libebl: Add ebl_func_addr_mask plus ARM backend implementation.

The ARM EABI says that the zero bit of function symbol st_value indicates
whether the symbol points to a THUMB or ARM function. Also the return
value address in an unwind will contain the same extra bit to indicate
whether to return to a regular ARM or THUMB function. Add a new ebl
function to mask off such bits and turn a function value into a function
address so that we get the actual value that a function symbol or return
address points to. It isn't easily possible to reuse the existing
ebl_resolve_sym_value for this purpose, so we end up with another hook
that can be used from dwfl_module_getsym, handle_cfi and elflint.

Signed-off-by: Mark Wielaard <mjw@redhat.com>
12 files changed