arch/x86/gdt: Work around assembler bug

The GDT loading did work fine on x86_64 a few months ago, but today it
only works in QEMU, but not on real hardware or KVM-enabled QEMU. This
might be related to toolchain changes.

Use 64bit GDT loading on x86_64 and force the assembler to generate a
64bit address load on the GDT. This will make sure no 32bit (signed)
displacement op is being generated, which points to the wrong address
in longmode.

Verified using readelf and made sure no R_X86_64_32S relocation symbol
is emitted. Disassembled the romstage ELF and made sure the GDT address
is 64bit in size.

Tested on QEMU and KVM-enabled QEMU: Doesn't crash any more on KVM.

Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Change-Id: Ia824f90d9611e6e8db09bd62a05e6f990581f09a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43136
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

0 files changed, 0 insertions, 0 deletions