1 /*
2 * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include <jni.h>
26 #include <unistd.h>
27 #include <fcntl.h>
28 #include <string.h>
29 #include <stdlib.h>
30 #include <stddef.h>
31 #include <elf.h>
32 #include <link.h>
33 #include "libproc_impl.h"
34 #include "salibelf.h"
35 #include "../../../../hotspot/share/include/cds.h"
36
37 // This file has the libproc implementation to read core files.
38 // For live processes, refer to ps_proc.c. Portions of this is adapted
39 // /modelled after Solaris libproc.so (in particular Pcore.c)
40
41 //----------------------------------------------------------------------
42 // ps_prochandle cleanup helper functions
43
44 // close all file descriptors
45 static void close_files(struct ps_prochandle* ph) {
46 lib_info* lib = NULL;
47
48 // close core file descriptor
49 if (ph->core->core_fd >= 0)
50 close(ph->core->core_fd);
51
52 // close exec file descriptor
53 if (ph->core->exec_fd >= 0)
54 close(ph->core->exec_fd);
55
56 // close interp file descriptor
57 if (ph->core->interp_fd >= 0)
58 close(ph->core->interp_fd);
59
60 // close class share archive file
61 if (ph->core->classes_jsa_fd >= 0)
62 close(ph->core->classes_jsa_fd);
63
64 // close all library file descriptors
65 lib = ph->libs;
66 while (lib) {
67 int fd = lib->fd;
68 if (fd >= 0 && fd != ph->core->exec_fd) {
69 close(fd);
70 }
71 lib = lib->next;
72 }
73 }
74
75 // clean all map_info stuff
76 static void destroy_map_info(struct ps_prochandle* ph) {
77 map_info* map = ph->core->maps;
78 while (map) {
79 map_info* next = map->next;
80 free(map);
81 map = next;
82 }
83
84 if (ph->core->map_array) {
85 free(ph->core->map_array);
86 }
87
88 // Part of the class sharing workaround
89 map = ph->core->class_share_maps;
90 while (map) {
91 map_info* next = map->next;
92 free(map);
93 map = next;
94 }
95 }
96
97 // ps_prochandle operations
98 static void core_release(struct ps_prochandle* ph) {
99 if (ph->core) {
100 close_files(ph);
101 destroy_map_info(ph);
102 free(ph->core);
103 }
104 }
105
106 static map_info* allocate_init_map(int fd, off_t offset, uintptr_t vaddr, size_t memsz) {
107 map_info* map;
108 if ( (map = (map_info*) calloc(1, sizeof(map_info))) == NULL) {
109 print_debug("can't allocate memory for map_info\n");
110 return NULL;
111 }
112
113 // initialize map
114 map->fd = fd;
115 map->offset = offset;
116 map->vaddr = vaddr;
117 map->memsz = memsz;
118 return map;
119 }
120
121 // add map info with given fd, offset, vaddr and memsz
122 static map_info* add_map_info(struct ps_prochandle* ph, int fd, off_t offset,
123 uintptr_t vaddr, size_t memsz) {
124 map_info* map;
125 if ((map = allocate_init_map(fd, offset, vaddr, memsz)) == NULL) {
126 return NULL;
127 }
128
129 // add this to map list
130 map->next = ph->core->maps;
131 ph->core->maps = map;
132 ph->core->num_maps++;
133
134 return map;
135 }
136
137 // Part of the class sharing workaround
138 static map_info* add_class_share_map_info(struct ps_prochandle* ph, off_t offset,
139 uintptr_t vaddr, size_t memsz) {
140 map_info* map;
141 if ((map = allocate_init_map(ph->core->classes_jsa_fd,
142 offset, vaddr, memsz)) == NULL) {
143 return NULL;
144 }
145
146 map->next = ph->core->class_share_maps;
147 ph->core->class_share_maps = map;
148 return map;
149 }
150
151 // Return the map_info for the given virtual address. We keep a sorted
152 // array of pointers in ph->map_array, so we can binary search.
153 static map_info* core_lookup(struct ps_prochandle *ph, uintptr_t addr) {
154 int mid, lo = 0, hi = ph->core->num_maps - 1;
155 map_info *mp;
156
157 while (hi - lo > 1) {
158 mid = (lo + hi) / 2;
159 if (addr >= ph->core->map_array[mid]->vaddr) {
160 lo = mid;
161 } else {
162 hi = mid;
163 }
164 }
165
166 if (addr < ph->core->map_array[hi]->vaddr) {
167 mp = ph->core->map_array[lo];
168 } else {
169 mp = ph->core->map_array[hi];
170 }
171
172 if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) {
173 return (mp);
174 }
175
176
177 // Part of the class sharing workaround
178 // Unfortunately, we have no way of detecting -Xshare state.
179 // Check out the share maps atlast, if we don't find anywhere.
180 // This is done this way so to avoid reading share pages
181 // ahead of other normal maps. For eg. with -Xshare:off we don't
182 // want to prefer class sharing data to data from core.
