Commit-ID: 7beebaccd5083d61e975acb581bd528b9326e7c4 Gitweb: https://git.kernel.org/tip/7beebaccd5083d61e975acb581bd528b9326e7c4 Author: Kirill A. Shutemov <kirill.shute...@linux.intel.com> AuthorDate: Mon, 12 Mar 2018 13:02:43 +0300 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Mon, 12 Mar 2018 11:49:24 +0100
x86/boot/compressed/64: Make sure we have a 32-bit code segment 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.shute...@linux.intel.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Andy Lutomirski <l...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Borislav Petkov <b...@suse.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Cyrill Gorcunov <gorcu...@openvz.org> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Matthew Wilcox <wi...@infradead.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: linux...@kvack.org Link: http://lkml.kernel.org/r/20180312100246.89175-2-kirill.shute...@linux.intel.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/boot/compressed/head_64.S | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index c813cb004056..f0c3a2f7e528 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -313,6 +313,11 @@ ENTRY(startup_64) * 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. @@ -547,6 +552,11 @@ no_longmode: #include "../../kernel/verify_cpu.S" .data +gdt64: + .word gdt_end - gdt + .long 0 + .word 0 + .quad 0 gdt: .word gdt_end - gdt .long gdt
