xref: /openbmc/linux/arch/riscv/include/asm/switch_to.h (revision 3a2df632)
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/hwcap.h>
13 #include <asm/processor.h>
14 #include <asm/ptrace.h>
15 #include <asm/csr.h>
16 
17 #ifdef CONFIG_FPU
18 extern void __fstate_save(struct task_struct *save_to);
19 extern void __fstate_restore(struct task_struct *restore_from);
20 
__fstate_clean(struct pt_regs * regs)21 static inline void __fstate_clean(struct pt_regs *regs)
22 {
23 	regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
24 }
25 
fstate_off(struct task_struct * task,struct pt_regs * regs)26 static 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 
fstate_save(struct task_struct * task,struct pt_regs * regs)32 static 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 
fstate_restore(struct task_struct * task,struct pt_regs * regs)41 static 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 
__switch_to_fpu(struct task_struct * prev,struct task_struct * next)50 static 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 	if (unlikely(regs->status & SR_SD))
57 		fstate_save(prev, regs);
58 	fstate_restore(next, task_pt_regs(next));
59 }
60 
has_fpu(void)61 static __always_inline bool has_fpu(void)
62 {
63 	return riscv_has_extension_likely(RISCV_ISA_EXT_f) ||
64 		riscv_has_extension_likely(RISCV_ISA_EXT_d);
65 }
66 #else
has_fpu(void)67 static __always_inline bool has_fpu(void) { return false; }
68 #define fstate_save(task, regs) do { } while (0)
69 #define fstate_restore(task, regs) do { } while (0)
70 #define __switch_to_fpu(__prev, __next) do { } while (0)
71 #endif
72 
73 extern struct task_struct *__switch_to(struct task_struct *,
74 				       struct task_struct *);
75 
76 #define switch_to(prev, next, last)			\
77 do {							\
78 	struct task_struct *__prev = (prev);		\
79 	struct task_struct *__next = (next);		\
80 	if (has_fpu())					\
81 		__switch_to_fpu(__prev, __next);	\
82 	if (has_vector())					\
83 		__switch_to_vector(__prev, __next);	\
84 	((last) = __switch_to(__prev, __next));		\
85 } while (0)
86 
87 #endif /* _ASM_RISCV_SWITCH_TO_H */
88