1 /*
2 * Copyright (C) 2008 Daniel Verkamp <daniel@drv.nu>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18
19 /**
20 * @file SYSLINUX COMBOOT API
21 *
22 */
23
24 FILE_LICENCE ( GPL2_OR_LATER );
25
26 #include <errno.h>
27 #include <realmode.h>
28 #include <biosint.h>
29 #include <console.h>
30 #include <stdlib.h>
31 #include <comboot.h>
32 #include <bzimage.h>
33 #include <pxe_call.h>
34 #include <setjmp.h>
35 #include <string.h>
36 #include <gpxe/posix_io.h>
37 #include <gpxe/process.h>
38 #include <gpxe/serial.h>
39 #include <gpxe/init.h>
40 #include <gpxe/image.h>
41 #include <usr/imgmgmt.h>
42 #include "config/console.h"
43 #include "config/serial.h"
44
45 /** The "SYSLINUX" version string */
46 static char __data16_array ( syslinux_version, [] ) = "gPXE " VERSION;
47 #define syslinux_version __use_data16 ( syslinux_version )
48
49 /** The "SYSLINUX" copyright string */
50 static char __data16_array ( syslinux_copyright, [] ) = "http://etherboot.org";
51 #define syslinux_copyright __use_data16 ( syslinux_copyright )
52
53 static char __data16_array ( syslinux_configuration_file, [] ) = "";
54 #define syslinux_configuration_file __use_data16 ( syslinux_configuration_file )
55
56 /** Feature flags */
57 static uint8_t __data16 ( comboot_feature_flags ) = COMBOOT_FEATURE_IDLE_LOOP;
58 #define comboot_feature_flags __use_data16 ( comboot_feature_flags )
59
60 typedef union {
61 syslinux_pm_regs pm; syslinux_rm_regs rm;
62 } syslinux_regs;
63
64 /** Initial register values for INT 22h AX=1Ah and 1Bh */
65 static syslinux_regs __text16 ( comboot_initial_regs );
66 #define comboot_initial_regs __use_text16 ( comboot_initial_regs )
67
68 static struct segoff __text16 ( int20_vector );
69 #define int20_vector __use_text16 ( int20_vector )
70
71 static struct segoff __text16 ( int21_vector );
72 #define int21_vector __use_text16 ( int21_vector )
73
74 static struct segoff __text16 ( int22_vector );
75 #define int22_vector __use_text16 ( int22_vector )
76
77 extern void int20_wrapper ( void );
78 extern void int21_wrapper ( void );
79 extern void int22_wrapper ( void );
80
81 /* setjmp/longjmp context buffer used to return after loading an image */
82 rmjmp_buf comboot_return;
83
84 /* Replacement image when exiting with COMBOOT_EXIT_RUN_KERNEL */
85 struct image *comboot_replacement_image;
86
87 /* Mode flags set by INT 22h AX=0017h */
88 static uint16_t comboot_graphics_mode = 0;
89
90
91 /**
92 * Print a string with a particular terminator
93 */
print_user_string(unsigned int segment,unsigned int offset,char terminator)94 static void print_user_string ( unsigned int segment, unsigned int offset, char terminator ) {
95 int i = 0;
96 char c;
97 userptr_t str = real_to_user ( segment, offset );
98 for ( ; ; ) {
99 copy_from_user ( &c, str, i, 1 );
100 if ( c == terminator ) break;
101 putchar ( c );
102 i++;
103 }
104 }
105
106
107 /**
108 * Perform a series of memory copies from a list in low memory
109 */
shuffle(unsigned int list_segment,unsigned int list_offset,unsigned int count)110 static void shuffle ( unsigned int list_segment, unsigned int list_offset, unsigned int count )
111 {
112 comboot_shuffle_descriptor shuf[COMBOOT_MAX_SHUFFLE_DESCRIPTORS];
113 unsigned int i;
114
115 /* Copy shuffle descriptor list so it doesn't get overwritten */
116 copy_from_user ( shuf, real_to_user ( list_segment, list_offset ), 0,
117 count * sizeof( comboot_shuffle_descriptor ) );
