xref: /freebsd/sys/kern/init_main.c (revision 0640d357f29fb1c0daaaffadd0416c5981413afd)
1 /*
2  * Copyright (c) 1995 Terrence R. Lambert
3  * All rights reserved.
4  *
5  * Copyright (c) 1982, 1986, 1989, 1991, 1992, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  * (c) UNIX System Laboratories, Inc.
8  * All or some portions of this file are derived from material licensed
9  * to the University of California by American Telephone and Telegraph
10  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
11  * the permission of UNIX System Laboratories, Inc.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  * 3. All advertising materials mentioning features or use of this software
22  *    must display the following acknowledgement:
23  *	This product includes software developed by the University of
24  *	California, Berkeley and its contributors.
25  * 4. Neither the name of the University nor the names of its contributors
26  *    may be used to endorse or promote products derived from this software
27  *    without specific prior written permission.
28  *
29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39  * SUCH DAMAGE.
40  *
41  *	@(#)init_main.c	8.9 (Berkeley) 1/21/94
42  * $Id: init_main.c,v 1.98 1998/10/09 23:42:47 peter Exp $
43  */
44 
45 #include "opt_devfs.h"
46 
47 #include <sys/param.h>
48 #include <sys/file.h>
49 #include <sys/filedesc.h>
50 #include <sys/kernel.h>
51 #include <sys/mount.h>
52 #include <sys/sysctl.h>
53 #include <sys/proc.h>
54 #include <sys/resourcevar.h>
55 #include <sys/signalvar.h>
56 #include <sys/systm.h>
57 #include <sys/vnode.h>
58 #include <sys/sysent.h>
59 #include <sys/reboot.h>
60 #include <sys/sysproto.h>
61 #include <sys/vmmeter.h>
62 #include <sys/unistd.h>
63 #include <sys/malloc.h>
64 
65 #include <machine/cpu.h>
66 
67 #include <vm/vm.h>
68 #include <vm/vm_param.h>
69 #include <vm/vm_prot.h>
70 #include <sys/lock.h>
71 #include <vm/pmap.h>
72 #include <vm/vm_map.h>
73 #include <sys/user.h>
74 #include <sys/copyright.h>
75 
76 extern struct linker_set	sysinit_set;	/* XXX */
77 
78 extern void __main __P((void));
79 extern void main __P((void *framep));
80 
81 /* Components of the first process -- never freed. */
82 static struct session session0;
83 static struct pgrp pgrp0;
84 struct	proc proc0;
85 static struct pcred cred0;
86 static struct filedesc0 filedesc0;
87 static struct plimit limit0;
88 static struct vmspace vmspace0;
89 struct	proc *initproc;
90 
91 int cmask = CMASK;
92 extern	struct user *proc0paddr;
93 
94 struct	vnode *rootvp;
95 int	boothowto = 0;		/* initialized so that it can be patched */
96 
97 struct	timeval boottime;
98 SYSCTL_STRUCT(_kern, KERN_BOOTTIME, boottime,
99 	CTLFLAG_RD, &boottime, timeval, "");
100 
101 static int shutdowntimeout = 120;
102 SYSCTL_INT(_kern, OID_AUTO, shutdown_timeout,
103 	CTLFLAG_RW, &shutdowntimeout, 0, "");
104 
105 /*
106  * Promiscuous argument pass for start_init()
107  *
108  * This is a kludge because we use a return from main() rather than a call
109  * to a new routine in locore.s to kick the kernel alive from locore.s.
110  */
111 static void	*init_framep;
112 
113 
114 #if __GNUC__ >= 2
115 void __main() {}
116 #endif
117 
118 
119 /*
120  * This ensures that there is at least one entry so that the sysinit_set
121  * symbol is not undefined.  A sybsystem ID of SI_SUB_DUMMY is never
122  * executed.
123  */
124 SYSINIT(placeholder, SI_SUB_DUMMY,SI_ORDER_ANY, NULL, NULL)
125 
126 /*
127  * The sysinit table itself.  Items are checked off as the are run.
128  * If we want to register new sysinit types, add them to newsysinit.
