breakpoints.c

   1 /*
   2  * This file is part of ltrace.
   3  * Copyright (C) 2006,2007,2011,2012,2013 Petr Machata, Red Hat Inc.
   4  * Copyright (C) 2009 Juan Cespedes
   5  * Copyright (C) 1998,2001,2002,2003,2007,2008,2009 Juan Cespedes
   6  * Copyright (C) 2006 Ian Wienand
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of the
  11  * License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  21  * 02110-1301 USA
  22  */
  23
  24 #include "config.h"
  25
  26 #include <assert.h>
  27 #include <errno.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31
  32 #ifdef __powerpc__
  33 #include <sys/ptrace.h>
  34 #endif
  35
  36 #include "backend.h"
  37 #include "breakpoint.h"
  38 #include "debug.h"
  39 #include "library.h"
  40 #include "ltrace-elf.h"
  41 #include "proc.h"
  42
  43 #ifndef ARCH_HAVE_TRANSLATE_ADDRESS
  44 int
  45 arch_translate_address_dyn(struct process *proc,
  46                        arch_addr_t addr, arch_addr_t *ret)
  47 {
  48         *ret = addr;
  49         return 0;
  50 }
  51
  52 struct ltelf;
  53 int
  54 arch_translate_address(struct ltelf *lte,
  55                        arch_addr_t addr, arch_addr_t *ret)
  56 {
  57         *ret = addr;
  58         return 0;
  59 }
  60 #endif
  61
  62 void
  63 breakpoint_on_hit(struct breakpoint *bp, struct process *proc)
  64 {
  65         assert(bp != NULL);
  66         if (bp->cbs != NULL && bp->cbs->on_hit != NULL)
  67                 (bp->cbs->on_hit)(bp, proc);
  68 }
  69
  70 void
  71 breakpoint_on_continue(struct breakpoint *bp, struct process *proc)
  72 {
  73         assert(bp != NULL);
  74         if (bp->cbs != NULL && bp->cbs->on_continue != NULL)
  75                 (bp->cbs->on_continue)(bp, proc);
  76         else
  77                 continue_after_breakpoint(proc, bp);
  78 }
  79
  80 void
  81 breakpoint_on_retract(struct breakpoint *bp, struct process *proc)
  82 {
  83         assert(bp != NULL);
  84         if (bp->cbs != NULL && bp->cbs->on_retract != NULL)
  85                 (bp->cbs->on_retract)(bp, proc);
  86 }
  87
  88 int
  89 breakpoint_get_return_bp(struct breakpoint **ret,
  90                          struct breakpoint *bp, struct process *proc)
  91 {
  92         assert(bp != NULL);
  93         if (bp->cbs != NULL && bp->cbs->get_return_bp != NULL)
  94                 return (bp->cbs->get_return_bp)(ret, bp, proc);
  95
  96         if ((*ret = create_default_return_bp(proc)) == NULL)
  97                 return -1;
  98
  99         return 0;
 100 }
 101
 102 /*****************************************************************************/
 103
 104 struct breakpoint *
 105 address2bpstruct(struct process *proc, arch_addr_t addr)
 106 {
 107         assert(proc != NULL);
 108         assert(proc->breakpoints != NULL);
 109         assert(proc->leader == proc);
 110         debug(DEBUG_FUNCTION, "address2bpstruct(pid=%d, addr=%p)", proc->pid, addr);
 111
 112         struct breakpoint *found;
 113         if (DICT_FIND_VAL(proc->breakpoints, &addr, &found) < 0)
 114                 return NULL;
 115         return found;
 116 }
 117
 118 #ifndef OS_HAVE_BREAKPOINT_DATA
 119 int
 120 os_breakpoint_init(struct process *proc, struct breakpoint *sbp)
 121 {
 122         return 0;
 123 }
 124
 125 void
 126 os_breakpoint_destroy(struct breakpoint *sbp)
 127 {
 128 }
 129
 130 int
 131 os_breakpoint_clone(struct breakpoint *retp, struct breakpoint *sbp)
 132 {
 133         return 0;
 134 }
 135 #endif
 136
 137 #ifndef ARCH_HAVE_BREAKPOINT_DATA
 138 int
 139 arch_breakpoint_init(struct process *proc, struct breakpoint *sbp)
 140 {
 141         return 0;
 142 }
 143
 144 void
 145 arch_breakpoint_destroy(struct breakpoint *sbp)
 146 {
 147 }
 148
 149 int
 150 arch_breakpoint_clone(struct breakpoint *retp, struct breakpoint *sbp)
