summaryrefslogtreecommitdiffstats
path: root/Documentation/lguest/lguest.c
blob: 62a8133393e19d3991781317bc10c834a6ed5939 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
/* Simple program to layout "physical" memory for new lguest guest.
 * Linked high to avoid likely physical memory.  */
#define _LARGEFILE64_SOURCE
#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <err.h>
#include <stdint.h>
#include <stdlib.h>
#include <elf.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <stdbool.h>
#include <errno.h>
#include <ctype.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <time.h>
#include <netinet/in.h>
#include <net/if.h>
#include <linux/sockios.h>
#include <linux/if_tun.h>
#include <sys/uio.h>
#include <termios.h>
#include <getopt.h>
#include <zlib.h>
typedef unsigned long long u64;
typedef uint32_t u32;
typedef uint16_t u16;
typedef uint8_t u8;
#include "../../include/linux/lguest_launcher.h"
#include "../../include/asm-i386/e820.h"

#define PAGE_PRESENT 0x7 	/* Present, RW, Execute */
#define NET_PEERNUM 1
#define BRIDGE_PFX "bridge:"
#ifndef SIOCBRADDIF
#define SIOCBRADDIF	0x89a2		/* add interface to bridge      */
#endif

static bool verbose;
#define verbose(args...) \
	do { if (verbose) printf(args); } while(0)
static int waker_fd;
static u32 top;

struct device_list
{
	fd_set infds;
	int max_infd;

	struct lguest_device_desc *descs;
	struct device *dev;
	struct device **lastdev;
};

struct device
{
	struct device *next;
	struct lguest_device_desc *desc;
	void *mem;

	/* Watch this fd if handle_input non-NULL. */
	int fd;
	bool (*handle_input)(int fd, struct device *me);

	/* Watch DMA to this key if handle_input non-NULL. */
	unsigned long watch_key;
	u32 (*handle_output)(int fd, const struct iovec *iov,
			     unsigned int num, struct device *me);

	/* Device-specific data. */
	void *priv;
};

static int open_or_die(const char *name, int flags)
{
	int fd = open(name, flags);
	if (fd < 0)
		err(1, "Failed to open %s", name);
	return fd;
}

static void *map_zeroed_pages(unsigned long addr, unsigned int num)
{
	static int fd = -1;

	if (fd == -1)
		fd = open_or_die("/dev/zero", O_RDONLY);

	if (mmap((void *)addr, getpagesize() * num,
		 PROT_READ|PROT_WRITE|PROT_EXEC, MAP_FIXED|MAP_PRIVATE, fd, 0)
	    != (void *)addr)
		err(1, "Mmaping %u pages of /dev/zero @%p", num, (void *)addr);
	return (void *)addr;
}

/* Find magic string marking entry point, return entry point. */
static unsigned long entry_point(void *start, void *end,
				 unsigned long page_offset)
{
	void *p;

	for (p = start; p < end; p++)
		if (memcmp(p, "GenuineLguest", strlen("GenuineLguest")) == 0)
			return (long)p + strlen("GenuineLguest") + page_offset;

	err(1, "Is this image a genuine lguest?");
}

/* Returns the entry point */
static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr,
			     unsigned long *page_offset)
{
	void *addr;
	Elf32_Phdr phdr[ehdr->e_phnum];
	unsigned int i;
	unsigned long start = -1UL, end = 0;

	/* Sanity checks. */
	if (ehdr->e_type != ET_EXEC
	    || ehdr->e_machine != EM_386
	    || ehdr->e_phentsize != sizeof(Elf32_Phdr)
	    || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr))
		errx(1, "Malformed elf header");

	if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0)
		err(1, "Seeking to program headers");
	if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr))
		err(1, "Reading program headers");

	*page_offset = 0;
	/* We map the loadable segments at virtual addresses corresponding
	 * to their physical addresses (our virtual == guest physical). */
	for (i = 0; i < ehdr->e_phnum; i++) {
		if (phdr[i].p_type != PT_LOAD)
			continue;

		verbose("Section %i: size %i addr %p\n",
			i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);

