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 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 
30 #include	<libelf.h>
31 #include	<sys/regset.h>
32 #include	<rtld_db.h>
33 #include	<_rtld_db.h>
34 #include	<msg.h>
35 #include	<stdio.h>
36 
37 
38 typedef	struct {
39     rd_agent_t	*rlid_rap;
40     psaddr_t	rlid_pltaddr;
41     psaddr_t	rlid_gotaddr;
42     rd_err_e	rlid_ret;
43 } Rli_data;
44 
45 /*
46  * Iterator function for rd_loadobj_iter - we are scaning
47  * each object loaded to try and find the object defining
48  * the current PLT being traversed - when found we return
49  * the GOT pointer for that object.
50  */
51 static int
rli_func(const rd_loadobj_t * rl,void * data)52 rli_func(const rd_loadobj_t *rl, void *data)
53 {
54 	Ehdr	    ehdr;
55 	Phdr	    phdr;
56 	Rli_data    *rli_data;
57 	ulong_t	    off;
58 	psaddr_t    baseaddr;
59 	psaddr_t    pltaddr;
60 	uint_t	    i;
61 	uint_t	    found_obj = 0;
62 	psaddr_t    dynbase = 0;
63 	rd_agent_t  *rap;
64 	rd_err_e    rc;
65 
66 	rli_data = (Rli_data *)data;
67 	pltaddr = rli_data->rlid_pltaddr;
68 	rap = rli_data->rlid_rap;
69 
70 	if (ps_pread(rap->rd_psp, rl->rl_base, (char *)&ehdr,
71 	    sizeof (Ehdr)) != PS_OK) {
72 		rli_data->rlid_ret = RD_ERR;
73 		LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_X86_1),
74 		    EC_ADDR(rl->rl_base)));
75 		return (0);
76 	}
77 	if (ehdr.e_type == ET_EXEC)
78 	    baseaddr = 0;
79 	else
80 	    baseaddr = rl->rl_base;
81 
82 	off = rl->rl_base + ehdr.e_phoff;
83 	for (i = 0; i < ehdr.e_phnum; i++) {
84 		if (ps_pread(rap->rd_psp, off, (char *)&phdr,
85 		    sizeof (Phdr)) != PS_OK) {
86 			rli_data->rlid_ret = RD_ERR;
87 			LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_X86_1),
88 			    EC_ADDR(rl->rl_base)));
89 			return (0);
90 		}
91 		if (phdr.p_type == PT_LOAD) {
92 			if ((pltaddr >= (phdr.p_vaddr + baseaddr)) &&
93 			    (pltaddr < (phdr.p_vaddr + baseaddr +
94 			    phdr.p_memsz))) {
95 				found_obj = 1;
96 			}
97 		} else if (phdr.p_type == PT_DYNAMIC)  {
98 			dynbase = phdr.p_vaddr + baseaddr;
99 		}
100 		off += ehdr.e_phentsize;
101 
102 		if (found_obj & dynbase)
103 			break;
104 	}
105 
106 	if (found_obj) {
107 		Dyn dynent;
108 
109 		if (dynbase == 0) {
110 			LOG(ps_plog(MSG_ORIG(MSG_DB_NODYN_X86)));
111 			rli_data->rlid_ret = RD_ERR;
112 			return (0);
113 		}
114 		if ((rc = find_dynamic_ent32(rap, dynbase, DT_PLTGOT,
115 		    &dynent)) != RD_OK) {
116 			rli_data->rlid_ret = rc;
117 			return (0);
118 		}
119 		/*
120 		 * We've found our gotpntr. Return (0) to stop
121 		 * the 'iteration'.
122 		 */
123 		rli_data->rlid_gotaddr = dynent.d_un.d_val + baseaddr;
124 		return (0);
125 	}
126 
127 	return (1);
128 }
129 
130 
131 /*
132  * On x86, basically, a PLT entry looks like this:
133  *	8048738:  ff 25 c8 45 05 08   jmp    *0x80545c8	 < OFFSET_INTO_GOT>
134  *	804873e:  68 20 00 00 00      pushl  $0x20
135  *	8048743:  e9 70 ff ff ff      jmp    0xffffff70 <80486b8> < &.plt >
136  *
137  *  The first time around OFFSET_INTO_GOT contains address of pushl; this forces
138  *	first time resolution to go thru PLT's first entry (which is a call)
139  *  The nth time around, the OFFSET_INTO_GOT actually contains the resolved
140  *	address of the symbol(name), so the jmp is direct  [VT]
141  *  The only complication is when going from a .so to an a.out or to another
142  *	.so, we must resolve where the GOT table is for the given object.
