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 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * Copyright (c) 2013 by Delphix. All rights reserved.
29 */
30
31 #define ELF_TARGET_ALL
32 #include <elf.h>
33
34 #include <sys/types.h>
35 #include <sys/sysmacros.h>
36
37 #include <unistd.h>
38 #include <strings.h>
39 #include <alloca.h>
40 #include <limits.h>
41 #include <stddef.h>
42 #include <stdlib.h>
43 #include <stdio.h>
44 #include <fcntl.h>
45 #include <errno.h>
46 #include <wait.h>
47 #include <assert.h>
48 #include <sys/ipc.h>
49
50 #include <dt_impl.h>
51 #include <dt_provider.h>
52 #include <dt_program.h>
53 #include <dt_string.h>
54
55 #define ESHDR_NULL 0
56 #define ESHDR_SHSTRTAB 1
57 #define ESHDR_DOF 2
58 #define ESHDR_STRTAB 3
59 #define ESHDR_SYMTAB 4
60 #define ESHDR_REL 5
61 #define ESHDR_NUM 6
62
63 #define PWRITE_SCN(index, data) \
64 (lseek64(fd, (off64_t)elf_file.shdr[(index)].sh_offset, SEEK_SET) != \
65 (off64_t)elf_file.shdr[(index)].sh_offset || \
66 dt_write(dtp, fd, (data), elf_file.shdr[(index)].sh_size) != \
67 elf_file.shdr[(index)].sh_size)
68
69 static const char DTRACE_SHSTRTAB32[] = "\0"
70 ".shstrtab\0" /* 1 */
71 ".SUNW_dof\0" /* 11 */
72 ".strtab\0" /* 21 */
73 ".symtab\0" /* 29 */
74 #ifdef __sparc
75 ".rela.SUNW_dof"; /* 37 */
76 #else
77 ".rel.SUNW_dof"; /* 37 */
78 #endif
79
80 static const char DTRACE_SHSTRTAB64[] = "\0"
81 ".shstrtab\0" /* 1 */
82 ".SUNW_dof\0" /* 11 */
83 ".strtab\0" /* 21 */
84 ".symtab\0" /* 29 */
85 ".rela.SUNW_dof"; /* 37 */
86
87 static const char DOFSTR[] = "__SUNW_dof";
88 static const char DOFLAZYSTR[] = "___SUNW_dof";
89
90 typedef struct dt_link_pair {
91 struct dt_link_pair *dlp_next; /* next pair in linked list */
92 void *dlp_str; /* buffer for string table */
93 void *dlp_sym; /* buffer for symbol table */
94 } dt_link_pair_t;
95
96 typedef struct dof_elf32 {
97 uint32_t de_nrel; /* relocation count */
98 #ifdef __sparc
99 Elf32_Rela *de_rel; /* array of relocations for sparc */
100 #else
101 Elf32_Rel *de_rel; /* array of relocations for x86 */
102 #endif
103 uint32_t de_nsym; /* symbol count */
104 Elf32_Sym *de_sym; /* array of symbols */
105 uint32_t de_strlen; /* size of of string table */
106 char *de_strtab; /* string table */
107 uint32_t de_global; /* index of the first global symbol */
108 } dof_elf32_t;
109
110 static int
111 prepare_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf32_t *dep)
112 {
113 dof_sec_t *dofs, *s;
114 dof_relohdr_t *dofrh;
115 dof_relodesc_t *dofr;
116 char *strtab;
117 int i, j, nrel;
118 size_t strtabsz = 1;
119 uint32_t count = 0;
120 size_t base;
121 Elf32_Sym *sym;
122 #ifdef __sparc
123 Elf32_Rela *rel;
124 #else
125 Elf32_Rel *rel;
126 #endif
127
128 /*LINTED*/
129 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff);
130
131 /*
132 * First compute the size of the string table and the number of
133 * relocations present in the DOF.
134 */
135 for (i = 0; i < dof->dofh_secnum; i++) {
136 if (dofs[i].dofs_type != DOF_SECT_URELHDR)
137 continue;
138
139 /*LINTED*/
140 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
141
142 s = &dofs[dofrh->dofr_strtab];
143 strtab = (char *)dof + s->dofs_offset;
144 assert(strtab[0] == '\0');
145 strtabsz += s->dofs_size - 1;
146
147 s = &dofs[dofrh->dofr_relsec];
148 /*LINTED*/
149 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
150 count += s->dofs_size / s->dofs_entsize;
151 }
152
153 dep->de_strlen = strtabsz;
154 dep->de_nrel = count;
155 dep->de_nsym = count + 1; /* the first symbol is always null */
156
157 if (dtp->dt_lazyload) {
158 dep->de_strlen += sizeof (DOFLAZYSTR);
159 dep->de_nsym++;
160 } else {
161 dep->de_strlen += sizeof (DOFSTR);
162 dep->de_nsym++;
163 }
164
165 if ((dep->de_rel = calloc(dep->de_nrel,
166 sizeof (dep->de_rel[0]))) == NULL) {
167 return (dt_set_errno(dtp, EDT_NOMEM));
168 }
169
170 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf32_Sym))) == NULL) {
171 free(dep->de_rel);
172 return (dt_set_errno(dtp, EDT_NOMEM));
173 }
174
175 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) {
176 free(dep->de_rel);
177 free(dep->de_sym);
178 return (dt_set_errno(dtp, EDT_NOMEM));
179 }
180
181 count = 0;
182 strtabsz = 1;
183 dep->de_strtab[0] = '\0';
184 rel = dep->de_rel;
185 sym = dep->de_sym;
186 dep->de_global = 1;
187
188 /*
189 * The first symbol table entry must be zeroed and is always ignored.
190 */
191 bzero(sym, sizeof (Elf32_Sym));
192 sym++;
193
194 /*
195 * Take a second pass through the DOF sections filling in the
196 * memory we allocated.
197 */
198 for (i = 0; i < dof->dofh_secnum; i++) {
199 if (dofs[i].dofs_type != DOF_SECT_URELHDR)
200 continue;
201
202 /*LINTED*/
203 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
204
205 s = &dofs[dofrh->dofr_strtab];
206 strtab = (char *)dof + s->dofs_offset;
207 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size);
208 base = strtabsz;
209 strtabsz += s->dofs_size - 1;
210
211 s = &dofs[dofrh->dofr_relsec];
212 /*LINTED*/
213 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
214 nrel = s->dofs_size / s->dofs_entsize;
215
216 s = &dofs[dofrh->dofr_tgtsec];
217
218 for (j = 0; j < nrel; j++) {
219 #if defined(__i386) || defined(__amd64)
220 rel->r_offset = s->dofs_offset +
221 dofr[j].dofr_offset;
222 rel->r_info = ELF32_R_INFO(count + dep->de_global,
223 R_386_32);
224 #elif defined(__sparc)
225 /*
226 * Add 4 bytes to hit the low half of this 64-bit
227 * big-endian address.
228 */
229 rel->r_offset = s->dofs_offset +
230 dofr[j].dofr_offset + 4;
231 rel->r_info = ELF32_R_INFO(count + dep->de_global,
232 R_SPARC_32);
233 #else
234 #error unknown ISA
235 #endif
236
237 sym->st_name = base + dofr[j].dofr_name - 1;
238 sym->st_value = 0;
239 sym->st_size = 0;
240 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_FUNC);
241 sym->st_other = 0;
242 sym->st_shndx = SHN_UNDEF;
243
244 rel++;
245 sym++;
246 count++;
247 }
248 }
249
250 /*
251 * Add a symbol for the DOF itself. We use a different symbol for
252 * lazily and actively loaded DOF to make them easy to distinguish.