		/* We expect linear address space. */
		if (!*page_offset)
			*page_offset = phdr[i].p_vaddr - phdr[i].p_paddr;
		else if (*page_offset != phdr[i].p_vaddr - phdr[i].p_paddr)
			errx(1, "Page offset of section %i different", i);

		if (phdr[i].p_paddr < start)
			start = phdr[i].p_paddr;
		if (phdr[i].p_paddr + phdr[i].p_filesz > end)
			end = phdr[i].p_paddr + phdr[i].p_filesz;

		/* We map everything private, writable. */
		addr = mmap((void *)phdr[i].p_paddr,
			    phdr[i].p_filesz,
			    PROT_READ|PROT_WRITE|PROT_EXEC,
			    MAP_FIXED|MAP_PRIVATE,
			    elf_fd, phdr[i].p_offset);
		if (addr != (void *)phdr[i].p_paddr)
			err(1, "Mmaping vmlinux seg %i gave %p not %p",
			    i, addr, (void *)phdr[i].p_paddr);
	}

	return entry_point((void *)start, (void *)end, *page_offset);
}

/* This is amazingly reliable. */
static unsigned long intuit_page_offset(unsigned char *img, unsigned long len)
{
	unsigned int i, possibilities[256] = { 0 };

	for (i = 0; i + 4 < len; i++) {
		/* mov 0xXXXXXXXX,%eax */
		if (img[i] == 0xA1 && ++possibilities[img[i+4]] > 3)
			return (unsigned long)img[i+4] << 24;
	}
	errx(1, "could not determine page offset");
}

static unsigned long unpack_bzimage(int fd, unsigned long *page_offset)
{
	gzFile f;
	int ret, len = 0;
	void *img = (void *)0x100000;

	f = gzdopen(fd, "rb");
	while ((ret = gzread(f, img + len, 65536)) > 0)
		len += ret;
	if (ret < 0)
		err(1, "reading image from bzImage");

	verbose("Unpacked size %i addr %p\n", len, img);
	*page_offset = intuit_page_offset(img, len);

	return entry_point(img, img + len, *page_offset);
}

static unsigned long load_bzimage(int fd, unsigned long *page_offset)
{
	unsigned char c;
	int state = 0;

	/* Ugly brute force search for gzip header. */
	while (read(fd, &c, 1) == 1) {
		switch (state) {
		case 0:
			if (c == 0x1F)
				state++;
			break;
		case 1:
			if (c == 0x8B)
				state++;
			else
				state = 0;
			break;
		case 2 ... 8:
			state++;
			break;
		case 9:
			lseek(fd, -10, SEEK_CUR);
			if (c != 0x03) /* Compressed under UNIX. */
				state = -1;
			else
				return unpack_bzimage(fd, page_offset);
		}
	}
	errx(1, "Could not find kernel in bzImage");
}

static unsigned long load_kernel(int fd, unsigned long *page_offset)
{
	Elf32_Ehdr hdr;

	if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr))
		err(1, "Reading kernel");

	if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0)
		return map_elf(fd, &hdr, page_offset);

	return load_bzimage(fd, page_offset);
}

static inline unsigned long page_align(unsigned long addr)
{
	return ((addr + getpagesize()-1) & ~(getpagesize()-1));
}

/* initrd gets loaded at top of memory: return length. */
static unsigned long load_initrd(const char *name, unsigned long mem)
{
	int ifd;
	struct stat st;
	unsigned long len;
	void *iaddr;

	ifd = open_or_die(name, O_RDONLY);
	if (fstat(ifd, &st) < 0)
		err(1, "fstat() on initrd '%s'", name);

	len = page_align(st.st_size);
	iaddr = mmap((void *)mem - len, st.st_size,
		     PROT_READ|PROT_EXEC|PROT_WRITE,
		     MAP_FIXED|MAP_PRIVATE, ifd, 0);
	if (iaddr != (void *)mem - len)
		err(1, "Mmaping initrd '%s' returned %p not %p",
		    name, iaddr, (void *)mem - len);
	close(ifd);
	verbose("mapped initrd %s size=%lu @ %p\n", name, st.st_size, iaddr);
	return len;
}

static unsigned long setup_pagetables(unsigned long mem,
				      unsigned long initrd_size,
				      unsigned long page_offset)
{
	u32 *pgdir, *linear;
	unsigned int mapped_pages, i, linear_pages;
	unsigned int ptes_per_page = getpagesize()/sizeof(u32);

