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: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
---
arch/x86/kernel/apic/io_apic.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1618,21 +1618,16 @@ static void __init delay_without_tsc(voi
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
@@ -1641,10 +1636,10 @@ 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);
}
/*
@@ -2117,13 +2112,12 @@ static inline void __init check_timer(vo
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:
@@ -2191,7 +2185,6 @@ static inline void __init check_timer(vo
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: "
@@ -2215,7 +2208,6 @@ static inline void __init check_timer(vo
/*
* 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");
@@ -2232,7 +2224,6 @@ static inline void __init check_timer(vo
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");
@@ -2251,7 +2242,6 @@ static inline void __init check_timer(vo
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
@@ -2260,7 +2250,7 @@ static inline void __init check_timer(vo
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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