183 mp = ph->core->class_share_maps;
184 if (mp) {
185 print_debug("can't locate map_info at 0x%lx, trying class share maps\n", addr);
186 }
187 while (mp) {
188 if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) {
189 print_debug("located map_info at 0x%lx from class share maps\n", addr);
190 return (mp);
191 }
192 mp = mp->next;
193 }
194
195 print_debug("can't locate map_info at 0x%lx\n", addr);
196 return (NULL);
197 }
198
199 //---------------------------------------------------------------
200 // Part of the class sharing workaround:
201 //
202 // With class sharing, pages are mapped from classes.jsa file.
203 // The read-only class sharing pages are mapped as MAP_SHARED,
204 // PROT_READ pages. These pages are not dumped into core dump.
205 // With this workaround, these pages are read from classes.jsa.
206
207 typedef struct CDSFileMapHeaderBase FileMapHeader;
208
209 static bool read_jboolean(struct ps_prochandle* ph, uintptr_t addr, jboolean* pvalue) {
210 jboolean i;
211 if (ps_pdread(ph, (psaddr_t) addr, &i, sizeof(i)) == PS_OK) {
212 *pvalue = i;
213 return true;
214 } else {
215 return false;
216 }
217 }
218
219 static bool read_pointer(struct ps_prochandle* ph, uintptr_t addr, uintptr_t* pvalue) {
220 uintptr_t uip;
221 if (ps_pdread(ph, (psaddr_t) addr, (char *)&uip, sizeof(uip)) == PS_OK) {
222 *pvalue = uip;
223 return true;
224 } else {
225 return false;
226 }
227 }
228
229 // used to read strings from debuggee
230 static bool read_string(struct ps_prochandle* ph, uintptr_t addr, char* buf, size_t size) {
231 size_t i = 0;
232 char c = ' ';
233
234 while (c != '\0') {
235 if (ps_pdread(ph, (psaddr_t) addr, &c, sizeof(char)) != PS_OK) {
236 return false;
237 }
238 if (i < size - 1) {
239 buf[i] = c;
240 } else {
241 // smaller buffer
242 return false;
243 }
244 i++; addr++;
245 }
246
247 buf[i] = '\0';
248 return true;
249 }
250
251 #define USE_SHARED_SPACES_SYM "UseSharedSpaces"
252 // mangled name of Arguments::SharedArchivePath
253 #define SHARED_ARCHIVE_PATH_SYM "_ZN9Arguments17SharedArchivePathE"
254 #define LIBJVM_NAME "/libjvm.so"
255
256 static bool init_classsharing_workaround(struct ps_prochandle* ph) {
257 lib_info* lib = ph->libs;
258 while (lib != NULL) {
259 // we are iterating over shared objects from the core dump. look for
260 // libjvm.so.
261 const char *jvm_name = 0;
262 if ((jvm_name = strstr(lib->name, LIBJVM_NAME)) != 0) {
263 char classes_jsa[PATH_MAX];
264 FileMapHeader header;
265 int fd = -1;
266 int m = 0;
267 size_t n = 0;
268 uintptr_t base = 0, useSharedSpacesAddr = 0;
269 uintptr_t sharedArchivePathAddrAddr = 0, sharedArchivePathAddr = 0;
270 jboolean useSharedSpaces = 0;
271 map_info* mi = 0;
272
273 memset(classes_jsa, 0, sizeof(classes_jsa));
274 jvm_name = lib->name;
275 useSharedSpacesAddr = lookup_symbol(ph, jvm_name, USE_SHARED_SPACES_SYM);
276 if (useSharedSpacesAddr == 0) {
277 print_debug("can't lookup 'UseSharedSpaces' flag\n");
278 return false;
279 }
280
281 // Hotspot vm types are not exported to build this library. So
282 // using equivalent type jboolean to read the value of
283 // UseSharedSpaces which is same as hotspot type "bool".