	/* If we can map all of memory above page_offset, we do so. */
	if (mem <= -page_offset)
		mapped_pages = mem/getpagesize();
	else
		mapped_pages = -page_offset/getpagesize();

	/* Each linear PTE page can map ptes_per_page pages. */
	linear_pages = (mapped_pages + ptes_per_page-1)/ptes_per_page;

	/* We lay out top-level then linear mapping immediately below initrd */
	pgdir = (void *)mem - initrd_size - getpagesize();
	linear = (void *)pgdir - linear_pages*getpagesize();

	for (i = 0; i < mapped_pages; i++)
		linear[i] = ((i * getpagesize()) | PAGE_PRESENT);

	/* Now set up pgd so that this memory is at page_offset */
	for (i = 0; i < mapped_pages; i += ptes_per_page) {
		pgdir[(i + page_offset/getpagesize())/ptes_per_page]
			= (((u32)linear + i*sizeof(u32)) | PAGE_PRESENT);
	}

	verbose("Linear mapping of %u pages in %u pte pages at %p\n",
		mapped_pages, linear_pages, linear);

	return (unsigned long)pgdir;
}

static void concat(char *dst, char *args[])
{
	unsigned int i, len = 0;

	for (i = 0; args[i]; i++) {
		strcpy(dst+len, args[i]);
		strcat(dst+len, " ");
		len += strlen(args[i]) + 1;
	}
	/* In case it's empty. */
	dst[len] = '\0';
}

static int tell_kernel(u32 pgdir, u32 start, u32 page_offset)
{
	u32 args[] = { LHREQ_INITIALIZE,
		       top/getpagesize(), pgdir, start, page_offset };
	int fd;

	fd = open_or_die("/dev/lguest", O_RDWR);
	if (write(fd, args, sizeof(args)) < 0)
		err(1, "Writing to /dev/lguest");
	return fd;
}

static void set_fd(int fd, struct device_list *devices)
{
	FD_SET(fd, &devices->infds);
	if (fd > devices->max_infd)
		devices->max_infd = fd;
}

/* When input arrives, we tell the kernel to kick lguest out with -EAGAIN. */
static void wake_parent(int pipefd, int lguest_fd, struct device_list *devices)
{
	set_fd(pipefd, devices);

	for (;;) {
		fd_set rfds = devices->infds;
		u32 args[] = { LHREQ_BREAK, 1 };

		select(devices->max_infd+1, &rfds, NULL, NULL, NULL);
		if (FD_ISSET(pipefd, &rfds)) {
			int ignorefd;
			if (read(pipefd, &ignorefd, sizeof(ignorefd)) == 0)
				exit(0);
			FD_CLR(ignorefd, &devices->infds);
		} else
			write(lguest_fd, args, sizeof(args));
	}
}

static int setup_waker(int lguest_fd, struct device_list *device_list)
{
	int pipefd[2], child;

	pipe(pipefd);
	child = fork();
	if (child == -1)
		err(1, "forking");

	if (child == 0) {
		close(pipefd[1]);
		wake_parent(pipefd[0], lguest_fd, device_list);
	}
	close(pipefd[0]);

	return pipefd[1];
}

static void *_check_pointer(unsigned long addr, unsigned int size,
			    unsigned int line)
{
	if (addr >= top || addr + size >= top)
		errx(1, "%s:%i: Invalid address %li", __FILE__, line, addr);
	return (void *)addr;
}
#define check_pointer(addr,size) _check_pointer(addr, size, __LINE__)

