1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2/* ----------------------------------------------------------------------- 3 * 4 * Copyright 2009-2014 Intel Corporation; author H. Peter Anvin 5 * 6 * ----------------------------------------------------------------------- */ 7 8/* 9 * "Glove box" for BIOS calls. Avoids the constant problems with BIOSes 10 * touching registers they shouldn't be. 11 */ 12 13 .code16 14 .section ".inittext","ax" 15 .globl intcall 16 .type intcall, @function 17intcall: 18 /* Self-modify the INT instruction. Ugly, but works. */ 19 cmpb %al, 3f 20 je 1f 21 movb %al, 3f 22 jmp 1f /* Synchronize pipeline */ 231: 24 /* Save state */ 25 pushfl 26 pushw %fs 27 pushw %gs 28 pushal 29 30 /* Copy input state to stack frame */ 31 subw $44, %sp 32 movw %dx, %si 33 movw %sp, %di 34 movw $11, %cx 35 rep; movsl 36 37 /* Pop full state from the stack */ 38 popal 39 popw %gs 40 popw %fs 41 popw %es 42 popw %ds 43 popfl 44 45 /* Actual INT */ 46 .byte 0xcd /* INT opcode */ 473: .byte 0 48 49 /* Push full state to the stack */ 50 pushfl 51 pushw %ds 52 pushw %es 53 pushw %fs 54 pushw %gs 55 pushal 56 57 /* Re-establish C environment invariants */ 58 cld 59 movzwl %sp, %esp 60 movw %cs, %ax 61 movw %ax, %ds 62 movw %ax, %es 63 64 /* Copy output state from stack frame */ 65 movw 68(%esp), %di /* Original %cx == 3rd argument */ 66 andw %di, %di 67 jz 4f 68 movw %sp, %si 69 movw $11, %cx 70 rep; movsl 714: addw $44, %sp 72 73 /* Restore state and return */ 74 popal 75 popw %gs 76 popw %fs 77 popfl 78 retl 79 .size intcall, .-intcall 80