x86/dumpstack: Remove unnecessary stack pointer arguments

When calling show_stack_log_lvl() or dump_trace() with a regs argument,
providing a stack pointer or frame pointer is redundant.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>d
Reviewed-by: Andy Lutomirski <luto@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/1694e2e955e3b9a73a3c3d5ba2634344014dd550.1472057064.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/oprofile/backtrace.c

@@ -113,8 +113,6 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
 	struct stack_frame *head = (struct stack_frame *)frame_pointer(regs);
 
 	if (!user_mode(regs)) {
-		unsigned long stack = kernel_stack_pointer(regs);
-
 		if (!depth)
 			return;
 
@@ -122,8 +120,7 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
 		if (!--depth)
 			return;
 
-		dump_trace(NULL, regs, (unsigned long *)stack, 0,
-			   &backtrace_ops, &depth);
+		dump_trace(NULL, regs, NULL, 0, &backtrace_ops, &depth);
 		return;
 	}