x86, traps: Fix ist_enter from userspace (b926e6f6) · Commits · 戴 / test

arch/x86/kernel/traps.c

+18 −7

Original line number	Diff line number	Diff line
		@@ -110,15 +110,11 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)

		enum ctx_state ist_enter(struct pt_regs *regs)
		{
		/*
		* We are atomic because we're on the IST stack (or we're on x86_32,
		* in which case we still shouldn't schedule.
		*/
		preempt_count_add(HARDIRQ_OFFSET);
		enum ctx_state prev_state;

		if (user_mode_vm(regs)) {
		/* Other than that, we're just an exception. */
		return exception_enter();
		prev_state = exception_enter();
		} else {
		/*
		* We might have interrupted pretty much anything. In
		@@ -127,12 +123,27 @@ enum ctx_state ist_enter(struct pt_regs *regs)
		* but we need to notify RCU.
		*/
		rcu_nmi_enter();
		return IN_KERNEL; /* the value is irrelevant. */
		prev_state = IN_KERNEL; /* the value is irrelevant. */
		}

		/*
		* We are atomic because we're on the IST stack (or we're on x86_32,
		* in which case we still shouldn't schedule).
		*
		* This must be after exception_enter(), because exception_enter()
		* won't do anything if in_interrupt() returns true.
		*/
		preempt_count_add(HARDIRQ_OFFSET);

		/* This code is a bit fragile. Test it. */
		rcu_lockdep_assert(rcu_is_watching(), "ist_enter didn't work");

		return prev_state;
		}

		void ist_exit(struct pt_regs *regs, enum ctx_state prev_state)
		{
		/* Must be before exception_exit. */
		preempt_count_sub(HARDIRQ_OFFSET);

		if (user_mode_vm(regs))