 151 {
 152         return 0;
 153 }
 154 #endif
 155
 156 static void
 157 breakpoint_init_base(struct breakpoint *bp,
 158                      arch_addr_t addr, struct library_symbol *libsym)
 159 {
 160         bp->cbs = NULL;
 161         bp->addr = addr;
 162         memset(bp->orig_value, 0, sizeof(bp->orig_value));
 163         bp->enabled = 0;
 164         bp->libsym = libsym;
 165 }
 166
 167 /* On second thought, I don't think we need PROC.  All the translation
 168  * (arch_translate_address in particular) should be doable using
 169  * static lookups of various sections in the ELF file.  We shouldn't
 170  * need process for anything.  */
 171 int
 172 breakpoint_init(struct breakpoint *bp, struct process *proc,
 173                 arch_addr_t addr, struct library_symbol *libsym)
 174 {
 175         breakpoint_init_base(bp, addr, libsym);
 176         if (os_breakpoint_init(proc, bp) < 0)
 177                 return -1;
 178         if (arch_breakpoint_init(proc, bp) < 0) {
 179                 os_breakpoint_destroy(bp);
 180                 return -1;
 181         }
 182         return 0;
 183 }
 184
 185 void
 186 breakpoint_set_callbacks(struct breakpoint *bp, struct bp_callbacks *cbs)
 187 {
 188         if (bp->cbs != NULL)
 189                 assert(bp->cbs == NULL);
 190         bp->cbs = cbs;
 191 }
 192
 193 void
 194 breakpoint_destroy(struct breakpoint *bp)
 195 {
 196         if (bp == NULL)
 197                 return;
 198         arch_breakpoint_destroy(bp);
 199         os_breakpoint_destroy(bp);
 200 }
 201
 202 int
 203 breakpoint_clone(struct breakpoint *retp, struct process *new_proc,
 204                  struct breakpoint *bp)
 205 {
 206         struct library_symbol *libsym = NULL;
 207         if (bp->libsym != NULL) {
 208                 int rc = proc_find_symbol(new_proc, bp->libsym, NULL, &libsym);
 209                 assert(rc == 0);
 210         }
 211
 212         breakpoint_init_base(retp, bp->addr, libsym);
 213         memcpy(retp->orig_value, bp->orig_value, sizeof(bp->orig_value));
 214         retp->enabled = bp->enabled;
 215         if (os_breakpoint_clone(retp, bp) < 0)
 216                 return -1;
 217         if (arch_breakpoint_clone(retp, bp) < 0) {
 218                 os_breakpoint_destroy(retp);
 219                 return -1;
 220         }
 221         breakpoint_set_callbacks(retp, bp->cbs);
 222         return 0;
 223 }
 224
 225 int
 226 breakpoint_turn_on(struct breakpoint *bp, struct process *proc)
 227 {
 228         bp->enabled++;
 229         if (bp->enabled == 1) {
 230                 assert(proc->pid != 0);
 231                 enable_breakpoint(proc, bp);
 232         }
 233         return 0;
 234 }
 235
 236 int
 237 breakpoint_turn_off(struct breakpoint *bp, struct process *proc)
 238 {
 239         bp->enabled--;
 240         if (bp->enabled == 0)
 241                 disable_breakpoint(proc, bp);
 242         assert(bp->enabled >= 0);
 243         return 0;
 244 }
 245
 246 struct breakpoint *
 247 create_default_return_bp(struct process *proc)
 248 {
 249         struct breakpoint *bp = malloc(sizeof *bp);
 250         arch_addr_t return_addr = get_return_addr(proc, proc->stack_pointer);
 251         if (return_addr == 0 || bp == NULL
 252             || breakpoint_init(bp, proc, return_addr, NULL) < 0) {
 253                 free(bp);
 254                 return NULL;
 255         }
 256         return bp;
 257 }
 258
 259 struct breakpoint *
 260 insert_breakpoint_at(struct process *proc, arch_addr_t addr,
 261                      struct library_symbol *libsym)
 262 {
 263         debug(DEBUG_FUNCTION,
 264               "insert_breakpoint_at(pid=%d, addr=%p, symbol=%s)",
 265               proc->pid, addr, libsym ? libsym->name : "NULL");
