1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>
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/cpuset.h>
35#include <sys/kthread.h>
36#include <sys/lock.h>
37#include <sys/mutex.h>
38#include <sys/proc.h>
39#include <sys/resourcevar.h>
40#include <sys/rwlock.h>
41#include <sys/signalvar.h>
42#include <sys/sysent.h>
43#include <sys/sx.h>
44#include <sys/umtx.h>
45#include <sys/unistd.h>
46#include <sys/wait.h>
47#include <sys/sched.h>
48#include <sys/tslog.h>
49#include <vm/vm.h>
50#include <vm/vm_extern.h>
51
52#include <machine/stdarg.h>
53
54/*
55 * Start a kernel process.  This is called after a fork() call in
56 * mi_startup() in the file kern/init_main.c.
57 *
58 * This function is used to start "internal" daemons and intended
59 * to be called from SYSINIT().
60 */
61void
62kproc_start(const void *udata)
63{
64	const struct kproc_desc	*kp = udata;
65	int error;
66
67	error = kproc_create((void (*)(void *))kp->func, NULL,
68		    kp->global_procpp, 0, 0, "%s", kp->arg0);
69	if (error)
70		panic("kproc_start: %s: error %d", kp->arg0, error);
71}
72
73/*
74 * Create a kernel process/thread/whatever.  It shares its address space
75 * with proc0 - ie: kernel only.
76 *
77 * func is the function to start.
78 * arg is the parameter to pass to function on first startup.
79 * newpp is the return value pointing to the thread's struct proc.
80 * flags are flags to fork1 (in unistd.h)
81 * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
82 */
83int
84kproc_create(void (*func)(void *), void *arg,
85    struct proc **newpp, int flags, int pages, const char *fmt, ...)
86{
87	struct fork_req fr;
88	int error;
89	va_list ap;
90	struct thread *td;
91	struct proc *p2;
92
93	if (!proc0.p_stats)
94		panic("kproc_create called too soon");
95
96	bzero(&fr, sizeof(fr));
97	fr.fr_flags = RFMEM | RFFDG | RFPROC | RFSTOPPED | flags;
98	fr.fr_flags2 = FR2_KPROC;
99	fr.fr_pages = pages;
100	fr.fr_procp = &p2;
101	error = fork1(&thread0, &fr);
102	if (error)
103		return error;
104
105	/* save a global descriptor, if desired */
106	if (newpp != NULL)
107		*newpp = p2;
108
109	/* set up arg0 for 'ps', et al */
110	va_start(ap, fmt);
111	vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
112	va_end(ap);
113	td = FIRST_THREAD_IN_PROC(p2);
114	va_start(ap, fmt);
115	vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
116	va_end(ap);
117#ifdef KTR
118	sched_clear_tdname(td);
119#endif
120	TSTHREAD(td, td->td_name);
121#ifdef HWPMC_HOOKS
122	if (PMC_SYSTEM_SAMPLING_ACTIVE()) {
123		PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_PROC_CREATE_LOG, p2);
124		PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_CREATE_LOG, NULL);
125	}
126#endif
127
128	/* call the processes' main()... */
129	cpu_fork_kthread_handler(td, func, arg);
130
131	/* Avoid inheriting affinity from a random parent. */
132	cpuset_kernthread(td);
133	thread_lock(td);
134	TD_SET_CAN_RUN(td);
135	sched_prio(td, PVM);
136	sched_user_prio(td, PUSER);
137
138	/* Delay putting it on the run queue until now. */
139	if (!(flags & RFSTOPPED))
140		sched_add(td, SRQ_BORING);
141	else
142		thread_unlock(td);
143
144	return 0;
145}
146
147void
148kproc_exit(int ecode)
149{
150	struct thread *td;
151	struct proc *p;
152
153	td = curthread;
154	p = td->td_proc;
155
156	/*
157	 * Reparent curthread from proc0 to init so that the zombie
158	 * is harvested.
159	 */
160	sx_xlock(&proctree_lock);
161	PROC_LOCK(p);
162	proc_reparent(p, initproc, true);
163	PROC_UNLOCK(p);
164	sx_xunlock(&proctree_lock);
165
166	/*
167	 * Wakeup anyone waiting for us to exit.
168	 */
169	wakeup(p);
170
171	/* Buh-bye! */
172	exit1(td, ecode, 0);
173}
174
175/*
176 * Advise a kernel process to suspend (or resume) in its main loop.
177 * Participation is voluntary.
178 */
179int
180kproc_suspend(struct proc *p, int timo)
181{
182	/*
183	 * Make sure this is indeed a system process and we can safely
184	 * use the p_siglist field.
