1 /* ARM EABI compliant unwinding routines. 2 Copyright (C) 2004, 2005 Free Software Foundation, Inc. 3 Contributed by Paul Brook 4 5 This file is free software; you can redistribute it and/or modify it 6 under the terms of the GNU General Public License as published by the 7 Free Software Foundation; either version 2, or (at your option) any 8 later version. 9 10 In addition to the permissions in the GNU General Public License, the 11 Free Software Foundation gives you unlimited permission to link the 12 compiled version of this file into combinations with other programs, 13 and to distribute those combinations without any restriction coming 14 from the use of this file. (The General Public License restrictions 15 do apply in other respects; for example, they cover modification of 16 the file, and distribution when not linked into a combine 17 executable.) 18 19 This file is distributed in the hope that it will be useful, but 20 WITHOUT ANY WARRANTY; without even the implied warranty of 21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 22 General Public License for more details. 23 24 You should have received a copy of the GNU General Public License 25 along with this program; see the file COPYING. If not, write to 26 the Free Software Foundation, 51 Franklin Street, Fifth Floor, 27 Boston, MA 02110-1301, USA. */ 28 29 /**************************************************************************** 30 * The functions here are derived from gcc/config/arm/unwind-arm.c from the 31 * 4.3.x release. The main changes here involve the use of ptrace to retrieve 32 * memory/processor states from a remote process. 33 ****************************************************************************/ 34 35 #include <cutils/logd.h> 36 #include <sys/ptrace.h> 37 #include <unwind.h> 38 #include "utility.h" 39 40 typedef struct _ZSt9type_info type_info; /* This names C++ type_info type */ 41 42 void __attribute__((weak)) __cxa_call_unexpected(_Unwind_Control_Block *ucbp); 43 bool __attribute__((weak)) __cxa_begin_cleanup(_Unwind_Control_Block *ucbp); 44 bool __attribute__((weak)) __cxa_type_match(_Unwind_Control_Block *ucbp, 45 const type_info *rttip, 46 bool is_reference, 47 void **matched_object); 48 49 /* Misc constants. */ 50 #define R_IP 12 51 #define R_SP 13 52 #define R_LR 14 53 #define R_PC 15 54 55 #define EXIDX_CANTUNWIND 1 56 #define uint32_highbit (((_uw) 1) << 31) 57 58 #define UCB_FORCED_STOP_FN(ucbp) ((ucbp)->unwinder_cache.reserved1) 59 #define UCB_PR_ADDR(ucbp) ((ucbp)->unwinder_cache.reserved2) 60 #define UCB_SAVED_CALLSITE_ADDR(ucbp) ((ucbp)->unwinder_cache.reserved3) 61 #define UCB_FORCED_STOP_ARG(ucbp) ((ucbp)->unwinder_cache.reserved4) 62 63 struct core_regs 64 { 65 _uw r[16]; 66 }; 67 68 /* We use normal integer types here to avoid the compiler generating 69 coprocessor instructions. */ 70 struct vfp_regs 71 { 72 _uw64 d[16]; 73 _uw pad; 74 }; 75 76 struct vfpv3_regs 77 { 78 /* Always populated via VSTM, so no need for the "pad" field from 79 vfp_regs (which is used to store the format word for FSTMX). */ 80 _uw64 d[16]; 81 }; 82 83 struct fpa_reg 84 { 85 _uw w[3]; 86 }; 87 88 struct fpa_regs 89 { 90 struct fpa_reg f[8]; 91 }; 92 93 struct wmmxd_regs 94 { 95 _uw64 wd[16]; 96 }; 97 98 