x86: introduce frame_pointer() and stack_pointer()

This patch defines frame_pointer() and stack_pointer() similar to the
already defined instruction_pointer(). Thus the oprofile code can be
written in a more readable fashion.

[ tglx: arch/x86 adaptation ]

Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/oprofile/backtrace.c

@@ -76,16 +76,8 @@ dump_user_backtrace(struct frame_head * head)
 void
 x86_backtrace(struct pt_regs * const regs, unsigned int depth)
 {
-	struct frame_head *head;
-	unsigned long stack;
-
-#ifdef CONFIG_X86_64
-	head = (struct frame_head *)regs->rbp;
-	stack = regs->rsp;
-#else
-	head = (struct frame_head *)regs->ebp;
-	stack = regs->esp;
-#endif
+	struct frame_head *head = (struct frame_head *)frame_pointer(regs);
+	unsigned long stack = stack_pointer(regs);
 
 	if (!user_mode_vm(regs)) {
 		if (depth)