oprofile/x86: Convert x86_backtrace() to use the new unwinder

Convert oprofile's x86_backtrace() to use the new unwinder.
dump_trace() has been deprecated.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.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: Robert Richter <rric@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/412df8927705795e8ea60cffcf89a79e010713b1.1474045023.git.jpoimboe@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/oprofile/backtrace.c

@@ -16,27 +16,7 @@
 
 #include <asm/ptrace.h>
 #include <asm/stacktrace.h>
-
-static int backtrace_stack(void *data, const char *name)
-{
-	/* Yes, we want all stacks */
-	return 0;
-}
-
-static int backtrace_address(void *data, unsigned long addr, int reliable)
-{
-	unsigned int *depth = data;
-
-	if ((*depth)--)
-		oprofile_add_trace(addr);
-	return 0;
-}
-
-static struct stacktrace_ops backtrace_ops = {
-	.stack		= backtrace_stack,
-	.address	= backtrace_address,
-	.walk_stack	= print_context_stack,
-};
+#include <asm/unwind.h>
 
 #ifdef CONFIG_COMPAT
 static struct stack_frame_ia32 *
@@ -113,14 +93,29 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
 	struct stack_frame *head = (struct stack_frame *)frame_pointer(regs);
 
 	if (!user_mode(regs)) {
+		struct unwind_state state;
+		unsigned long addr;
+
 		if (!depth)
 			return;
 
 		oprofile_add_trace(regs->ip);
+
 		if (!--depth)
 			return;
 
-		dump_trace(NULL, regs, NULL, 0, &backtrace_ops, &depth);
+		for (unwind_start(&state, current, regs, NULL);
+		     !unwind_done(&state); unwind_next_frame(&state)) {
+			addr = unwind_get_return_address(&state);
+			if (!addr)
+				break;
+
+			oprofile_add_trace(addr);
+
+			if (!--depth)
+				break;
+		}
+
 		return;
 	}