1 files changed, 98 insertions, 0 deletions
diff --git a/arch/s390/include/asm/unwind.h b/arch/s390/include/asm/unwind.h
new file mode 100644
index 0000000000..b8ecf04e34
--- /dev/null
+++ b/arch/s390/include/asm/unwind.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_S390_UNWIND_H
+#define _ASM_S390_UNWIND_H
+
+#include <linux/sched.h>
+#include <linux/ftrace.h>
+#include <linux/rethook.h>
+#include <linux/llist.h>
+#include <asm/ptrace.h>
+#include <asm/stacktrace.h>
+
+/*
+ * To use the stack unwinder it has to be initialized with unwind_start.
+ * There four combinations for task and regs:
+ * 1) task==NULL, regs==NULL: the unwind starts for the task that is currently
+ *    running, sp/ip picked up from the CPU registers
+ * 2) task==NULL, regs!=NULL: the unwind starts from the sp/ip found in
+ *    the struct pt_regs of an interrupt frame for the current task
+ * 3) task!=NULL, regs==NULL: the unwind starts for an inactive task with
+ *    the sp picked up from task->thread.ksp and the ip picked up from the
+ *    return address stored by __switch_to
+ * 4) task!=NULL, regs!=NULL: the sp/ip are picked up from the interrupt
+ *    frame 'regs' of a inactive task
+ * If 'first_frame' is not zero unwind_start skips unwind frames until it
+ * reaches the specified stack pointer.
+ * The end of the unwinding is indicated with unwind_done, this can be true
+ * right after unwind_start, e.g. with first_frame!=0 that can not be found.
+ * unwind_next_frame skips to the next frame.
+ * Once the unwind is completed unwind_error() can be used to check if there
+ * has been a situation where the unwinder could not correctly understand
+ * the tasks call chain.
+ */
+
+struct unwind_state {
+	struct stack_info stack_info;
+	unsigned long stack_mask;
+	struct task_struct *task;
+	struct pt_regs *regs;
+	unsigned long sp, ip;
+	int graph_idx;
+	struct llist_node *kr_cur;
+	bool reliable;
+	bool error;
+};
+
+/* Recover the return address modified by rethook and ftrace_graph. */
+static inline unsigned long unwind_recover_ret_addr(struct unwind_state *state,
+						    unsigned long ip)
+{
+	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *)state->sp);
+#ifdef CONFIG_RETHOOK
+	if (is_rethook_trampoline(ip))
+		ip = rethook_find_ret_addr(state->task, state->sp, &state->kr_cur);
+#endif
+	return ip;
+}
+
+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);
+
+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 __always_inline void unwind_start(struct unwind_state *state,
+					 struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned long first_frame)
+{
+	task = task ?: current;
+	first_frame = first_frame ?: get_stack_pointer(task, regs);
+	__unwind_start(state, task, regs, first_frame);
+}
+
+static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
+{
+	return unwind_done(state) ? NULL : state->regs;
+}
+
+#define unwind_for_each_frame(state, task, regs, first_frame)	\
+	for (unwind_start(state, task, regs, first_frame);	\
+	     !unwind_done(state);				\
+	     unwind_next_frame(state))
+
+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 /* _ASM_S390_UNWIND_H */