xref: /freebsd/sys/i386/i386/vm86.c (revision bdd1243d)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 1997 Jonathan Lemon
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/priv.h>
35 #include <sys/proc.h>
36 #include <sys/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/mutex.h>
39 
40 #include <vm/vm.h>
41 #include <vm/pmap.h>
42 #include <vm/vm_map.h>
43 #include <vm/vm_page.h>
44 
45 #include <machine/md_var.h>
46 #include <machine/pcb.h>
47 #include <machine/pcb_ext.h>
48 #include <machine/psl.h>
49 #include <machine/specialreg.h>
50 #include <machine/sysarch.h>
51 
52 extern int vm86pa;
53 extern struct pcb *vm86pcb;
54 
55 static struct mtx vm86_lock;
56 
57 extern int vm86_bioscall(struct vm86frame *);
58 extern void vm86_biosret(struct vm86frame *);
59 
60 void vm86_prepcall(struct vm86frame *);
61 
62 struct system_map {
63 	int		type;
64 	vm_offset_t	start;
65 	vm_offset_t	end;
66 };
67 
68 #define	HLT	0xf4
69 #define	CLI	0xfa
70 #define	STI	0xfb
71 #define	PUSHF	0x9c
72 #define	POPF	0x9d
73 #define	INTn	0xcd
74 #define	IRET	0xcf
75 #define	CALLm	0xff
76 #define OPERAND_SIZE_PREFIX	0x66
77 #define ADDRESS_SIZE_PREFIX	0x67
78 #define PUSH_MASK	~(PSL_VM | PSL_RF | PSL_I)
79 #define POP_MASK	~(PSL_VIP | PSL_VIF | PSL_VM | PSL_RF | PSL_IOPL)
80 
81 static int
82 vm86_suword16(volatile void *base, int word)
83 {
84 
85 	if (curthread->td_critnest != 0) {
86 		*(volatile uint16_t *)base = word;
87 		return (0);
88 	}
89 	return (suword16(base, word));
90 }
91 
92 static int
93 vm86_suword(volatile void *base, long word)
94 {
95 
96 	if (curthread->td_critnest != 0) {
97 		*(volatile long *)base = word;
98 		return (0);
99 	}
100 	return (suword(base, word));
101 }
102 
103 static int
104 vm86_fubyte(volatile const void *base)
105 {
106 
107 	if (curthread->td_critnest != 0)
108 		return (*(volatile const u_char *)base);
109 	return (fubyte(base));
110 }
111 
112 static int
113 vm86_fuword16(volatile const void *base)
114 {
115 
116 	if (curthread->td_critnest != 0)
117 		return (*(volatile const uint16_t *)base);
118 	return (fuword16(base));
119 }
120 
121 static long
122 vm86_fuword(volatile const void *base)
123 {
124 
125 	if (curthread->td_critnest != 0)
126 		return (*(volatile const long *)base);
127 	return (fuword(base));
128 }
129 
130 static __inline caddr_t
131 MAKE_ADDR(u_short sel, u_short off)
132 {
133 	return ((caddr_t)((sel << 4) + off));
134 }
135 
136 static __inline void
137 GET_VEC(u_int vec, u_short *sel, u_short *off)
138 {
139 	*sel = vec >> 16;
140 	*off = vec & 0xffff;
141 }
142 
143 static __inline u_int
144 MAKE_VEC(u_short sel, u_short off)
145 {
146 	return ((sel << 16) | off);
147 }
148 
149 static __inline void
150 PUSH(u_short x, struct vm86frame *vmf)
151 {
152 	vmf->vmf_sp -= 2;
153 	vm86_suword16(MAKE_ADDR(vmf->vmf_ss, vmf->vmf_sp), x);
154 }
155 
156 static __inline void
157 PUSHL(u_int x, struct vm86frame *vmf)
158 {
159 	vmf->vmf_sp -= 4;