struct wmmxc_regs 99 { 100 _uw wc[4]; 101 }; 102 103 /* Unwind descriptors. */ 104 105 typedef struct 106 { 107 _uw16 length; 108 _uw16 offset; 109 } EHT16; 110 111 typedef struct 112 { 113 _uw length; 114 _uw offset; 115 } EHT32; 116 117 /* The ABI specifies that the unwind routines may only use core registers, 118 except when actually manipulating coprocessor state. This allows 119 us to write one implementation that works on all platforms by 120 demand-saving coprocessor registers. 121 122 During unwinding we hold the coprocessor state in the actual hardware 123 registers and allocate demand-save areas for use during phase1 124 unwinding. */ 125 126 typedef struct 127 { 128 /* The first fields must be the same as a phase2_vrs. */ 129 _uw demand_save_flags; 130 struct core_regs core; 131 _uw prev_sp; /* Only valid during forced unwinding. */ 132 struct vfp_regs vfp; 133 struct vfpv3_regs vfp_regs_16_to_31; 134 struct fpa_regs fpa; 135 struct wmmxd_regs wmmxd; 136 struct wmmxc_regs wmmxc; 137 } phase1_vrs; 138 139 /* This must match the structure created by the assembly wrappers. */ 140 typedef struct 141 { 142 _uw demand_save_flags; 143 struct core_regs core; 144 } phase2_vrs; 145 146 147 /* An exception index table entry. */ 148 149 typedef struct __EIT_entry 150 { 151 _uw fnoffset; 152 _uw content; 153 } __EIT_entry; 154 155 /* Derived version to use ptrace */ 156 typedef _Unwind_Reason_Code (*personality_routine_with_ptrace) 157 (_Unwind_State, 158 _Unwind_Control_Block *, 159 _Unwind_Context *, 160 pid_t); 161 162 /* Derived version to use ptrace */ 163 /* ABI defined personality routines. */ 164 static _Unwind_Reason_Code unwind_cpp_pr0_with_ptrace (_Unwind_State, 165 _Unwind_Control_Block *, _Unwind_Context *, pid_t); 166 static _Unwind_Reason_Code unwind_cpp_pr1_with_ptrace (_Unwind_State, 167 _Unwind_Control_Block *, _Unwind_Context *, pid_t); 168 static _Unwind_Reason_Code unwind_cpp_pr2_with_ptrace (_Unwind_State, 169 _Unwind_Control_Block *, _Unwind_Context *, pid_t); 170 171 /* Execute the unwinding instructions described by UWS. */ 172 extern _Unwind_Reason_Code 173 unwind_execute_with_ptrace(_Unwind_Context * context, __gnu_unwind_state * uws, 174 pid_t pid); 175 176 /* Derived version to use ptrace. Only handles core registers. Disregards 177 * FP and others. 178 */ 179 /* ABI defined function to pop registers off the stack. */ 180 181 _Unwind_VRS_Result unwind_VRS_Pop_with_ptrace (_Unwind_Context *context, 182 _Unwind_VRS_RegClass regclass, 183 _uw discriminator, 184 _Unwind_VRS_DataRepresentation representation, 185 pid_t pid) 186 { 187 phase1_vrs *vrs = (phase1_vrs *) context; 188 189 switch (regclass) 190 { 191 case _UVRSC_CORE: 192 { 193 _uw *ptr; 194 _uw mask; 195 int i; 196 197 if (representation != _UVRSD_UINT32) 198 return _UVRSR_FAILED; 199 200 mask = discriminator & 0xffff; 201 ptr = (_uw *) vrs->core.r[R_SP]; 202 /* Pop the requested registers. */ 203 for (i = 0; i < 16; i++) 204 { 205 if (mask & (1 << i)) { 206 vrs->core.r[i] = get_remote_word(pid, ptr); 207 ptr++; 208 } 209 } 210 /* Writeback the stack pointer value if it wasn't restored. */ 211 if ((mask & (1 << R_SP)) == 0) 212 vrs->core.r[R_SP] = (_uw) ptr; 213 } 214 return _UVRSR_OK; 215 216 default: 217 return _UVRSR_FAILED; 218 } 219 } 220 221 /* Core unwinding functions. */ 222 223 /* Calculate the address encoded by a 31-bit self-relative offset at address 224 P. */ 225 static inline _uw 226 selfrel_offset31 (const _uw *p, pid_t pid) 227 { 228 _uw offset = get_remote_word(pid, (void*)p); 229 230 //offset = *p; 231 /* Sign extend to 32 bits. */ 232 if (offset & (1 << 30)) 233 offset |= 1u << 31; 234 else 235 offset &= ~(1u << 31); 236 237 return offset + (_uw) p; 238 } 239 240 241 /* Perform a binary search for RETURN_ADDRESS in TABLE. The table contains 242 NREC entries. */ 243 244 static const __EIT_entry * 245 search_EIT_table (const __EIT_entry * table, int nrec, _uw return_address, 246 pid_t pid) 247 { 248 _uw next_fn; 249 _uw this_fn; 250 int n, left, right; 251 252 if (nrec == 0) 253 return (__EIT_entry *) 0; 254 255 left = 0; 256 right = nrec - 1; 257 258 while (1) 259 { 260 n = (left + right) / 2; 261 this_fn = selfrel_offset31 (&table[n].fnoffset, pid); 262 if (n != nrec - 1) 263 next_fn = selfrel_offset31 (&table[n + 1].fnoffset, pid) - 1; 264 else 265 next_fn = (_uw)0 - 1; 266 267 if (return_address < this_fn) 268 { 269 if (n == left) 270 return (__EIT_entry *) 0; 271 right = n - 1; 272 } 273 else if (return_address <= next_fn) 274 return &table[n]; 275 else 276 left = n + 1; 277 } 278 } 279 280 /* Find the exception index table eintry for the given address. */ 281 static const __EIT_entry* 282 get_eitp(_uw return_address, pid_t pid, mapinfo *map, mapinfo **containing_map) 283 { 284 const __EIT_entry *eitp = NULL; 285 int nrec; 286 mapinfo *mi; 287 288 /* The return address is the address of the instruction following the 289 call instruction (plus one in thumb mode). If this was the last 290 instruction in the function the address will lie in the following 291 function. Subtract 2 from the address so that it points within the call 292 instruction itself. */ 293 if (return_address >= 2) 294 return_address -= 2; 295 296 for (mi = map; mi != NULL; mi = mi->next) { 297 if (return_address >= mi->start && return_address <= mi->end) break; 298 } 299 300 if (mi) { 301 if (containing_map) *containing_map = mi; 302 eitp = (__EIT_entry *) mi->exidx_start; 303 nrec = (mi->exidx_end - mi->exidx_start)/sizeof(__EIT_entry); 304 eitp = search_EIT_table (eitp, nrec, return_address, pid); 305 } 306 return eitp; 307 } 308 309 /* Find the exception index table eintry for the given address. 310 Fill in the relevant fields of the UCB. 311 Returns _URC_FAILURE if an error occurred, _URC_OK on success. */ 312 313 static _Unwind_Reason_Code 314 get_eit_entry (_Unwind_Control_Block *ucbp, _uw return_address, pid_t pid, 315 mapinfo *map, mapinfo **containing_map) 316 { 317 const __EIT_entry *eitp; 318 319 eitp = get_eitp(return_address, pid, map, containing_map); 320 321 if (!eitp) 322 { 323 UCB_PR_ADDR (ucbp) = 0; 324 return _URC_FAILURE; 325 } 326 ucbp->pr_cache.fnstart = selfrel_offset31 (&eitp->fnoffset, pid); 327 328 _uw eitp_content = get_remote_word(pid, (void *)&eitp->content); 329 330 /* Can this frame be unwound at all? */ 331 if (eitp_content == EXIDX_CANTUNWIND) 332 { 333 UCB_PR_ADDR (ucbp) = 0; 334 return _URC_END_OF_STACK; 335 } 336 337 /* Obtain the address of the "real" __EHT_Header word. */ 