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_USER
 14extern void ct_cpu_track_user(int cpu);
 15
 16/* Called with interrupts disabled.  */
 17extern void __ct_user_enter(enum ctx_state state);
 18extern void __ct_user_exit(enum ctx_state state);
 19
 20extern void ct_user_enter(enum ctx_state state);
 21extern void ct_user_exit(enum ctx_state state);
 22
 23extern void user_enter_callable(void);
 24extern void user_exit_callable(void);
 25
 26static inline void user_enter(void)
 27{
 28	if (context_tracking_enabled())
 29		ct_user_enter(CT_STATE_USER);
 30
 31}
 32static inline void user_exit(void)
 33{
 34	if (context_tracking_enabled())
 35		ct_user_exit(CT_STATE_USER);
 36}
 37
 38/* Called with interrupts disabled.  */
 39static __always_inline void user_enter_irqoff(void)
 40{
 41	if (context_tracking_enabled())
 42		__ct_user_enter(CT_STATE_USER);
 43
 44}
 45static __always_inline void user_exit_irqoff(void)
 46{
 47	if (context_tracking_enabled())
 48		__ct_user_exit(CT_STATE_USER);
 49}
 50
 51static inline enum ctx_state exception_enter(void)
 52{
 53	enum ctx_state prev_ctx;
 54
 55	if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) ||
 56	    !context_tracking_enabled())
 57		return 0;
 58
 59	prev_ctx = __ct_state();
 60	if (prev_ctx != CT_STATE_KERNEL)
 61		ct_user_exit(prev_ctx);
 62
 63	return prev_ctx;
 64}
 65
 66static inline void exception_exit(enum ctx_state prev_ctx)
 67{
 68	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) &&
 69	    context_tracking_enabled()) {
 70		if (prev_ctx != CT_STATE_KERNEL)
 71			ct_user_enter(prev_ctx);
 72	}
 73}
 74
 75static __always_inline bool context_tracking_guest_enter(void)
 76{
 77	if (context_tracking_enabled())
 78		__ct_user_enter(CT_STATE_GUEST);
 79
 80	return context_tracking_enabled_this_cpu();
 81}
 82
 83static __always_inline bool context_tracking_guest_exit(void)
 84{
 85	if (context_tracking_enabled())
 86		__ct_user_exit(CT_STATE_GUEST);
 87
 88	return context_tracking_enabled_this_cpu();
 89}
 90
 91#define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
 92
 93#else
 94static inline void user_enter(void) { }
 95static inline void user_exit(void) { }
 96static inline void user_enter_irqoff(void) { }
 97static inline void user_exit_irqoff(void) { }
 98static inline int exception_enter(void) { return 0; }
 99static inline void exception_exit(enum ctx_state prev_ctx) { }
100static inline int ct_state(void) { return -1; }
101static inline int __ct_state(void) { return -1; }
102static __always_inline bool context_tracking_guest_enter(void) { return false; }
103static __always_inline bool context_tracking_guest_exit(void) { return false; }
104#define CT_WARN_ON(cond) do { } while (0)
105#endif /* !CONFIG_CONTEXT_TRACKING_USER */
106
107#ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE
108extern void context_tracking_init(void);
109#else
110static inline void context_tracking_init(void) { }
111#endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */
112
113#ifdef CONFIG_CONTEXT_TRACKING_IDLE
114extern void ct_idle_enter(void);
115extern void ct_idle_exit(void);
116
117/*
118 * Is RCU watching the current CPU (IOW, it is not in an extended quiescent state)?
119 *
120 * Note that this returns the actual boolean data (watching / not watching),
121 * whereas ct_rcu_watching() returns the RCU_WATCHING subvariable of
122 * context_tracking.state.
123 *
124 * No ordering, as we are sampling CPU-local information.
125 */
126static __always_inline bool rcu_is_watching_curr_cpu(void)
127{
128	return raw_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_RCU_WATCHING;
129}
130
131/*
132 * Increment the current CPU's context_tracking structure's ->state field
133 * with ordering.  Return the new value.
134 */
135static __always_inline unsigned long ct_state_inc(int incby)
136{
137	return raw_atomic_add_return(incby, this_cpu_ptr(&context_tracking.state));
138}
139
140static __always_inline bool warn_rcu_enter(void)
141{
142	bool ret = false;
143
144	/*
145	 * Horrible hack to shut up recursive RCU isn't watching fail since
146	 * lots of the actual reporting also relies on RCU.
147	 */
148	preempt_disable_notrace();
149	if (!rcu_is_watching_curr_cpu()) {
150		ret = true;
151		ct_state_inc(CT_RCU_WATCHING);
152	}
153
154	return ret;
155}
156
157static __always_inline void warn_rcu_exit(bool rcu)
158{
159	if (rcu)
160		ct_state_inc(CT_RCU_WATCHING);
161	preempt_enable_notrace();
162}
163
164#else
165static inline void ct_idle_enter(void) { }
166static inline void ct_idle_exit(void) { }
167
168static __always_inline bool warn_rcu_enter(void) { return false; }
169static __always_inline void warn_rcu_exit(bool rcu) { }
170#endif /* !CONFIG_CONTEXT_TRACKING_IDLE */
171
172#endif