284 if (read_jboolean(ph, useSharedSpacesAddr, &useSharedSpaces) != true) {
285 print_debug("can't read the value of 'UseSharedSpaces' flag\n");
286 return false;
287 }
288
289 if ((int)useSharedSpaces == 0) {
290 print_debug("UseSharedSpaces is false, assuming -Xshare:off!\n");
291 return true;
292 }
293
294 sharedArchivePathAddrAddr = lookup_symbol(ph, jvm_name, SHARED_ARCHIVE_PATH_SYM);
295 if (sharedArchivePathAddrAddr == 0) {
296 print_debug("can't lookup shared archive path symbol\n");
297 return false;
298 }
299
300 if (read_pointer(ph, sharedArchivePathAddrAddr, &sharedArchivePathAddr) != true) {
301 print_debug("can't read shared archive path pointer\n");
302 return false;
303 }
304
305 if (read_string(ph, sharedArchivePathAddr, classes_jsa, sizeof(classes_jsa)) != true) {
306 print_debug("can't read shared archive path value\n");
307 return false;
308 }
309
310 print_debug("looking for %s\n", classes_jsa);
311 // open the class sharing archive file
312 fd = pathmap_open(classes_jsa);
313 if (fd < 0) {
314 print_debug("can't open %s!\n", classes_jsa);
315 ph->core->classes_jsa_fd = -1;
316 return false;
317 } else {
318 print_debug("opened %s\n", classes_jsa);
319 }
320
321 // read FileMapHeader from the file
322 memset(&header, 0, sizeof(FileMapHeader));
323 if ((n = read(fd, &header, sizeof(FileMapHeader)))
324 != sizeof(FileMapHeader)) {
325 print_debug("can't read shared archive file map header from %s\n", classes_jsa);
326 close(fd);
327 return false;
328 }
329
330 // check file magic
331 if (header._magic != CDS_ARCHIVE_MAGIC) {
332 print_debug("%s has bad shared archive file magic number 0x%x, expecing 0x%x\n",
333 classes_jsa, header._magic, CDS_ARCHIVE_MAGIC);
334 close(fd);
335 return false;
336 }
337
338 // check version
339 if (header._version != CURRENT_CDS_ARCHIVE_VERSION) {
340 print_debug("%s has wrong shared archive file version %d, expecting %d\n",
341 classes_jsa, header._version, CURRENT_CDS_ARCHIVE_VERSION);
342 close(fd);
343 return false;
344 }
345
346 ph->core->classes_jsa_fd = fd;
347 // add read-only maps from classes.jsa to the list of maps
348 for (m = 0; m < NUM_CDS_REGIONS; m++) {
349 if (header._space[m]._read_only) {
350 base = (uintptr_t) header._space[m]._addr._base;
351 // no need to worry about the fractional pages at-the-end.
352 // possible fractional pages are handled by core_read_data.
353 add_class_share_map_info(ph, (off_t) header._space[m]._file_offset,
354 base, (size_t) header._space[m]._used);
355 print_debug("added a share archive map at 0x%lx\n", base);
356 }
357 }
358 return true;
359 }
360 lib = lib->next;
361 }
362 return true;
363 }
364
365
366 //---------------------------------------------------------------------------
367 // functions to handle map_info
368
369 // Order mappings based on virtual address. We use this function as the
370 // callback for sorting the array of map_info pointers.
371 static int core_cmp_mapping(const void *lhsp, const void *rhsp)
372 {
373 const map_info *lhs = *((const map_info **)lhsp);
374 const map_info *rhs = *((const map_info **)rhsp);
375
376 if (lhs->vaddr == rhs->vaddr) {
377 return (0);
378 }
379
380 return (lhs->vaddr < rhs->vaddr ? -1 : 1);
381 }
382
383 // we sort map_info by starting virtual address so that we can do
384 // binary search to read from an address.
385 static bool sort_map_array(struct ps_prochandle* ph) {
386 size_t num_maps = ph->core->num_maps;
387 map_info* map = ph->core->maps;
388 int i = 0;
389
390 // allocate map_array
391 map_info** array;
392 if ( (array = (map_info**) malloc(sizeof(map_info*) * num_maps)) == NULL) {
393 print_debug("can't allocate memory for map array\n");
394 return false;
395 }
396
397 // add maps to array
398 while (map) {
399 array[i] = map;
400 i++;
401 map = map->next;
402 }
403
404 // sort is called twice. If this is second time, clear map array
405 if (ph->core->map_array) {
406 free(ph->core->map_array);
407 }
408
409 ph->core->map_array = array;
410 // sort the map_info array by base virtual address.
411 qsort(ph->core->map_array, ph->core->num_maps, sizeof (map_info*),
412 core_cmp_mapping);
413
414 // print map
415 if (is_debug()) {
416 int j = 0;
417 print_debug("---- sorted virtual address map ----\n");
418 for (j = 0; j < ph->core->num_maps; j++) {
419 print_debug("base = 0x%lx\tsize = %zu\n", ph->core->map_array[j]->vaddr,
420 ph->core->map_array[j]->memsz);
421 }
422 }
423
424 return true;
425 }
426
427 #ifndef MIN
428 #define MIN(x, y) (((x) < (y))? (x): (y))
429 #endif
430
431 static bool core_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
432 ssize_t resid = size;
433 int page_size=sysconf(_SC_PAGE_SIZE);
434 while (resid != 0) {
435 map_info *mp = core_lookup(ph, addr);
436 uintptr_t mapoff;
437 ssize_t len, rem;
438 off_t off;
439 int fd;
440
441 if (mp == NULL) {
442 break; /* No mapping for this address */
443 }
444
445 fd = mp->fd;
446 mapoff = addr - mp->vaddr;
447 len = MIN(resid, mp->memsz - mapoff);
448 off = mp->offset + mapoff;
449
450 if ((len = pread(fd, buf, len, off)) <= 0) {
451 break;
452 }
453
454 resid -= len;
455 addr += len;
456 buf = (char *)buf + len;
457
458 // mappings always start at page boundary. But, may end in fractional
459 // page. fill zeros for possible fractional page at the end of a mapping.
