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 "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 static bool read_jboolean(struct ps_prochandle* ph, uintptr_t addr, jboolean* pvalue) {
 208   jboolean i;
 209   if (ps_pdread(ph, (psaddr_t) addr, &i, sizeof(i)) == PS_OK) {
 210     *pvalue = i;
 211     return true;
 212   } else {
 213     return false;
 214   }
 215 }
 216 
 217 static bool read_pointer(struct ps_prochandle* ph, uintptr_t addr, uintptr_t* pvalue) {
 218   uintptr_t uip;
 219   if (ps_pdread(ph, (psaddr_t) addr, (char *)&uip, sizeof(uip)) == PS_OK) {
 220     *pvalue = uip;
 221     return true;
 222   } else {
 223     return false;
 224   }
 225 }
 226 
 227 // used to read strings from debuggee
 228 static bool read_string(struct ps_prochandle* ph, uintptr_t addr, char* buf, size_t size) {
 229   size_t i = 0;
 230   char  c = ' ';
 231 
 232   while (c != '\0') {
 233     if (ps_pdread(ph, (psaddr_t) addr, &c, sizeof(char)) != PS_OK) {
 234       return false;
 235     }
 236     if (i < size - 1) {
 237       buf[i] = c;
 238     } else {
 239       // smaller buffer
 240       return false;
 241     }
 242     i++; addr++;
 243   }
 244 
 245   buf[i] = '\0';
 246   return true;
 247 }
 248 
 249 #define USE_SHARED_SPACES_SYM "UseSharedSpaces"
 250 // mangled name of Arguments::SharedArchivePath
 251 #define SHARED_ARCHIVE_PATH_SYM "_ZN9Arguments17SharedArchivePathE"
 252 #define LIBJVM_NAME "/libjvm.so"
 253 
 254 static bool init_classsharing_workaround(struct ps_prochandle* ph) {
 255   lib_info* lib = ph->libs;
 256   while (lib != NULL) {
 257     // we are iterating over shared objects from the core dump. look for
 258     // libjvm.so.
 259     const char *jvm_name = 0;
 260     if ((jvm_name = strstr(lib->name, LIBJVM_NAME)) != 0) {
 261       char classes_jsa[PATH_MAX];
 262       CDSFileMapHeaderBase header;
 263       int fd = -1;
 264       int m = 0;
 265       size_t n = 0;
 266       uintptr_t base = 0, useSharedSpacesAddr = 0;
 267       uintptr_t sharedArchivePathAddrAddr = 0, sharedArchivePathAddr = 0;
 268       jboolean useSharedSpaces = 0;
 269       map_info* mi = 0;
 270 
 271       memset(classes_jsa, 0, sizeof(classes_jsa));
 272       jvm_name = lib->name;
 273       useSharedSpacesAddr = lookup_symbol(ph, jvm_name, USE_SHARED_SPACES_SYM);
 274       if (useSharedSpacesAddr == 0) {
 275         print_debug("can't lookup 'UseSharedSpaces' flag\n");
 276         return false;
 277       }
 278 
 279       // Hotspot vm types are not exported to build this library. So
 280       // using equivalent type jboolean to read the value of
 281       // UseSharedSpaces which is same as hotspot type "bool".
