src/runtime/backtrace.c

   1 /*
   2  * simple backtrace facility
   3  */
   4
   5 /*
   6  * This software is part of the SBCL system. See the README file for
   7  * more information.
   8  *
   9  * This software is derived from the CMU CL system, which was
  10  * written at Carnegie Mellon University and released into the
  11  * public domain. The software is in the public domain and is
  12  * provided with absolutely no warranty. See the COPYING and CREDITS
  13  * files for more information.
  14  */
  15
  16 /* needed if we want dladdr() and Dl_Info from glibc's dlfcn.h */
  17 #define _GNU_SOURCE
  18
  19 #include <stdio.h>
  20 #include <signal.h>
  21 #include "sbcl.h"
  22 #include "runtime.h"
  23 #include "globals.h"
  24 #include "os.h"
  25 #include "interrupt.h"
  26 #include "lispregs.h"
  27 #include <wchar.h>
  28 #include "arch.h"
  29 #include "genesis/compiled-debug-fun.h"
  30 #include "genesis/compiled-debug-info.h"
  31 #include "genesis/package.h"
  32 #include "genesis/static-symbols.h"
  33 #include "genesis/primitive-objects.h"
  34 #include "thread.h"
  35 #include "gc-internal.h"
  36 #include "var-io.h"
  37
  38 #ifdef LISP_FEATURE_OS_PROVIDES_DLADDR
  39 # include <dlfcn.h>
  40 #endif
  41
  42 static void
  43 sbcl_putwc(wchar_t c, FILE *file)
  44 {
  45 #ifdef LISP_FEATURE_OS_PROVIDES_PUTWC
  46     putwc(c, file);
  47 #else
  48     if (c < 256) {
  49         fputc(c, file);
  50     } else {
  51         fputc('?', file);
  52     }
  53 #endif
  54 }
  55
  56 unsigned int decode_elsewhere_pc(lispobj packed_integer)
  57 {
  58     struct varint_unpacker unpacker;
  59     int value;
  60     varint_unpacker_init(&unpacker, packed_integer);
  61     varint_unpack(&unpacker, &value);
  62     return value;
  63 }
  64
  65 struct compiled_debug_fun *
  66 debug_function_from_pc (struct code* code, void *pc)
  67 {
  68     uword_t code_header_len = sizeof(lispobj) * code_header_words(code->header);
  69     uword_t offset
  70         = (uword_t) pc - (uword_t) code - code_header_len;
  71     struct compiled_debug_fun *df;
  72     struct compiled_debug_info *di;
  73     struct vector *v;
  74     int i, len;
  75
  76     if (!instancep(code->debug_info))
  77         return NULL;
  78
  79     di = (struct compiled_debug_info *) native_pointer(code->debug_info);
  80
  81     if (!instancep(di->fun_map))
  82         return NULL;
  83
  84     v = VECTOR(di->fun_map);
  85
  86     len = fixnum_value(v->length);
  87
  88     if (!instancep(v->data[0]))
  89         return NULL;
  90
  91     df = (struct compiled_debug_fun *) native_pointer(v->data[0]);
  92
  93     if (len == 1)
  94         return df;
  95
  96     for (i = 1;; i += 2) {
  97         unsigned next_pc;
  98
  99         if (i == len)
 100             return ((struct compiled_debug_fun *) native_pointer(v->data[i - 1]));
 101
 102         if (offset >= (uword_t)decode_elsewhere_pc(df->encoded_locs)) {
 103             struct compiled_debug_fun *p
 104                 = ((struct compiled_debug_fun *) native_pointer(v->data[i + 1]));
 105             next_pc = decode_elsewhere_pc(p->encoded_locs);
 106         } else
 107             next_pc = fixnum_value(v->data[i]);
 108
 109         if (offset < next_pc)
 110             return ((struct compiled_debug_fun *) native_pointer(v->data[i - 1]));
 111     }
 112
 113     return NULL;
 114 }
 115
 116 static void
 117 print_string (struct vector *vector)
 118 {
 119   int tag = widetag_of(vector->header);
 120
 121 #define doit(TYPE)                              \
 122   do {                                          \
 123     int i;                                      \
 124     int n = fixnum_value(vector->length);       \
 125     TYPE *data = (TYPE *) vector->data;         \
 126     for (i = 0; i < n; i++) {                   \
 127       wchar_t c = (wchar_t) data[i];            \
 128       if (c == '\\' || c == '"')                \
 129         putchar('\\');                          \