253 */
254 sym->st_name = strtabsz;
255 sym->st_value = 0;
256 sym->st_size = dof->dofh_filesz;
257 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_OBJECT);
258 sym->st_other = 0;
259 sym->st_shndx = ESHDR_DOF;
260 sym++;
261
262 if (dtp->dt_lazyload) {
263 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz,
264 sizeof (DOFLAZYSTR));
265 strtabsz += sizeof (DOFLAZYSTR);
266 } else {
267 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR));
268 strtabsz += sizeof (DOFSTR);
269 }
270
271 assert(count == dep->de_nrel);
272 assert(strtabsz == dep->de_strlen);
273
274 return (0);
275 }
276
277
278 typedef struct dof_elf64 {
279 uint32_t de_nrel;
280 Elf64_Rela *de_rel;
281 uint32_t de_nsym;
282 Elf64_Sym *de_sym;
283
284 uint32_t de_strlen;
285 char *de_strtab;
286
287 uint32_t de_global;
288 } dof_elf64_t;
289
290 static int
291 prepare_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf64_t *dep)
292 {
293 dof_sec_t *dofs, *s;
294 dof_relohdr_t *dofrh;
295 dof_relodesc_t *dofr;
296 char *strtab;
297 int i, j, nrel;
298 size_t strtabsz = 1;
299 uint32_t count = 0;
300 size_t base;
301 Elf64_Sym *sym;
302 Elf64_Rela *rel;
303
304 /*LINTED*/
305 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff);
306
307 /*
308 * First compute the size of the string table and the number of
309 * relocations present in the DOF.
310 */
311 for (i = 0; i < dof->dofh_secnum; i++) {
312 if (dofs[i].dofs_type != DOF_SECT_URELHDR)
313 continue;
314
315 /*LINTED*/
316 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
317
318 s = &dofs[dofrh->dofr_strtab];
319 strtab = (char *)dof + s->dofs_offset;
320 assert(strtab[0] == '\0');
321 strtabsz += s->dofs_size - 1;
322
323 s = &dofs[dofrh->dofr_relsec];
324 /*LINTED*/
325 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
326 count += s->dofs_size / s->dofs_entsize;
327 }
328
329 dep->de_strlen = strtabsz;
330 dep->de_nrel = count;
331 dep->de_nsym = count + 1; /* the first symbol is always null */
332
333 if (dtp->dt_lazyload) {
334 dep->de_strlen += sizeof (DOFLAZYSTR);
335 dep->de_nsym++;
336 } else {
337 dep->de_strlen += sizeof (DOFSTR);
338 dep->de_nsym++;
339 }
340
341 if ((dep->de_rel = calloc(dep->de_nrel,
342 sizeof (dep->de_rel[0]))) == NULL) {
343 return (dt_set_errno(dtp, EDT_NOMEM));
344 }
345
346 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf64_Sym))) == NULL) {
347 free(dep->de_rel);
348 return (dt_set_errno(dtp, EDT_NOMEM));
349 }
350
351 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) {
352 free(dep->de_rel);
353 free(dep->de_sym);
354 return (dt_set_errno(dtp, EDT_NOMEM));
355 }
356
357 count = 0;
358 strtabsz = 1;
359 dep->de_strtab[0] = '\0';
360 rel = dep->de_rel;
361 sym = dep->de_sym;
362 dep->de_global = 1;
363
364 /*
365 * The first symbol table entry must be zeroed and is always ignored.
366 */
367 bzero(sym, sizeof (Elf64_Sym));
368 sym++;
369
370 /*
371 * Take a second pass through the DOF sections filling in the
372 * memory we allocated.
373 */
374 for (i = 0; i < dof->dofh_secnum; i++) {
375 if (dofs[i].dofs_type != DOF_SECT_URELHDR)
376 continue;
377
378 /*LINTED*/
379 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
380
381 s = &dofs[dofrh->dofr_strtab];
382 strtab = (char *)dof + s->dofs_offset;
383 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size);
384 base = strtabsz;
385 strtabsz += s->dofs_size - 1;
386
387 s = &dofs[dofrh->dofr_relsec];
388 /*LINTED*/
389 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
390 nrel = s->dofs_size / s->dofs_entsize;
391
392 s = &dofs[dofrh->dofr_tgtsec];
393
394 for (j = 0; j < nrel; j++) {
395 #if defined(__i386) || defined(__amd64)
396 rel->r_offset = s->dofs_offset +
397 dofr[j].dofr_offset;
398 rel->r_info = ELF64_R_INFO(count + dep->de_global,
399 R_AMD64_64);
400 #elif defined(__sparc)
401 rel->r_offset = s->dofs_offset +
402 dofr[j].dofr_offset;
403 rel->r_info = ELF64_R_INFO(count + dep->de_global,
404 R_SPARC_64);
405 #else
406 #error unknown ISA
407 #endif
408
409 sym->st_name = base + dofr[j].dofr_name - 1;
410 sym->st_value = 0;
411 sym->st_size = 0;
412 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_FUNC);
413 sym->st_other = 0;
414 sym->st_shndx = SHN_UNDEF;
415
416 rel++;
417 sym++;
418 count++;
419 }
420 }
421
422 /*
423 * Add a symbol for the DOF itself. We use a different symbol for
424 * lazily and actively loaded DOF to make them easy to distinguish.
425 */
426 sym->st_name = strtabsz;
427 sym->st_value = 0;
428 sym->st_size = dof->dofh_filesz;
429 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_OBJECT);
430 sym->st_other = 0;
431 sym->st_shndx = ESHDR_DOF;
432 sym++;
433
434 if (dtp->dt_lazyload) {
435 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz,
436 sizeof (DOFLAZYSTR));
437 strtabsz += sizeof (DOFLAZYSTR);
438 } else {
439 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR));
440 strtabsz += sizeof (DOFSTR);
441 }
442
443 assert(count == dep->de_nrel);
444 assert(strtabsz == dep->de_strlen);
445
446 return (0);
447 }
448
449 /*
450 * Write out an ELF32 file prologue consisting of a header, section headers,
451 * and a section header string table. The DOF data will follow this prologue
452 * and complete the contents of the given ELF file.
453 */
454 static int
455 dump_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd)
456 {
457 struct {
458 Elf32_Ehdr ehdr;
459 Elf32_Shdr shdr[ESHDR_NUM];
460 } elf_file;
461
462 Elf32_Shdr *shp;
463 Elf32_Off off;
464 dof_elf32_t de;
465 int ret = 0;
466 uint_t nshdr;
467
468 if (prepare_elf32(dtp, dof, &de) != 0)
469 return (-1); /* errno is set for us */
470
471 /*
472 * If there are no relocations, we only need enough sections for
473 * the shstrtab and the DOF.