/* Returns pointer to dma->used_len */
static u32 *dma2iov(unsigned long dma, struct iovec iov[], unsigned *num)
{
	unsigned int i;
	struct lguest_dma *udma;

	udma = check_pointer(dma, sizeof(*udma));
	for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
		if (!udma->len[i])
			break;

		iov[i].iov_base = check_pointer(udma->addr[i], udma->len[i]);
		iov[i].iov_len = udma->len[i];
	}
	*num = i;
	return &udma->used_len;
}

static u32 *get_dma_buffer(int fd, void *key,
			   struct iovec iov[], unsigned int *num, u32 *irq)
{
	u32 buf[] = { LHREQ_GETDMA, (u32)key };
	unsigned long udma;
	u32 *res;

	udma = write(fd, buf, sizeof(buf));
	if (udma == (unsigned long)-1)
		return NULL;

	/* Kernel stashes irq in ->used_len. */
	res = dma2iov(udma, iov, num);
	*irq = *res;
	return res;
}

static void trigger_irq(int fd, u32 irq)
{
	u32 buf[] = { LHREQ_IRQ, irq };
	if (write(fd, buf, sizeof(buf)) != 0)
		err(1, "Triggering irq %i", irq);
}

static void discard_iovec(struct iovec *iov, unsigned int *num)
{
	static char discard_buf[1024];
	*num = 1;
	iov->iov_base = discard_buf;
	iov->iov_len = sizeof(discard_buf);
}

static struct termios orig_term;
static void restore_term(void)
{
	tcsetattr(STDIN_FILENO, TCSANOW, &orig_term);
}

struct console_abort
{
	int count;
	struct timeval start;
};

/* We DMA input to buffer bound at start of console page. */
static bool handle_console_input(int fd, struct device *dev)
{
	u32 irq = 0, *lenp;
	int len;
	unsigned int num;
	struct iovec iov[LGUEST_MAX_DMA_SECTIONS];
	struct console_abort *abort = dev->priv;

	lenp = get_dma_buffer(fd, dev->mem, iov, &num, &irq);
	if (!lenp) {
		warn("console: no dma buffer!");
		discard_iovec(iov, &num);
	}

	len = readv(dev->fd, iov, num);
	if (len <= 0) {
		warnx("Failed to get console input, ignoring console.");
		len = 0;
	}

	if (lenp) {
		*lenp = len;
		trigger_irq(fd, irq);
	}

	/* Three ^C within one second?  Exit. */
	if (len == 1 && ((char *)iov[0].iov_base)[0] == 3) {
		if (!abort->count++)
			gettimeofday(&abort->start, NULL);
		else if (abort->count == 3) {
			struct timeval now;
			gettimeofday(&now, NULL);
			if (now.tv_sec <= abort->start.tv_sec+1) {
				/* Make sure waker is not blocked in BREAK */
				u32 args[] = { LHREQ_BREAK, 0 };
				close(waker_fd);
				write(fd, args, sizeof(args));
				exit(2);
			}
			abort->count = 0;
		}
	} else
		abort->count = 0;

	if (!len) {
		restore_term();
		return false;
	}
	return true;
}

static u32 handle_console_output(int fd, const struct iovec *iov,
				 unsigned num, struct device*dev)
{
	return writev(STDOUT_FILENO, iov, num);
}

static u32 handle_tun_output(int fd, const struct iovec *iov,
			     unsigned num, struct device *dev)
{
	/* Now we've seen output, we should warn if we can't get buffers. */
	*(bool *)dev->priv = true;
	return writev(dev->fd, iov, num);
}

static unsigned long peer_offset(unsigned int peernum)
{
	return 4 * peernum;
}

static bool handle_tun_input(int fd, struct device *dev)
{
	u32 irq = 0, *lenp;
	int len;
	unsigned num;
	struct iovec iov[LGUEST_MAX_DMA_SECTIONS];

