1 /* SPDX-License-Identifier: GPL-2.0-or-later *
2 /* -------------------------------------------
3 *
4 * Copyright 2009-2014 Intel Corporation; au
5 *
6 * -------------------------------------------
7
8 /*
9 * "Glove box" for BIOS calls. Avoids the con
10 * touching registers they shouldn't be.
11 */
12
13 .code16
14 .section ".inittext","ax"
15 .globl intcall
16 .type intcall, @function
17 intcall:
18 /* Self-modify the INT instruction. U
19 cmpb %al, 3f
20 je 1f
21 movb %al, 3f
22 jmp 1f /* Synchronize
23 1:
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
47 3: .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 invarian
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 %c
66 andw %di, %di
67 jz 4f
68 movw %sp, %si
69 movw $11, %cx
70 rep; movsl
71 4: 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
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