include/linux/context_tracking.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_CONTEXT_TRACKING_H
   3 #define _LINUX_CONTEXT_TRACKING_H
   4
   5 #include <linux/sched.h>
   6 #include <linux/vtime.h>
   7 #include <linux/context_tracking_state.h>
   8 #include <asm/ptrace.h>
   9
  10
  11 #ifdef CONFIG_CONTEXT_TRACKING
  12 extern void context_tracking_cpu_set(int cpu);
  13
  14 /* Called with interrupts disabled.  */
  15 extern void __context_tracking_enter(enum ctx_state state);
  16 extern void __context_tracking_exit(enum ctx_state state);
  17
  18 extern void context_tracking_enter(enum ctx_state state);
  19 extern void context_tracking_exit(enum ctx_state state);
  20 extern void context_tracking_user_enter(void);
  21 extern void context_tracking_user_exit(void);
  22
  23 static inline void user_enter(void)
  24 {
  25         if (context_tracking_enabled())
  26                 context_tracking_enter(CONTEXT_USER);
  27
  28 }
  29 static inline void user_exit(void)
  30 {
  31         if (context_tracking_enabled())
  32                 context_tracking_exit(CONTEXT_USER);
  33 }
  34
  35 /* Called with interrupts disabled.  */
  36 static __always_inline void user_enter_irqoff(void)
  37 {
  38         if (context_tracking_enabled())
  39                 __context_tracking_enter(CONTEXT_USER);
  40
  41 }
  42 static __always_inline void user_exit_irqoff(void)
  43 {
  44         if (context_tracking_enabled())
  45                 __context_tracking_exit(CONTEXT_USER);
  46 }
  47
  48 static inline enum ctx_state exception_enter(void)
  49 {
  50         enum ctx_state prev_ctx;
  51
  52         if (!context_tracking_enabled())
  53                 return 0;
  54
  55         prev_ctx = this_cpu_read(context_tracking.state);
  56         if (prev_ctx != CONTEXT_KERNEL)
  57                 context_tracking_exit(prev_ctx);
  58
  59         return prev_ctx;
  60 }
  61
  62 static inline void exception_exit(enum ctx_state prev_ctx)
  63 {
  64         if (context_tracking_enabled()) {
  65                 if (prev_ctx != CONTEXT_KERNEL)
  66                         context_tracking_enter(prev_ctx);
  67         }
  68 }
  69
  70
  71 /**
  72  * ct_state() - return the current context tracking state if known
  73  *
  74  * Returns the current cpu's context tracking state if context tracking
  75  * is enabled.  If context tracking is disabled, returns
  76  * CONTEXT_DISABLED.  This should be used primarily for debugging.
  77  */
  78 static __always_inline enum ctx_state ct_state(void)
  79 {
  80         return context_tracking_enabled() ?
  81                 this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
  82 }
  83 #else
  84 static inline void user_enter(void) { }
  85 static inline void user_exit(void) { }
  86 static inline void user_enter_irqoff(void) { }
  87 static inline void user_exit_irqoff(void) { }
  88 static inline enum ctx_state exception_enter(void) { return 0; }
  89 static inline void exception_exit(enum ctx_state prev_ctx) { }
  90 static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
  91 #endif /* !CONFIG_CONTEXT_TRACKING */
  92
  93 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
  94
  95 #ifdef CONFIG_CONTEXT_TRACKING_FORCE
  96 extern void context_tracking_init(void);
  97 #else
  98 static inline void context_tracking_init(void) { }
  99 #endif /* CONFIG_CONTEXT_TRACKING_FORCE */
 100
 101
 102 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 103 /* must be called with irqs disabled */
 104 static __always_inline void guest_enter_irqoff(void)
 105 {
 106         instrumentation_begin();
 107         if (vtime_accounting_enabled_this_cpu())
 108                 vtime_guest_enter(current);
 109         else
 110                 current->flags |= PF_VCPU;
 111         instrumentation_end();
 112
 113         if (context_tracking_enabled())
 114                 __context_tracking_enter(CONTEXT_GUEST);
 115
 116         /* KVM does not hold any references to rcu protected data when it
 117          * switches CPU into a guest mode. In fact switching to a guest mode
 118          * is very similar to exiting to userspace from rcu point of view. In
 119          * addition CPU may stay in a guest mode for quite a long time (up to
 120          * one time slice). Lets treat guest mode as quiescent state, just like
 121          * we do with user-mode execution.
 122          */
 123         if (!context_tracking_enabled_this_cpu()) {
 124                 instrumentation_begin();
 125                 rcu_virt_note_context_switch(smp_processor_id());
 126                 instrumentation_end();
 127         }
 128 }
 129
 130 static __always_inline void guest_exit_irqoff(void)
 131 {
 132         if (context_tracking_enabled())
 133                 __context_tracking_exit(CONTEXT_GUEST);
 134
 135         instrumentation_begin();
 136         if (vtime_accounting_enabled_this_cpu())
 137                 vtime_guest_exit(current);
 138         else
 139                 current->flags &= ~PF_VCPU;
 140         instrumentation_end();
 141 }
 142
 143 #else
 144 static __always_inline void guest_enter_irqoff(void)
 145 {
 146         /*
 147          * This is running in ioctl context so its safe
 148          * to assume that it's the stime pending cputime
 149          * to flush.
 150          */
 151         instrumentation_begin();
 152         vtime_account_kernel(current);
 153         current->flags |= PF_VCPU;
 154         rcu_virt_note_context_switch(smp_processor_id());
 155         instrumentation_end();
 156 }
 157
 158 static __always_inline void guest_exit_irqoff(void)
 159 {
 160         instrumentation_begin();
 161         /* Flush the guest cputime we spent on the guest */
 162         vtime_account_kernel(current);
 163         current->flags &= ~PF_VCPU;
 164         instrumentation_end();
 165 }
 166 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
 167
 168 static inline void guest_exit(void)
 169 {
 170         unsigned long flags;
 171
 172         local_irq_save(flags);
 173         guest_exit_irqoff();
 174         local_irq_restore(flags);
 175 }
 176
 177 #endif