474 */
475 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM;
476
477 bzero(&elf_file, sizeof (elf_file));
478
479 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0;
480 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1;
481 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2;
482 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3;
483 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT;
484 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS32;
485 #if defined(_BIG_ENDIAN)
486 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB;
487 #elif defined(_LITTLE_ENDIAN)
488 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
489 #endif
490 elf_file.ehdr.e_type = ET_REL;
491 #if defined(__sparc)
492 elf_file.ehdr.e_machine = EM_SPARC;
493 #elif defined(__i386) || defined(__amd64)
494 elf_file.ehdr.e_machine = EM_386;
495 #endif
496 elf_file.ehdr.e_version = EV_CURRENT;
497 elf_file.ehdr.e_shoff = sizeof (Elf32_Ehdr);
498 elf_file.ehdr.e_ehsize = sizeof (Elf32_Ehdr);
499 elf_file.ehdr.e_phentsize = sizeof (Elf32_Phdr);
500 elf_file.ehdr.e_shentsize = sizeof (Elf32_Shdr);
501 elf_file.ehdr.e_shnum = nshdr;
502 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB;
503 off = sizeof (elf_file) + nshdr * sizeof (Elf32_Shdr);
504
505 shp = &elf_file.shdr[ESHDR_SHSTRTAB];
506 shp->sh_name = 1; /* DTRACE_SHSTRTAB32[1] = ".shstrtab" */
507 shp->sh_type = SHT_STRTAB;
508 shp->sh_offset = off;
509 shp->sh_size = sizeof (DTRACE_SHSTRTAB32);
510 shp->sh_addralign = sizeof (char);
511 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
512
513 shp = &elf_file.shdr[ESHDR_DOF];
514 shp->sh_name = 11; /* DTRACE_SHSTRTAB32[11] = ".SUNW_dof" */
515 shp->sh_flags = SHF_ALLOC;
516 shp->sh_type = SHT_SUNW_dof;
517 shp->sh_offset = off;
518 shp->sh_size = dof->dofh_filesz;
519 shp->sh_addralign = 8;
520 off = shp->sh_offset + shp->sh_size;
521
522 shp = &elf_file.shdr[ESHDR_STRTAB];
523 shp->sh_name = 21; /* DTRACE_SHSTRTAB32[21] = ".strtab" */
524 shp->sh_flags = SHF_ALLOC;
525 shp->sh_type = SHT_STRTAB;
526 shp->sh_offset = off;
527 shp->sh_size = de.de_strlen;
528 shp->sh_addralign = sizeof (char);
529 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4);
530
531 shp = &elf_file.shdr[ESHDR_SYMTAB];
532 shp->sh_name = 29; /* DTRACE_SHSTRTAB32[29] = ".symtab" */
533 shp->sh_flags = SHF_ALLOC;
534 shp->sh_type = SHT_SYMTAB;
535 shp->sh_entsize = sizeof (Elf32_Sym);
536 shp->sh_link = ESHDR_STRTAB;
537 shp->sh_offset = off;
538 shp->sh_info = de.de_global;
539 shp->sh_size = de.de_nsym * sizeof (Elf32_Sym);
540 shp->sh_addralign = 4;
541 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4);
542
543 if (de.de_nrel == 0) {
544 if (dt_write(dtp, fd, &elf_file,
545 sizeof (elf_file)) != sizeof (elf_file) ||
546 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) ||
547 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
548 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
549 PWRITE_SCN(ESHDR_DOF, dof)) {
550 ret = dt_set_errno(dtp, errno);
551 }
552 } else {
553 shp = &elf_file.shdr[ESHDR_REL];
554 shp->sh_name = 37; /* DTRACE_SHSTRTAB32[37] = ".rel.SUNW_dof" */
555 shp->sh_flags = SHF_ALLOC;
556 #ifdef __sparc
557 shp->sh_type = SHT_RELA;
558 #else
559 shp->sh_type = SHT_REL;
560 #endif
561 shp->sh_entsize = sizeof (de.de_rel[0]);
562 shp->sh_link = ESHDR_SYMTAB;
563 shp->sh_info = ESHDR_DOF;
564 shp->sh_offset = off;
565 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]);
566 shp->sh_addralign = 4;
567
568 if (dt_write(dtp, fd, &elf_file,
569 sizeof (elf_file)) != sizeof (elf_file) ||
570 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) ||
571 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
572 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
573 PWRITE_SCN(ESHDR_REL, de.de_rel) ||
574 PWRITE_SCN(ESHDR_DOF, dof)) {
575 ret = dt_set_errno(dtp, errno);
576 }
577 }
578
579 free(de.de_strtab);
580 free(de.de_sym);
581 free(de.de_rel);
582
583 return (ret);
584 }
585
586 /*
587 * Write out an ELF64 file prologue consisting of a header, section headers,
588 * and a section header string table. The DOF data will follow this prologue
589 * and complete the contents of the given ELF file.
590 */
591 static int
592 dump_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd)
593 {
594 struct {
595 Elf64_Ehdr ehdr;
596 Elf64_Shdr shdr[ESHDR_NUM];
597 } elf_file;
598
599 Elf64_Shdr *shp;
600 Elf64_Off off;
601 dof_elf64_t de;
602 int ret = 0;
603 uint_t nshdr;
604
605 if (prepare_elf64(dtp, dof, &de) != 0)
606 return (-1); /* errno is set for us */
607
608 /*
609 * If there are no relocations, we only need enough sections for
610 * the shstrtab and the DOF.
611 */
612 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM;
613
614 bzero(&elf_file, sizeof (elf_file));
615
616 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0;
617 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1;
618 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2;
619 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3;
620 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT;
621 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS64;
622 #if defined(_BIG_ENDIAN)
623 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB;
624 #elif defined(_LITTLE_ENDIAN)
625 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
626 #endif
627 elf_file.ehdr.e_type = ET_REL;
628 #if defined(__sparc)
629 elf_file.ehdr.e_machine = EM_SPARCV9;
630 #elif defined(__i386) || defined(__amd64)
631 elf_file.ehdr.e_machine = EM_AMD64;
632 #endif
633 elf_file.ehdr.e_version = EV_CURRENT;
634 elf_file.ehdr.e_shoff = sizeof (Elf64_Ehdr);
635 elf_file.ehdr.e_ehsize = sizeof (Elf64_Ehdr);
636 elf_file.ehdr.e_phentsize = sizeof (Elf64_Phdr);
637 elf_file.ehdr.e_shentsize = sizeof (Elf64_Shdr);
638 elf_file.ehdr.e_shnum = nshdr;
639 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB;
640 off = sizeof (elf_file) + nshdr * sizeof (Elf64_Shdr);
641
642 shp = &elf_file.shdr[ESHDR_SHSTRTAB];
643 shp->sh_name = 1; /* DTRACE_SHSTRTAB64[1] = ".shstrtab" */
644 shp->sh_type = SHT_STRTAB;
645 shp->sh_offset = off;
646 shp->sh_size = sizeof (DTRACE_SHSTRTAB64);
647 shp->sh_addralign = sizeof (char);
648 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
649
650 shp = &elf_file.shdr[ESHDR_DOF];
651 shp->sh_name = 11; /* DTRACE_SHSTRTAB64[11] = ".SUNW_dof" */
652 shp->sh_flags = SHF_ALLOC;
653 shp->sh_type = SHT_SUNW_dof;
654 shp->sh_offset = off;
