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) 1994, by Sun Microsytems, Inc.
24 */
25
26 #pragma ident "%Z%%M% %I% %E% SMI"
27
28 /*
29 * Interfaces for searching for elf specific information
30 */
31
32 #include <unistd.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <errno.h>
36 #include <link.h>
37 #include <sys/procfs.h>
38
39 #include "tnfctl_int.h"
40 #include "dbg.h"
41
42
43 /*
44 * Declarations
45 */
46
47 static tnfctl_errcode_t dynsec_num(tnfctl_handle_t *hndl, uintptr_t baseaddr,
48 int objfd, int *num_dyn);
49 static tnfctl_errcode_t elf_dynmatch(Elf *elf, char *strs, Elf_Scn *dyn_scn,
50 GElf_Shdr *dyn_shdr, Elf_Data *dyn_data,
51 uintptr_t baseaddr, tnfctl_elf_search_t * search_info_p);
52 static tnfctl_errcode_t dyn_findtag(
53 Elf3264_Dyn *start, /* start of dynam table read in */
54 Elf3264_Sword tag, /* tag to search for */
55 uintptr_t dynam_addr, /* address of _DYNAMIC in target */
56 int limit, /* number of entries in table */
57 uintptr_t *dentry_address); /* return value */
58
59
60 /* ---------------------------------------------------------------- */
61 /* ----------------------- Public Functions ----------------------- */
62 /* ---------------------------------------------------------------- */
63
64 /*
65 * _tnfctl_elf_dbgent() - this function finds the address of the
66 * debug struct (DT_DEBUG) in the target process. _DYNAMIC is a symbol
67 * present in every object. The one in the main executable references
68 * an array that is tagged with the kind of each member. We search
69 * for the tag of DT_DEBUG which is where the run time linker maintains
70 * a structure that references the shared object linked list.
71 *
72 * A side effect of searching for DT_DEBUG ensures that the executable is
73 * a dynamic executable - tracing only works on dynamic executables because
74 * static executables don't have relocation tables.
75 */
76 tnfctl_errcode_t
77 _tnfctl_elf_dbgent(tnfctl_handle_t *hndl, uintptr_t * entaddr_p)
78 {
79 tnfctl_errcode_t prexstat = TNFCTL_ERR_NONE;
80 prb_status_t prbstat = PRB_STATUS_OK;
81 int miscstat;
82 int objfd;
83 int num_dynentries = 0;
84 uintptr_t dynamic_addr;
85 uintptr_t baseaddr;
86 uintptr_t dentry_addr;
87 Elf3264_Dyn *dynam_tab = NULL;
88 long dynam_tab_size;
89
90 *entaddr_p = NULL;
91
92 prbstat = prb_mainobj_get(hndl->proc_p, &objfd, &baseaddr);
93 if (prbstat)
94 return (_tnfctl_map_to_errcode(prbstat));
95
96 /* find the address of the symbol _DYNAMIC */
97 prexstat = _tnfctl_sym_find_in_obj(objfd, baseaddr, "_DYNAMIC",
98 &dynamic_addr);
99 if (prexstat) {
100 prexstat = TNFCTL_ERR_NOTDYNAMIC;
101 goto Cleanup;
102 }
103
104 /* find the number of entries in the .dynamic section */
105 prexstat = dynsec_num(hndl, baseaddr, objfd, &num_dynentries);
106 if (prexstat)
107 goto Cleanup;
108
109 DBG_TNF_PROBE_2(_tnfctl_elf_dbgent_1, "libtnfctl", "sunw%verbosity 2",
110 tnf_long, num_of_dynentries, num_dynentries,
111 tnf_opaque, DYNAMIC_address, dynamic_addr);
112
113 /* read in the dynamic table from the image of the process */
114 dynam_tab_size = num_dynentries * sizeof (Elf3264_Dyn);
115 dynam_tab = malloc(dynam_tab_size);
116 if (!dynam_tab) {
117 close(objfd);
118 return (TNFCTL_ERR_ALLOCFAIL);
119 }
120 miscstat = hndl->p_read(hndl->proc_p, dynamic_addr, dynam_tab,