160 	vm86_suword(MAKE_ADDR(vmf->vmf_ss, vmf->vmf_sp), x);
161 }
162 
163 static __inline u_short
164 POP(struct vm86frame *vmf)
165 {
166 	u_short x = vm86_fuword16(MAKE_ADDR(vmf->vmf_ss, vmf->vmf_sp));
167 
168 	vmf->vmf_sp += 2;
169 	return (x);
170 }
171 
172 static __inline u_int
173 POPL(struct vm86frame *vmf)
174 {
175 	u_int x = vm86_fuword(MAKE_ADDR(vmf->vmf_ss, vmf->vmf_sp));
176 
177 	vmf->vmf_sp += 4;
178 	return (x);
179 }
180 
181 int
182 vm86_emulate(struct vm86frame *vmf)
183 {
184 	struct vm86_kernel *vm86;
185 	caddr_t addr;
186 	u_char i_byte;
187 	u_int temp_flags;
188 	int inc_ip = 1;
189 	int retcode = 0;
190 
191 	/*
192 	 * pcb_ext contains the address of the extension area, or zero if
193 	 * the extension is not present.  (This check should not be needed,
194 	 * as we can't enter vm86 mode until we set up an extension area)
195 	 */
196 	if (curpcb->pcb_ext == 0)
197 		return (SIGBUS);
198 	vm86 = &curpcb->pcb_ext->ext_vm86;
199 
200 	if (vmf->vmf_eflags & PSL_T)
201 		retcode = SIGTRAP;
202 
203 	addr = MAKE_ADDR(vmf->vmf_cs, vmf->vmf_ip);
204 	i_byte = vm86_fubyte(addr);
205 	if (i_byte == ADDRESS_SIZE_PREFIX) {
206 		i_byte = vm86_fubyte(++addr);
207 		inc_ip++;
208 	}
209 
210 	if (vm86->vm86_has_vme) {
211 		switch (i_byte) {
212 		case OPERAND_SIZE_PREFIX:
213 			i_byte = vm86_fubyte(++addr);
214 			inc_ip++;
215 			switch (i_byte) {
216 			case PUSHF:
217 				if (vmf->vmf_eflags & PSL_VIF)
218 					PUSHL((vmf->vmf_eflags & PUSH_MASK)
219 					    | PSL_IOPL | PSL_I, vmf);
220 				else
221 					PUSHL((vmf->vmf_eflags & PUSH_MASK)
222 					    | PSL_IOPL, vmf);
223 				vmf->vmf_ip += inc_ip;
224 				return (retcode);
225 
226 			case POPF:
227 				temp_flags = POPL(vmf) & POP_MASK;
228 				vmf->vmf_eflags = (vmf->vmf_eflags & ~POP_MASK)
229 				    | temp_flags | PSL_VM | PSL_I;
230 				vmf->vmf_ip += inc_ip;
231 				if (temp_flags & PSL_I) {
232 					vmf->vmf_eflags |= PSL_VIF;
233 					if (vmf->vmf_eflags & PSL_VIP)
234 						break;
235 				} else {
236 					vmf->vmf_eflags &= ~PSL_VIF;
237 				}
238 				return (retcode);
239 			}
240 			break;
241 
242 		/* VME faults here if VIP is set, but does not set VIF. */
243 		case STI:
244 			vmf->vmf_eflags |= PSL_VIF;
245 			vmf->vmf_ip += inc_ip;
246 			if ((vmf->vmf_eflags & PSL_VIP) == 0) {
247 				uprintf("fatal sti\n");
248 				return (SIGKILL);
249 			}
250 			break;
251 
252 		/* VME if no redirection support */
253 		case INTn:
254 			break;
255 
256 		/* VME if trying to set PSL_T, or PSL_I when VIP is set */
257 		case POPF:
258 			temp_flags = POP(vmf) & POP_MASK;
259 			vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
260 			    | temp_flags | PSL_VM | PSL_I;
261 			vmf->vmf_ip += inc_ip;
262 			if (temp_flags & PSL_I) {
263 				vmf->vmf_eflags |= PSL_VIF;
264 				if (vmf->vmf_eflags & PSL_VIP)
265 					break;
266 			} else {
267 				vmf->vmf_eflags &= ~PSL_VIF;
268 			}
269 			return (retcode);
270 
