1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_CONTEXT_TRACKING_STATE_H |
3 | #define _LINUX_CONTEXT_TRACKING_STATE_H |
4 | |
5 | #include <linux/percpu.h> |
6 | #include <linux/static_key.h> |
7 | #include <linux/context_tracking_irq.h> |
8 | |
9 | /* Offset to allow distinguishing irq vs. task-based idle entry/exit. */ |
10 | #define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1) |
11 | |
12 | enum ctx_state { |
13 | CONTEXT_DISABLED = -1, /* returned by ct_state() if unknown */ |
14 | CONTEXT_KERNEL = 0, |
15 | CONTEXT_IDLE = 1, |
16 | CONTEXT_USER = 2, |
17 | CONTEXT_GUEST = 3, |
18 | CONTEXT_MAX = 4, |
19 | }; |
20 | |
21 | /* Even value for idle, else odd. */ |
22 | #define RCU_DYNTICKS_IDX CONTEXT_MAX |
23 | |
24 | #define CT_STATE_MASK (CONTEXT_MAX - 1) |
25 | #define CT_DYNTICKS_MASK (~CT_STATE_MASK) |
26 | |
27 | struct context_tracking { |
28 | #ifdef CONFIG_CONTEXT_TRACKING_USER |
29 | /* |
30 | * When active is false, probes are unset in order |
31 | * to minimize overhead: TIF flags are cleared |
32 | * and calls to user_enter/exit are ignored. This |
33 | * may be further optimized using static keys. |
34 | */ |
35 | bool active; |
36 | int recursion; |
37 | #endif |
38 | #ifdef CONFIG_CONTEXT_TRACKING |
39 | atomic_t state; |
40 | #endif |
41 | #ifdef CONFIG_CONTEXT_TRACKING_IDLE |
42 | long dynticks_nesting; /* Track process nesting level. */ |
43 | long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */ |
44 | #endif |
45 | }; |
46 | |
47 | #ifdef CONFIG_CONTEXT_TRACKING |
48 | DECLARE_PER_CPU(struct context_tracking, context_tracking); |
49 | #endif |
50 | |
51 | #ifdef CONFIG_CONTEXT_TRACKING_USER |
52 | static __always_inline int __ct_state(void) |
53 | { |
54 | return raw_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK; |
55 | } |
56 | #endif |
57 | |
58 | #ifdef CONFIG_CONTEXT_TRACKING_IDLE |
59 | static __always_inline int ct_dynticks(void) |
60 | { |
61 | return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_DYNTICKS_MASK; |
62 | } |
63 | |
64 | static __always_inline int ct_dynticks_cpu(int cpu) |
65 | { |
66 | struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu); |
67 | |
68 | return atomic_read(v: &ct->state) & CT_DYNTICKS_MASK; |
69 | } |
70 | |
71 | static __always_inline int ct_dynticks_cpu_acquire(int cpu) |
72 | { |
73 | struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu); |
74 | |
75 | return atomic_read_acquire(v: &ct->state) & CT_DYNTICKS_MASK; |
76 | } |
77 | |
78 | static __always_inline long ct_dynticks_nesting(void) |
79 | { |
80 | return __this_cpu_read(context_tracking.dynticks_nesting); |
81 | } |
82 | |
83 | static __always_inline long ct_dynticks_nesting_cpu(int cpu) |
84 | { |
85 | struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu); |
86 | |
87 | return ct->dynticks_nesting; |
88 | } |
89 | |
90 | static __always_inline long ct_dynticks_nmi_nesting(void) |
91 | { |
92 | return __this_cpu_read(context_tracking.dynticks_nmi_nesting); |
93 | } |
94 | |
95 | static __always_inline long ct_dynticks_nmi_nesting_cpu(int cpu) |
96 | { |
97 | struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu); |
98 | |
99 | return ct->dynticks_nmi_nesting; |
100 | } |
101 | #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */ |
102 | |
103 | #ifdef CONFIG_CONTEXT_TRACKING_USER |
104 | extern struct static_key_false context_tracking_key; |
105 | |
106 | static __always_inline bool context_tracking_enabled(void) |
107 | { |
108 | return static_branch_unlikely(&context_tracking_key); |
109 | } |
110 | |
111 | static __always_inline bool context_tracking_enabled_cpu(int cpu) |
112 | { |
113 | return context_tracking_enabled() && per_cpu(context_tracking.active, cpu); |
114 | } |
115 | |
116 | static inline bool context_tracking_enabled_this_cpu(void) |
117 | { |
118 | return context_tracking_enabled() && __this_cpu_read(context_tracking.active); |
119 | } |
120 | |
121 | /** |
122 | * ct_state() - return the current context tracking state if known |
123 | * |
124 | * Returns the current cpu's context tracking state if context tracking |
125 | * is enabled. If context tracking is disabled, returns |
126 | * CONTEXT_DISABLED. This should be used primarily for debugging. |
127 | */ |
128 | static __always_inline int ct_state(void) |
129 | { |
130 | int ret; |
131 | |
132 | if (!context_tracking_enabled()) |
133 | return CONTEXT_DISABLED; |
134 | |
135 | preempt_disable(); |
136 | ret = __ct_state(); |
137 | preempt_enable(); |
138 | |
139 | return ret; |
140 | } |
141 | |
142 | #else |
143 | static __always_inline bool context_tracking_enabled(void) { return false; } |
144 | static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; } |
145 | static __always_inline bool context_tracking_enabled_this_cpu(void) { return false; } |
146 | #endif /* CONFIG_CONTEXT_TRACKING_USER */ |
147 | |
148 | #endif |
149 | |