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 * Copyright 2016 Mark Johnston.
26 */
27
28 #define ELF_TARGET_ALL
29 #include <elf.h>
30
31 #include <sys/types.h>
32 #include <sys/sysmacros.h>
33
34 #include <unistd.h>
35 #include <strings.h>
36 #include <alloca.h>
37 #include <limits.h>
38 #include <stddef.h>
39 #include <stdlib.h>
40 #include <stdio.h>
41 #include <fcntl.h>
42 #include <errno.h>
43 #include <wait.h>
44 #include <assert.h>
45 #include <sys/ipc.h>
46
47 #include <dt_impl.h>
48 #include <dt_provider.h>
49 #include <dt_program.h>
50 #include <dt_string.h>
51
52 #define ESHDR_NULL 0
53 #define ESHDR_SHSTRTAB 1
54 #define ESHDR_DOF 2
55 #define ESHDR_STRTAB 3
56 #define ESHDR_SYMTAB 4
57 #define ESHDR_REL 5
58 #define ESHDR_NUM 6
59
60 #define PWRITE_SCN(index, data) \
61 (lseek64(fd, (off64_t)elf_file.shdr[(index)].sh_offset, SEEK_SET) != \
62 (off64_t)elf_file.shdr[(index)].sh_offset || \
63 dt_write(dtp, fd, (data), elf_file.shdr[(index)].sh_size) != \
64 elf_file.shdr[(index)].sh_size)
65
66 static const char DTRACE_SHSTRTAB32[] = "\0"
67 ".shstrtab\0" /* 1 */
68 ".SUNW_dof\0" /* 11 */
69 ".strtab\0" /* 21 */
70 ".symtab\0" /* 29 */
71 #ifdef __sparc
72 ".rela.SUNW_dof"; /* 37 */
73 #else
74 ".rel.SUNW_dof"; /* 37 */
75 #endif
76
77 static const char DTRACE_SHSTRTAB64[] = "\0"
78 ".shstrtab\0" /* 1 */
79 ".SUNW_dof\0" /* 11 */
80 ".strtab\0" /* 21 */
81 ".symtab\0" /* 29 */
82 ".rela.SUNW_dof"; /* 37 */
83
84 static const char DOFSTR[] = "__SUNW_dof";
85 static const char DOFLAZYSTR[] = "___SUNW_dof";
86
87 typedef struct dt_link_pair {
88 struct dt_link_pair *dlp_next; /* next pair in linked list */
89 void *dlp_str; /* buffer for string table */
90 void *dlp_sym; /* buffer for symbol table */
91 } dt_link_pair_t;
92
93 typedef struct dof_elf32 {
94 uint32_t de_nrel; /* relocation count */
95 #ifdef __sparc
96 Elf32_Rela *de_rel; /* array of relocations for sparc */
97 #else
98 Elf32_Rel *de_rel; /* array of relocations for x86 */
99 #endif
100 uint32_t de_nsym; /* symbol count */
101 Elf32_Sym *de_sym; /* array of symbols */
102 uint32_t de_strlen; /* size of of string table */
103 char *de_strtab; /* string table */
104 uint32_t de_global; /* index of the first global symbol */
105 } dof_elf32_t;
106
107 static int
prepare_elf32(dtrace_hdl_t * dtp,const dof_hdr_t * dof,dof_elf32_t * dep)108 prepare_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf32_t *dep)
109 {
110 dof_sec_t *dofs, *s;
111 dof_relohdr_t *dofrh;
112 dof_relodesc_t *dofr;
113 char *strtab;
114 int i, j, nrel;
115 size_t strtabsz = 1;
116 uint32_t count = 0;
117 size_t base;
118 Elf32_Sym *sym;
119 #ifdef __sparc
120 Elf32_Rela *rel;
121 #else
122 Elf32_Rel *rel;
123 #endif
124
125 /*LINTED*/
126 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff);
127
128 /*
129 * First compute the size of the string table and the number of
130 * relocations present in the DOF.
131 */
132 for (i = 0; i < dof->dofh_secnum; i++) {
133 if (dofs[i].dofs_type != DOF_SECT_URELHDR)
134 continue;
135
136 /*LINTED*/
137 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
138
139 s = &dofs[dofrh->dofr_strtab];
140 strtab = (char *)dof + s->dofs_offset;
141 assert(strtab[0] == '\0');
142 strtabsz += s->dofs_size - 1;
143
144 s = &dofs[dofrh->dofr_relsec];
145 /*LINTED*/
146 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
147 count += s->dofs_size / s->dofs_entsize;
148 }
149
150 dep->de_strlen = strtabsz;
151 dep->de_nrel = count;
152 dep->de_nsym = count + 1; /* the first symbol is always null */
153
154 if (dtp->dt_lazyload) {
155 dep->de_strlen += sizeof (DOFLAZYSTR);
156 dep->de_nsym++;
157 } else {
158 dep->de_strlen += sizeof (DOFSTR);
159 dep->de_nsym++;
160 }
161
162 if ((dep->de_rel = calloc(dep->de_nrel,
163 sizeof (dep->de_rel[0]))) == NULL) {
164 return (dt_set_errno(dtp, EDT_NOMEM));
165 }
166
167 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf32_Sym))) == NULL) {
168 free(dep->de_rel);
169 return (dt_set_errno(dtp, EDT_NOMEM));
170 }
171
172 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) {
173 free(dep->de_rel);
174 free(dep->de_sym);
175 return (dt_set_errno(dtp, EDT_NOMEM));
176 }
177
178 count = 0;
179 strtabsz = 1;
180 dep->de_strtab[0] = '\0';
181 rel = dep->de_rel;
182 sym = dep->de_sym;
183 dep->de_global = 1;
184
185 /*
186 * The first symbol table entry must be zeroed and is always ignored.
187 */
188 bzero(sym, sizeof (Elf32_Sym));
189 sym++;
190
191 /*
192 * Take a second pass through the DOF sections filling in the
193 * memory we allocated.
