5b206d48e5
Update a stale comment from the old vtime era and document some locking that might be non obvious. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Kevin Hilman <khilman@linaro.org>
92 lines
2.1 KiB
C
92 lines
2.1 KiB
C
#ifndef _LINUX_CONTEXT_TRACKING_H
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#define _LINUX_CONTEXT_TRACKING_H
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#include <linux/sched.h>
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#include <linux/percpu.h>
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#include <linux/vtime.h>
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#include <asm/ptrace.h>
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struct context_tracking {
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/*
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* When active is false, probes are unset in order
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* to minimize overhead: TIF flags are cleared
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* and calls to user_enter/exit are ignored. This
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* may be further optimized using static keys.
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*/
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bool active;
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enum ctx_state {
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IN_KERNEL = 0,
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IN_USER,
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} state;
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};
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#ifdef CONFIG_CONTEXT_TRACKING
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DECLARE_PER_CPU(struct context_tracking, context_tracking);
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static inline bool context_tracking_in_user(void)
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{
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return __this_cpu_read(context_tracking.state) == IN_USER;
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}
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static inline bool context_tracking_active(void)
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{
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return __this_cpu_read(context_tracking.active);
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}
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extern void user_enter(void);
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extern void user_exit(void);
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static inline enum ctx_state exception_enter(void)
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{
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enum ctx_state prev_ctx;
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prev_ctx = this_cpu_read(context_tracking.state);
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user_exit();
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return prev_ctx;
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}
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static inline void exception_exit(enum ctx_state prev_ctx)
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{
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if (prev_ctx == IN_USER)
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user_enter();
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}
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extern void context_tracking_task_switch(struct task_struct *prev,
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struct task_struct *next);
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#else
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static inline bool context_tracking_in_user(void) { return false; }
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static inline void user_enter(void) { }
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static inline void user_exit(void) { }
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static inline enum ctx_state exception_enter(void) { return 0; }
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static inline void exception_exit(enum ctx_state prev_ctx) { }
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static inline void context_tracking_task_switch(struct task_struct *prev,
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struct task_struct *next) { }
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#endif /* !CONFIG_CONTEXT_TRACKING */
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#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
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extern void guest_enter(void);
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extern void guest_exit(void);
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#else
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static inline void guest_enter(void)
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{
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/*
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* This is running in ioctl context so its safe
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* to assume that it's the stime pending cputime
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* to flush.
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*/
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vtime_account_system(current);
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current->flags |= PF_VCPU;
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}
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static inline void guest_exit(void)
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{
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/* Flush the guest cputime we spent on the guest */
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vtime_account_system(current);
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current->flags &= ~PF_VCPU;
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}
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#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
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#endif
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