Support ftrace on NDS32 architecture

This patch set implements the ftrace function and function graph tracer on NDS32 architecture. We try to use C code to do everything, so we don't need to separate the implementation to assembly code and C code, we just need one ftrace.c file.

In mcount function, we use the prologue/epilogue which generated by compiler to help us to save/restore the status. On the other hand, we use naked attribute of gcc to avoid to generate the prologue/epilogue when we don't need it(such as ftrace_stub and return_to_handler).

We pass the following tests:

1. FTRACE_STARTUP_TEST: PASS

2. tools/testing/selftests/ftrace/:

 # of passed:  28
 # of failed:  1
 # of unresolved:  0
 # of untested:  0
 # of unsupported:  38
 # of xfailed:  0
 # of undefined(test bug):  0

The failed case is func-filter-glob.tc.
When setting the '*aw*lock' to the set_ftrace_filter in this test case, we got the error because we have no these functions such as _raw_spin_lock, _raw_spin_trylock and so on in our kernel.

Zong Li (6):
nds32/ftrace: Support static function tracer nds32/ftrace: Support static function graph tracer nds32/ftrace: Add RECORD_MCOUNT support
nds32/ftrace: Support dynamic function tracer nds32/ftrace: Support dynamic function graph tracer nds32/stack: Get real return address by using ftrace_graph_ret_addr

 arch/nds32/Kconfig              |   4 +
 arch/nds32/Makefile             |   4 +
 arch/nds32/include/asm/ftrace.h |  46 +++++++
 arch/nds32/kernel/Makefile      |   6 +
 arch/nds32/kernel/ftrace.c      | 297 ++++++++++++++++++++++++++++++++++++++++
 arch/nds32/kernel/stacktrace.c  |   4 +
 arch/nds32/kernel/traps.c       |  30 +---
 scripts/recordmcount.pl         |   3 +
 8 files changed, 370 insertions(+), 24 deletions(-)
 create mode 100644 arch/nds32/include/asm/ftrace.h
 create mode 100644 arch/nds32/kernel/ftrace.c

2.7.4