 266
 267         assert(addr != 0);
 268
 269         struct breakpoint *bp = malloc(sizeof *bp);
 270         if (bp == NULL || breakpoint_init(bp, proc, addr, libsym) < 0) {
 271                 free(bp);
 272                 return NULL;
 273         }
 274
 275         /* N.B. (and XXX): BP->addr might differ from ADDR.  On ARM
 276          * this is a real possibility.  The problem here is that to
 277          * create a return breakpoint ltrace calls get_return_addr and
 278          * then insert_breakpoint_at.  So get_return_addr needs to
 279          * encode all the information necessary for breakpoint_init
 280          * into the address itself, so ADDR is potentially
 281          * mangled.  */
 282
 283         struct breakpoint *tmp = insert_breakpoint(proc, bp);
 284         if (tmp != bp) {
 285                 breakpoint_destroy(bp);
 286                 free(bp);
 287         }
 288         return tmp;
 289 }
 290
 291 struct breakpoint *
 292 insert_breakpoint(struct process *proc, struct breakpoint *bp)
 293 {
 294         /* Only the group leader should be getting the breakpoints and
 295          * thus have ->breakpoint initialized.  */
 296         struct process *leader = proc->leader;
 297         assert(leader != NULL);
 298         assert(leader->breakpoints != NULL);
 299
 300         /* XXX what we need to do instead is have a list of
 301          * breakpoints that are enabled at this address.  The
 302          * following works if every breakpoint is the same and there's
 303          * no extra data, but that doesn't hold anymore.  For now it
 304          * will suffice, about the only realistic case where we need
 305          * to have more than one breakpoint per address is return from
 306          * a recursive library call.  */
 307         struct breakpoint *ext_bp = bp;
 308         if (DICT_FIND_VAL(leader->breakpoints, &bp->addr, &ext_bp) != 0) {
 309                 if (proc_add_breakpoint(leader, bp) < 0)
 310                         return NULL;
 311                 ext_bp = bp;
 312         }
 313
 314         if (breakpoint_turn_on(ext_bp, proc) < 0) {
 315                 if (ext_bp != bp)
 316                         proc_remove_breakpoint(leader, bp);
 317                 return NULL;
 318         }
 319
 320         return ext_bp;
 321 }
 322
 323 void
 324 delete_breakpoint_at(struct process *proc, arch_addr_t addr)
 325 {
 326         debug(DEBUG_FUNCTION, "delete_breakpoint_at(pid=%d, addr=%p)",
 327               proc->pid, addr);
 328
 329         struct process *leader = proc->leader;
 330         assert(leader != NULL);
 331
 332         struct breakpoint *bp = NULL;
 333         DICT_FIND_VAL(leader->breakpoints, &addr, &bp);
 334         assert(bp != NULL);
 335
 336         if (delete_breakpoint(proc, bp) < 0) {
 337                 fprintf(stderr, "Couldn't turn off the breakpoint %s@%p\n",
 338                         breakpoint_name(bp), bp->addr);
 339         }
 340 }
 341
 342 int
 343 delete_breakpoint(struct process *proc, struct breakpoint *bp)
 344 {
 345         struct process *leader = proc->leader;
 346         assert(leader != NULL);
 347
 348         if (breakpoint_turn_off(bp, proc) < 0)
 349                 return -1;
 350
 351         if (bp->enabled == 0) {
 352                 proc_remove_breakpoint(leader, bp);
 353                 breakpoint_destroy(bp);
 354                 free(bp);
 355         }
 356
 357         return 0;
 358 }
 359
 360 const char *
 361 breakpoint_name(const struct breakpoint *bp)
 362 {
 363         assert(bp != NULL);
 364         return bp->libsym != NULL ? bp->libsym->name : NULL;
 365 }
 366
 367 struct library *
 368 breakpoint_library(const struct breakpoint *bp)
 369 {
 370         assert(bp != NULL);
