x86/boot/efi: Cleanup initialization of GDT entries

This is preparation for following patches without changing semantics of the
code.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
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: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170606113133.22974-4-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index cbf4b87f55b9e9da244754d343401b5374dd49d1..1d5093d1f319bb71a9310ada7b548d87fe791a51 100644 (file)
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -1049,6 +1049,7 @@ struct boot_params *efi_main(struct efi_config *c,
        /* The first GDT is a dummy and the second is unused. */
        desc += 2;
 
+       /* __KERNEL_CS */
        desc->limit0 = 0xffff;
        desc->base0 = 0x0000;
        desc->base1 = 0x0000;
@@ -1062,8 +1063,9 @@ struct boot_params *efi_main(struct efi_config *c,
        desc->d = SEG_OP_SIZE_32BIT;
        desc->g = SEG_GRANULARITY_4KB;
        desc->base2 = 0x00;
-
        desc++;
+
+       /* __KERNEL_DS */
        desc->limit0 = 0xffff;
        desc->base0 = 0x0000;
        desc->base1 = 0x0000;
@@ -1077,24 +1079,25 @@ struct boot_params *efi_main(struct efi_config *c,
        desc->d = SEG_OP_SIZE_32BIT;
        desc->g = SEG_GRANULARITY_4KB;
        desc->base2 = 0x00;
-
-#ifdef CONFIG_X86_64
-       /* Task segment value */
        desc++;
-       desc->limit0 = 0x0000;
-       desc->base0 = 0x0000;
-       desc->base1 = 0x0000;
-       desc->type = SEG_TYPE_TSS;
-       desc->s = 0;
-       desc->dpl = 0;
-       desc->p = 1;
-       desc->limit = 0x0;
-       desc->avl = 0;
-       desc->l = 0;
-       desc->d = 0;
-       desc->g = SEG_GRANULARITY_4KB;
-       desc->base2 = 0x00;
-#endif /* CONFIG_X86_64 */
+
+       if (IS_ENABLED(CONFIG_X86_64)) {
+               /* Task segment value */
+               desc->limit0 = 0x0000;
+               desc->base0 = 0x0000;
+               desc->base1 = 0x0000;
+               desc->type = SEG_TYPE_TSS;
+               desc->s = 0;
+               desc->dpl = 0;
+               desc->p = 1;
+               desc->limit = 0x0;
+               desc->avl = 0;
+               desc->l = 0;
+               desc->d = 0;
+               desc->g = SEG_GRANULARITY_4KB;
+               desc->base2 = 0x00;
+               desc++;
+       }
 
        asm volatile("cli");
        asm volatile ("lgdt %0" : : "m" (*gdt));