[PATCH/arm] Backtrace through exception frames on arm/cortex-m target

[Joel Brobecker]

> 2012-11-13  Daniel Jacobowitz  <dan@codesourcery.com>
> 	    Yao Qi  <yao@codesourcery.com>
> 
> 	* arm-tdep.c (arm_addr_bits_remove): Do not adjust the low
> 	bit of EXC_RETURN.
> 	(arm_m_exception_cache, arm_m_exception_this_id)
> 	(arm_m_exception_prev_register, arm_m_exception_unwind_sniffer)
> 	(arm_m_exception_unwind): New.
> 	(arm_gdbarch_init): Register arm_m_exception_unwind.

Yao, can you add a comment/description for each new function that
you introduce?

-- 
Joel