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 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 /*
30 * x86 relocation code.
31 */
32
33 #include <sys/types.h>
34 #include <sys/param.h>
35 #include <sys/sysmacros.h>
36 #include <sys/systm.h>
37 #include <sys/user.h>
38 #include <sys/bootconf.h>
39 #include <sys/modctl.h>
40 #include <sys/elf.h>
41 #include <sys/kobj.h>
42 #include <sys/kobj_impl.h>
43 #include <sys/tnf.h>
44 #include <sys/tnf_probe.h>
45
46 #include "reloc.h"
47
48
49 /*
50 * Probe Discovery
51 */
52
53 #define PROBE_MARKER_SYMBOL "__tnf_probe_version_1"
54 #define TAG_MARKER_SYMBOL "__tnf_tag_version_1"
55
56 extern int tnf_splice_probes(int, tnf_probe_control_t *, tnf_tag_data_t *);
57
58 /*
59 * The kernel run-time linker calls this to try to resolve a reference
60 * it can't otherwise resolve. We see if it's marking a probe control
61 * block; if so, we do the resolution and return 0. If not, we return
62 * 1 to show that we can't resolve it, either.
63 */
64 static int
65 tnf_reloc_resolve(char *symname, Addr *value_p,
66 Elf64_Sxword *addend_p,
67 long offset,
68 tnf_probe_control_t **probelist,
69 tnf_tag_data_t **taglist)
70 {
71 if (strcmp(symname, PROBE_MARKER_SYMBOL) == 0) {
72 *addend_p = 0;
73 ((tnf_probe_control_t *)offset)->next = *probelist;
74 *probelist = (tnf_probe_control_t *)offset;
75 return (0);
76 }
77 if (strcmp(symname, TAG_MARKER_SYMBOL) == 0) {
78 *addend_p = 0;
79 *value_p = (Addr)*taglist;
80 *taglist = (tnf_tag_data_t *)offset;
81 return (0);
82 }
83 return (1);
84 }
85
86 #define SDT_NOP 0x90
87 #define SDT_NOPS 5
88
89 static int
90 sdt_reloc_resolve(struct module *mp, char *symname, uint8_t *instr)
91 {
92 sdt_probedesc_t *sdp;
93 int i;
94
95 /*
96 * The "statically defined tracing" (SDT) provider for DTrace uses
97 * a mechanism similar to TNF, but somewhat simpler. (Surprise,
98 * surprise.) The SDT mechanism works by replacing calls to the
99 * undefined routine __dtrace_probe_[name] with nop instructions.
100 * The relocations are logged, and SDT itself will later patch the
101 * running binary appropriately.
102 */
103 if (strncmp(symname, sdt_prefix, strlen(sdt_prefix)) != 0)
104 return (1);
105
106 symname += strlen(sdt_prefix);
107
108 sdp = kobj_alloc(sizeof (sdt_probedesc_t), KM_WAIT);
109 sdp->sdpd_name = kobj_alloc(strlen(symname) + 1, KM_WAIT);
110 bcopy(symname, sdp->sdpd_name, strlen(symname) + 1);
111
112 sdp->sdpd_offset = (uintptr_t)instr;
113 sdp->sdpd_next = mp->sdt_probes;
114 mp->sdt_probes = sdp;
115
116 for (i = 0; i < SDT_NOPS; i++)
117 instr[i - 1] = SDT_NOP;
118
119 return (0);
120 }
121
122 int
123 /* ARGSUSED2 */
124 do_relocate(struct module *mp, char *reltbl, Word relshtype, int nreloc,
125 int relocsize, Addr baseaddr)
126 {
127 unsigned long stndx;
128 unsigned long off; /* can't be register for tnf_reloc_resolve() */
129 register unsigned long reladdr, rend;
130 register unsigned int rtype;
131 unsigned long value;
132 Elf64_Sxword addend;
133 Sym *symref;
134 int err = 0;
135 tnf_probe_control_t *probelist = NULL;
136 tnf_tag_data_t *taglist = NULL;
137 int symnum;
138 reladdr = (unsigned long)reltbl;
139 rend = reladdr + nreloc * relocsize;
140
141 #ifdef KOBJ_DEBUG
142 if (kobj_debug & D_RELOCATIONS) {
143 _kobj_printf(ops, "krtld:\ttype\t\t\toffset\t addend"
144 " symbol\n");
145 _kobj_printf(ops, "krtld:\t\t\t\t\t value\n");
146 }
147 #endif
148
149 symnum = -1;
150 /* loop through relocations */
151 while (reladdr < rend) {
152 symnum++;
153 rtype = ELF_R_TYPE(((Rela *)reladdr)->r_info);
154 off = ((Rela *)reladdr)->r_offset;
155 stndx = ELF_R_SYM(((Rela *)reladdr)->r_info);
156 if (stndx >= mp->nsyms) {
157 _kobj_printf(ops, "do_relocate: bad strndx %d\n",
158 symnum);
159 return (-1);
160 }
161 if ((rtype > R_AMD64_NUM) || IS_TLS_INS(rtype)) {
162 _kobj_printf(ops, "krtld: invalid relocation type %d",
163 rtype);
164 _kobj_printf(ops, " at 0x%llx:", off);
165 _kobj_printf(ops, " file=%s\n", mp->filename);
166 err = 1;
167 continue;
168 }
169
170
171 addend = (long)(((Rela *)reladdr)->r_addend);
172 reladdr += relocsize;
173
174
175 if (rtype == R_AMD64_NONE)
176 continue;
177
178 #ifdef KOBJ_DEBUG
179 if (kobj_debug & D_RELOCATIONS) {
180 Sym * symp;
181 symp = (Sym *)
182 (mp->symtbl+(stndx * mp->symhdr->sh_entsize));
183 _kobj_printf(ops, "krtld:\t%s",
184 conv_reloc_amd64_type(rtype));
185 _kobj_printf(ops, "\t0x%8llx", off);
186 _kobj_printf(ops, " 0x%8llx", addend);
187 _kobj_printf(ops, " %s\n",
188 (const char *)mp->strings + symp->st_name);
189 }
190 #endif
191
192 if (!(mp->flags & KOBJ_EXEC))
193 off += baseaddr;
194
195 /*
196 * if R_AMD64_RELATIVE, simply add base addr
197 * to reloc location
198 */
199
200 if (rtype == R_AMD64_RELATIVE) {
201 value = baseaddr;
202 } else {
203 /*
204 * get symbol table entry - if symbol is local
205 * value is base address of this object
206 */
207 symref = (Sym *)
208 (mp->symtbl+(stndx * mp->symhdr->sh_entsize));
209
210 if (ELF_ST_BIND(symref->st_info) == STB_LOCAL) {
211 /* *** this is different for .o and .so */
212 value = symref->st_value;
213 } else {
214 /*
215 * It's global. Allow weak references. If
216 * the symbol is undefined, give TNF (the
217 * kernel probes facility) a chance to see
218 * if it's a probe site, and fix it up if so.