460 rem = mp->memsz % page_size;
461 if (rem > 0) {
462 rem = page_size - rem;
463 len = MIN(resid, rem);
464 resid -= len;
465 addr += len;
466 // we are not assuming 'buf' to be zero initialized.
467 memset(buf, 0, len);
468 buf += len;
469 }
470 }
471
472 if (resid) {
473 print_debug("core read failed for %d byte(s) @ 0x%lx (%d more bytes)\n",
474 size, addr, resid);
475 return false;
476 } else {
477 return true;
478 }
479 }
480
481 // null implementation for write
482 static bool core_write_data(struct ps_prochandle* ph,
483 uintptr_t addr, const char *buf , size_t size) {
484 return false;
485 }
486
487 static bool core_get_lwp_regs(struct ps_prochandle* ph, lwpid_t lwp_id,
488 struct user_regs_struct* regs) {
489 // for core we have cached the lwp regs from NOTE section
490 thread_info* thr = ph->threads;
491 while (thr) {
492 if (thr->lwp_id == lwp_id) {
493 memcpy(regs, &thr->regs, sizeof(struct user_regs_struct));
494 return true;
495 }
496 thr = thr->next;
497 }
498 return false;
499 }
500
501 static ps_prochandle_ops core_ops = {
502 .release= core_release,
503 .p_pread= core_read_data,
504 .p_pwrite= core_write_data,
505 .get_lwp_regs= core_get_lwp_regs
506 };
507
508 // read regs and create thread from NT_PRSTATUS entries from core file
509 static bool core_handle_prstatus(struct ps_prochandle* ph, const char* buf, size_t nbytes) {
510 // we have to read prstatus_t from buf
511 // assert(nbytes == sizeof(prstaus_t), "size mismatch on prstatus_t");
512 prstatus_t* prstat = (prstatus_t*) buf;
513 thread_info* newthr;
514 print_debug("got integer regset for lwp %d\n", prstat->pr_pid);
515 // we set pthread_t to -1 for core dump
516 if((newthr = add_thread_info(ph, (pthread_t) -1, prstat->pr_pid)) == NULL)
517 return false;
518
519 // copy regs
520 memcpy(&newthr->regs, prstat->pr_reg, sizeof(struct user_regs_struct));
521
522 if (is_debug()) {
523 print_debug("integer regset\n");
524 #ifdef i386
525 // print the regset
526 print_debug("\teax = 0x%x\n", newthr->regs.eax);
527 print_debug("\tebx = 0x%x\n", newthr->regs.ebx);
528 print_debug("\tecx = 0x%x\n", newthr->regs.ecx);
529 print_debug("\tedx = 0x%x\n", newthr->regs.edx);
530 print_debug("\tesp = 0x%x\n", newthr->regs.esp);
531 print_debug("\tebp = 0x%x\n", newthr->regs.ebp);
532 print_debug("\tesi = 0x%x\n", newthr->regs.esi);
533 print_debug("\tedi = 0x%x\n", newthr->regs.edi);
534 print_debug("\teip = 0x%x\n", newthr->regs.eip);
535 #endif
536
537 #if defined(amd64) || defined(x86_64)
538 // print the regset
539 print_debug("\tr15 = 0x%lx\n", newthr->regs.r15);
540 print_debug("\tr14 = 0x%lx\n", newthr->regs.r14);
541 print_debug("\tr13 = 0x%lx\n", newthr->regs.r13);
542 print_debug("\tr12 = 0x%lx\n", newthr->regs.r12);
543 print_debug("\trbp = 0x%lx\n", newthr->regs.rbp);
544 print_debug("\trbx = 0x%lx\n", newthr->regs.rbx);
545 print_debug("\tr11 = 0x%lx\n", newthr->regs.r11);
546 print_debug("\tr10 = 0x%lx\n", newthr->regs.r10);
547 print_debug("\tr9 = 0x%lx\n", newthr->regs.r9);
548 print_debug("\tr8 = 0x%lx\n", newthr->regs.r8);
549 print_debug("\trax = 0x%lx\n", newthr->regs.rax);
550 print_debug("\trcx = 0x%lx\n", newthr->regs.rcx);
551 print_debug("\trdx = 0x%lx\n", newthr->regs.rdx);
552 print_debug("\trsi = 0x%lx\n", newthr->regs.rsi);
553 print_debug("\trdi = 0x%lx\n", newthr->regs.rdi);
554 print_debug("\torig_rax = 0x%lx\n", newthr->regs.orig_rax);
555 print_debug("\trip = 0x%lx\n", newthr->regs.rip);
556 print_debug("\tcs = 0x%lx\n", newthr->regs.cs);
557 print_debug("\teflags = 0x%lx\n", newthr->regs.eflags);
558 print_debug("\trsp = 0x%lx\n", newthr->regs.rsp);
559 print_debug("\tss = 0x%lx\n", newthr->regs.ss);
560 print_debug("\tfs_base = 0x%lx\n", newthr->regs.fs_base);
561 print_debug("\tgs_base = 0x%lx\n", newthr->regs.gs_base);
562 print_debug("\tds = 0x%lx\n", newthr->regs.ds);
563 print_debug("\tes = 0x%lx\n", newthr->regs.es);
564 print_debug("\tfs = 0x%lx\n", newthr->regs.fs);
565 print_debug("\tgs = 0x%lx\n", newthr->regs.gs);
566 #endif
567 }
568
569 return true;
570 }
571
572 #define ROUNDUP(x, y) ((((x)+((y)-1))/(y))*(y))
573
574 // read NT_PRSTATUS entries from core NOTE segment
575 static bool core_handle_note(struct ps_prochandle* ph, ELF_PHDR* note_phdr) {
576 char* buf = NULL;
577 char* p = NULL;
578 size_t size = note_phdr->p_filesz;
579
580 // we are interested in just prstatus entries. we will ignore the rest.
