1*4882a593Smuzhiyun/* SPDX-License-Identifier: GPL-2.0-or-later */ 2*4882a593Smuzhiyun/* ----------------------------------------------------------------------- 3*4882a593Smuzhiyun * 4*4882a593Smuzhiyun * Copyright 2009-2014 Intel Corporation; author H. Peter Anvin 5*4882a593Smuzhiyun * 6*4882a593Smuzhiyun * ----------------------------------------------------------------------- */ 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun/* 9*4882a593Smuzhiyun * "Glove box" for BIOS calls. Avoids the constant problems with BIOSes 10*4882a593Smuzhiyun * touching registers they shouldn't be. 11*4882a593Smuzhiyun */ 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun .code16 14*4882a593Smuzhiyun .section ".inittext","ax" 15*4882a593Smuzhiyun .globl intcall 16*4882a593Smuzhiyun .type intcall, @function 17*4882a593Smuzhiyunintcall: 18*4882a593Smuzhiyun /* Self-modify the INT instruction. Ugly, but works. */ 19*4882a593Smuzhiyun cmpb %al, 3f 20*4882a593Smuzhiyun je 1f 21*4882a593Smuzhiyun movb %al, 3f 22*4882a593Smuzhiyun jmp 1f /* Synchronize pipeline */ 23*4882a593Smuzhiyun1: 24*4882a593Smuzhiyun /* Save state */ 25*4882a593Smuzhiyun pushfl 26*4882a593Smuzhiyun pushw %fs 27*4882a593Smuzhiyun pushw %gs 28*4882a593Smuzhiyun pushal 29*4882a593Smuzhiyun 30*4882a593Smuzhiyun /* Copy input state to stack frame */ 31*4882a593Smuzhiyun subw $44, %sp 32*4882a593Smuzhiyun movw %dx, %si 33*4882a593Smuzhiyun movw %sp, %di 34*4882a593Smuzhiyun movw $11, %cx 35*4882a593Smuzhiyun rep; movsd 36*4882a593Smuzhiyun 37*4882a593Smuzhiyun /* Pop full state from the stack */ 38*4882a593Smuzhiyun popal 39*4882a593Smuzhiyun popw %gs 40*4882a593Smuzhiyun popw %fs 41*4882a593Smuzhiyun popw %es 42*4882a593Smuzhiyun popw %ds 43*4882a593Smuzhiyun popfl 44*4882a593Smuzhiyun 45*4882a593Smuzhiyun /* Actual INT */ 46*4882a593Smuzhiyun .byte 0xcd /* INT opcode */ 47*4882a593Smuzhiyun3: .byte 0 48*4882a593Smuzhiyun 49*4882a593Smuzhiyun /* Push full state to the stack */ 50*4882a593Smuzhiyun pushfl 51*4882a593Smuzhiyun pushw %ds 52*4882a593Smuzhiyun pushw %es 53*4882a593Smuzhiyun pushw %fs 54*4882a593Smuzhiyun pushw %gs 55*4882a593Smuzhiyun pushal 56*4882a593Smuzhiyun 57*4882a593Smuzhiyun /* Re-establish C environment invariants */ 58*4882a593Smuzhiyun cld 59*4882a593Smuzhiyun movzwl %sp, %esp 60*4882a593Smuzhiyun movw %cs, %ax 61*4882a593Smuzhiyun movw %ax, %ds 62*4882a593Smuzhiyun movw %ax, %es 63*4882a593Smuzhiyun 64*4882a593Smuzhiyun /* Copy output state from stack frame */ 65*4882a593Smuzhiyun movw 68(%esp), %di /* Original %cx == 3rd argument */ 66*4882a593Smuzhiyun andw %di, %di 67*4882a593Smuzhiyun jz 4f 68*4882a593Smuzhiyun movw %sp, %si 69*4882a593Smuzhiyun movw $11, %cx 70*4882a593Smuzhiyun rep; movsd 71*4882a593Smuzhiyun4: addw $44, %sp 72*4882a593Smuzhiyun 73*4882a593Smuzhiyun /* Restore state and return */ 74*4882a593Smuzhiyun popal 75*4882a593Smuzhiyun popw %gs 76*4882a593Smuzhiyun popw %fs 77*4882a593Smuzhiyun popfl 78*4882a593Smuzhiyun retl 79*4882a593Smuzhiyun .size intcall, .-intcall 80