655 shp->sh_size = dof->dofh_filesz;
656 shp->sh_addralign = 8;
657 off = shp->sh_offset + shp->sh_size;
658
659 shp = &elf_file.shdr[ESHDR_STRTAB];
660 shp->sh_name = 21; /* DTRACE_SHSTRTAB64[21] = ".strtab" */
661 shp->sh_flags = SHF_ALLOC;
662 shp->sh_type = SHT_STRTAB;
663 shp->sh_offset = off;
664 shp->sh_size = de.de_strlen;
665 shp->sh_addralign = sizeof (char);
666 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
667
668 shp = &elf_file.shdr[ESHDR_SYMTAB];
669 shp->sh_name = 29; /* DTRACE_SHSTRTAB64[29] = ".symtab" */
670 shp->sh_flags = SHF_ALLOC;
671 shp->sh_type = SHT_SYMTAB;
672 shp->sh_entsize = sizeof (Elf64_Sym);
673 shp->sh_link = ESHDR_STRTAB;
674 shp->sh_offset = off;
675 shp->sh_info = de.de_global;
676 shp->sh_size = de.de_nsym * sizeof (Elf64_Sym);
677 shp->sh_addralign = 8;
678 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
679
680 if (de.de_nrel == 0) {
681 if (dt_write(dtp, fd, &elf_file,
682 sizeof (elf_file)) != sizeof (elf_file) ||
683 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) ||
684 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
685 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
686 PWRITE_SCN(ESHDR_DOF, dof)) {
687 ret = dt_set_errno(dtp, errno);
688 }
689 } else {
690 shp = &elf_file.shdr[ESHDR_REL];
691 shp->sh_name = 37; /* DTRACE_SHSTRTAB64[37] = ".rel.SUNW_dof" */
692 shp->sh_flags = SHF_ALLOC;
693 shp->sh_type = SHT_RELA;
694 shp->sh_entsize = sizeof (de.de_rel[0]);
695 shp->sh_link = ESHDR_SYMTAB;
696 shp->sh_info = ESHDR_DOF;
697 shp->sh_offset = off;
698 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]);
699 shp->sh_addralign = 8;
700
701 if (dt_write(dtp, fd, &elf_file,
702 sizeof (elf_file)) != sizeof (elf_file) ||
703 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) ||
704 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
705 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
706 PWRITE_SCN(ESHDR_REL, de.de_rel) ||
707 PWRITE_SCN(ESHDR_DOF, dof)) {
708 ret = dt_set_errno(dtp, errno);
709 }
710 }
711
712 free(de.de_strtab);
713 free(de.de_sym);
714 free(de.de_rel);
715
716 return (ret);
717 }
718
719 static int
720 dt_symtab_lookup(Elf_Data *data_sym, int nsym, uintptr_t addr, uint_t shn,
721 GElf_Sym *sym)
722 {
723 int i, ret = -1;
724 GElf_Sym s;
725
726 for (i = 0; i < nsym && gelf_getsym(data_sym, i, sym) != NULL; i++) {
727 if (GELF_ST_TYPE(sym->st_info) == STT_FUNC &&
728 shn == sym->st_shndx &&
729 sym->st_value <= addr &&
730 addr < sym->st_value + sym->st_size) {
731 if (GELF_ST_BIND(sym->st_info) == STB_GLOBAL)
732 return (0);
733
734 ret = 0;
735 s = *sym;
736 }
737 }
738
739 if (ret == 0)
740 *sym = s;
741 return (ret);
742 }
743
744 #if defined(__sparc)
745
746 #define DT_OP_RET 0x81c7e008
747 #define DT_OP_NOP 0x01000000
748 #define DT_OP_CALL 0x40000000
749 #define DT_OP_CLR_O0 0x90102000
750
751 #define DT_IS_MOV_O7(inst) (((inst) & 0xffffe000) == 0x9e100000)
752 #define DT_IS_RESTORE(inst) (((inst) & 0xc1f80000) == 0x81e80000)
753 #define DT_IS_RETL(inst) (((inst) & 0xfff83fff) == 0x81c02008)
754
755 #define DT_RS2(inst) ((inst) & 0x1f)
756 #define DT_MAKE_RETL(reg) (0x81c02008 | ((reg) << 14))
757
758 /*ARGSUSED*/
759 static int
760 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela,
761 uint32_t *off)
762 {
763 uint32_t *ip;
764
765 if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0)
766 return (-1);
767
768 /*LINTED*/
769 ip = (uint32_t *)(p + rela->r_offset);
770
771 /*
772 * We only know about some specific relocation types.
773 */
774 if (GELF_R_TYPE(rela->r_info) != R_SPARC_WDISP30 &&
775 GELF_R_TYPE(rela->r_info) != R_SPARC_WPLT30)
776 return (-1);
777
778 /*
779 * We may have already processed this object file in an earlier linker
780 * invocation. Check to see if the present instruction sequence matches
781 * the one we would install below.
782 */
783 if (isenabled) {
784 if (ip[0] == DT_OP_NOP) {
785 (*off) += sizeof (ip[0]);
786 return (0);
787 }
788 } else {
789 if (DT_IS_RESTORE(ip[1])) {
790 if (ip[0] == DT_OP_RET) {
791 (*off) += sizeof (ip[0]);
792 return (0);
793 }
794 } else if (DT_IS_MOV_O7(ip[1])) {
795 if (DT_IS_RETL(ip[0]))
796 return (0);
797 } else {
798 if (ip[0] == DT_OP_NOP) {
799 (*off) += sizeof (ip[0]);
800 return (0);
801 }
802 }
803 }
804
805 /*
806 * We only expect call instructions with a displacement of 0.
807 */
808 if (ip[0] != DT_OP_CALL) {
809 dt_dprintf("found %x instead of a call instruction at %llx\n",
810 ip[0], (u_longlong_t)rela->r_offset);
811 return (-1);
812 }
813
814 if (isenabled) {
815 /*
816 * It would necessarily indicate incorrect usage if an is-
817 * enabled probe were tail-called so flag that as an error.
818 * It's also potentially (very) tricky to handle gracefully,
819 * but could be done if this were a desired use scenario.
820 */
821 if (DT_IS_RESTORE(ip[1]) || DT_IS_MOV_O7(ip[1])) {
822 dt_dprintf("tail call to is-enabled probe at %llx\n",
823 (u_longlong_t)rela->r_offset);
824 return (-1);
825 }
826
827
828 /*
829 * On SPARC, we take advantage of the fact that the first
830 * argument shares the same register as for the return value.
831 * The macro handles the work of zeroing that register so we
832 * don't need to do anything special here. We instrument the
833 * instruction in the delay slot as we'll need to modify the
834 * return register after that instruction has been emulated.
835 */
836 ip[0] = DT_OP_NOP;
837 (*off) += sizeof (ip[0]);
838 } else {
839 /*
840 * If the call is followed by a restore, it's a tail call so
841 * change the call to a ret. If the call if followed by a mov
842 * of a register into %o7, it's a tail call in leaf context
843 * so change the call to a retl-like instruction that returns
844 * to that register value + 8 (rather than the typical %o7 +
845 * 8); the delay slot instruction is left, but should have no
846 * effect. Otherwise we change the call to be a nop. We
847 * identify the subsequent instruction as the probe point in
848 * all but the leaf tail-call case to ensure that arguments to
849 * the probe are complete and consistent. An astute, though
850 * largely hypothetical, observer would note that there is the
851 * possibility of a false-positive probe firing if the function
852 * contained a branch to the instruction in the delay slot of
853 * the call. Fixing this would require significant in-kernel
854 * modifications, and isn't worth doing until we see it in the
855 * wild.