581 // Advance the seek pointer to the start of the PT_NOTE data
582 if (lseek(ph->core->core_fd, note_phdr->p_offset, SEEK_SET) == (off_t)-1) {
583 print_debug("failed to lseek to PT_NOTE data\n");
584 return false;
585 }
586
587 // Now process the PT_NOTE structures. Each one is preceded by
588 // an Elf{32/64}_Nhdr structure describing its type and size.
589 if ( (buf = (char*) malloc(size)) == NULL) {
590 print_debug("can't allocate memory for reading core notes\n");
591 goto err;
592 }
593
594 // read notes into buffer
595 if (read(ph->core->core_fd, buf, size) != size) {
596 print_debug("failed to read notes, core file must have been truncated\n");
597 goto err;
598 }
599
600 p = buf;
601 while (p < buf + size) {
602 ELF_NHDR* notep = (ELF_NHDR*) p;
603 char* descdata = p + sizeof(ELF_NHDR) + ROUNDUP(notep->n_namesz, 4);
604 print_debug("Note header with n_type = %d and n_descsz = %u\n",
605 notep->n_type, notep->n_descsz);
606
607 if (notep->n_type == NT_PRSTATUS) {
608 if (core_handle_prstatus(ph, descdata, notep->n_descsz) != true) {
609 return false;
610 }
611 } else if (notep->n_type == NT_AUXV) {
612 // Get first segment from entry point
613 ELF_AUXV *auxv = (ELF_AUXV *)descdata;
614 while (auxv->a_type != AT_NULL) {
615 if (auxv->a_type == AT_ENTRY) {
616 // Set entry point address to address of dynamic section.
617 // We will adjust it in read_exec_segments().
618 ph->core->dynamic_addr = auxv->a_un.a_val;
619 break;
620 }
621 auxv++;
622 }
623 }
624 p = descdata + ROUNDUP(notep->n_descsz, 4);
625 }
626
627 free(buf);
628 return true;
629
630 err:
631 if (buf) free(buf);
632 return false;
633 }
634
635 // read all segments from core file
636 static bool read_core_segments(struct ps_prochandle* ph, ELF_EHDR* core_ehdr) {
637 int i = 0;
638 ELF_PHDR* phbuf = NULL;
639 ELF_PHDR* core_php = NULL;
640
641 if ((phbuf = read_program_header_table(ph->core->core_fd, core_ehdr)) == NULL)
642 return false;
643
644 /*
645 * Now iterate through the program headers in the core file.
646 * We're interested in two types of Phdrs: PT_NOTE (which
647 * contains a set of saved /proc structures), and PT_LOAD (which
648 * represents a memory mapping from the process's address space).
649 *
650 * Difference b/w Solaris PT_NOTE and Linux/BSD PT_NOTE:
651 *
652 * In Solaris there are two PT_NOTE segments the first PT_NOTE (if present)
653 * contains /proc structs in the pre-2.6 unstructured /proc format. the last
654 * PT_NOTE has data in new /proc format.
655 *
656 * In Solaris, there is only one pstatus (process status). pstatus contains
657 * integer register set among other stuff. For each LWP, we have one lwpstatus
658 * entry that has integer regset for that LWP.
659 *
660 * Linux threads are actually 'clone'd processes. To support core analysis
661 * of "multithreaded" process, Linux creates more than one pstatus (called
662 * "prstatus") entry in PT_NOTE. Each prstatus entry has integer regset for one
663 * "thread". Please refer to Linux kernel src file 'fs/binfmt_elf.c', in particular
664 * function "elf_core_dump".