121 dynam_tab_size);
122 if (miscstat) {
123 prexstat = TNFCTL_ERR_INTERNAL;
124 goto Cleanup;
125 }
126
127 prexstat = dyn_findtag(dynam_tab, DT_DEBUG, dynamic_addr,
128 num_dynentries, &dentry_addr);
129 if (prexstat) {
130 goto Cleanup;
131 }
132 *entaddr_p = dentry_addr;
133
134 Cleanup:
135 close(objfd);
136 if (dynam_tab)
137 free(dynam_tab);
138 return (prexstat);
139
140 }
141
142
143 /* ---------------------------------------------------------------- */
144 /* ----------------------- Private Functions ---------------------- */
145 /* ---------------------------------------------------------------- */
146
147 /*
148 * dyn_findtag() - searches tags in _DYNAMIC table
149 */
150 static tnfctl_errcode_t
151 dyn_findtag(Elf3264_Dyn * start, /* start of dynam table read in */
152 Elf3264_Sword tag, /* tag to search for */
153 uintptr_t dynam_addr, /* base address of _DYNAMIC in target */
154 int limit, /* number of entries in table */
155 uintptr_t * dentry_address)
156 { /* return value */
157 Elf3264_Dyn *dp;
158
159 for (dp = start; dp->d_tag != DT_NULL; dp++) {
160
161 DBG_TNF_PROBE_1(dyn_findtag_1, "libtnfctl",
162 "sunw%verbosity 3; sunw%debug 'in loop'",
163 tnf_long, tag, dp->d_tag);
164
165 if (dp->d_tag == tag) {
166 *dentry_address = dynam_addr +
167 (dp - start) * sizeof (Elf3264_Dyn);
168 return (TNFCTL_ERR_NONE);
169 }
170 if (--limit <= 0) {
171 DBG((void) fprintf(stderr,
172 "dyn_findtag: exceeded limit of table\n"));
173 return (TNFCTL_ERR_INTERNAL);
174 }
175 }
176
177 DBG((void) fprintf(stderr,
178 "dyn_findtag: couldn't find tag, last tag=%d\n",
179 (int) dp->d_tag));
180 return (TNFCTL_ERR_INTERNAL);
181 }
182
183
184 /*
185 * dynsec_num() - find the number of entries in the .dynamic section
186 */
187 /*ARGSUSED*/
188 static tnfctl_errcode_t
189 dynsec_num(tnfctl_handle_t *hndl, uintptr_t baseaddr,
190 int objfd, int *num_dyn)
191 {
192 int num_ent = 0;
193 tnfctl_errcode_t prexstat;
194 tnfctl_elf_search_t search_info;
195
196 DBG_TNF_PROBE_0(dynsec_num_1, "libtnfctl",
197 "sunw%verbosity 2;"
198 "sunw%debug 'counting number of entries in .dynamic section'");
199
200 search_info.section_func = elf_dynmatch;
201 search_info.section_data = &num_ent;
202
203 prexstat = _tnfctl_traverse_object(objfd, baseaddr, &search_info);
204 if (prexstat)
205 return (prexstat);
206
207 if (num_ent == 0)
208 return (TNFCTL_ERR_NOTDYNAMIC);
209
210 *num_dyn = num_ent;
211
212 return (TNFCTL_ERR_NONE);
213 }
214
215
216 /*
217 * elf_dynmatch() - this function searches for the .dynamic section and
218 * returns the number of entries in it.
219 */
220 /*ARGSUSED*/
221 static tnfctl_errcode_t
222 elf_dynmatch(Elf * elf,
223 char *strs,
224 Elf_Scn * dyn_scn,
225 GElf_Shdr * dyn_shdr,
226 Elf_Data * dyn_data,
227 uintptr_t baseaddr,
228 tnfctl_elf_search_t *search_info_p)
229 {
230 char *scn_name;
231 int *ret = (int *) search_info_p->section_data;
232
233 /* bail if this isn't a .dynamic section */
234 scn_name = strs + dyn_shdr->sh_name;
235 if (strcmp(scn_name, ".dynamic") != 0)
236 return (TNFCTL_ERR_NONE);
237
238 if (dyn_shdr->sh_entsize == 0) { /* no dynamic section */
239 *ret = 0;
240 } else {
241 *ret = (int) (dyn_shdr->sh_size / dyn_shdr->sh_entsize);
242 }
243 return (TNFCTL_ERR_NONE);
244 }