From: David Woodhouse <d...@amazon.co.uk>
Reduce the window during which exceptions are unhandled, by leaving the
GDT/IDT in place all the way into the relocate_kernel() function, until
the moment that %cr3 gets replaced.
Signed-off-by: David Woodhouse <d...@amazon.co.uk>
---
arch/x86/kernel/machine_kexec_64.c | 10 ++--------
arch/x86/kernel/relocate_kernel_64.S | 9 +++++++--
2 files changed, 9 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kernel/machine_kexec_64.c
b/arch/x86/kernel/machine_kexec_64.c
index ecb0da54abd1..949c9e4bfad2 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -434,16 +434,10 @@ void __nocfi machine_kexec(struct kimage *image)
* with from a table in memory. At no other time is the
* descriptor table in memory accessed.
*
- * I take advantage of this here by force loading the
- * segments, before I zap the gdt with an invalid value.
+ * Take advantage of this here by force loading the segments,
+ * before the GDT is zapped with an invalid value.
*/
load_segments();
- /*
- * The gdt & idt are now invalid.
- * If you want to load them you must set up your own idt & gdt.
- */
- native_idt_invalidate();
- native_gdt_invalidate();
/* now call it */
image->start = relocate_kernel_ptr((unsigned long)image->head,
diff --git a/arch/x86/kernel/relocate_kernel_64.S
b/arch/x86/kernel/relocate_kernel_64.S
index 8808cfca6322..3062cb3efc44 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -79,8 +79,13 @@ SYM_CODE_START_NOALIGN(relocate_kernel)
pushq %r15
pushf
- /* zero out flags, and disable interrupts */
- pushq $0
+ /* Invalidate GDT/IDT, zero out flags */
+ pushq $0
+ pushq $0
+
+ lidt (%rsp)
+ lgdt (%rsp)
+ addq $8, %rsp
popfq
/* Switch to the identity mapped page tables */
--
2.48.1