	lenp = get_dma_buffer(fd, dev->mem+peer_offset(NET_PEERNUM), iov, &num,
			      &irq);
	if (!lenp) {
		if (*(bool *)dev->priv)
			warn("network: no dma buffer!");
		discard_iovec(iov, &num);
	}

	len = readv(dev->fd, iov, num);
	if (len <= 0)
		err(1, "reading network");
	if (lenp) {
		*lenp = len;
		trigger_irq(fd, irq);
	}
	verbose("tun input packet len %i [%02x %02x] (%s)\n", len,
		((u8 *)iov[0].iov_base)[0], ((u8 *)iov[0].iov_base)[1],
		lenp ? "sent" : "discarded");
	return true;
}

static u32 handle_block_output(int fd, const struct iovec *iov,
			       unsigned num, struct device *dev)
{
	struct lguest_block_page *p = dev->mem;
	u32 irq, *lenp;
	unsigned int len, reply_num;
	struct iovec reply[LGUEST_MAX_DMA_SECTIONS];
	off64_t device_len, off = (off64_t)p->sector * 512;

	device_len = *(off64_t *)dev->priv;

	if (off >= device_len)
		err(1, "Bad offset %llu vs %llu", off, device_len);
	if (lseek64(dev->fd, off, SEEK_SET) != off)
		err(1, "Bad seek to sector %i", p->sector);

	verbose("Block: %s at offset %llu\n", p->type ? "WRITE" : "READ", off);

	lenp = get_dma_buffer(fd, dev->mem, reply, &reply_num, &irq);
	if (!lenp)
		err(1, "Block request didn't give us a dma buffer");

	if (p->type) {
		len = writev(dev->fd, iov, num);
		if (off + len > device_len) {
			ftruncate(dev->fd, device_len);
			errx(1, "Write past end %llu+%u", off, len);
		}
		*lenp = 0;
	} else {
		len = readv(dev->fd, reply, reply_num);
		*lenp = len;
	}

	p->result = 1 + (p->bytes != len);
	trigger_irq(fd, irq);
	return 0;
}

static void handle_output(int fd, unsigned long dma, unsigned long key,
			  struct device_list *devices)
{
	struct device *i;
	u32 *lenp;
	struct iovec iov[LGUEST_MAX_DMA_SECTIONS];
	unsigned num = 0;

	lenp = dma2iov(dma, iov, &num);
	for (i = devices->dev; i; i = i->next) {
		if (i->handle_output && key == i->watch_key) {
			*lenp = i->handle_output(fd, iov, num, i);
			return;
		}
	}
	warnx("Pending dma %p, key %p", (void *)dma, (void *)key);
}

static void handle_input(int fd, struct device_list *devices)
{
	struct timeval poll = { .tv_sec = 0, .tv_usec = 0 };

	for (;;) {
		struct device *i;
		fd_set fds = devices->infds;

		if (select(devices->max_infd+1, &fds, NULL, NULL, &poll) == 0)
			break;

		for (i = devices->dev; i; i = i->next) {
			if (i->handle_input && FD_ISSET(i->fd, &fds)) {
				if (!i->handle_input(fd, i)) {
					FD_CLR(i->fd, &devices->infds);
					/* Tell waker to ignore it too... */
					write(waker_fd, &i->fd, sizeof(i->fd));
				}
			}
		}
	}
}

static struct lguest_device_desc *
new_dev_desc(struct lguest_device_desc *descs,
	     u16 type, u16 features, u16 num_pages)
{
	unsigned int i;

	for (i = 0; i < LGUEST_MAX_DEVICES; i++) {
		if (!descs[i].type) {
			descs[i].type = type;
			descs[i].features = features;
			descs[i].num_pages = num_pages;
			if (num_pages) {
				map_zeroed_pages(top, num_pages);
				descs[i].pfn = top/getpagesize();
				top += num_pages*getpagesize();
			}
			return &descs[i];
		}
	}
	errx(1, "too many devices");
}

static struct device *new_device(struct device_list *devices,
				 u16 type, u16 num_pages, u16 features,
				 int fd,
				 bool (*handle_input)(int, struct device *),
				 unsigned long watch_off,
				 u32 (*handle_output)(int,
						      const struct iovec *,
						      unsigned,
						      struct device *))
{
	struct device *dev = malloc(sizeof(*dev));

