sym.c revision 270315 
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright (c) 1997-1999 by Sun Microsystems, Inc.
24 * All rights reserved.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29#include <stdio.h>
30#include <fcntl.h>
31#include <ctype.h>
32#include <string.h>
33#include <signal.h>
34#include <errno.h>
35#include <stdlib.h>
36#include <stdarg.h>
37#include <unistd.h>
38#include <limits.h>
39#include <sys/types.h>
40#include <sys/stat.h>
41
42#include <libelf.h>
43#include <link.h>
44#include <elf.h>
45#if defined(sun)
46#include <sys/machelf.h>
47
48#include <kstat.h>
49#else
50/* FreeBSD */
51#include <sys/elf.h>
52#include <sys/ksyms.h>
53#include <sys/param.h>
54#include <sys/module.h>
55#include <sys/linker.h>
56#endif
57#include <sys/cpuvar.h>
58
59typedef struct syment {
60	uintptr_t	addr;
61	char		*name;
62	size_t		size;
63} syment_t;
64
65static syment_t *symbol_table;
66static int nsyms, maxsyms;
67static char maxsymname[64];
68
69#if defined(sun)
70#ifdef _ELF64
71#define	elf_getshdr elf64_getshdr
72#else
73#define	elf_getshdr elf32_getshdr
74#endif
75#endif
76
77static void
78add_symbol(char *name, uintptr_t addr, size_t size)
79{
80	syment_t *sep;
81
82	if (nsyms >= maxsyms) {
83		maxsyms += 10000;
84		symbol_table = realloc(symbol_table, maxsyms * sizeof (*sep));
85		if (symbol_table == NULL) {
86			(void) fprintf(stderr, "can't allocate symbol table\n");
87			exit(3);
88		}
89	}
90	sep = &symbol_table[nsyms++];
91
92	sep->name = name;
93	sep->addr = addr;
94	sep->size = size;
95}
96
97static void
98remove_symbol(uintptr_t addr)
99{
100	int i;
101	syment_t *sep = symbol_table;
102
103	for (i = 0; i < nsyms; i++, sep++)
104		if (sep->addr == addr)
105			sep->addr = 0;
106}
107
108#if defined(sun)
109static void
110fake_up_certain_popular_kernel_symbols(void)
111{
112	kstat_ctl_t *kc;
113	kstat_t *ksp;
114	char *name;
115
116	if ((kc = kstat_open()) == NULL)
117		return;
118
119	for (ksp = kc->kc_chain; ksp; ksp = ksp->ks_next) {
120		if (strcmp(ksp->ks_module, "cpu_info") == 0) {
121			if ((name = malloc(20)) == NULL)
122				break;
123			/*
124			 * For consistency, keep cpu[0] and toss cpu0
125			 * or any other such symbols.
126			 */
127			if (ksp->ks_instance == 0)
128				remove_symbol((uintptr_t)ksp->ks_private);
129			(void) sprintf(name, "cpu[%d]", ksp->ks_instance);
130			add_symbol(name, (uintptr_t)ksp->ks_private,
131			    sizeof (struct cpu));
132		}
133	}
134	(void) kstat_close(kc);
135}
136#else
137/* FreeBSD */
138static void
139fake_up_certain_popular_kernel_symbols(void)
140{
141	char *name;
142	uintptr_t addr;
143	int i;
144
145	/* Good for up to 256 CPUs */
146	for(i=0; i < 256;  i++) {
147		if ((name = malloc(20)) == NULL)
148			break;
149		(void) sprintf(name, "cpu[%d]", i);
150		addr = 0x01000000 + (i << 16);
151		add_symbol(name, addr, sizeof (uintptr_t));
152	}
153}
154#endif /* !defined(sun) */
155
156static int
157symcmp(const void *p1, const void *p2)
158{
159	uintptr_t a1 = ((syment_t *)p1)->addr;
160	uintptr_t a2 = ((syment_t *)p2)->addr;
161
162	if (a1 < a2)
163		return (-1);
164	if (a1 > a2)
165		return (1);
166	return (0);
167}
168
169int
170symtab_init(void)
171{
172	Elf		*elf;
173	Elf_Scn		*scn = NULL;
174	Sym		*symtab, *symp, *lastsym;
175	char		*strtab;
176	uint_t		cnt;
177	int		fd;
178	int		i;
179	int		strindex = -1;
180#if !defined(sun)
181	void		*ksyms;
182	size_t		sz;
183#endif
184
185#if defined(__FreeBSD__)
186	if ((fd = open("/dev/ksyms", O_RDONLY)) == -1) {
187		if (errno == ENOENT && modfind("ksyms") == -1) {
188			kldload("ksyms");
189			fd = open("/dev/ksyms", O_RDONLY);
190		}
191		if (fd == -1)
192			return (-1);
193	}
194#else
195	if ((fd = open("/dev/ksyms", O_RDONLY)) == -1)
196		return (-1);
197#endif
198
199#if defined(sun)
200	(void) elf_version(EV_CURRENT);
201
202	elf = elf_begin(fd, ELF_C_READ, NULL);
203#else
204	/* FreeBSD */
205	/*
206	 * XXX - libelf needs to be fixed so it will work with
207	 * non 'ordinary' files like /dev/ksyms.  The following
208	 * is a work around for now.
