aboutsummaryrefslogtreecommitdiff
path: root/arch/x86/boot/pmjump.S
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/boot/pmjump.S')
-rw-r--r--arch/x86/boot/pmjump.S54
1 files changed, 41 insertions, 13 deletions
diff --git a/arch/x86/boot/pmjump.S b/arch/x86/boot/pmjump.S
index fa6bed1fac1..f5402d51f7c 100644
--- a/arch/x86/boot/pmjump.S
+++ b/arch/x86/boot/pmjump.S
@@ -15,6 +15,7 @@
*/
#include <asm/boot.h>
+#include <asm/processor-flags.h>
#include <asm/segment.h>
.text
@@ -29,28 +30,55 @@
*/
protected_mode_jump:
movl %edx, %esi # Pointer to boot_params table
- movl %eax, 2f # Patch ljmpl instruction
+
+ xorl %ebx, %ebx
+ movw %cs, %bx
+ shll $4, %ebx
+ addl %ebx, 2f
movw $__BOOT_DS, %cx
- xorl %ebx, %ebx # Per the 32-bit boot protocol
- xorl %ebp, %ebp # Per the 32-bit boot protocol
- xorl %edi, %edi # Per the 32-bit boot protocol
+ movw $__BOOT_TSS, %di
movl %cr0, %edx
- orb $1, %dl # Protected mode (PE) bit
+ orb $X86_CR0_PE, %dl # Protected mode
movl %edx, %cr0
jmp 1f # Short jump to serialize on 386/486
1:
- movw %cx, %ds
- movw %cx, %es
- movw %cx, %fs
- movw %cx, %gs
- movw %cx, %ss
-
- # Jump to the 32-bit entrypoint
+ # Transition to 32-bit mode
.byte 0x66, 0xea # ljmpl opcode
-2: .long 0 # offset
+2: .long in_pm32 # offset
.word __BOOT_CS # segment
.size protected_mode_jump, .-protected_mode_jump
+
+ .code32
+ .type in_pm32, @function
+in_pm32:
+ # Set up data segments for flat 32-bit mode
+ movl %ecx, %ds
+ movl %ecx, %es
+ movl %ecx, %fs
+ movl %ecx, %gs
+ movl %ecx, %ss
+ # The 32-bit code sets up its own stack, but this way we do have
+ # a valid stack if some debugging hack wants to use it.
+ addl %ebx, %esp
+
+ # Set up TR to make Intel VT happy
+ ltr %di
+
+ # Clear registers to allow for future extensions to the
+ # 32-bit boot protocol
+ xorl %ecx, %ecx
+ xorl %edx, %edx
+ xorl %ebx, %ebx
+ xorl %ebp, %ebp
+ xorl %edi, %edi
+
+ # Set up LDTR to make Intel VT happy
+ lldt %cx
+
+ jmpl *%eax # Jump to the 32-bit entrypoint
+
+ .size in_pm32, .-in_pm32