path: root/usr/src/uts/common/os/subr.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright 2019 Joyent, Inc.
 */

/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved	*/

#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/param.h>
#include <sys/vmparam.h>
#include <sys/systm.h>
#include <sys/cred.h>
#include <sys/user.h>
#include <sys/proc.h>
#include <sys/conf.h>
#include <sys/tuneable.h>
#include <sys/cpuvar.h>
#include <sys/archsystm.h>
#include <sys/vmem.h>
#include <vm/seg_kmem.h>
#include <sys/errno.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/atomic.h>
#include <sys/model.h>
#include <sys/kmem.h>
#include <sys/memlist.h>
#include <sys/autoconf.h>
#include <sys/ontrap.h>
#include <sys/utsname.h>
#include <sys/zone.h>

#ifdef __sparc
#include <sys/membar.h>
#endif

/*
 * Routine which sets a user error; placed in
 * illegal entries in the bdevsw and cdevsw tables.
 */

int
nodev()
{
	return (curthread->t_lwp ?
	    ttolwp(curthread)->lwp_error = ENXIO : ENXIO);
}

/*
 * Null routine; placed in insignificant entries
 * in the bdevsw and cdevsw tables.
 */

int
nulldev()
{
	return (0);
}

static kmutex_t udevlock;

/*
 * Generate an unused major device number.
 */
major_t
getudev()
{
	static major_t next = 0;
	major_t ret;

	/*
	 * Ensure that we start allocating major numbers above the 'devcnt'
	 * count.  The only limit we place on the number is that it should be a
	 * legal 32-bit SVR4 major number and be greater than or equal to devcnt
	 * in the current system).
	 */
	mutex_enter(&udevlock);
	if (next == 0)
		next = devcnt;
	if (next <= L_MAXMAJ32 && next >= devcnt)
		ret = next++;
	else {
		/*
		 * If we fail to allocate a major number because devcnt has
		 * reached L_MAXMAJ32, we may be the victim of a sparsely
		 * populated devnames array.  We scan the array backwards
		 * looking for an empty slot;  if we find one, mark it as
		 * DN_GETUDEV so it doesn't get taken by subsequent consumers
		 * users of the devnames array, and issue a warning.
		 * It is vital for this routine to take drastic measures to
		 * succeed, since the kernel really needs it to boot.
		 */
		int i;
		for (i = devcnt - 1; i >= 0; i--) {
			LOCK_DEV_OPS(&devnamesp[i].dn_lock);
			if (devnamesp[i].dn_name == NULL &&
			    ((devnamesp[i].dn_flags & DN_TAKEN_GETUDEV) == 0))
				break;
			UNLOCK_DEV_OPS(&devnamesp[i].dn_lock);
		}
		if (i != -1) {
			cmn_err(CE_WARN, "Reusing device major number %d.", i);
			ASSERT(i >= 0 && i < devcnt);
			devnamesp[i].dn_flags |= DN_TAKEN_GETUDEV;
			UNLOCK_DEV_OPS(&devnamesp[i].dn_lock);
			ret = (major_t)i;
		} else {
			ret = DDI_MAJOR_T_NONE;
		}
	}
	mutex_exit(&udevlock);
	return (ret);
}


/*
 * Compress 'long' device number encoding to 32-bit device number
 * encoding.  If it won't fit, we return failure, but set the
 * device number to 32-bit NODEV for the sake of our callers.
 */
int
cmpldev(dev32_t *dst, dev_t dev)
{
#if defined(_LP64)
	if (dev == NODEV) {
		*dst = NODEV32;
	} else {
		major_t major = dev >> L_BITSMINOR;
		minor_t minor = dev & L_MAXMIN;

		if (major > L_MAXMAJ32 || minor > L_MAXMIN32) {
			*dst = NODEV32;
			return (0);
		}

		*dst = (dev32_t)((major << L_BITSMINOR32) | minor);
	}
#else
	*dst = (dev32_t)dev;
#endif
	return (1);
}

