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 * Copyright 2020 Joyent, Inc.
27 */
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 do_relocate(struct module *mp, char *reltbl, int nreloc, int relocsize,
124 Addr baseaddr)
125 {
126 unsigned long stndx;
127 unsigned long off; /* can't be register for tnf_reloc_resolve() */
128 register unsigned long reladdr, rend;
129 register unsigned int rtype;
130 unsigned long value;
131 Elf64_Sxword addend;
132 Sym *symref = NULL;
133 int err = 0;
134 tnf_probe_control_t *probelist = NULL;
135 tnf_tag_data_t *taglist = NULL;
136 int symnum;
137 reladdr = (unsigned long)reltbl;
138 rend = reladdr + nreloc * relocsize;
139
140 #ifdef KOBJ_DEBUG
141 if (kobj_debug & D_RELOCATIONS) {
142 _kobj_printf(ops, "krtld:\ttype\t\t\toffset\t addend"
143 " symbol\n");
144 _kobj_printf(ops, "krtld:\t\t\t\t\t value\n");
145 }
146 #endif
147
148 symnum = -1;
149 /* loop through relocations */
150 while (reladdr < rend) {
151 symnum++;
152 rtype = ELF_R_TYPE(((Rela *)reladdr)->r_info);
153 off = ((Rela *)reladdr)->r_offset;
154 stndx = ELF_R_SYM(((Rela *)reladdr)->r_info);
155 if (stndx >= mp->nsyms) {
156 _kobj_printf(ops, "do_relocate: bad strndx %d\n",
157 symnum);
158 return (-1);
159 }
160 if ((rtype > R_AMD64_NUM) || IS_TLS_INS(rtype)) {
161 _kobj_printf(ops, "krtld: invalid relocation type %d",
162 rtype);
163 _kobj_printf(ops, " at 0x%lx:", off);
164 _kobj_printf(ops, " file=%s\n", mp->filename);
165 err = 1;
166 continue;
167 }
168
169
170 addend = (long)(((Rela *)reladdr)->r_addend);
171 reladdr += relocsize;
172
173
174 if (rtype == R_AMD64_NONE)
175 continue;
176
177 #ifdef KOBJ_DEBUG
178 if (kobj_debug & D_RELOCATIONS) {
179 Sym * symp;
180 symp = (Sym *)
181 (mp->symtbl+(stndx * mp->symhdr->sh_entsize));
182 _kobj_printf(ops, "krtld:\t%s",
183 conv_reloc_amd64_type(rtype));
184 _kobj_printf(ops, "\t0x%8lx", off);
185 _kobj_printf(ops, " %8lld", (longlong_t)addend);
186 _kobj_printf(ops, " %s\n",
187 (const char *)mp->strings + symp->st_name);
188 }
189 #endif
190
191 if (!(mp->flags & KOBJ_EXEC))
192 off += baseaddr;
193
194 /*
195 * if R_AMD64_RELATIVE, simply add base addr
196 * to reloc location
197 */
198
199 if (rtype == R_AMD64_RELATIVE) {
200 value = baseaddr;
201 } else {
202 /*
203 * get symbol table entry - if symbol is local
204 * value is base address of this object
205 */
206 symref = (Sym *)
207 (mp->symtbl+(stndx * mp->symhdr->sh_entsize));
208
209 if (ELF_ST_BIND(symref->st_info) == STB_LOCAL) {
210 /* *** this is different for .o and .so */
211 value = symref->st_value;
212 } else {
213 /*
214 * It's global. Allow weak references. If
215 * the symbol is undefined, give TNF (the
216 * kernel probes facility) a chance to see
217 * if it's a probe site, and fix it up if so.