209	 */
210	if (elf_version(EV_CURRENT) == EV_NONE) {
211		close(fd);
212		return (-1);
213	}
214	if (ioctl(fd, KIOCGSIZE, &sz) < 0) {
215		close(fd);
216		return (-1);
217	}
218	if (ioctl(fd, KIOCGADDR, &ksyms) < 0) {
219		close(fd);
220		return (-1);
221	}
222	if ((elf = elf_memory(ksyms, sz)) == NULL) {
223		close(fd);
224		return (-1);
225	}
226#endif
227
228	for (cnt = 1; (scn = elf_nextscn(elf, scn)) != NULL; cnt++) {
229		Shdr *shdr = elf_getshdr(scn);
230		if (shdr->sh_type == SHT_SYMTAB) {
231			symtab = (Sym *)elf_getdata(scn, NULL)->d_buf;
232			nsyms = shdr->sh_size / shdr->sh_entsize;
233			strindex = shdr->sh_link;
234		}
235	}
236
237	for (cnt = 1; (scn = elf_nextscn(elf, scn)) != NULL; cnt++) {
238		if (cnt == strindex)
239			strtab = (char *)elf_getdata(scn, NULL)->d_buf;
240	}
241
242	lastsym = symtab + nsyms;
243	nsyms = 0;
244	for (symp = symtab; symp < lastsym; symp++)
245		if ((uint_t)ELF32_ST_TYPE(symp->st_info) <= STT_FUNC &&
246		    symp->st_size != 0)
247			add_symbol(symp->st_name + strtab,
248			    (uintptr_t)symp->st_value, (size_t)symp->st_size);
249
250	fake_up_certain_popular_kernel_symbols();
251	(void) sprintf(maxsymname, "0x%lx", ULONG_MAX);
252	add_symbol(maxsymname, ULONG_MAX, 1);
253
254	qsort(symbol_table, nsyms, sizeof (syment_t), symcmp);
255
256	/*
257	 * Destroy all duplicate symbols, then sort it again.
258	 */
259	for (i = 0; i < nsyms - 1; i++)
260		if (symbol_table[i].addr == symbol_table[i + 1].addr)
261			symbol_table[i].addr = 0;
262
263	qsort(symbol_table, nsyms, sizeof (syment_t), symcmp);
264
265	while (symbol_table[1].addr == 0) {
266		symbol_table++;
267		nsyms--;
268	}
269	symbol_table[0].name = "(usermode)";
270	symbol_table[0].addr = 0;
271	symbol_table[0].size = 1;
272
273	close(fd);
274	return (0);
275}
276
277char *
278addr_to_sym(uintptr_t addr, uintptr_t *offset, size_t *sizep)
279{
280	int lo = 0;
281	int hi = nsyms - 1;
282	int mid;
283	syment_t *sep;
284
285	while (hi - lo > 1) {
286		mid = (lo + hi) / 2;
287		if (addr >= symbol_table[mid].addr) {
288			lo = mid;
289		} else {
290			hi = mid;
291		}
292	}
293	sep = &symbol_table[lo];
294	*offset = addr - sep->addr;
295	*sizep = sep->size;
296	return (sep->name);
297}
298
299uintptr_t
300sym_to_addr(char *name)
301{
302	int i;
303	syment_t *sep = symbol_table;
304
305	for (i = 0; i < nsyms; i++) {
306		if (strcmp(name, sep->name) == 0)
307			return (sep->addr);
308		sep++;
309	}
310	return (0);
311}
312
313size_t
314sym_size(char *name)
315{
316	int i;
317	syment_t *sep = symbol_table;
318
319	for (i = 0; i < nsyms; i++) {
320		if (strcmp(name, sep->name) == 0)
321			return (sep->size);
322		sep++;
323	}
324	return (0);
325}
326