1 /*
   2  * Copyright (c) 2019, 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> // just include something, or else solaris compiler will complain that this file is empty
  26 
  27 #if defined(LINUX) || defined(__APPLE__)
  28 #include <unistd.h>
  29 #include <fcntl.h>
  30 #include <string.h>
  31 #include <stdlib.h>
  32 #include <stddef.h>
  33 #ifdef LINUX
  34 #include <elf.h>
  35 #include <link.h>
  36 #include "proc_service.h"
  37 #include "salibelf.h"
  38 #endif
  39 #include "libproc_impl.h"
  40 #include "cds.h"
  41 
  42 #ifdef __APPLE__
  43 #include "sun_jvm_hotspot_debugger_amd64_AMD64ThreadContext.h"
  44 #endif
  45 
  46 #ifdef LINUX
  47 // I have no idea why this function is called ps_pread() on macos but ps_pdread on linux.
  48 #define ps_pread ps_pdread
  49 #endif
  50 
  51 // Common code shared between linux/native/libsaproc/ps_core.c and macosx/native/libsaproc/ps_core.c
  52 
  53 //----------------------------------------------------------------------
  54 // ps_prochandle cleanup helper functions
  55 
  56 // close all file descriptors
  57 static void close_files(struct ps_prochandle* ph) {
  58   lib_info* lib = NULL;
  59 
  60   // close core file descriptor
  61   if (ph->core->core_fd >= 0)
  62     close(ph->core->core_fd);
  63 
  64   // close exec file descriptor
  65   if (ph->core->exec_fd >= 0)
  66     close(ph->core->exec_fd);
  67 
  68   // close interp file descriptor
  69   if (ph->core->interp_fd >= 0)
  70     close(ph->core->interp_fd);
  71 
  72   // close class share archive file
  73   if (ph->core->classes_jsa_fd >= 0)
  74     close(ph->core->classes_jsa_fd);
  75 
  76   // close all library file descriptors
  77   lib = ph->libs;
  78   while (lib) {
  79     int fd = lib->fd;
  80     if (fd >= 0 && fd != ph->core->exec_fd) {
  81       close(fd);
  82     }
  83     lib = lib->next;
  84   }
  85 }
  86 
  87 // clean all map_info stuff
  88 static void destroy_map_info(struct ps_prochandle* ph) {
  89   map_info* map = ph->core->maps;
  90   while (map) {
  91     map_info* next = map->next;
  92     free(map);
  93     map = next;
  94   }
  95 
  96   if (ph->core->map_array) {
  97     free(ph->core->map_array);
  98   }
  99 
 100   // Part of the class sharing workaround
 101   map = ph->core->class_share_maps;
 102   while (map) {
 103     map_info* next = map->next;
 104     free(map);
 105     map = next;
 106   }
 107 }
 108 
 109 // ps_prochandle operations
 110 void core_release(struct ps_prochandle* ph) {
 111   if (ph->core) {
 112     close_files(ph);
 113     destroy_map_info(ph);
 114     free(ph->core);
 115   }
 116 }
 117 
 118 static map_info* allocate_init_map(int fd, off_t offset, uintptr_t vaddr, size_t memsz) {
 119   map_info* map;
 120   if ( (map = (map_info*) calloc(1, sizeof(map_info))) == NULL) {
 121     print_debug("can't allocate memory for map_info\n");
 122     return NULL;
 123   }
 124 
 125   // initialize map
 126   map->fd     = fd;
 127   map->offset = offset;
 128   map->vaddr  = vaddr;
 129   map->memsz  = memsz;
 130   return map;
 131 }
 132 
 133 // add map info with given fd, offset, vaddr and memsz
 134 map_info* add_map_info(struct ps_prochandle* ph, int fd, off_t offset,
 135                        uintptr_t vaddr, size_t memsz) {
 136   map_info* map;
 137   if ((map = allocate_init_map(fd, offset, vaddr, memsz)) == NULL) {
 138     return NULL;
 139   }
 140 
 141   // add this to map list
 142   map->next  = ph->core->maps;
 143   ph->core->maps   = map;
 144   ph->core->num_maps++;
 145 
 146   return map;
 147 }
 148 
 149 // Part of the class sharing workaround
 150 static map_info* add_class_share_map_info(struct ps_prochandle* ph, off_t offset,
 151                              uintptr_t vaddr, size_t memsz) {
 152   map_info* map;
 153   if ((map = allocate_init_map(ph->core->classes_jsa_fd,
 154                                offset, vaddr, memsz)) == NULL) {
 155     return NULL;
 156   }
 157 
 158   map->next = ph->core->class_share_maps;
 159   ph->core->class_share_maps = map;
 160   return map;
 161 }
 162 
 163 // Return the map_info for the given virtual address.  We keep a sorted
 164 // array of pointers in ph->map_array, so we can binary search.
