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 <[email protected]>

1 files changed, 8 insertions, 1 deletions

diff --git a/libebl/eblinitreg.c b/libebl/eblinitreg.c
index 8909c500..5729b3cc 100644
--- a/libebl/eblinitreg.c
+++ b/libebl/eblinitreg.c
@@ -1,5 +1,5 @@
 /* Fetch live process Dwfl_Frame from PID.
-   Copyright (C) 2013 Red Hat, Inc.
+   Copyright (C) 2013, 2014 Red Hat, Inc.
    This file is part of elfutils.
 
    This file is free software; you can redistribute it and/or modify
@@ -49,3 +49,10 @@ ebl_frame_nregs (Ebl *ebl)
 {
   return ebl == NULL ? 0 : ebl->frame_nregs;
 }
+
+GElf_Addr
+ebl_func_addr_mask (Ebl *ebl)
+{
+  return ((ebl == NULL || ebl->func_addr_mask == 0)
+	  ? ~(GElf_Addr)0 : ebl->func_addr_mask);
+}