base: add symbol support for dynamic libraries

Libraries are loaded into the process address space using the
mmap system call. Conveniently, this happens to be a good
time to update the process symbol table with the library's
incoming symbols so we handle the table update from within the
system call.

This works just like an application's normal symbols. The only
difference between a dynamic library and a main executable is
when the symbol table update occurs. The symbol table update for
an executable happens at program load time and is finished before
the process ever begins executing. Since dynamic linking happens
at runtime, the symbol loading happens after the library is
first loaded into the process address space. The library binary
is examined at this time for a symbol section and that section
is parsed for symbol types with specific bindings (global,
local, weak). Subsequently, these symbols are added to the table
and are available for use by gem5 for things like trace
generation.

Checkpointing should work just as it did previously. The address
space (and therefore the library) will be recorded and the symbol
table will be entirely recorded. (It's not possible to do anything
clever like checkpoint a program and then load the program back
with different libraries with LD_LIBRARY_PATH, because the
library becomes part of the address space after being loaded.)

1 files changed, 6 insertions, 4 deletions

diff --git a/src/base/loader/ecoff_object.hh b/src/base/loader/ecoff_object.hh
index 0a5a43f72..b1ae91107 100644
--- a/src/base/loader/ecoff_object.hh
+++ b/src/base/loader/ecoff_object.hh
@@ -51,10 +51,12 @@ class EcoffObject : public ObjectFile
   public:
     virtual ~EcoffObject() {}
 
-    virtual bool loadGlobalSymbols(SymbolTable *symtab, Addr addrMask =
-            std::numeric_limits<Addr>::max());
-    virtual bool loadLocalSymbols(SymbolTable *symtab, Addr addrMask =
-            std::numeric_limits<Addr>::max());
+    virtual bool loadAllSymbols(SymbolTable *symtab, Addr base = 0,
+                                Addr offset = 0, Addr addr_mask = maxAddr);
+    virtual bool loadGlobalSymbols(SymbolTable *symtab, Addr base = 0,
+                                  Addr offset = 0, Addr addr_mask = maxAddr);
+    virtual bool loadLocalSymbols(SymbolTable *symtab, Addr base = 0,
+                                  Addr offset = 0, Addr addr_mask = maxAddr);
 
     static ObjectFile *tryFile(const std::string &fname,
                                size_t len, uint8_t *data);