[PATCH v7 30/72] x86/head/64: Load GDT after switch to virtual addresses
From: Joerg Roedel <joro@8bytes.org>
Date: 2020-09-07 17:38:02
Also in:
kvm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Joerg Roedel <redacted> Load the GDT right after switching to virtual addresses to make sure there is a defined GDT for exception handling. Signed-off-by: Joerg Roedel <redacted> Reviewed-by: Kees Cook <redacted> --- arch/x86/kernel/head_64.S | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 2b2e91627221..03b03f266dc1 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S@@ -158,6 +158,14 @@ SYM_CODE_START(secondary_startup_64) 1: UNWIND_HINT_EMPTY + /* + * We must switch to a new descriptor in kernel space for the GDT + * because soon the kernel won't have access anymore to the userspace + * addresses where we're currently running on. We have to do that here + * because in 32bit we couldn't load a 64bit linear address. + */ + lgdt early_gdt_descr(%rip) + /* Check if nx is implemented */ movl $0x80000001, %eax cpuid
@@ -185,14 +193,6 @@ SYM_CODE_START(secondary_startup_64) pushq $0 popfq - /* - * We must switch to a new descriptor in kernel space for the GDT - * because soon the kernel won't have access anymore to the userspace - * addresses where we're currently running on. We have to do that here - * because in 32bit we couldn't load a 64bit linear address. - */ - lgdt early_gdt_descr(%rip) - /* set up data segments */ xorl %eax,%eax movl %eax,%ds
--
2.28.0
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