271 		/* VME if trying to set PSL_T, or PSL_I when VIP is set */
272 		case IRET:
273 			vmf->vmf_ip = POP(vmf);
274 			vmf->vmf_cs = POP(vmf);
275 			temp_flags = POP(vmf) & POP_MASK;
276 			vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
277 			    | temp_flags | PSL_VM | PSL_I;
278 			if (temp_flags & PSL_I) {
279 				vmf->vmf_eflags |= PSL_VIF;
280 				if (vmf->vmf_eflags & PSL_VIP)
281 					break;
282 			} else {
283 				vmf->vmf_eflags &= ~PSL_VIF;
284 			}
285 			return (retcode);
286 		}
287 		return (SIGBUS);
288 	}
289 
290 	switch (i_byte) {
291 	case OPERAND_SIZE_PREFIX:
292 		i_byte = vm86_fubyte(++addr);
293 		inc_ip++;
294 		switch (i_byte) {
295 		case PUSHF:
296 			if (vm86->vm86_eflags & PSL_VIF)
297 				PUSHL((vmf->vmf_flags & PUSH_MASK)
298 				    | PSL_IOPL | PSL_I, vmf);
299 			else
300 				PUSHL((vmf->vmf_flags & PUSH_MASK)
301 				    | PSL_IOPL, vmf);
302 			vmf->vmf_ip += inc_ip;
303 			return (retcode);
304 
305 		case POPF:
306 			temp_flags = POPL(vmf) & POP_MASK;
307 			vmf->vmf_eflags = (vmf->vmf_eflags & ~POP_MASK)
308 			    | temp_flags | PSL_VM | PSL_I;
309 			vmf->vmf_ip += inc_ip;
310 			if (temp_flags & PSL_I) {
311 				vm86->vm86_eflags |= PSL_VIF;
312 				if (vm86->vm86_eflags & PSL_VIP)
313 					break;
314 			} else {
315 				vm86->vm86_eflags &= ~PSL_VIF;
316 			}
317 			return (retcode);
318 		}
319 		return (SIGBUS);
320 
321 	case CLI:
322 		vm86->vm86_eflags &= ~PSL_VIF;
323 		vmf->vmf_ip += inc_ip;
324 		return (retcode);
325 
326 	case STI:
327 		/* if there is a pending interrupt, go to the emulator */
328 		vm86->vm86_eflags |= PSL_VIF;
329 		vmf->vmf_ip += inc_ip;
330 		if (vm86->vm86_eflags & PSL_VIP)
331 			break;
332 		return (retcode);
333 
334 	case PUSHF:
335 		if (vm86->vm86_eflags & PSL_VIF)
336 			PUSH((vmf->vmf_flags & PUSH_MASK)
337 			    | PSL_IOPL | PSL_I, vmf);
338 		else
339 			PUSH((vmf->vmf_flags & PUSH_MASK) | PSL_IOPL, vmf);
340 		vmf->vmf_ip += inc_ip;
341 		return (retcode);
342 
343 	case INTn:
344 		i_byte = vm86_fubyte(addr + 1);
345 		if ((vm86->vm86_intmap[i_byte >> 3] & (1 << (i_byte & 7))) != 0)
346 			break;
347 		if (vm86->vm86_eflags & PSL_VIF)
348 			PUSH((vmf->vmf_flags & PUSH_MASK)
349 			    | PSL_IOPL | PSL_I, vmf);
350 		else
351 			PUSH((vmf->vmf_flags & PUSH_MASK) | PSL_IOPL, vmf);
352 		PUSH(vmf->vmf_cs, vmf);
353 		PUSH(vmf->vmf_ip + inc_ip + 1, vmf);	/* increment IP */
354 		GET_VEC(vm86_fuword((caddr_t)(i_byte * 4)),
355 		     &vmf->vmf_cs, &vmf->vmf_ip);
356 		vmf->vmf_flags &= ~PSL_T;
357 		vm86->vm86_eflags &= ~PSL_VIF;
358 		return (retcode);
359 
360 	case IRET:
361 		vmf->vmf_ip = POP(vmf);
362 		vmf->vmf_cs = POP(vmf);
363 		temp_flags = POP(vmf) & POP_MASK;
364 		vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
365 		    | temp_flags | PSL_VM | PSL_I;
366 		if (temp_flags & PSL_I) {
367 			vm86->vm86_eflags |= PSL_VIF;
368 			if (vm86->vm86_eflags & PSL_VIP)
369 				break;
370 		} else {