 371         return bp->libsym != NULL ? bp->libsym->lib : NULL;
 372 }
 373
 374 static enum callback_status
 375 disable_bp_cb(arch_addr_t *addr, struct breakpoint **bpp, void *data)
 376 {
 377         struct process *proc = data;
 378         debug(DEBUG_FUNCTION, "disable_bp_cb(pid=%d)", proc->pid);
 379         if ((*bpp)->enabled)
 380                 disable_breakpoint(proc, *bpp);
 381         return CBS_CONT;
 382 }
 383
 384 void
 385 disable_all_breakpoints(struct process *proc)
 386 {
 387         debug(DEBUG_FUNCTION, "disable_all_breakpoints(pid=%d)", proc->pid);
 388         assert(proc->leader == proc);
 389         DICT_EACH(proc->breakpoints, arch_addr_t, struct breakpoint *,
 390                   NULL, disable_bp_cb, proc);
 391 }
 392
 393 static void
 394 entry_breakpoint_on_hit(struct breakpoint *bp, struct process *proc)
 395 {
 396         if (proc == NULL || proc->leader == NULL)
 397                 return;
 398         delete_breakpoint_at(proc, bp->addr);
 399         process_hit_start(proc);
 400 }
 401
 402 int
 403 entry_breakpoint_init(struct process *proc,
 404                       struct breakpoint *bp, arch_addr_t addr,
 405                       struct library *lib)
 406 {
 407         assert(addr != 0);
 408         int err = breakpoint_init(bp, proc, addr, NULL);
 409         if (err < 0)
 410                 return err;
 411
 412         static struct bp_callbacks entry_callbacks = {
 413                 .on_hit = entry_breakpoint_on_hit,
 414         };
 415         bp->cbs = &entry_callbacks;
 416         return 0;
 417 }
 418
 419 int
 420 breakpoints_init(struct process *proc)
 421 {
 422         debug(DEBUG_FUNCTION, "breakpoints_init(pid=%d)", proc->pid);
 423
 424         /* XXX breakpoint dictionary should be initialized
 425          * outside.  Here we just put in breakpoints.  */
 426         assert(proc->breakpoints != NULL);
 427
 428         /* Only the thread group leader should hold the breakpoints.  */
 429         assert(proc->leader == proc);
 430
 431         /* N.B. the following used to be conditional on this, and
 432          * maybe it still needs to be.  */
 433         assert(proc->filename != NULL);
 434
 435         struct library *lib = ltelf_read_main_binary(proc, proc->filename);
 436         struct breakpoint *entry_bp = NULL;
 437         int bp_state = 0;
 438         int result = -1;
 439         switch ((int)(lib != NULL)) {
 440         fail:
 441                 switch (bp_state) {
 442                 case 2:
 443                         proc_remove_library(proc, lib);
 444                         proc_remove_breakpoint(proc, entry_bp);
 445                 case 1:
 446                         breakpoint_destroy(entry_bp);
 447                 }
 448                 library_destroy(lib);
 449                 free(entry_bp);
 450         case 0:
 451                 return result;
 452         }
 453
 454         entry_bp = malloc(sizeof(*entry_bp));
 455         if (entry_bp == NULL
 456             || (entry_breakpoint_init(proc, entry_bp,
 457                                       lib->entry, lib)) < 0) {
 458                 fprintf(stderr,
 459                         "Couldn't initialize entry breakpoint for PID %d.\n"
 460                         "Some tracing events may be missed.\n", proc->pid);
 461                 free(entry_bp);
 462
 463         } else {
 464                 ++bp_state;
 465
 466                 if ((result = proc_add_breakpoint(proc, entry_bp)) < 0)
 467                         goto fail;
 468                 ++bp_state;
 469
 470                 if ((result = breakpoint_turn_on(entry_bp, proc)) < 0)
 471                         goto fail;
 472         }
 473         proc_add_library(proc, lib);
 474
 475         proc->callstack_depth = 0;
 476         return 0;
 477 }