 165 map_info* core_lookup(struct ps_prochandle *ph, uintptr_t addr) {
 166   int mid, lo = 0, hi = ph->core->num_maps - 1;
 167   map_info *mp;
 168 
 169   while (hi - lo > 1) {
 170     mid = (lo + hi) / 2;
 171     if (addr >= ph->core->map_array[mid]->vaddr) {
 172       lo = mid;
 173     } else {
 174       hi = mid;
 175     }
 176   }
 177 
 178   if (addr < ph->core->map_array[hi]->vaddr) {
 179     mp = ph->core->map_array[lo];
 180   } else {
 181     mp = ph->core->map_array[hi];
 182   }
 183 
 184   if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) {
 185     return (mp);
 186   }
 187 
 188 
 189   // Part of the class sharing workaround
 190   // Unfortunately, we have no way of detecting -Xshare state.
 191   // Check out the share maps atlast, if we don't find anywhere.
 192   // This is done this way so to avoid reading share pages
 193   // ahead of other normal maps. For eg. with -Xshare:off we don't
 194   // want to prefer class sharing data to data from core.
 195   mp = ph->core->class_share_maps;
 196   if (mp) {
 197     print_debug("can't locate map_info at 0x%lx, trying class share maps\n", addr);
 198   }
 199   while (mp) {
 200     if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) {
 201       print_debug("located map_info at 0x%lx from class share maps\n", addr);
 202       return (mp);
 203     }
 204     mp = mp->next;
 205   }
 206 
 207   print_debug("can't locate map_info at 0x%lx\n", addr);
 208   return (NULL);
 209 }
 210 
 211 //---------------------------------------------------------------
 212 // Part of the class sharing workaround:
 213 //
 214 // With class sharing, pages are mapped from classes.jsa file.
 215 // The read-only class sharing pages are mapped as MAP_SHARED,
 216 // PROT_READ pages. These pages are not dumped into core dump.
 217 // With this workaround, these pages are read from classes.jsa.
 218 
 219 static bool read_jboolean(struct ps_prochandle* ph, uintptr_t addr, jboolean* pvalue) {
 220   jboolean i;
 221   if (ps_pread(ph, (psaddr_t) addr, &i, sizeof(i)) == PS_OK) {
 222     *pvalue = i;
 223     return true;
 224   } else {
 225     return false;
 226   }
 227 }
 228 
 229 static bool read_pointer(struct ps_prochandle* ph, uintptr_t addr, uintptr_t* pvalue) {
 230   uintptr_t uip;
 231   if (ps_pread(ph, (psaddr_t) addr, (char *)&uip, sizeof(uip)) == PS_OK) {
 232     *pvalue = uip;
 233     return true;
 234   } else {
 235     return false;
 236   }
 237 }
 238 
 239 // used to read strings from debuggee
 240 bool read_string(struct ps_prochandle* ph, uintptr_t addr, char* buf, size_t size) {
 241   size_t i = 0;
 242   char  c = ' ';
 243 
 244   while (c != '\0') {
 245     if (ps_pread(ph, (psaddr_t) addr, &c, sizeof(char)) != PS_OK) {
 246       return false;
 247     }
 248     if (i < size - 1) {
 249       buf[i] = c;
 250     } else {
 251       // smaller buffer
 252       return false;
 253     }
 254     i++; addr++;
 255   }
 256   buf[i] = '\0';
 257   return true;
 258 }
 259 
 260 #ifdef LINUX
 261 // mangled name of Arguments::SharedArchivePath
 262 #define SHARED_ARCHIVE_PATH_SYM "_ZN9Arguments17SharedArchivePathE"
 263 #define USE_SHARED_SPACES_SYM "UseSharedSpaces"
 264 #define LIBJVM_NAME "/libjvm.so"
 265 #endif
 266 
 267 #ifdef __APPLE__
 268 // mangled name of Arguments::SharedArchivePath
 269 #define SHARED_ARCHIVE_PATH_SYM "__ZN9Arguments17SharedArchivePathE"
 270 #define USE_SHARED_SPACES_SYM "_UseSharedSpaces"
 271 #define LIBJVM_NAME "/libjvm.dylib"
 272 #endif
 273 
 274 bool init_classsharing_workaround(struct ps_prochandle* ph) {
 275   lib_info* lib = ph->libs;
 276   while (lib != NULL) {
 277     // we are iterating over shared objects from the core dump. look for
 278     // libjvm.so.