371 			vm86->vm86_eflags &= ~PSL_VIF;
372 		}
373 		return (retcode);
374 
375 	case POPF:
376 		temp_flags = POP(vmf) & POP_MASK;
377 		vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
378 		    | temp_flags | PSL_VM | PSL_I;
379 		vmf->vmf_ip += inc_ip;
380 		if (temp_flags & PSL_I) {
381 			vm86->vm86_eflags |= PSL_VIF;
382 			if (vm86->vm86_eflags & PSL_VIP)
383 				break;
384 		} else {
385 			vm86->vm86_eflags &= ~PSL_VIF;
386 		}
387 		return (retcode);
388 	}
389 	return (SIGBUS);
390 }
391 
392 #define PGTABLE_SIZE	((1024 + 64) * 1024 / PAGE_SIZE)
393 #define INTMAP_SIZE	32
394 #define IOMAP_SIZE	ctob(IOPAGES)
395 #define TSS_SIZE \
396 	(sizeof(struct pcb_ext) - sizeof(struct segment_descriptor) + \
397 	 INTMAP_SIZE + IOMAP_SIZE + 1)
398 
399 struct vm86_layout_pae {
400 	uint64_t	vml_pgtbl[PGTABLE_SIZE];
401 	struct 	pcb vml_pcb;
402 	struct	pcb_ext vml_ext;
403 	char	vml_intmap[INTMAP_SIZE];
404 	char	vml_iomap[IOMAP_SIZE];
405 	char	vml_iomap_trailer;
406 };
407 
408 struct vm86_layout_nopae {
409 	uint32_t	vml_pgtbl[PGTABLE_SIZE];
410 	struct 	pcb vml_pcb;
411 	struct	pcb_ext vml_ext;
412 	char	vml_intmap[INTMAP_SIZE];
413 	char	vml_iomap[IOMAP_SIZE];
414 	char	vml_iomap_trailer;
415 };
416 
417 _Static_assert(sizeof(struct vm86_layout_pae) <= ctob(3),
418     "struct vm86_layout_pae exceeds space allocated in locore.s");
419 _Static_assert(sizeof(struct vm86_layout_nopae) <= ctob(3),
420     "struct vm86_layout_nopae exceeds space allocated in locore.s");
421 
422 static void
423 vm86_initialize_pae(void)
424 {
425 	int i;
426 	u_int *addr;
427 	struct vm86_layout_pae *vml;
428 	struct pcb *pcb;
429 	struct pcb_ext *ext;
430 	struct soft_segment_descriptor ssd = {
431 		0,			/* segment base address (overwritten) */
432 		0,			/* length (overwritten) */
433 		SDT_SYS386TSS,		/* segment type */
434 		0,			/* priority level */
435 		1,			/* descriptor present */
436 		0, 0,
437 		0,			/* default 16 size */
438 		0			/* granularity */
439 	};
440 
441 	/*
442 	 * Below is the memory layout that we use for the vm86 region.
443 	 *
444 	 * +--------+
445 	 * |        |
446 	 * |        |
447 	 * | page 0 |
448 	 * |        | +--------+
449 	 * |        | | stack  |
450 	 * +--------+ +--------+ <--------- vm86paddr
451 	 * |        | |Page Tbl| 1M + 64K = 272 entries = 1088 bytes
452 	 * |        | +--------+
453 	 * |        | |  PCB   | size: ~240 bytes
454 	 * | page 1 | |PCB Ext | size: ~140 bytes (includes TSS)
455 	 * |        | +--------+
456 	 * |        | |int map |
457 	 * |        | +--------+
458 	 * +--------+ |        |
459 	 * | page 2 | |  I/O   |
460 	 * +--------+ | bitmap |
461 	 * | page 3 | |        |
462 	 * |        | +--------+
463 	 * +--------+
464 	 */
465 
466 	/*
467 	 * A rudimentary PCB must be installed, in order to get to the
468 	 * PCB extension area.  We use the PCB area as a scratchpad for
469 	 * data storage, the layout of which is shown below.
