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/hwcap.h>
12 #include <asm/processor.h>
13 #include <asm/ptrace.h>
14 #include <asm/csr.h>
15
16 #ifdef CONFIG_FPU
17 extern void __fstate_save(struct task_struct *save_to);
18 extern void __fstate_restore(struct task_struct *restore_from);
19
__fstate_clean(struct pt_regs * regs)20 static inline void __fstate_clean(struct pt_regs *regs)
21 {
22 regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
23 }
24
fstate_off(struct task_struct * task,struct pt_regs * regs)25 static inline void fstate_off(struct task_struct *task,
26 struct pt_regs *regs)
27 {
28 regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
29 }
30
fstate_save(struct task_struct * task,struct pt_regs * regs)31 static inline void fstate_save(struct task_struct *task,
32 struct pt_regs *regs)
33 {
34 if ((regs->status & SR_FS) == SR_FS_DIRTY) {
35 __fstate_save(task);
36 __fstate_clean(regs);
37 }
38 }
39
fstate_restore(struct task_struct * task,struct pt_regs * regs)40 static inline void fstate_restore(struct task_struct *task,
41 struct pt_regs *regs)
42 {
43 if ((regs->status & SR_FS) != SR_FS_OFF) {
44 __fstate_restore(task);
45 __fstate_clean(regs);
46 }
47 }
48
__switch_to_aux(struct task_struct * prev,struct task_struct * next)49 static inline void __switch_to_aux(struct task_struct *prev,
50 struct task_struct *next)
51 {
52 struct pt_regs *regs;
53
54 regs = task_pt_regs(prev);
55 if (unlikely(regs->status & SR_SD))
56 fstate_save(prev, regs);
57 fstate_restore(next, task_pt_regs(next));
58 }
59
has_fpu(void)60 static __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
has_fpu(void)66 static __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_aux(__prev, __next) do { } while (0)
70 #endif
71
72 extern struct task_struct *__switch_to(struct task_struct *,
73 struct task_struct *);
74
75 #define switch_to(prev, next, last) \
76 do { \
77 struct task_struct *__prev = (prev); \
78 struct task_struct *__next = (next); \
79 if (has_fpu()) \
80 __switch_to_aux(__prev, __next); \
81 ((last) = __switch_to(__prev, __next)); \
82 } while (0)
83
84 #endif /* _ASM_RISCV_SWITCH_TO_H */
85