 279     const char *jvm_name = 0;
 280     if ((jvm_name = strstr(lib->name, LIBJVM_NAME)) != 0) {
 281       char classes_jsa[PATH_MAX];
 282       CDSFileMapHeaderBase header;
 283       int fd = -1;
 284       uintptr_t base = 0, useSharedSpacesAddr = 0;
 285       uintptr_t sharedArchivePathAddrAddr = 0, sharedArchivePathAddr = 0;
 286       jboolean useSharedSpaces = 0;
 287       int m;
 288       size_t n;
 289 
 290       memset(classes_jsa, 0, sizeof(classes_jsa));
 291       jvm_name = lib->name;
 292       useSharedSpacesAddr = lookup_symbol(ph, jvm_name, USE_SHARED_SPACES_SYM);
 293       if (useSharedSpacesAddr == 0) {
 294         print_debug("can't lookup 'UseSharedSpaces' flag\n");
 295         return false;
 296       }
 297 
 298       // Hotspot vm types are not exported to build this library. So
 299       // using equivalent type jboolean to read the value of
 300       // UseSharedSpaces which is same as hotspot type "bool".
 301       if (read_jboolean(ph, useSharedSpacesAddr, &useSharedSpaces) != true) {
 302         print_debug("can't read the value of 'UseSharedSpaces' flag\n");
 303         return false;
 304       }
 305 
 306       if ((int)useSharedSpaces == 0) {
 307         print_debug("UseSharedSpaces is false, assuming -Xshare:off!\n");
 308         return true;
 309       }
 310 
 311       sharedArchivePathAddrAddr = lookup_symbol(ph, jvm_name, SHARED_ARCHIVE_PATH_SYM);
 312       if (sharedArchivePathAddrAddr == 0) {
 313         print_debug("can't lookup shared archive path symbol\n");
 314         return false;
 315       }
 316 
 317       if (read_pointer(ph, sharedArchivePathAddrAddr, &sharedArchivePathAddr) != true) {
 318         print_debug("can't read shared archive path pointer\n");
 319         return false;
 320       }
 321 
 322       if (read_string(ph, sharedArchivePathAddr, classes_jsa, sizeof(classes_jsa)) != true) {
 323         print_debug("can't read shared archive path value\n");
 324         return false;
 325       }
 326 
 327       print_debug("looking for %s\n", classes_jsa);
 328       // open the class sharing archive file
 329       fd = pathmap_open(classes_jsa);
 330       if (fd < 0) {
 331         print_debug("can't open %s!\n", classes_jsa);
 332         ph->core->classes_jsa_fd = -1;
 333         return false;
 334       } else {
 335         print_debug("opened %s\n", classes_jsa);
 336       }
 337 
 338       // read CDSFileMapHeaderBase from the file
 339       memset(&header, 0, sizeof(CDSFileMapHeaderBase));
 340       if ((n = read(fd, &header, sizeof(CDSFileMapHeaderBase)))
 341            != sizeof(CDSFileMapHeaderBase)) {
 342         print_debug("can't read shared archive file map header from %s\n", classes_jsa);
 343         close(fd);
 344         return false;
 345       }
 346 
 347       // check file magic
 348       if (header._magic != CDS_ARCHIVE_MAGIC) {
 349         print_debug("%s has bad shared archive file magic number 0x%x, expecting 0x%x\n",
 350                     classes_jsa, header._magic, CDS_ARCHIVE_MAGIC);
 351         close(fd);
 352         return false;
 353       }
 354 
 355       // check version
 356       if (header._version != CURRENT_CDS_ARCHIVE_VERSION) {
 357         print_debug("%s has wrong shared archive file version %d, expecting %d\n",
 358                      classes_jsa, header._version, CURRENT_CDS_ARCHIVE_VERSION);
 359         close(fd);
 360         return false;
 361       }
 362 
 363       ph->core->classes_jsa_fd = fd;
 364       // add read-only maps from classes.jsa to the list of maps
 365       for (m = 0; m < NUM_CDS_REGIONS; m++) {
 366         if (header._space[m]._read_only) {
 367           // With *some* linux versions, the core file doesn't include read-only mmap'ed
 368           // files regions, so let's add them here. This is harmless if the core file also
 369           // include these regions.
 370           base = (uintptr_t) header._space[m]._addr._base;
 371           // no need to worry about the fractional pages at-the-end.
 372           // possible fractional pages are handled by core_read_data.
 373           add_class_share_map_info(ph, (off_t) header._space[m]._file_offset,
 374                                    base, (size_t) header._space[m]._used);
 375           print_debug("added a share archive map at 0x%lx\n", base);
 376         }
 377       }
 378       return true;
 379    }
 380    lib = lib->next;
 381   }
 382   return true;
 383 }
 384 
 385 #endif // defined(LINUX) || defined(__APPLE__)