1 files changed, 49 insertions, 0 deletions
diff --git a/arch/s390/include/asm/switch_to.h b/arch/s390/include/asm/switch_to.h
new file mode 100644
index 000000000..c61b2cc1a
--- /dev/null
+++ b/arch/s390/include/asm/switch_to.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright IBM Corp. 1999, 2009
+ *
+ * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#ifndef __ASM_SWITCH_TO_H
+#define __ASM_SWITCH_TO_H
+
+#include <linux/thread_info.h>
+#include <asm/fpu/api.h>
+#include <asm/ptrace.h>
+#include <asm/guarded_storage.h>
+
+extern struct task_struct *__switch_to(void *, void *);
+extern void update_cr_regs(struct task_struct *task);
+
+static inline void save_access_regs(unsigned int *acrs)
+{
+	typedef struct { int _[NUM_ACRS]; } acrstype;
+
+	asm volatile("stam 0,15,%0" : "=Q" (*(acrstype *)acrs));
+}
+
+static inline void restore_access_regs(unsigned int *acrs)
+{
+	typedef struct { int _[NUM_ACRS]; } acrstype;
+
+	asm volatile("lam 0,15,%0" : : "Q" (*(acrstype *)acrs));
+}
+
+#define switch_to(prev, next, last) do {				\
+	/* save_fpu_regs() sets the CIF_FPU flag, which enforces	\
+	 * a restore of the floating point / vector registers as	\
+	 * soon as the next task returns to user space			\
+	 */								\
+	save_fpu_regs();						\
+	save_access_regs(&prev->thread.acrs[0]);			\
+	save_ri_cb(prev->thread.ri_cb);					\
+	save_gs_cb(prev->thread.gs_cb);					\
+	update_cr_regs(next);						\
+	restore_access_regs(&next->thread.acrs[0]);			\
+	restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb);		\
+	restore_gs_cb(next->thread.gs_cb);				\
+	prev = __switch_to(prev, next);					\
+} while (0)
+
+#endif /* __ASM_SWITCH_TO_H */