x86/entry/common: Provide idtentry_enter/exit() (0ba50e86) · Commits · 戴 / test

arch/x86/entry/common.c

+99 −0

Original line number	Diff line number	Diff line
		@@ -510,3 +510,102 @@ SYSCALL_DEFINE0(ni_syscall)
		{
		return -ENOSYS;
		}

		/**
		* idtentry_enter - Handle state tracking on idtentry
		* @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.
		*
		* - RCU notification if the exception hit kernel mode.
		*
		* - The hardirq tracer to keep the state consistent as low level ASM
		* entry disabled interrupts.
		*/
		void noinstr idtentry_enter(struct pt_regs *regs)
		{
		if (user_mode(regs)) {
		enter_from_user_mode();
		} else {
		lockdep_hardirqs_off(CALLER_ADDR0);
		rcu_irq_enter();
		instrumentation_begin();
		trace_hardirqs_off_prepare();
		instrumentation_end();
		}
		}

		/**
		* idtentry_exit - Common code to handle return from exceptions
		* @regs: Pointer to pt_regs (exception entry regs)
		*
		* Depending on the return target (kernel/user) this runs the necessary
		* preemption and work checks if possible and required 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.
		*
		* Invoked by all exception/interrupt IDTENTRY handlers which are not
		* returning through the paranoid exit path (all except NMI, #DF and the IST
		* variants of #MC and #DB) and are therefore on the thread stack.
		*/
		void noinstr idtentry_exit(struct pt_regs *regs)
		{
		lockdep_assert_irqs_disabled();

		/* Check whether this returns to user mode */
		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 (!preempt_count()) {
		if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
		WARN_ON_ONCE(!on_thread_stack());
		instrumentation_begin();
		rcu_irq_exit_preempt();
		if (need_resched())
		preempt_schedule_irq();
		/* Covers both tracing and lockdep */
		trace_hardirqs_on();
		instrumentation_end();
		return;
		}
		}
		/*
		* 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.
		*/
		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);
		} else {
		/* IRQ flags state is correct already. Just tell RCU */
		rcu_irq_exit();
		}
		}

arch/x86/include/asm/idtentry.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -7,6 +7,9 @@

		#ifndef __ASSEMBLY__

		void idtentry_enter(struct pt_regs *regs);
		void idtentry_exit(struct pt_regs *regs);

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

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