kvm_getswapinfo.c revision 166550 
1/*
2 * Copyright (c) 1999, Matthew Dillon.  All Rights Reserved.
3 * Copyright (c) 2001, Thomas Moestl.  All Rights Reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/lib/libkvm/kvm_getswapinfo.c 166550 2007-02-07 17:43:11Z jhb $");
29
30#include <sys/param.h>
31#include <sys/time.h>
32#include <sys/stat.h>
33#include <sys/blist.h>
34#include <sys/sysctl.h>
35
36#include <vm/swap_pager.h>
37#include <vm/vm_param.h>
38
39#include <err.h>
40#include <errno.h>
41#include <fcntl.h>
42#include <kvm.h>
43#include <nlist.h>
44#include <paths.h>
45#include <stdio.h>
46#include <stdlib.h>
47#include <string.h>
48#include <unistd.h>
49#include <limits.h>
50
51#include "kvm_private.h"
52
53static struct nlist kvm_swap_nl[] = {
54	{ "_swtailq" },		/* list of swap devices and sizes */
55	{ "_dmmax" },		/* maximum size of a swap block */
56	{ NULL }
57};
58
59#define NL_SWTAILQ	0
60#define NL_DMMAX	1
61
62static int kvm_swap_nl_cached = 0;
63static int unswdev;  /* number of found swap dev's */
64static int dmmax;
65
66static int  kvm_getswapinfo_kvm(kvm_t *, struct kvm_swap *, int, int);
67static int  kvm_getswapinfo_sysctl(kvm_t *, struct kvm_swap *, int, int);
68static int  nlist_init(kvm_t *);
69static int  getsysctl(kvm_t *, char *, void *, size_t);
70
71#define KREAD(kd, addr, obj) \
72	(kvm_read(kd, addr, (char *)(obj), sizeof(*obj)) != sizeof(*obj))
73#define	KGET(idx, var)							\
74	KGET2(kvm_swap_nl[(idx)].n_value, var, kvm_swap_nl[(idx)].n_name)
75#define KGET2(addr, var, msg)						\
76	if (KREAD(kd, (u_long)(addr), (var))) {				\
77		_kvm_err(kd, kd->program, "cannot read %s", msg);	\
78		return (-1);						\
79	}
80
81#define GETSWDEVNAME(dev, str, flags)					\
82	if (dev == NODEV) {						\
83		strlcpy(str, "[NFS swap]", sizeof(str));		\
84	} else {							\
85		snprintf(						\
86		    str, sizeof(str),"%s%s",				\
87		    ((flags & SWIF_DEV_PREFIX) ? _PATH_DEV : ""),	\
88		    devname(dev, S_IFCHR)				\
89		);							\
90	}
91
92int
93kvm_getswapinfo(
94	kvm_t *kd,
95	struct kvm_swap *swap_ary,
96	int swap_max,
97	int flags
98) {
99
100	/*
101	 * clear cache
102	 */
103	if (kd == NULL) {
104		kvm_swap_nl_cached = 0;
105		return(0);
106	}
107
108	if (ISALIVE(kd)) {
109		return kvm_getswapinfo_sysctl(kd, swap_ary, swap_max, flags);
110	} else {
111		return kvm_getswapinfo_kvm(kd, swap_ary, swap_max, flags);
112	}
113}
114
115int
116kvm_getswapinfo_kvm(
117	kvm_t *kd,
118	struct kvm_swap *swap_ary,
119	int swap_max,
120	int flags
121) {
122	int i, ttl;
123	TAILQ_HEAD(, swdevt) swtailq;
124	struct swdevt *sp, swinfo;
125	struct kvm_swap tot;
126
127	if (!nlist_init(kd))
128		return (-1);
129
130	bzero(&tot, sizeof(tot));
131	KGET(NL_SWTAILQ, &swtailq);
132	sp = TAILQ_FIRST(&swtailq);
133	for (i = 0; sp != NULL; i++) {
134		KGET2(sp, &swinfo, "swinfo");
135		ttl = swinfo.sw_nblks - dmmax;
136		if (i < swap_max - 1) {
137			bzero(&swap_ary[i], sizeof(swap_ary[i]));
138			swap_ary[i].ksw_total = ttl;
139			swap_ary[i].ksw_used = swinfo.sw_used;
140			swap_ary[i].ksw_flags = swinfo.sw_flags;
141			GETSWDEVNAME(swinfo.sw_dev, swap_ary[i].ksw_devname,
142			     flags);
143		}
144		tot.ksw_total += ttl;
145		tot.ksw_used += swinfo.sw_used;
