Initial import from FreeBSD RELENG_4:
[dragonfly.git] / usr.bin / gcore / elfcore.c
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MD
1/*-
2 * Copyright (c) 1998 John D. Polstra
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: src/usr.bin/gcore/elfcore.c,v 1.5.2.3 2001/07/11 23:59:11 obrien Exp $
27 */
28
29#include <sys/param.h>
30#include <sys/lock.h>
31#include <sys/procfs.h>
32#include <machine/elf.h>
33#include <vm/vm_param.h>
34#include <vm/vm.h>
35#include <vm/pmap.h>
36#include <vm/vm_map.h>
37#include <err.h>
38#include <errno.h>
39#include <fcntl.h>
40#include <stdio.h>
41#include <stdlib.h>
42#include <string.h>
43#include <unistd.h>
44
45#include "extern.h"
46
47/*
48 * Code for generating ELF core dumps.
49 */
50
51typedef void (*segment_callback)(vm_map_entry_t, void *);
52
53/* Closure for cb_put_phdr(). */
54struct phdr_closure {
55 Elf_Phdr *phdr; /* Program header to fill in */
56 Elf_Off offset; /* Offset of segment in core file */
57};
58
59/* Closure for cb_size_segment(). */
60struct sseg_closure {
61 int count; /* Count of writable segments. */
62 size_t size; /* Total size of all writable segments. */
63};
64
65static void cb_put_phdr(vm_map_entry_t, void *);
66static void cb_size_segment(vm_map_entry_t, void *);
67static void each_writable_segment(vm_map_entry_t, segment_callback,
68 void *closure);
69static void elf_corehdr(int fd, pid_t, vm_map_entry_t, int numsegs,
70 void *hdr, size_t hdrsize);
71static void elf_puthdr(vm_map_entry_t, void *, size_t *,
72 const prstatus_t *, const prfpregset_t *, const prpsinfo_t *, int numsegs);
73static void elf_putnote(void *dst, size_t *off, const char *name, int type,
74 const void *desc, size_t descsz);
75static void freemap(vm_map_entry_t);
76static void readhdrinfo(pid_t, prstatus_t *, prfpregset_t *, prpsinfo_t *);
77static vm_map_entry_t readmap(pid_t);
78
79/*
80 * Write an ELF coredump for the given pid to the given fd.
81 */
82void
83elf_coredump(int fd, pid_t pid)
84{
85 vm_map_entry_t map;
86 struct sseg_closure seginfo;
87 void *hdr;
88 size_t hdrsize;
89 char memname[64];
90 int memfd;
91 Elf_Phdr *php;
92 int i;
93
94 /* Get the program's memory map. */
95 map = readmap(pid);
96
97 /* Size the program segments. */
98 seginfo.count = 0;
99 seginfo.size = 0;
100 each_writable_segment(map, cb_size_segment, &seginfo);
101
102 /*
103 * Calculate the size of the core file header area by making
104 * a dry run of generating it. Nothing is written, but the
105 * size is calculated.
106 */
107 hdrsize = 0;
108 elf_puthdr(map, (void *)NULL, &hdrsize,
109 (const prstatus_t *)NULL, (const prfpregset_t *)NULL,
110 (const prpsinfo_t *)NULL, seginfo.count);
111
112 /*
113 * Allocate memory for building the header, fill it up,
114 * and write it out.
115 */
116 hdr = malloc(hdrsize);
117 if ((hdr = malloc(hdrsize)) == NULL)
118 errx(1, "out of memory");
119 elf_corehdr(fd, pid, map, seginfo.count, hdr, hdrsize);
120
121 /* Write the contents of all of the writable segments. */
122 snprintf(memname, sizeof memname, "/proc/%d/mem", pid);
123 if ((memfd = open(memname, O_RDONLY)) == -1)
124 err(1, "cannot open %s", memname);
125
126 php = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr)) + 1;
127 for (i = 0; i < seginfo.count; i++) {
128 int nleft = php->p_filesz;
129
130 lseek(memfd, (off_t)php->p_vaddr, SEEK_SET);
131 while (nleft > 0) {
132 char buf[8*1024];
133 int nwant;
134 int ngot;
135
136 nwant = nleft;
137 if (nwant > sizeof buf)
138 nwant = sizeof buf;
139 ngot = read(memfd, buf, nwant);
140 if (ngot == -1)
141 err(1, "read from %s", memname);
142 if (ngot < nwant)
143 errx(1, "short read from %s:"
144 " wanted %d, got %d\n", memname,
145 nwant, ngot);
146 ngot = write(fd, buf, nwant);
147 if (ngot == -1)
148 err(1, "write of segment %d failed", i);
149 if (ngot != nwant)
150 errx(1, "short write");
151 nleft -= nwant;
152 }
153 php++;
154 }
155 close(memfd);
156 free(hdr);
157 freemap(map);
158}
159
160/*
161 * A callback for each_writable_segment() to write out the segment's
162 * program header entry.