118
119 /* Do the copies */
120 for ( i = 0; i < count; i++ ) {
121 userptr_t src_u = phys_to_user ( shuf[ i ].src );
122 userptr_t dest_u = phys_to_user ( shuf[ i ].dest );
123
124 if ( shuf[ i ].src == 0xFFFFFFFF ) {
125 /* Fill with 0 instead of copying */
126 memset_user ( dest_u, 0, 0, shuf[ i ].len );
127 } else if ( shuf[ i ].dest == 0xFFFFFFFF ) {
128 /* Copy new list of descriptors */
129 count = shuf[ i ].len / sizeof( comboot_shuffle_descriptor );
130 assert ( count <= COMBOOT_MAX_SHUFFLE_DESCRIPTORS );
131 copy_from_user ( shuf, src_u, 0, shuf[ i ].len );
132 i = -1;
133 } else {
134 /* Regular copy */
135 memmove_user ( dest_u, 0, src_u, 0, shuf[ i ].len );
136 }
137 }
138 }
139
140
141 /**
142 * Set default text mode
143 */
comboot_force_text_mode(void)144 void comboot_force_text_mode ( void ) {
145 if ( comboot_graphics_mode & COMBOOT_VIDEO_VESA ) {
146 /* Set VGA mode 3 via VESA VBE mode set */
147 __asm__ __volatile__ (
148 REAL_CODE (
149 "mov $0x4F02, %%ax\n\t"
150 "mov $0x03, %%bx\n\t"
151 "int $0x10\n\t"
152 )
153 : : );
154 } else if ( comboot_graphics_mode & COMBOOT_VIDEO_GRAPHICS ) {
155 /* Set VGA mode 3 via standard VGA mode set */
156 __asm__ __volatile__ (
157 REAL_CODE (
158 "mov $0x03, %%ax\n\t"
159 "int $0x10\n\t"
160 )
161 : : );
162 }
163
164 comboot_graphics_mode = 0;
165 }
166
167
168 /**
169 * Fetch kernel and optional initrd
170 */
comboot_fetch_kernel(char * kernel_file,char * cmdline)171 static int comboot_fetch_kernel ( char *kernel_file, char *cmdline ) {
172 struct image *kernel = NULL;
173 struct image *initrd = NULL;
174 char *initrd_file;
175 int rc;
176
177 /* Find initrd= parameter, if any */
178 if ( ( initrd_file = strstr ( cmdline, "initrd=" ) ) != NULL ) {
179 char *initrd_end;
180
181 /* skip "initrd=" */
182 initrd_file += 7;
183
184 /* Find terminating space, if any, and replace with NUL */
185 initrd_end = strchr ( initrd_file, ' ' );
186 if ( initrd_end )
187 *initrd_end = '\0';
188
189 DBG ( "COMBOOT: fetching initrd '%s'\n", initrd_file );
190
191 /* Allocate and fetch initrd */
192 initrd = alloc_image();
193 if ( ! initrd ) {
194 DBG ( "COMBOOT: could not allocate initrd\n" );
195 rc = -ENOMEM;
196 goto out;
197 }
198 if ( ( rc = imgfetch ( initrd, initrd_file,
199 register_image ) ) != 0 ) {
200 DBG ( "COMBOOT: could not fetch initrd: %s\n",
201 strerror ( rc ) );
202 goto out;
203 }
204
205 /* Restore space after initrd name, if applicable */
206 if ( initrd_end )
207 *initrd_end = ' ';
208 }
209
210 DBG ( "COMBOOT: fetching kernel '%s'\n", kernel_file );
211
212 /* Allocate and fetch kernel */
213 kernel = alloc_image();
214 if ( ! kernel ) {
215 DBG ( "COMBOOT: could not allocate kernel\n" );
216 rc = -ENOMEM;
217 goto out;
218 }
219 if ( ( rc = imgfetch ( kernel, kernel_file,
220 register_image ) ) != 0 ) {
221 DBG ( "COMBOOT: could not fetch kernel: %s\n",
222 strerror ( rc ) );
223 goto out;
224 }
225 if ( ( rc = image_set_cmdline ( kernel, cmdline ) ) != 0 ) {
226 DBG ( "COMBOOT: could not set kernel command line: %s\n",
227 strerror ( rc ) );
228 goto out;
229 }
230
231 /* Store kernel as replacement image */
232 assert ( comboot_replacement_image == NULL );
233 comboot_replacement_image = image_get ( kernel );
234
235 out:
236 /* Drop image references unconditionally; either we want to
237 * discard them, or they have been registered and we should
238 * drop out local reference.