	/* Append to device list. */
	*devices->lastdev = dev;
	dev->next = NULL;
	devices->lastdev = &dev->next;

	dev->fd = fd;
	if (handle_input)
		set_fd(dev->fd, devices);
	dev->desc = new_dev_desc(devices->descs, type, features, num_pages);
	dev->mem = (void *)(dev->desc->pfn * getpagesize());
	dev->handle_input = handle_input;
	dev->watch_key = (unsigned long)dev->mem + watch_off;
	dev->handle_output = handle_output;
	return dev;
}

static void setup_console(struct device_list *devices)
{
	struct device *dev;

	if (tcgetattr(STDIN_FILENO, &orig_term) == 0) {
		struct termios term = orig_term;
		term.c_lflag &= ~(ISIG|ICANON|ECHO);
		tcsetattr(STDIN_FILENO, TCSANOW, &term);
		atexit(restore_term);
	}

	/* We don't currently require a page for the console. */
	dev = new_device(devices, LGUEST_DEVICE_T_CONSOLE, 0, 0,
			 STDIN_FILENO, handle_console_input,
			 LGUEST_CONSOLE_DMA_KEY, handle_console_output);
	dev->priv = malloc(sizeof(struct console_abort));
	((struct console_abort *)dev->priv)->count = 0;
	verbose("device %p: console\n",
		(void *)(dev->desc->pfn * getpagesize()));
}

static void setup_block_file(const char *filename, struct device_list *devices)
{
	int fd;
	struct device *dev;
	off64_t *device_len;
	struct lguest_block_page *p;

	fd = open_or_die(filename, O_RDWR|O_LARGEFILE|O_DIRECT);
	dev = new_device(devices, LGUEST_DEVICE_T_BLOCK, 1,
			 LGUEST_DEVICE_F_RANDOMNESS,
			 fd, NULL, 0, handle_block_output);
	device_len = dev->priv = malloc(sizeof(*device_len));
	*device_len = lseek64(fd, 0, SEEK_END);
	p = dev->mem;

	p->num_sectors = *device_len/512;
	verbose("device %p: block %i sectors\n",
		(void *)(dev->desc->pfn * getpagesize()), p->num_sectors);
}

/* We use fnctl locks to reserve network slots (autocleanup!) */
static unsigned int find_slot(int netfd, const char *filename)
{
	struct flock fl;

	fl.l_type = F_WRLCK;
	fl.l_whence = SEEK_SET;
	fl.l_len = 1;
	for (fl.l_start = 0;
	     fl.l_start < getpagesize()/sizeof(struct lguest_net);
	     fl.l_start++) {
		if (fcntl(netfd, F_SETLK, &fl) == 0)
			return fl.l_start;
	}
	errx(1, "No free slots in network file %s", filename);
}

static void setup_net_file(const char *filename,
			   struct device_list *devices)
{
	int netfd;
	struct device *dev;

	netfd = open(filename, O_RDWR, 0);
	if (netfd < 0) {
		if (errno == ENOENT) {
			netfd = open(filename, O_RDWR|O_CREAT, 0600);
			if (netfd >= 0) {
				char page[getpagesize()];
				memset(page, 0, sizeof(page));
				write(netfd, page, sizeof(page));
			}
		}
		if (netfd < 0)
			err(1, "cannot open net file '%s'", filename);
	}

	dev = new_device(devices, LGUEST_DEVICE_T_NET, 1,
			 find_slot(netfd, filename)|LGUEST_NET_F_NOCSUM,
			 -1, NULL, 0, NULL);

