jdk8-mips64-public/hotspot: agent/src/os/linux/ps

agent/src/os/linux/ps_core.c@da91efe96a93 (annotated)

agent/src/os/linux/ps_core.c

Sat, 01 Sep 2012 13:25:18 -0400

author: coleenp
date: Sat, 01 Sep 2012 13:25:18 -0400
changeset 4037: da91efe96a93
parent 3722: 29ee40a082d3
child 4709: 255c0a4cb4eb
permissions: -rw-r--r--

6964458: Reimplement class meta-data storage to use native memory
Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes
Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland
Contributed-by: jmasa <jon.masamitsu@oracle.com>, stefank <stefan.karlsson@oracle.com>, mgerdin <mikael.gerdin@oracle.com>, never <tom.rodriguez@oracle.com>

 /*
  * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include <jni.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <string.h>
 #include <stdlib.h>
 #include <stddef.h>
 #include <elf.h>
 #include <link.h>
 #include "libproc_impl.h"
 #include "salibelf.h"
 // This file has the libproc implementation to read core files.
 // For live processes, refer to ps_proc.c. Portions of this is adapted
 // /modelled after Solaris libproc.so (in particular Pcore.c)
 //----------------------------------------------------------------------
 // ps_prochandle cleanup helper functions
 // close all file descriptors
 static void close_elf_files(struct ps_prochandle* ph) {
    lib_info* lib = NULL;
    // close core file descriptor
    if (ph->core->core_fd >= 0)
      close(ph->core->core_fd);
    // close exec file descriptor
    if (ph->core->exec_fd >= 0)
      close(ph->core->exec_fd);
    // close interp file descriptor
    if (ph->core->interp_fd >= 0)
      close(ph->core->interp_fd);
    // close class share archive file
    if (ph->core->classes_jsa_fd >= 0)
      close(ph->core->classes_jsa_fd);
    // close all library file descriptors
    lib = ph->libs;
    while (lib) {
       int fd = lib->fd;
       if (fd >= 0 && fd != ph->core->exec_fd) close(fd);
       lib = lib->next;
    }
 }
 // clean all map_info stuff
 static void destroy_map_info(struct ps_prochandle* ph) {
   map_info* map = ph->core->maps;
   while (map) {
      map_info* next = map->next;
      free(map);
      map = next;
   }
   if (ph->core->map_array) {
      free(ph->core->map_array);
   }
   // Part of the class sharing workaround
   map = ph->core->class_share_maps;
   while (map) {
      map_info* next = map->next;
      free(map);
      map = next;
   }
 }
 // ps_prochandle operations
 static void core_release(struct ps_prochandle* ph) {
    if (ph->core) {
       close_elf_files(ph);
       destroy_map_info(ph);
       free(ph->core);
    }
 }
 static map_info* allocate_init_map(int fd, off_t offset, uintptr_t vaddr, size_t memsz) {
    map_info* map;
    if ( (map = (map_info*) calloc(1, sizeof(map_info))) == NULL) {
       print_debug("can't allocate memory for map_info\n");
       return NULL;
    }
    // initialize map
    map->fd     = fd;
    map->offset = offset;
    map->vaddr  = vaddr;
    map->memsz  = memsz;
    return map;
 }
 // add map info with given fd, offset, vaddr and memsz
 static map_info* add_map_info(struct ps_prochandle* ph, int fd, off_t offset,
                              uintptr_t vaddr, size_t memsz) {
    map_info* map;
    if ((map = allocate_init_map(fd, offset, vaddr, memsz)) == NULL) {
       return NULL;
    }
    // add this to map list
    map->next  = ph->core->maps;
    ph->core->maps   = map;
    ph->core->num_maps++;
    return map;
 }
 // Part of the class sharing workaround
 static map_info* add_class_share_map_info(struct ps_prochandle* ph, off_t offset,
                              uintptr_t vaddr, size_t memsz) {
    map_info* map;
    if ((map = allocate_init_map(ph->core->classes_jsa_fd,
                                 offset, vaddr, memsz)) == NULL) {
       return NULL;
    }
    map->next = ph->core->class_share_maps;
    ph->core->class_share_maps = map;
 }
 // Return the map_info for the given virtual address.  We keep a sorted
 // array of pointers in ph->map_array, so we can binary search.
 static map_info* core_lookup(struct ps_prochandle *ph, uintptr_t addr)
 {
    int mid, lo = 0, hi = ph->core->num_maps - 1;
    map_info *mp;
    while (hi - lo > 1) {
      mid = (lo + hi) / 2;
       if (addr >= ph->core->map_array[mid]->vaddr)
          lo = mid;
       else
          hi = mid;
    }
    if (addr < ph->core->map_array[hi]->vaddr)
       mp = ph->core->map_array[lo];
    else
       mp = ph->core->map_array[hi];
    if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz)
       return (mp);
    // Part of the class sharing workaround
    // Unfortunately, we have no way of detecting -Xshare state.