239 */
240 image_put ( kernel );
241 image_put ( initrd );
242 return rc;
243 }
244
245
246 /**
247 * Terminate program interrupt handler
248 */
int20(struct i386_all_regs * ix86 __unused)249 static __asmcall void int20 ( struct i386_all_regs *ix86 __unused ) {
250 rmlongjmp ( comboot_return, COMBOOT_EXIT );
251 }
252
253
254 /**
255 * DOS-compatible API
256 */
int21(struct i386_all_regs * ix86)257 static __asmcall void int21 ( struct i386_all_regs *ix86 ) {
258 ix86->flags |= CF;
259
260 switch ( ix86->regs.ah ) {
261 case 0x00:
262 case 0x4C: /* Terminate program */
263 rmlongjmp ( comboot_return, COMBOOT_EXIT );
264 break;
265
266 case 0x01: /* Get Key with Echo */
267 case 0x08: /* Get Key without Echo */
268 /* TODO: handle extended characters? */
269 ix86->regs.al = getchar( );
270
271 /* Enter */
272 if ( ix86->regs.al == 0x0A )
273 ix86->regs.al = 0x0D;
274
275 if ( ix86->regs.ah == 0x01 )
276 putchar ( ix86->regs.al );
277
278 ix86->flags &= ~CF;
279 break;
280
281 case 0x02: /* Write Character */
282 putchar ( ix86->regs.dl );
283 ix86->flags &= ~CF;
284 break;
285
286 case 0x04: /* Write Character to Serial Port */
287 serial_putc ( ix86->regs.dl );
288 ix86->flags &= ~CF;
289 break;
290
291 case 0x09: /* Write DOS String to Console */
292 print_user_string ( ix86->segs.ds, ix86->regs.dx, '$' );
293 ix86->flags &= ~CF;
294 break;
295
296 case 0x0B: /* Check Keyboard */
297 if ( iskey() )
298 ix86->regs.al = 0xFF;
299 else
300 ix86->regs.al = 0x00;
301
302 ix86->flags &= ~CF;
303 break;
304
305 case 0x30: /* Check DOS Version */
306 /* Bottom halves all 0; top halves spell "SYSLINUX" */
307 ix86->regs.eax = 0x59530000;
308 ix86->regs.ebx = 0x4C530000;
309 ix86->regs.ecx = 0x4E490000;
310 ix86->regs.edx = 0x58550000;
311 ix86->flags &= ~CF;
312 break;
313
314 default:
315 DBG ( "COMBOOT unknown int21 function %02x\n", ix86->regs.ah );
316 break;
317 }
318 }
319
320
321 /**
322 * SYSLINUX API
323 */
int22(struct i386_all_regs * ix86)324 static __asmcall void int22 ( struct i386_all_regs *ix86 ) {
325 ix86->flags |= CF;
326
327 switch ( ix86->regs.ax ) {
328 case 0x0001: /* Get Version */
329
330 /* Number of INT 22h API functions available */
331 ix86->regs.ax = 0x001D;
332
333 /* SYSLINUX version number */
334 ix86->regs.ch = 0; /* major */
335 ix86->regs.cl = 0; /* minor */
336
337 /* SYSLINUX derivative ID */
338 ix86->regs.dl = BZI_LOADER_TYPE_GPXE;
339
340 /* SYSLINUX version and copyright strings */
341 ix86->segs.es = rm_ds;
342 ix86->regs.si = ( ( unsigned ) __from_data16 ( syslinux_version ) );
343 ix86->regs.di = ( ( unsigned ) __from_data16 ( syslinux_copyright ) );
344
345 ix86->flags &= ~CF;
346 break;
347
348 case 0x0002: /* Write String */
349 print_user_string ( ix86->segs.es, ix86->regs.bx, '\0' );
350 ix86->flags &= ~CF;
351 break;
352
353 case 0x0003: /* Run command */
354 {
355 userptr_t cmd_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
356 int len = strlen_user ( cmd_u, 0 );
357 char cmd[len + 1];
358 copy_from_user ( cmd, cmd_u, 0, len + 1 );
359 DBG ( "COMBOOT: executing command '%s'\n", cmd );
360 system ( cmd );
361 DBG ( "COMBOOT: exiting after executing command...\n" );
362 rmlongjmp ( comboot_return, COMBOOT_EXIT_COMMAND );
363 }
364 break;
365
366 case 0x0004: /* Run default command */
