1 files changed, 53 insertions, 0 deletions
diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c
new file mode 100644
index 000000000000..9298993dc8b7
--- /dev/null
+++ b/arch/x86/kernel/unwind_guess.c
@@ -0,0 +1,53 @@
+#include <linux/sched.h>
+#include <linux/ftrace.h>
+#include <asm/ptrace.h>
+#include <asm/bitops.h>
+#include <asm/stacktrace.h>
+#include <asm/unwind.h>
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+	if (unwind_done(state))
+		return 0;
+
+	return ftrace_graph_ret_addr(state->task, &state->graph_idx,
+				     *state->sp, state->sp);
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+	struct stack_info *info = &state->stack_info;
+
+	if (unwind_done(state))
+		return false;
+
+	do {
+		for (state->sp++; state->sp < info->end; state->sp++)
+			if (__kernel_text_address(*state->sp))
+				return true;
+
+		state->sp = info->next_sp;
+
+	} while (!get_stack_info(state->sp, state->task, info,
+				 &state->stack_mask));
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);
+
+void __unwind_start(struct unwind_state *state, struct task_struct *task,
+		    struct pt_regs *regs, unsigned long *first_frame)
+{
+	memset(state, 0, sizeof(*state));
+
+	state->task = task;
+	state->sp   = first_frame;
+
+	get_stack_info(first_frame, state->task, &state->stack_info,
+		       &state->stack_mask);
+
+	if (!__kernel_text_address(*first_frame))
+		unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(__unwind_start);