kernel/trace/trace_preemptirq.c

// SPDX-License-Identifier: GPL-2.0
/*
 * preemptoff and irqoff tracepoints
 *
 * Copyright (C) Joel Fernandes (Google) <joel@joelfernandes.org>
 */

#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/ftrace.h>
#include <linux/kprobes.h>
#include <linux/hardirq.h>
#include "trace.h"

#define CREATE_TRACE_POINTS
#include <trace/events/preemptirq.h>

/*
 * Use regular trace points on architectures that implement noinstr
 * tooling: these calls will only happen with RCU enabled, which can
 * use a regular tracepoint.
 *
 * On older architectures, RCU may not be watching in idle. In that
 * case, wake up RCU to watch while calling the tracepoint. These
 * aren't NMI-safe - so exclude NMI contexts:
 */
#ifdef CONFIG_ARCH_WANTS_NO_INSTR
#define trace(point, args)	trace_##point(args)
#else
#define trace(point, args)					\
	do {							\
		if (__trace_##point##_enabled()) {		\
			bool exit_rcu = false;			\
			if (in_nmi())				\
				break;				\
			if (!IS_ENABLED(CONFIG_TINY_RCU) &&	\
			    is_idle_task(current)) {		\
				ct_irq_enter();			\
				exit_rcu = true;		\
			}					\
			trace_##point(args);			\
			if (exit_rcu)				\
				ct_irq_exit();			\
		}						\
	} while (0)
#endif

#ifdef CONFIG_TRACE_IRQFLAGS
/* Per-cpu variable to prevent redundant calls when IRQs already off */
static DEFINE_PER_CPU(int, tracing_irq_cpu);

/*
 * Like trace_hardirqs_on() but without the lockdep invocation. This is
 * used in the low level entry code where the ordering vs. RCU is important
 * and lockdep uses a staged approach which splits the lockdep hardirq
 * tracking into a RCU on and a RCU off section.
 */
void trace_hardirqs_on_prepare(void)
{
	if (this_cpu_read(tracing_irq_cpu)) {
		trace(irq_enable, TP_ARGS(CALLER_ADDR0, CALLER_ADDR1));
		tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
		this_cpu_write(tracing_irq_cpu, 0);
	}
}
EXPORT_SYMBOL(trace_hardirqs_on_prepare);
NOKPROBE_SYMBOL(trace_hardirqs_on_prepare);

void trace_hardirqs_on(void)
{
	if (this_cpu_read(tracing_irq_cpu)) {
		trace(irq_enable, TP_ARGS(CALLER_ADDR0, CALLER_ADDR1));
		tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
		this_cpu_write(tracing_irq_cpu, 0);
	}

	lockdep_hardirqs_on_prepare();
	lockdep_hardirqs_on(CALLER_ADDR0);
}
EXPORT_SYMBOL(trace_hardirqs_on);
NOKPROBE_SYMBOL(trace_hardirqs_on);

/*
 * Like trace_hardirqs_off() but without the lockdep invocation. This is
 * used in the low level entry code where the ordering vs. RCU is important
 * and lockdep uses a staged approach which splits the lockdep hardirq
 * tracking into a RCU on and a RCU off section.
 */
void trace_hardirqs_off_finish(void)
{
	if (!this_cpu_read(tracing_irq_cpu)) {
		this_cpu_write(tracing_irq_cpu, 1);
		tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
		trace(irq_disable, TP_ARGS(CALLER_ADDR0, CALLER_ADDR1));
	}

}
EXPORT_SYMBOL(trace_hardirqs_off_finish);
NOKPROBE_SYMBOL(trace_hardirqs_off_finish);

void trace_hardirqs_off(void)
{
	lockdep_hardirqs_off(CALLER_ADDR0);

	if (!this_cpu_read(tracing_irq_cpu)) {
		this_cpu_write(tracing_irq_cpu, 1);
		tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
		trace(irq_disable, TP_ARGS(CALLER_ADDR0, CALLER_ADDR1));
	}
}
EXPORT_SYMBOL(trace_hardirqs_off);
NOKPROBE_SYMBOL(trace_hardirqs_off);
#endif /* CONFIG_TRACE_IRQFLAGS */

#ifdef CONFIG_TRACE_PREEMPT_TOGGLE

void trace_preempt_on(unsigned long a0, unsigned long a1)
{
	trace(preempt_enable, TP_ARGS(a0, a1));
	tracer_preempt_on(a0, a1);
}

void trace_preempt_off(unsigned long a0, unsigned long a1)
{
	trace(preempt_disable, TP_ARGS(a0, a1));
	tracer_preempt_off(a0, a1);
}
#endif