665 */
666
667 for (core_php = phbuf, i = 0; i < core_ehdr->e_phnum; i++) {
668 switch (core_php->p_type) {
669 case PT_NOTE:
670 if (core_handle_note(ph, core_php) != true) {
671 goto err;
672 }
673 break;
674
675 case PT_LOAD: {
676 if (core_php->p_filesz != 0) {
677 if (add_map_info(ph, ph->core->core_fd, core_php->p_offset,
678 core_php->p_vaddr, core_php->p_filesz) == NULL) goto err;
679 }
680 break;
681 }
682 }
683
684 core_php++;
685 }
686
687 free(phbuf);
688 return true;
689 err:
690 free(phbuf);
691 return false;
692 }
693
694 // read segments of a shared object
695 static bool read_lib_segments(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* lib_ehdr, uintptr_t lib_base) {
696 int i = 0;
697 ELF_PHDR* phbuf;
698 ELF_PHDR* lib_php = NULL;
699
700 int page_size = sysconf(_SC_PAGE_SIZE);
701
702 if ((phbuf = read_program_header_table(lib_fd, lib_ehdr)) == NULL) {
703 return false;
704 }
705
706 // we want to process only PT_LOAD segments that are not writable.
707 // i.e., text segments. The read/write/exec (data) segments would
708 // have been already added from core file segments.
709 for (lib_php = phbuf, i = 0; i < lib_ehdr->e_phnum; i++) {
710 if ((lib_php->p_type == PT_LOAD) && !(lib_php->p_flags & PF_W) && (lib_php->p_filesz != 0)) {
711
712 uintptr_t target_vaddr = lib_php->p_vaddr + lib_base;
713 map_info *existing_map = core_lookup(ph, target_vaddr);
714
715 if (existing_map == NULL){
716 if (add_map_info(ph, lib_fd, lib_php->p_offset,
717 target_vaddr, lib_php->p_memsz) == NULL) {
718 goto err;
719 }
720 } else {
721 // Coredump stores value of p_memsz elf field
722 // rounded up to page boundary.
723
724 if ((existing_map->memsz != page_size) &&
725 (existing_map->fd != lib_fd) &&
726 (ROUNDUP(existing_map->memsz, page_size) != ROUNDUP(lib_php->p_memsz, page_size))) {
727
728 print_debug("address conflict @ 0x%lx (existing map size = %ld, size = %ld, flags = %d)\n",
729 target_vaddr, existing_map->memsz, lib_php->p_memsz, lib_php->p_flags);
730 goto err;
731 }
732
733 /* replace PT_LOAD segment with library segment */
734 print_debug("overwrote with new address mapping (memsz %ld -> %ld)\n",
735 existing_map->memsz, ROUNDUP(lib_php->p_memsz, page_size));
736
737 existing_map->fd = lib_fd;
738 existing_map->offset = lib_php->p_offset;
739 existing_map->memsz = ROUNDUP(lib_php->p_memsz, page_size);
740 }
741 }
742
743 lib_php++;
744 }
745
746 free(phbuf);
747 return true;
748 err:
749 free(phbuf);
750 return false;
751 }
752
753 // process segments from interpreter (ld.so or ld-linux.so)
754 static bool read_interp_segments(struct ps_prochandle* ph) {
755 ELF_EHDR interp_ehdr;
756
757 if (read_elf_header(ph->core->interp_fd, &interp_ehdr) != true) {
758 print_debug("interpreter is not a valid ELF file\n");
759 return false;
760 }
761
762 if (read_lib_segments(ph, ph->core->interp_fd, &interp_ehdr, ph->core->ld_base_addr) != true) {
763 print_debug("can't read segments of interpreter\n");
764 return false;
765 }
766
767 return true;
768 }
769
770 // process segments of a a.out
771 static bool read_exec_segments(struct ps_prochandle* ph, ELF_EHDR* exec_ehdr) {
772 int i = 0;
773 ELF_PHDR* phbuf = NULL;
774 ELF_PHDR* exec_php = NULL;
775
776 if ((phbuf = read_program_header_table(ph->core->exec_fd, exec_ehdr)) == NULL) {
777 return false;
778 }
779
780 for (exec_php = phbuf, i = 0; i < exec_ehdr->e_phnum; i++) {
781 switch (exec_php->p_type) {
782
783 // add mappings for PT_LOAD segments
784 case PT_LOAD: {
785 // add only non-writable segments of non-zero filesz
786 if (!(exec_php->p_flags & PF_W) && exec_php->p_filesz != 0) {
787 if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz) == NULL) goto err;
788 }
789 break;
790 }
791
792 // read the interpreter and it's segments
793 case PT_INTERP: {
794 char interp_name[BUF_SIZE + 1];
795
796 // BUF_SIZE is PATH_MAX + NAME_MAX + 1.
797 if (exec_php->p_filesz > BUF_SIZE) {
798 goto err;
799 }
800 pread(ph->core->exec_fd, interp_name, exec_php->p_filesz, exec_php->p_offset);
801 interp_name[exec_php->p_filesz] = '\0';
802 print_debug("ELF interpreter %s\n", interp_name);
803 // read interpreter segments as well
804 if ((ph->core->interp_fd = pathmap_open(interp_name)) < 0) {
805 print_debug("can't open runtime loader\n");
806 goto err;
807 }
808 break;
809 }
810
811 // from PT_DYNAMIC we want to read address of first link_map addr
812 case PT_DYNAMIC: {
813 if (exec_ehdr->e_type == ET_EXEC) {
814 ph->core->dynamic_addr = exec_php->p_vaddr;
815 } else { // ET_DYN
816 // dynamic_addr has entry point of executable.