    // Check out the share maps atlast, if we don't find anywhere.
    // This is done this way so to avoid reading share pages
    // ahead of other normal maps. For eg. with -Xshare:off we don't
    // want to prefer class sharing data to data from core.
    mp = ph->core->class_share_maps;
    if (mp) {
       print_debug("can't locate map_info at 0x%lx, trying class share maps\n",
              addr);
    }
    while (mp) {
       if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) {
          print_debug("located map_info at 0x%lx from class share maps\n",
                   addr);
          return (mp);
       }
       mp = mp->next;
    }
    print_debug("can't locate map_info at 0x%lx\n", addr);
    return (NULL);
 }
 //---------------------------------------------------------------
 // Part of the class sharing workaround:
 //
 // With class sharing, pages are mapped from classes[_g].jsa file.
 // The read-only class sharing pages are mapped as MAP_SHARED,
 // PROT_READ pages. These pages are not dumped into core dump.
 // With this workaround, these pages are read from classes[_g].jsa.
 // FIXME: !HACK ALERT!
 // The format of sharing achive file header is needed to read shared heap
 // file mappings. For now, I am hard coding portion of FileMapHeader here.
 // Refer to filemap.hpp.
 // FileMapHeader describes the shared space data in the file to be
 // mapped.  This structure gets written to a file.  It is not a class,
 // so that the compilers don't add any compiler-private data to it.
 #define NUM_SHARED_MAPS 4
 // Refer to FileMapInfo::_current_version in filemap.hpp
 #define CURRENT_ARCHIVE_VERSION 1
 struct FileMapHeader {
   int   _magic;              // identify file type.
   int   _version;            // (from enum, above.)
   size_t _alignment;         // how shared archive should be aligned
   struct space_info {
     int    _file_offset;     // sizeof(this) rounded to vm page size
     char*  _base;            // copy-on-write base address
     size_t _capacity;        // for validity checking
     size_t _used;            // for setting space top on read
     // 4991491 NOTICE These are C++ bool's in filemap.hpp and must match up with
     // the C type matching the C++ bool type on any given platform. For
     // Hotspot on Linux we assume the corresponding C type is char but
     // licensees on Linux versions may need to adjust the type of these fields.
     char   _read_only;       // read only space?
     char   _allow_exec;      // executable code in space?
   } _space[NUM_SHARED_MAPS];
   // Ignore the rest of the FileMapHeader. We don't need those fields here.
 };
 static bool read_jboolean(struct ps_prochandle* ph, uintptr_t addr, jboolean* pvalue) {
    jboolean i;
    if (ps_pdread(ph, (psaddr_t) addr, &i, sizeof(i)) == PS_OK) {
       *pvalue = i;
       return true;
    } else {
       return false;
    }
 }
 static bool read_pointer(struct ps_prochandle* ph, uintptr_t addr, uintptr_t* pvalue) {
    uintptr_t uip;
    if (ps_pdread(ph, (psaddr_t) addr, &uip, sizeof(uip)) == PS_OK) {
       *pvalue = uip;
       return true;
    } else {
       return false;
    }
 }
 // used to read strings from debuggee
 static bool read_string(struct ps_prochandle* ph, uintptr_t addr, char* buf, size_t size) {
    size_t i = 0;
    char  c = ' ';
    while (c != '\0') {
      if (ps_pdread(ph, (psaddr_t) addr, &c, sizeof(char)) != PS_OK)
          return false;
       if (i < size - 1)
          buf[i] = c;
       else // smaller buffer
          return false;
       i++; addr++;
    }
    buf[i] = '\0';
    return true;
 }
 #define USE_SHARED_SPACES_SYM "UseSharedSpaces"
 // mangled name of Arguments::SharedArchivePath
 #define SHARED_ARCHIVE_PATH_SYM "_ZN9Arguments17SharedArchivePathE"
 static bool init_classsharing_workaround(struct ps_prochandle* ph) {
    lib_info* lib = ph->libs;
    while (lib != NULL) {
       // we are iterating over shared objects from the core dump. look for
       // libjvm[_g].so.
