ld.so will now go through all DT_NEEDED entries in the dynamic table and load and relocate
those shared libraries as well. Lazy linking of functions via the PLT is not yet supported,
all PLT entries are looked up ahead of time by ld.so.
This commit includes a number of changes to enable loading of PIE
executables:
- The loader in srv.init checks for a `PT_INTERP` segment in the program
its loading, and if it exists, loads the specified interpreter and
passes control to it instead of the program itself.
- Added ld.so the dynamic linker executable and set it as the
interpreter for all user-target programs.
- Program initial stack changed again to now contain a number of
possible tagged structures, including a new one for ld.so's arguments,
and for passing handles tagged with protocol ids.
- Added a stub for a new VFS protocol. Unused so far, but srv.init will
need to serve VFS requests from ld.so once I transition libraries to
shared libs for user-target programs. (Right now all executables are
PIE but statically linked, so they only need internal relocations.)
- Added 16 and 8 bit variants of `util::bitset`. This ended up not being
used, but could be useful.
