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 (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * x86 relocation code.
29 */
30
31 #include <sys/types.h>
32 #include <sys/param.h>
33 #include <sys/sysmacros.h>
34 #include <sys/systm.h>
35 #include <sys/user.h>
36 #include <sys/bootconf.h>
37 #include <sys/modctl.h>
38 #include <sys/elf.h>
39 #include <sys/kobj.h>
40 #include <sys/kobj_impl.h>
41 #include <sys/tnf.h>
42 #include <sys/tnf_probe.h>
43
44 #include "reloc.h"
45
46
47 /*
48 * Probe Discovery
49 */
50
51 #define PROBE_MARKER_SYMBOL "__tnf_probe_version_1"
52 #define TAG_MARKER_SYMBOL "__tnf_tag_version_1"
53
54 extern int tnf_splice_probes(int, tnf_probe_control_t *, tnf_tag_data_t *);
55
56 /*
57 * The kernel run-time linker calls this to try to resolve a reference
58 * it can't otherwise resolve. We see if it's marking a probe control
59 * block; if so, we do the resolution and return 0. If not, we return
60 * 1 to show that we can't resolve it, either.
61 */
62 static int
63 tnf_reloc_resolve(char *symname, Addr *value_p,
64 Elf64_Sxword *addend_p,
65 long offset,
66 tnf_probe_control_t **probelist,
67 tnf_tag_data_t **taglist)
68 {
69 if (strcmp(symname, PROBE_MARKER_SYMBOL) == 0) {
70 *addend_p = 0;
71 ((tnf_probe_control_t *)offset)->next = *probelist;
72 *probelist = (tnf_probe_control_t *)offset;
73 return (0);
74 }
75 if (strcmp(symname, TAG_MARKER_SYMBOL) == 0) {
76 *addend_p = 0;
77 *value_p = (Addr)*taglist;
78 *taglist = (tnf_tag_data_t *)offset;
79 return (0);
80 }
81 return (1);
82 }
83
84 #define SDT_NOP 0x90
85 #define SDT_NOPS 5
86
87 static int
88 sdt_reloc_resolve(struct module *mp, char *symname, uint8_t *instr)
89 {
90 sdt_probedesc_t *sdp;
91 int i;
92
93 /*
94 * The "statically defined tracing" (SDT) provider for DTrace uses
95 * a mechanism similar to TNF, but somewhat simpler. (Surprise,
96 * surprise.) The SDT mechanism works by replacing calls to the
97 * undefined routine __dtrace_probe_[name] with nop instructions.
98 * The relocations are logged, and SDT itself will later patch the
99 * running binary appropriately.
100 */
101 if (strncmp(symname, sdt_prefix, strlen(sdt_prefix)) != 0)
102 return (1);
103
104 symname += strlen(sdt_prefix);
105
106 sdp = kobj_alloc(sizeof (sdt_probedesc_t), KM_WAIT);
107 sdp->sdpd_name = kobj_alloc(strlen(symname) + 1, KM_WAIT);
108 bcopy(symname, sdp->sdpd_name, strlen(symname) + 1);
109
110 sdp->sdpd_offset = (uintptr_t)instr;
111 sdp->sdpd_next = mp->sdt_probes;
112 mp->sdt_probes = sdp;
113
114 for (i = 0; i < SDT_NOPS; i++)
115 instr[i - 1] = SDT_NOP;
116
117 return (0);
118 }
119
120 int
121 do_relocate(struct module *mp, char *reltbl, int nreloc, int relocsize,
122 Addr baseaddr)
123 {
124 unsigned long stndx;
125 unsigned long off; /* can't be register for tnf_reloc_resolve() */
126 register unsigned long reladdr, rend;
127 register unsigned int rtype;
128 unsigned long value;
129 Elf64_Sxword addend;
130 Sym *symref = NULL;
131 int err = 0;
132 tnf_probe_control_t *probelist = NULL;
133 tnf_tag_data_t *taglist = NULL;
134 int symnum;
135 reladdr = (unsigned long)reltbl;
136 rend = reladdr + nreloc * relocsize;
137
138 #ifdef KOBJ_DEBUG
139 if (kobj_debug & D_RELOCATIONS) {
140 _kobj_printf(ops, "krtld:\ttype\t\t\toffset\t addend"
141 " symbol\n");
142 _kobj_printf(ops, "krtld:\t\t\t\t\t value\n");
143 }
144 #endif
145
146 symnum = -1;
147 /* loop through relocations */
148 while (reladdr < rend) {
149 symnum++;
150 rtype = ELF_R_TYPE(((Rela *)reladdr)->r_info);
151 off = ((Rela *)reladdr)->r_offset;
152 stndx = ELF_R_SYM(((Rela *)reladdr)->r_info);
153 if (stndx >= mp->nsyms) {
154 _kobj_printf(ops, "do_relocate: bad strndx %d\n",
155 symnum);
156 return (-1);
157 }
158 if ((rtype > R_AMD64_NUM) || IS_TLS_INS(rtype)) {
159 _kobj_printf(ops, "krtld: invalid relocation type %d",
160 rtype);
161 _kobj_printf(ops, " at 0x%llx:", off);
162 _kobj_printf(ops, " file=%s\n", mp->filename);
163 err = 1;
164 continue;
165 }
166
167
168 addend = (long)(((Rela *)reladdr)->r_addend);
169 reladdr += relocsize;
170
171
172 if (rtype == R_AMD64_NONE)
173 continue;
174
175 #ifdef KOBJ_DEBUG
176 if (kobj_debug & D_RELOCATIONS) {
177 Sym * symp;
178 symp = (Sym *)
179 (mp->symtbl+(stndx * mp->symhdr->sh_entsize));
180 _kobj_printf(ops, "krtld:\t%s",
181 conv_reloc_amd64_type(rtype));
182 _kobj_printf(ops, "\t0x%8llx", off);
183 _kobj_printf(ops, " 0x%8llx", addend);
184 _kobj_printf(ops, " %s\n",
185 (const char *)mp->strings + symp->st_name);
186 }
187 #endif
188
189 if (!(mp->flags & KOBJ_EXEC))
190 off += baseaddr;
191
192 /*
193 * if R_AMD64_RELATIVE, simply add base addr
194 * to reloc location
195 */
196
197 if (rtype == R_AMD64_RELATIVE) {
198 value = baseaddr;
199 } else {
200 /*
201 * get symbol table entry - if symbol is local
202 * value is base address of this object
203 */
204 symref = (Sym *)
205 (mp->symtbl+(stndx * mp->symhdr->sh_entsize));
206
207 if (ELF_ST_BIND(symref->st_info) == STB_LOCAL) {
208 /* *** this is different for .o and .so */
209 value = symref->st_value;
210 } else {
211 /*
212 * It's global. Allow weak references. If
213 * the symbol is undefined, give TNF (the
214 * kernel probes facility) a chance to see
215 * if it's a probe site, and fix it up if so.