185	 */
186	PROC_LOCK(p);
187	if ((p->p_flag & P_KPROC) == 0) {
188		PROC_UNLOCK(p);
189		return (EINVAL);
190	}
191	SIGADDSET(p->p_siglist, SIGSTOP);
192	wakeup(p);
193	return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo);
194}
195
196int
197kproc_resume(struct proc *p)
198{
199	/*
200	 * Make sure this is indeed a system process and we can safely
201	 * use the p_siglist field.
202	 */
203	PROC_LOCK(p);
204	if ((p->p_flag & P_KPROC) == 0) {
205		PROC_UNLOCK(p);
206		return (EINVAL);
207	}
208	SIGDELSET(p->p_siglist, SIGSTOP);
209	PROC_UNLOCK(p);
210	wakeup(&p->p_siglist);
211	return (0);
212}
213
214void
215kproc_suspend_check(struct proc *p)
216{
217	PROC_LOCK(p);
218	while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
219		wakeup(&p->p_siglist);
220		msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
221	}
222	PROC_UNLOCK(p);
223}
224
225/*
226 * Start a kernel thread.
227 *
228 * This function is used to start "internal" daemons and intended
229 * to be called from SYSINIT().
230 */
231
232void
233kthread_start(const void *udata)
234{
235	const struct kthread_desc	*kp = udata;
236	int error;
237
238	error = kthread_add((void (*)(void *))kp->func, NULL,
239		    NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
240	if (error)
241		panic("kthread_start: %s: error %d", kp->arg0, error);
242}
243
244/*
245 * Create a kernel thread.  It shares its address space
246 * with proc0 - ie: kernel only.
247 *
248 * func is the function to start.
249 * arg is the parameter to pass to function on first startup.
250 * newtdp is the return value pointing to the thread's struct thread.
251 *  ** XXX fix this --> flags are flags to fork1 (in unistd.h)
252 * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
253 */
254int
255kthread_add(void (*func)(void *), void *arg, struct proc *p,
256    struct thread **newtdp, int flags, int pages, const char *fmt, ...)
257{
258	va_list ap;
259	struct thread *newtd, *oldtd;
260
261	if (!proc0.p_stats)
262		panic("kthread_add called too soon");
263
264	/* If no process supplied, put it on proc0 */
265	if (p == NULL)
266		p = &proc0;
267
268	/* Initialize our new td  */
269	newtd = thread_alloc(pages);
270	if (newtd == NULL)
271		return (ENOMEM);
272
273	PROC_LOCK(p);
274	oldtd = FIRST_THREAD_IN_PROC(p);
275
276	bzero(&newtd->td_startzero,
277	    __rangeof(struct thread, td_startzero, td_endzero));
278	bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
279	    __rangeof(struct thread, td_startcopy, td_endcopy));
280
281	/* set up arg0 for 'ps', et al */
282	va_start(ap, fmt);
283	vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap);
284	va_end(ap);
285
286	TSTHREAD(newtd, newtd->td_name);
287
288	newtd->td_proc = p;  /* needed for cpu_copy_thread */
289	newtd->td_pflags |= TDP_KTHREAD;
290
291	/* might be further optimized for kthread */
292	cpu_copy_thread(newtd, oldtd);
293
294	/* put the designated function(arg) as the resume context */
295	cpu_fork_kthread_handler(newtd, func, arg);
296
297	thread_cow_get_proc(newtd, p);
298
299	/* this code almost the same as create_thread() in kern_thr.c */
300	p->p_flag |= P_HADTHREADS;
301	thread_link(newtd, p);
302	thread_lock(oldtd);
303	/* let the scheduler know about these things. */
304	sched_fork_thread(oldtd, newtd);
305	TD_SET_CAN_RUN(newtd);
306	thread_unlock(oldtd);
307	PROC_UNLOCK(p);
308
309	tidhash_add(newtd);
310
311	/* Avoid inheriting affinity from a random parent. */
312	cpuset_kernthread(newtd);
313#ifdef HWPMC_HOOKS
314	if (PMC_SYSTEM_SAMPLING_ACTIVE())
315		PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_CREATE_LOG, NULL);
316#endif
317	/* Delay putting it on the run queue until now. */
318	if (!(flags & RFSTOPPED)) {
319		thread_lock(newtd);
320		sched_add(newtd, SRQ_BORING);
321	}
322	if (newtdp)
323		*newtdp = newtd;
324	return 0;
325}
326
327void
328kthread_exit(void)
329{
330	struct proc *p;
331	struct thread *td;
332
333	td = curthread;
334	p = td->td_proc;
335
336#ifdef HWPMC_HOOKS
337	if (PMC_SYSTEM_SAMPLING_ACTIVE())
338		PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL);
339#endif
340	/* A module may be waiting for us to exit. */
341	wakeup(td);
342
343	/*
344	 * The last exiting thread in a kernel process must tear down
345	 * the whole process.