163 */
164static void
165cb_put_phdr(vm_map_entry_t entry, void *closure)
166{
167 struct phdr_closure *phc = (struct phdr_closure *)closure;
168 Elf_Phdr *phdr = phc->phdr;
169
170 phc->offset = round_page(phc->offset);
171
172 phdr->p_type = PT_LOAD;
173 phdr->p_offset = phc->offset;
174 phdr->p_vaddr = entry->start;
175 phdr->p_paddr = 0;
176 phdr->p_filesz = phdr->p_memsz = entry->end - entry->start;
177 phdr->p_align = PAGE_SIZE;
178 phdr->p_flags = 0;
179 if (entry->protection & VM_PROT_READ)
180 phdr->p_flags |= PF_R;
181 if (entry->protection & VM_PROT_WRITE)
182 phdr->p_flags |= PF_W;
183 if (entry->protection & VM_PROT_EXECUTE)
184 phdr->p_flags |= PF_X;
185
186 phc->offset += phdr->p_filesz;
187 phc->phdr++;
188}
189
190/*
191 * A callback for each_writable_segment() to gather information about
192 * the number of segments and their total size.
193 */
194static void
195cb_size_segment(vm_map_entry_t entry, void *closure)
196{
197 struct sseg_closure *ssc = (struct sseg_closure *)closure;
198
199 ssc->count++;
200 ssc->size += entry->end - entry->start;
201}
202
203/*
204 * For each segment in the given memory map, call the given function
205 * with a pointer to the map entry and some arbitrary caller-supplied
206 * data.
207 */
208static void
209each_writable_segment(vm_map_entry_t map, segment_callback func, void *closure)
210{
211 vm_map_entry_t entry;
212
213 for (entry = map; entry != NULL; entry = entry->next)
214 (*func)(entry, closure);
215}
216
217/*
218 * Write the core file header to the file, including padding up to
219 * the page boundary.
220 */
221static void
222elf_corehdr(int fd, pid_t pid, vm_map_entry_t map, int numsegs, void *hdr,
223 size_t hdrsize)
224{
225 size_t off;
226 prstatus_t status;
227 prfpregset_t fpregset;
228 prpsinfo_t psinfo;
229
230 /* Gather the information for the header. */
231 readhdrinfo(pid, &status, &fpregset, &psinfo);
232
233 /* Fill in the header. */
234 memset(hdr, 0, hdrsize);
235 off = 0;
236 elf_puthdr(map, hdr, &off, &status, &fpregset, &psinfo, numsegs);
237
238 /* Write it to the core file. */
239 if (write(fd, hdr, hdrsize) == -1)
240 err(1, "write");
241}
242
243/*
244 * Generate the ELF coredump header into the buffer at "dst". "dst" may
245 * be NULL, in which case the header is sized but not actually generated.
246 */
247static void
248elf_puthdr(vm_map_entry_t map, void *dst, size_t *off, const prstatus_t *status,
249 const prfpregset_t *fpregset, const prpsinfo_t *psinfo, int numsegs)
250{
251 size_t ehoff;
252 size_t phoff;
253 size_t noteoff;
254 size_t notesz;
255
256 ehoff = *off;
257 *off += sizeof(Elf_Ehdr);
258
259 phoff = *off;
260 *off += (numsegs + 1) * sizeof(Elf_Phdr);
261
262 noteoff = *off;
263 elf_putnote(dst, off, "FreeBSD", NT_PRSTATUS, status,
264 sizeof *status);
265 elf_putnote(dst, off, "FreeBSD", NT_FPREGSET, fpregset,
266 sizeof *fpregset);
267 elf_putnote(dst, off, "FreeBSD", NT_PRPSINFO, psinfo,
268 sizeof *psinfo);
269 notesz = *off - noteoff;
270
271 /* Align up to a page boundary for the program segments. */
272 *off = round_page(*off);
273
274 if (dst != NULL) {
275 Elf_Ehdr *ehdr;
276 Elf_Phdr *phdr;
277 struct phdr_closure phc;
278
279 /*
280 * Fill in the ELF header.
