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 2004 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #include <libelf.h>
28 #include <sys/regset.h>
29 #include <rtld_db.h>
30 #include <_rtld_db.h>
31 #include <msg.h>
32 #include <stdio.h>
33
34
35 typedef struct {
36 rd_agent_t *rlid_rap;
37 psaddr_t rlid_pltaddr;
38 psaddr_t rlid_gotaddr;
39 rd_err_e rlid_ret;
40 } Rli_data;
41
42 /*
43 * Iterator function for rd_loadobj_iter - we are scaning
44 * each object loaded to try and find the object defining
45 * the current PLT being traversed - when found we return
46 * the GOT pointer for that object.
47 */
48 static int
rli_func(const rd_loadobj_t * rl,void * data)49 rli_func(const rd_loadobj_t *rl, void *data)
50 {
51 Ehdr ehdr;
52 Phdr phdr;
53 Rli_data *rli_data;
54 ulong_t off;
55 psaddr_t baseaddr;
56 psaddr_t pltaddr;
57 uint_t i;
58 uint_t found_obj = 0;
59 psaddr_t dynbase = 0;
60 rd_agent_t *rap;
61 rd_err_e rc;
62
63 rli_data = (Rli_data *)data;
64 pltaddr = rli_data->rlid_pltaddr;
65 rap = rli_data->rlid_rap;
66
67 if (ps_pread(rap->rd_psp, rl->rl_base, (char *)&ehdr,
68 sizeof (Ehdr)) != PS_OK) {
69 rli_data->rlid_ret = RD_ERR;
70 LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_X86_1),
71 EC_ADDR(rl->rl_base)));
72 return (0);
73 }
74 if (ehdr.e_type == ET_EXEC)
75 baseaddr = 0;
76 else
77 baseaddr = rl->rl_base;
78
79 off = rl->rl_base + ehdr.e_phoff;
80 for (i = 0; i < ehdr.e_phnum; i++) {
81 if (ps_pread(rap->rd_psp, off, (char *)&phdr,
82 sizeof (Phdr)) != PS_OK) {
83 rli_data->rlid_ret = RD_ERR;
84 LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_X86_1),
85 EC_ADDR(rl->rl_base)));
86 return (0);
87 }
88 if (phdr.p_type == PT_LOAD) {
89 if ((pltaddr >= (phdr.p_vaddr + baseaddr)) &&
90 (pltaddr < (phdr.p_vaddr + baseaddr +
91 phdr.p_memsz))) {
92 found_obj = 1;
93 }
94 } else if (phdr.p_type == PT_DYNAMIC) {
95 dynbase = phdr.p_vaddr + baseaddr;
96 }
97 off += ehdr.e_phentsize;
98
99 if (found_obj & dynbase)
100 break;
101 }
102
103 if (found_obj) {
104 Dyn dynent;
105
106 if (dynbase == 0) {
107 LOG(ps_plog(MSG_ORIG(MSG_DB_NODYN_X86)));
108 rli_data->rlid_ret = RD_ERR;
109 return (0);
110 }
111 if ((rc = find_dynamic_ent32(rap, dynbase, DT_PLTGOT,
112 &dynent)) != RD_OK) {
113 rli_data->rlid_ret = rc;
114 return (0);
115 }
116 /*
117 * We've found our gotpntr. Return (0) to stop
118 * the 'iteration'.
119 */
120 rli_data->rlid_gotaddr = dynent.d_un.d_val + baseaddr;
121 return (0);
122 }
123
124 return (1);
125 }
126
127
128 /*
129 * On x86, basically, a PLT entry looks like this:
130 * 8048738: ff 25 c8 45 05 08 jmp *0x80545c8 < OFFSET_INTO_GOT>
131 * 804873e: 68 20 00 00 00 pushl $0x20
132 * 8048743: e9 70 ff ff ff jmp 0xffffff70 <80486b8> < &.plt >
133 *
134 * The first time around OFFSET_INTO_GOT contains address of pushl; this forces
135 * first time resolution to go thru PLT's first entry (which is a call)
136 * The nth time around, the OFFSET_INTO_GOT actually contains the resolved
137 * address of the symbol(name), so the jmp is direct [VT]
138 * The only complication is when going from a .so to an executable or to
139 * another .so, we must resolve where the GOT table is for the given
140 * object.
