/* ----------------------------------------------------------------------- * * 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 |