path: root/sys/kern/kern_subr.c

/*	$OpenBSD: kern_subr.c,v 1.52 2023/01/31 15:18:56 deraadt Exp $	*/
/*	$NetBSD: kern_subr.c,v 1.15 1996/04/09 17:21:56 ragge Exp $	*/

/*
 * Copyright (c) 1982, 1986, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)kern_subr.c	8.3 (Berkeley) 1/21/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <uvm/uvm_extern.h>

#ifdef PMAP_CHECK_COPYIN

static inline int check_copyin(struct proc *, const void *, size_t);
extern int _copyinstr(const void *, void *, size_t, size_t *);
extern int _copyin(const void *uaddr, void *kaddr, size_t len);

/*
 * If range overlaps an check_copyin region, return EFAULT
 */
static inline int
check_copyin(struct proc *p, const void *vstart, size_t len)
{
	struct vm_map *map = &p->p_vmspace->vm_map;
	const vaddr_t start = (vaddr_t)vstart;
	const vaddr_t end = start + len;
	int i, max;

	/* XXX if the array was sorted, we could shortcut */
	max = map->check_copyin_count;
	membar_consumer();
	for (i = 0; i < max; i++) {
		vaddr_t s = map->check_copyin[i].start;
		vaddr_t e = map->check_copyin[i].end;
		if ((start >= s && start < e) || (end > s && end < e))
			return EFAULT;
	}
	return (0);
}

int
copyinstr(const void *uaddr, void *kaddr, size_t len, size_t *done)
{
	size_t alen;
	int error;

	/*
	 * Must do the copyin checks after figuring out the string length,
	 * the buffer size length may cross into another ELF segment
	 */
	error = _copyinstr(uaddr, kaddr, len, &alen);
	if (PMAP_CHECK_COPYIN && error == 0)
		error = check_copyin(curproc, uaddr, alen);
	if (done)
		*done = alen;
	return (error);
}

int
copyin(const void *uaddr, void *kaddr, size_t len)
{
	int error = 0;

	if (PMAP_CHECK_COPYIN)
		error = check_copyin(curproc, uaddr, len);
	if (error == 0)
		error = _copyin(uaddr, kaddr, len);
	return (error);
}
#endif /* PMAP_CHECK_COPYIN */

int
uiomove(void *cp, size_t n, struct uio *uio)
{
	struct iovec *iov;
	size_t cnt;
	int error = 0;

#ifdef DIAGNOSTIC
	if (uio->uio_rw != UIO_READ && uio->uio_rw != UIO_WRITE)
		panic("uiomove: mode");
	if (uio->uio_segflg == UIO_USERSPACE && uio->uio_procp != curproc)
		panic("uiomove: proc");
#endif

	if (n > uio->uio_resid)
		n = uio->uio_resid;

	while (n > 0) {
		iov = uio->uio_iov;
		cnt = iov->iov_len;
		if (cnt == 0) {
			KASSERT(uio->uio_iovcnt > 0);
			uio->uio_iov++;
			uio->uio_iovcnt--;
			continue;
		}
		if (cnt > n)
			cnt = n;
		switch (uio->uio_segflg) {

		case UIO_USERSPACE:
			sched_pause(preempt);
			if (uio->uio_rw == UIO_READ)
				error = copyout(cp, iov->iov_base, cnt);
			else
				error = copyin(iov->iov_base, cp, cnt);
			if (error)
				return (error);
			break;

		case UIO_SYSSPACE:
			if (uio->uio_rw == UIO_READ)
				error = kcopy(cp, iov->iov_base, cnt);
			else
				error = kcopy(iov->iov_base, cp, cnt);
			if (error)
				return(error);
		}
		iov->iov_base = (caddr_t)iov->iov_base + cnt;
		iov->iov_len -= cnt;
		uio->uio_resid -= cnt;
		uio->uio_offset += cnt;
		cp = (caddr_t)cp + cnt;
		n -= cnt;
	}
	return (error);
}