       const char *jvm_name = 0;
       if ((jvm_name = strstr(lib->name, "/libjvm.so")) != 0 ||
           (jvm_name = strstr(lib->name, "/libjvm_g.so")) != 0) {
          char classes_jsa[PATH_MAX];
          struct FileMapHeader header;
          size_t n = 0;
          int fd = -1, m = 0;
          uintptr_t base = 0, useSharedSpacesAddr = 0;
          uintptr_t sharedArchivePathAddrAddr = 0, sharedArchivePathAddr = 0;
          jboolean useSharedSpaces = 0;
          map_info* mi = 0;
          memset(classes_jsa, 0, sizeof(classes_jsa));
          jvm_name = lib->name;
          useSharedSpacesAddr = lookup_symbol(ph, jvm_name, USE_SHARED_SPACES_SYM);
          if (useSharedSpacesAddr == 0) {
             print_debug("can't lookup 'UseSharedSpaces' flag\n");
             return false;
          }
          // Hotspot vm types are not exported to build this library. So
          // using equivalent type jboolean to read the value of
          // UseSharedSpaces which is same as hotspot type "bool".
          if (read_jboolean(ph, useSharedSpacesAddr, &useSharedSpaces) != true) {
             print_debug("can't read the value of 'UseSharedSpaces' flag\n");
             return false;
          }
          if ((int)useSharedSpaces == 0) {
             print_debug("UseSharedSpaces is false, assuming -Xshare:off!\n");
             return true;
          }
          sharedArchivePathAddrAddr = lookup_symbol(ph, jvm_name, SHARED_ARCHIVE_PATH_SYM);
          if (sharedArchivePathAddrAddr == 0) {
             print_debug("can't lookup shared archive path symbol\n");
             return false;
          }
          if (read_pointer(ph, sharedArchivePathAddrAddr, &sharedArchivePathAddr) != true) {
             print_debug("can't read shared archive path pointer\n");
             return false;
          }
          if (read_string(ph, sharedArchivePathAddr, classes_jsa, sizeof(classes_jsa)) != true) {
             print_debug("can't read shared archive path value\n");
             return false;
          }
          print_debug("looking for %s\n", classes_jsa);
          // open the class sharing archive file
          fd = pathmap_open(classes_jsa);
          if (fd < 0) {
             print_debug("can't open %s!\n", classes_jsa);
             ph->core->classes_jsa_fd = -1;
             return false;
          } else {
             print_debug("opened %s\n", classes_jsa);
          }
          // read FileMapHeader from the file
          memset(&header, 0, sizeof(struct FileMapHeader));
          if ((n = read(fd, &header, sizeof(struct FileMapHeader)))
               != sizeof(struct FileMapHeader)) {
             print_debug("can't read shared archive file map header from %s\n", classes_jsa);
             close(fd);
             return false;
          }
          // check file magic
          if (header._magic != 0xf00baba2) {
             print_debug("%s has bad shared archive file magic number 0x%x, expecing 0xf00baba2\n",
                         classes_jsa, header._magic);
             close(fd);
             return false;
          }
          // check version
          if (header._version != CURRENT_ARCHIVE_VERSION) {
             print_debug("%s has wrong shared archive file version %d, expecting %d\n",
                         classes_jsa, header._version, CURRENT_ARCHIVE_VERSION);
             close(fd);
             return false;
          }
          ph->core->classes_jsa_fd = fd;
          // add read-only maps from classes[_g].jsa to the list of maps
          for (m = 0; m < NUM_SHARED_MAPS; m++) {
             if (header._space[m]._read_only) {
                base = (uintptr_t) header._space[m]._base;
                // no need to worry about the fractional pages at-the-end.
                // possible fractional pages are handled by core_read_data.
                add_class_share_map_info(ph, (off_t) header._space[m]._file_offset,
                          base, (size_t) header._space[m]._used);
                print_debug("added a share archive map at 0x%lx\n", base);
             }
          }
          return true;
       }
       lib = lib->next;
    }
    return true;
 }
 //---------------------------------------------------------------------------
 // functions to handle map_info
 // Order mappings based on virtual address.  We use this function as the
 // callback for sorting the array of map_info pointers.
 static int core_cmp_mapping(const void *lhsp, const void *rhsp)
 {
    const map_info *lhs = *((const map_info **)lhsp);
    const map_info *rhs = *((const map_info **)rhsp);
    if (lhs->vaddr == rhs->vaddr)
       return (0);
    return (lhs->vaddr < rhs->vaddr ? -1 : 1);
 }
 // we sort map_info by starting virtual address so that we can do
 // binary search to read from an address.