 282       if (read_jboolean(ph, useSharedSpacesAddr, &useSharedSpaces) != true) {
 283         print_debug("can't read the value of 'UseSharedSpaces' flag\n");
 284         return false;
 285       }
 286 
 287       if ((int)useSharedSpaces == 0) {
 288         print_debug("UseSharedSpaces is false, assuming -Xshare:off!\n");
 289         return true;
 290       }
 291 
 292       sharedArchivePathAddrAddr = lookup_symbol(ph, jvm_name, SHARED_ARCHIVE_PATH_SYM);
 293       if (sharedArchivePathAddrAddr == 0) {
 294         print_debug("can't lookup shared archive path symbol\n");
 295         return false;
 296       }
 297 
 298       if (read_pointer(ph, sharedArchivePathAddrAddr, &sharedArchivePathAddr) != true) {
 299         print_debug("can't read shared archive path pointer\n");
 300         return false;
 301       }
 302 
 303       if (read_string(ph, sharedArchivePathAddr, classes_jsa, sizeof(classes_jsa)) != true) {
 304         print_debug("can't read shared archive path value\n");
 305         return false;
 306       }
 307 
 308       print_debug("looking for %s\n", classes_jsa);
 309       // open the class sharing archive file
 310       fd = pathmap_open(classes_jsa);
 311       if (fd < 0) {
 312         print_debug("can't open %s!\n", classes_jsa);
 313         ph->core->classes_jsa_fd = -1;
 314         return false;
 315       } else {
 316         print_debug("opened %s\n", classes_jsa);
 317       }
 318 
 319       // read CDSFileMapHeaderBase from the file
 320       memset(&header, 0, sizeof(CDSFileMapHeaderBase));
 321       if ((n = read(fd, &header, sizeof(CDSFileMapHeaderBase)))
 322            != sizeof(CDSFileMapHeaderBase)) {
 323         print_debug("can't read shared archive file map header from %s\n", classes_jsa);
 324         close(fd);
 325         return false;
 326       }
 327 
 328       // check file magic
 329       if (header._magic != CDS_ARCHIVE_MAGIC) {
 330         print_debug("%s has bad shared archive file magic number 0x%x, expecting 0x%x\n",
 331                     classes_jsa, header._magic, CDS_ARCHIVE_MAGIC);
 332         close(fd);
 333         return false;
 334       }
 335 
 336       // check version
 337       if (header._version != CURRENT_CDS_ARCHIVE_VERSION) {
 338         print_debug("%s has wrong shared archive file version %d, expecting %d\n",
 339                      classes_jsa, header._version, CURRENT_CDS_ARCHIVE_VERSION);
 340         close(fd);
 341         return false;
 342       }
 343 
 344       ph->core->classes_jsa_fd = fd;
 345       // add read-only maps from classes.jsa to the list of maps
 346       for (m = 0; m < NUM_CDS_REGIONS; m++) {
 347         if (header._space[m]._read_only) {
 348           base = (uintptr_t) header._space[m]._addr._base;
 349           // no need to worry about the fractional pages at-the-end.
 350           // possible fractional pages are handled by core_read_data.
 351           add_class_share_map_info(ph, (off_t) header._space[m]._file_offset,
 352                                    base, (size_t) header._space[m]._used);
 353           print_debug("added a share archive map at 0x%lx\n", base);
 354         }
 355       }
 356       return true;
 357    }
 358    lib = lib->next;
 359   }
 360   return true;
 361 }
 362 
 363 
 364 //---------------------------------------------------------------------------
 365 // functions to handle map_info
 366 
 367 // Order mappings based on virtual address.  We use this function as the
 368 // callback for sorting the array of map_info pointers.
 369 static int core_cmp_mapping(const void *lhsp, const void *rhsp)
 370 {
 371   const map_info *lhs = *((const map_info **)lhsp);
 372   const map_info *rhs = *((const map_info **)rhsp);
 373 
 374   if (lhs->vaddr == rhs->vaddr) {
 375     return (0);
 376   }
 377 
 378   return (lhs->vaddr < rhs->vaddr ? -1 : 1);
 379 }
 380 
 381 // we sort map_info by starting virtual address so that we can do
 382 // binary search to read from an address.
 383 static bool sort_map_array(struct ps_prochandle* ph) {
 384   size_t num_maps = ph->core->num_maps;
 385   map_info* map = ph->core->maps;
 386   int i = 0;
 387 
 388   // allocate map_array
 389   map_info** array;
 390   if ( (array = (map_info**) malloc(sizeof(map_info*) * num_maps)) == NULL) {
 391     print_debug("can't allocate memory for map array\n");
 392     return false;
 393   }
 394 
 395   // add maps to array
 396   while (map) {
 397     array[i] = map;
 398     i++;
 399     map = map->next;
 400   }
 401 
 402   // sort is called twice. If this is second time, clear map array
 403   if (ph->core->map_array) {
 404     free(ph->core->map_array);
 405   }
 406 
 407   ph->core->map_array = array;
 408   // sort the map_info array by base virtual address.