470 	 *
471 	 * pcb_esi	= new PTD entry 0
472 	 * pcb_ebp	= pointer to frame on vm86 stack
473 	 * pcb_esp	=    stack frame pointer at time of switch
474 	 * pcb_ebx	= va of vm86 page table
475 	 * pcb_eip	=    argument pointer to initial call
476 	 * pcb_vm86[0]	=    saved TSS descriptor, word 0
477 	 * pcb_vm86[1]	=    saved TSS descriptor, word 1
478 	 */
479 #define new_ptd		pcb_esi
480 #define vm86_frame	pcb_ebp
481 #define pgtable_va	pcb_ebx
482 
483 	vml = (struct vm86_layout_pae *)vm86paddr;
484 	pcb = &vml->vml_pcb;
485 	ext = &vml->vml_ext;
486 
487 	mtx_init(&vm86_lock, "vm86 lock", NULL, MTX_DEF);
488 
489 	bzero(pcb, sizeof(struct pcb));
490 	pcb->new_ptd = vm86pa | PG_V | PG_RW | PG_U;
491 	pcb->vm86_frame = vm86paddr - sizeof(struct vm86frame);
492 	pcb->pgtable_va = vm86paddr;
493 	pcb->pcb_flags = PCB_VM86CALL;
494 	pcb->pcb_ext = ext;
495 
496 	bzero(ext, sizeof(struct pcb_ext));
497 	ext->ext_tss.tss_esp0 = vm86paddr;
498 	ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
499 	ext->ext_tss.tss_ioopt =
500 		((u_int)vml->vml_iomap - (u_int)&ext->ext_tss) << 16;
501 	ext->ext_iomap = vml->vml_iomap;
502 	ext->ext_vm86.vm86_intmap = vml->vml_intmap;
503 
504 	if (cpu_feature & CPUID_VME)
505 		ext->ext_vm86.vm86_has_vme = (rcr4() & CR4_VME ? 1 : 0);
506 
507 	addr = (u_int *)ext->ext_vm86.vm86_intmap;
508 	for (i = 0; i < (INTMAP_SIZE + IOMAP_SIZE) / sizeof(u_int); i++)
509 		*addr++ = 0;
510 	vml->vml_iomap_trailer = 0xff;
511 
512 	ssd.ssd_base = (u_int)&ext->ext_tss;
513 	ssd.ssd_limit = TSS_SIZE - 1;
514 	ssdtosd(&ssd, &ext->ext_tssd);
515 
516 	vm86pcb = pcb;
517 
518 #if 0
519         /*
520          * use whatever is leftover of the vm86 page layout as a
521          * message buffer so we can capture early output.
522          */
523         msgbufinit((vm_offset_t)vm86paddr + sizeof(struct vm86_layout),
524             ctob(3) - sizeof(struct vm86_layout));
525 #endif
526 }
527 
528 static void
529 vm86_initialize_nopae(void)
530 {
531 	int i;
532 	u_int *addr;
533 	struct vm86_layout_nopae *vml;
534 	struct pcb *pcb;
535 	struct pcb_ext *ext;
536 	struct soft_segment_descriptor ssd = {
537 		0,			/* segment base address (overwritten) */
538 		0,			/* length (overwritten) */
539 		SDT_SYS386TSS,		/* segment type */
540 		0,			/* priority level */
541 		1,			/* descriptor present */
542 		0, 0,
543 		0,			/* default 16 size */
544 		0			/* granularity */
545 	};
546 
547 	vml = (struct vm86_layout_nopae *)vm86paddr;
548 	pcb = &vml->vml_pcb;
549 	ext = &vml->vml_ext;
550 
551 	mtx_init(&vm86_lock, "vm86 lock", NULL, MTX_DEF);
552 
553 	bzero(pcb, sizeof(struct pcb));
554 	pcb->new_ptd = vm86pa | PG_V | PG_RW | PG_U;
555 	pcb->vm86_frame = vm86paddr - sizeof(struct vm86frame);
556 	pcb->pgtable_va = vm86paddr;
557 	pcb->pcb_flags = PCB_VM86CALL;
558 	pcb->pcb_ext = ext;
559 
560 	bzero(ext, sizeof(struct pcb_ext));
561 	ext->ext_tss.tss_esp0 = vm86paddr;
562 	ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
563 	ext->ext_tss.tss_ioopt =
564 		((u_int)vml->vml_iomap - (u_int)&ext->ext_tss) << 16;
565 	ext->ext_iomap = vml->vml_iomap;
566 	ext->ext_vm86.vm86_intmap = vml->vml_intmap;
567 
568 	if (cpu_feature & CPUID_VME)
569 		ext->ext_vm86.vm86_has_vme = (rcr4() & CR4_VME ? 1 : 0);
570 
571 	addr = (u_int *)ext->ext_vm86.vm86_intmap;
572 	for (i = 0; i < (INTMAP_SIZE + IOMAP_SIZE) / sizeof(u_int); i++)
573 		*addr++ = 0;
574 	vml->vml_iomap_trailer = 0xff;
575 
576 	ssd.ssd_base = (u_int)&ext->ext_tss;
577 	ssd.ssd_limit = TSS_SIZE - 1;
578 	ssdtosd(&ssd, &ext->ext_tssd);
579 
580 	vm86pcb = pcb;
581 
582 #if 0
583         /*
584          * use whatever is leftover of the vm86 page layout as a
585          * message buffer so we can capture early output.