 130       sbcl_putwc(c, stdout);                    \
 131     }                                           \
 132   } while (0)
 133
 134   switch (tag) {
 135   case SIMPLE_BASE_STRING_WIDETAG:
 136     doit(unsigned char);
 137     break;
 138 #ifdef SIMPLE_CHARACTER_STRING_WIDETAG
 139   case SIMPLE_CHARACTER_STRING_WIDETAG:
 140     doit(unsigned int);
 141     break;
 142 #endif
 143   default:
 144     printf("<??? type %d>", tag);
 145   }
 146 #undef doit
 147 }
 148
 149 static int string_equal (struct vector *vector, char *string)
 150 {
 151     if (widetag_of(vector->header) != SIMPLE_BASE_STRING_WIDETAG)
 152         return 0;
 153     return !strcmp((char *) vector->data, string);
 154 }
 155
 156 static void
 157 print_entry_name (lispobj name)
 158 {
 159     if (listp(name)) {
 160         putchar('(');
 161         while (name != NIL) {
 162             if (!listp(name)) {
 163                 printf("%p: unexpected lowtag while printing a cons\n",
 164                        (void*)name);
 165                 return;
 166             }
 167             print_entry_name(CONS(name)->car);
 168             name = CONS(name)->cdr;
 169             if (name != NIL)
 170                 putchar(' ');
 171         }
 172         putchar(')');
 173     } else if (lowtag_of(name) == OTHER_POINTER_LOWTAG) {
 174         lispobj *object = native_pointer(name);
 175         if (widetag_of(*object) == SYMBOL_WIDETAG) {
 176             struct symbol *symbol = (struct symbol *) object;
 177             if (symbol->package != NIL) {
 178                 struct package *pkg
 179                     = (struct package *) native_pointer(symbol->package);
 180                 struct vector *pkg_name = VECTOR(pkg->_name);
 181                 if (string_equal(pkg_name, "COMMON-LISP"))
 182                     ;
 183                 else if (string_equal(pkg_name, "COMMON-LISP-USER")) {
 184                     fputs("CL-USER::", stdout);
 185                 }
 186                 else if (string_equal(pkg_name, "KEYWORD")) {
 187                     putchar(':');
 188                 } else {
 189                     print_string(pkg_name);
 190                     fputs("::", stdout);
 191                 }
 192             }
 193             print_string(VECTOR(symbol->name));
 194         } else if (widetag_of(*object) == SIMPLE_BASE_STRING_WIDETAG
 195 #ifdef SIMPLE_CHARACTER_STRING_WIDETAG
 196                    || widetag_of(*object) == SIMPLE_CHARACTER_STRING_WIDETAG
 197 #endif
 198             ) {
 199             putchar('"');
 200             print_string((struct vector*)object);
 201             putchar('"');
 202         } else {
 203             printf("<??? type %d>", (int) widetag_of(*object));
 204         }
 205     } else {
 206         printf("<??? lowtag %d>", (int) lowtag_of(name));
 207     }
 208 }
 209
 210 static void
 211 print_entry_points (struct code *code)
 212 {
 213     int n_funs = code_n_funs(code);
 214     for_each_simple_fun(index, fun, code, 0, {
 215         if (widetag_of(fun->header) != SIMPLE_FUN_WIDETAG) {
 216             printf("%p: bogus function entry", fun);
 217             return;
 218         }
 219         print_entry_name(fun->name);
 220         if ((index + 1) < n_funs) printf (", ");
 221     });
 222 }
 223
 224
 225 #if !(defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
 226
 227 /* KLUDGE: Sigh ... I know what the call frame looks like and it had
 228  * better not change. */
 229
 230 struct call_frame {
 231 #ifndef LISP_FEATURE_ALPHA
 232         struct call_frame *old_cont;
 233 #else
 234         u32 old_cont;
 235 #endif
 236         lispobj saved_lra;
 237         lispobj code;
 238         lispobj other_state[5];
 239 };
 240
 241 struct call_info {
 242 #ifndef LISP_FEATURE_ALPHA
 243     struct call_frame *frame;
 244 #else
 245     u32 frame;
 246 #endif
 247     int interrupted;
 248 #ifndef LISP_FEATURE_ALPHA
 249     struct code *code;
 250 #else
 251     u32 code;
 252 #endif
 253     lispobj lra;
