| Thomas Gleixner | d691005 | 2019-05-22 09:51:29 +0200 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| H. Peter Anvin | 7a734e7 | 2009-04-01 18:08:28 -0700 | [diff] [blame] | 2 | /* ----------------------------------------------------------------------- |
| 3 | * |
| H. Peter Anvin | 6f34152 | 2014-01-04 14:29:08 -0800 | [diff] [blame] | 4 | * Copyright 2009-2014 Intel Corporation; author H. Peter Anvin |
| H. Peter Anvin | 7a734e7 | 2009-04-01 18:08:28 -0700 | [diff] [blame] | 5 | * |
| H. Peter Anvin | 7a734e7 | 2009-04-01 18:08:28 -0700 | [diff] [blame] | 6 | * ----------------------------------------------------------------------- */ |
| 7 | |
| 8 | /* |
| 9 | * "Glove box" for BIOS calls. Avoids the constant problems with BIOSes |
| H. Peter Anvin | cf9972a9 | 2009-04-11 22:24:05 -0700 | [diff] [blame] | 10 | * touching registers they shouldn't be. |
| H. Peter Anvin | 7a734e7 | 2009-04-01 18:08:28 -0700 | [diff] [blame] | 11 | */ |
| 12 | |
| David Woodhouse | e24df92 | 2014-01-03 22:30:42 +0000 | [diff] [blame] | 13 | .code16 |
| H. Peter Anvin | 6f34152 | 2014-01-04 14:29:08 -0800 | [diff] [blame] | 14 | .section ".inittext","ax" |
| H. Peter Anvin | 7a734e7 | 2009-04-01 18:08:28 -0700 | [diff] [blame] | 15 | .globl intcall |
| 16 | .type intcall, @function |
| 17 | intcall: |
| 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 */ |
| 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; movsd |
| 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 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; movsd |
| 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 |
