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 <linux/instrumentation.h>
   9
  10 #include <asm/ptrace.h>
  11
  12
  13 #ifdef CONFIG_CONTEXT_TRACKING
  14 extern void context_tracking_cpu_set(int cpu);
  15
  16 /* Called with interrupts disabled.  */
  17 extern void __context_tracking_enter(enum ctx_state state);
  18 extern void __context_tracking_exit(enum ctx_state state);
  19
  20 extern void context_tracking_enter(enum ctx_state state);
  21 extern void context_tracking_exit(enum ctx_state state);
  22 extern void context_tracking_user_enter(void);
  23 extern void context_tracking_user_exit(void);
  24
  25 static inline void user_enter(void)
  26 {
  27         if (context_tracking_enabled())
  28                 context_tracking_enter(CONTEXT_USER);
  29
  30 }
  31 static inline void user_exit(void)
  32 {
  33         if (context_tracking_enabled())
  34                 context_tracking_exit(CONTEXT_USER);
  35 }
  36
  37 /* Called with interrupts disabled.  */
  38 static __always_inline void user_enter_irqoff(void)
  39 {
  40         if (context_tracking_enabled())
  41                 __context_tracking_enter(CONTEXT_USER);
  42
  43 }
  44 static __always_inline void user_exit_irqoff(void)
  45 {
  46         if (context_tracking_enabled())
  47                 __context_tracking_exit(CONTEXT_USER);
  48 }
  49
  50 static inline enum ctx_state exception_enter(void)
  51 {
  52         enum ctx_state prev_ctx;
  53
  54         if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) ||
  55             !context_tracking_enabled())
  56                 return 0;
  57
  58         prev_ctx = this_cpu_read(context_tracking.state);
  59         if (prev_ctx != CONTEXT_KERNEL)
  60                 context_tracking_exit(prev_ctx);
  61
  62         return prev_ctx;
  63 }
  64
  65 static inline void exception_exit(enum ctx_state prev_ctx)
  66 {
  67         if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) &&
  68             context_tracking_enabled()) {
  69                 if (prev_ctx != CONTEXT_KERNEL)
  70                         context_tracking_enter(prev_ctx);
  71         }
  72 }
  73
  74
  75 /**
  76  * ct_state() - return the current context tracking state if known
  77  *
  78  * Returns the current cpu's context tracking state if context tracking
  79  * is enabled.  If context tracking is disabled, returns
  80  * CONTEXT_DISABLED.  This should be used primarily for debugging.
  81  */
  82 static __always_inline enum ctx_state ct_state(void)
  83 {
  84         return context_tracking_enabled() ?
  85                 this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
  86 }
  87 #else
  88 static inline void user_enter(void) { }
  89 static inline void user_exit(void) { }
  90 static inline void user_enter_irqoff(void) { }
  91 static inline void user_exit_irqoff(void) { }
  92 static inline enum ctx_state exception_enter(void) { return 0; }
  93 static inline void exception_exit(enum ctx_state prev_ctx) { }
  94 static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
  95 #endif /* !CONFIG_CONTEXT_TRACKING */
  96
  97 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
  98
  99 #ifdef CONFIG_CONTEXT_TRACKING_FORCE
 100 extern void context_tracking_init(void);
 101 #else
 102 static inline void context_tracking_init(void) { }
 103 #endif /* CONFIG_CONTEXT_TRACKING_FORCE */
 104
 105
 106 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 107 /* must be called with irqs disabled */
 108 static __always_inline void guest_enter_irqoff(void)
 109 {
 110         instrumentation_begin();
 111         if (vtime_accounting_enabled_this_cpu())
 112                 vtime_guest_enter(current);
 113         else
 114                 current->flags |= PF_VCPU;
 115         instrumentation_end();
 116
 117         if (context_tracking_enabled())
 118                 __context_tracking_enter(CONTEXT_GUEST);
 119
 120         /* KVM does not hold any references to rcu protected data when it
 121          * switches CPU into a guest mode. In fact switching to a guest mode
 122          * is very similar to exiting to userspace from rcu point of view. In
 123          * addition CPU may stay in a guest mode for quite a long time (up to
 124          * one time slice). Lets treat guest mode as quiescent state, just like
 125          * we do with user-mode execution.
 126          */
 127         if (!context_tracking_enabled_this_cpu()) {
 128                 instrumentation_begin();
 129                 rcu_virt_note_context_switch(smp_processor_id());
 130                 instrumentation_end();
 131         }
 132 }
 133
 134 static __always_inline void guest_exit_irqoff(void)
 135 {
 136         if (context_tracking_enabled())
 137                 __context_tracking_exit(CONTEXT_GUEST);
 138
 139         instrumentation_begin();
 140         if (vtime_accounting_enabled_this_cpu())
 141                 vtime_guest_exit(current);
 142         else
 143                 current->flags &= ~PF_VCPU;
 144         instrumentation_end();
 145 }
 146
 147 #else
 148 static __always_inline void guest_enter_irqoff(void)
 149 {
 150         /*
 151          * This is running in ioctl context so its safe
 152          * to assume that it's the stime pending cputime
 153          * to flush.
 154          */
 155         instrumentation_begin();
 156         vtime_account_kernel(current);
 157         current->flags |= PF_VCPU;
 158         rcu_virt_note_context_switch(smp_processor_id());
 159         instrumentation_end();
 160 }
 161
 162 static __always_inline void guest_exit_irqoff(void)
 163 {
 164         instrumentation_begin();
 165         /* Flush the guest cputime we spent on the guest */
 166         vtime_account_kernel(current);
 167         current->flags &= ~PF_VCPU;
 168         instrumentation_end();
 169 }
 170 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
 171
 172 static inline void guest_exit(void)
 173 {
 174         unsigned long flags;
 175
 176         local_irq_save(flags);
 177         guest_exit_irqoff();
 178         local_irq_restore(flags);
 179 }
 180
 181 #endif