129  */
130 struct sysinit **sysinit = (struct sysinit **)sysinit_set.ls_items;
131 struct sysinit **newsysinit;
132 
133 /*
134  * Merge a new sysinit set into the current set, reallocating it if
135  * necessary.  This can only be called after malloc is running.
136  */
137 void
138 sysinit_add(set)
139 	struct sysinit **set;
140 {
141 	struct sysinit **newset;
142 	struct sysinit **sipp;
143 	struct sysinit **xipp;
144 	int count = 0;
145 
146 	if (newsysinit)
147 		for (sipp = newsysinit; *sipp; sipp++)
148 			count++;
149 	else
150 		for (sipp = sysinit; *sipp; sipp++)
151 			count++;
152 	for (sipp = set; *sipp; sipp++)
153 		count++;
154 	count++;		/* Trailing NULL */
155 	newset = malloc(count * sizeof(*sipp), M_TEMP, M_NOWAIT);
156 	if (newset == NULL)
157 		panic("cannot malloc for sysinit");
158 	xipp = newset;
159 	if (newsysinit)
160 		for (sipp = newsysinit; *sipp; sipp++)
161 			*xipp++ = *sipp;
162 	else
163 		for (sipp = sysinit; *sipp; sipp++)
164 			*xipp++ = *sipp;
165 	for (sipp = set; *sipp; sipp++)
166 		*xipp++ = *sipp;
167 	*xipp = NULL;
168 	if (newsysinit)
169 		free(newsysinit, M_TEMP);
170 	newsysinit = newset;
171 }
172 
173 /*
174  * System startup; initialize the world, create process 0, mount root
175  * filesystem, and fork to create init and pagedaemon.  Most of the
176  * hard work is done in the lower-level initialization routines including
177  * startup(), which does memory initialization and autoconfiguration.
178  *
179  * This allows simple addition of new kernel subsystems that require
180  * boot time initialization.  It also allows substitution of subsystem
181  * (for instance, a scheduler, kernel profiler, or VM system) by object
182  * module.  Finally, it allows for optional "kernel threads".
183  */
184 void
185 main(framep)
186 	void *framep;
187 {
188 
189 	register struct sysinit **sipp;		/* system initialization*/
190 	register struct sysinit **xipp;		/* interior loop of sort*/
191 	register struct sysinit *save;		/* bubble*/
192 
193 	/*
194 	 * Copy the locore.s frame pointer for proc0, this is forked into
195 	 * all other processes.
196 	 */
197 	init_framep = framep;
198 
199 restart:
200 	/*
201 	 * Perform a bubble sort of the system initialization objects by
202 	 * their subsystem (primary key) and order (secondary key).
203 	 */
204 	for (sipp = sysinit; *sipp; sipp++) {
205 		for (xipp = sipp + 1; *xipp; xipp++) {
206 			if ((*sipp)->subsystem < (*xipp)->subsystem ||
207 			     ((*sipp)->subsystem == (*xipp)->subsystem &&
208 			      (*sipp)->order < (*xipp)->order))
209 				continue;	/* skip*/
210 			save = *sipp;
211 			*sipp = *xipp;
212 			*xipp = save;
213 		}
214 	}
215 
216 	/*
217 	 * Traverse the (now) ordered list of system initialization tasks.
218 	 * Perform each task, and continue on to the next task.
219 	 *
220 	 * The last item on the list is expected to be the scheduler,
221 	 * which will not return.