141 */
142 /* ARGSUSED 3 */
143 rd_err_e
plt32_resolution(rd_agent_t * rap,psaddr_t pc,lwpid_t lwpid,psaddr_t pltbase,rd_plt_info_t * rpi)144 plt32_resolution(rd_agent_t *rap, psaddr_t pc, lwpid_t lwpid,
145 psaddr_t pltbase, rd_plt_info_t *rpi)
146 {
147 unsigned addr;
148 unsigned ebx;
149 psaddr_t pltoff, pltaddr;
150
151
152 if (rtld_db_version >= RD_VERSION3) {
153 rpi->pi_flags = 0;
154 rpi->pi_baddr = 0;
155 }
156
157 pltoff = pc - pltbase;
158 pltaddr = pltbase +
159 ((pltoff / M_PLT_ENTSIZE) * M_PLT_ENTSIZE);
160 /*
161 * This is the target of the jmp instruction
162 */
163 if (ps_pread(rap->rd_psp, pltaddr + 2, (char *)&addr,
164 sizeof (unsigned)) != PS_OK) {
165 LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(pltaddr + 2)));
166 return (RD_ERR);
167 }
168
169 /*
170 * Is this branch %ebx relative
171 */
172 if (ps_pread(rap->rd_psp, pltaddr + 1, (char *)&ebx,
173 sizeof (unsigned)) != PS_OK) {
174 LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(pltaddr + 1)));
175 return (RD_ERR);
176 }
177
178 /*
179 * If this .plt call is made via a GOT table (pic code), then
180 * in order to resolve the PLT we must determine where the
181 * GOT table is for the object making the call.
182 *
183 * We do this by using the rd_loadobj_iter() logic to scan
184 * all of the objects currently loaded into memory, when we
185 * find one which contains the .PLT table in question - we
186 * find the GOT address for that object.
187 */
188 if ((ebx & 0xff) == 0xa3) {
189 rd_err_e rderr;
190 Rli_data rli_data;
191
192 rli_data.rlid_ret = RD_OK;
193 rli_data.rlid_pltaddr = pltaddr;
194 rli_data.rlid_rap = rap;
195 rli_data.rlid_gotaddr = 0;
196 if ((rderr = _rd_loadobj_iter32(rap, rli_func, &rli_data))
197 != RD_OK) {
198 return (rderr);
199 }
200
201 if (rli_data.rlid_ret != RD_OK) {
202 return (rli_data.rlid_ret);
203 }
204
205 if (rli_data.rlid_gotaddr == 0) {
206 LOG(ps_plog(MSG_ORIG(MSG_DB_NOGOT_X86)));
207 return (RD_ERR);
208 }
209 addr += rli_data.rlid_gotaddr;
210 }
211
212 /*
213 * Find out what's pointed to by @OFFSET_INTO_GOT
214 */
215 if (ps_pread(rap->rd_psp, addr, (char *)&addr,
216 sizeof (unsigned)) != PS_OK) {
217 LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(addr)));
218 return (RD_ERR);
219 }
220 if (addr == (pltaddr + 6)) {
221 rd_err_e rerr;
222 /*
223 * If GOT[ind] points to PLT+6 then this is the first
224 * time through this PLT.
225 */
226 if ((rerr = rd_binder_exit_addr(rap, MSG_ORIG(MSG_SYM_RTBIND),
227 &(rpi->pi_target))) != RD_OK) {
228 return (rerr);
229 }
230 rpi->pi_skip_method = RD_RESOLVE_TARGET_STEP;
231 rpi->pi_nstep = 1;
232 } else {
233 /*
234 * This is the n'th time through and GOT[ind] points
235 * to the final destination.
236 */
237 rpi->pi_skip_method = RD_RESOLVE_STEP;
238 rpi->pi_nstep = 1;
239 rpi->pi_target = 0;
240 if (rtld_db_version >= RD_VERSION3) {
241 rpi->pi_flags |= RD_FLG_PI_PLTBOUND;
242 rpi->pi_baddr = addr;
243 }
244 }
245
246 return (RD_OK);
247 }
248