On Tue, Feb 11, 2020 at 5:53 AM Joerg Roedel <joro@xxxxxxxxxx> wrote: > > From: Joerg Roedel <jroedel@xxxxxxx> > > Handling exceptions during boot requires a working GDT. The kernel GDT > is not yet ready for use, so install a temporary boot GDT. > > Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> > --- > arch/x86/kernel/head_64.S | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S > index 4bbc770af632..5a3cde971cb7 100644 > --- a/arch/x86/kernel/head_64.S > +++ b/arch/x86/kernel/head_64.S > @@ -72,6 +72,20 @@ SYM_CODE_START_NOALIGN(startup_64) > /* Set up the stack for verify_cpu(), similar to initial_stack below */ > leaq (__end_init_task - SIZEOF_PTREGS)(%rip), %rsp > > + /* Setup boot GDT descriptor and load boot GDT */ > + leaq boot_gdt(%rip), %rax > + movq %rax, boot_gdt_base(%rip) > + lgdt boot_gdt_descr(%rip) > + > + /* GDT loaded - switch to __KERNEL_CS so IRET works reliably */ > + pushq $__KERNEL_CS > + leaq .Lon_kernel_cs(%rip), %rax > + pushq %rax > + lretq > + > +.Lon_kernel_cs: > + UNWIND_HINT_EMPTY I would suggest fixing at least SS as well.
