x86/entry: Clean up idtentry_enter/exit() leftovers (9ee01e0f) · Commits · 戴 / test

arch/x86/entry/common.c

+29 −38

Original line number	Diff line number	Diff line
		@@ -515,7 +515,6 @@ SYSCALL_DEFINE0(ni_syscall)
		* idtentry_enter_cond_rcu - Handle state tracking on idtentry with conditional
		* RCU handling
		* @regs: Pointer to pt_regs of interrupted context
		* @cond_rcu: Invoke rcu_irq_enter() only if RCU is not watching
		*
		* Invokes:
		* - lockdep irqflag state tracking as low level ASM entry disabled
		@@ -545,14 +544,14 @@ SYSCALL_DEFINE0(ni_syscall)
		* The return value must be fed into the rcu_exit argument of
		* idtentry_exit_cond_rcu().
		*/
		bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs, bool cond_rcu)
		bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs)
		{
		if (user_mode(regs)) {
		enter_from_user_mode();
		return false;
		}

		if (!cond_rcu \|\| !__rcu_is_watching()) {
		if (!__rcu_is_watching()) {
		/*
		* If RCU is not watching then the same careful
		* sequence vs. lockdep and tracing is required
		@@ -608,52 +607,44 @@ void noinstr idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit)
		if (user_mode(regs)) {
		prepare_exit_to_usermode(regs);
		} else if (regs->flags & X86_EFLAGS_IF) {
		/* Check kernel preemption, if enabled */
		if (IS_ENABLED(CONFIG_PREEMPTION)) {
		/*
		* This needs to be done very carefully.
		* idtentry_enter() invoked rcu_irq_enter(). This
		* needs to be undone before scheduling.
		*
		* Preemption is disabled inside of RCU idle
		* sections. When the task returns from
		* preempt_schedule_irq(), RCU is still watching.
		*
		* rcu_irq_exit_preempt() has additional state
		* checking if CONFIG_PROVE_RCU=y
		* 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 (rcu_exit) {
		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();

		/* Check kernel preemption, if enabled */
		if (IS_ENABLED(CONFIG_PREEMPTION)) {
		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());
		instrumentation_begin();
		if (rcu_exit)
		rcu_irq_exit_preempt();
		if (need_resched())
		preempt_schedule_irq();
		}
		}
		/* Covers both tracing and lockdep */
		trace_hardirqs_on();

		instrumentation_end();
		return;
		}
		}
		} else {
		/*
		* If preemption is disabled then this needs to be done
		* carefully with respect to RCU. The exception might come
		* from a RCU idle section in the idle task due to the fact
		* that safe_halt() enables interrupts. So this needs the
		* same ordering of lockdep/tracing and RCU as the return
		* to user mode path.
		* IRQ flags state is correct already. Just tell RCU if it
		* was not watching on entry.
		*/
		instrumentation_begin();
		/* Tell the tracer that IRET will enable interrupts */
		trace_hardirqs_on_prepare();
		lockdep_hardirqs_on_prepare(CALLER_ADDR0);
		instrumentation_end();
		if (rcu_exit)
		rcu_irq_exit();
		lockdep_hardirqs_on(CALLER_ADDR0);
		} else {
		/* IRQ flags state is correct already. Just tell RCU. */
		if (rcu_exit)
		rcu_irq_exit();
		}

arch/x86/include/asm/idtentry.h

+1 −11

Original line number	Diff line number	Diff line
		@@ -10,19 +10,9 @@
		void idtentry_enter_user(struct pt_regs *regs);
		void idtentry_exit_user(struct pt_regs *regs);

		bool idtentry_enter_cond_rcu(struct pt_regs *regs, bool cond_rcu);
		bool idtentry_enter_cond_rcu(struct pt_regs *regs);
		void idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit);

		static __always_inline void idtentry_enter(struct pt_regs *regs)
		{
		idtentry_enter_cond_rcu(regs, false);
		}

		static __always_inline void idtentry_exit(struct pt_regs *regs)
		{
		idtentry_exit_cond_rcu(regs, true);
		}

		/**
		* DECLARE_IDTENTRY - Declare functions for simple IDT entry points
		* No error code pushed by hardware

Admin message