oprofile/x86: Add regs->ip to oprofile trace

dump_trace() doesn't add the interrupted instruction's address to the
trace, so add it manually.  This makes the profile more useful, and also
makes it more consistent with what perf profiling does.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Robert Richter <rric@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/6c745a83dbd69fc6857ef9b2f8be0f011d775936.1472057064.git.jpoimboe@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/oprofile/backtrace.c

@@ -114,7 +114,14 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
 
 	if (!user_mode(regs)) {
 		unsigned long stack = kernel_stack_pointer(regs);
-		if (depth)
+
+		if (!depth)
+			return;
+
+		oprofile_add_trace(regs->ip);
+		if (!--depth)
+			return;
+
 		dump_trace(NULL, regs, (unsigned long *)stack, 0,
 			   &backtrace_ops, &depth);
 		return;