 409   qsort(ph->core->map_array, ph->core->num_maps, sizeof (map_info*),
 410         core_cmp_mapping);
 411 
 412   // print map
 413   if (is_debug()) {
 414     int j = 0;
 415     print_debug("---- sorted virtual address map ----\n");
 416     for (j = 0; j < ph->core->num_maps; j++) {
 417       print_debug("base = 0x%lx\tsize = %zu\n", ph->core->map_array[j]->vaddr,
 418                   ph->core->map_array[j]->memsz);
 419     }
 420   }
 421 
 422   return true;
 423 }
 424 
 425 #ifndef MIN
 426 #define MIN(x, y) (((x) < (y))? (x): (y))
 427 #endif
 428 
 429 static bool core_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
 430    ssize_t resid = size;
 431    int page_size=sysconf(_SC_PAGE_SIZE);
 432    while (resid != 0) {
 433       map_info *mp = core_lookup(ph, addr);
 434       uintptr_t mapoff;
 435       ssize_t len, rem;
 436       off_t off;
 437       int fd;
 438 
 439       if (mp == NULL) {
 440          break;  /* No mapping for this address */
 441       }
 442 
 443       fd = mp->fd;
 444       mapoff = addr - mp->vaddr;
 445       len = MIN(resid, mp->memsz - mapoff);
 446       off = mp->offset + mapoff;
 447 
 448       if ((len = pread(fd, buf, len, off)) <= 0) {
 449          break;
 450       }
 451 
 452       resid -= len;
 453       addr += len;
 454       buf = (char *)buf + len;
 455 
 456       // mappings always start at page boundary. But, may end in fractional
 457       // page. fill zeros for possible fractional page at the end of a mapping.
 458       rem = mp->memsz % page_size;
 459       if (rem > 0) {
 460          rem = page_size - rem;
 461          len = MIN(resid, rem);
 462          resid -= len;
 463          addr += len;
 464          // we are not assuming 'buf' to be zero initialized.
 465          memset(buf, 0, len);
 466          buf += len;
 467       }
 468    }
 469 
 470    if (resid) {
 471       print_debug("core read failed for %d byte(s) @ 0x%lx (%d more bytes)\n",
 472               size, addr, resid);
 473       return false;
 474    } else {
 475       return true;
 476    }
 477 }
 478 
 479 // null implementation for write
 480 static bool core_write_data(struct ps_prochandle* ph,
 481                              uintptr_t addr, const char *buf , size_t size) {
 482    return false;
 483 }
 484 
 485 static bool core_get_lwp_regs(struct ps_prochandle* ph, lwpid_t lwp_id,
 486                           struct user_regs_struct* regs) {
 487    // for core we have cached the lwp regs from NOTE section
 488    thread_info* thr = ph->threads;
 489    while (thr) {
 490      if (thr->lwp_id == lwp_id) {
 491        memcpy(regs, &thr->regs, sizeof(struct user_regs_struct));
 492        return true;
 493      }
 494      thr = thr->next;
 495    }
 496    return false;
 497 }
 498 
 499 static ps_prochandle_ops core_ops = {
 500    .release=  core_release,
 501    .p_pread=  core_read_data,
 502    .p_pwrite= core_write_data,
 503    .get_lwp_regs= core_get_lwp_regs
 504 };
 505 
 506 // read regs and create thread from NT_PRSTATUS entries from core file
 507 static bool core_handle_prstatus(struct ps_prochandle* ph, const char* buf, size_t nbytes) {
 508    // we have to read prstatus_t from buf
 509    // assert(nbytes == sizeof(prstaus_t), "size mismatch on prstatus_t");
 510    prstatus_t* prstat = (prstatus_t*) buf;
 511    thread_info* newthr;
 512    print_debug("got integer regset for lwp %d\n", prstat->pr_pid);
 513    // we set pthread_t to -1 for core dump
 514    if((newthr = add_thread_info(ph, (pthread_t) -1,  prstat->pr_pid)) == NULL)
 515       return false;
 516 
 517    // copy regs
 518    memcpy(&newthr->regs, prstat->pr_reg, sizeof(struct user_regs_struct));
 519 
 520    if (is_debug()) {
 521       print_debug("integer regset\n");
 522 #ifdef i386
 523       // print the regset
 524       print_debug("\teax = 0x%x\n", newthr->regs.eax);
 525       print_debug("\tebx = 0x%x\n", newthr->regs.ebx);
 526       print_debug("\tecx = 0x%x\n", newthr->regs.ecx);
 527       print_debug("\tedx = 0x%x\n", newthr->regs.edx);
 528       print_debug("\tesp = 0x%x\n", newthr->regs.esp);