856 */
857 if (DT_IS_RESTORE(ip[1])) {
858 ip[0] = DT_OP_RET;
859 (*off) += sizeof (ip[0]);
860 } else if (DT_IS_MOV_O7(ip[1])) {
861 ip[0] = DT_MAKE_RETL(DT_RS2(ip[1]));
862 } else {
863 ip[0] = DT_OP_NOP;
864 (*off) += sizeof (ip[0]);
865 }
866 }
867
868 return (0);
869 }
870
871 #elif defined(__i386) || defined(__amd64)
872
873 #define DT_OP_NOP 0x90
874 #define DT_OP_RET 0xc3
875 #define DT_OP_CALL 0xe8
876 #define DT_OP_JMP32 0xe9
877 #define DT_OP_REX_RAX 0x48
878 #define DT_OP_XOR_EAX_0 0x33
879 #define DT_OP_XOR_EAX_1 0xc0
880
881 static int
882 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela,
883 uint32_t *off)
884 {
885 uint8_t *ip = (uint8_t *)(p + rela->r_offset - 1);
886 uint8_t ret;
887
888 /*
889 * On x86, the first byte of the instruction is the call opcode and
890 * the next four bytes are the 32-bit address; the relocation is for
891 * the address operand. We back up the offset to the first byte of
892 * the instruction. For is-enabled probes, we later advance the offset
893 * so that it hits the first nop in the instruction sequence.
894 */
895 (*off) -= 1;
896
897 /*
898 * We only know about some specific relocation types. Luckily
899 * these types have the same values on both 32-bit and 64-bit
900 * x86 architectures.
901 */
902 if (GELF_R_TYPE(rela->r_info) != R_386_PC32 &&
903 GELF_R_TYPE(rela->r_info) != R_386_PLT32)
904 return (-1);
905
906 /*
907 * We may have already processed this object file in an earlier linker
908 * invocation. Check to see if the present instruction sequence matches
909 * the one we would install. For is-enabled probes, we advance the
910 * offset to the first nop instruction in the sequence to match the
911 * text modification code below.
912 */
913 if (!isenabled) {
914 if ((ip[0] == DT_OP_NOP || ip[0] == DT_OP_RET) &&
915 ip[1] == DT_OP_NOP && ip[2] == DT_OP_NOP &&
916 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP)
917 return (0);
918 } else if (dtp->dt_oflags & DTRACE_O_LP64) {
919 if (ip[0] == DT_OP_REX_RAX &&
920 ip[1] == DT_OP_XOR_EAX_0 && ip[2] == DT_OP_XOR_EAX_1 &&
921 (ip[3] == DT_OP_NOP || ip[3] == DT_OP_RET) &&
922 ip[4] == DT_OP_NOP) {
923 (*off) += 3;
924 return (0);
925 }
926 } else {
927 if (ip[0] == DT_OP_XOR_EAX_0 && ip[1] == DT_OP_XOR_EAX_1 &&
928 (ip[2] == DT_OP_NOP || ip[2] == DT_OP_RET) &&
929 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) {
930 (*off) += 2;
931 return (0);
932 }
933 }
934
935 /*
936 * We expect either a call instrution with a 32-bit displacement or a
937 * jmp instruction with a 32-bit displacement acting as a tail-call.
938 */
939 if (ip[0] != DT_OP_CALL && ip[0] != DT_OP_JMP32) {
940 dt_dprintf("found %x instead of a call or jmp instruction at "
941 "%llx\n", ip[0], (u_longlong_t)rela->r_offset);
942 return (-1);
943 }
944
945 ret = (ip[0] == DT_OP_JMP32) ? DT_OP_RET : DT_OP_NOP;
946
947 /*
948 * Establish the instruction sequence -- all nops for probes, and an
949 * instruction to clear the return value register (%eax/%rax) followed
950 * by nops for is-enabled probes. For is-enabled probes, we advance
951 * the offset to the first nop. This isn't stricly necessary but makes
952 * for more readable disassembly when the probe is enabled.
953 */
954 if (!isenabled) {
955 ip[0] = ret;
956 ip[1] = DT_OP_NOP;
957 ip[2] = DT_OP_NOP;
958 ip[3] = DT_OP_NOP;
959 ip[4] = DT_OP_NOP;
960 } else if (dtp->dt_oflags & DTRACE_O_LP64) {
961 ip[0] = DT_OP_REX_RAX;
962 ip[1] = DT_OP_XOR_EAX_0;
963 ip[2] = DT_OP_XOR_EAX_1;
964 ip[3] = ret;
965 ip[4] = DT_OP_NOP;
966 (*off) += 3;
967 } else {
968 ip[0] = DT_OP_XOR_EAX_0;
969 ip[1] = DT_OP_XOR_EAX_1;
970 ip[2] = ret;
971 ip[3] = DT_OP_NOP;
972 ip[4] = DT_OP_NOP;
973 (*off) += 2;
974 }
975
976 return (0);
977 }
978
979 #else
980 #error unknown ISA
981 #endif
982
983 /*PRINTFLIKE5*/
984 static int
985 dt_link_error(dtrace_hdl_t *dtp, Elf *elf, int fd, dt_link_pair_t *bufs,
986 const char *format, ...)
987 {
988 va_list ap;
989 dt_link_pair_t *pair;
990
991 va_start(ap, format);
992 dt_set_errmsg(dtp, NULL, NULL, NULL, 0, format, ap);
993 va_end(ap);
994
995 if (elf != NULL)
996 (void) elf_end(elf);
997
998 if (fd >= 0)
999 (void) close(fd);
1000
1001 while ((pair = bufs) != NULL) {
1002 bufs = pair->dlp_next;
1003 dt_free(dtp, pair->dlp_str);
1004 dt_free(dtp, pair->dlp_sym);
1005 dt_free(dtp, pair);
1006 }
1007
1008 return (dt_set_errno(dtp, EDT_COMPILER));
1009 }
1010
1011 static int
1012 process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp)
1013 {
1014 static const char dt_prefix[] = "__dtrace";
1015 static const char dt_enabled[] = "enabled";
1016 static const char dt_symprefix[] = "$dtrace";
1017 static const char dt_symfmt[] = "%s%d.%s";
1018 int fd, i, ndx, eprobe, mod = 0;
1019 Elf *elf = NULL;
1020 GElf_Ehdr ehdr;
1021 Elf_Scn *scn_rel, *scn_sym, *scn_str, *scn_tgt;
1022 Elf_Data *data_rel, *data_sym, *data_str, *data_tgt;
1023 GElf_Shdr shdr_rel, shdr_sym, shdr_str, shdr_tgt;
1024 GElf_Sym rsym, fsym, dsym;
1025 GElf_Rela rela;
1026 char *s, *p, *r;
1027 char pname[DTRACE_PROVNAMELEN];
1028 dt_provider_t *pvp;
1029 dt_probe_t *prp;
1030 uint32_t off, eclass, emachine1, emachine2;
1031 size_t symsize, nsym, isym, istr, len;
1032 key_t objkey;
1033 dt_link_pair_t *pair, *bufs = NULL;
1034 dt_strtab_t *strtab;
1035 Elf_Data *data_newsym, *data_newstr;
1036 size_t newsym = 0;
1037
1038 if ((fd = open64(obj, O_RDWR)) == -1) {
1039 return (dt_link_error(dtp, elf, fd, bufs,
1040 "failed to open %s: %s", obj, strerror(errno)));
1041 }
1042
1043 if ((elf = elf_begin(fd, ELF_C_RDWR, NULL)) == NULL) {
1044 return (dt_link_error(dtp, elf, fd, bufs,
1045 "failed to process %s: %s", obj, elf_errmsg(elf_errno())));
1046 }
1047
1048 switch (elf_kind(elf)) {
1049 case ELF_K_ELF:
1050 break;
1051 case ELF_K_AR:
1052 return (dt_link_error(dtp, elf, fd, bufs, "archives are not "
1053 "permitted; use the contents of the archive instead: %s",
1054 obj));
1055 default:
1056 return (dt_link_error(dtp, elf, fd, bufs,
1057 "invalid file type: %s", obj));
1058 }
1059
1060 if (gelf_getehdr(elf, &ehdr) == NULL) {
1061 return (dt_link_error(dtp, elf, fd, bufs, "corrupt file: %s",
1062 obj));
1063 }
1064
1065 if (dtp->dt_oflags & DTRACE_O_LP64) {
1066 eclass = ELFCLASS64;
1067 #if defined(__sparc)
1068 emachine1 = emachine2 = EM_SPARCV9;
1069 #elif defined(__i386) || defined(__amd64)
1070 emachine1 = emachine2 = EM_AMD64;
1071 #endif
1072 symsize = sizeof (Elf64_Sym);
1073 } else {
1074 eclass = ELFCLASS32;
1075 #if defined(__sparc)
1076 emachine1 = EM_SPARC;
1077 emachine2 = EM_SPARC32PLUS;
1078 #elif defined(__i386) || defined(__amd64)
1079 emachine1 = emachine2 = EM_386;
1080 #endif
1081 symsize = sizeof (Elf32_Sym);
1082 }
1083
1084 if (ehdr.e_ident[EI_CLASS] != eclass) {
1085 return (dt_link_error(dtp, elf, fd, bufs,
1086 "incorrect ELF class for object file: %s", obj));
1087 }
1088
1089 if (ehdr.e_machine != emachine1 && ehdr.e_machine != emachine2) {
1090 return (dt_link_error(dtp, elf, fd, bufs,
1091 "incorrect ELF machine type for object file: %s", obj));
1092 }
1093
1094 /*
1095 * We use this token as a relatively unique handle for this file on the
1096 * system in order to disambiguate potential conflicts between files of
1097 * the same name which contain identially named local symbols.