143  */
144 /* ARGSUSED 3 */
145 rd_err_e
plt32_resolution(rd_agent_t * rap,psaddr_t pc,lwpid_t lwpid,psaddr_t pltbase,rd_plt_info_t * rpi)146 plt32_resolution(rd_agent_t *rap, psaddr_t pc, lwpid_t lwpid,
147 	psaddr_t pltbase, rd_plt_info_t *rpi)
148 {
149 	unsigned	addr;
150 	unsigned	ebx;
151 	psaddr_t	pltoff, pltaddr;
152 
153 
154 	if (rtld_db_version >= RD_VERSION3) {
155 		rpi->pi_flags = 0;
156 		rpi->pi_baddr = 0;
157 	}
158 
159 	pltoff = pc - pltbase;
160 	pltaddr = pltbase +
161 		((pltoff / M_PLT_ENTSIZE) * M_PLT_ENTSIZE);
162 	/*
163 	 * This is the target of the jmp instruction
164 	 */
165 	if (ps_pread(rap->rd_psp, pltaddr + 2, (char *)&addr,
166 	    sizeof (unsigned)) != PS_OK) {
167 		LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(pltaddr + 2)));
168 		return (RD_ERR);
169 	}
170 
171 	/*
172 	 * Is this branch %ebx relative
173 	 */
174 	if (ps_pread(rap->rd_psp, pltaddr + 1, (char *)&ebx,
175 	    sizeof (unsigned)) != PS_OK) {
176 		LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(pltaddr + 1)));
177 		return (RD_ERR);
178 	}
179 
180 	/*
181 	 * If this .plt call is made via a GOT table (pic code), then
182 	 * in order to resolve the PLT we must determine where the
183 	 * GOT table is for the object making the call.
184 	 *
185 	 * We do this by using the rd_loadobj_iter() logic to scan
186 	 * all of the objects currently loaded into memory, when we
187 	 * find one which contains the .PLT table in question - we
188 	 * find the GOT address for that object.
189 	 */
190 	if ((ebx & 0xff) == 0xa3) {
191 		rd_err_e    rderr;
192 		Rli_data    rli_data;
193 
194 		rli_data.rlid_ret = RD_OK;
195 		rli_data.rlid_pltaddr = pltaddr;
196 		rli_data.rlid_rap = rap;
197 		rli_data.rlid_gotaddr = 0;
198 		if ((rderr = _rd_loadobj_iter32(rap, rli_func, &rli_data))
199 		    != RD_OK) {
200 			return (rderr);
201 		}
202 
203 		if (rli_data.rlid_ret != RD_OK) {
204 			return (rli_data.rlid_ret);
205 		}
206 
207 		if (rli_data.rlid_gotaddr == 0) {
208 			LOG(ps_plog(MSG_ORIG(MSG_DB_NOGOT_X86)));
209 			return (RD_ERR);
210 		}
211 		addr += rli_data.rlid_gotaddr;
212 	}
213 
214 	/*
215 	 * Find out what's pointed to by @OFFSET_INTO_GOT
216 	 */
217 	if (ps_pread(rap->rd_psp, addr, (char *)&addr,
218 	    sizeof (unsigned)) != PS_OK) {
219 		LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(addr)));
220 		return (RD_ERR);
221 	}
222 	if (addr == (pltaddr + 6)) {
223 		rd_err_e	rerr;
224 		/*
225 		 * If GOT[ind] points to PLT+6 then this is the first
226 		 * time through this PLT.
227 		 */
228 		if ((rerr = rd_binder_exit_addr(rap, MSG_ORIG(MSG_SYM_RTBIND),
229 		    &(rpi->pi_target))) != RD_OK) {
230 			return (rerr);
231 		}
232 		rpi->pi_skip_method = RD_RESOLVE_TARGET_STEP;
233 		rpi->pi_nstep = 1;
234 	} else {
235 		/*
236 		 * This is the n'th time through and GOT[ind] points
237 		 * to the final destination.
238 		 */
239 		rpi->pi_skip_method = RD_RESOLVE_STEP;
240 		rpi->pi_nstep = 1;
241 		rpi->pi_target = 0;
242 		if (rtld_db_version >= RD_VERSION3) {
243 			rpi->pi_flags |= RD_FLG_PI_PLTBOUND;
244 			rpi->pi_baddr = addr;
245 		}
246 	}
247 
248 	return (RD_OK);
249 }
250