194 */
195 for (i = 0; i < dof->dofh_secnum; i++) {
196 if (dofs[i].dofs_type != DOF_SECT_URELHDR)
197 continue;
198
199 /*LINTED*/
200 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
201
202 s = &dofs[dofrh->dofr_strtab];
203 strtab = (char *)dof + s->dofs_offset;
204 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size);
205 base = strtabsz;
206 strtabsz += s->dofs_size - 1;
207
208 s = &dofs[dofrh->dofr_relsec];
209 /*LINTED*/
210 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
211 nrel = s->dofs_size / s->dofs_entsize;
212
213 s = &dofs[dofrh->dofr_tgtsec];
214
215 for (j = 0; j < nrel; j++) {
216 #if defined(__i386) || defined(__amd64)
217 rel->r_offset = s->dofs_offset +
218 dofr[j].dofr_offset;
219 rel->r_info = ELF32_R_INFO(count + dep->de_global,
220 R_386_32);
221 #elif defined(__sparc)
222 /*
223 * Add 4 bytes to hit the low half of this 64-bit
224 * big-endian address.
225 */
226 rel->r_offset = s->dofs_offset +
227 dofr[j].dofr_offset + 4;
228 rel->r_info = ELF32_R_INFO(count + dep->de_global,
229 R_SPARC_32);
230 #else
231 #error unknown ISA
232 #endif
233
234 sym->st_name = base + dofr[j].dofr_name - 1;
235 sym->st_value = 0;
236 sym->st_size = 0;
237 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_FUNC);
238 sym->st_other = 0;
239 sym->st_shndx = SHN_UNDEF;
240
241 rel++;
242 sym++;
243 count++;
244 }
245 }
246
247 /*
248 * Add a symbol for the DOF itself. We use a different symbol for
249 * lazily and actively loaded DOF to make them easy to distinguish.
250 */
251 sym->st_name = strtabsz;
252 sym->st_value = 0;
253 sym->st_size = dof->dofh_filesz;
254 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_OBJECT);
255 sym->st_other = 0;
256 sym->st_shndx = ESHDR_DOF;
257 sym++;
258
259 if (dtp->dt_lazyload) {
260 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz,
261 sizeof (DOFLAZYSTR));
262 strtabsz += sizeof (DOFLAZYSTR);
263 } else {
264 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR));
265 strtabsz += sizeof (DOFSTR);
266 }
267
268 assert(count == dep->de_nrel);
269 assert(strtabsz == dep->de_strlen);
270
271 return (0);
272 }
273
274
275 typedef struct dof_elf64 {
276 uint32_t de_nrel;
277 Elf64_Rela *de_rel;
278 uint32_t de_nsym;
279 Elf64_Sym *de_sym;
280
281 uint32_t de_strlen;
282 char *de_strtab;
283
284 uint32_t de_global;
285 } dof_elf64_t;
286
287 static int
prepare_elf64(dtrace_hdl_t * dtp,const dof_hdr_t * dof,dof_elf64_t * dep)288 prepare_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf64_t *dep)
289 {
290 dof_sec_t *dofs, *s;
291 dof_relohdr_t *dofrh;
292 dof_relodesc_t *dofr;
293 char *strtab;
294 int i, j, nrel;
295 size_t strtabsz = 1;
296 uint32_t count = 0;
297 size_t base;
298 Elf64_Sym *sym;
299 Elf64_Rela *rel;
300
301 /*LINTED*/
302 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff);
303
304 /*
305 * First compute the size of the string table and the number of
306 * relocations present in the DOF.
307 */
308 for (i = 0; i < dof->dofh_secnum; i++) {
309 if (dofs[i].dofs_type != DOF_SECT_URELHDR)
310 continue;
311
312 /*LINTED*/
313 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
314
315 s = &dofs[dofrh->dofr_strtab];
316 strtab = (char *)dof + s->dofs_offset;
317 assert(strtab[0] == '\0');
318 strtabsz += s->dofs_size - 1;
319
320 s = &dofs[dofrh->dofr_relsec];
321 /*LINTED*/
322 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
323 count += s->dofs_size / s->dofs_entsize;
324 }
325
326 dep->de_strlen = strtabsz;
327 dep->de_nrel = count;
328 dep->de_nsym = count + 1; /* the first symbol is always null */
329
330 if (dtp->dt_lazyload) {
331 dep->de_strlen += sizeof (DOFLAZYSTR);
332 dep->de_nsym++;
333 } else {
334 dep->de_strlen += sizeof (DOFSTR);
335 dep->de_nsym++;
336 }
337
338 if ((dep->de_rel = calloc(dep->de_nrel,
339 sizeof (dep->de_rel[0]))) == NULL) {
340 return (dt_set_errno(dtp, EDT_NOMEM));
341 }
342
343 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf64_Sym))) == NULL) {
344 free(dep->de_rel);
345 return (dt_set_errno(dtp, EDT_NOMEM));
346 }
347
348 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) {
349 free(dep->de_rel);
350 free(dep->de_sym);
351 return (dt_set_errno(dtp, EDT_NOMEM));
352 }
353
354 count = 0;
355 strtabsz = 1;
356 dep->de_strtab[0] = '\0';
357 rel = dep->de_rel;
358 sym = dep->de_sym;
359 dep->de_global = 1;
360
361 /*
362 * The first symbol table entry must be zeroed and is always ignored.
363 */
364 bzero(sym, sizeof (Elf64_Sym));
365 sym++;
366
367 /*
368 * Take a second pass through the DOF sections filling in the
369 * memory we allocated.