222 	 */
223 	for (sipp = sysinit; *sipp; sipp++) {
224 
225 		if ((*sipp)->subsystem == SI_SUB_DUMMY)
226 			continue;	/* skip dummy task(s)*/
227 
228 		if ((*sipp)->subsystem == SI_SUB_DONE)
229 			continue;
230 
231 		switch( (*sipp)->type) {
232 		case SI_TYPE_DEFAULT:
233 			/* no special processing*/
234 			(*((*sipp)->func))((*sipp)->udata);
235 			break;
236 
237 		case SI_TYPE_KTHREAD:
238 #if !defined(SMP)
239 			/* kernel thread*/
240 			if (fork1(&proc0, RFMEM|RFFDG|RFPROC))
241 				panic("fork kernel thread");
242 			cpu_set_fork_handler(pfind(proc0.p_retval[0]),
243 			    (*sipp)->func, (*sipp)->udata);
244 			break;
245 #endif
246 
247 		case SI_TYPE_KPROCESS:
248 			if (fork1(&proc0, RFFDG|RFPROC))
249 				panic("fork kernel process");
250 			cpu_set_fork_handler(pfind(proc0.p_retval[0]),
251 			    (*sipp)->func, (*sipp)->udata);
252 			break;
253 
254 		default:
255 			panic("init_main: unrecognized init type");
256 		}
257 
258 		/* Check off the one we're just done */
259 		(*sipp)->subsystem = SI_SUB_DONE;
260 
261 		/* Check if we've installed more sysinit items via KLD */
262 		if (newsysinit != NULL) {
263 			if (sysinit != (struct sysinit **)sysinit_set.ls_items)
264 				free(sysinit, M_TEMP);
265 			sysinit = newsysinit;
266 			newsysinit = NULL;
267 			goto restart;
268 		}
269 	}
270 
271 	panic("Shouldn't get here!");
272 	/* NOTREACHED*/
273 }
274 
275 
276 /*
277  * Start a kernel process.  This is called after a fork() call in
278  * main() in the file kern/init_main.c.
279  *
280  * This function is used to start "internal" daemons.
281  */
282 /* ARGSUSED*/
283 void
284 kproc_start(udata)
285 	void *udata;
286 {
287 	struct kproc_desc	*kp = udata;
288 	struct proc		*p = curproc;
289 
290 #ifdef DIAGNOSTIC
291 	printf("Start pid=%d <%s>\n",p->p_pid, kp->arg0);
292 #endif
293 
294 	/* save a global descriptor, if desired*/
295 	if( kp->global_procpp != NULL)
296 		*kp->global_procpp	= p;
297 
298 	/* this is a non-swapped system process*/
299 	p->p_flag |= P_INMEM | P_SYSTEM;
300 
301 	/* set up arg0 for 'ps', et al*/
302 	strcpy( p->p_comm, kp->arg0);
303 
304 	/* call the processes' main()...*/
305 	(*kp->func)();
306 
307 	/* NOTREACHED */
308 	panic("kproc_start: %s", kp->arg0);
309 }
310 
311 
312 /*
313  ***************************************************************************
314  ****
315  **** The following SYSINIT's belong elsewhere, but have not yet
316  **** been moved.
317  ****
318  ***************************************************************************
319  */
320 #ifdef OMIT
321 /*
322  * Handled by vfs_mountroot (bad idea) at this time... should be
323  * done the same as 4.4Lite2.
324  */
325 SYSINIT(swapinit, SI_SUB_SWAP, SI_ORDER_FIRST, swapinit, NULL)
326 #endif	/* OMIT*/
327 
328 static void print_caddr_t __P((void *data));
329 static void
330 print_caddr_t(data)
331 	void *data;
332 {
333 	printf("%s", (char *)data);
334 }
335 SYSINIT(announce, SI_SUB_COPYRIGHT, SI_ORDER_FIRST, print_caddr_t, copyright)
336 
337 
338 /*
339  ***************************************************************************
340  ****
341  **** The two following SYSINT's are proc0 specific glue code.  I am not
342  **** convinced that they can not be safely combined, but their order of
343  **** operation has been maintained as the same as the original init_main.c
344  **** for right now.
345  ****
346  **** These probably belong in init_proc.c or kern_proc.c, since they
347  **** deal with proc0 (the fork template process).
348  ****
349  ***************************************************************************
350  */
351 /* ARGSUSED*/
352 static void proc0_init __P((void *dummy));
353 static void
354 proc0_init(dummy)
355 	void *dummy;
356 {
357 	register struct proc		*p;
358 	register struct filedesc0	*fdp;
359 	register unsigned i;
360 
361 	/*
362 	 * Initialize the current process pointer (curproc) before
363 	 * any possible traps/probes to simplify trap processing.