/*
 * Expand 32-bit dev_t's to long dev_t's.  Expansion always "fits"
 * into the return type, but we're careful to expand NODEV explicitly.
 */
dev_t
expldev(dev32_t dev32)
{
#ifdef _LP64
	if (dev32 == NODEV32)
		return (NODEV);
	return (makedevice((dev32 >> L_BITSMINOR32) & L_MAXMAJ32,
	    dev32 & L_MAXMIN32));
#else
	return ((dev_t)dev32);
#endif
}

#ifndef _LP64
/*
 * Keep these entry points for 32-bit systems but enforce the use
 * of MIN/MAX macros on 64-bit systems.  The DDI header files already
 * define min/max as macros so drivers shouldn't need these functions.
 */

int
min(int a, int b)
{
	return (a < b ? a : b);
}

int
max(int a, int b)
{
	return (a > b ? a : b);
}

uint_t
umin(uint_t a, uint_t b)
{
	return (a < b ? a : b);
}

uint_t
umax(uint_t a, uint_t b)
{
	return (a > b ? a : b);
}

#endif /* !_LP64 */

/*
 * Parse suboptions from a string.
 * Same as getsubopt(3C).
 */
int
getsubopt(char **optionsp, char * const *tokens, char **valuep)
{
	char *s = *optionsp, *p;
	int i;
	size_t optlen;

	*valuep = NULL;
	if (*s == '\0')
		return (-1);
	p = strchr(s, ',');		/* find next option */
	if (p == NULL) {
		p = s + strlen(s);
	} else {
		*p++ = '\0';		/* mark end and point to next */
	}
	*optionsp = p;			/* point to next option */
	p = strchr(s, '=');		/* find value */
	if (p == NULL) {
		optlen = strlen(s);
		*valuep = NULL;
	} else {
		optlen = p - s;
		*valuep = ++p;
	}
	for (i = 0; tokens[i] != NULL; i++) {
		if ((optlen == strlen(tokens[i])) &&
		    (strncmp(s, tokens[i], optlen) == 0))
			return (i);
	}
	/* no match, point value at option and return error */
	*valuep = s;
	return (-1);
}

/*
 * Append the suboption string 'opt' starting at the position 'str'
 * within the buffer defined by 'buf' and 'len'. If 'buf' is not null,
 * a comma is appended first.
 * Return a pointer to the end of the resulting string (the null byte).
 * Return NULL if there isn't enough space left to append 'opt'.
 */
char *
append_subopt(const char *buf, size_t len, char *str, const char *opt)
{
	size_t l = strlen(opt);

	/*
	 * Include a ',' if this is not the first option.
	 * Include space for the null byte.
	 */
	if (strlen(buf) + (buf[0] != '\0') + l + 1 > len)
		return (NULL);

	if (buf[0] != '\0')
		*str++ = ',';
	(void) strcpy(str, opt);
	return (str + l);
}

/*
 * Tables to convert a single byte to/from binary-coded decimal (BCD).
 */
uchar_t byte_to_bcd[256] = {
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29,
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99,
};

uchar_t bcd_to_byte[256] = {		/* CSTYLED */
	 0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  0,  0,  0,  0,  0,  0,
	10, 11, 12, 13, 14, 15, 16, 17, 18, 19,  0,  0,  0,  0,  0,  0,
	20, 21, 22, 23, 24, 25, 26, 27, 28, 29,  0,  0,  0,  0,  0,  0,
	30, 31, 32, 33, 34, 35, 36, 37, 38, 39,  0,  0,  0,  0,  0,  0,
	40, 41, 42, 43, 44, 45, 46, 47, 48, 49,  0,  0,  0,  0,  0,  0,
	50, 51, 52, 53, 54, 55, 56, 57, 58, 59,  0,  0,  0,  0,  0,  0,
	60, 61, 62, 63, 64, 65, 66, 67, 68, 69,  0,  0,  0,  0,  0,  0,
	70, 71, 72, 73, 74, 75, 76, 77, 78, 79,  0,  0,  0,  0,  0,  0,
	80, 81, 82, 83, 84, 85, 86, 87, 88, 89,  0,  0,  0,  0,  0,  0,
	90, 91, 92, 93, 94, 95, 96, 97, 98, 99,
};

