| 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(&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(&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 |