370 */
371 for (i = 0; i < dof->dofh_secnum; i++) {
372 if (dofs[i].dofs_type != DOF_SECT_URELHDR)
373 continue;
374
375 /*LINTED*/
376 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
377
378 s = &dofs[dofrh->dofr_strtab];
379 strtab = (char *)dof + s->dofs_offset;
380 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size);
381 base = strtabsz;
382 strtabsz += s->dofs_size - 1;
383
384 s = &dofs[dofrh->dofr_relsec];
385 /*LINTED*/
386 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
387 nrel = s->dofs_size / s->dofs_entsize;
388
389 s = &dofs[dofrh->dofr_tgtsec];
390
391 for (j = 0; j < nrel; j++) {
392 #if defined(__i386) || defined(__amd64)
393 rel->r_offset = s->dofs_offset +
394 dofr[j].dofr_offset;
395 rel->r_info = ELF64_R_INFO(count + dep->de_global,
396 R_AMD64_64);
397 #elif defined(__sparc)
398 rel->r_offset = s->dofs_offset +
399 dofr[j].dofr_offset;
400 rel->r_info = ELF64_R_INFO(count + dep->de_global,
401 R_SPARC_64);
402 #else
403 #error unknown ISA
404 #endif
405
406 sym->st_name = base + dofr[j].dofr_name - 1;
407 sym->st_value = 0;
408 sym->st_size = 0;
409 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_FUNC);
410 sym->st_other = 0;
411 sym->st_shndx = SHN_UNDEF;
412
413 rel++;
414 sym++;
415 count++;
416 }
417 }
418
419 /*
420 * Add a symbol for the DOF itself. We use a different symbol for
421 * lazily and actively loaded DOF to make them easy to distinguish.
422 */
423 sym->st_name = strtabsz;
424 sym->st_value = 0;
425 sym->st_size = dof->dofh_filesz;
426 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_OBJECT);
427 sym->st_other = 0;
428 sym->st_shndx = ESHDR_DOF;
429 sym++;
430
431 if (dtp->dt_lazyload) {
432 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz,
433 sizeof (DOFLAZYSTR));
434 strtabsz += sizeof (DOFLAZYSTR);
435 } else {
436 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR));
437 strtabsz += sizeof (DOFSTR);
438 }
439
440 assert(count == dep->de_nrel);
441 assert(strtabsz == dep->de_strlen);
442
443 return (0);
444 }
445
446 /*
447 * Write out an ELF32 file prologue consisting of a header, section headers,
448 * and a section header string table. The DOF data will follow this prologue
449 * and complete the contents of the given ELF file.
450 */
451 static int
dump_elf32(dtrace_hdl_t * dtp,const dof_hdr_t * dof,int fd)452 dump_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd)
453 {
454 struct {
455 Elf32_Ehdr ehdr;
456 Elf32_Shdr shdr[ESHDR_NUM];
457 } elf_file;
458
459 Elf32_Shdr *shp;
460 Elf32_Off off;
461 dof_elf32_t de;
462 int ret = 0;
463 uint_t nshdr;
464
465 if (prepare_elf32(dtp, dof, &de) != 0)
466 return (-1); /* errno is set for us */
467
468 /*
469 * If there are no relocations, we only need enough sections for
470 * the shstrtab and the DOF.
471 */
472 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM;
473
474 bzero(&elf_file, sizeof (elf_file));
475
476 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0;
477 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1;
478 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2;
479 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3;
480 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT;
481 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS32;
482 #if defined(_BIG_ENDIAN)
483 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB;
484 #elif defined(_LITTLE_ENDIAN)
485 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
486 #endif
487 elf_file.ehdr.e_type = ET_REL;
488 #if defined(__sparc)
489 elf_file.ehdr.e_machine = EM_SPARC;
490 #elif defined(__i386) || defined(__amd64)
491 elf_file.ehdr.e_machine = EM_386;
492 #endif
493 elf_file.ehdr.e_version = EV_CURRENT;
494 elf_file.ehdr.e_shoff = sizeof (Elf32_Ehdr);
495 elf_file.ehdr.e_ehsize = sizeof (Elf32_Ehdr);
496 elf_file.ehdr.e_phentsize = sizeof (Elf32_Phdr);
497 elf_file.ehdr.e_shentsize = sizeof (Elf32_Shdr);
498 elf_file.ehdr.e_shnum = nshdr;
499 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB;
500 off = sizeof (elf_file) + nshdr * sizeof (Elf32_Shdr);
501
502 shp = &elf_file.shdr[ESHDR_SHSTRTAB];
503 shp->sh_name = 1; /* DTRACE_SHSTRTAB32[1] = ".shstrtab" */
504 shp->sh_type = SHT_STRTAB;
505 shp->sh_offset = off;
506 shp->sh_size = sizeof (DTRACE_SHSTRTAB32);
507 shp->sh_addralign = sizeof (char);
508 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
509
510 shp = &elf_file.shdr[ESHDR_DOF];
511 shp->sh_name = 11; /* DTRACE_SHSTRTAB32[11] = ".SUNW_dof" */
512 shp->sh_flags = SHF_ALLOC;
513 shp->sh_type = SHT_SUNW_dof;
514 shp->sh_offset = off;
515 shp->sh_size = dof->dofh_filesz;
516 shp->sh_addralign = 8;
517 off = shp->sh_offset + shp->sh_size;
518
519 shp = &elf_file.shdr[ESHDR_STRTAB];
520 shp->sh_name = 21; /* DTRACE_SHSTRTAB32[21] = ".strtab" */
521 shp->sh_flags = SHF_ALLOC;
522 shp->sh_type = SHT_STRTAB;
523 shp->sh_offset = off;
524 shp->sh_size = de.de_strlen;
525 shp->sh_addralign = sizeof (char);