146		sp = TAILQ_NEXT(&swinfo, sw_list);
147	}
148
149	if (i >= swap_max)
150		i = swap_max - 1;
151	if (i >= 0)
152		swap_ary[i] = tot;
153
154        return(i);
155}
156
157#define	GETSYSCTL(kd, name, var)					\
158	    getsysctl(kd, name, &(var), sizeof(var))
159
160/* The maximum MIB length for vm.swap_info and an additional device number */
161#define	SWI_MAXMIB	3
162
163int
164kvm_getswapinfo_sysctl(
165	kvm_t *kd,
166	struct kvm_swap *swap_ary,
167	int swap_max,
168	int flags
169) {
170	int ti, ttl;
171	size_t mibi, len;
172	int soid[SWI_MAXMIB];
173	struct xswdev xsd;
174	struct kvm_swap tot;
175
176	if (!GETSYSCTL(kd, "vm.dmmax", dmmax))
177		return -1;
178
179	mibi = SWI_MAXMIB - 1;
180	if (sysctlnametomib("vm.swap_info", soid, &mibi) == -1) {
181		_kvm_err(kd, kd->program, "sysctlnametomib failed: %s",
182		    strerror(errno));
183		return -1;
184	}
185	bzero(&tot, sizeof(tot));
186	for (unswdev = 0;; unswdev++) {
187		soid[mibi] = unswdev;
188		len = sizeof(xsd);
189		if (sysctl(soid, mibi + 1, &xsd, &len, NULL, 0) == -1) {
190			if (errno == ENOENT)
191				break;
192			_kvm_err(kd, kd->program, "cannot read sysctl: %s.",
193			    strerror(errno));
194			return -1;
195		}
196		if (len != sizeof(xsd)) {
197			_kvm_err(kd, kd->program, "struct xswdev has unexpected "
198			    "size;  kernel and libkvm out of sync?");
199			return -1;
200		}
201		if (xsd.xsw_version != XSWDEV_VERSION) {
202			_kvm_err(kd, kd->program, "struct xswdev version "
203			    "mismatch; kernel and libkvm out of sync?");
204			return -1;
205		}
206
207		ttl = xsd.xsw_nblks - dmmax;
208		if (unswdev < swap_max - 1) {
209			bzero(&swap_ary[unswdev], sizeof(swap_ary[unswdev]));
210			swap_ary[unswdev].ksw_total = ttl;
211			swap_ary[unswdev].ksw_used = xsd.xsw_used;
212			swap_ary[unswdev].ksw_flags = xsd.xsw_flags;
213			GETSWDEVNAME(xsd.xsw_dev, swap_ary[unswdev].ksw_devname,
214			     flags);
215		}
216		tot.ksw_total += ttl;
217		tot.ksw_used += xsd.xsw_used;
218	}
219
220	ti = unswdev;
221	if (ti >= swap_max)
222		ti = swap_max - 1;
223	if (ti >= 0)
224		swap_ary[ti] = tot;
225
226        return(ti);
227}
228
229static int
230nlist_init(kvm_t *kd)
231{
232	TAILQ_HEAD(, swdevt) swtailq;
233	struct swdevt *sp, swinfo;
234
235	if (kvm_swap_nl_cached)
236		return (1);
237
238	if (kvm_nlist(kd, kvm_swap_nl) < 0)
239		return (0);
240
241	/* Required entries */
242	if (kvm_swap_nl[NL_SWTAILQ].n_value == 0) {
243		_kvm_err(kd, kd->program, "unable to find swtailq");
244		return (0);
245	}
246
247	if (kvm_swap_nl[NL_DMMAX].n_value == 0) {
248		_kvm_err(kd, kd->program, "unable to find dmmax");
249		return (0);
250	}
251
252	/* Get globals, type of swap */
253	KGET(NL_DMMAX, &dmmax);
254
255	kvm_swap_nl_cached = 1;
256	return (1);
257}
258
259static int
260getsysctl (
261	kvm_t *kd,
262	char *name,
263	void *ptr,
264	size_t len
265) {
266	size_t nlen = len;
267	if (sysctlbyname(name, ptr, &nlen, NULL, 0) == -1) {
268		_kvm_err(kd, kd->program, "cannot read sysctl %s:%s", name,
269		    strerror(errno));
270		return (0);
271	}
272	if (nlen != len) {
273		_kvm_err(kd, kd->program, "sysctl %s has unexpected size", name);
274		return (0);
275	}
276	return (1);
277}
278