/*
 * Give next character to user as result of read.
 */
int
ureadc(int c, struct uio *uio)
{
	struct iovec *iov;

	if (uio->uio_resid == 0)
#ifdef DIAGNOSTIC
		panic("ureadc: zero resid");
#else
		return (EINVAL);
#endif
again:
	if (uio->uio_iovcnt <= 0)
#ifdef DIAGNOSTIC
		panic("ureadc: non-positive iovcnt");
#else
		return (EINVAL);
#endif
	iov = uio->uio_iov;
	if (iov->iov_len <= 0) {
		uio->uio_iovcnt--;
		uio->uio_iov++;
		goto again;
	}
	switch (uio->uio_segflg) {

	case UIO_USERSPACE:
	{
		char tmp = c;

		if (copyout(&tmp, iov->iov_base, sizeof(char)) != 0)
			return (EFAULT);
	}
		break;

	case UIO_SYSSPACE:
		*(char *)iov->iov_base = c;
		break;
	}
	iov->iov_base = (caddr_t)iov->iov_base + 1;
	iov->iov_len--;
	uio->uio_resid--;
	uio->uio_offset++;
	return (0);
}

/*
 * General routine to allocate a hash table.
 */
void *
hashinit(int elements, int type, int flags, u_long *hashmask)
{
	u_long hashsize, i;
	LIST_HEAD(generic, generic) *hashtbl;

	if (elements <= 0)
		panic("hashinit: bad cnt");
	if ((elements & (elements - 1)) == 0)
		hashsize = elements;
	else
		for (hashsize = 1; hashsize < elements; hashsize <<= 1)
			continue;
	hashtbl = mallocarray(hashsize, sizeof(*hashtbl), type, flags);
	if (hashtbl == NULL)
		return NULL;
	for (i = 0; i < hashsize; i++)
		LIST_INIT(&hashtbl[i]);
	*hashmask = hashsize - 1;
	return (hashtbl);
}

void
hashfree(void *hash, int elements, int type)
{
	u_long hashsize;
	LIST_HEAD(generic, generic) *hashtbl = hash;

	if (elements <= 0)
		panic("hashfree: bad cnt");
	if ((elements & (elements - 1)) == 0)
		hashsize = elements;
	else
		for (hashsize = 1; hashsize < elements; hashsize <<= 1)
			continue;

	free(hashtbl, type, sizeof(*hashtbl) * hashsize);
}

/*
 * "startup hook" types, functions, and variables.
 */

struct hook_desc_head startuphook_list =
    TAILQ_HEAD_INITIALIZER(startuphook_list);

void *
hook_establish(struct hook_desc_head *head, int tail, void (*fn)(void *),
    void *arg)
{
	struct hook_desc *hdp;

	hdp = malloc(sizeof(*hdp), M_DEVBUF, M_NOWAIT);
	if (hdp == NULL)
		return (NULL);

	hdp->hd_fn = fn;
	hdp->hd_arg = arg;
	if (tail)
		TAILQ_INSERT_TAIL(head, hdp, hd_list);
	else
		TAILQ_INSERT_HEAD(head, hdp, hd_list);

	return (hdp);
}

void
hook_disestablish(struct hook_desc_head *head, void *vhook)
{
	struct hook_desc *hdp;

#ifdef DIAGNOSTIC
	for (hdp = TAILQ_FIRST(head); hdp != NULL;
	    hdp = TAILQ_NEXT(hdp, hd_list))
                if (hdp == vhook)
			break;
	if (hdp == NULL)
		return;
#endif
	hdp = vhook;
	TAILQ_REMOVE(head, hdp, hd_list);
	free(hdp, M_DEVBUF, sizeof(*hdp));
}

/*
 * Run hooks.  Startup hooks are invoked right after scheduler_start but
 * before root is mounted.  Shutdown hooks are invoked immediately before the
 * system is halted or rebooted, i.e. after file systems unmounted,
 * after crash dump done, etc.
 */
void
dohooks(struct hook_desc_head *head, int flags)
{
	struct hook_desc *hdp, *hdp_temp;

	if ((flags & HOOK_REMOVE) == 0) {
		TAILQ_FOREACH_SAFE(hdp, head, hd_list, hdp_temp) {
			(*hdp->hd_fn)(hdp->hd_arg);
		}
	} else {
		while ((hdp = TAILQ_FIRST(head)) != NULL) {
			TAILQ_REMOVE(head, hdp, hd_list);
			(*hdp->hd_fn)(hdp->hd_arg);
			if ((flags & HOOK_FREE) != 0)
				free(hdp, M_DEVBUF, sizeof(*hdp));
		}
	}
}