526 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4);
527
528 shp = &elf_file.shdr[ESHDR_SYMTAB];
529 shp->sh_name = 29; /* DTRACE_SHSTRTAB32[29] = ".symtab" */
530 shp->sh_flags = SHF_ALLOC;
531 shp->sh_type = SHT_SYMTAB;
532 shp->sh_entsize = sizeof (Elf32_Sym);
533 shp->sh_link = ESHDR_STRTAB;
534 shp->sh_offset = off;
535 shp->sh_info = de.de_global;
536 shp->sh_size = de.de_nsym * sizeof (Elf32_Sym);
537 shp->sh_addralign = 4;
538 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4);
539
540 if (de.de_nrel == 0) {
541 if (dt_write(dtp, fd, &elf_file,
542 sizeof (elf_file)) != sizeof (elf_file) ||
543 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) ||
544 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
545 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
546 PWRITE_SCN(ESHDR_DOF, dof)) {
547 ret = dt_set_errno(dtp, errno);
548 }
549 } else {
550 shp = &elf_file.shdr[ESHDR_REL];
551 shp->sh_name = 37; /* DTRACE_SHSTRTAB32[37] = ".rel.SUNW_dof" */
552 shp->sh_flags = SHF_ALLOC;
553 #ifdef __sparc
554 shp->sh_type = SHT_RELA;
555 #else
556 shp->sh_type = SHT_REL;
557 #endif
558 shp->sh_entsize = sizeof (de.de_rel[0]);
559 shp->sh_link = ESHDR_SYMTAB;
560 shp->sh_info = ESHDR_DOF;
561 shp->sh_offset = off;
562 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]);
563 shp->sh_addralign = 4;
564
565 if (dt_write(dtp, fd, &elf_file,
566 sizeof (elf_file)) != sizeof (elf_file) ||
567 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) ||
568 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
569 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
570 PWRITE_SCN(ESHDR_REL, de.de_rel) ||
571 PWRITE_SCN(ESHDR_DOF, dof)) {
572 ret = dt_set_errno(dtp, errno);
573 }
574 }
575
576 free(de.de_strtab);
577 free(de.de_sym);
578 free(de.de_rel);
579
580 return (ret);
581 }
582
583 /*
584 * Write out an ELF64 file prologue consisting of a header, section headers,
585 * and a section header string table. The DOF data will follow this prologue
586 * and complete the contents of the given ELF file.
587 */
588 static int
dump_elf64(dtrace_hdl_t * dtp,const dof_hdr_t * dof,int fd)589 dump_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd)
590 {
591 struct {
592 Elf64_Ehdr ehdr;
593 Elf64_Shdr shdr[ESHDR_NUM];
594 } elf_file;
595
596 Elf64_Shdr *shp;
597 Elf64_Off off;
598 dof_elf64_t de;
599 int ret = 0;
600 uint_t nshdr;
601
602 if (prepare_elf64(dtp, dof, &de) != 0)
603 return (-1); /* errno is set for us */
604
605 /*
606 * If there are no relocations, we only need enough sections for
607 * the shstrtab and the DOF.
608 */
609 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM;
610
611 bzero(&elf_file, sizeof (elf_file));
612
613 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0;
614 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1;
615 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2;
616 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3;
617 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT;
618 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS64;
619 #if defined(_BIG_ENDIAN)
620 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB;
621 #elif defined(_LITTLE_ENDIAN)
622 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
623 #endif
624 elf_file.ehdr.e_type = ET_REL;
625 #if defined(__sparc)
626 elf_file.ehdr.e_machine = EM_SPARCV9;
627 #elif defined(__i386) || defined(__amd64)
628 elf_file.ehdr.e_machine = EM_AMD64;
629 #endif
630 elf_file.ehdr.e_version = EV_CURRENT;
631 elf_file.ehdr.e_shoff = sizeof (Elf64_Ehdr);
632 elf_file.ehdr.e_ehsize = sizeof (Elf64_Ehdr);
633 elf_file.ehdr.e_phentsize = sizeof (Elf64_Phdr);
634 elf_file.ehdr.e_shentsize = sizeof (Elf64_Shdr);
635 elf_file.ehdr.e_shnum = nshdr;
636 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB;
637 off = sizeof (elf_file) + nshdr * sizeof (Elf64_Shdr);
638
639 shp = &elf_file.shdr[ESHDR_SHSTRTAB];
640 shp->sh_name = 1; /* DTRACE_SHSTRTAB64[1] = ".shstrtab" */
641 shp->sh_type = SHT_STRTAB;
642 shp->sh_offset = off;
643 shp->sh_size = sizeof (DTRACE_SHSTRTAB64);
644 shp->sh_addralign = sizeof (char);
645 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
646
647 shp = &elf_file.shdr[ESHDR_DOF];
648 shp->sh_name = 11; /* DTRACE_SHSTRTAB64[11] = ".SUNW_dof" */
649 shp->sh_flags = SHF_ALLOC;
650 shp->sh_type = SHT_SUNW_dof;
651 shp->sh_offset = off;
652 shp->sh_size = dof->dofh_filesz;
653 shp->sh_addralign = 8;
654 off = shp->sh_offset + shp->sh_size;
655
656 shp = &elf_file.shdr[ESHDR_STRTAB];
657 shp->sh_name = 21; /* DTRACE_SHSTRTAB64[21] = ".strtab" */
658 shp->sh_flags = SHF_ALLOC;
659 shp->sh_type = SHT_STRTAB;
660 shp->sh_offset = off;
661 shp->sh_size = de.de_strlen;
662 shp->sh_addralign = sizeof (char);
663 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
664
665 shp = &elf_file.shdr[ESHDR_SYMTAB];
666 shp->sh_name = 29; /* DTRACE_SHSTRTAB64[29] = ".symtab" */
667 shp->sh_flags = SHF_ALLOC;
668 shp->sh_type = SHT_SYMTAB;
