When kernel starts in 64-bit mode we inherit the GDT from the bootloader.
It may cause a problem if the GDT doesn't have a 32-bit code segment
where we expect it to be.
Load our own GDT with known segments.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180312100246.89175-2-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
* first.
*/
+ /* Make sure we have GDT with 32-bit code segment */
+ leaq gdt(%rip), %rax
+ movq %rax, gdt64+2(%rip)
+ lgdt gdt64(%rip)
+
/*
* paging_prepare() sets up the trampoline and checks if we need to
* enable 5-level paging.
#include "../../kernel/verify_cpu.S"
.data
+gdt64:
+ .word gdt_end - gdt
+ .long 0
+ .word 0
+ .quad 0
gdt:
.word gdt_end - gdt
.long gdt