367 /* FIXME: just exit for now */
368 rmlongjmp ( comboot_return, COMBOOT_EXIT_COMMAND );
369 break;
370
371 case 0x0005: /* Force text mode */
372 comboot_force_text_mode ( );
373 ix86->flags &= ~CF;
374 break;
375
376 case 0x0006: /* Open file */
377 {
378 int fd;
379 userptr_t file_u = real_to_user ( ix86->segs.es, ix86->regs.si );
380 int len = strlen_user ( file_u, 0 );
381 char file[len + 1];
382
383 copy_from_user ( file, file_u, 0, len + 1 );
384
385 if ( file[0] == '\0' ) {
386 DBG ( "COMBOOT: attempted open with empty file name\n" );
387 break;
388 }
389
390 DBG ( "COMBOOT: opening file '%s'\n", file );
391
392 fd = open ( file );
393
394 if ( fd < 0 ) {
395 DBG ( "COMBOOT: error opening file %s\n", file );
396 break;
397 }
398
399 /* This relies on the fact that a gPXE POSIX fd will
400 * always fit in 16 bits.
401 */
402 #if (POSIX_FD_MAX > 65535)
403 #error POSIX_FD_MAX too large
404 #endif
405 ix86->regs.si = (uint16_t) fd;
406
407 ix86->regs.cx = COMBOOT_FILE_BLOCKSZ;
408 ix86->regs.eax = fsize ( fd );
409 ix86->flags &= ~CF;
410 }
411 break;
412
413 case 0x0007: /* Read file */
414 {
415 int fd = ix86->regs.si;
416 int len = ix86->regs.cx * COMBOOT_FILE_BLOCKSZ;
417 int rc;
418 fd_set fds;
419 userptr_t buf = real_to_user ( ix86->segs.es, ix86->regs.bx );
420
421 /* Wait for data ready to read */
422 FD_ZERO ( &fds );
423 FD_SET ( fd, &fds );
424
425 select ( &fds, 1 );
426
427 rc = read_user ( fd, buf, 0, len );
428 if ( rc < 0 ) {
429 DBG ( "COMBOOT: read failed\n" );
430 ix86->regs.si = 0;
431 break;
432 }
433
434 ix86->regs.ecx = rc;
435 ix86->flags &= ~CF;
436 }
437 break;
438
439 case 0x0008: /* Close file */
440 {
441 int fd = ix86->regs.si;
442 close ( fd );
443 ix86->flags &= ~CF;
444 }
445 break;
446
447 case 0x0009: /* Call PXE Stack */
448 if ( pxe_api_call_weak ( ix86 ) != 0 )
449 ix86->flags |= CF;
450 else
451 ix86->flags &= ~CF;
452 break;
453
454 case 0x000A: /* Get Derivative-Specific Information */
455
456 /* gPXE has its own derivative ID, so there is no defined
457 * output here; just return AL for now */
458 ix86->regs.al = BZI_LOADER_TYPE_GPXE;
459 ix86->flags &= ~CF;
460 break;
461
462 case 0x000B: /* Get Serial Console Configuration */
463 #if defined(CONSOLE_SERIAL) && !defined(COMPRESERVE)
464 ix86->regs.dx = COMCONSOLE;
465 ix86->regs.cx = 115200 / COMSPEED;
466 ix86->regs.bx = 0;
467 #else
468 ix86->regs.dx = 0;
469 #endif
470
471 ix86->flags &= ~CF;
472 break;
473
474 case 0x000E: /* Get configuration file name */
475 /* FIXME: stub */
476 ix86->segs.es = rm_ds;
477 ix86->regs.bx = ( ( unsigned ) __from_data16 ( syslinux_configuration_file ) );
478 ix86->flags &= ~CF;
479 break;
480
481 case 0x000F: /* Get IPAPPEND strings */
482 /* FIXME: stub */
483 ix86->regs.cx = 0;
484 ix86->segs.es = 0;
485 ix86->regs.bx = 0;
486 ix86->flags &= ~CF;
487 break;
488
489 case 0x0010: /* Resolve hostname */
490 {
491 userptr_t hostname_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
492 int len = strlen_user ( hostname_u, 0 );
493 char hostname[len];
494 struct in_addr addr;
495
496 copy_from_user ( hostname, hostname_u, 0, len + 1 );
497
498 /* TODO:
499 * "If the hostname does not contain a dot (.), the
500 * local domain name is automatically appended."
