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#ifndef _LINUX_CONTEXT_TRACKING_H
#define _LINUX_CONTEXT_TRACKING_H
#include <linux/sched.h>
#include <linux/percpu.h>
#include <asm/ptrace.h>
struct context_tracking {
/*
* When active is false, probes are unset in order
* to minimize overhead: TIF flags are cleared
* and calls to user_enter/exit are ignored. This
* may be further optimized using static keys.
*/
bool active;
enum ctx_state {
IN_KERNEL = 0,
IN_USER,
} state;
};
#ifdef CONFIG_CONTEXT_TRACKING
DECLARE_PER_CPU(struct context_tracking, context_tracking);
static inline bool context_tracking_in_user(void)
{
return __this_cpu_read(context_tracking.state) == IN_USER;
}
static inline bool context_tracking_active(void)
{
return __this_cpu_read(context_tracking.active);
}
extern void user_enter(void);
extern void user_exit(void);
static inline enum ctx_state exception_enter(void)
{
enum ctx_state prev_ctx;
prev_ctx = this_cpu_read(context_tracking.state);
user_exit();
return prev_ctx;
}
static inline void exception_exit(enum ctx_state prev_ctx)
{
if (prev_ctx == IN_USER)
user_enter();
}
extern void context_tracking_task_switch(struct task_struct *prev,
struct task_struct *next);
#else
static inline bool context_tracking_in_user(void) { return false; }
static inline void user_enter(void) { }
static inline void user_exit(void) { }
static inline enum ctx_state exception_enter(void) { return 0; }
static inline void exception_exit(enum ctx_state prev_ctx) { }
static inline void context_tracking_task_switch(struct task_struct *prev,
struct task_struct *next) { }
#endif /* !CONFIG_CONTEXT_TRACKING */
#endif
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