1098 */
1099 if ((objkey = ftok(obj, 0)) == (key_t)-1) {
1100 return (dt_link_error(dtp, elf, fd, bufs,
1101 "failed to generate unique key for object file: %s", obj));
1102 }
1103
1104 scn_rel = NULL;
1105 while ((scn_rel = elf_nextscn(elf, scn_rel)) != NULL) {
1106 if (gelf_getshdr(scn_rel, &shdr_rel) == NULL)
1107 goto err;
1108
1109 /*
1110 * Skip any non-relocation sections.
1111 */
1112 if (shdr_rel.sh_type != SHT_RELA && shdr_rel.sh_type != SHT_REL)
1113 continue;
1114
1115 if ((data_rel = elf_getdata(scn_rel, NULL)) == NULL)
1116 goto err;
1117
1118 /*
1119 * Grab the section, section header and section data for the
1120 * symbol table that this relocation section references.
1121 */
1122 if ((scn_sym = elf_getscn(elf, shdr_rel.sh_link)) == NULL ||
1123 gelf_getshdr(scn_sym, &shdr_sym) == NULL ||
1124 (data_sym = elf_getdata(scn_sym, NULL)) == NULL)
1125 goto err;
1126
1127 /*
1128 * Ditto for that symbol table's string table.
1129 */
1130 if ((scn_str = elf_getscn(elf, shdr_sym.sh_link)) == NULL ||
1131 gelf_getshdr(scn_str, &shdr_str) == NULL ||
1132 (data_str = elf_getdata(scn_str, NULL)) == NULL)
1133 goto err;
1134
1135 /*
1136 * Grab the section, section header and section data for the
1137 * target section for the relocations. For the relocations
1138 * we're looking for -- this will typically be the text of the
1139 * object file.
1140 */
1141 if ((scn_tgt = elf_getscn(elf, shdr_rel.sh_info)) == NULL ||
1142 gelf_getshdr(scn_tgt, &shdr_tgt) == NULL ||
1143 (data_tgt = elf_getdata(scn_tgt, NULL)) == NULL)
1144 goto err;
1145
1146 /*
1147 * We're looking for relocations to symbols matching this form:
1148 *
1149 * __dtrace[enabled]_<prov>___<probe>
1150 *
1151 * For the generated object, we need to record the location
1152 * identified by the relocation, and create a new relocation
1153 * in the generated object that will be resolved at link time
1154 * to the location of the function in which the probe is
1155 * embedded. In the target object, we change the matched symbol
1156 * so that it will be ignored at link time, and we modify the
1157 * target (text) section to replace the call instruction with
1158 * one or more nops.
1159 *
1160 * If the function containing the probe is locally scoped
1161 * (static), we create an alias used by the relocation in the
1162 * generated object. The alias, a new symbol, will be global
1163 * (so that the relocation from the generated object can be
1164 * resolved), and hidden (so that it is converted to a local
1165 * symbol at link time). Such aliases have this form:
1166 *
1167 * $dtrace<key>.<function>
1168 *
1169 * We take a first pass through all the relocations to
1170 * populate our string table and count the number of extra
1171 * symbols we'll require.
1172 */
1173 strtab = dt_strtab_create(1);
1174 nsym = 0;
1175 isym = data_sym->d_size / symsize;
1176 istr = data_str->d_size;
1177
1178 for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) {
1179
1180 if (shdr_rel.sh_type == SHT_RELA) {
1181 if (gelf_getrela(data_rel, i, &rela) == NULL)
1182 continue;
1183 } else {
1184 GElf_Rel rel;
1185 if (gelf_getrel(data_rel, i, &rel) == NULL)
1186 continue;
1187 rela.r_offset = rel.r_offset;
1188 rela.r_info = rel.r_info;
1189 rela.r_addend = 0;
1190 }
1191
1192 if (gelf_getsym(data_sym, GELF_R_SYM(rela.r_info),
1193 &rsym) == NULL) {
1194 dt_strtab_destroy(strtab);
1195 goto err;
1196 }
1197
1198 s = (char *)data_str->d_buf + rsym.st_name;
1199
1200 if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0)
1201 continue;
1202
1203 if (dt_symtab_lookup(data_sym, isym, rela.r_offset,
1204 shdr_rel.sh_info, &fsym) != 0) {
1205 dt_strtab_destroy(strtab);
1206 goto err;
1207 }
1208
1209 if (GELF_ST_BIND(fsym.st_info) != STB_LOCAL)
1210 continue;
1211
1212 if (fsym.st_name > data_str->d_size) {
1213 dt_strtab_destroy(strtab);
1214 goto err;
1215 }
1216
1217 s = (char *)data_str->d_buf + fsym.st_name;
1218
1219 /*
1220 * If this symbol isn't of type function, we've really
1221 * driven off the rails or the object file is corrupt.
