From 4a9dd1feb846e015303196ad5274a829a7c18525 Mon Sep 17 00:00:00 2001 From: Brandon Potter Date: Thu, 17 Mar 2016 10:34:27 -0700 Subject: 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.) --- src/base/loader/object_file.hh | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) (limited to 'src/base/loader/object_file.hh') diff --git a/src/base/loader/object_file.hh b/src/base/loader/object_file.hh index fb30118e0..b2628a0d0 100644 --- a/src/base/loader/object_file.hh +++ b/src/base/loader/object_file.hh @@ -82,15 +82,19 @@ class ObjectFile public: virtual ~ObjectFile(); - virtual bool loadSections(PortProxy& memProxy, Addr addrMask = - std::numeric_limits::max(), - Addr offset = 0); - virtual bool loadGlobalSymbols(SymbolTable *symtab, Addr addrMask = - std::numeric_limits::max()) = 0; - virtual bool loadLocalSymbols(SymbolTable *symtab, Addr addrMask = - std::numeric_limits::max()) = 0; - virtual bool loadWeakSymbols(SymbolTable *symtab, Addr addrMask = - std::numeric_limits::max()) + static const Addr maxAddr = std::numeric_limits::max(); + + virtual bool loadSections(PortProxy& mem_proxy, + Addr mask = maxAddr, Addr offset = 0); + + virtual bool loadAllSymbols(SymbolTable *symtab, Addr base = 0, + Addr offset = 0, Addr mask = maxAddr) = 0; + virtual bool loadGlobalSymbols(SymbolTable *symtab, Addr base = 0, + Addr offset = 0, Addr mask = maxAddr) = 0; + virtual bool loadLocalSymbols(SymbolTable *symtab, Addr base = 0, + Addr offset = 0, Addr mask = maxAddr) = 0; + virtual bool loadWeakSymbols(SymbolTable *symtab, Addr base = 0, + Addr offset = 0, Addr mask = maxAddr) { return false; } virtual ObjectFile *getInterpreter() const { return nullptr; } @@ -121,7 +125,7 @@ class ObjectFile Section data; Section bss; - bool loadSection(Section *sec, PortProxy& memProxy, Addr addrMask, + bool loadSection(Section *sec, PortProxy& mem_proxy, Addr mask, Addr offset = 0); void setGlobalPointer(Addr global_ptr) { globalPtr = global_ptr; } -- cgit v1.2.3