346	 */
347	PROC_LOCK(p);
348	if (p->p_numthreads == 1) {
349		PROC_UNLOCK(p);
350		kproc_exit(0);
351	}
352
353	if (p->p_sysent->sv_ontdexit != NULL)
354		p->p_sysent->sv_ontdexit(td);
355
356	tidhash_remove(td);
357	umtx_thread_exit(td);
358	tdsigcleanup(td);
359	PROC_SLOCK(p);
360	thread_exit();
361}
362
363/*
364 * Advise a kernel process to suspend (or resume) in its main loop.
365 * Participation is voluntary.
366 */
367int
368kthread_suspend(struct thread *td, int timo)
369{
370	struct proc *p;
371
372	p = td->td_proc;
373
374	/*
375	 * td_pflags should not be read by any thread other than
376	 * curthread, but as long as this flag is invariant during the
377	 * thread's lifetime, it is OK to check its state.
378	 */
379	if ((td->td_pflags & TDP_KTHREAD) == 0)
380		return (EINVAL);
381
382	/*
383	 * The caller of the primitive should have already checked that the
384	 * thread is up and running, thus not being blocked by other
385	 * conditions.
386	 */
387	PROC_LOCK(p);
388	thread_lock(td);
389	td->td_flags |= TDF_KTH_SUSP;
390	thread_unlock(td);
391	return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt",
392	    timo));
393}
394
395/*
396 * Resume a thread previously put asleep with kthread_suspend().
397 */
398int
399kthread_resume(struct thread *td)
400{
401	struct proc *p;
402
403	p = td->td_proc;
404
405	/*
406	 * td_pflags should not be read by any thread other than
407	 * curthread, but as long as this flag is invariant during the
408	 * thread's lifetime, it is OK to check its state.
409	 */
410	if ((td->td_pflags & TDP_KTHREAD) == 0)
411		return (EINVAL);
412
413	PROC_LOCK(p);
414	thread_lock(td);
415	td->td_flags &= ~TDF_KTH_SUSP;
416	thread_unlock(td);
417	wakeup(&td->td_flags);
418	PROC_UNLOCK(p);
419	return (0);
420}
421
422/*
423 * Used by the thread to poll as to whether it should yield/sleep
424 * and notify the caller that is has happened.
425 */
426void
427kthread_suspend_check(void)
428{
429	struct proc *p;
430	struct thread *td;
431
432	td = curthread;
433	p = td->td_proc;
434
435	if ((td->td_pflags & TDP_KTHREAD) == 0)
436		panic("%s: curthread is not a valid kthread", __func__);
437
438	/*
439	 * Setting the TDF_KTH_SUSP flag is protected by process lock.
440	 *
441	 * Do an unlocked read first to avoid serializing with all other threads
442	 * in the common case of not suspending.
443	 */
444	if ((td->td_flags & TDF_KTH_SUSP) == 0)
445		return;
446	PROC_LOCK(p);
447	while ((td->td_flags & TDF_KTH_SUSP) != 0) {
448		wakeup(&td->td_flags);
449		msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0);
450	}
451	PROC_UNLOCK(p);
452}
453
454int
455kproc_kthread_add(void (*func)(void *), void *arg,
456            struct proc **procptr, struct thread **tdptr,
457            int flags, int pages, const char *procname, const char *fmt, ...)
458{
459	int error;
460	va_list ap;
461	char buf[100];
462	struct thread *td;
463
464	if (*procptr == NULL) {
465		error = kproc_create(func, arg,
466		    	procptr, flags, pages, "%s", procname);
467		if (error)
468			return (error);
469		td = FIRST_THREAD_IN_PROC(*procptr);
470		if (tdptr)
471			*tdptr = td;
472		va_start(ap, fmt);
473		vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
474		va_end(ap);
475#ifdef KTR
476		sched_clear_tdname(td);
477#endif
478		return (0);
479	}
480	va_start(ap, fmt);
481	vsnprintf(buf, sizeof(buf), fmt, ap);
482	va_end(ap);
483	error = kthread_add(func, arg, *procptr,
484		    tdptr, flags, pages, "%s", buf);
485	return (error);
486}
487