address << "."
                             << endl;
                     }
@@ -782,7 +794,7 @@ bool Object::perform_global_relocations()
                         if(!base_addr) all_relocations.push_back(offset + i->address);
 
                         cout << "\tRelocated from " << std::hex
-                            << j->base_addr << ':' 
+                            << j->base_addr << ':'
                             << symbol_addr - j->base_addr << " to "
                             << base_addr << ':' << offset + i->address << "."
                             << endl;
@@ -809,7 +821,7 @@ uint64_t Object::find_init_symbol()
     if (symbols.find(VFS_TOSTRING(VFS_SYMBOL_INIT)) == symbols.end())
         return 0;
 
-    return symbols[VFS_TOSTRING(VFS_SYMBOL_INIT)].address + 
+    return symbols[VFS_TOSTRING(VFS_SYMBOL_INIT)].address +
         offset + base_addr + data.vma_offset;
 }
 
@@ -820,7 +832,7 @@ uint64_t Object::find_start_symbol()
     if (symbols.find(VFS_TOSTRING(VFS_SYMBOL_START)) == symbols.end())
         return 0;
 
-    return symbols[VFS_TOSTRING(VFS_SYMBOL_START)].address + 
+    return symbols[VFS_TOSTRING(VFS_SYMBOL_START)].address +
         offset + base_addr + data.vma_offset;
 }
 
@@ -831,7 +843,7 @@ uint64_t Object::find_fini_symbol()
     if (symbols.find(VFS_TOSTRING(VFS_SYMBOL_FINI)) == symbols.end())
         return 0;
 
-    return symbols[VFS_TOSTRING(VFS_SYMBOL_FINI)].address + 
+    return symbols[VFS_TOSTRING(VFS_SYMBOL_FINI)].address +
         offset + base_addr + data.vma_offset;
 }
 
@@ -946,7 +958,7 @@ void ModuleTable::write_table(vector<Object> & i_objects)
         fwrite(data, sizeof(uint64_t), 1, iv_output);
 
         cout << std::hex << std::setfill('0');
-        cout << "\tAdded module " << object_name 
+        cout << "\tAdded module " << object_name
             << " page size 0x" << module_size << endl;
         cout << "\t\twith .text at 0x" << setw(16) << text_offset  << endl;
         cout << "\t\twith .data at 0x" << setw(16) << data_offset  << endl;