 529       print_debug("\tebp = 0x%x\n", newthr->regs.ebp);
 530       print_debug("\tesi = 0x%x\n", newthr->regs.esi);
 531       print_debug("\tedi = 0x%x\n", newthr->regs.edi);
 532       print_debug("\teip = 0x%x\n", newthr->regs.eip);
 533 #endif
 534 
 535 #if defined(amd64) || defined(x86_64)
 536       // print the regset
 537       print_debug("\tr15 = 0x%lx\n", newthr->regs.r15);
 538       print_debug("\tr14 = 0x%lx\n", newthr->regs.r14);
 539       print_debug("\tr13 = 0x%lx\n", newthr->regs.r13);
 540       print_debug("\tr12 = 0x%lx\n", newthr->regs.r12);
 541       print_debug("\trbp = 0x%lx\n", newthr->regs.rbp);
 542       print_debug("\trbx = 0x%lx\n", newthr->regs.rbx);
 543       print_debug("\tr11 = 0x%lx\n", newthr->regs.r11);
 544       print_debug("\tr10 = 0x%lx\n", newthr->regs.r10);
 545       print_debug("\tr9 = 0x%lx\n", newthr->regs.r9);
 546       print_debug("\tr8 = 0x%lx\n", newthr->regs.r8);
 547       print_debug("\trax = 0x%lx\n", newthr->regs.rax);
 548       print_debug("\trcx = 0x%lx\n", newthr->regs.rcx);
 549       print_debug("\trdx = 0x%lx\n", newthr->regs.rdx);
 550       print_debug("\trsi = 0x%lx\n", newthr->regs.rsi);
 551       print_debug("\trdi = 0x%lx\n", newthr->regs.rdi);
 552       print_debug("\torig_rax = 0x%lx\n", newthr->regs.orig_rax);
 553       print_debug("\trip = 0x%lx\n", newthr->regs.rip);
 554       print_debug("\tcs = 0x%lx\n", newthr->regs.cs);
 555       print_debug("\teflags = 0x%lx\n", newthr->regs.eflags);
 556       print_debug("\trsp = 0x%lx\n", newthr->regs.rsp);
 557       print_debug("\tss = 0x%lx\n", newthr->regs.ss);
 558       print_debug("\tfs_base = 0x%lx\n", newthr->regs.fs_base);
 559       print_debug("\tgs_base = 0x%lx\n", newthr->regs.gs_base);
 560       print_debug("\tds = 0x%lx\n", newthr->regs.ds);
 561       print_debug("\tes = 0x%lx\n", newthr->regs.es);
 562       print_debug("\tfs = 0x%lx\n", newthr->regs.fs);
 563       print_debug("\tgs = 0x%lx\n", newthr->regs.gs);
 564 #endif
 565    }
 566 
 567    return true;
 568 }
 569 
 570 #define ROUNDUP(x, y)  ((((x)+((y)-1))/(y))*(y))
 571 
 572 // read NT_PRSTATUS entries from core NOTE segment
 573 static bool core_handle_note(struct ps_prochandle* ph, ELF_PHDR* note_phdr) {
 574    char* buf = NULL;
 575    char* p = NULL;
 576    size_t size = note_phdr->p_filesz;
 577 
 578    // we are interested in just prstatus entries. we will ignore the rest.
 579    // Advance the seek pointer to the start of the PT_NOTE data
 580    if (lseek(ph->core->core_fd, note_phdr->p_offset, SEEK_SET) == (off_t)-1) {
 581       print_debug("failed to lseek to PT_NOTE data\n");
 582       return false;
 583    }
 584 
 585    // Now process the PT_NOTE structures.  Each one is preceded by
 586    // an Elf{32/64}_Nhdr structure describing its type and size.
 587    if ( (buf = (char*) malloc(size)) == NULL) {
 588       print_debug("can't allocate memory for reading core notes\n");
 589       goto err;
 590    }
 591 
 592    // read notes into buffer
 593    if (read(ph->core->core_fd, buf, size) != size) {
 594       print_debug("failed to read notes, core file must have been truncated\n");
 595       goto err;
 596    }
 597 
 598    p = buf;
 599    while (p < buf + size) {
 600       ELF_NHDR* notep = (ELF_NHDR*) p;
 601       char* descdata  = p + sizeof(ELF_NHDR) + ROUNDUP(notep->n_namesz, 4);
 602       print_debug("Note header with n_type = %d and n_descsz = %u\n",
 603                                    notep->n_type, notep->n_descsz);
 604 
 605       if (notep->n_type == NT_PRSTATUS) {
 606         if (core_handle_prstatus(ph, descdata, notep->n_descsz) != true) {
 607           return false;
 608         }
 609       } else if (notep->n_type == NT_AUXV) {
 610         // Get first segment from entry point
 611         ELF_AUXV *auxv = (ELF_AUXV *)descdata;
 612         while (auxv->a_type != AT_NULL) {
 613           if (auxv->a_type == AT_ENTRY) {
 614             // Set entry point address to address of dynamic section.
 615             // We will adjust it in read_exec_segments().