669 shp->sh_entsize = sizeof (Elf64_Sym);
670 shp->sh_link = ESHDR_STRTAB;
671 shp->sh_offset = off;
672 shp->sh_info = de.de_global;
673 shp->sh_size = de.de_nsym * sizeof (Elf64_Sym);
674 shp->sh_addralign = 8;
675 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
676
677 if (de.de_nrel == 0) {
678 if (dt_write(dtp, fd, &elf_file,
679 sizeof (elf_file)) != sizeof (elf_file) ||
680 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) ||
681 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
682 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
683 PWRITE_SCN(ESHDR_DOF, dof)) {
684 ret = dt_set_errno(dtp, errno);
685 }
686 } else {
687 shp = &elf_file.shdr[ESHDR_REL];
688 shp->sh_name = 37; /* DTRACE_SHSTRTAB64[37] = ".rel.SUNW_dof" */
689 shp->sh_flags = SHF_ALLOC;
690 shp->sh_type = SHT_RELA;
691 shp->sh_entsize = sizeof (de.de_rel[0]);
692 shp->sh_link = ESHDR_SYMTAB;
693 shp->sh_info = ESHDR_DOF;
694 shp->sh_offset = off;
695 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]);
696 shp->sh_addralign = 8;
697
698 if (dt_write(dtp, fd, &elf_file,
699 sizeof (elf_file)) != sizeof (elf_file) ||
700 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) ||
701 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
702 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
703 PWRITE_SCN(ESHDR_REL, de.de_rel) ||
704 PWRITE_SCN(ESHDR_DOF, dof)) {
705 ret = dt_set_errno(dtp, errno);
706 }
707 }
708
709 free(de.de_strtab);
710 free(de.de_sym);
711 free(de.de_rel);
712
713 return (ret);
714 }
715
716 static int
dt_symtab_lookup(Elf_Data * data_sym,int nsym,uintptr_t addr,uint_t shn,GElf_Sym * sym)717 dt_symtab_lookup(Elf_Data *data_sym, int nsym, uintptr_t addr, uint_t shn,
718 GElf_Sym *sym)
719 {
720 int i, ret = -1;
721 GElf_Sym s;
722
723 for (i = 0; i < nsym && gelf_getsym(data_sym, i, sym) != NULL; i++) {
724 if (GELF_ST_TYPE(sym->st_info) == STT_FUNC &&
725 shn == sym->st_shndx &&
726 sym->st_value <= addr &&
727 addr < sym->st_value + sym->st_size) {
728 if (GELF_ST_BIND(sym->st_info) == STB_GLOBAL)
729 return (0);
730
731 ret = 0;
732 s = *sym;
733 }
734 }
735
736 if (ret == 0)
737 *sym = s;
738 return (ret);
739 }
740
741 #if defined(__sparc)
742
743 #define DT_OP_RET 0x81c7e008
744 #define DT_OP_NOP 0x01000000
745 #define DT_OP_CALL 0x40000000
746 #define DT_OP_CLR_O0 0x90102000
747
748 #define DT_IS_MOV_O7(inst) (((inst) & 0xffffe000) == 0x9e100000)
749 #define DT_IS_RESTORE(inst) (((inst) & 0xc1f80000) == 0x81e80000)
750 #define DT_IS_RETL(inst) (((inst) & 0xfff83fff) == 0x81c02008)
751
752 #define DT_RS2(inst) ((inst) & 0x1f)
753 #define DT_MAKE_RETL(reg) (0x81c02008 | ((reg) << 14))
754
755 /*ARGSUSED*/
756 static int
dt_modtext(dtrace_hdl_t * dtp,char * p,int isenabled,GElf_Rela * rela,uint32_t * off)757 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela,
758 uint32_t *off)
759 {
760 uint32_t *ip;
761
762 if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0)
763 return (-1);
764
765 /*LINTED*/
766 ip = (uint32_t *)(p + rela->r_offset);
767
768 /*
769 * We only know about some specific relocation types.
770 */
771 if (GELF_R_TYPE(rela->r_info) != R_SPARC_WDISP30 &&
772 GELF_R_TYPE(rela->r_info) != R_SPARC_WPLT30)
773 return (-1);
774
775 /*
776 * We may have already processed this object file in an earlier linker
777 * invocation. Check to see if the present instruction sequence matches
778 * the one we would install below.
779 */
780 if (isenabled) {
781 if (ip[0] == DT_OP_NOP) {
782 (*off) += sizeof (ip[0]);
783 return (0);
784 }
785 } else {
786 if (DT_IS_RESTORE(ip[1])) {
787 if (ip[0] == DT_OP_RET) {
788 (*off) += sizeof (ip[0]);
789 return (0);
790 }
791 } else if (DT_IS_MOV_O7(ip[1])) {
792 if (DT_IS_RETL(ip[0]))
793 return (0);
794 } else {
795 if (ip[0] == DT_OP_NOP) {
796 (*off) += sizeof (ip[0]);
797 return (0);
798 }
799 }
800 }
801
802 /*
803 * We only expect call instructions with a displacement of 0.
804 */
805 if (ip[0] != DT_OP_CALL) {
806 dt_dprintf("found %x instead of a call instruction at %llx\n",
807 ip[0], (u_longlong_t)rela->r_offset);
808 return (-1);
809 }
810
811 if (isenabled) {
812 /*
813 * It would necessarily indicate incorrect usage if an is-
814 * enabled probe were tail-called so flag that as an error.
815 * It's also potentially (very) tricky to handle gracefully,
816 * but could be done if this were a desired use scenario.
817 */
818 if (DT_IS_RESTORE(ip[1]) || DT_IS_MOV_O7(ip[1])) {
819 dt_dprintf("tail call to is-enabled probe at %llx\n",
820 (u_longlong_t)rela->r_offset);
821 return (-1);
822 }
823
824
825 /*
826 * On SPARC, we take advantage of the fact that the first
827 * argument shares the same register as for the return value.
828 * The macro handles the work of zeroing that register so we
829 * don't need to do anything special here. We instrument the
830 * instruction in the delay slot as we'll need to modify the
831 * return register after that instruction has been emulated.