/*
 * Hot-patch a single instruction in the kernel's text.
 *
 * If you want to patch multiple instructions you must arrange to do it so that
 * all intermediate stages are sane -- we don't stop other cpus while doing
 * this.
 *
 * Size must be 1, 2, or 4 bytes with iaddr aligned accordingly.
 *
 * The instruction itself might straddle a page boundary, so we have to account
 * for that.
 */
void
hot_patch_kernel_text(caddr_t iaddr, uint32_t new_instr, uint_t size)
{
	const uintptr_t pageoff = (uintptr_t)iaddr & PAGEOFFSET;
	const boolean_t straddles = (pageoff + size > PAGESIZE);
	const size_t mapsize = straddles ? PAGESIZE * 2 : PAGESIZE;
	caddr_t ipageaddr = iaddr - pageoff;
	caddr_t vaddr;
	page_t **ppp;

	vaddr = vmem_alloc(heap_arena, mapsize, VM_SLEEP);

	(void) as_pagelock(&kas, &ppp, ipageaddr, mapsize, S_WRITE);

	hat_devload(kas.a_hat, vaddr, PAGESIZE,
	    hat_getpfnum(kas.a_hat, ipageaddr), PROT_READ | PROT_WRITE,
	    HAT_LOAD_LOCK | HAT_LOAD_NOCONSIST);

	if (straddles) {
		hat_devload(kas.a_hat, vaddr + PAGESIZE, PAGESIZE,
		    hat_getpfnum(kas.a_hat, ipageaddr + PAGESIZE),
		    PROT_READ | PROT_WRITE, HAT_LOAD_LOCK | HAT_LOAD_NOCONSIST);
	}

	switch (size) {
	case 1:
		*(uint8_t *)(vaddr + pageoff) = new_instr;
		break;
	case 2:
		*(uint16_t *)(vaddr + pageoff) = new_instr;
		break;
	case 4:
		*(uint32_t *)(vaddr + pageoff) = new_instr;
		break;
	default:
		panic("illegal hot-patch");
	}

	membar_enter();
	sync_icache(vaddr + pageoff, size);
	sync_icache(iaddr, size);
	as_pageunlock(&kas, ppp, ipageaddr, mapsize, S_WRITE);
	hat_unload(kas.a_hat, vaddr, mapsize, HAT_UNLOAD_UNLOCK);
	vmem_free(heap_arena, vaddr, mapsize);
}

/*
 * Routine to report an attempt to execute non-executable data.  If the
 * address executed lies in the stack, explicitly say so.
 */
void
report_stack_exec(proc_t *p, caddr_t addr)
{
	if (!noexec_user_stack_log)
		return;

	if (addr < p->p_usrstack && addr >= (p->p_usrstack - p->p_stksize)) {
		cmn_err(CE_NOTE, "%s[%d] attempt to execute code "
		    "on stack by uid %d", p->p_user.u_comm,
		    p->p_pid, crgetruid(p->p_cred));
	} else {
		cmn_err(CE_NOTE, "%s[%d] attempt to execute non-executable "
		    "data at 0x%p by uid %d", p->p_user.u_comm,
		    p->p_pid, (void *) addr, crgetruid(p->p_cred));
	}

	delay(hz / 50);
}

/*
 * Determine whether the address range [addr, addr + len) is in memlist mp.
 */
int
address_in_memlist(struct memlist *mp, uint64_t addr, size_t len)
{
	while (mp != 0)	 {
		if ((addr >= mp->ml_address) &&
		    (addr + len <= mp->ml_address + mp->ml_size))
			return (1);	 /* TRUE */
		mp = mp->ml_next;
	}
	return (0);	/* FALSE */
}

/*
 * Pop the topmost element from the t_ontrap stack, removing the current set of
 * on_trap() protections.  Refer to <sys/ontrap.h> for more info.  If the
 * stack is already empty, no_trap() just returns.
 */
void
no_trap(void)
{
	if (curthread->t_ontrap != NULL) {
#ifdef __sparc
		membar_sync(); /* deferred error barrier (see sparcv9_subr.s) */
#endif
		curthread->t_ontrap = curthread->t_ontrap->ot_prev;
	}
}

/*
 * Return utsname.nodename outside a zone, or the zone name within.
 */
char *
uts_nodename(void)
{
	if (curproc == NULL)
		return (utsname.nodename);
	return (curproc->p_zone->zone_nodename);
}