 616             ph->core->dynamic_addr = auxv->a_un.a_val;
 617             break;
 618           }
 619           auxv++;
 620         }
 621       }
 622       p = descdata + ROUNDUP(notep->n_descsz, 4);
 623    }
 624 
 625    free(buf);
 626    return true;
 627 
 628 err:
 629    if (buf) free(buf);
 630    return false;
 631 }
 632 
 633 // read all segments from core file
 634 static bool read_core_segments(struct ps_prochandle* ph, ELF_EHDR* core_ehdr) {
 635    int i = 0;
 636    ELF_PHDR* phbuf = NULL;
 637    ELF_PHDR* core_php = NULL;
 638 
 639    if ((phbuf =  read_program_header_table(ph->core->core_fd, core_ehdr)) == NULL)
 640       return false;
 641 
 642    /*
 643     * Now iterate through the program headers in the core file.
 644     * We're interested in two types of Phdrs: PT_NOTE (which
 645     * contains a set of saved /proc structures), and PT_LOAD (which
 646     * represents a memory mapping from the process's address space).
 647     *
 648     * Difference b/w Solaris PT_NOTE and Linux/BSD PT_NOTE:
 649     *
 650     *     In Solaris there are two PT_NOTE segments the first PT_NOTE (if present)
 651     *     contains /proc structs in the pre-2.6 unstructured /proc format. the last
 652     *     PT_NOTE has data in new /proc format.
 653     *
 654     *     In Solaris, there is only one pstatus (process status). pstatus contains
 655     *     integer register set among other stuff. For each LWP, we have one lwpstatus
 656     *     entry that has integer regset for that LWP.
 657     *
 658     *     Linux threads are actually 'clone'd processes. To support core analysis
 659     *     of "multithreaded" process, Linux creates more than one pstatus (called
 660     *     "prstatus") entry in PT_NOTE. Each prstatus entry has integer regset for one
 661     *     "thread". Please refer to Linux kernel src file 'fs/binfmt_elf.c', in particular
 662     *     function "elf_core_dump".
 663     */
 664 
 665     for (core_php = phbuf, i = 0; i < core_ehdr->e_phnum; i++) {
 666       switch (core_php->p_type) {
 667          case PT_NOTE:
 668             if (core_handle_note(ph, core_php) != true) {
 669               goto err;
 670             }
 671             break;
 672 
 673          case PT_LOAD: {
 674             if (core_php->p_filesz != 0) {
 675                if (add_map_info(ph, ph->core->core_fd, core_php->p_offset,
 676                   core_php->p_vaddr, core_php->p_filesz) == NULL) goto err;
 677             }
 678             break;
 679          }
 680       }
 681 
 682       core_php++;
 683    }
 684 
 685    free(phbuf);
 686    return true;
 687 err:
 688    free(phbuf);
 689    return false;
 690 }
 691 
 692 // read segments of a shared object
 693 static bool read_lib_segments(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* lib_ehdr, uintptr_t lib_base) {
 694   int i = 0;
 695   ELF_PHDR* phbuf;
 696   ELF_PHDR* lib_php = NULL;
 697 
 698   int page_size = sysconf(_SC_PAGE_SIZE);
 699 
 700   if ((phbuf = read_program_header_table(lib_fd, lib_ehdr)) == NULL) {
 701     return false;
 702   }
 703 
 704   // we want to process only PT_LOAD segments that are not writable.
 705   // i.e., text segments. The read/write/exec (data) segments would
 706   // have been already added from core file segments.
 707   for (lib_php = phbuf, i = 0; i < lib_ehdr->e_phnum; i++) {
 708     if ((lib_php->p_type == PT_LOAD) && !(lib_php->p_flags & PF_W) && (lib_php->p_filesz != 0)) {
 709 
 710       uintptr_t target_vaddr = lib_php->p_vaddr + lib_base;
 711       map_info *existing_map = core_lookup(ph, target_vaddr);
 712 
 713       if (existing_map == NULL){
 714         if (add_map_info(ph, lib_fd, lib_php->p_offset,
 715                           target_vaddr, lib_php->p_memsz) == NULL) {
 716           goto err;
 717         }
 718       } else {
 719         // Coredump stores value of p_memsz elf field
 720         // rounded up to page boundary.