1222 */
1223 if (GELF_ST_TYPE(fsym.st_info) != STT_FUNC) {
1224 dt_strtab_destroy(strtab);
1225 return (dt_link_error(dtp, elf, fd, bufs,
1226 "expected %s to be of type function", s));
1227 }
1228
1229 len = snprintf(NULL, 0, dt_symfmt, dt_symprefix,
1230 objkey, s) + 1;
1231 if ((p = dt_alloc(dtp, len)) == NULL) {
1232 dt_strtab_destroy(strtab);
1233 goto err;
1234 }
1235 (void) snprintf(p, len, dt_symfmt, dt_symprefix,
1236 objkey, s);
1237
1238 if (dt_strtab_index(strtab, p) == -1) {
1239 nsym++;
1240 (void) dt_strtab_insert(strtab, p);
1241 }
1242
1243 dt_free(dtp, p);
1244 }
1245
1246 /*
1247 * If needed, allocate the additional space for the symbol
1248 * table and string table copying the old data into the new
1249 * buffers, and marking the buffers as dirty. We inject those
1250 * newly allocated buffers into the libelf data structures, but
1251 * are still responsible for freeing them once we're done with
1252 * the elf handle.
1253 */
1254 if (nsym > 0) {
1255 /*
1256 * The first byte of the string table is reserved for
1257 * the \0 entry.
1258 */
1259 len = dt_strtab_size(strtab) - 1;
1260
1261 assert(len > 0);
1262 assert(dt_strtab_index(strtab, "") == 0);
1263
1264 dt_strtab_destroy(strtab);
1265
1266 if ((pair = dt_alloc(dtp, sizeof (*pair))) == NULL)
1267 goto err;
1268
1269 if ((pair->dlp_str = dt_alloc(dtp, len)) == NULL) {
1270 dt_free(dtp, pair);
1271 goto err;
1272 }
1273
1274 if ((pair->dlp_sym =
1275 dt_alloc(dtp, nsym * symsize)) == NULL) {
1276 dt_free(dtp, pair->dlp_str);
1277 dt_free(dtp, pair);
1278 goto err;
1279 }
1280
1281 pair->dlp_next = bufs;
1282 bufs = pair;
1283
1284 if ((data_newstr = elf_newdata(scn_str)) == NULL)
1285 goto err;
1286 data_newstr->d_size = len;
1287 data_newstr->d_buf = pair->dlp_str;
1288
1289 if ((data_newsym = elf_newdata(scn_sym)) == NULL)
1290 goto err;
1291 data_newsym->d_size = nsym * symsize;
1292 data_newsym->d_buf = pair->dlp_sym;
1293
1294 nsym += isym;
1295 } else {
1296 dt_strtab_destroy(strtab);
1297 }
1298
1299 /*
1300 * Now that the tables have been allocated, perform the
1301 * modifications described above.
1302 */
1303 for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) {
1304
1305 if (shdr_rel.sh_type == SHT_RELA) {
1306 if (gelf_getrela(data_rel, i, &rela) == NULL)
1307 continue;
1308 } else {
1309 GElf_Rel rel;
1310 if (gelf_getrel(data_rel, i, &rel) == NULL)
1311 continue;
1312 rela.r_offset = rel.r_offset;
1313 rela.r_info = rel.r_info;
1314 rela.r_addend = 0;
1315 }
1316
1317 ndx = GELF_R_SYM(rela.r_info);
1318
1319 if (gelf_getsym(data_sym, ndx, &rsym) == NULL ||
1320 rsym.st_name > data_str->d_size)
1321 goto err;
1322
1323 s = (char *)data_str->d_buf + rsym.st_name;
1324
1325 if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0)
1326 continue;
1327
1328 s += sizeof (dt_prefix) - 1;
1329
1330 /*
1331 * Check to see if this is an 'is-enabled' check as
1332 * opposed to a normal probe.
1333 */
1334 if (strncmp(s, dt_enabled,
1335 sizeof (dt_enabled) - 1) == 0) {
1336 s += sizeof (dt_enabled) - 1;
1337 eprobe = 1;
1338 *eprobesp = 1;
1339 dt_dprintf("is-enabled probe\n");
1340 } else {
1341 eprobe = 0;
1342 dt_dprintf("normal probe\n");
1343 }
1344
1345 if (*s++ != '_')
1346 goto err;
1347
1348 if ((p = strstr(s, "___")) == NULL ||
1349 p - s >= sizeof (pname))
1350 goto err;
1351
1352 bcopy(s, pname, p - s);
1353 pname[p - s] = '\0';
1354
1355 p = strhyphenate(p + 3); /* strlen("___") */
1356
1357 if (dt_symtab_lookup(data_newsym, newsym,
1358 rela.r_offset, shdr_rel.sh_info, &fsym) == 0) {
1359 if (fsym.st_name >= data_str->d_size +
1360 data_newstr->d_size)
1361 goto err;
1362 s = (char *)data_newstr->d_buf +
1363 fsym.st_name - data_str->d_size;
1364 } else if (dt_symtab_lookup(data_sym, isym,
1365 rela.r_offset, shdr_rel.sh_info, &fsym) == 0) {
1366 if (fsym.st_name >= data_str->d_size)
1367 goto err;
1368 s = (char *)data_str->d_buf + fsym.st_name;
1369 } else {
1370 goto err;
1371 }
1372
1373 assert(GELF_ST_TYPE(fsym.st_info) == STT_FUNC);
1374
1375 /*
1376 * If a NULL relocation name is passed to
1377 * dt_probe_define(), the function name is used for the
1378 * relocation. The relocation needs to use a mangled
1379 * name if the symbol is locally scoped; the function
1380 * name may need to change if we've found the global
1381 * alias for the locally scoped symbol (we prefer
1382 * global symbols to locals in dt_symtab_lookup()).
1383 */
1384 r = NULL;
1385
1386 if (GELF_ST_BIND(fsym.st_info) == STB_LOCAL) {
1387 dsym = fsym;
1388 dsym.st_name = istr;
1389 dsym.st_info = GELF_ST_INFO(STB_GLOBAL,
1390 STT_FUNC);
1391 dsym.st_other =
1392 ELF64_ST_VISIBILITY(STV_ELIMINATE);
1393 (void)gelf_update_sym(data_newsym, newsym,
1394 &dsym);
1395
1396 r = (char *)data_newstr->d_buf +
1397 (istr - data_str->d_size);
1398 istr += 1 + sprintf(r, dt_symfmt,
1399 dt_symprefix, objkey, s);
1400 isym++;
1401 newsym++;
1402 assert(isym <= nsym);
1403
1404 } else if (strncmp(s, dt_symprefix,
1405 strlen(dt_symprefix)) == 0) {
1406 r = s;
1407 if ((s = strchr(s, '.')) == NULL)
1408 goto err;
1409 s++;
1410 }
1411
1412 if ((pvp = dt_provider_lookup(dtp, pname)) == NULL) {
1413 return (dt_link_error(dtp, elf, fd, bufs,
1414 "no such provider %s", pname));
1415 }
1416
1417 if ((prp = dt_probe_lookup(pvp, p)) == NULL) {
1418 return (dt_link_error(dtp, elf, fd, bufs,
1419 "no such probe %s", p));
1420 }
1421
1422 assert(fsym.st_value <= rela.r_offset);
1423
1424 off = rela.r_offset - fsym.st_value;
1425 if (dt_modtext(dtp, data_tgt->d_buf, eprobe,
1426 &rela, &off) != 0) {
1427 goto err;
1428 }
1429
1430 if (dt_probe_define(pvp, prp, s, r, off, eprobe) != 0) {
1431 return (dt_link_error(dtp, elf, fd, bufs,
1432 "failed to allocate space for probe"));
1433 }
1434
1435 mod = 1;
1436 (void) elf_flagdata(data_tgt, ELF_C_SET, ELF_F_DIRTY);
1437
1438 /*
1439 * This symbol may already have been marked to
1440 * be ignored by another relocation referencing
1441 * the same symbol or if this object file has
1442 * already been processed by an earlier link
1443 * invocation.
