From d3432896dae72ee97deb850ad7bbc30329d32c0d Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 30 Jan 2008 13:33:17 +0100 Subject: x86: don't disable the APIC if it hasn't been mapped yet When the kernel panics early for some unrelated reason there would be eventually an early exception inside panic because clear_local_APIC tried to disable the not yet mapped APIC. Check for that explicitely. Signed-off-by: Andi Kleen Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/kernel/apic_32.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'arch/x86/kernel/apic_32.c') diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c index d07a603807d..35a568ea840 100644 --- a/arch/x86/kernel/apic_32.c +++ b/arch/x86/kernel/apic_32.c @@ -99,6 +99,8 @@ static DEFINE_PER_CPU(struct clock_event_device, lapic_events); /* Local APIC was disabled by the BIOS and enabled by the kernel */ static int enabled_via_apicbase; +static unsigned long apic_phys; + /* * Get the LAPIC version */ @@ -631,9 +633,14 @@ int setup_profiling_timer(unsigned int multiplier) */ void clear_local_APIC(void) { - int maxlvt = lapic_get_maxlvt(); + int maxlvt; u32 v; + /* APIC hasn't been mapped yet */ + if (!apic_phys) + return; + + maxlvt = lapic_get_maxlvt(); /* * Masking an LVT entry can trigger a local APIC error * if the vector is zero. Mask LVTERR first to prevent this. @@ -1120,8 +1127,6 @@ no_apic: */ void __init init_apic_mappings(void) { - unsigned long apic_phys; - /* * If no local APIC can be found then set up a fake all * zeroes page to simulate the local APIC and another -- cgit v1.2.3-70-g09d2