 721 
 722         if ((existing_map->memsz != page_size) &&
 723             (existing_map->fd != lib_fd) &&
 724             (ROUNDUP(existing_map->memsz, page_size) != ROUNDUP(lib_php->p_memsz, page_size))) {
 725 
 726           print_debug("address conflict @ 0x%lx (existing map size = %ld, size = %ld, flags = %d)\n",
 727                         target_vaddr, existing_map->memsz, lib_php->p_memsz, lib_php->p_flags);
 728           goto err;
 729         }
 730 
 731         /* replace PT_LOAD segment with library segment */
 732         print_debug("overwrote with new address mapping (memsz %ld -> %ld)\n",
 733                      existing_map->memsz, ROUNDUP(lib_php->p_memsz, page_size));
 734 
 735         existing_map->fd = lib_fd;
 736         existing_map->offset = lib_php->p_offset;
 737         existing_map->memsz = ROUNDUP(lib_php->p_memsz, page_size);
 738       }
 739     }
 740 
 741     lib_php++;
 742   }
 743 
 744   free(phbuf);
 745   return true;
 746 err:
 747   free(phbuf);
 748   return false;
 749 }
 750 
 751 // process segments from interpreter (ld.so or ld-linux.so)
 752 static bool read_interp_segments(struct ps_prochandle* ph) {
 753   ELF_EHDR interp_ehdr;
 754 
 755   if (read_elf_header(ph->core->interp_fd, &interp_ehdr) != true) {
 756     print_debug("interpreter is not a valid ELF file\n");
 757     return false;
 758   }
 759 
 760   if (read_lib_segments(ph, ph->core->interp_fd, &interp_ehdr, ph->core->ld_base_addr) != true) {
 761     print_debug("can't read segments of interpreter\n");
 762     return false;
 763   }
 764 
 765   return true;
 766 }
 767 
 768 // process segments of a a.out
 769 static bool read_exec_segments(struct ps_prochandle* ph, ELF_EHDR* exec_ehdr) {
 770   int i = 0;
 771   ELF_PHDR* phbuf = NULL;
 772   ELF_PHDR* exec_php = NULL;
 773 
 774   if ((phbuf = read_program_header_table(ph->core->exec_fd, exec_ehdr)) == NULL) {
 775     return false;
 776   }
 777 
 778   for (exec_php = phbuf, i = 0; i < exec_ehdr->e_phnum; i++) {
 779     switch (exec_php->p_type) {
 780 
 781       // add mappings for PT_LOAD segments
 782     case PT_LOAD: {
 783       // add only non-writable segments of non-zero filesz
 784       if (!(exec_php->p_flags & PF_W) && exec_php->p_filesz != 0) {
 785         if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz) == NULL) goto err;
 786       }
 787       break;
 788     }
 789 
 790     // read the interpreter and it's segments
 791     case PT_INTERP: {
 792       char interp_name[BUF_SIZE + 1];
 793 
 794       // BUF_SIZE is PATH_MAX + NAME_MAX + 1.
 795       if (exec_php->p_filesz > BUF_SIZE) {
 796         goto err;
 797       }
 798       if (pread(ph->core->exec_fd, interp_name,
 799                 exec_php->p_filesz, exec_php->p_offset) != exec_php->p_filesz) {
 800         print_debug("Unable to read in the ELF interpreter\n");
 801         goto err;
 802       }
 803       interp_name[exec_php->p_filesz] = '\0';
 804       print_debug("ELF interpreter %s\n", interp_name);
 805       // read interpreter segments as well
 806       if ((ph->core->interp_fd = pathmap_open(interp_name)) < 0) {
 807         print_debug("can't open runtime loader\n");
 808         goto err;
 809       }
 810       break;
 811     }
 812 
 813     // from PT_DYNAMIC we want to read address of first link_map addr
 814     case PT_DYNAMIC: {
 815       if (exec_ehdr->e_type == ET_EXEC) {
 816         ph->core->dynamic_addr = exec_php->p_vaddr;
 817       } else { // ET_DYN
 818         // dynamic_addr has entry point of executable.
 819         // Thus we should substract it.
 820         ph->core->dynamic_addr += exec_php->p_vaddr - exec_ehdr->e_entry;
 821       }
 822       print_debug("address of _DYNAMIC is 0x%lx\n", ph->core->dynamic_addr);
 823       break;
 824     }
 825 
 826     } // switch
 827     exec_php++;
 828   } // for
 829 
 830   free(phbuf);
 831   return true;
 832  err:
 833   free(phbuf);
 834   return false;
 835 }
 836 
 837 
 838 #define FIRST_LINK_MAP_OFFSET offsetof(struct r_debug,  r_map)
 839 #define LD_BASE_OFFSET        offsetof(struct r_debug,  r_ldbase)
 840 #define LINK_MAP_ADDR_OFFSET  offsetof(struct link_map, l_addr)
 841 #define LINK_MAP_NAME_OFFSET  offsetof(struct link_map, l_name)
 842 #define LINK_MAP_NEXT_OFFSET  offsetof(struct link_map, l_next)
 843 
 844 // read shared library info from runtime linker's data structures.