501 */
502
503 comboot_resolv ( hostname, &addr );
504
505 ix86->regs.eax = addr.s_addr;
506 ix86->flags &= ~CF;
507 }
508 break;
509
510 case 0x0011: /* Maximum number of shuffle descriptors */
511 ix86->regs.cx = COMBOOT_MAX_SHUFFLE_DESCRIPTORS;
512 ix86->flags &= ~CF;
513 break;
514
515 case 0x0012: /* Cleanup, shuffle and boot */
516 if ( ix86->regs.cx > COMBOOT_MAX_SHUFFLE_DESCRIPTORS )
517 break;
518
519 /* Perform final cleanup */
520 shutdown ( SHUTDOWN_BOOT );
521
522 /* Perform sequence of copies */
523 shuffle ( ix86->segs.es, ix86->regs.di, ix86->regs.cx );
524
525 /* Jump to real-mode entry point */
526 __asm__ __volatile__ (
527 REAL_CODE (
528 "pushw %0\n\t"
529 "popw %%ds\n\t"
530 "pushl %1\n\t"
531 "lret\n\t"
532 )
533 :
534 : "r" ( ix86->segs.ds ),
535 "r" ( ix86->regs.ebp ),
536 "d" ( ix86->regs.ebx ),
537 "S" ( ix86->regs.esi ) );
538
539 assert ( 0 ); /* Execution should never reach this point */
540
541 break;
542
543 case 0x0013: /* Idle loop call */
544 step ( );
545 ix86->flags &= ~CF;
546 break;
547
548 case 0x0015: /* Get feature flags */
549 ix86->segs.es = rm_ds;
550 ix86->regs.bx = ( ( unsigned ) __from_data16 ( &comboot_feature_flags ) );
551 ix86->regs.cx = 1; /* Number of feature flag bytes */
552 ix86->flags &= ~CF;
553 break;
554
555 case 0x0016: /* Run kernel image */
556 {
557 userptr_t file_u = real_to_user ( ix86->segs.ds, ix86->regs.si );
558 userptr_t cmd_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
559 int file_len = strlen_user ( file_u, 0 );
560 int cmd_len = strlen_user ( cmd_u, 0 );
561 char file[file_len + 1];
562 char cmd[cmd_len + 1];
563
564 copy_from_user ( file, file_u, 0, file_len + 1 );
565 copy_from_user ( cmd, cmd_u, 0, cmd_len + 1 );
566
567 DBG ( "COMBOOT: run kernel %s %s\n", file, cmd );
568 comboot_fetch_kernel ( file, cmd );
569 /* Technically, we should return if we
570 * couldn't load the kernel, but it's not safe
571 * to do that since we have just overwritten
572 * part of the COMBOOT program's memory space.