 254     int pc; /* Note: this is the trace file offset, not the actual pc. */
 255 };
 256
 257 #define HEADER_LENGTH(header) ((header)>>8)
 258
 259 static int previous_info(struct call_info *info);
 260
 261 static struct code *
 262 code_pointer(lispobj object)
 263 {
 264     lispobj *headerp, header;
 265     int type, len;
 266
 267     headerp = native_pointer(object);
 268     header = *headerp;
 269     type = widetag_of(header);
 270
 271     switch (type) {
 272         case CODE_HEADER_WIDETAG:
 273             break;
 274         case RETURN_PC_WIDETAG:
 275         case SIMPLE_FUN_WIDETAG:
 276             len = HEADER_LENGTH(header);
 277             if (len == 0)
 278                 headerp = NULL;
 279             else
 280                 headerp -= len;
 281             break;
 282         default:
 283             headerp = NULL;
 284     }
 285
 286     return (struct code *) headerp;
 287 }
 288
 289 static boolean
 290 cs_valid_pointer_p(struct call_frame *pointer)
 291 {
 292     struct thread *thread=arch_os_get_current_thread();
 293     return (((char *) thread->control_stack_start <= (char *) pointer) &&
 294             ((char *) pointer < (char *) access_control_stack_pointer(thread)));
 295 }
 296
 297 static void
 298 call_info_from_lisp_state(struct call_info *info)
 299 {
 300     info->frame = (struct call_frame *)access_control_frame_pointer(arch_os_get_current_thread());
 301     info->interrupted = 0;
 302     info->code = NULL;
 303     info->lra = 0;
 304     info->pc = 0;
 305
 306     previous_info(info);
 307 }
 308
 309 static void
 310 call_info_from_context(struct call_info *info, os_context_t *context)
 311 {
 312     uword_t pc;
 313
 314     info->interrupted = 1;
 315 #if !defined(LISP_FEATURE_ARM) && !defined(LISP_FEATURE_ARM64)
 316     if (functionp(*os_context_register_addr(context, reg_CODE))) {
 317         /* We tried to call a function, but crapped out before $CODE could
 318          * be fixed up. Probably an undefined function. */
 319         info->frame =
 320             (struct call_frame *)(uword_t)
 321                 (*os_context_register_addr(context, reg_OCFP));
 322         info->lra = (lispobj)(*os_context_register_addr(context, reg_LRA));
 323         info->code = code_pointer(info->lra);
 324         pc = (uword_t)native_pointer(info->lra);
 325     } else
 326 #endif
 327     {
 328         info->frame =
 329             (struct call_frame *)(uword_t)
 330                 (*os_context_register_addr(context, reg_CFP));
 331         info->code =
 332             code_pointer(*os_context_register_addr(context, reg_CODE));
 333         info->lra = NIL;
 334         pc = *os_context_pc_addr(context);
 335     }
 336     if (info->code != NULL)
 337         info->pc = pc - (uword_t) info->code -
 338 #ifndef LISP_FEATURE_ALPHA
 339             (HEADER_LENGTH(info->code->header) * sizeof(lispobj));
 340 #else
 341             (HEADER_LENGTH(((struct code *)info->code)->header) * sizeof(lispobj));
 342 #endif
 343     else
 344         info->pc = 0;
 345 }
 346
 347 static int
 348 previous_info(struct call_info *info)
 349 {
 350     struct call_frame *this_frame;
 351     struct thread *thread=arch_os_get_current_thread();
 352     int free_ici;
 353     lispobj lra;
 354
 355     if (!cs_valid_pointer_p(info->frame)) {
 356         printf("Bogus callee value (0x%lx).\n", (long)info->frame);
 357         return 0;
 358     }
 359
 360     this_frame = info->frame;
 361     info->lra = this_frame->saved_lra;
 362     info->frame = this_frame->old_cont;
 363     info->interrupted = 0;
 364
 365     if (info->frame == NULL || info->frame == this_frame)
 366         return 0;
 367     lra = info->lra;
 368     if (lra == NIL) {
 369         /* We were interrupted. Find the correct signal context. */
 370         free_ici = fixnum_value(read_TLS(FREE_INTERRUPT_CONTEXT_INDEX,thread));
 371         while (free_ici-- > 0) {
 372             os_context_t *context =
 373                 thread->interrupt_contexts[free_ici];