281 */
282 ehdr = (Elf_Ehdr *)((char *)dst + ehoff);
283 ehdr->e_ident[EI_MAG0] = ELFMAG0;
284 ehdr->e_ident[EI_MAG1] = ELFMAG1;
285 ehdr->e_ident[EI_MAG2] = ELFMAG2;
286 ehdr->e_ident[EI_MAG3] = ELFMAG3;
287 ehdr->e_ident[EI_CLASS] = ELF_CLASS;
288 ehdr->e_ident[EI_DATA] = ELF_DATA;
289 ehdr->e_ident[EI_VERSION] = EV_CURRENT;
290 ehdr->e_ident[EI_OSABI] = ELFOSABI_FREEBSD;
291 ehdr->e_ident[EI_ABIVERSION] = 0;
292 ehdr->e_ident[EI_PAD] = 0;
293 ehdr->e_type = ET_CORE;
294 ehdr->e_machine = ELF_ARCH;
295 ehdr->e_version = EV_CURRENT;
296 ehdr->e_entry = 0;
297 ehdr->e_phoff = phoff;
298 ehdr->e_flags = 0;
299 ehdr->e_ehsize = sizeof(Elf_Ehdr);
300 ehdr->e_phentsize = sizeof(Elf_Phdr);
301 ehdr->e_phnum = numsegs + 1;
302 ehdr->e_shentsize = sizeof(Elf_Shdr);
303 ehdr->e_shnum = 0;
304 ehdr->e_shstrndx = SHN_UNDEF;
305
306 /*
307 * Fill in the program header entries.
308 */
309 phdr = (Elf_Phdr *)((char *)dst + phoff);
310
311 /* The note segement. */
312 phdr->p_type = PT_NOTE;
313 phdr->p_offset = noteoff;
314 phdr->p_vaddr = 0;
315 phdr->p_paddr = 0;
316 phdr->p_filesz = notesz;
317 phdr->p_memsz = 0;
318 phdr->p_flags = 0;
319 phdr->p_align = 0;
320 phdr++;
321
322 /* All the writable segments from the program. */
323 phc.phdr = phdr;
324 phc.offset = *off;
325 each_writable_segment(map, cb_put_phdr, &phc);
326 }
327}
328
329/*
330 * Emit one note section to "dst", or just size it if "dst" is NULL.
331 */
332static void
333elf_putnote(void *dst, size_t *off, const char *name, int type,
334 const void *desc, size_t descsz)
335{
336 Elf_Note note;
337
338 note.n_namesz = strlen(name) + 1;
339 note.n_descsz = descsz;
340 note.n_type = type;
341 if (dst != NULL)
342 bcopy(&note, (char *)dst + *off, sizeof note);
343 *off += sizeof note;
344 if (dst != NULL)
345 bcopy(name, (char *)dst + *off, note.n_namesz);
346 *off += roundup2(note.n_namesz, sizeof(Elf_Size));
347 if (dst != NULL)
348 bcopy(desc, (char *)dst + *off, note.n_descsz);
349 *off += roundup2(note.n_descsz, sizeof(Elf_Size));
350}
351
352/*
353 * Free the memory map.
354 */
355static void
356freemap(vm_map_entry_t map)
357{
358 while (map != NULL) {
359 vm_map_entry_t next = map->next;
360 free(map);
361 map = next;
362 }
363}
364
365/*
366 * Read the process information necessary to fill in the core file's header.
