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- /* -----------------------------------------------------------------------
- *
- * 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
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