v4.19.13 snapshot.
diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
new file mode 100644
index 0000000..1f86e1b
--- /dev/null
+++ b/arch/x86/include/asm/unwind.h
@@ -0,0 +1,120 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_UNWIND_H
+#define _ASM_X86_UNWIND_H
+
+#include <linux/sched.h>
+#include <linux/ftrace.h>
+#include <asm/ptrace.h>
+#include <asm/stacktrace.h>
+
+#define IRET_FRAME_OFFSET (offsetof(struct pt_regs, ip))
+#define IRET_FRAME_SIZE (sizeof(struct pt_regs) - IRET_FRAME_OFFSET)
+
+struct unwind_state {
+ struct stack_info stack_info;
+ unsigned long stack_mask;
+ struct task_struct *task;
+ int graph_idx;
+ bool error;
+#if defined(CONFIG_UNWINDER_ORC)
+ bool signal, full_regs;
+ unsigned long sp, bp, ip;
+ struct pt_regs *regs;
+#elif defined(CONFIG_UNWINDER_FRAME_POINTER)
+ bool got_irq;
+ unsigned long *bp, *orig_sp, ip;
+ struct pt_regs *regs;
+#else
+ unsigned long *sp;
+#endif
+};
+
+void __unwind_start(struct unwind_state *state, struct task_struct *task,
+ struct pt_regs *regs, unsigned long *first_frame);
+bool unwind_next_frame(struct unwind_state *state);
+unsigned long unwind_get_return_address(struct unwind_state *state);
+unsigned long *unwind_get_return_address_ptr(struct unwind_state *state);
+
+static inline bool unwind_done(struct unwind_state *state)
+{
+ return state->stack_info.type == STACK_TYPE_UNKNOWN;
+}
+
+static inline bool unwind_error(struct unwind_state *state)
+{
+ return state->error;
+}
+
+static inline
+void unwind_start(struct unwind_state *state, struct task_struct *task,
+ struct pt_regs *regs, unsigned long *first_frame)
+{
+ first_frame = first_frame ? : get_stack_pointer(task, regs);
+
+ __unwind_start(state, task, regs, first_frame);
+}
+
+#if defined(CONFIG_UNWINDER_ORC) || defined(CONFIG_UNWINDER_FRAME_POINTER)
+/*
+ * If 'partial' returns true, only the iret frame registers are valid.
+ */
+static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
+ bool *partial)
+{
+ if (unwind_done(state))
+ return NULL;
+
+ if (partial) {
+#ifdef CONFIG_UNWINDER_ORC
+ *partial = !state->full_regs;
+#else
+ *partial = false;
+#endif
+ }
+
+ return state->regs;
+}
+#else
+static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
+ bool *partial)
+{
+ return NULL;
+}
+#endif
+
+#ifdef CONFIG_UNWINDER_ORC
+void unwind_init(void);
+void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
+ void *orc, size_t orc_size);
+#else
+static inline void unwind_init(void) {}
+static inline
+void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
+ void *orc, size_t orc_size) {}
+#endif
+
+/*
+ * This disables KASAN checking when reading a value from another task's stack,
+ * since the other task could be running on another CPU and could have poisoned
+ * the stack in the meantime.
+ */
+#define READ_ONCE_TASK_STACK(task, x) \
+({ \
+ unsigned long val; \
+ if (task == current) \
+ val = READ_ONCE(x); \
+ else \
+ val = READ_ONCE_NOCHECK(x); \
+ val; \
+})
+
+static inline bool task_on_another_cpu(struct task_struct *task)
+{
+#ifdef CONFIG_SMP
+ return task != current && task->on_cpu;
+#else
+ return false;
+#endif
+}
+
+#endif /* _ASM_X86_UNWIND_H */