 845 // This work is done by librtlb_db in Solaris
 846 static bool read_shared_lib_info(struct ps_prochandle* ph) {
 847   uintptr_t addr = ph->core->dynamic_addr;
 848   uintptr_t debug_base;
 849   uintptr_t first_link_map_addr;
 850   uintptr_t ld_base_addr;
 851   uintptr_t link_map_addr;
 852   uintptr_t lib_base_diff;
 853   uintptr_t lib_base;
 854   uintptr_t lib_name_addr;
 855   char lib_name[BUF_SIZE];
 856   ELF_DYN dyn;
 857   ELF_EHDR elf_ehdr;
 858   int lib_fd;
 859 
 860   // _DYNAMIC has information of the form
 861   //         [tag] [data] [tag] [data] .....
 862   // Both tag and data are pointer sized.
 863   // We look for dynamic info with DT_DEBUG. This has shared object info.
 864   // refer to struct r_debug in link.h
 865 
 866   dyn.d_tag = DT_NULL;
 867   while (dyn.d_tag != DT_DEBUG) {
 868     if (ps_pdread(ph, (psaddr_t) addr, &dyn, sizeof(ELF_DYN)) != PS_OK) {
 869       print_debug("can't read debug info from _DYNAMIC\n");
 870       return false;
 871     }
 872     addr += sizeof(ELF_DYN);
 873   }
 874 
 875   // we have got Dyn entry with DT_DEBUG
 876   debug_base = dyn.d_un.d_ptr;
 877   // at debug_base we have struct r_debug. This has first link map in r_map field
 878   if (ps_pdread(ph, (psaddr_t) debug_base + FIRST_LINK_MAP_OFFSET,
 879                  &first_link_map_addr, sizeof(uintptr_t)) != PS_OK) {
 880     print_debug("can't read first link map address\n");
 881     return false;
 882   }
 883 
 884   // read ld_base address from struct r_debug
 885   if (ps_pdread(ph, (psaddr_t) debug_base + LD_BASE_OFFSET, &ld_base_addr,
 886                  sizeof(uintptr_t)) != PS_OK) {
 887     print_debug("can't read ld base address\n");
 888     return false;
 889   }
 890   ph->core->ld_base_addr = ld_base_addr;
 891 
 892   print_debug("interpreter base address is 0x%lx\n", ld_base_addr);
 893 
 894   // now read segments from interp (i.e ld.so or ld-linux.so or ld-elf.so)
 895   if (read_interp_segments(ph) != true) {
 896       return false;
 897   }
 898 
 899   // after adding interpreter (ld.so) mappings sort again
 900   if (sort_map_array(ph) != true) {
 901     return false;
 902   }
 903 
 904    print_debug("first link map is at 0x%lx\n", first_link_map_addr);
 905 
 906    link_map_addr = first_link_map_addr;
 907    while (link_map_addr != 0) {
 908       // read library base address of the .so. Note that even though <sys/link.h> calls
 909       // link_map->l_addr as "base address",  this is * not * really base virtual
 910       // address of the shared object. This is actually the difference b/w the virtual
 911       // address mentioned in shared object and the actual virtual base where runtime
 912       // linker loaded it. We use "base diff" in read_lib_segments call below.
 913 
 914       if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_ADDR_OFFSET,
 915                    &lib_base_diff, sizeof(uintptr_t)) != PS_OK) {
 916          print_debug("can't read shared object base address diff\n");
 917          return false;
 918       }
 919 
 920       // read address of the name
 921       if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NAME_OFFSET,
 922                     &lib_name_addr, sizeof(uintptr_t)) != PS_OK) {
 923          print_debug("can't read address of shared object name\n");
 924          return false;
 925       }
 926 
 927       // read name of the shared object
 928       lib_name[0] = '\0';
 929       if (lib_name_addr != 0 &&
 930           read_string(ph, (uintptr_t) lib_name_addr, lib_name, sizeof(lib_name)) != true) {
 931          print_debug("can't read shared object name\n");
 932          // don't let failure to read the name stop opening the file.  If something is really wrong
 933          // it will fail later.
 934       }
 935 
 936       if (lib_name[0] != '\0') {
 937          // ignore empty lib names
 938          lib_fd = pathmap_open(lib_name);
 939 
 940          if (lib_fd < 0) {
 941             print_debug("can't open shared object %s\n", lib_name);
 942             // continue with other libraries...
