Commit-ID: 0ce6cda2c75d64175394341ef60e6e1d27dd9c10
Gitweb: http://git.kernel.org/tip/0ce6cda2c75d64175394341ef60e6e1d27dd9c10
Author: Bart Kuivenhoven <bemk@xxxxxxxxxx>
AuthorDate: Mon, 23 Sep 2013 11:45:28 +0200
Committer: Matt Fleming <matt.fleming@xxxxxxxxx>
CommitDate: Mon, 30 Sep 2013 10:23:11 +0100
x86 efi: bugfix interrupt disabling sequence
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 disables the interrupt flag, while leaving the existing IDT
in place. The CPU won't care about the IDT at all as long as the
interrupt bit is off, so it's safe to leave it in place as nothing will
ever happen to it.
[ Removed the now unused 'idt' variable - Matt ]
Signed-off-by: Bart Kuivenhoven <bemk@xxxxxxxxxx>
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
---
arch/x86/boot/compressed/eboot.c | 17 ++---------------
1 file changed, 2 insertions(+), 15 deletions(-)
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 5c0dc55..a7677ba 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -748,7 +748,7 @@ free_mem_map:
struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
struct boot_params *boot_params)
{
- struct desc_ptr *gdt, *idt;
+ struct desc_ptr *gdt;
efi_loaded_image_t *image;
struct setup_header *hdr = &boot_params->hdr;
efi_status_t status;
@@ -780,17 +780,6 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
goto fail;
}
- status = efi_call_phys3(sys_table->boottime->allocate_pool,
- EFI_LOADER_DATA, sizeof(*idt),
- (void **)&idt);
- if (status != EFI_SUCCESS) {
- efi_printk(sys_table, "Failed to alloc mem for idt structure\n");
- goto fail;
- }
-
- idt->size = 0;
- idt->address = 0;
-
/*
* If the kernel isn't already loaded at the preferred load
* address, relocate it.
@@ -865,10 +854,8 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
desc->base2 = 0x00;
#endif /* CONFIG_X86_64 */
- asm volatile ("lidt %0" : : "m" (*idt));
- asm volatile ("lgdt %0" : : "m" (*gdt));
-
asm volatile("cli");
+ asm volatile ("lgdt %0" : : "m" (*gdt));
return boot_params;
fail:
--
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