x86, realmode: read cr4 and EFER from kernel for 64-bit trampoline

This patch changes 64-bit trampoline so that CR4 and
EFER are provided by the kernel instead of using fixed
values.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-24-git-send-email-jarkko.sakkinen@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

3 files changed, 27 insertions, 25 deletions

diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S
index b4c3263..4612d538 100644
--- a/arch/x86/realmode/rm/header.S
+++ b/arch/x86/realmode/rm/header.S
@@ -9,6 +9,7 @@
 
 	.section ".header", "a"
 
+	.balign	16
 GLOBAL(real_mode_header)
 	.long	pa_text_start
 	.long	pa_ro_end
diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
index 3f72932..66e26f0 100644
--- a/arch/x86/realmode/rm/trampoline_64.S
+++ b/arch/x86/realmode/rm/trampoline_64.S
@@ -34,9 +34,9 @@
 #include "realmode.h"
 
 	.text
-	.balign PAGE_SIZE
 	.code16
 
+	.balign	PAGE_SIZE
 ENTRY(trampoline_start)
 	cli			# We should be safe anyway
 	wbinvd
@@ -65,8 +65,8 @@ ENTRY(trampoline_start)
 	 * to 32 bit.
 	 */
 
-	lidtl	tidt	# load idt with 0, 0
-	lgdtl	tgdt	# load gdt with whatever is appropriate
+	lidtl	tr_idt	# load idt with 0, 0
+	lgdtl	tr_gdt	# load gdt with whatever is appropriate
 
 	movw	$__KERNEL_DS, %dx	# Data segment descriptor
 
@@ -93,16 +93,17 @@ ENTRY(startup_32)
 	movl	%edx, %fs
 	movl	%edx, %gs
 
-	movl	$X86_CR4_PAE, %eax
+	movl	pa_tr_cr4, %eax
 	movl	%eax, %cr4		# Enable PAE mode
 
 	# Setup trampoline 4 level pagetables
 	movl	$pa_trampoline_pgd, %eax
 	movl	%eax, %cr3
 
+	# Set up EFER
+	movl	pa_tr_efer, %eax
+	movl	pa_tr_efer + 4, %edx
 	movl	$MSR_EFER, %ecx
-	movl	$((1 << _EFER_LME) | (1 << _EFER_NX)), %eax	# Enable Long Mode
-	xorl	%edx, %edx
 	wrmsr
 
 	# Enable paging and in turn activate Long Mode
@@ -124,23 +125,4 @@ ENTRY(startup_64)
 	# Now jump into the kernel using virtual addresses
 	jmpq	*tr_start(%rip)
 
-	.section ".rodata","a"
-	.balign	16
-tidt:
-	.word	0			# idt limit = 0
-	.word	0, 0			# idt base = 0L
-
-	# Duplicate the global descriptor table
-	# so the kernel can live anywhere
-	.balign 16
-	.globl tgdt
-tgdt:
-	.short	tgdt_end - tgdt - 1	# gdt limit
-	.long	pa_tgdt
-	.short	0
-	.quad	0x00cf9b000000ffff	# __KERNEL32_CS
-	.quad	0x00af9b000000ffff	# __KERNEL_CS
-	.quad	0x00cf93000000ffff	# __KERNEL_DS
-tgdt_end:
-
 #include "trampoline_common.S"
diff --git a/arch/x86/realmode/rm/trampoline_common.S b/arch/x86/realmode/rm/trampoline_common.S
index c3f951c..cac444b 100644
--- a/arch/x86/realmode/rm/trampoline_common.S
+++ b/arch/x86/realmode/rm/trampoline_common.S
@@ -1,5 +1,20 @@
 	.section ".rodata","a"
 
+#ifdef CONFIG_X86_64
+	# Duplicate the global descriptor table
+	# so the kernel can live anywhere
+	.balign	16
+	.globl tr_gdt
+tr_gdt:
+	.short	tr_gdt_end - tr_gdt - 1	# gdt limit
+	.long	pa_tr_gdt
+	.short	0
+	.quad	0x00cf9b000000ffff	# __KERNEL32_CS
+	.quad	0x00af9b000000ffff	# __KERNEL_CS
+	.quad	0x00cf93000000ffff	# __KERNEL_DS
+tr_gdt_end:
+#endif
+
 	.balign	4
 tr_idt: .fill 1, 6, 0
 
@@ -8,12 +23,16 @@ tr_idt: .fill 1, 6, 0
 	.balign	4
 GLOBAL(trampoline_status)	.space	4
 
+	.balign	8
 GLOBAL(trampoline_header)
 #ifdef CONFIG_X86_32
 	tr_start:		.space	4
+	tr_gdt_pad:		.space	2
 	tr_gdt:			.space	6
 #else
 	tr_start:		.space	8
+	GLOBAL(tr_cr4)		.space	4
+	GLOBAL(tr_efer)		.space	8
 #endif
 END(trampoline_header)