364 	 */
365 	p = &proc0;
366 	curproc = p;			/* XXX redundant*/
367 
368 	/*
369 	 * Initialize process and pgrp structures.
370 	 */
371 	procinit();
372 
373 	/*
374 	 * Initialize sleep queue hash table
375 	 */
376 	sleepinit();
377 
378 	/*
379 	 * additional VM structures
380 	 */
381 	vm_init2();
382 
383 	/*
384 	 * Create process 0 (the swapper).
385 	 */
386 	LIST_INSERT_HEAD(&allproc, p, p_list);
387 	p->p_pgrp = &pgrp0;
388 	LIST_INSERT_HEAD(PGRPHASH(0), &pgrp0, pg_hash);
389 	LIST_INIT(&pgrp0.pg_members);
390 	LIST_INSERT_HEAD(&pgrp0.pg_members, p, p_pglist);
391 
392 	pgrp0.pg_session = &session0;
393 	session0.s_count = 1;
394 	session0.s_leader = p;
395 
396 	p->p_sysent = &aout_sysvec;
397 
398 	p->p_flag = P_INMEM | P_SYSTEM;
399 	p->p_stat = SRUN;
400 	p->p_nice = NZERO;
401 	p->p_rtprio.type = RTP_PRIO_NORMAL;
402 	p->p_rtprio.prio = 0;
403 
404 /*
405  * Link for kernel based threads
406  */
407 	p->p_peers = 0;
408 	p->p_leader = p;
409 
410 	bcopy("swapper", p->p_comm, sizeof ("swapper"));
411 
412 	/* Create credentials. */
413 	cred0.p_refcnt = 1;
414 	p->p_cred = &cred0;
415 	p->p_ucred = crget();
416 	p->p_ucred->cr_ngroups = 1;	/* group 0 */
417 
418 	/* Create the file descriptor table. */
419 	fdp = &filedesc0;
420 	p->p_fd = &fdp->fd_fd;
421 	fdp->fd_fd.fd_refcnt = 1;
422 	fdp->fd_fd.fd_cmask = cmask;
423 	fdp->fd_fd.fd_ofiles = fdp->fd_dfiles;
424 	fdp->fd_fd.fd_ofileflags = fdp->fd_dfileflags;
425 	fdp->fd_fd.fd_nfiles = NDFILE;
426 
427 	/* Create the limits structures. */
428 	p->p_limit = &limit0;
429 	for (i = 0; i < sizeof(p->p_rlimit)/sizeof(p->p_rlimit[0]); i++)
430 		limit0.pl_rlimit[i].rlim_cur =
431 		    limit0.pl_rlimit[i].rlim_max = RLIM_INFINITY;
432 	limit0.pl_rlimit[RLIMIT_NOFILE].rlim_cur =
433 	    limit0.pl_rlimit[RLIMIT_NOFILE].rlim_max = maxfiles;
434 	limit0.pl_rlimit[RLIMIT_NPROC].rlim_cur =
435 	    limit0.pl_rlimit[RLIMIT_NPROC].rlim_max = maxproc;
436 	i = ptoa(cnt.v_free_count);
437 	limit0.pl_rlimit[RLIMIT_RSS].rlim_max = i;
438 	limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_max = i;
439 	limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_cur = i / 3;
440 	limit0.p_cpulimit = RLIM_INFINITY;
441 	limit0.p_refcnt = 1;
442 
443 
444 	/* Allocate a prototype map so we have something to fork. */
445 	pmap_pinit0(&vmspace0.vm_pmap);
446 	p->p_vmspace = &vmspace0;
447 	vmspace0.vm_refcnt = 1;
448 	vm_map_init(&vmspace0.vm_map, round_page(VM_MIN_ADDRESS),
449 	    trunc_page(VM_MAXUSER_ADDRESS));
450 	vmspace0.vm_map.pmap = &vmspace0.vm_pmap;
451 	p->p_addr = proc0paddr;				/* XXX */
452 
453 #ifndef __alpha__		/* XXX what is this? */
454 #define INCOMPAT_LITES2
455 #ifdef INCOMPAT_LITES2
456 	/*
457 	 * proc0 needs to have a coherent frame base in its stack.
