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 }
--- EOF ---