832 */
833 ip[0] = DT_OP_NOP;
834 (*off) += sizeof (ip[0]);
835 } else {
836 /*
837 * If the call is followed by a restore, it's a tail call so
838 * change the call to a ret. If the call if followed by a mov
839 * of a register into %o7, it's a tail call in leaf context
840 * so change the call to a retl-like instruction that returns
841 * to that register value + 8 (rather than the typical %o7 +
842 * 8); the delay slot instruction is left, but should have no
843 * effect. Otherwise we change the call to be a nop. We
844 * identify the subsequent instruction as the probe point in
845 * all but the leaf tail-call case to ensure that arguments to
846 * the probe are complete and consistent. An astute, though
847 * largely hypothetical, observer would note that there is the
848 * possibility of a false-positive probe firing if the function
849 * contained a branch to the instruction in the delay slot of
850 * the call. Fixing this would require significant in-kernel
851 * modifications, and isn't worth doing until we see it in the
852 * wild.
853 */
854 if (DT_IS_RESTORE(ip[1])) {
855 ip[0] = DT_OP_RET;
856 (*off) += sizeof (ip[0]);
857 } else if (DT_IS_MOV_O7(ip[1])) {
858 ip[0] = DT_MAKE_RETL(DT_RS2(ip[1]));
859 } else {
860 ip[0] = DT_OP_NOP;
861 (*off) += sizeof (ip[0]);
862 }
863 }
864
865 return (0);
866 }
867
868 #elif defined(__i386) || defined(__amd64)
869
870 #define DT_OP_NOP 0x90
871 #define DT_OP_RET 0xc3
872 #define DT_OP_CALL 0xe8
873 #define DT_OP_JMP32 0xe9
874 #define DT_OP_REX_RAX 0x48
875 #define DT_OP_XOR_EAX_0 0x33
876 #define DT_OP_XOR_EAX_1 0xc0
877
878 static int
dt_modtext(dtrace_hdl_t * dtp,char * p,int isenabled,GElf_Rela * rela,uint32_t * off)879 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela,
880 uint32_t *off)
881 {
882 uint8_t *ip = (uint8_t *)(p + rela->r_offset - 1);
883 uint8_t ret;
884
885 /*
886 * On x86, the first byte of the instruction is the call opcode and
887 * the next four bytes are the 32-bit address; the relocation is for
888 * the address operand. We back up the offset to the first byte of
889 * the instruction. For is-enabled probes, we later advance the offset
890 * so that it hits the first nop in the instruction sequence.
891 */
892 (*off) -= 1;
893
894 /*
895 * We only know about some specific relocation types. Luckily
896 * these types have the same values on both 32-bit and 64-bit
897 * x86 architectures.
898 */
899 if (GELF_R_TYPE(rela->r_info) != R_386_PC32 &&
900 GELF_R_TYPE(rela->r_info) != R_386_PLT32)
901 return (-1);
902
903 /*
904 * We may have already processed this object file in an earlier linker
905 * invocation. Check to see if the present instruction sequence matches
906 * the one we would install. For is-enabled probes, we advance the
907 * offset to the first nop instruction in the sequence to match the
908 * text modification code below.
909 */
910 if (!isenabled) {
911 if ((ip[0] == DT_OP_NOP || ip[0] == DT_OP_RET) &&
912 ip[1] == DT_OP_NOP && ip[2] == DT_OP_NOP &&
913 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP)
914 return (0);
915 } else if (dtp->dt_oflags & DTRACE_O_LP64) {
916 if (ip[0] == DT_OP_REX_RAX &&
917 ip[1] == DT_OP_XOR_EAX_0 && ip[2] == DT_OP_XOR_EAX_1 &&
918 (ip[3] == DT_OP_NOP || ip[3] == DT_OP_RET) &&
919 ip[4] == DT_OP_NOP) {
920 (*off) += 3;
921 return (0);
922 }
923 } else {
924 if (ip[0] == DT_OP_XOR_EAX_0 && ip[1] == DT_OP_XOR_EAX_1 &&
925 (ip[2] == DT_OP_NOP || ip[2] == DT_OP_RET) &&
926 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) {
927 (*off) += 2;
928 return (0);
929 }
930 }
931
932 /*
933 * We expect either a call instrution with a 32-bit displacement or a
934 * jmp instruction with a 32-bit displacement acting as a tail-call.
935 */
936 if (ip[0] != DT_OP_CALL && ip[0] != DT_OP_JMP32) {
937 dt_dprintf("found %x instead of a call or jmp instruction at "
938 "%llx\n", ip[0], (u_longlong_t)rela->r_offset);
939 return (-1);
940 }
941
942 ret = (ip[0] == DT_OP_JMP32) ? DT_OP_RET : DT_OP_NOP;
943
944 /*
945 * Establish the instruction sequence -- all nops for probes, and an
946 * instruction to clear the return value register (%eax/%rax) followed
947 * by nops for is-enabled probes. For is-enabled probes, we advance
948 * the offset to the first nop. This isn't stricly necessary but makes
949 * for more readable disassembly when the probe is enabled.
950 */
951 if (!isenabled) {
952 ip[0] = ret;
953 ip[1] = DT_OP_NOP;
954 ip[2] = DT_OP_NOP;
955 ip[3] = DT_OP_NOP;
956 ip[4] = DT_OP_NOP;
957 } else if (dtp->dt_oflags & DTRACE_O_LP64) {
958 ip[0] = DT_OP_REX_RAX;
959 ip[1] = DT_OP_XOR_EAX_0;
960 ip[2] = DT_OP_XOR_EAX_1;
961 ip[3] = ret;
962 ip[4] = DT_OP_NOP;
963 (*off) += 3;
964 } else {
965 ip[0] = DT_OP_XOR_EAX_0;
966 ip[1] = DT_OP_XOR_EAX_1;
967 ip[2] = ret;
968 ip[3] = DT_OP_NOP;
969 ip[4] = DT_OP_NOP;
970 (*off) += 2;
971 }
972
973 return (0);
974 }
975
976 #else
977 #error unknown ISA
978 #endif
979
980 /*PRINTFLIKE5*/
981 static int
dt_link_error(dtrace_hdl_t * dtp,Elf * elf,int fd,dt_link_pair_t * bufs,const char * format,...)982 dt_link_error(dtrace_hdl_t *dtp, Elf *elf, int fd, dt_link_pair_t *bufs,
983 const char *format, ...)
