[ARM/FDPIC v6 06/24] [ARM] FDPIC: Add support for c++ exceptions

The main difference with existing support is that function addresses
are function descriptor addresses instead. This means that all code
dealing with function pointers now has to cope with function
descriptors instead.

For the same reason, Linux kernel helpers can no longer be called by
dereferencing their address, so we implement wrappers that directly
call the kernel helpers.

When restoring a function address, we also have to restore the FDPIC
register value (r9).

2019-09-10  Christophe Lyon  <christophe.lyon@st.com>
	Mickaël Guêné <mickael.guene@st.com>

	gcc/
	* ginclude/unwind-arm-common.h (unwinder_cache): Add reserved5
	field.

	libgcc/
	* config/arm/linux-atomic.c (__kernel_cmpxchg): Add FDPIC support.
	(__kernel_dmb): Likewise.
	(__fdpic_cmpxchg): New function.
	(__fdpic_dmb): New function.
	* config/arm/unwind-arm.h (FDPIC_REGNUM): New define.
	(gnu_Unwind_Find_got): New function.
	(_Unwind_decode_typeinfo_ptr): Add FDPIC support.
	* unwind-arm-common.inc (UCB_PR_GOT): New.
	(funcdesc_t): New struct.
	(get_eit_entry): Add FDPIC support.
	(unwind_phase2): Likewise.
	(unwind_phase2_forced): Likewise.
	(__gnu_Unwind_RaiseException): Likewise.
	(__gnu_Unwind_Resume): Likewise.
	(__gnu_Unwind_Backtrace): Likewise.
	* unwind-pe.h (read_encoded_value_with_base): Likewise.

	libstdc++/
	* libsupc++/eh_personality.cc (get_ttype_entry): Add FDPIC
	support.


Co-Authored-By: Mickaël Guêné <mickael.guene@st.com>

From-SVN: r275568