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