1/* SPDX-License-Identifier: GPL-2.0-only */
 2/*
 3 * Copyright (C) 2012 Regents of the University of California
 4 */
 5
 6#ifndef _ASM_RISCV_SWITCH_TO_H
 7#define _ASM_RISCV_SWITCH_TO_H
 8
 9#include <linux/jump_label.h>
10#include <linux/sched/task_stack.h>
11#include <asm/vector.h>
12#include <asm/cpufeature.h>
13#include <asm/processor.h>
14#include <asm/ptrace.h>
15#include <asm/csr.h>
16
17#ifdef CONFIG_FPU
18extern void __fstate_save(struct task_struct *save_to);
19extern void __fstate_restore(struct task_struct *restore_from);
20
21static inline void __fstate_clean(struct pt_regs *regs)
22{
23	regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
24}
25
26static inline void fstate_off(struct task_struct *task,
27			      struct pt_regs *regs)
28{
29	regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
30}
31
32static inline void fstate_save(struct task_struct *task,
33			       struct pt_regs *regs)
34{
35	if ((regs->status & SR_FS) == SR_FS_DIRTY) {
36		__fstate_save(task);
37		__fstate_clean(regs);
38	}
39}
40
41static inline void fstate_restore(struct task_struct *task,
42				  struct pt_regs *regs)
43{
44	if ((regs->status & SR_FS) != SR_FS_OFF) {
45		__fstate_restore(task);
46		__fstate_clean(regs);
47	}
48}
49
50static inline void __switch_to_fpu(struct task_struct *prev,
51				   struct task_struct *next)
52{
53	struct pt_regs *regs;
54
55	regs = task_pt_regs(prev);
56	fstate_save(prev, regs);
57	fstate_restore(next, task_pt_regs(next));
58}
59
60static __always_inline bool has_fpu(void)
61{
62	return riscv_has_extension_likely(RISCV_ISA_EXT_f) ||
63		riscv_has_extension_likely(RISCV_ISA_EXT_d);
64}
65#else
66static __always_inline bool has_fpu(void) { return false; }
67#define fstate_save(task, regs) do { } while (0)
68#define fstate_restore(task, regs) do { } while (0)
69#define __switch_to_fpu(__prev, __next) do { } while (0)
70#endif
71
72extern struct task_struct *__switch_to(struct task_struct *,
73				       struct task_struct *);
74
75#define switch_to(prev, next, last)			\
76do {							\
77	struct task_struct *__prev = (prev);		\
78	struct task_struct *__next = (next);		\
79	if (has_fpu())					\
80		__switch_to_fpu(__prev, __next);	\
81	if (has_vector())					\
82		__switch_to_vector(__prev, __next);	\
83	((last) = __switch_to(__prev, __next));		\
84} while (0)
85
86#endif /* _ASM_RISCV_SWITCH_TO_H */