367 */
368static void
369readhdrinfo(pid_t pid, prstatus_t *status, prfpregset_t *fpregset,
370 prpsinfo_t *psinfo)
371{
372 char name[64];
373 char line[256];
374 int fd;
375 int i;
376 int n;
377
378 memset(status, 0, sizeof *status);
379 status->pr_version = PRSTATUS_VERSION;
380 status->pr_statussz = sizeof(prstatus_t);
381 status->pr_gregsetsz = sizeof(gregset_t);
382 status->pr_fpregsetsz = sizeof(fpregset_t);
383 status->pr_osreldate = __FreeBSD_version;
384 status->pr_pid = pid;
385
386 memset(fpregset, 0, sizeof *fpregset);
387
388 memset(psinfo, 0, sizeof *psinfo);
389 psinfo->pr_version = PRPSINFO_VERSION;
390 psinfo->pr_psinfosz = sizeof(prpsinfo_t);
391
392 /* Read the general registers. */
393 snprintf(name, sizeof name, "/proc/%d/regs", pid);
394 if ((fd = open(name, O_RDONLY)) == -1)
395 err(1, "cannot open %s", name);
396 if ((n = read(fd, &status->pr_reg, sizeof status->pr_reg)) == -1)
397 err(1, "read error from %s", name);
398 if (n < sizeof status->pr_reg)
399 errx(1, "short read from %s: wanted %u, got %d", name,
400 sizeof status->pr_reg, n);
401 close(fd);
402
403 /* Read the floating point registers. */
404 snprintf(name, sizeof name, "/proc/%d/fpregs", pid);
405 if ((fd = open(name, O_RDONLY)) == -1)
406 err(1, "cannot open %s", name);
407 if ((n = read(fd, fpregset, sizeof *fpregset)) == -1)
408 err(1, "read error from %s", name);
409 if (n < sizeof *fpregset)
410 errx(1, "short read from %s: wanted %u, got %d", name,
411 sizeof *fpregset, n);
412 close(fd);
413
414 /* Read and parse the process status. */
415 snprintf(name, sizeof name, "/proc/%d/status", pid);
416 if ((fd = open(name, O_RDONLY)) == -1)
417 err(1, "cannot open %s", name);
418 if ((n = read(fd, line, sizeof line - 1)) == -1)
419 err(1, "read error from %s", name);
420 if (n > MAXCOMLEN)
421 n = MAXCOMLEN;
422 for (i = 0; i < n && line[i] != ' '; i++)
423 psinfo->pr_fname[i] = line[i];
424 strncpy(psinfo->pr_psargs, psinfo->pr_fname, PRARGSZ);
425 close(fd);
426}
427
428/*
429 * Read the process's memory map using procfs, and return a list of
430 * VM map entries. Only the non-device read/writable segments are
431 * returned. The map entries in the list aren't fully filled in; only
432 * the items we need are present.
433 */
434static vm_map_entry_t
435readmap(pid_t pid)
436{
437 char mapname[64];
438 int mapfd;
439 ssize_t mapsize;
440 size_t bufsize;
441 char *mapbuf;
442 int pos;
443 vm_map_entry_t map;
444 vm_map_entry_t *linkp;
445
446 snprintf(mapname, sizeof mapname, "/proc/%d/map", pid);
447 if ((mapfd = open(mapname, O_RDONLY)) == -1)
448 err(1, "cannot open %s", mapname);
449
450 /*
451 * Procfs requires (for consistency) that the entire memory map
452 * be read with a single read() call. Start with a reasonbly sized
453 * buffer, and double it until it is big enough.
454 */
455 bufsize = 8 * 1024;
456 mapbuf = NULL;
457 for ( ; ; ) {
458 if ((mapbuf = realloc(mapbuf, bufsize + 1)) == NULL)
459 errx(1, "out of memory");
460 mapsize = read(mapfd, mapbuf, bufsize);
461 if (mapsize != -1 || errno != EFBIG)
462 break;
463 bufsize *= 2;
464 /* This lseek shouldn't be necessary, but it is. */
465 lseek(mapfd, (off_t)0, SEEK_SET);
466 }
467 if (mapsize == -1)
468 err(1, "read error from %s", mapname);
469 if (mapsize == 0)
470 errx(1, "empty map file %s", mapname);
471 mapbuf[mapsize] = 0;
472 close(mapfd);
473
474 pos = 0;
475 map = NULL;
476 linkp = &map;
477 while (pos < mapsize) {
478 vm_map_entry_t ent;
479 vm_offset_t start;
480 vm_offset_t end;
481 char prot[4];
482 char type[16];
483 int n;
484 int len;
485
486 len = 0;
487 n = sscanf(mapbuf + pos, "%x %x %*d %*d %*x %3[-rwx]"
488 " %*d %*d %*x %*s %*s %16s%*[\n]%n",
489 &start, &end, prot, type, &len);
490 if (n != 4)
491 errx(1, "ill-formed line in %s", mapname);
492 pos += len;
493
494 /* Ignore segments of the wrong kind, and unwritable ones */
495 if (strncmp(prot, "rw", 2) != 0 ||
496 (strcmp(type, "default") != 0 &&
497 strcmp(type, "vnode") != 0 &&
498 strcmp(type, "swap") != 0))
499 continue;
500
501 if ((ent = (vm_map_entry_t)calloc(1, sizeof *ent)) == NULL)
502 errx(1, "out of memory");
503 ent->start = start;
504 ent->end = end;
505 ent->protection = VM_PROT_READ | VM_PROT_WRITE;
506 if (prot[2] == 'x')
507 ent->protection |= VM_PROT_EXECUTE;
508
509 *linkp = ent;
510 linkp = &ent->next;
511 }
512 free(mapbuf);
513 return map;
514}