216 */
217 if (symref->st_shndx == SHN_UNDEF &&
218 sdt_reloc_resolve(mp, mp->strings +
219 symref->st_name, (uint8_t *)off) == 0)
220 continue;
221
222 if (symref->st_shndx == SHN_UNDEF &&
223 tnf_reloc_resolve(mp->strings +
224 symref->st_name, &symref->st_value,
225 &addend, off, &probelist, &taglist) != 0) {
226 if (ELF_ST_BIND(symref->st_info)
227 != STB_WEAK) {
228 _kobj_printf(ops,
229 "not found: %s\n",
230 mp->strings +
231 symref->st_name);
232 err = 1;
233 }
234 continue;
235 } else { /* symbol found - relocate */
236 /*
237 * calculate location of definition
238 * - symbol value plus base address of
239 * containing shared object
240 */
241 value = symref->st_value;
242
243 } /* end else symbol found */
244 } /* end global or weak */
245 } /* end not R_AMD64_RELATIVE */
246
247 value += addend;
248 /*
249 * calculate final value -
250 * if PC-relative, subtract ref addr
251 */
252 if (IS_PC_RELATIVE(rtype))
253 value -= off;
254
255 #ifdef KOBJ_DEBUG
256 if (kobj_debug & D_RELOCATIONS) {
257 _kobj_printf(ops, "krtld:\t\t\t\t0x%8llx", off);
258 _kobj_printf(ops, " 0x%8llx\n", value);
259 }
260 #endif
261
262 if (do_reloc_krtld(rtype, (unsigned char *)off, &value,
263 (const char *)mp->strings + symref->st_name,
264 mp->filename) == 0)
265 err = 1;
266
267 } /* end of while loop */
268 if (err)
269 return (-1);
270
271 if (tnf_splice_probes(mp->flags & KOBJ_PRIM, probelist, taglist))
272 mp->flags |= KOBJ_TNF_PROBE;
273
274 return (0);
275 }
276
277 int
278 do_relocations(struct module *mp)
279 {
280 uint_t shn;
281 Shdr *shp, *rshp;
282 uint_t nreloc;
283
284 /* do the relocations */
285 for (shn = 1; shn < mp->hdr.e_shnum; shn++) {
286 rshp = (Shdr *)
287 (mp->shdrs + shn * mp->hdr.e_shentsize);
288 if (rshp->sh_type == SHT_REL) {
289 _kobj_printf(ops, "%s can't process type SHT_REL\n",
290 mp->filename);
291 return (-1);
292 }
293 if (rshp->sh_type != SHT_RELA)
294 continue;
295 if (rshp->sh_link != mp->symtbl_section) {
296 _kobj_printf(ops, "%s reloc for non-default symtab\n",
297 mp->filename);
298 return (-1);
299 }
300 if (rshp->sh_info >= mp->hdr.e_shnum) {
301 _kobj_printf(ops, "do_relocations: %s sh_info ",
302 mp->filename);
303 _kobj_printf(ops, "out of range %d\n", shn);
304 goto bad;
305 }
306 nreloc = rshp->sh_size / rshp->sh_entsize;
307
308 /* get the section header that this reloc table refers to */
309 shp = (Shdr *)
310 (mp->shdrs + rshp->sh_info * mp->hdr.e_shentsize);
311
312 /*
313 * Do not relocate any section that isn't loaded into memory.
314 * Most commonly this will skip over the .rela.stab* sections
315 */
316 if (!(shp->sh_flags & SHF_ALLOC))
317 continue;
318 #ifdef KOBJ_DEBUG
319 if (kobj_debug & D_RELOCATIONS) {
320 _kobj_printf(ops, "krtld: relocating: file=%s ",
321 mp->filename);
322 _kobj_printf(ops, "section=%d\n", shn);
323 }
324 #endif
325
326 if (do_relocate(mp, (char *)rshp->sh_addr, nreloc,
327 rshp->sh_entsize, shp->sh_addr) < 0) {
328 _kobj_printf(ops,
329 "do_relocations: %s do_relocate failed\n",
330 mp->filename);
331 goto bad;
332 }
333 kobj_free((void *)rshp->sh_addr, rshp->sh_size);
334 rshp->sh_addr = 0;
335 }
336 mp->flags |= KOBJ_RELOCATED;
337 return (0);
338 bad:
339 kobj_free((void *)rshp->sh_addr, rshp->sh_size);
340 rshp->sh_addr = 0;
341 return (-1);
342 }