984 {
985 va_list ap;
986 dt_link_pair_t *pair;
987
988 va_start(ap, format);
989 dt_set_errmsg(dtp, NULL, NULL, NULL, 0, format, ap);
990 va_end(ap);
991
992 if (elf != NULL)
993 (void) elf_end(elf);
994
995 if (fd >= 0)
996 (void) close(fd);
997
998 while ((pair = bufs) != NULL) {
999 bufs = pair->dlp_next;
1000 dt_free(dtp, pair->dlp_str);
1001 dt_free(dtp, pair->dlp_sym);
1002 dt_free(dtp, pair);
1003 }
1004
1005 return (dt_set_errno(dtp, EDT_COMPILER));
1006 }
1007
1008 static int
process_obj(dtrace_hdl_t * dtp,const char * obj,int * eprobesp)1009 process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp)
1010 {
1011 static const char dt_prefix[] = "__dtrace";
1012 static const char dt_enabled[] = "enabled";
1013 static const char dt_symprefix[] = "$dtrace";
1014 static const char dt_symfmt[] = "%s%d.%s";
1015 char probename[DTRACE_NAMELEN];
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 if (dt_symtab_lookup(data_sym, isym, rela.r_offset,
1359 shdr_rel.sh_info, &fsym) != 0)
1360 goto err;
1361
1362 if (fsym.st_name > data_str->d_size)
1363 goto err;
1364
1365 assert(GELF_ST_TYPE(fsym.st_info) == STT_FUNC);
1366
1367 /*
1368 * If a NULL relocation name is passed to
1369 * dt_probe_define(), the function name is used for the
1370 * relocation. The relocation needs to use a mangled
1371 * name if the symbol is locally scoped; the function
1372 * name may need to change if we've found the global
1373 * alias for the locally scoped symbol (we prefer
1374 * global symbols to locals in dt_symtab_lookup()).
1375 */
1376 s = (char *)data_str->d_buf + fsym.st_name;
1377 r = NULL;
1378
1379 if (GELF_ST_BIND(fsym.st_info) == STB_LOCAL) {
1380 dsym = fsym;
1381 dsym.st_name = istr;
1382 dsym.st_info = GELF_ST_INFO(STB_GLOBAL,
1383 STT_FUNC);
1384 dsym.st_other =
1385 ELF64_ST_VISIBILITY(STV_ELIMINATE);
1386 (void) gelf_update_sym(data_sym, isym, &dsym);
1387
1388 r = (char *)data_str->d_buf + istr;
1389 istr += 1 + sprintf(r, dt_symfmt,
1390 dt_symprefix, objkey, s);
1391 isym++;
1392 assert(isym <= nsym);
1393
1394 } else if (strncmp(s, dt_symprefix,
1395 strlen(dt_symprefix)) == 0) {
1396 r = s;
1397 if ((s = strchr(s, '.')) == NULL)
1398 goto err;
1399 s++;
1400 }
1401
1402 if ((pvp = dt_provider_lookup(dtp, pname)) == NULL) {
1403 return (dt_link_error(dtp, elf, fd, bufs,
1404 "no such provider %s", pname));
1405 }
1406
1407 /* strlen("___") */
1408 if (strlcpy(probename, p + 3, sizeof (probename)) >=
1409 sizeof (probename))
1410 return (dt_link_error(dtp, elf, fd, bufs,
1411 "probe name too long %s", probename));
1412
1413 (void) strhyphenate(probename);
1414
1415 if ((prp = dt_probe_lookup(pvp, probename)) == NULL) {
1416 return (dt_link_error(dtp, elf, fd, bufs,
1417 "no such probe %s", probename));
1418 }
1419
1420 assert(fsym.st_value <= rela.r_offset);
1421
1422 off = rela.r_offset - fsym.st_value;
1423 if (dt_modtext(dtp, data_tgt->d_buf, eprobe,
1424 &rela, &off) != 0) {
1425 goto err;
1426 }
1427
1428 if (dt_probe_define(pvp, prp, s, r, off, eprobe) != 0) {
1429 return (dt_link_error(dtp, elf, fd, bufs,
1430 "failed to allocate space for probe"));
1431 }
1432
1433 mod = 1;
1434 (void) elf_flagdata(data_tgt, ELF_C_SET, ELF_F_DIRTY);
1435
1436 /*
1437 * This symbol may already have been marked to
1438 * be ignored by another relocation referencing
1439 * the same symbol or if this object file has
1440 * already been processed by an earlier link
1441 * invocation.
1442 */
1443 if (rsym.st_shndx != SHN_SUNW_IGNORE) {
1444 rsym.st_shndx = SHN_SUNW_IGNORE;
1445 (void) gelf_update_sym(data_sym, ndx, &rsym);
1446 }
1447 }
1448 }
1449
1450 if (mod && elf_update(elf, ELF_C_WRITE) == -1)
1451 goto err;
1452
1453 (void) elf_end(elf);
1454 (void) close(fd);
1455
1456 while ((pair = bufs) != NULL) {
1457 bufs = pair->dlp_next;
1458 dt_free(dtp, pair->dlp_str);
1459 dt_free(dtp, pair->dlp_sym);
1460 dt_free(dtp, pair);
1461 }
1462
1463 return (0);
1464
1465 err:
1466 return (dt_link_error(dtp, elf, fd, bufs,
1467 "an error was encountered while processing %s", obj));
1468 }
1469
1470 int
dtrace_program_link(dtrace_hdl_t * dtp,dtrace_prog_t * pgp,uint_t dflags,const char * file,int objc,char * const objv[])1471 dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
1472 const char *file, int objc, char *const objv[])
1473 {
1474 char drti[PATH_MAX];
1475 dof_hdr_t *dof;
1476 int fd, status, i, cur;
1477 char *cmd, tmp;
1478 size_t len;
1479 int eprobes = 0, ret = 0;
1480
1481 /*
1482 * A NULL program indicates a special use in which we just link
1483 * together a bunch of object files specified in objv and then
1484 * unlink(2) those object files.