 943          } else {
 944             if (read_elf_header(lib_fd, &elf_ehdr)) {
 945                lib_base = lib_base_diff + find_base_address(lib_fd, &elf_ehdr);
 946                print_debug("reading library %s @ 0x%lx [ 0x%lx ]\n",
 947                            lib_name, lib_base, lib_base_diff);
 948                // while adding library mappings we need to use "base difference".
 949                if (! read_lib_segments(ph, lib_fd, &elf_ehdr, lib_base_diff)) {
 950                   print_debug("can't read shared object's segments\n");
 951                   close(lib_fd);
 952                   return false;
 953                }
 954                add_lib_info_fd(ph, lib_name, lib_fd, lib_base);
 955                // Map info is added for the library (lib_name) so
 956                // we need to re-sort it before calling the p_pdread.
 957                if (sort_map_array(ph) != true)
 958                   return false;
 959             } else {
 960                print_debug("can't read ELF header for shared object %s\n", lib_name);
 961                close(lib_fd);
 962                // continue with other libraries...
 963             }
 964          }
 965       }
 966 
 967     // read next link_map address
 968     if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NEXT_OFFSET,
 969                    &link_map_addr, sizeof(uintptr_t)) != PS_OK) {
 970       print_debug("can't read next link in link_map\n");
 971       return false;
 972     }
 973   }
 974 
 975   return true;
 976 }
 977 
 978 // the one and only one exposed stuff from this file
 979 JNIEXPORT struct ps_prochandle* JNICALL
 980 Pgrab_core(const char* exec_file, const char* core_file) {
 981   ELF_EHDR core_ehdr;
 982   ELF_EHDR exec_ehdr;
 983   ELF_EHDR lib_ehdr;
 984 
 985   struct ps_prochandle* ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle));
 986   if (ph == NULL) {
 987     print_debug("can't allocate ps_prochandle\n");
 988     return NULL;
 989   }
 990 
 991   if ((ph->core = (struct core_data*) calloc(1, sizeof(struct core_data))) == NULL) {
 992     free(ph);
 993     print_debug("can't allocate ps_prochandle\n");
 994     return NULL;
 995   }
 996 
 997   // initialize ph
 998   ph->ops = &core_ops;
 999   ph->core->core_fd   = -1;
1000   ph->core->exec_fd   = -1;
1001   ph->core->interp_fd = -1;
1002 
1003   // open the core file
1004   if ((ph->core->core_fd = open(core_file, O_RDONLY)) < 0) {
1005     print_debug("can't open core file\n");
1006     goto err;
1007   }
1008 
1009   // read core file ELF header
1010   if (read_elf_header(ph->core->core_fd, &core_ehdr) != true || core_ehdr.e_type != ET_CORE) {
1011     print_debug("core file is not a valid ELF ET_CORE file\n");
1012     goto err;
1013   }
1014 
1015   if ((ph->core->exec_fd = open(exec_file, O_RDONLY)) < 0) {
1016     print_debug("can't open executable file\n");
1017     goto err;
1018   }
1019 
1020   if (read_elf_header(ph->core->exec_fd, &exec_ehdr) != true ||
1021       ((exec_ehdr.e_type != ET_EXEC) && (exec_ehdr.e_type != ET_DYN))) {
1022     print_debug("executable file is not a valid ELF file\n");
1023     goto err;
1024   }
1025 
1026   // process core file segments
1027   if (read_core_segments(ph, &core_ehdr) != true) {
1028     goto err;
1029   }
1030 
1031   // process exec file segments
1032   if (read_exec_segments(ph, &exec_ehdr) != true) {
1033     goto err;
1034   }
1035 
1036   // exec file is also treated like a shared object for symbol search
1037   if (add_lib_info_fd(ph, exec_file, ph->core->exec_fd,
1038                       (uintptr_t)0 + find_base_address(ph->core->exec_fd, &exec_ehdr)) == NULL) {
1039     goto err;
1040   }
1041 
1042   // allocate and sort maps into map_array, we need to do this
1043   // here because read_shared_lib_info needs to read from debuggee
1044   // address space
1045   if (sort_map_array(ph) != true) {
1046     goto err;
1047   }
1048 
1049   if (read_shared_lib_info(ph) != true) {
1050     goto err;
1051   }
1052 
1053   // sort again because we have added more mappings from shared objects
1054   if (sort_map_array(ph) != true) {
1055     goto err;
1056   }
1057 
1058   if (init_classsharing_workaround(ph) != true) {
1059     goto err;
1060   }
1061 
1062   return ph;
1063 
1064 err:
1065   Prelease(ph);
1066   return NULL;
1067 }
--- EOF ---