Commit 26f80681 authored by Gabriele Monaco's avatar Gabriele Monaco Committed by Steven Rostedt (Google)
Browse files

sched: Add sched tracepoints for RV task model 

Add the following tracepoints:
* sched_entry(bool preempt, ip)
    Called while entering __schedule
* sched_exit(bool is_switch, ip)
    Called while exiting __schedule
* sched_set_state(task, curr_state, state)
    Called when a task changes its state (to and from running)

These tracepoints are useful to describe the Linux task model and are
adapted from the patches by Daniel Bristot de Oliveira
(https://bristot.me/linux-task-model/).

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/20250305140406.350227-2-gmonaco@redhat.com


Signed-off-by: default avatarGabriele Monaco <gmonaco@redhat.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 41a4d2d3

include/linux/rv.h

+1 −1
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ 
#ifndef _LINUX_RV_H

#define _LINUX_RV_H



#define MAX_DA_NAME_LEN	24

#define MAX_DA_NAME_LEN	32



#ifdef CONFIG_RV

/*

include/linux/sched.h

+16 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ 
#include <linux/rv.h>

#include <linux/livepatch_sched.h>

#include <linux/uidgid_types.h>

#include <linux/tracepoint-defs.h>

#include <asm/kmap_size.h>



/* task_struct member predeclarations (sorted alphabetically): */
@@ -186,6 +187,12 @@ struct user_event_mm; 
# define debug_rtlock_wait_restore_state()	do { } while (0)

#endif



#define trace_set_current_state(state_value)                     \

	do {                                                     \

		if (tracepoint_enabled(sched_set_state_tp))      \

			__trace_set_current_state(state_value); \

	} while (0)



/*

 * set_current_state() includes a barrier so that the write of current->__state

 * is correctly serialised wrt the caller's subsequent test of whether to
@@ -226,12 +233,14 @@ struct user_event_mm; 
#define __set_current_state(state_value)				\

	do {								\

		debug_normal_state_change((state_value));		\

		trace_set_current_state(state_value);			\

		WRITE_ONCE(current->__state, (state_value));		\

	} while (0)



#define set_current_state(state_value)					\

	do {								\

		debug_normal_state_change((state_value));		\

		trace_set_current_state(state_value);			\

		smp_store_mb(current->__state, (state_value));		\

	} while (0)
@@ -247,6 +256,7 @@ struct user_event_mm; 
									\

		raw_spin_lock_irqsave(&current->pi_lock, flags);	\

		debug_special_state_change((state_value));		\

		trace_set_current_state(state_value);			\

		WRITE_ONCE(current->__state, (state_value));		\

		raw_spin_unlock_irqrestore(&current->pi_lock, flags);	\

	} while (0)
@@ -282,6 +292,7 @@ struct user_event_mm; 
		raw_spin_lock(&current->pi_lock);			\

		current->saved_state = current->__state;		\

		debug_rtlock_wait_set_state();				\

		trace_set_current_state(TASK_RTLOCK_WAIT);		\

		WRITE_ONCE(current->__state, TASK_RTLOCK_WAIT);		\

		raw_spin_unlock(&current->pi_lock);			\

	} while (0);
@@ -291,6 +302,7 @@ struct user_event_mm; 
		lockdep_assert_irqs_disabled();				\

		raw_spin_lock(&current->pi_lock);			\

		debug_rtlock_wait_restore_state();			\

		trace_set_current_state(current->saved_state);		\

		WRITE_ONCE(current->__state, current->saved_state);	\

		current->saved_state = TASK_RUNNING;			\

		raw_spin_unlock(&current->pi_lock);			\
@@ -327,6 +339,10 @@ extern void io_schedule_finish(int token); 
extern long io_schedule_timeout(long timeout);

extern void io_schedule(void);



/* wrapper function to trace from this header file */

DECLARE_TRACEPOINT(sched_set_state_tp);

extern void __trace_set_current_state(int state_value);



/**

 * struct prev_cputime - snapshot of system and user cputime

 * @utime: time spent in user mode

include/trace/events/sched.h

+13 −0
Original line number Diff line number Diff line
@@ -824,6 +824,19 @@ DECLARE_TRACE(sched_compute_energy_tp, 
		 unsigned long max_util, unsigned long busy_time),

	TP_ARGS(p, dst_cpu, energy, max_util, busy_time));



DECLARE_TRACE(sched_entry_tp,

	TP_PROTO(bool preempt, unsigned long ip),

	TP_ARGS(preempt, ip));



DECLARE_TRACE(sched_exit_tp,

	TP_PROTO(bool is_switch, unsigned long ip),

	TP_ARGS(is_switch, ip));



DECLARE_TRACE_CONDITION(sched_set_state_tp,

	TP_PROTO(struct task_struct *tsk, int state),

	TP_ARGS(tsk, state),

	TP_CONDITION(!!(tsk->__state) != !!state));



#endif /* _TRACE_SCHED_H */



/* This part must be outside protection */

kernel/sched/core.c

+22 −1
Original line number Diff line number Diff line
@@ -491,6 +491,16 @@ sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags) { } 


#endif /* CONFIG_SCHED_CORE */



/* need a wrapper since we may need to trace from modules */

EXPORT_TRACEPOINT_SYMBOL(sched_set_state_tp);



/* Call via the helper macro trace_set_current_state. */

void __trace_set_current_state(int state_value)

{

	trace_sched_set_state_tp(current, state_value);

}

EXPORT_SYMBOL(__trace_set_current_state);



/*

 * Serialization rules:

 *
@@ -5307,6 +5317,12 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev) 
	 */



	finish_task_switch(prev);

	/*

	 * This is a special case: the newly created task has just

	 * switched the context for the first time. It is returning from

	 * schedule for the first time in this path.

	 */

	trace_sched_exit_tp(true, CALLER_ADDR0);

	preempt_enable();



	if (current->set_child_tid)
@@ -6650,12 +6666,15 @@ static void __sched notrace __schedule(int sched_mode) 
	 * as a preemption by schedule_debug() and RCU.

	 */

	bool preempt = sched_mode > SM_NONE;

	bool is_switch = false;

	unsigned long *switch_count;

	unsigned long prev_state;

	struct rq_flags rf;

	struct rq *rq;

	int cpu;



	trace_sched_entry_tp(preempt, CALLER_ADDR0);



	cpu = smp_processor_id();

	rq = cpu_rq(cpu);

	prev = rq->curr;
@@ -6723,7 +6742,8 @@ static void __sched notrace __schedule(int sched_mode) 
	rq->last_seen_need_resched_ns = 0;

#endif



	if (likely(prev != next)) {

	is_switch = prev != next;

	if (likely(is_switch)) {

		rq->nr_switches++;

		/*

		 * RCU users of rcu_dereference(rq->curr) may not see
@@ -6768,6 +6788,7 @@ static void __sched notrace __schedule(int sched_mode) 
		__balance_callbacks(rq);

		raw_spin_rq_unlock_irq(rq);

	}

	trace_sched_exit_tp(is_switch, CALLER_ADDR0);

}



void __noreturn do_task_dead(void)

tools/verification/rv/include/rv.h

+1 −1
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#define MAX_DESCRIPTION 1024

#define MAX_DA_NAME_LEN	24

#define MAX_DA_NAME_LEN	32



struct monitor {

	char name[MAX_DA_NAME_LEN];