diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index c4a57be9cde408ce53a3ec73f7cc2bb5518c8c8f..efebbffcd5cc971dfc5197e32eea6bbdd991dc2c 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -307,4 +307,66 @@ void irqentry_enter_from_user_mode(struct pt_regs *regs);
*/
void irqentry_exit_to_user_mode(struct pt_regs *regs);
+#ifndef irqentry_state
+typedef struct irqentry_state {
+ bool exit_rcu;
+} irqentry_state_t;
+#endif
+
+/**
+ * irqentry_enter - Handle state tracking on ordinary interrupt entries
+ * @regs: Pointer to pt_regs of interrupted context
+ *
+ * Invokes:
+ * - lockdep irqflag state tracking as low level ASM entry disabled
+ * interrupts.
+ *
+ * - Context tracking if the exception hit user mode.
+ *
+ * - The hardirq tracer to keep the state consistent as low level ASM
+ * entry disabled interrupts.
+ *
+ * As a precondition, this requires that the entry came from user mode,
+ * idle, or a kernel context in which RCU is watching.
+ *
+ * For kernel mode entries RCU handling is done conditional. If RCU is
+ * watching then the only RCU requirement is to check whether the tick has
+ * to be restarted. If RCU is not watching then rcu_irq_enter() has to be
+ * invoked on entry and rcu_irq_exit() on exit.
+ *
+ * Avoiding the rcu_irq_enter/exit() calls is an optimization but also
+ * solves the problem of kernel mode pagefaults which can schedule, which
+ * is not possible after invoking rcu_irq_enter() without undoing it.
+ *
+ * For user mode entries irqentry_enter_from_user_mode() is invoked to
+ * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit
+ * would not be possible.
+ *
+ * Returns: An opaque object that must be passed to idtentry_exit()
+ */
+irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
+
+/**
+ * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt
+ *
+ * Conditional reschedule with additional sanity checks.
+ */
+void irqentry_exit_cond_resched(void);
+
+/**
+ * irqentry_exit - Handle return from exception that used irqentry_enter()
+ * @regs: Pointer to pt_regs (exception entry regs)
+ * @state: Return value from matching call to irqentry_enter()
+ *
+ * Depending on the return target (kernel/user) this runs the necessary
+ * preemption and work checks if possible and reguired and returns to
+ * the caller with interrupts disabled and no further work pending.
+ *
+ * This is the last action before returning to the low level ASM code which
+ * just needs to return to the appropriate context.
+ *
+ * Counterpart to irqentry_enter().
+ */
+void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
+
#endif
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 0a051bb91a56cfc42012c34203c16f29f109e9d9..495f5c051b03de8fe4422695aeff1cc42f1d86fd 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -255,3 +255,120 @@ noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
instrumentation_end();
exit_to_user_mode();
}
+
+irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs)
+{
+ irqentry_state_t ret = {
+ .exit_rcu = false,
+ };
+
+ if (user_mode(regs)) {
+ irqentry_enter_from_user_mode(regs);
+ return ret;
+ }
+
+ /*
+ * If this entry hit the idle task invoke rcu_irq_enter() whether
+ * RCU is watching or not.
+ *
+ * Interupts can nest when the first interrupt invokes softirq
+ * processing on return which enables interrupts.
+ *
+ * Scheduler ticks in the idle task can mark quiescent state and
+ * terminate a grace period, if and only if the timer interrupt is
+ * not nested into another interrupt.
+ *
+ * Checking for __rcu_is_watching() here would prevent the nesting
+ * interrupt to invoke rcu_irq_enter(). If that nested interrupt is
+ * the tick then rcu_flavor_sched_clock_irq() would wrongfully
+ * assume that it is the first interupt and eventually claim
+ * quiescient state and end grace periods prematurely.
+ *
+ * Unconditionally invoke rcu_irq_enter() so RCU state stays
+ * consistent.
+ *
+ * TINY_RCU does not support EQS, so let the compiler eliminate
+ * this part when enabled.
+ */
+ if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {
+ /*
+ * If RCU is not watching then the same careful
+ * sequence vs. lockdep and tracing is required
+ * as in irq_enter_from_user_mode().
+ */
+ lockdep_hardirqs_off(CALLER_ADDR0);
+ rcu_irq_enter();
+ instrumentation_begin();
+ trace_hardirqs_off_finish();
+ instrumentation_end();
+
+ ret.exit_rcu = true;
+ return ret;
+ }
+
+ /*
+ * If RCU is watching then RCU only wants to check whether it needs
+ * to restart the tick in NOHZ mode. rcu_irq_enter_check_tick()
+ * already contains a warning when RCU is not watching, so no point
+ * in having another one here.
+ */
+ instrumentation_begin();
+ rcu_irq_enter_check_tick();
+ /* Use the combo lockdep/tracing function */
+ trace_hardirqs_off();
+ instrumentation_end();
+
+ return ret;
+}
+
+void irqentry_exit_cond_resched(void)
+{
+ if (!preempt_count()) {
+ /* Sanity check RCU and thread stack */
+ rcu_irq_exit_check_preempt();
+ if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
+ WARN_ON_ONCE(!on_thread_stack());
+ if (need_resched())
+ preempt_schedule_irq();
+ }
+}
+
+void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
+{
+ lockdep_assert_irqs_disabled();
+
+ /* Check whether this returns to user mode */
+ if (user_mode(regs)) {
+ irqentry_exit_to_user_mode(regs);
+ } else if (!regs_irqs_disabled(regs)) {
+ /*
+ * If RCU was not watching on entry this needs to be done
+ * carefully and needs the same ordering of lockdep/tracing
+ * and RCU as the return to user mode path.
+ */
+ if (state.exit_rcu) {
+ instrumentation_begin();
+ /* Tell the tracer that IRET will enable interrupts */
+ trace_hardirqs_on_prepare();
+ lockdep_hardirqs_on_prepare(CALLER_ADDR0);
+ instrumentation_end();
+ rcu_irq_exit();
+ lockdep_hardirqs_on(CALLER_ADDR0);
+ return;
+ }
+
+ instrumentation_begin();
+ if (IS_ENABLED(CONFIG_PREEMPTION))
+ irqentry_exit_cond_resched();
+ /* Covers both tracing and lockdep */
+ trace_hardirqs_on();
+ instrumentation_end();
+ } else {
+ /*
+ * IRQ flags state is correct already. Just tell RCU if it
+ * was not watching on entry.
+ */
+ if (state.exit_rcu)
+ rcu_irq_exit();
+ }
+}