338 339 if (eitp_content & uint32_highbit) 340 { 341 /* It is immediate data. */ 342 ucbp->pr_cache.ehtp = (_Unwind_EHT_Header *)&eitp->content; 343 ucbp->pr_cache.additional = 1; 344 } 345 else 346 { 347 /* The low 31 bits of the content field are a self-relative 348 offset to an _Unwind_EHT_Entry structure. */ 349 ucbp->pr_cache.ehtp = 350 (_Unwind_EHT_Header *) selfrel_offset31 (&eitp->content, pid); 351 ucbp->pr_cache.additional = 0; 352 } 353 354 /* Discover the personality routine address. */ 355 if (get_remote_word(pid, ucbp->pr_cache.ehtp) & (1u << 31)) 356 { 357 /* One of the predefined standard routines. */ 358 _uw idx = (get_remote_word(pid, ucbp->pr_cache.ehtp) >> 24) & 0xf; 359 if (idx == 0) 360 UCB_PR_ADDR (ucbp) = (_uw) &unwind_cpp_pr0_with_ptrace; 361 else if (idx == 1) 362 UCB_PR_ADDR (ucbp) = (_uw) &unwind_cpp_pr1_with_ptrace; 363 else if (idx == 2) 364 UCB_PR_ADDR (ucbp) = (_uw) &unwind_cpp_pr2_with_ptrace; 365 else 366 { /* Failed */ 367 UCB_PR_ADDR (ucbp) = 0; 368 return _URC_FAILURE; 369 } 370 } 371 else 372 { 373 /* Execute region offset to PR */ 374 UCB_PR_ADDR (ucbp) = selfrel_offset31 (ucbp->pr_cache.ehtp, pid); 375 /* Since we are unwinding the stack from a different process, it is 376 * impossible to execute the personality routine in debuggerd. Punt here. 377 */ 378 return _URC_FAILURE; 379 } 380 return _URC_OK; 381 } 382 383 /* Print out the current call level, pc, and module name in the crash log */ 384 static _Unwind_Reason_Code log_function(_Unwind_Context *context, pid_t pid, 385 int tfd, 386 int stack_level, 387 mapinfo *map, 388 unsigned int sp_list[], 389 bool at_fault) 390 { 391 _uw pc; 392 _uw rel_pc; 393 phase2_vrs *vrs = (phase2_vrs*) context; 394 const mapinfo *mi; 395 bool only_in_tombstone = !at_fault; 396 397 if (stack_level < STACK_CONTENT_DEPTH) { 398 sp_list[stack_level] = vrs->core.r[R_SP]; 399 } 400 pc = vrs->core.r[R_PC]; 401 402 // Top level frame 403 if (stack_level == 0) { 404 pc &= ~1; 405 } 406 // For deeper framers, rollback pc by one instruction 407 else { 408 pc = vrs->core.r[R_PC]; 409 /* Thumb mode - need to check whether the bl(x) has long offset or not. 410 * Examples: 411 * 412 * arm blx in the middle of thumb: 413 * 187ae: 2300 movs r3, #0 414 * 187b0: f7fe ee1c blx 173ec 415 * 187b4: 2c00 cmp r4, #0 416 * 417 * arm bl in the middle of thumb: 418 * 187d8: 1c20 adds r0, r4, #0 419 * 187da: f136 fd15 bl 14f208 420 * 187de: 2800 cmp r0, #0 421 * 422 * pure thumb: 423 * 18894: 189b adds r3, r3, r2 424 * 18896: 4798 blx r3 425 * 18898: b001 add sp, #4 426 */ 427 if (pc & 1) { 428 _uw prev_word; 429 pc = (pc & ~1); 430 prev_word = get_remote_word(pid, (void *) pc-4); 431 // Long offset 432 if ((prev_word & 0xf0000000) == 0xf0000000 && 433 (prev_word & 0x0000e000) == 0x0000e000) { 434 pc -= 4; 435 } 436 else { 437 pc -= 2; 438 } 439 } 440 else { 441 pc -= 4; 442 } 443 } 444 445 /* We used to print the absolute PC in the back trace, and mask out the top 446 * 3 bits to guesstimate the offset in the .so file. This is not working for 447 * non-prelinked libraries since the starting offset may not be aligned on 448 * 1MB boundaries, and the library may be larger than 1MB. So for .so 449 * addresses we print the relative offset in back trace. 