 static bool sort_map_array(struct ps_prochandle* ph) {
    size_t num_maps = ph->core->num_maps;
    map_info* map = ph->core->maps;
    int i = 0;
    // allocate map_array
    map_info** array;
    if ( (array = (map_info**) malloc(sizeof(map_info*) * num_maps)) == NULL) {
       print_debug("can't allocate memory for map array\n");
       return false;
    }
    // add maps to array
    while (map) {
       array[i] = map;
       i++;
       map = map->next;
    }
    // sort is called twice. If this is second time, clear map array
    if (ph->core->map_array) free(ph->core->map_array);
    ph->core->map_array = array;
    // sort the map_info array by base virtual address.
    qsort(ph->core->map_array, ph->core->num_maps, sizeof (map_info*),
             core_cmp_mapping);
    // print map
    if (is_debug()) {
       int j = 0;
       print_debug("---- sorted virtual address map ----\n");
       for (j = 0; j < ph->core->num_maps; j++) {
         print_debug("base = 0x%lx\tsize = %zu\n", ph->core->map_array[j]->vaddr,
                                          ph->core->map_array[j]->memsz);
       }
    }
    return true;
 }
 #ifndef MIN
 #define MIN(x, y) (((x) < (y))? (x): (y))
 #endif
 static bool core_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
    ssize_t resid = size;
    int page_size=sysconf(_SC_PAGE_SIZE);
    while (resid != 0) {
       map_info *mp = core_lookup(ph, addr);
       uintptr_t mapoff;
       ssize_t len, rem;
       off_t off;
       int fd;
       if (mp == NULL)
          break;  /* No mapping for this address */
       fd = mp->fd;
       mapoff = addr - mp->vaddr;
       len = MIN(resid, mp->memsz - mapoff);
       off = mp->offset + mapoff;
       if ((len = pread(fd, buf, len, off)) <= 0)
          break;
       resid -= len;
       addr += len;
       buf = (char *)buf + len;
       // mappings always start at page boundary. But, may end in fractional
       // page. fill zeros for possible fractional page at the end of a mapping.
       rem = mp->memsz % page_size;
       if (rem > 0) {
          rem = page_size - rem;
          len = MIN(resid, rem);
          resid -= len;
          addr += len;
          // we are not assuming 'buf' to be zero initialized.
          memset(buf, 0, len);
          buf += len;
       }
    }
    if (resid) {
       print_debug("core read failed for %d byte(s) @ 0x%lx (%d more bytes)\n",
               size, addr, resid);
       return false;
    } else {
       return true;
    }
 }
 // null implementation for write
 static bool core_write_data(struct ps_prochandle* ph,
                              uintptr_t addr, const char *buf , size_t size) {
    return false;
 }
 static bool core_get_lwp_regs(struct ps_prochandle* ph, lwpid_t lwp_id,
                           struct user_regs_struct* regs) {
    // for core we have cached the lwp regs from NOTE section
    thread_info* thr = ph->threads;
    while (thr) {
      if (thr->lwp_id == lwp_id) {
        memcpy(regs, &thr->regs, sizeof(struct user_regs_struct));
        return true;
      }
      thr = thr->next;
    }
    return false;
 }
 static ps_prochandle_ops core_ops = {
    .release=  core_release,
    .p_pread=  core_read_data,
    .p_pwrite= core_write_data,
    .get_lwp_regs= core_get_lwp_regs
 };
 // read regs and create thread from NT_PRSTATUS entries from core file
 static bool core_handle_prstatus(struct ps_prochandle* ph, const char* buf, size_t nbytes) {
    // we have to read prstatus_t from buf
    // assert(nbytes == sizeof(prstaus_t), "size mismatch on prstatus_t");
    prstatus_t* prstat = (prstatus_t*) buf;
    thread_info* newthr;
    print_debug("got integer regset for lwp %d\n", prstat->pr_pid);
    // we set pthread_t to -1 for core dump
    if((newthr = add_thread_info(ph, (pthread_t) -1,  prstat->pr_pid)) == NULL)
       return false;
    // copy regs
