1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_CONTEXT_TRACKING_STATE_H
3 #define _LINUX_CONTEXT_TRACKING_STATE_H
5 #include <linux/percpu.h>
6 #include <linux/static_key.h>
7 #include <linux/context_tracking_irq.h>
9 /* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
10 #define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1)
13 CONTEXT_DISABLED = -1, /* returned by ct_state() if unknown */
21 /* Even value for idle, else odd. */
22 #define RCU_DYNTICKS_IDX CONTEXT_MAX
24 #define CT_STATE_MASK (CONTEXT_MAX - 1)
25 #define CT_DYNTICKS_MASK (~CT_STATE_MASK)
27 struct context_tracking {
28 #ifdef CONFIG_CONTEXT_TRACKING_USER
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.
38 #ifdef CONFIG_CONTEXT_TRACKING
41 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
42 long dynticks_nesting; /* Track process nesting level. */
43 long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */
47 #ifdef CONFIG_CONTEXT_TRACKING
48 DECLARE_PER_CPU(struct context_tracking, context_tracking);
50 static __always_inline int __ct_state(void)
52 return arch_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK;
56 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
57 static __always_inline int ct_dynticks(void)
59 return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_DYNTICKS_MASK;
62 static __always_inline int ct_dynticks_cpu(int cpu)
64 struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
66 return atomic_read(&ct->state) & CT_DYNTICKS_MASK;
69 static __always_inline int ct_dynticks_cpu_acquire(int cpu)
71 struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
73 return atomic_read_acquire(&ct->state) & CT_DYNTICKS_MASK;
76 static __always_inline long ct_dynticks_nesting(void)
78 return __this_cpu_read(context_tracking.dynticks_nesting);
81 static __always_inline long ct_dynticks_nesting_cpu(int cpu)
83 struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
85 return ct->dynticks_nesting;
88 static __always_inline long ct_dynticks_nmi_nesting(void)
90 return __this_cpu_read(context_tracking.dynticks_nmi_nesting);
93 static __always_inline long ct_dynticks_nmi_nesting_cpu(int cpu)
95 struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
97 return ct->dynticks_nmi_nesting;
99 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
101 #ifdef CONFIG_CONTEXT_TRACKING_USER
102 extern struct static_key_false context_tracking_key;
104 static __always_inline bool context_tracking_enabled(void)
106 return static_branch_unlikely(&context_tracking_key);
109 static __always_inline bool context_tracking_enabled_cpu(int cpu)
111 return context_tracking_enabled() && per_cpu(context_tracking.active, cpu);
114 static inline bool context_tracking_enabled_this_cpu(void)
116 return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
120 * ct_state() - return the current context tracking state if known
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.
126 static __always_inline int ct_state(void)
130 if (!context_tracking_enabled())
131 return CONTEXT_DISABLED;
141 static __always_inline bool context_tracking_enabled(void) { return false; }
142 static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; }
143 static __always_inline bool context_tracking_enabled_this_cpu(void) { return false; }
144 #endif /* CONFIG_CONTEXT_TRACKING_USER */