	/* We overwrite the /dev/zero mapping with the actual file. */
	if (mmap(dev->mem, getpagesize(), PROT_READ|PROT_WRITE,
			 MAP_FIXED|MAP_SHARED, netfd, 0) != dev->mem)
			err(1, "could not mmap '%s'", filename);
	verbose("device %p: shared net %s, peer %i\n",
		(void *)(dev->desc->pfn * getpagesize()), filename,
		dev->desc->features & ~LGUEST_NET_F_NOCSUM);
}

static u32 str2ip(const char *ipaddr)
{
	unsigned int byte[4];

	sscanf(ipaddr, "%u.%u.%u.%u", &byte[0], &byte[1], &byte[2], &byte[3]);
	return (byte[0] << 24) | (byte[1] << 16) | (byte[2] << 8) | byte[3];
}

/* adapted from libbridge */
static void add_to_bridge(int fd, const char *if_name, const char *br_name)
{
	int ifidx;
	struct ifreq ifr;

	if (!*br_name)
		errx(1, "must specify bridge name");

	ifidx = if_nametoindex(if_name);
	if (!ifidx)
		errx(1, "interface %s does not exist!", if_name);

	strncpy(ifr.ifr_name, br_name, IFNAMSIZ);
	ifr.ifr_ifindex = ifidx;
	if (ioctl(fd, SIOCBRADDIF, &ifr) < 0)
		err(1, "can't add %s to bridge %s", if_name, br_name);
}

static void configure_device(int fd, const char *devname, u32 ipaddr,
			     unsigned char hwaddr[6])
{
	struct ifreq ifr;
	struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr;

	memset(&ifr, 0, sizeof(ifr));
	strcpy(ifr.ifr_name, devname);
	sin->sin_family = AF_INET;
	sin->sin_addr.s_addr = htonl(ipaddr);
	if (ioctl(fd, SIOCSIFADDR, &ifr) != 0)
		err(1, "Setting %s interface address", devname);
	ifr.ifr_flags = IFF_UP;
	if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0)
		err(1, "Bringing interface %s up", devname);

	if (ioctl(fd, SIOCGIFHWADDR, &ifr) != 0)
		err(1, "getting hw address for %s", devname);

	memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, 6);
}

static void setup_tun_net(const char *arg, struct device_list *devices)
{
	struct device *dev;
	struct ifreq ifr;
	int netfd, ipfd;
	u32 ip;
	const char *br_name = NULL;

	netfd = open_or_die("/dev/net/tun", O_RDWR);
	memset(&ifr, 0, sizeof(ifr));
	ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
	strcpy(ifr.ifr_name, "tap%d");
	if (ioctl(netfd, TUNSETIFF, &ifr) != 0)
		err(1, "configuring /dev/net/tun");
	ioctl(netfd, TUNSETNOCSUM, 1);

	/* You will be peer 1: we should create enough jitter to randomize */
	dev = new_device(devices, LGUEST_DEVICE_T_NET, 1,
			 NET_PEERNUM|LGUEST_DEVICE_F_RANDOMNESS, netfd,
			 handle_tun_input, peer_offset(0), handle_tun_output);
	dev->priv = malloc(sizeof(bool));
	*(bool *)dev->priv = false;

	ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
	if (ipfd < 0)
		err(1, "opening IP socket");

	if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) {
		ip = INADDR_ANY;
		br_name = arg + strlen(BRIDGE_PFX);
		add_to_bridge(ipfd, ifr.ifr_name, br_name);
	} else
		ip = str2ip(arg);

	/* We are peer 0, ie. first slot. */
	configure_device(ipfd, ifr.ifr_name, ip, dev->mem);

	/* Set "promisc" bit: we want every single packet. */
	*((u8 *)dev->mem) |= 0x1;

	close(ipfd);

	verbose("device %p: tun net %u.%u.%u.%u\n",
		(void *)(dev->desc->pfn * getpagesize()),
		(u8)(ip>>24), (u8)(ip>>16), (u8)(ip>>8), (u8)ip);
	if (br_name)
		verbose("attached to bridge: %s\n", br_name);
}

static void __attribute__((noreturn))
run_guest(int lguest_fd, struct device_list *device_list)
{
	for (;;) {
		u32 args[] = { LHREQ_BREAK, 0 };
		unsigned long arr[2];
		int readval;