458 	 */
459 	cpu_set_init_frame(p, init_framep);			/* XXX! */
460 #endif	/* INCOMPAT_LITES2*/
461 #endif
462 
463 	/*
464 	 * We continue to place resource usage info and signal
465 	 * actions in the user struct so they're pageable.
466 	 */
467 	p->p_stats = &p->p_addr->u_stats;
468 	p->p_sigacts = &p->p_addr->u_sigacts;
469 
470 	/*
471 	 * Charge root for one process.
472 	 */
473 	(void)chgproccnt(0, 1);
474 
475 	/*
476 	 * Initialize the procfs flags (to 0, of course)
477 	 */
478 	p->p_stops = p->p_stype = p->p_step = 0;
479 
480 }
481 SYSINIT(p0init, SI_SUB_INTRINSIC, SI_ORDER_FIRST, proc0_init, NULL)
482 
483 /* ARGSUSED*/
484 static void proc0_post __P((void *dummy));
485 static void
486 proc0_post(dummy)
487 	void *dummy;
488 {
489 	struct timespec ts;
490 
491 	/*
492 	 * Now can look at time, having had a chance to verify the time
493 	 * from the file system.  Reset p->p_runtime as it may have been
494 	 * munched in mi_switch() after the time got set.  Set
495 	 * p->p_switchtime to be consistent with this unmunching.
496 	 */
497 	microtime(&proc0.p_stats->p_start);
498 	proc0.p_runtime = 0;
499 	microuptime(&proc0.p_switchtime);
500 
501 	/*
502 	 * Give the ``random'' number generator a thump.
503 	 * XXX: Does read_random() contain enough bits to be used here ?
504 	 */
505 	nanotime(&ts);
506 	srandom(ts.tv_sec ^ ts.tv_nsec);
507 
508 	/* Initialize signal state for process 0. */
509 	siginit(&proc0);
510 }
511 SYSINIT(p0post, SI_SUB_INTRINSIC_POST, SI_ORDER_FIRST, proc0_post, NULL)
512 
513 
514 
515 
516 /*
517  ***************************************************************************
518  ****
519  **** The following SYSINIT's and glue code should be moved to the
520  **** respective files on a per subsystem basis.
521  ****
522  ***************************************************************************
523  */
524 
525 /* ARGSUSED */
526 static void root_conf __P((void *dummy));
527 static void
528 root_conf(dummy)
529 	void *dummy;
530 {
531 	cpu_rootconf();
532 }
533 SYSINIT(root_conf, SI_SUB_ROOT_CONF, SI_ORDER_FIRST, root_conf, NULL)
534 
535 /* ARGSUSED*/
536 static void xxx_vfs_root_fdtab __P((void *dummy));
537 static void
538 xxx_vfs_root_fdtab(dummy)
539 	void *dummy;
540 {
541 	register struct filedesc0	*fdp = &filedesc0;
542 
543 	/* Get the vnode for '/'.  Set fdp->fd_fd.fd_cdir to reference it. */
544 	if (VFS_ROOT(mountlist.cqh_first, &rootvnode))
545 		panic("cannot find root vnode");
546 	fdp->fd_fd.fd_cdir = rootvnode;
547 	VREF(fdp->fd_fd.fd_cdir);
548 	VOP_UNLOCK(rootvnode, 0, &proc0);
549 	fdp->fd_fd.fd_rdir = rootvnode;
550 }
551 SYSINIT(retrofit, SI_SUB_ROOT_FDTAB, SI_ORDER_FIRST, xxx_vfs_root_fdtab, NULL)
552 
553 
554 /*
555  ***************************************************************************
556  ****
557  **** The following code probably belongs in another file, like
558  **** kern/init_init.c.  It is here for two reasons only:
559  ****
560  ****	1)	This code returns to startup the system; this is
561  ****		abnormal for a kernel thread.
