Commit-ID: 7beebaccd5083d61e975acb581bd528b9326e7c4 Gitweb: https://git.kernel.org/tip/7beebaccd5083d61e975acb581bd528b9326e7c4 Author: Kirill A. Shutemov <[email protected]> AuthorDate: Mon, 12 Mar 2018 13:02:43 +0300 Committer: Ingo Molnar <[email protected]> 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 <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Cyrill Gorcunov <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- 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