450 */ 451 rel_pc = pc; 452 mi = pc_to_mapinfo(map, pc, &rel_pc); 453 454 _LOG(tfd, only_in_tombstone, 455 " #%02d pc %08x %s\n", stack_level, rel_pc, 456 mi ? mi->name : ""); 457 458 return _URC_NO_REASON; 459 } 460 461 /* Derived from __gnu_Unwind_Backtrace to use ptrace */ 462 /* Perform stack backtrace through unwind data. Return the level of stack it 463 * unwinds. 464 */ 465 int unwind_backtrace_with_ptrace(int tfd, pid_t pid, mapinfo *map, 466 unsigned int sp_list[], int *frame0_pc_sane, 467 bool at_fault) 468 { 469 phase1_vrs saved_vrs; 470 _Unwind_Reason_Code code = _URC_OK; 471 struct pt_regs r; 472 int i; 473 int stack_level = 0; 474 475 _Unwind_Control_Block ucb; 476 _Unwind_Control_Block *ucbp = &ucb; 477 478 if(ptrace(PTRACE_GETREGS, pid, 0, &r)) return 0; 479 480 for (i = 0; i < 16; i++) { 481 saved_vrs.core.r[i] = r.uregs[i]; 482 /* 483 _LOG(tfd, "r[%d] = 0x%x\n", i, saved_vrs.core.r[i]); 484 */ 485 } 486 487 /* Set demand-save flags. */ 488 saved_vrs.demand_save_flags = ~(_uw) 0; 489 490 /* 491 * If the app crashes because of calling the weeds, we cannot pass the PC 492 * to the usual unwinding code as the EXIDX mapping will fail. 493 * Instead, we simply print out the 0 as the top frame, and resume the 494 * unwinding process with the value stored in LR. 495 */ 496 if (get_eitp(saved_vrs.core.r[R_PC], pid, map, NULL) == NULL) { 497 *frame0_pc_sane = 0; 498 log_function ((_Unwind_Context *) &saved_vrs, pid, tfd, stack_level, 499 map, sp_list, at_fault); 500 saved_vrs.core.r[R_PC] = saved_vrs.core.r[R_LR]; 501 stack_level++; 502 } 503 504 do { 505 mapinfo *this_map = NULL; 506 /* Find the entry for this routine. */ 507 if (get_eit_entry(ucbp, saved_vrs.core.r[R_PC], pid, map, &this_map) 508 != _URC_OK) { 509 /* Uncomment the code below to study why the unwinder failed */ 510 #if 0 511 /* Shed more debugging info for stack unwinder improvement */ 512 if (this_map) { 513 _LOG(tfd, 1, 514 "Relative PC=%#x from %s not contained in EXIDX\n", 515 saved_vrs.core.r[R_PC] - this_map->start, this_map->name); 516 } 517 _LOG(tfd, 1, "PC=%#x SP=%#x\n", 518 saved_vrs.core.r[R_PC], saved_vrs.core.r[R_SP]); 519 #endif 520 code = _URC_FAILURE; 521 break; 522 } 523 524 /* The dwarf unwinder assumes the context structure holds things 525 like the function and LSDA pointers. The ARM implementation 526 caches these in the exception header (UCB). To avoid 527 rewriting everything we make the virtual IP register point at 528 the UCB. */ 529 _Unwind_SetGR((_Unwind_Context *)&saved_vrs, 12, (_Unwind_Ptr) ucbp); 530 531 /* Call log function. */ 532 if (log_function ((_Unwind_Context *) &saved_vrs, pid, tfd, stack_level, 533 map, sp_list, at_fault) != _URC_NO_REASON) { 534 code = _URC_FAILURE; 535 break; 536 } 537 stack_level++; 538 539 /* Call the pr to decide what to do. */ 540 code = ((personality_routine_with_ptrace) UCB_PR_ADDR (ucbp))( 541 _US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND, ucbp, 542 (void *) &saved_vrs, pid); 543 /* 544 * In theory the unwinding process will stop when the end of stack is 545 * reached or there is no unwinding information for the code address. 546 * To add another level of guarantee that the unwinding process 547 * will terminate we will stop it when the STACK_CONTENT_DEPTH is reached. 