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 (!context_tracking_enabled())
  55                 return 0;
  56
  57         prev_ctx = this_cpu_read(context_tracking.state);
  58         if (prev_ctx != CONTEXT_KERNEL)
  59                 context_tracking_exit(prev_ctx);
  60
  61         return prev_ctx;
  62 }
  63
  64 static inline void exception_exit(enum ctx_state prev_ctx)
  65 {
  66         if (context_tracking_enabled()) {
  67                 if (prev_ctx != CONTEXT_KERNEL)
  68                         context_tracking_enter(prev_ctx);
  69         }
  70 }
  71
  72
  73 /**
  74  * ct_state() - return the current context tracking state if known
  75  *
  76  * Returns the current cpu's context tracking state if context tracking
  77  * is enabled.  If context tracking is disabled, returns
  78  * CONTEXT_DISABLED.  This should be used primarily for debugging.
  79  */
  80 static __always_inline enum ctx_state ct_state(void)
  81 {
  82         return context_tracking_enabled() ?
  83                 this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
  84 }
  85 #else
  86 static inline void user_enter(void) { }
  87 static inline void user_exit(void) { }
  88 static inline void user_enter_irqoff(void) { }
  89 static inline void user_exit_irqoff(void) { }
  90 static inline enum ctx_state exception_enter(void) { return 0; }
  91 static inline void exception_exit(enum ctx_state prev_ctx) { }
  92 static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
  93 #endif /* !CONFIG_CONTEXT_TRACKING */
  94
  95 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
  96
  97 #ifdef CONFIG_CONTEXT_TRACKING_FORCE
  98 extern void context_tracking_init(void);
  99 #else
 100 static inline void context_tracking_init(void) { }
 101 #endif /* CONFIG_CONTEXT_TRACKING_FORCE */
 102
 103
 104 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 105 /* must be called with irqs disabled */
 106 static __always_inline void guest_enter_irqoff(void)
 107 {
 108         instrumentation_begin();
 109         if (vtime_accounting_enabled_this_cpu())
 110                 vtime_guest_enter(current);
 111         else
 112                 current->flags |= PF_VCPU;
 113         instrumentation_end();
 114
 115         if (context_tracking_enabled())
 116                 __context_tracking_enter(CONTEXT_GUEST);
 117
 118         /* KVM does not hold any references to rcu protected data when it
 119          * switches CPU into a guest mode. In fact switching to a guest mode
 120          * is very similar to exiting to userspace from rcu point of view. In
 121          * addition CPU may stay in a guest mode for quite a long time (up to
 122          * one time slice). Lets treat guest mode as quiescent state, just like
 123          * we do with user-mode execution.
 124          */
 125         if (!context_tracking_enabled_this_cpu()) {
 126                 instrumentation_begin();
 127                 rcu_virt_note_context_switch(smp_processor_id());
 128                 instrumentation_end();
 129         }
 130 }
 131
 132 static __always_inline void context_tracking_guest_exit(void)
 133 {
 134         if (context_tracking_enabled())
 135                 __context_tracking_exit(CONTEXT_GUEST);
 136 }
 137
 138 static __always_inline void vtime_account_guest_exit(void)
 139 {
 140         if (vtime_accounting_enabled_this_cpu())
 141                 vtime_guest_exit(current);
 142         else
 143                 current->flags &= ~PF_VCPU;
 144 }
 145
 146 static __always_inline void guest_exit_irqoff(void)
 147 {
 148         context_tracking_guest_exit();
 149
 150         instrumentation_begin();
 151         vtime_account_guest_exit();
 152         instrumentation_end();
 153 }
 154
 155 #else
 156 static __always_inline void guest_enter_irqoff(void)
 157 {
 158         /*
 159          * This is running in ioctl context so its safe
 160          * to assume that it's the stime pending cputime
 161          * to flush.
 162          */
 163         instrumentation_begin();
 164         vtime_account_kernel(current);
 165         current->flags |= PF_VCPU;
 166         rcu_virt_note_context_switch(smp_processor_id());
 167         instrumentation_end();
 168 }
 169
 170 static __always_inline void context_tracking_guest_exit(void) { }
 171
 172 static __always_inline void vtime_account_guest_exit(void)
 173 {
 174         vtime_account_kernel(current);
 175         current->flags &= ~PF_VCPU;
 176 }
 177
 178 static __always_inline void guest_exit_irqoff(void)
 179 {
 180         instrumentation_begin();
 181         /* Flush the guest cputime we spent on the guest */
 182         vtime_account_guest_exit();
 183         instrumentation_end();
 184 }
 185 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
 186
 187 static inline void guest_exit(void)
 188 {
 189         unsigned long flags;
 190
 191         local_irq_save(flags);
 192         guest_exit_irqoff();
 193         local_irq_restore(flags);
 194 }
 195
 196 #endif