The following commit has been merged into the x86/seves branch of tip: Commit-ID: e04b88336360e101329add0c05e5cb1cebae64fd Gitweb: https://git.kernel.org/tip/e04b88336360e101329add0c05e5cb1cebae64fd Author: Joerg Roedel <jroedel@xxxxxxx> AuthorDate: Mon, 07 Sep 2020 15:15:31 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Mon, 07 Sep 2020 21:35:54 +02:00 x86/head/64: Load GDT after switch to virtual addresses 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 <jroedel@xxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20200907131613.12703-31-joro@xxxxxxxxxx --- 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 2b2e916..03b03f2 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
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