[PATCH 4/8] efi/x86: Only setup the GDT for 32-bit kernel

[Arvind Sankar <nivedita@xxxxxxxxxxxx>]

On a 64-bit kernel, the next function to execute after efi_main returns
is startup_64, which sets up its own GDT, so setting one up in efi_main
is unnecessary.

Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
---
 arch/x86/boot/compressed/eboot.c | 60 ++++++--------------------------
 1 file changed, 10 insertions(+), 50 deletions(-)

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 066125a18391..a72cfda91d7e 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -346,6 +346,7 @@ void setup_graphics(struct boot_params *boot_params)
 
 static efi_status_t setup_gdt(struct desc_ptr *gdt)
 {
+#ifdef CONFIG_X86_32
 	efi_status_t status;
 	struct desc_struct *desc;
 
@@ -361,30 +362,10 @@ static efi_status_t setup_gdt(struct desc_ptr *gdt)
 
 	/* The first GDT is a dummy. */
 	desc++;
+	/* Second entry is unused on 32-bit */
+	desc++;
 
-	if (IS_ENABLED(CONFIG_X86_64)) {
-		/* __KERNEL32_CS */
-		desc->limit0	= 0xffff;
-		desc->base0	= 0x0000;
-		desc->base1	= 0x0000;
-		desc->type	= SEG_TYPE_CODE | SEG_TYPE_EXEC_READ;
-		desc->s		= DESC_TYPE_CODE_DATA;
-		desc->dpl	= 0;
-		desc->p		= 1;
-		desc->limit1	= 0xf;
-		desc->avl	= 0;
-		desc->l		= 0;
-		desc->d		= SEG_OP_SIZE_32BIT;
-		desc->g		= SEG_GRANULARITY_4KB;
-		desc->base2	= 0x00;
-
-		desc++;
-	} else {
-		/* Second entry is unused on 32-bit */
-		desc++;
-	}
-
-	/* __KERNEL_CS */
+	/* __BOOT_CS */
 	desc->limit0	= 0xffff;
 	desc->base0	= 0x0000;
 	desc->base1	= 0x0000;
@@ -394,19 +375,13 @@ static efi_status_t setup_gdt(struct desc_ptr *gdt)
 	desc->p		= 1;
 	desc->limit1	= 0xf;
 	desc->avl	= 0;
-
-	if (IS_ENABLED(CONFIG_X86_64)) {
-		desc->l = 1;
-		desc->d = 0;
-	} else {
-		desc->l = 0;
-		desc->d = SEG_OP_SIZE_32BIT;
-	}
+	desc->l		= 0;
+	desc->d		= SEG_OP_SIZE_32BIT;
 	desc->g		= SEG_GRANULARITY_4KB;
 	desc->base2	= 0x00;
 	desc++;
 
-	/* __KERNEL_DS */
+	/* __BOOT_DS */
 	desc->limit0	= 0xffff;
 	desc->base0	= 0x0000;
 	desc->base1	= 0x0000;
@@ -422,23 +397,7 @@ static efi_status_t setup_gdt(struct desc_ptr *gdt)
 	desc->base2	= 0x00;
 	desc++;
 
-	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->limit1	= 0x0;
-		desc->avl	= 0;
-		desc->l		= 0;
-		desc->d		= 0;
-		desc->g		= SEG_GRANULARITY_4KB;
-		desc->base2	= 0x00;
-		desc++;
-	}
+#endif /* CONFIG_X86_32 */
 
 	return EFI_SUCCESS;
 }
@@ -883,7 +842,8 @@ struct boot_params *efi_main(efi_handle_t handle,
 	}
 
 	raw_local_irq_disable();
-	native_load_gdt(&gdt);
+	if (IS_ENABLED(CONFIG_X86_32))
+		native_load_gdt(&gdt);
 
 	return boot_params;
 fail:
-- 
2.24.1