219 */
220 if (symref->st_shndx == SHN_UNDEF &&
221 sdt_reloc_resolve(mp, mp->strings +
222 symref->st_name, (uint8_t *)off) == 0)
223 continue;
224
225 if (symref->st_shndx == SHN_UNDEF &&
226 tnf_reloc_resolve(mp->strings +
227 symref->st_name, &symref->st_value,
228 &addend, off, &probelist, &taglist) != 0) {
229 if (ELF_ST_BIND(symref->st_info)
230 != STB_WEAK) {
231 _kobj_printf(ops,
232 "not found: %s\n",
233 mp->strings +
234 symref->st_name);
235 err = 1;
236 }
237 continue;
238 } else { /* symbol found - relocate */
239 /*
240 * calculate location of definition
241 * - symbol value plus base address of
242 * containing shared object
243 */
244 value = symref->st_value;
245
246 } /* end else symbol found */
247 } /* end global or weak */
248 } /* end not R_AMD64_RELATIVE */
249
250 value += addend;
251 /*
252 * calculate final value -
253 * if PC-relative, subtract ref addr
254 */
255 if (IS_PC_RELATIVE(rtype))
256 value -= off;
257
258 #ifdef KOBJ_DEBUG
259 if (kobj_debug & D_RELOCATIONS) {
260 _kobj_printf(ops, "krtld:\t\t\t\t0x%8llx", off);
261 _kobj_printf(ops, " 0x%8llx\n", value);
262 }
263 #endif
264
265 if (do_reloc_krtld(rtype, (unsigned char *)off, &value,
266 (const char *)mp->strings + symref->st_name,
267 mp->filename) == 0)
268 err = 1;
269
270 } /* end of while loop */
271 if (err)
272 return (-1);
273
274 if (tnf_splice_probes(mp->flags & KOBJ_PRIM, probelist, taglist))
275 mp->flags |= KOBJ_TNF_PROBE;
276
277 return (0);
278 }
279
280 int
281 do_relocations(struct module *mp)
282 {
283 uint_t shn;
284 Shdr *shp, *rshp;
285 uint_t nreloc;
286
287 /* do the relocations */
288 for (shn = 1; shn < mp->hdr.e_shnum; shn++) {
289 rshp = (Shdr *)
290 (mp->shdrs + shn * mp->hdr.e_shentsize);
291 if (rshp->sh_type == SHT_REL) {
292 _kobj_printf(ops, "%s can't process type SHT_REL\n",
293 mp->filename);
294 return (-1);
295 }
296 if (rshp->sh_type != SHT_RELA)
297 continue;
298 if (rshp->sh_link != mp->symtbl_section) {
299 _kobj_printf(ops, "%s reloc for non-default symtab\n",
300 mp->filename);
301 return (-1);
302 }
303 if (rshp->sh_info >= mp->hdr.e_shnum) {
304 _kobj_printf(ops, "do_relocations: %s sh_info ",
305 mp->filename);
306 _kobj_printf(ops, "out of range %d\n", shn);
307 goto bad;
308 }
309 nreloc = rshp->sh_size / rshp->sh_entsize;
310
311 /* get the section header that this reloc table refers to */
312 shp = (Shdr *)
313 (mp->shdrs + rshp->sh_info * mp->hdr.e_shentsize);
314
315 /*
316 * Do not relocate any section that isn't loaded into memory.
317 * Most commonly this will skip over the .rela.stab* sections
318 */
319 if (!(shp->sh_flags & SHF_ALLOC))
320 continue;
321 #ifdef KOBJ_DEBUG
322 if (kobj_debug & D_RELOCATIONS) {
323 _kobj_printf(ops, "krtld: relocating: file=%s ",
324 mp->filename);
325 _kobj_printf(ops, "section=%d\n", shn);
326 }
327 #endif
328
329 if (do_relocate(mp, (char *)rshp->sh_addr, rshp->sh_type,
330 nreloc, rshp->sh_entsize, shp->sh_addr) < 0) {
331 _kobj_printf(ops,
332 "do_relocations: %s do_relocate failed\n",
333 mp->filename);
334 goto bad;
335 }
336 kobj_free((void *)rshp->sh_addr, rshp->sh_size);
337 rshp->sh_addr = 0;
338 }
339 mp->flags |= KOBJ_RELOCATED;
340 return (0);
341 bad:
342 kobj_free((void *)rshp->sh_addr, rshp->sh_size);
343 rshp->sh_addr = 0;
344 return (-1);
345 }