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 <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c
index d07a603..35a568e 100644
--- a/arch/x86/kernel/apic_32.c
+++ b/arch/x86/kernel/apic_32.c
@@ -99,6 +99,8 @@
/* 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 @@
*/
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 @@
*/
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