817 // Thus we should substract it.
818 ph->core->dynamic_addr += exec_php->p_vaddr - exec_ehdr->e_entry;
819 }
820 print_debug("address of _DYNAMIC is 0x%lx\n", ph->core->dynamic_addr);
821 break;
822 }
823
824 } // switch
825 exec_php++;
826 } // for
827
828 free(phbuf);
829 return true;
830 err:
831 free(phbuf);
832 return false;
833 }
834
835
836 #define FIRST_LINK_MAP_OFFSET offsetof(struct r_debug, r_map)
837 #define LD_BASE_OFFSET offsetof(struct r_debug, r_ldbase)
838 #define LINK_MAP_ADDR_OFFSET offsetof(struct link_map, l_addr)
839 #define LINK_MAP_NAME_OFFSET offsetof(struct link_map, l_name)
840 #define LINK_MAP_NEXT_OFFSET offsetof(struct link_map, l_next)
841
842 // read shared library info from runtime linker's data structures.
843 // This work is done by librtlb_db in Solaris
844 static bool read_shared_lib_info(struct ps_prochandle* ph) {
845 uintptr_t addr = ph->core->dynamic_addr;
846 uintptr_t debug_base;
847 uintptr_t first_link_map_addr;
848 uintptr_t ld_base_addr;
849 uintptr_t link_map_addr;
850 uintptr_t lib_base_diff;
851 uintptr_t lib_base;
852 uintptr_t lib_name_addr;
853 char lib_name[BUF_SIZE];
854 ELF_DYN dyn;
855 ELF_EHDR elf_ehdr;
856 int lib_fd;
857
858 // _DYNAMIC has information of the form
859 // [tag] [data] [tag] [data] .....
860 // Both tag and data are pointer sized.
861 // We look for dynamic info with DT_DEBUG. This has shared object info.
862 // refer to struct r_debug in link.h
863
864 dyn.d_tag = DT_NULL;
865 while (dyn.d_tag != DT_DEBUG) {
866 if (ps_pdread(ph, (psaddr_t) addr, &dyn, sizeof(ELF_DYN)) != PS_OK) {
867 print_debug("can't read debug info from _DYNAMIC\n");
868 return false;
869 }
870 addr += sizeof(ELF_DYN);
871 }
872
873 // we have got Dyn entry with DT_DEBUG
874 debug_base = dyn.d_un.d_ptr;
875 // at debug_base we have struct r_debug. This has first link map in r_map field
876 if (ps_pdread(ph, (psaddr_t) debug_base + FIRST_LINK_MAP_OFFSET,
877 &first_link_map_addr, sizeof(uintptr_t)) != PS_OK) {
878 print_debug("can't read first link map address\n");
879 return false;
880 }
881
882 // read ld_base address from struct r_debug
883 if (ps_pdread(ph, (psaddr_t) debug_base + LD_BASE_OFFSET, &ld_base_addr,
884 sizeof(uintptr_t)) != PS_OK) {
885 print_debug("can't read ld base address\n");
886 return false;
887 }
888 ph->core->ld_base_addr = ld_base_addr;
889
890 print_debug("interpreter base address is 0x%lx\n", ld_base_addr);
891
892 // now read segments from interp (i.e ld.so or ld-linux.so or ld-elf.so)
893 if (read_interp_segments(ph) != true) {
894 return false;
895 }
896
897 // after adding interpreter (ld.so) mappings sort again
898 if (sort_map_array(ph) != true) {
899 return false;
900 }
901
902 print_debug("first link map is at 0x%lx\n", first_link_map_addr);
903
904 link_map_addr = first_link_map_addr;
905 while (link_map_addr != 0) {
906 // read library base address of the .so. Note that even though <sys/link.h> calls
907 // link_map->l_addr as "base address", this is * not * really base virtual
908 // address of the shared object. This is actually the difference b/w the virtual
909 // address mentioned in shared object and the actual virtual base where runtime
910 // linker loaded it. We use "base diff" in read_lib_segments call below.
911
912 if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_ADDR_OFFSET,
913 &lib_base_diff, sizeof(uintptr_t)) != PS_OK) {
914 print_debug("can't read shared object base address diff\n");
915 return false;
916 }
917
918 // read address of the name
919 if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NAME_OFFSET,
920 &lib_name_addr, sizeof(uintptr_t)) != PS_OK) {
921 print_debug("can't read address of shared object name\n");
922 return false;
923 }
924
925 // read name of the shared object
926 lib_name[0] = '\0';
927 if (lib_name_addr != 0 &&
928 read_string(ph, (uintptr_t) lib_name_addr, lib_name, sizeof(lib_name)) != true) {
929 print_debug("can't read shared object name\n");
930 // don't let failure to read the name stop opening the file. If something is really wrong
931 // it will fail later.
