MIPS: Add DWARF unwinding to assembly

This will allow kdump dumps to work correclty with MIPS and
future DWARF unwinding of the stack to give accurate tracebacks.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16990/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Makefile

@@ -299,6 +299,10 @@ ifdef CONFIG_64BIT
 bootvars-y	+= ADDR_BITS=64
 endif
 
+# This is required to get dwarf unwinding tables into .debug_frame
+# instead of .eh_frame so we don't discard them.
+KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
+
 LDFLAGS			+= -m $(ld-emul)
 
 ifdef CONFIG_MIPS

arch/mips/include/asm/asm.h

@@ -55,6 +55,7 @@
 		.type	symbol, @function;		\
 		.ent	symbol, 0;			\
 symbol:		.frame	sp, 0, ra;			\
+		.cfi_startproc;				\
 		.insn
 
 /*
@@ -66,12 +67,14 @@ symbol:		.frame	sp, 0, ra;			\
 		.type	symbol, @function;		\
 		.ent	symbol, 0;			\
 symbol:		.frame	sp, framesize, rpc;		\
+		.cfi_startproc;				\
 		.insn
 
 /*
  * END - mark end of function
  */
 #define END(function)					\
+		.cfi_endproc;				\
 		.end	function;			\
 		.size	function, .-function