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 <linux/mm_types.h>
12 #include <asm/vector.h>
13 #include <asm/cpufeature.h>
14 #include <asm/processor.h>
15 #include <asm/ptrace.h>
16 #include <asm/csr.h>
17
18 #ifdef CONFIG_FPU
19 extern void __fstate_save(struct task_struct *save_to);
20 extern void __fstate_restore(struct task_struct *restore_from);
21
22 static inline void __fstate_clean(struct pt_regs *regs)
23 {
24 regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
25 }
26
27 static inline void fstate_off(struct task_struct *task,
28 struct pt_regs *regs)
29 {
30 regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
31 }
32
33 static inline void fstate_save(struct task_struct *task,
34 struct pt_regs *regs)
35 {
36 if ((regs->status & SR_FS) == SR_FS_DIRTY) {
37 __fstate_save(task);
38 __fstate_clean(regs);
39 }
40 }
41
42 static inline void fstate_restore(struct task_struct *task,
43 struct pt_regs *regs)
44 {
45 if ((regs->status & SR_FS) != SR_FS_OFF) {
46 __fstate_restore(task);
47 __fstate_clean(regs);
48 }
49 }
50
51 static inline void __switch_to_fpu(struct task_struct *prev,
52 struct task_struct *next)
53 {
54 struct pt_regs *regs;
55
56 regs = task_pt_regs(prev);
57 fstate_save(prev, regs);
58 fstate_restore(next, task_pt_regs(next));
59 }
60
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
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 static inline bool switch_to_should_flush_icache(struct task_struct *task)
77 {
78 #ifdef CONFIG_SMP
79 bool stale_mm = task->mm && task->mm->context.force_icache_flush;
80 bool stale_thread = task->thread.force_icache_flush;
81 bool thread_migrated = smp_processor_id() != task->thread.prev_cpu;
82
83 return thread_migrated && (stale_mm || stale_thread);
84 #else
85 return false;
86 #endif
87 }
88
89 #ifdef CONFIG_SMP
90 #define __set_prev_cpu(thread) ((thread).prev_cpu = smp_processor_id())
91 #else
92 #define __set_prev_cpu(thread)
93 #endif
94
95 #define switch_to(prev, next, last) \
96 do { \
97 struct task_struct *__prev = (prev); \
98 struct task_struct *__next = (next); \
99 __set_prev_cpu(__prev->thread); \
100 if (has_fpu()) \
101 __switch_to_fpu(__prev, __next); \
102 if (has_vector()) \
103 __switch_to_vector(__prev, __next); \
104 if (switch_to_should_flush_icache(__next)) \
105 local_flush_icache_all(); \
106 ((last) = __switch_to(__prev, __next)); \
107 } while (0)
108
109 #endif /* _ASM_RISCV_SWITCH_TO_H */
110
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