932 }
933
934 if (lib_name[0] != '\0') {
935 // ignore empty lib names
936 lib_fd = pathmap_open(lib_name);
937
938 if (lib_fd < 0) {
939 print_debug("can't open shared object %s\n", lib_name);
940 // continue with other libraries...
941 } else {
942 if (read_elf_header(lib_fd, &elf_ehdr)) {
943 lib_base = lib_base_diff + find_base_address(lib_fd, &elf_ehdr);
944 print_debug("reading library %s @ 0x%lx [ 0x%lx ]\n",
945 lib_name, lib_base, lib_base_diff);
946 // while adding library mappings we need to use "base difference".
947 if (! read_lib_segments(ph, lib_fd, &elf_ehdr, lib_base_diff)) {
948 print_debug("can't read shared object's segments\n");
949 close(lib_fd);
950 return false;
951 }
952 add_lib_info_fd(ph, lib_name, lib_fd, lib_base);
953 // Map info is added for the library (lib_name) so
954 // we need to re-sort it before calling the p_pdread.
955 if (sort_map_array(ph) != true)
956 return false;
957 } else {
958 print_debug("can't read ELF header for shared object %s\n", lib_name);
959 close(lib_fd);
960 // continue with other libraries...
961 }
962 }
963 }
964
965 // read next link_map address
966 if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NEXT_OFFSET,
967 &link_map_addr, sizeof(uintptr_t)) != PS_OK) {
968 print_debug("can't read next link in link_map\n");
969 return false;
970 }
971 }
972
973 return true;
974 }
975
976 // the one and only one exposed stuff from this file
977 JNIEXPORT struct ps_prochandle* JNICALL
978 Pgrab_core(const char* exec_file, const char* core_file) {
979 ELF_EHDR core_ehdr;
980 ELF_EHDR exec_ehdr;
981 ELF_EHDR lib_ehdr;
982
983 struct ps_prochandle* ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle));
984 if (ph == NULL) {
985 print_debug("can't allocate ps_prochandle\n");
986 return NULL;
987 }
988
989 if ((ph->core = (struct core_data*) calloc(1, sizeof(struct core_data))) == NULL) {
990 free(ph);
991 print_debug("can't allocate ps_prochandle\n");
992 return NULL;
993 }
994
995 // initialize ph
996 ph->ops = &core_ops;
997 ph->core->core_fd = -1;
998 ph->core->exec_fd = -1;
999 ph->core->interp_fd = -1;
1000
1001 // open the core file
1002 if ((ph->core->core_fd = open(core_file, O_RDONLY)) < 0) {
1003 print_debug("can't open core file\n");
1004 goto err;
1005 }
1006
1007 // read core file ELF header
1008 if (read_elf_header(ph->core->core_fd, &core_ehdr) != true || core_ehdr.e_type != ET_CORE) {
1009 print_debug("core file is not a valid ELF ET_CORE file\n");
1010 goto err;
1011 }
1012
1013 if ((ph->core->exec_fd = open(exec_file, O_RDONLY)) < 0) {
1014 print_debug("can't open executable file\n");
1015 goto err;
1016 }
1017
1018 if (read_elf_header(ph->core->exec_fd, &exec_ehdr) != true ||
1019 ((exec_ehdr.e_type != ET_EXEC) && (exec_ehdr.e_type != ET_DYN))) {
1020 print_debug("executable file is not a valid ELF file\n");
1021 goto err;
1022 }
1023
1024 // process core file segments
1025 if (read_core_segments(ph, &core_ehdr) != true) {
1026 goto err;
1027 }
1028
1029 // process exec file segments
1030 if (read_exec_segments(ph, &exec_ehdr) != true) {
1031 goto err;
1032 }
1033
1034 // exec file is also treated like a shared object for symbol search
1035 if (add_lib_info_fd(ph, exec_file, ph->core->exec_fd,
1036 (uintptr_t)0 + find_base_address(ph->core->exec_fd, &exec_ehdr)) == NULL) {
1037 goto err;
1038 }
1039
1040 // allocate and sort maps into map_array, we need to do this
1041 // here because read_shared_lib_info needs to read from debuggee
1042 // address space
1043 if (sort_map_array(ph) != true) {
1044 goto err;
1045 }
1046
1047 if (read_shared_lib_info(ph) != true) {
1048 goto err;
1049 }
1050
1051 // sort again because we have added more mappings from shared objects
1052 if (sort_map_array(ph) != true) {
1053 goto err;
1054 }
1055
1056 if (init_classsharing_workaround(ph) != true) {
1057 goto err;
1058 }
1059
1060 return ph;
1061
1062 err:
1063 Prelease(ph);
1064 return NULL;
1065 }