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 static __always_inline bool context_tracking_guest_enter(void)
  75 {
  76         if (context_tracking_enabled())
  77                 __context_tracking_enter(CONTEXT_GUEST);
  78
  79         return context_tracking_enabled_this_cpu();
  80 }
  81
  82 static __always_inline void context_tracking_guest_exit(void)
  83 {
  84         if (context_tracking_enabled())
  85                 __context_tracking_exit(CONTEXT_GUEST);
  86 }
  87
  88 /**
  89  * ct_state() - return the current context tracking state if known
  90  *
  91  * Returns the current cpu's context tracking state if context tracking
  92  * is enabled.  If context tracking is disabled, returns
  93  * CONTEXT_DISABLED.  This should be used primarily for debugging.
  94  */
  95 static __always_inline enum ctx_state ct_state(void)
  96 {
  97         return context_tracking_enabled() ?
  98                 this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
  99 }
 100 #else
 101 static inline void user_enter(void) { }
 102 static inline void user_exit(void) { }
 103 static inline void user_enter_irqoff(void) { }
 104 static inline void user_exit_irqoff(void) { }
 105 static inline enum ctx_state exception_enter(void) { return 0; }
 106 static inline void exception_exit(enum ctx_state prev_ctx) { }
 107 static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
 108 static inline bool context_tracking_guest_enter(void) { return false; }
 109 static inline void context_tracking_guest_exit(void) { }
 110
 111 #endif /* !CONFIG_CONTEXT_TRACKING */
 112
 113 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
 114
 115 #ifdef CONFIG_CONTEXT_TRACKING_FORCE
 116 extern void context_tracking_init(void);
 117 #else
 118 static inline void context_tracking_init(void) { }
 119 #endif /* CONFIG_CONTEXT_TRACKING_FORCE */
 120
 121 /* must be called with irqs disabled */
 122 static __always_inline void guest_enter_irqoff(void)
 123 {
 124         /*
 125          * This is running in ioctl context so its safe to assume that it's the
 126          * stime pending cputime to flush.
 127          */
 128         instrumentation_begin();
 129         vtime_account_guest_enter();
 130         instrumentation_end();
 131
 132         /*
 133          * KVM does not hold any references to rcu protected data when it
 134          * switches CPU into a guest mode. In fact switching to a guest mode
 135          * is very similar to exiting to userspace from rcu point of view. In
 136          * addition CPU may stay in a guest mode for quite a long time (up to
 137          * one time slice). Lets treat guest mode as quiescent state, just like
 138          * we do with user-mode execution.
 139          */
 140         if (!context_tracking_guest_enter()) {
 141                 instrumentation_begin();
 142                 rcu_virt_note_context_switch(smp_processor_id());
 143                 instrumentation_end();
 144         }
 145 }
 146
 147 static __always_inline void guest_exit_irqoff(void)
 148 {
 149         context_tracking_guest_exit();
 150
 151         instrumentation_begin();
 152         /* Flush the guest cputime we spent on the guest */
 153         vtime_account_guest_exit();
 154         instrumentation_end();
 155 }
 156
 157 static inline void guest_exit(void)
 158 {
 159         unsigned long flags;
 160
 161         local_irq_save(flags);
 162         guest_exit_irqoff();
 163         local_irq_restore(flags);
 164 }
 165
 166 #endif