562  ****	2)	This code promiscuously uses init_frame
563  ****
564  ***************************************************************************
565  */
566 
567 static void kthread_init __P((void *dummy));
568 SYSINIT_KP(init,SI_SUB_KTHREAD_INIT, SI_ORDER_FIRST, kthread_init, NULL)
569 
570 
571 extern void prepare_usermode __P((void));
572 static void start_init __P((struct proc *p));
573 
574 /* ARGSUSED*/
575 static void
576 kthread_init(dummy)
577 	void *dummy;
578 {
579 	/* Create process 1 (init(8)). */
580 	start_init(curproc);
581 
582 	prepare_usermode();
583 
584 	/*
585 	 * This returns to the fork trampoline, then to user mode.
586 	 */
587 	return;
588 }
589 
590 
591 /*
592  * List of paths to try when searching for "init".
593  */
594 static char *initpaths[] = {
595 	"/sbin/init",
596 	"/sbin/oinit",
597 	"/sbin/init.bak",
598 	"/stand/sysinstall",
599 	NULL,
600 };
601 
602 /*
603  * Start the initial user process; try exec'ing each pathname in "initpaths".
604  * The program is invoked with one argument containing the boot flags.
605  */
606 static void
607 start_init(p)
608 	struct proc *p;
609 {
610 	vm_offset_t addr;
611 	struct execve_args args;
612 	int options, i, error;
613 	char **pathp, *path, *ucp, **uap, *arg0, *arg1;
614 
615 	initproc = p;
616 
617 	/*
618 	 * Need just enough stack to hold the faked-up "execve()" arguments.
619 	 */
620 	addr = trunc_page(VM_MAXUSER_ADDRESS - PAGE_SIZE);
621 	if (vm_map_find(&p->p_vmspace->vm_map, NULL, 0, &addr, PAGE_SIZE, FALSE, VM_PROT_ALL, VM_PROT_ALL, 0) != 0)
622 		panic("init: couldn't allocate argument space");
623 	p->p_vmspace->vm_maxsaddr = (caddr_t)addr;
624 	p->p_vmspace->vm_ssize = 1;
625 
626 	for (pathp = &initpaths[0]; (path = *pathp) != NULL; pathp++) {
627 		/*
628 		 * Move out the boot flag argument.
629 		 */
630 		options = 0;
631 		ucp = (char *)USRSTACK;
632 		(void)subyte(--ucp, 0);		/* trailing zero */
633 		if (boothowto & RB_SINGLE) {
634 			(void)subyte(--ucp, 's');
635 			options = 1;
636 		}
637 #ifdef notyet
638                 if (boothowto & RB_FASTBOOT) {
639 			(void)subyte(--ucp, 'f');
640 			options = 1;
641 		}
642 #endif
643 
644 #ifdef BOOTCDROM
645 		(void)subyte(--ucp, 'C');
646 		options = 1;
647 #endif
648 		if (options == 0)
649 			(void)subyte(--ucp, '-');
650 		(void)subyte(--ucp, '-');		/* leading hyphen */
651 		arg1 = ucp;
652 
653 		/*
654 		 * Move out the file name (also arg 0).
655 		 */
656 		for (i = strlen(path) + 1; i >= 0; i--)
657 			(void)subyte(--ucp, path[i]);
658 		arg0 = ucp;
659 
660 		/*
661 		 * Move out the arg pointers.
662 		 */
663 		uap = (char **)((intptr_t)ucp & ~(sizeof(intptr_t)-1));
664 		(void)suword((caddr_t)--uap, (long)0);	/* terminator */
665 		(void)suword((caddr_t)--uap, (long)(intptr_t)arg1);
666 		(void)suword((caddr_t)--uap, (long)(intptr_t)arg0);
667 
668 		/*
669 		 * Point at the arguments.
670 		 */
671 		args.fname = arg0;
672 		args.argv = uap;
673 		args.envv = NULL;
674 
675 		/*
676 		 * Now try to exec the program.  If can't for any reason
677 		 * other than it doesn't exist, complain.
678 		 *
679 		 * Otherwise return to main() which returns to btext
680 		 * which completes the system startup.
681 		 */
682 		if ((error = execve(p, &args)) == 0)
683 			return;
684 		if (error != ENOENT)
685 			printf("exec %s: error %d\n", path, error);
686 	}
687 	printf("init: not found\n");
688 	panic("no init");
689 }
690