		/* We read from the /dev/lguest device to run the Guest. */
		readval = read(lguest_fd, arr, sizeof(arr));

		if (readval == sizeof(arr)) {
			handle_output(lguest_fd, arr[0], arr[1], device_list);
			continue;
		} else if (errno == ENOENT) {
			char reason[1024] = { 0 };
			read(lguest_fd, reason, sizeof(reason)-1);
			errx(1, "%s", reason);
		} else if (errno != EAGAIN)
			err(1, "Running guest failed");
		handle_input(lguest_fd, device_list);
		if (write(lguest_fd, args, sizeof(args)) < 0)
			err(1, "Resetting break");
	}
}

static struct option opts[] = {
	{ "verbose", 0, NULL, 'v' },
	{ "sharenet", 1, NULL, 's' },
	{ "tunnet", 1, NULL, 't' },
	{ "block", 1, NULL, 'b' },
	{ "initrd", 1, NULL, 'i' },
	{ NULL },
};
static void usage(void)
{
	errx(1, "Usage: lguest [--verbose] "
	     "[--sharenet=<filename>|--tunnet=(<ipaddr>|bridge:<bridgename>)\n"
	     "|--block=<filename>|--initrd=<filename>]...\n"
	     "<mem-in-mb> vmlinux [args...]");
}

int main(int argc, char *argv[])
{
	unsigned long mem = 0, pgdir, start, page_offset, initrd_size = 0;
	int i, c, lguest_fd;
	struct device_list device_list;
	void *boot = (void *)0;
	const char *initrd_name = NULL;

	device_list.max_infd = -1;
	device_list.dev = NULL;
	device_list.lastdev = &device_list.dev;
	FD_ZERO(&device_list.infds);

	/* We need to know how much memory so we can allocate devices. */
	for (i = 1; i < argc; i++) {
		if (argv[i][0] != '-') {
			mem = top = atoi(argv[i]) * 1024 * 1024;
			device_list.descs = map_zeroed_pages(top, 1);
			top += getpagesize();
			break;
		}
	}
	while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) {
		switch (c) {
		case 'v':
			verbose = true;
			break;
		case 's':
			setup_net_file(optarg, &device_list);
			break;
		case 't':
			setup_tun_net(optarg, &device_list);
			break;
		case 'b':
			setup_block_file(optarg, &device_list);
			break;
		case 'i':
			initrd_name = optarg;
			break;
		default:
			warnx("Unknown argument %s", argv[optind]);
			usage();
		}
	}
	if (optind + 2 > argc)
		usage();

	/* We need a console device */
	setup_console(&device_list);

	/* First we map /dev/zero over all of guest-physical memory. */
	map_zeroed_pages(0, mem / getpagesize());

	/* Now we load the kernel */
	start = load_kernel(open_or_die(argv[optind+1], O_RDONLY),
			    &page_offset);

	/* Map the initrd image if requested */
	if (initrd_name) {
		initrd_size = load_initrd(initrd_name, mem);
		*(unsigned long *)(boot+0x218) = mem - initrd_size;
		*(unsigned long *)(boot+0x21c) = initrd_size;
		*(unsigned char *)(boot+0x210) = 0xFF;
	}

	/* Set up the initial linar pagetables. */
	pgdir = setup_pagetables(mem, initrd_size, page_offset);

	/* E820 memory map: ours is a simple, single region. */
	*(char*)(boot+E820NR) = 1;
	*((struct e820entry *)(boot+E820MAP))
		= ((struct e820entry) { 0, mem, E820_RAM });
	/* Command line pointer and command line (at 4096) */
	*(void **)(boot + 0x228) = boot + 4096;
	concat(boot + 4096, argv+optind+2);
	/* Paravirt type: 1 == lguest */
	*(int *)(boot + 0x23c) = 1;

	lguest_fd = tell_kernel(pgdir, start, page_offset);
	waker_fd = setup_waker(lguest_fd, &device_list);

	run_guest(lguest_fd, &device_list);
}