218 */
219 if (symref->st_shndx == SHN_UNDEF &&
220 sdt_reloc_resolve(mp, mp->strings +
221 symref->st_name, (uint8_t *)off) == 0)
222 continue;
223
224 if (symref->st_shndx == SHN_UNDEF &&
225 tnf_reloc_resolve(mp->strings +
226 symref->st_name, &symref->st_value,
227 &addend, off, &probelist, &taglist) != 0) {
228 if (ELF_ST_BIND(symref->st_info)
229 != STB_WEAK) {
230 _kobj_printf(ops,
231 "not found: %s\n",
232 mp->strings +
233 symref->st_name);
234 err = 1;
235 }
236 continue;
237 } else { /* symbol found - relocate */
238 /*
239 * calculate location of definition
240 * - symbol value plus base address of
241 * containing shared object
242 */
243 value = symref->st_value;
244
245 } /* end else symbol found */
246 } /* end global or weak */
247 } /* end not R_AMD64_RELATIVE */
248
249 value += addend;
250 /*
251 * calculate final value -
252 * if PC-relative, subtract ref addr
253 */
254 if (IS_PC_RELATIVE(rtype))
255 value -= off;
256
257 #ifdef KOBJ_DEBUG
258 if (kobj_debug & D_RELOCATIONS) {
259 _kobj_printf(ops, "krtld:\t\t\t\t0x%8lx", off);
260 _kobj_printf(ops, " 0x%8lx\n", value);
261 }
262 #endif
263
264 if (do_reloc_krtld(rtype, (unsigned char *)off, &value,
265 (const char *)mp->strings + symref->st_name,
266 mp->filename) == 0)
267 err = 1;
268
269 } /* end of while loop */
270 if (err)
271 return (-1);
272
273 if (tnf_splice_probes(mp->flags & KOBJ_PRIM, probelist, taglist))
274 mp->flags |= KOBJ_TNF_PROBE;
275
276 return (0);
277 }
278
279 int
280 do_relocations(struct module *mp)
281 {
282 uint_t shn;
283 Shdr *shp, *rshp;
284 uint_t nreloc;
285
286 /* do the relocations */
287 for (shn = 1; shn < mp->hdr.e_shnum; shn++) {
288 rshp = (Shdr *)
289 (mp->shdrs + shn * mp->hdr.e_shentsize);
290 if (rshp->sh_type == SHT_REL) {
291 _kobj_printf(ops, "%s can't process type SHT_REL\n",
292 mp->filename);
293 return (-1);
294 }
295 if (rshp->sh_type != SHT_RELA)
296 continue;
297 if (rshp->sh_link != mp->symtbl_section) {
298 _kobj_printf(ops, "%s reloc for non-default symtab\n",
299 mp->filename);
300 return (-1);
301 }
302 if (rshp->sh_info >= mp->hdr.e_shnum) {
303 _kobj_printf(ops, "do_relocations: %s sh_info ",
304 mp->filename);
305 _kobj_printf(ops, "out of range %d\n", shn);
306 goto bad;
307 }
308 nreloc = rshp->sh_size / rshp->sh_entsize;
309
310 /* get the section header that this reloc table refers to */
311 shp = (Shdr *)
312 (mp->shdrs + rshp->sh_info * mp->hdr.e_shentsize);
313
314 /*
315 * Do not relocate any section that isn't loaded into memory.
316 * Most commonly this will skip over the .rela.stab* sections
317 */
318 if (!(shp->sh_flags & SHF_ALLOC))
319 continue;
320 #ifdef KOBJ_DEBUG
321 if (kobj_debug & D_RELOCATIONS) {
322 _kobj_printf(ops, "krtld: relocating: file=%s ",
323 mp->filename);
324 _kobj_printf(ops, "section=%d\n", shn);
325 }
326 #endif
327
328 if (do_relocate(mp, (char *)rshp->sh_addr, nreloc,
329 rshp->sh_entsize, shp->sh_addr) < 0) {
330 _kobj_printf(ops,
331 "do_relocations: %s do_relocate failed\n",
332 mp->filename);
333 goto bad;
334 }
335 kobj_free((void *)rshp->sh_addr, rshp->sh_size);
336 rshp->sh_addr = 0;
337 }
338 mp->flags |= KOBJ_RELOCATED;
339 return (0);
340 bad:
341 kobj_free((void *)rshp->sh_addr, rshp->sh_size);
342 rshp->sh_addr = 0;
343 return (-1);
344 }