Commit 058df195 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/ioapic: Cleanup the timer_works() irqflags mess 



Mark tripped over the creative irqflags handling in the IO-APIC timer
delivery check which ends up doing:

        local_irq_save(flags);
	local_irq_enable();
        local_irq_restore(flags);

which triggered a new consistency check he's working on required for
replacing the POPF based restore with a conditional STI.

That code is a historical mess and none of this is needed. Make it
straightforward use local_irq_disable()/enable() as that's all what is
required. It is invoked from interrupt enabled code nowadays.

Reported-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarMark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/87k0tpju47.fsf@nanos.tec.linutronix.de
parent 26ab12bb

arch/x86/kernel/apic/io_apic.c

+6 −16
Original line number Diff line number Diff line
@@ -1620,21 +1620,16 @@ static void __init delay_without_tsc(void) 
static int __init timer_irq_works(void)

{

	unsigned long t1 = jiffies;

	unsigned long flags;



	if (no_timer_check)

		return 1;



	local_save_flags(flags);

	local_irq_enable();



	if (boot_cpu_has(X86_FEATURE_TSC))

		delay_with_tsc();

	else

		delay_without_tsc();



	local_irq_restore(flags);



	/*

	 * Expect a few ticks at least, to be sure some possible

	 * glue logic does not lock up after one or two first
@@ -1643,10 +1638,10 @@ static int __init timer_irq_works(void) 
	 * least one tick may be lost due to delays.

	 */



	/* jiffies wrap? */

	if (time_after(jiffies, t1 + 4))

		return 1;

	return 0;

	local_irq_disable();



	/* Did jiffies advance? */

	return time_after(jiffies, t1 + 4);

}



/*
@@ -2163,13 +2158,12 @@ static inline void __init check_timer(void) 
	struct irq_cfg *cfg = irqd_cfg(irq_data);

	int node = cpu_to_node(0);

	int apic1, pin1, apic2, pin2;

	unsigned long flags;

	int no_pin1 = 0;



	if (!global_clock_event)

		return;



	local_irq_save(flags);

	local_irq_disable();



	/*

	 * get/set the timer IRQ vector:
@@ -2237,7 +2231,6 @@ static inline void __init check_timer(void) 
			goto out;

		}

		panic_if_irq_remap("timer doesn't work through Interrupt-remapped IO-APIC");

		local_irq_disable();

		clear_IO_APIC_pin(apic1, pin1);

		if (!no_pin1)

			apic_printk(APIC_QUIET, KERN_ERR "..MP-BIOS bug: "
@@ -2261,7 +2254,6 @@ static inline void __init check_timer(void) 
		/*

		 * Cleanup, just in case ...

		 */

		local_irq_disable();

		legacy_pic->mask(0);

		clear_IO_APIC_pin(apic2, pin2);

		apic_printk(APIC_QUIET, KERN_INFO "....... failed.\n");
@@ -2278,7 +2270,6 @@ static inline void __init check_timer(void) 
		apic_printk(APIC_QUIET, KERN_INFO "..... works.\n");

		goto out;

	}

	local_irq_disable();

	legacy_pic->mask(0);

	apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_FIXED | cfg->vector);

	apic_printk(APIC_QUIET, KERN_INFO "..... failed.\n");
@@ -2297,7 +2288,6 @@ static inline void __init check_timer(void) 
		apic_printk(APIC_QUIET, KERN_INFO "..... works.\n");

		goto out;

	}

	local_irq_disable();

	apic_printk(APIC_QUIET, KERN_INFO "..... failed :(.\n");

	if (apic_is_x2apic_enabled())

		apic_printk(APIC_QUIET, KERN_INFO
@@ -2306,7 +2296,7 @@ static inline void __init check_timer(void) 
	panic("IO-APIC + timer doesn't work!  Boot with apic=debug and send a "

		"report.  Then try booting with the 'noapic' option.\n");

out:

	local_irq_restore(flags);

	local_irq_enable();

}



/*

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