1444 */
1445 if (rsym.st_shndx != SHN_SUNW_IGNORE) {
1446 rsym.st_shndx = SHN_SUNW_IGNORE;
1447 (void) gelf_update_sym(data_sym, ndx, &rsym);
1448 }
1449 }
1450 }
1451
1452 if (mod && elf_update(elf, ELF_C_WRITE) == -1)
1453 goto err;
1454
1455 (void) elf_end(elf);
1456 (void) close(fd);
1457
1458 while ((pair = bufs) != NULL) {
1459 bufs = pair->dlp_next;
1460 dt_free(dtp, pair->dlp_str);
1461 dt_free(dtp, pair->dlp_sym);
1462 dt_free(dtp, pair);
1463 }
1464
1465 return (0);
1466
1467 err:
1468 return (dt_link_error(dtp, elf, fd, bufs,
1469 "an error was encountered while processing %s", obj));
1470 }
1471
1472 int
1473 dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
1474 const char *file, int objc, char *const objv[])
1475 {
1476 char drti[PATH_MAX];
1477 dof_hdr_t *dof;
1478 int fd, status, i, cur;
1479 char *cmd, tmp;
1480 size_t len;
1481 int eprobes = 0, ret = 0;
1482
1483 /*
1484 * A NULL program indicates a special use in which we just link
1485 * together a bunch of object files specified in objv and then
1486 * unlink(2) those object files.
1487 */
1488 if (pgp == NULL) {
1489 const char *fmt = "%s -o %s -r";
1490
1491 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file) + 1;
1492
1493 for (i = 0; i < objc; i++)
1494 len += strlen(objv[i]) + 1;
1495
1496 cmd = alloca(len);
1497
1498 cur = snprintf(cmd, len, fmt, dtp->dt_ld_path, file);
1499
1500 for (i = 0; i < objc; i++)
1501 cur += snprintf(cmd + cur, len - cur, " %s", objv[i]);
1502
1503 if ((status = system(cmd)) == -1) {
1504 return (dt_link_error(dtp, NULL, -1, NULL,
1505 "failed to run %s: %s", dtp->dt_ld_path,
1506 strerror(errno)));
1507 }
1508
1509 if (WIFSIGNALED(status)) {
1510 return (dt_link_error(dtp, NULL, -1, NULL,
1511 "failed to link %s: %s failed due to signal %d",
1512 file, dtp->dt_ld_path, WTERMSIG(status)));
1513 }
1514
1515 if (WEXITSTATUS(status) != 0) {
1516 return (dt_link_error(dtp, NULL, -1, NULL,
1517 "failed to link %s: %s exited with status %d\n",
1518 file, dtp->dt_ld_path, WEXITSTATUS(status)));
1519 }
1520
1521 for (i = 0; i < objc; i++) {
1522 if (strcmp(objv[i], file) != 0)
1523 (void) unlink(objv[i]);
1524 }
1525
1526 return (0);
1527 }
1528
1529 for (i = 0; i < objc; i++) {
1530 if (process_obj(dtp, objv[i], &eprobes) != 0)
1531 return (-1); /* errno is set for us */
1532 }
1533
1534 /*
1535 * If there are is-enabled probes then we need to force use of DOF
1536 * version 2.
1537 */
1538 if (eprobes && pgp->dp_dofversion < DOF_VERSION_2)
1539 pgp->dp_dofversion = DOF_VERSION_2;
1540
1541 if ((dof = dtrace_dof_create(dtp, pgp, dflags)) == NULL)
1542 return (-1); /* errno is set for us */
1543
1544 /*
1545 * Create a temporary file and then unlink it if we're going to
1546 * combine it with drti.o later. We can still refer to it in child
1547 * processes as /dev/fd/<fd>.
1548 */
1549 if ((fd = open64(file, O_RDWR | O_CREAT | O_TRUNC, 0666)) == -1) {
1550 return (dt_link_error(dtp, NULL, -1, NULL,
1551 "failed to open %s: %s", file, strerror(errno)));
1552 }
1553
1554 /*
1555 * If -xlinktype=DOF has been selected, just write out the DOF.
1556 * Otherwise proceed to the default of generating and linking ELF.
1557 */
1558 switch (dtp->dt_linktype) {
1559 case DT_LTYP_DOF:
1560 if (dt_write(dtp, fd, dof, dof->dofh_filesz) < dof->dofh_filesz)
1561 ret = errno;
1562
1563 if (close(fd) != 0 && ret == 0)
1564 ret = errno;
1565
1566 if (ret != 0) {
1567 return (dt_link_error(dtp, NULL, -1, NULL,
1568 "failed to write %s: %s", file, strerror(ret)));
1569 }
1570
1571 return (0);
1572
1573 case DT_LTYP_ELF:
1574 break; /* fall through to the rest of dtrace_program_link() */
1575
1576 default:
1577 return (dt_link_error(dtp, NULL, -1, NULL,
1578 "invalid link type %u\n", dtp->dt_linktype));
1579 }
1580
1581
1582 if (!dtp->dt_lazyload)
1583 (void) unlink(file);
1584
1585 if (dtp->dt_oflags & DTRACE_O_LP64)
1586 status = dump_elf64(dtp, dof, fd);
1587 else
1588 status = dump_elf32(dtp, dof, fd);
1589
1590 if (status != 0 || lseek(fd, 0, SEEK_SET) != 0) {
1591 return (dt_link_error(dtp, NULL, -1, NULL,
1592 "failed to write %s: %s", file, strerror(errno)));
1593 }
1594
1595 if (!dtp->dt_lazyload) {
1596 const char *fmt = "%s -o %s -r -Blocal -Breduce /dev/fd/%d %s";
1597
1598 if (dtp->dt_oflags & DTRACE_O_LP64) {
1599 (void) snprintf(drti, sizeof (drti),
1600 "%s/64/drti.o", _dtrace_libdir);
1601 } else {
1602 (void) snprintf(drti, sizeof (drti),
1603 "%s/drti.o", _dtrace_libdir);
1604 }
1605
1606 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file, fd,
1607 drti) + 1;
1608
1609 cmd = alloca(len);
1610
1611 (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, file, fd, drti);
1612
1613 if ((status = system(cmd)) == -1) {
1614 ret = dt_link_error(dtp, NULL, -1, NULL,
1615 "failed to run %s: %s", dtp->dt_ld_path,
1616 strerror(errno));
1617 goto done;
1618 }
1619
1620 (void) close(fd); /* release temporary file */
1621
1622 if (WIFSIGNALED(status)) {
1623 ret = dt_link_error(dtp, NULL, -1, NULL,
1624 "failed to link %s: %s failed due to signal %d",
1625 file, dtp->dt_ld_path, WTERMSIG(status));
1626 goto done;
1627 }
1628
1629 if (WEXITSTATUS(status) != 0) {
1630 ret = dt_link_error(dtp, NULL, -1, NULL,
1631 "failed to link %s: %s exited with status %d\n",
1632 file, dtp->dt_ld_path, WEXITSTATUS(status));
1633 goto done;
1634 }
1635 } else {
1636 (void) close(fd);
1637 }
1638
1639 done:
1640 dtrace_dof_destroy(dtp, dof);
1641 return (ret);
1642 }