573 */
574 DBG ( "COMBOOT: exiting to run kernel...\n" );
575 rmlongjmp ( comboot_return, COMBOOT_EXIT_RUN_KERNEL );
576 }
577 break;
578
579 case 0x0017: /* Report video mode change */
580 comboot_graphics_mode = ix86->regs.bx;
581 ix86->flags &= ~CF;
582 break;
583
584 case 0x0018: /* Query custom font */
585 /* FIXME: stub */
586 ix86->regs.al = 0;
587 ix86->segs.es = 0;
588 ix86->regs.bx = 0;
589 ix86->flags &= ~CF;
590 break;
591
592 case 0x001B: /* Cleanup, shuffle and boot to real mode */
593 if ( ix86->regs.cx > COMBOOT_MAX_SHUFFLE_DESCRIPTORS )
594 break;
595
596 /* Perform final cleanup */
597 shutdown ( SHUTDOWN_BOOT );
598
599 /* Perform sequence of copies */
600 shuffle ( ix86->segs.es, ix86->regs.di, ix86->regs.cx );
601
602 /* Copy initial register values to .text16 */
603 memcpy_user ( real_to_user ( rm_cs, (unsigned) __from_text16 ( &comboot_initial_regs ) ), 0,
604 real_to_user ( ix86->segs.ds, ix86->regs.si ), 0,
605 sizeof(syslinux_rm_regs) );
606
607 /* Load initial register values */
608 __asm__ __volatile__ (
609 REAL_CODE (
610 /* Point SS:SP at the register value structure */
611 "pushw %%cs\n\t"
612 "popw %%ss\n\t"
613 "movw $comboot_initial_regs, %%sp\n\t"
614
615 /* Segment registers */
616 "popw %%es\n\t"
617 "popw %%ax\n\t" /* Skip CS */
618 "popw %%ds\n\t"
619 "popw %%ax\n\t" /* Skip SS for now */
620 "popw %%fs\n\t"
621 "popw %%gs\n\t"
622
623 /* GP registers */
624 "popl %%eax\n\t"
625 "popl %%ecx\n\t"
626 "popl %%edx\n\t"
627 "popl %%ebx\n\t"
628 "popl %%ebp\n\t" /* Skip ESP for now */
629 "popl %%ebp\n\t"
630 "popl %%esi\n\t"
631 "popl %%edi\n\t"
632
633 /* Load correct SS:ESP */
634 "movw $(comboot_initial_regs + 6), %%sp\n\t"
635 "popw %%ss\n\t"
636 "movl %%cs:(comboot_initial_regs + 28), %%esp\n\t"
637
638 "ljmp *%%cs:(comboot_initial_regs + 44)\n\t"
639 )
640 : : );
641
642 break;
643
644 case 0x001C: /* Get pointer to auxilliary data vector */
645 /* FIXME: stub */
646 ix86->regs.cx = 0; /* Size of the ADV */
647 ix86->flags &= ~CF;
648 break;
649
650 case 0x001D: /* Write auxilliary data vector */
651 /* FIXME: stub */
652 ix86->flags &= ~CF;
653 break;
654
655 default:
656 DBG ( "COMBOOT unknown int22 function %04x\n", ix86->regs.ax );
657 break;
658 }
659 }
660
661 /**
662 * Hook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h)
663 */
hook_comboot_interrupts()664 void hook_comboot_interrupts ( ) {
665
666 __asm__ __volatile__ (
667 TEXT16_CODE ( "\nint20_wrapper:\n\t"
668 "pushl %0\n\t"
669 "pushw %%cs\n\t"
670 "call prot_call\n\t"
671 "addw $4, %%sp\n\t"
672 "iret\n\t" )
673 : : "i" ( int20 ) );
674
675 hook_bios_interrupt ( 0x20, ( unsigned int ) int20_wrapper,
676 &int20_vector );
677
678 __asm__ __volatile__ (
679 TEXT16_CODE ( "\nint21_wrapper:\n\t"
680 "pushl %0\n\t"
681 "pushw %%cs\n\t"
682 "call prot_call\n\t"
683 "addw $4, %%sp\n\t"
684 "iret\n\t" )
685 : : "i" ( int21 ) );
686
687 hook_bios_interrupt ( 0x21, ( unsigned int ) int21_wrapper,
688 &int21_vector );
689
690 __asm__ __volatile__ (
691 TEXT16_CODE ( "\nint22_wrapper:\n\t"
692 "pushl %0\n\t"
693 "pushw %%cs\n\t"
694 "call prot_call\n\t"
695 "addw $4, %%sp\n\t"
696 "iret\n\t" )
697 : : "i" ( int22) );
698
699 hook_bios_interrupt ( 0x22, ( unsigned int ) int22_wrapper,
700 &int22_vector );
701 }
702
703 /**
704 * Unhook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h)
705 */
unhook_comboot_interrupts()706 void unhook_comboot_interrupts ( ) {
707
708 unhook_bios_interrupt ( 0x20, ( unsigned int ) int20_wrapper,
709 &int20_vector );
710
711 unhook_bios_interrupt ( 0x21, ( unsigned int ) int21_wrapper,
712 &int21_vector );
713
714 unhook_bios_interrupt ( 0x22, ( unsigned int ) int22_wrapper,
715 &int22_vector );
716 }
717