/* -----------------------------------------------------------------------
   *
   *   Copyright 2009-2014 Intel Corporation; author H. Peter Anvin
   *
   *   This file is part of the Linux kernel, and is made available under
   *   the terms of the GNU General Public License version 2 or (at your
   *   option) any later version; incorporated herein by reference.
   *
   * ----------------------------------------------------------------------- */
  
  /*
   * "Glove box" for BIOS calls.  Avoids the constant problems with BIOSes
   * touching registers they shouldn't be.
   */
  
  	.code16
  	.section ".inittext","ax"
  	.globl	intcall
  	.type	intcall, @function
  intcall:
  	/* Self-modify the INT instruction.  Ugly, but works. */
  	cmpb	%al, 3f
  	je	1f
  	movb	%al, 3f
  	jmp	1f		/* Synchronize pipeline */
  1:
  	/* Save state */
  	pushfl
  	pushw	%fs
  	pushw	%gs
  	pushal
  
  	/* Copy input state to stack frame */
  	subw	$44, %sp
  	movw	%dx, %si
  	movw	%sp, %di
  	movw	$11, %cx
  	rep; movsd
  
  	/* Pop full state from the stack */
  	popal
  	popw	%gs
  	popw	%fs
  	popw	%es
  	popw	%ds
  	popfl
  
  	/* Actual INT */
  	.byte	0xcd		/* INT opcode */
  3:	.byte	0
  
  	/* Push full state to the stack */
  	pushfl
  	pushw	%ds
  	pushw	%es
  	pushw	%fs
  	pushw	%gs
  	pushal
  
  	/* Re-establish C environment invariants */
  	cld
  	movzwl	%sp, %esp
  	movw	%cs, %ax
  	movw	%ax, %ds
  	movw	%ax, %es
  
  	/* Copy output state from stack frame */
  	movw	68(%esp), %di	/* Original %cx == 3rd argument */
  	andw	%di, %di
  	jz	4f
  	movw	%sp, %si
  	movw	$11, %cx
  	rep; movsd
  4:	addw	$44, %sp
  
  	/* Restore state and return */
  	popal
  	popw	%gs
  	popw	%fs
  	popfl
  	retl
  	.size	intcall, .-intcall