586          */
587         msgbufinit((vm_offset_t)vm86paddr + sizeof(struct vm86_layout),
588             ctob(3) - sizeof(struct vm86_layout));
589 #endif
590 }
591 
592 void
593 vm86_initialize(void)
594 {
595 
596 	if (pae_mode)
597 		vm86_initialize_pae();
598 	else
599 		vm86_initialize_nopae();
600 }
601 
602 vm_offset_t
603 vm86_getpage(struct vm86context *vmc, int pagenum)
604 {
605 	int i;
606 
607 	for (i = 0; i < vmc->npages; i++)
608 		if (vmc->pmap[i].pte_num == pagenum)
609 			return (vmc->pmap[i].kva);
610 	return (0);
611 }
612 
613 vm_offset_t
614 vm86_addpage(struct vm86context *vmc, int pagenum, vm_offset_t kva)
615 {
616 	int i, flags = 0;
617 
618 	for (i = 0; i < vmc->npages; i++)
619 		if (vmc->pmap[i].pte_num == pagenum)
620 			goto overlap;
621 
622 	if (vmc->npages == VM86_PMAPSIZE)
623 		goto full;			/* XXX grow map? */
624 
625 	if (kva == 0) {
626 		kva = (vm_offset_t)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
627 		flags = VMAP_MALLOC;
628 	}
629 
630 	i = vmc->npages++;
631 	vmc->pmap[i].flags = flags;
632 	vmc->pmap[i].kva = kva;
633 	vmc->pmap[i].pte_num = pagenum;
634 	return (kva);
635 overlap:
636 	panic("vm86_addpage: overlap");
637 full:
638 	panic("vm86_addpage: not enough room");
639 }
640 
641 /*
642  * called from vm86_bioscall, while in vm86 address space, to finalize setup.
643  */
644 void
645 vm86_prepcall(struct vm86frame *vmf)
646 {
647 	struct vm86_kernel *vm86;
648 	uint32_t *stack;
649 	uint8_t *code;
650 
651 	code = (void *)0xa00;
652 	stack = (void *)(0x1000 - 2);	/* keep aligned */
653 	if ((vmf->vmf_trapno & PAGE_MASK) <= 0xff) {
654 		/* interrupt call requested */
655 		code[0] = INTn;
656 		code[1] = vmf->vmf_trapno & 0xff;
657 		code[2] = HLT;
658 		vmf->vmf_ip = (uintptr_t)code;
659 		vmf->vmf_cs = 0;
660 	} else {
661 		code[0] = HLT;
662 		stack--;
663 		stack[0] = MAKE_VEC(0, (uintptr_t)code);
664 	}
665 	vmf->vmf_sp = (uintptr_t)stack;
666 	vmf->vmf_ss = 0;
667 	vmf->kernel_fs = vmf->kernel_es = vmf->kernel_ds = 0;
668 	vmf->vmf_eflags = PSL_VIF | PSL_VM | PSL_USER;
669 
670 	vm86 = &curpcb->pcb_ext->ext_vm86;
671 	if (!vm86->vm86_has_vme)
672 		vm86->vm86_eflags = vmf->vmf_eflags;  /* save VIF, VIP */
673 }
674 
675 /*
676  * vm86 trap handler; determines whether routine succeeded or not.
