[PATCH] x86_64: reliable stack trace support

These are the generic bits needed to enable reliable stack traces based
on Dwarf2-like (.eh_frame) unwind information. Subsequent patches will
enable x86-64 and i386 to make use of this.

Thanks to Andi Kleen and Ingo Molnar, who pointed out several possibilities
for improvement.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

lib/Kconfig.debug

@@ -188,14 +188,22 @@ config FRAME_POINTER
 
 config UNWIND_INFO
 	bool "Compile the kernel with frame unwind information"
-	depends on !IA64
-	depends on !MODULES || !(MIPS || PARISC || PPC || SUPERH || V850)
+	depends on !IA64 && !PARISC
+	depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
 	help
 	  If you say Y here the resulting kernel image will be slightly larger
 	  but not slower, and it will give very useful debugging information.
 	  If you don't debug the kernel, you can say N, but we may not be able
 	  to solve problems without frame unwind information or frame pointers.
 
+config STACK_UNWIND
+	bool "Stack unwind support"
+	depends on UNWIND_INFO
+	depends on n
+	help
+	  This enables more precise stack traces, omitting all unrelated
+	  occurrences of pointers into kernel code from the dump.
+
 config FORCED_INLINING
 	bool "Force gcc to inline functions marked 'inline'"
 	depends on DEBUG_KERNEL