 374             if ((struct call_frame *)(uword_t)
 375                 (*os_context_register_addr(context, reg_CFP))
 376                 == info->frame) {
 377                 call_info_from_context(info, context);
 378                 break;
 379             }
 380         }
 381     } else if (fixnump(lra)) {
 382         info->code = (struct code*)native_pointer(this_frame->code);
 383         info->pc = (uword_t)(info->code + lra);
 384         info->lra = NIL;
 385     } else {
 386         info->code = code_pointer(lra);
 387
 388         if (info->code != NULL)
 389             info->pc = (uword_t)native_pointer(info->lra) -
 390                 (uword_t)info->code -
 391 #ifndef LISP_FEATURE_ALPHA
 392                 (HEADER_LENGTH(info->code->header) * sizeof(lispobj));
 393 #else
 394         (HEADER_LENGTH(((struct code *)info->code)->header) * sizeof(lispobj));
 395 #endif
 396         else
 397             info->pc = 0;
 398     }
 399
 400     return 1;
 401 }
 402
 403 void
 404 lisp_backtrace(int nframes)
 405 {
 406     struct call_info info;
 407     int i = 0;
 408     call_info_from_lisp_state(&info);
 409
 410     do {
 411         printf("%4d: ", i);
 412
 413         if (info.code != (struct code *) 0) {
 414             struct compiled_debug_fun *df ;
 415             if (info.lra != NIL &&
 416                 (df = debug_function_from_pc((struct code *)info.code, (void *)info.lra)))
 417                 print_entry_name(df->name);
 418             else
 419                 print_entry_points((struct code *)info.code);
 420
 421             printf(" %p", (void*)((uword_t) info.code | OTHER_POINTER_LOWTAG));
 422         }
 423         else
 424             printf("CODE = ???");
 425         printf("%s fp = %p", info.interrupted ? " [interrupted]" : "",
 426                info.frame);
 427
 428         if (info.lra != NIL)
 429             printf(" LRA = %p", (void*)info.lra);
 430         else
 431             printf(" <no LRA>");
 432
 433         if (info.pc)
 434             printf(" pc = %p", (void*)(long)info.pc);
 435         putchar('\n');
 436
 437     } while (i++ < nframes && previous_info(&info));
 438 }
 439
 440 #else
 441
 442 static int
 443 altstack_pointer_p (void *p) {
 444 #ifndef LISP_FEATURE_WIN32
 445     void* stack_start = ((char*)arch_os_get_current_thread()) + dynamic_values_bytes;
 446     void* stack_end = (char*)stack_start + 32*SIGSTKSZ;
 447
 448     return (p > stack_start && p <= stack_end);
 449 #else
 450     /* Win32 doesn't do altstack */
 451     return 0;
 452 #endif
 453 }
 454
 455 static int
 456 stack_pointer_p (void *p)
 457 {
 458     /* we are using sizeof(long) here, because that is the right value on both
 459      * x86 and x86-64.  (But note that false positives would not cause much harm
 460      * given the heuristical nature of x86_call_context.) */
 461     uword_t stack_alignment = sizeof(void*);
 462     void *stack_start;
 463     struct thread *thread = arch_os_get_current_thread();
 464
 465     if (altstack_pointer_p(p))
 466         return 1;
 467
 468     if (altstack_pointer_p(&p)) {
 469         stack_start = (void *) thread->control_stack_start;
 470     } else {
 471         /* Use the current frame address, since there should be no
 472          * relevant frames below. */
 473         stack_start = &p;
 474     }
 475     return p >= stack_start
 476         && p < (void *) thread->control_stack_end
 477         && (((uword_t) p) & (stack_alignment-1)) == 0;
 478 }
 479
 480 static int
 481 ra_pointer_p (void *ra)
 482 {
 483   /* the check against 4096 is still a mystery to everyone interviewed about
 484    * it, but recent changes to sb-sprof seem to suggest that such values
 485    * do occur sometimes. */
 486   return ((uword_t) ra) > 4096 && !stack_pointer_p (ra);
 487 }
 488
 489 static int
 490 x86_call_context (void *fp, void **ra, void **ocfp)
 491 {
 492   void *c_ocfp;
 493   void *c_ra;
 494   int c_valid_p;
 495
 496   if (!stack_pointer_p(fp))
 497     return 0;
