Linux kernel mirror (for testing)
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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
12enum 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
27struct 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
48DECLARE_PER_CPU(struct context_tracking, context_tracking);
49
50static __always_inline int __ct_state(void)
51{
52 return arch_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK;
53}
54#endif
55
56#ifdef CONFIG_CONTEXT_TRACKING_IDLE
57static __always_inline int ct_dynticks(void)
58{
59 return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_DYNTICKS_MASK;
60}
61
62static __always_inline int ct_dynticks_cpu(int cpu)
63{
64 struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
65
66 return atomic_read(&ct->state) & CT_DYNTICKS_MASK;
67}
68
69static __always_inline int ct_dynticks_cpu_acquire(int cpu)
70{
71 struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
72
73 return atomic_read_acquire(&ct->state) & CT_DYNTICKS_MASK;
74}
75
76static __always_inline long ct_dynticks_nesting(void)
77{
78 return __this_cpu_read(context_tracking.dynticks_nesting);
79}
80
81static __always_inline long ct_dynticks_nesting_cpu(int cpu)
82{
83 struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
84
85 return ct->dynticks_nesting;
86}
87
88static __always_inline long ct_dynticks_nmi_nesting(void)
89{
90 return __this_cpu_read(context_tracking.dynticks_nmi_nesting);
91}
92
93static __always_inline long ct_dynticks_nmi_nesting_cpu(int cpu)
94{
95 struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
96
97 return ct->dynticks_nmi_nesting;
98}
99#endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
100
101#ifdef CONFIG_CONTEXT_TRACKING_USER
102extern struct static_key_false context_tracking_key;
103
104static __always_inline bool context_tracking_enabled(void)
105{
106 return static_branch_unlikely(&context_tracking_key);
107}
108
109static __always_inline bool context_tracking_enabled_cpu(int cpu)
110{
111 return context_tracking_enabled() && per_cpu(context_tracking.active, cpu);
112}
113
114static inline bool context_tracking_enabled_this_cpu(void)
115{
116 return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
117}
118
119/**
120 * ct_state() - return the current context tracking state if known
121 *
122 * Returns the current cpu's context tracking state if context tracking
123 * is enabled. If context tracking is disabled, returns
124 * CONTEXT_DISABLED. This should be used primarily for debugging.
125 */
126static __always_inline int ct_state(void)
127{
128 int ret;
129
130 if (!context_tracking_enabled())
131 return CONTEXT_DISABLED;
132
133 preempt_disable();
134 ret = __ct_state();
135 preempt_enable();
136
137 return ret;
138}
139
140#else
141static __always_inline bool context_tracking_enabled(void) { return false; }
142static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; }
143static __always_inline bool context_tracking_enabled_this_cpu(void) { return false; }
144#endif /* CONFIG_CONTEXT_TRACKING_USER */
145
146#endif