1485 */
1486 if (pgp == NULL) {
1487 const char *fmt = "%s -o %s -r";
1488
1489 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file) + 1;
1490
1491 for (i = 0; i < objc; i++)
1492 len += strlen(objv[i]) + 1;
1493
1494 cmd = alloca(len);
1495
1496 cur = snprintf(cmd, len, fmt, dtp->dt_ld_path, file);
1497
1498 for (i = 0; i < objc; i++)
1499 cur += snprintf(cmd + cur, len - cur, " %s", objv[i]);
1500
1501 if ((status = system(cmd)) == -1) {
1502 return (dt_link_error(dtp, NULL, -1, NULL,
1503 "failed to run %s: %s", dtp->dt_ld_path,
1504 strerror(errno)));
1505 }
1506
1507 if (WIFSIGNALED(status)) {
1508 return (dt_link_error(dtp, NULL, -1, NULL,
1509 "failed to link %s: %s failed due to signal %d",
1510 file, dtp->dt_ld_path, WTERMSIG(status)));
1511 }
1512
1513 if (WEXITSTATUS(status) != 0) {
1514 return (dt_link_error(dtp, NULL, -1, NULL,
1515 "failed to link %s: %s exited with status %d\n",
1516 file, dtp->dt_ld_path, WEXITSTATUS(status)));
1517 }
1518
1519 for (i = 0; i < objc; i++) {
1520 if (strcmp(objv[i], file) != 0)
1521 (void) unlink(objv[i]);
1522 }
1523
1524 return (0);
1525 }
1526
1527 for (i = 0; i < objc; i++) {
1528 if (process_obj(dtp, objv[i], &eprobes) != 0)
1529 return (-1); /* errno is set for us */
1530 }
1531
1532 /*
1533 * If there are is-enabled probes then we need to force use of DOF
1534 * version 2.
1535 */
1536 if (eprobes && pgp->dp_dofversion < DOF_VERSION_2)
1537 pgp->dp_dofversion = DOF_VERSION_2;
1538
1539 if ((dof = dtrace_dof_create(dtp, pgp, dflags)) == NULL)
1540 return (-1); /* errno is set for us */
1541
1542 /*
1543 * Create a temporary file and then unlink it if we're going to
1544 * combine it with drti.o later. We can still refer to it in child
1545 * processes as /dev/fd/<fd>.
1546 */
1547 if ((fd = open64(file, O_RDWR | O_CREAT | O_TRUNC, 0666)) == -1) {
1548 return (dt_link_error(dtp, NULL, -1, NULL,
1549 "failed to open %s: %s", file, strerror(errno)));
1550 }
1551
1552 /*
1553 * If -xlinktype=DOF has been selected, just write out the DOF.
1554 * Otherwise proceed to the default of generating and linking ELF.
1555 */
1556 switch (dtp->dt_linktype) {
1557 case DT_LTYP_DOF:
1558 if (dt_write(dtp, fd, dof, dof->dofh_filesz) < dof->dofh_filesz)
1559 ret = errno;
1560
1561 if (close(fd) != 0 && ret == 0)
1562 ret = errno;
1563
1564 if (ret != 0) {
1565 return (dt_link_error(dtp, NULL, -1, NULL,
1566 "failed to write %s: %s", file, strerror(ret)));
1567 }
1568
1569 return (0);
1570
1571 case DT_LTYP_ELF:
1572 break; /* fall through to the rest of dtrace_program_link() */
1573
1574 default:
1575 return (dt_link_error(dtp, NULL, -1, NULL,
1576 "invalid link type %u\n", dtp->dt_linktype));
1577 }
1578
1579
1580 if (!dtp->dt_lazyload)
1581 (void) unlink(file);
1582
1583 if (dtp->dt_oflags & DTRACE_O_LP64)
1584 status = dump_elf64(dtp, dof, fd);
1585 else
1586 status = dump_elf32(dtp, dof, fd);
1587
1588 if (status != 0 || lseek(fd, 0, SEEK_SET) != 0) {
1589 return (dt_link_error(dtp, NULL, -1, NULL,
1590 "failed to write %s: %s", file, strerror(errno)));
1591 }
1592
1593 if (!dtp->dt_lazyload) {
1594 const char *fmt = "%s -o %s -r -Blocal -Breduce /dev/fd/%d %s";
1595
1596 if (dtp->dt_oflags & DTRACE_O_LP64) {
1597 (void) snprintf(drti, sizeof (drti),
1598 "%s/64/drti.o", _dtrace_libdir);
1599 } else {
1600 (void) snprintf(drti, sizeof (drti),
1601 "%s/drti.o", _dtrace_libdir);
1602 }
1603
1604 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file, fd,
1605 drti) + 1;
1606
1607 cmd = alloca(len);
1608
1609 (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, file, fd, drti);
1610
1611 if ((status = system(cmd)) == -1) {
1612 ret = dt_link_error(dtp, NULL, -1, NULL,
1613 "failed to run %s: %s", dtp->dt_ld_path,
1614 strerror(errno));
1615 goto done;
1616 }
1617
1618 (void) close(fd); /* release temporary file */
1619
1620 if (WIFSIGNALED(status)) {
1621 ret = dt_link_error(dtp, NULL, -1, NULL,
1622 "failed to link %s: %s failed due to signal %d",
1623 file, dtp->dt_ld_path, WTERMSIG(status));
1624 goto done;
1625 }
1626
1627 if (WEXITSTATUS(status) != 0) {
1628 ret = dt_link_error(dtp, NULL, -1, NULL,
1629 "failed to link %s: %s exited with status %d\n",
1630 file, dtp->dt_ld_path, WEXITSTATUS(status));
1631 goto done;
1632 }
1633 } else {
1634 (void) close(fd);
1635 }
1636
1637 done:
1638 dtrace_dof_destroy(dtp, dof);
1639 return (ret);
1640 }
1641