[PATCH] x86-64: Speed up dwarf2 unwinder

This changes the dwarf2 unwinder to do a binary search for CIEs
instead of a linear work. The linker is unfortunately not
able to build a proper lookup table at link time, instead it creates
one at runtime as soon as the bootmem allocator is usable (so you'll continue
using the linear lookup for the first [hopefully] few calls).
The code should be ready to utilize a build-time created table once
a fixed linker becomes available.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>

include/linux/unwind.h

diff --git a/include/linux/unwind.h b/include/linux/unwind.h
index 73e1751..749928c 100644
--- a/include/linux/unwind.h
+++ b/include/linux/unwind.h
@@ -26,6 +26,7 @@
  * Initialize unwind support.
  */
 extern void unwind_init(void);
+extern void unwind_setup(void);
 
 #ifdef CONFIG_MODULES
 
@@ -73,6 +74,7 @@
 struct unwind_frame_info {};
 
 static inline void unwind_init(void) {}
+static inline void unwind_setup(void) {}
 
 #ifdef CONFIG_MODULES