548 */ 549 } while (code != _URC_END_OF_STACK && code != _URC_FAILURE && 550 stack_level < STACK_CONTENT_DEPTH); 551 return stack_level; 552 } 553 554 555 /* Derived version to use ptrace */ 556 /* Common implementation for ARM ABI defined personality routines. 557 ID is the index of the personality routine, other arguments are as defined 558 by __aeabi_unwind_cpp_pr{0,1,2}. */ 559 560 static _Unwind_Reason_Code 561 unwind_pr_common_with_ptrace (_Unwind_State state, 562 _Unwind_Control_Block *ucbp, 563 _Unwind_Context *context, 564 int id, 565 pid_t pid) 566 { 567 __gnu_unwind_state uws; 568 _uw *data; 569 int phase2_call_unexpected_after_unwind = 0; 570 571 state &= _US_ACTION_MASK; 572 573 data = (_uw *) ucbp->pr_cache.ehtp; 574 uws.data = get_remote_word(pid, data); 575 data++; 576 uws.next = data; 577 if (id == 0) 578 { 579 uws.data <<= 8; 580 uws.words_left = 0; 581 uws.bytes_left = 3; 582 } 583 else 584 { 585 uws.words_left = (uws.data >> 16) & 0xff; 586 uws.data <<= 16; 587 uws.bytes_left = 2; 588 data += uws.words_left; 589 } 590 591 /* Restore the saved pointer. */ 592 if (state == _US_UNWIND_FRAME_RESUME) 593 data = (_uw *) ucbp->cleanup_cache.bitpattern[0]; 594 595 if ((ucbp->pr_cache.additional & 1) == 0) 596 { 597 /* Process descriptors. */ 598 while (get_remote_word(pid, data)) { 599 /********************************************************************** 600 * The original code here seems to deal with exceptions that are not 601 * applicable in our toolchain, thus there is no way to test it for now. 602 * Instead of leaving it here and causing potential instability in 603 * debuggerd, we'd better punt here and leave the stack unwound. 604 * In the future when we discover cases where the stack should be unwound 605 * further but is not, we can revisit the code here. 606 **********************************************************************/ 607 return _URC_FAILURE; 608 } 609 /* Finished processing this descriptor. */ 610 } 611 612 if (unwind_execute_with_ptrace (context, &uws, pid) != _URC_OK) 613 return _URC_FAILURE; 614 615 if (phase2_call_unexpected_after_unwind) 616 { 617 /* Enter __cxa_unexpected as if called from the call site. */ 618 _Unwind_SetGR (context, R_LR, _Unwind_GetGR (context, R_PC)); 619 _Unwind_SetGR (context, R_PC, (_uw) &__cxa_call_unexpected); 620 return _URC_INSTALL_CONTEXT; 621 } 622 623 return _URC_CONTINUE_UNWIND; 624 } 625 626 627 /* ABI defined personality routine entry points. */ 628 629 static _Unwind_Reason_Code 630 unwind_cpp_pr0_with_ptrace (_Unwind_State state, 631 _Unwind_Control_Block *ucbp, 632 _Unwind_Context *context, 633 pid_t pid) 634 { 635 return unwind_pr_common_with_ptrace (state, ucbp, context, 0, pid); 636 } 637 638 static _Unwind_Reason_Code 639 unwind_cpp_pr1_with_ptrace (_Unwind_State state, 640 _Unwind_Control_Block *ucbp, 641 _Unwind_Context *context, 642 pid_t pid) 643 { 644 return unwind_pr_common_with_ptrace (state, ucbp, context, 1, pid); 645 } 646 647 static _Unwind_Reason_Code 648 unwind_cpp_pr2_with_ptrace (_Unwind_State state, 649 _Unwind_Control_Block *ucbp, 650 _Unwind_Context *context, 651 pid_t pid) 652 { 653 return unwind_pr_common_with_ptrace (state, ucbp, context, 2, pid); 654 } 655