677  * Called while in vm86 space, returns to calling process.
678  */
679 void
680 vm86_trap(struct vm86frame *vmf)
681 {
682 	void (*p)(struct vm86frame *);
683 	caddr_t addr;
684 
685 	/* "should not happen" */
686 	if ((vmf->vmf_eflags & PSL_VM) == 0)
687 		panic("vm86_trap called, but not in vm86 mode");
688 
689 	addr = MAKE_ADDR(vmf->vmf_cs, vmf->vmf_ip);
690 	if (*(u_char *)addr == HLT)
691 		vmf->vmf_trapno = vmf->vmf_eflags & PSL_C;
692 	else
693 		vmf->vmf_trapno = vmf->vmf_trapno << 16;
694 
695 	p = (void (*)(struct vm86frame *))((uintptr_t)vm86_biosret +
696 	    setidt_disp);
697 	p(vmf);
698 }
699 
700 int
701 vm86_intcall(int intnum, struct vm86frame *vmf)
702 {
703 	int (*p)(struct vm86frame *);
704 	int retval;
705 
706 	if (intnum < 0 || intnum > 0xff)
707 		return (EINVAL);
708 
709 	vmf->vmf_trapno = intnum;
710 	p = (int (*)(struct vm86frame *))((uintptr_t)vm86_bioscall +
711 	    setidt_disp);
712 	mtx_lock(&vm86_lock);
713 	critical_enter();
714 	retval = p(vmf);
715 	critical_exit();
716 	mtx_unlock(&vm86_lock);
717 	return (retval);
718 }
719 
720 /*
721  * struct vm86context contains the page table to use when making
722  * vm86 calls.  If intnum is a valid interrupt number (0-255), then
723  * the "interrupt trampoline" will be used, otherwise we use the
724  * caller's cs:ip routine.
725  */
726 int
727 vm86_datacall(int intnum, struct vm86frame *vmf, struct vm86context *vmc)
728 {
729 	uint64_t *pte_pae;
730 	uint32_t *pte_nopae;
731 	int (*p)(struct vm86frame *);
732 	vm_paddr_t page;
733 	int i, entry, retval;
734 
735 	mtx_lock(&vm86_lock);
736 	if (pae_mode) {
737 		pte_pae = (uint64_t *)vm86paddr;
738 		for (i = 0; i < vmc->npages; i++) {
739 			page = vtophys(vmc->pmap[i].kva & PG_FRAME_PAE);
740 			entry = vmc->pmap[i].pte_num;
741 			vmc->pmap[i].old_pte = pte_pae[entry];
742 			pte_pae[entry] = page | PG_V | PG_RW | PG_U;
743 			pmap_invalidate_page(kernel_pmap, vmc->pmap[i].kva);
744 		}
745 	} else {
746 		pte_nopae = (uint32_t *)vm86paddr;
747 		for (i = 0; i < vmc->npages; i++) {
748 			page = vtophys(vmc->pmap[i].kva & PG_FRAME_NOPAE);
749 			entry = vmc->pmap[i].pte_num;
750 			vmc->pmap[i].old_pte = pte_nopae[entry];
751 			pte_nopae[entry] = page | PG_V | PG_RW | PG_U;
752 			pmap_invalidate_page(kernel_pmap, vmc->pmap[i].kva);
753 		}
754 	}
755 
756 	vmf->vmf_trapno = intnum;
757 	p = (int (*)(struct vm86frame *))((uintptr_t)vm86_bioscall +
758 	    setidt_disp);
759 	critical_enter();
760 	retval = p(vmf);
761 	critical_exit();
762 
763 	if (pae_mode) {
764 		for (i = 0; i < vmc->npages; i++) {
765 			entry = vmc->pmap[i].pte_num;
766 			pte_pae[entry] = vmc->pmap[i].old_pte;
767 			pmap_invalidate_page(kernel_pmap, vmc->pmap[i].kva);
768 		}
769 	} else {
770 		for (i = 0; i < vmc->npages; i++) {
771 			entry = vmc->pmap[i].pte_num;