 498
 499   c_ocfp    = *((void **) fp);
 500   c_ra      = *((void **) fp + 1);
 501
 502   c_valid_p = (c_ocfp > fp
 503                && stack_pointer_p(c_ocfp)
 504                && ra_pointer_p(c_ra));
 505
 506   if (c_valid_p)
 507     *ra = c_ra, *ocfp = c_ocfp;
 508   else
 509     return 0;
 510
 511   return 1;
 512 }
 513
 514 void
 515 describe_thread_state(void)
 516 {
 517     sigset_t mask;
 518     struct thread *thread = arch_os_get_current_thread();
 519     struct interrupt_data *data = thread->interrupt_data;
 520 #ifndef LISP_FEATURE_WIN32
 521     get_current_sigmask(&mask);
 522     printf("Signal mask:\n");
 523     printf(" SIGALRM = %d\n", sigismember(&mask, SIGALRM));
 524     printf(" SIGINT = %d\n", sigismember(&mask, SIGINT));
 525     printf(" SIGPROF = %d\n", sigismember(&mask, SIGPROF));
 526 #ifdef SIG_STOP_FOR_GC
 527     printf(" SIG_STOP_FOR_GC = %d\n", sigismember(&mask, SIG_STOP_FOR_GC));
 528 #endif
 529 #endif
 530     printf("Specials:\n");
 531     printf(" *GC-INHIBIT* = %s\n", (read_TLS(GC_INHIBIT, thread) == T) ? "T" : "NIL");
 532     printf(" *GC-PENDING* = %s\n", (read_TLS(GC_PENDING, thread) == T) ? "T" : "NIL");
 533     printf(" *INTERRUPTS-ENABLED* = %s\n", (read_TLS(INTERRUPTS_ENABLED, thread) == T) ? "T" : "NIL");
 534 #ifdef STOP_FOR_GC_PENDING
 535     printf(" *STOP-FOR-GC-PENDING* = %s\n", (read_TLS(STOP_FOR_GC_PENDING, thread) == T) ? "T" : "NIL");
 536 #endif
 537     printf("Pending handler = %p\n", data->pending_handler);
 538 }
 539
 540 void print_backtrace_frame(void *pc, void *fp, int i) {
 541     lispobj *p;
 542     printf("%4d: ", i);
 543
 544     p = (lispobj *) component_ptr_from_pc((lispobj *) pc);
 545
 546     if (p) {
 547         struct code *cp = (struct code *) p;
 548         struct compiled_debug_fun *df = debug_function_from_pc(cp, pc);
 549         if (df)
 550             print_entry_name(df->name);
 551         else
 552             print_entry_points(cp);
 553         printf(", pc = %p, fp = %p", pc, fp);
 554     } else {
 555 #ifdef LISP_FEATURE_OS_PROVIDES_DLADDR
 556         Dl_info info;
 557         if (dladdr(pc, &info)) {
 558             printf("Foreign function %s, pc = %p, fp = %p", info.dli_sname, pc, fp);
 559         } else
 560 #endif
 561             printf("Foreign function, pc = %p, fp = %p", pc, fp);
 562     }
 563
 564     putchar('\n');
 565 }
 566
 567 /* This function has been split from lisp_backtrace() to enable Lisp
 568  * backtraces from gdb with call backtrace_from_fp(...). Useful for
 569  * example when debugging threading deadlocks.
 570  */
 571 void
 572 backtrace_from_fp(void *fp, int nframes, int start)
 573 {
 574   int i = start;
 575
 576   for (; i < nframes; ++i) {
 577     void *ra;
 578     void *next_fp;
 579
 580     if (!x86_call_context(fp, &ra, &next_fp))
 581       break;
 582     print_backtrace_frame(ra, next_fp, i);
 583     fp = next_fp;
 584   }
 585 }
 586
 587 void backtrace_from_context(os_context_t *context, int nframes) {
 588 #ifdef LISP_FEATURE_X86
 589     void *fp = (void *)*os_context_register_addr(context,reg_EBP);
 590 #elif defined (LISP_FEATURE_X86_64)
 591     void *fp = (void *)*os_context_register_addr(context,reg_RBP);
 592 #endif
 593     print_backtrace_frame((void *)*os_context_pc_addr(context), fp, 0);
 594     backtrace_from_fp(fp, nframes - 1, 1);
 595 }
 596
 597 void
 598 lisp_backtrace(int nframes)
 599 {
 600     struct thread *thread=arch_os_get_current_thread();
 601     int free_ici = fixnum_value(read_TLS(FREE_INTERRUPT_CONTEXT_INDEX,thread));
 602
 603     if (free_ici) {
 604         os_context_t *context = thread->interrupt_contexts[free_ici - 1];
 605         backtrace_from_context(context, nframes);
 606     } else {
 607         void *fp;
 608
 609 #ifdef LISP_FEATURE_X86
 610         asm("movl %%ebp,%0" : "=g" (fp));
 611 #elif defined (LISP_FEATURE_X86_64)
 612         asm("movq %%rbp,%0" : "=g" (fp));
 613 #endif
 614         backtrace_from_fp(fp, nframes, 0);
 615     }
 616 }
 617 #endif