/*
   * ACPI wakeup real mode startup stub
   */
  #include <linux/linkage.h>
  #include <asm/segment.h>
  #include <asm/msr-index.h>
  #include <asm/page_types.h>
  #include <asm/pgtable_types.h>
  #include <asm/processor-flags.h>
  #include "realmode.h"
  #include "wakeup.h"
  
  	.code16
  
  /* This should match the structure in wakeup.h */
  	.section ".data", "aw"
  
  	.balign	16
  GLOBAL(wakeup_header)
  	video_mode:	.short	0	/* Video mode number */
  	pmode_entry:	.long	0
  	pmode_cs:	.short	__KERNEL_CS
  	pmode_cr0:	.long	0	/* Saved %cr0 */
  	pmode_cr3:	.long	0	/* Saved %cr3 */
  	pmode_cr4:	.long	0	/* Saved %cr4 */
  	pmode_efer:	.quad	0	/* Saved EFER */
  	pmode_gdt:	.quad	0
  	pmode_misc_en:	.quad	0	/* Saved MISC_ENABLE MSR */
  	pmode_behavior:	.long	0	/* Wakeup behavior flags */
  	realmode_flags:	.long	0
  	real_magic:	.long	0
  	signature:	.long	WAKEUP_HEADER_SIGNATURE
  END(wakeup_header)
  
  	.text
  	.code16
  
  	.balign	16
  ENTRY(wakeup_start)
  	cli
  	cld
  
  	LJMPW_RM(3f)
  3:
  	/* Apparently some dimwit BIOS programmers don't know how to
  	   program a PM to RM transition, and we might end up here with
  	   junk in the data segment descriptor registers.  The only way
  	   to repair that is to go into PM and fix it ourselves... */
  	movw	$16, %cx
  	lgdtl	%cs:wakeup_gdt
  	movl	%cr0, %eax
  	orb	$X86_CR0_PE, %al
  	movl	%eax, %cr0
  	ljmpw	$8, $2f
  2:
  	movw	%cx, %ds
  	movw	%cx, %es
  	movw	%cx, %ss
  	movw	%cx, %fs
  	movw	%cx, %gs
  
  	andb	$~X86_CR0_PE, %al
  	movl	%eax, %cr0
  	LJMPW_RM(3f)
  3:
  	/* Set up segments */
  	movw	%cs, %ax
  	movw	%ax, %ss
  	movl	$rm_stack_end, %esp
  	movw	%ax, %ds
  	movw	%ax, %es
  	movw	%ax, %fs
  	movw	%ax, %gs
  
  	lidtl	wakeup_idt
  
  	/* Clear the EFLAGS */
  	pushl $0
  	popfl
  
  	/* Check header signature... */
  	movl	signature, %eax
  	cmpl	$WAKEUP_HEADER_SIGNATURE, %eax
  	jne	bogus_real_magic
  
  	/* Check we really have everything... */
  	movl	end_signature, %eax
  	cmpl	$REALMODE_END_SIGNATURE, %eax
  	jne	bogus_real_magic
  
  	/* Call the C code */
  	calll	main
  
  	/* Restore MISC_ENABLE before entering protected mode, in case
  	   BIOS decided to clear XD_DISABLE during S3. */
  	movl	pmode_behavior, %edi
  	btl	$WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE, %edi
  	jnc	1f
  
  	movl	pmode_misc_en, %eax
  	movl	pmode_misc_en + 4, %edx
  	movl	$MSR_IA32_MISC_ENABLE, %ecx
  	wrmsr
  1:
  
  	/* Do any other stuff... */
  
  #ifndef CONFIG_64BIT
  	/* This could also be done in C code... */
  	movl	pmode_cr3, %eax
  	movl	%eax, %cr3
  
  	btl	$WAKEUP_BEHAVIOR_RESTORE_CR4, %edi
  	jnc	1f
  	movl	pmode_cr4, %eax
  	movl	%eax, %cr4
  1:
  	btl	$WAKEUP_BEHAVIOR_RESTORE_EFER, %edi
  	jnc	1f
  	movl	pmode_efer, %eax
  	movl	pmode_efer + 4, %edx
  	movl	$MSR_EFER, %ecx
  	wrmsr
  1:
  
  	lgdtl	pmode_gdt
  
  	/* This really couldn't... */
  	movl	pmode_entry, %eax
  	movl	pmode_cr0, %ecx
  	movl	%ecx, %cr0
  	ljmpl	$__KERNEL_CS, $pa_startup_32
  	/* -> jmp *%eax in trampoline_32.S */
  #else
  	jmp	trampoline_start
  #endif
  
  bogus_real_magic:
  1:
  	hlt
  	jmp	1b
  
  	.section ".rodata","a"
  
  	/*
  	 * Set up the wakeup GDT.  We set these up as Big Real Mode,
  	 * that is, with limits set to 4 GB.  At least the Lenovo
  	 * Thinkpad X61 is known to need this for the video BIOS
  	 * initialization quirk to work; this is likely to also
  	 * be the case for other laptops or integrated video devices.
  	 */
  
  	.balign	16
  GLOBAL(wakeup_gdt)
  	.word	3*8-1		/* Self-descriptor */
  	.long	pa_wakeup_gdt
  	.word	0
  
  	.word	0xffff		/* 16-bit code segment @ real_mode_base */
  	.long	0x9b000000 + pa_real_mode_base
  	.word	0x008f		/* big real mode */
  
  	.word	0xffff		/* 16-bit data segment @ real_mode_base */
  	.long	0x93000000 + pa_real_mode_base
  	.word	0x008f		/* big real mode */
  END(wakeup_gdt)
  
  	.section ".rodata","a"
  	.balign	8
  
  	/* This is the standard real-mode IDT */
  	.balign	16
  GLOBAL(wakeup_idt)
  	.word	0xffff		/* limit */
  	.long	0		/* address */
  	.word	0
  END(wakeup_idt)