1 files changed, 128 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
new file mode 100644
index 000000000000..0e71eb82f920
--- /dev/null
+++ b/arch/riscv/include/asm/switch_to.h
@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ */
+
+#ifndef _ASM_RISCV_SWITCH_TO_H
+#define _ASM_RISCV_SWITCH_TO_H
+
+#include <linux/jump_label.h>
+#include <linux/sched/task_stack.h>
+#include <linux/mm_types.h>
+#include <asm/vector.h>
+#include <asm/cpufeature.h>
+#include <asm/processor.h>
+#include <asm/ptrace.h>
+#include <asm/csr.h>
+
+#ifdef CONFIG_FPU
+extern void __fstate_save(struct task_struct *save_to);
+extern void __fstate_restore(struct task_struct *restore_from);
+
+static inline void __fstate_clean(struct pt_regs *regs)
+{
+	regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
+}
+
+static inline void fstate_off(struct task_struct *task,
+			      struct pt_regs *regs)
+{
+	regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
+}
+
+static inline void fstate_save(struct task_struct *task,
+			       struct pt_regs *regs)
+{
+	if ((regs->status & SR_FS) == SR_FS_DIRTY) {
+		__fstate_save(task);
+		__fstate_clean(regs);
+	}
+}
+
+static inline void fstate_restore(struct task_struct *task,
+				  struct pt_regs *regs)
+{
+	if ((regs->status & SR_FS) != SR_FS_OFF) {
+		__fstate_restore(task);
+		__fstate_clean(regs);
+	}
+}
+
+static inline void __switch_to_fpu(struct task_struct *prev,
+				   struct task_struct *next)
+{
+	struct pt_regs *regs;
+
+	regs = task_pt_regs(prev);
+	fstate_save(prev, regs);
+	fstate_restore(next, task_pt_regs(next));
+}
+
+static __always_inline bool has_fpu(void)
+{
+	return riscv_has_extension_likely(RISCV_ISA_EXT_f) ||
+		riscv_has_extension_likely(RISCV_ISA_EXT_d);
+}
+#else
+static __always_inline bool has_fpu(void) { return false; }
+#define fstate_save(task, regs) do { } while (0)
+#define fstate_restore(task, regs) do { } while (0)
+#define __switch_to_fpu(__prev, __next) do { } while (0)
+#endif
+
+static inline void envcfg_update_bits(struct task_struct *task,
+				      unsigned long mask, unsigned long val)
+{
+	unsigned long envcfg;
+
+	envcfg = (task->thread.envcfg & ~mask) | val;
+	task->thread.envcfg = envcfg;
+	if (task == current)
+		csr_write(CSR_ENVCFG, envcfg);
+}
+
+static inline void __switch_to_envcfg(struct task_struct *next)
+{
+	asm volatile (ALTERNATIVE("nop", "csrw " __stringify(CSR_ENVCFG) ", %0",
+				  0, RISCV_ISA_EXT_XLINUXENVCFG, 1)
+			:: "r" (next->thread.envcfg) : "memory");
+}
+
+extern struct task_struct *__switch_to(struct task_struct *,
+				       struct task_struct *);
+
+static inline bool switch_to_should_flush_icache(struct task_struct *task)
+{
+#ifdef CONFIG_SMP
+	bool stale_mm = task->mm && task->mm->context.force_icache_flush;
+	bool stale_thread = task->thread.force_icache_flush;
+	bool thread_migrated = smp_processor_id() != task->thread.prev_cpu;
+
+	return thread_migrated && (stale_mm || stale_thread);
+#else
+	return false;
+#endif
+}
+
+#ifdef CONFIG_SMP
+#define __set_prev_cpu(thread) ((thread).prev_cpu = smp_processor_id())
+#else
+#define __set_prev_cpu(thread)
+#endif
+
+#define switch_to(prev, next, last)			\
+do {							\
+	struct task_struct *__prev = (prev);		\
+	struct task_struct *__next = (next);		\
+	__set_prev_cpu(__prev->thread);			\
+	if (has_fpu())					\
+		__switch_to_fpu(__prev, __next);	\
+	if (has_vector() || has_xtheadvector())		\
+		__switch_to_vector(__prev, __next);	\
+	if (switch_to_should_flush_icache(__next))	\
+		local_flush_icache_all();		\
+	__switch_to_envcfg(__next);			\
+	((last) = __switch_to(__prev, __next));		\
+} while (0)
+
+#endif /* _ASM_RISCV_SWITCH_TO_H */