The problem in efi_main was that the idt was cleared before the
interrupts were disabled.
The UEFI spec states that interrupts aren't used so this shouldn't be
too much of a problem. Peripherals however don't necessarily know about
this and thus might cause interrupts to happen anyway. Even if
ExitBootServices() has been called.
This means there is a risk of an interrupt being triggered while the IDT
register is nullified and the interrupt bit hasn't been cleared,
allowing for a triple fault.
This patch fixes this by clearing the interrupt bit before the lidt
instruction.
Signed-off-by: Bart Kuivenhoven <bemk@xxxxxxxxxx>
---
arch/x86/boot/compressed/eboot.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index b7388a4..100b812 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -1267,11 +1267,11 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
desc->base2 = 0x00;
#endif /* CONFIG_X86_64 */
+ asm volatile("cli");
+
asm volatile ("lidt %0" : : "m" (*idt));
asm volatile ("lgdt %0" : : "m" (*gdt));
- asm volatile("cli");
-
return boot_params;
fail:
return NULL;
--
1.8.4
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