772 			pte_nopae[entry] = vmc->pmap[i].old_pte;
773 			pmap_invalidate_page(kernel_pmap, vmc->pmap[i].kva);
774 		}
775 	}
776 	mtx_unlock(&vm86_lock);
777 
778 	return (retval);
779 }
780 
781 vm_offset_t
782 vm86_getaddr(struct vm86context *vmc, u_short sel, u_short off)
783 {
784 	int i, page;
785 	vm_offset_t addr;
786 
787 	addr = (vm_offset_t)MAKE_ADDR(sel, off);
788 	page = addr >> PAGE_SHIFT;
789 	for (i = 0; i < vmc->npages; i++)
790 		if (page == vmc->pmap[i].pte_num)
791 			return (vmc->pmap[i].kva + (addr & PAGE_MASK));
792 	return (0);
793 }
794 
795 int
796 vm86_getptr(struct vm86context *vmc, vm_offset_t kva, u_short *sel,
797      u_short *off)
798 {
799 	int i;
800 
801 	for (i = 0; i < vmc->npages; i++)
802 		if (kva >= vmc->pmap[i].kva &&
803 		    kva < vmc->pmap[i].kva + PAGE_SIZE) {
804 			*off = kva - vmc->pmap[i].kva;
805 			*sel = vmc->pmap[i].pte_num << 8;
806 			return (1);
807 		}
808 	return (0);
809 }
810 
811 int
812 vm86_sysarch(struct thread *td, char *args)
813 {
814 	int error = 0;
815 	struct i386_vm86_args ua;
816 	struct vm86_kernel *vm86;
817 
818 	if ((error = copyin(args, &ua, sizeof(struct i386_vm86_args))) != 0)
819 		return (error);
820 
821 	if (td->td_pcb->pcb_ext == 0)
822 		if ((error = i386_extend_pcb(td)) != 0)
823 			return (error);
824 	vm86 = &td->td_pcb->pcb_ext->ext_vm86;
825 
826 	switch (ua.sub_op) {
827 	case VM86_INIT: {
828 		struct vm86_init_args sa;
829 
830 		if ((error = copyin(ua.sub_args, &sa, sizeof(sa))) != 0)
831 			return (error);
832 		if (cpu_feature & CPUID_VME)
833 			vm86->vm86_has_vme = (rcr4() & CR4_VME ? 1 : 0);
834 		else
835 			vm86->vm86_has_vme = 0;
836 		vm86->vm86_inited = 1;
837 		vm86->vm86_debug = sa.debug;
838 		bcopy(&sa.int_map, vm86->vm86_intmap, 32);
839 		}
840 		break;
841 
842 #if 0
843 	case VM86_SET_VME: {
844 		struct vm86_vme_args sa;
845 
846 		if ((cpu_feature & CPUID_VME) == 0)
847 			return (ENODEV);
848 
849 		if (error = copyin(ua.sub_args, &sa, sizeof(sa)))
850 			return (error);
851 		if (sa.state)
852 			load_cr4(rcr4() | CR4_VME);
853 		else
854 			load_cr4(rcr4() & ~CR4_VME);
855 		}
856 		break;
857 #endif
858 
859 	case VM86_GET_VME: {
860 		struct vm86_vme_args sa;
861 
862 		sa.state = (rcr4() & CR4_VME ? 1 : 0);
863         	error = copyout(&sa, ua.sub_args, sizeof(sa));
864 		}
865 		break;
866 
867 	case VM86_INTCALL: {
868 		struct vm86_intcall_args sa;
869 
870 		if ((error = priv_check(td, PRIV_VM86_INTCALL)))
871 			return (error);
872 		if ((error = copyin(ua.sub_args, &sa, sizeof(sa))))
873 			return (error);
874 		if ((error = vm86_intcall(sa.intnum, &sa.vmf)))
875 			return (error);
876 		error = copyout(&sa, ua.sub_args, sizeof(sa));
877 		}
878 		break;
879 
880 	default:
881 		error = EINVAL;
882 	}
883 	return (error);
884 }
885