    memcpy(&newthr->regs, prstat->pr_reg, sizeof(struct user_regs_struct));
    if (is_debug()) {
       print_debug("integer regset\n");
 #ifdef i386
       // print the regset
       print_debug("\teax = 0x%x\n", newthr->regs.eax);
       print_debug("\tebx = 0x%x\n", newthr->regs.ebx);
       print_debug("\tecx = 0x%x\n", newthr->regs.ecx);
       print_debug("\tedx = 0x%x\n", newthr->regs.edx);
       print_debug("\tesp = 0x%x\n", newthr->regs.esp);
       print_debug("\tebp = 0x%x\n", newthr->regs.ebp);
       print_debug("\tesi = 0x%x\n", newthr->regs.esi);
       print_debug("\tedi = 0x%x\n", newthr->regs.edi);
       print_debug("\teip = 0x%x\n", newthr->regs.eip);
 #endif
 #if defined(amd64) || defined(x86_64)
       // print the regset
       print_debug("\tr15 = 0x%lx\n", newthr->regs.r15);
       print_debug("\tr14 = 0x%lx\n", newthr->regs.r14);
       print_debug("\tr13 = 0x%lx\n", newthr->regs.r13);
       print_debug("\tr12 = 0x%lx\n", newthr->regs.r12);
       print_debug("\trbp = 0x%lx\n", newthr->regs.rbp);
       print_debug("\trbx = 0x%lx\n", newthr->regs.rbx);
       print_debug("\tr11 = 0x%lx\n", newthr->regs.r11);
       print_debug("\tr10 = 0x%lx\n", newthr->regs.r10);
       print_debug("\tr9 = 0x%lx\n", newthr->regs.r9);
       print_debug("\tr8 = 0x%lx\n", newthr->regs.r8);
       print_debug("\trax = 0x%lx\n", newthr->regs.rax);
       print_debug("\trcx = 0x%lx\n", newthr->regs.rcx);
       print_debug("\trdx = 0x%lx\n", newthr->regs.rdx);
       print_debug("\trsi = 0x%lx\n", newthr->regs.rsi);
       print_debug("\trdi = 0x%lx\n", newthr->regs.rdi);
       print_debug("\torig_rax = 0x%lx\n", newthr->regs.orig_rax);
       print_debug("\trip = 0x%lx\n", newthr->regs.rip);
       print_debug("\tcs = 0x%lx\n", newthr->regs.cs);
       print_debug("\teflags = 0x%lx\n", newthr->regs.eflags);
       print_debug("\trsp = 0x%lx\n", newthr->regs.rsp);
       print_debug("\tss = 0x%lx\n", newthr->regs.ss);
       print_debug("\tfs_base = 0x%lx\n", newthr->regs.fs_base);
       print_debug("\tgs_base = 0x%lx\n", newthr->regs.gs_base);
       print_debug("\tds = 0x%lx\n", newthr->regs.ds);
       print_debug("\tes = 0x%lx\n", newthr->regs.es);
       print_debug("\tfs = 0x%lx\n", newthr->regs.fs);
       print_debug("\tgs = 0x%lx\n", newthr->regs.gs);
 #endif
    }
    return true;
 }
 #define ROUNDUP(x, y)  ((((x)+((y)-1))/(y))*(y))
 // read NT_PRSTATUS entries from core NOTE segment
 static bool core_handle_note(struct ps_prochandle* ph, ELF_PHDR* note_phdr) {
    char* buf = NULL;
    char* p = NULL;
    size_t size = note_phdr->p_filesz;
    // we are interested in just prstatus entries. we will ignore the rest.
    // Advance the seek pointer to the start of the PT_NOTE data
    if (lseek(ph->core->core_fd, note_phdr->p_offset, SEEK_SET) == (off_t)-1) {
       print_debug("failed to lseek to PT_NOTE data\n");
       return false;
    }
    // Now process the PT_NOTE structures.  Each one is preceded by
    // an Elf{32/64}_Nhdr structure describing its type and size.
    if ( (buf = (char*) malloc(size)) == NULL) {
       print_debug("can't allocate memory for reading core notes\n");
       goto err;
    }
    // read notes into buffer
    if (read(ph->core->core_fd, buf, size) != size) {
       print_debug("failed to read notes, core file must have been truncated\n");
       goto err;
    }
    p = buf;
    while (p < buf + size) {
       ELF_NHDR* notep = (ELF_NHDR*) p;
       char* descdata  = p + sizeof(ELF_NHDR) + ROUNDUP(notep->n_namesz, 4);
       print_debug("Note header with n_type = %d and n_descsz = %u\n",
                                    notep->n_type, notep->n_descsz);
       if (notep->n_type == NT_PRSTATUS) {
          if (core_handle_prstatus(ph, descdata, notep->n_descsz) != true)
             return false;
       }
       p = descdata + ROUNDUP(notep->n_descsz, 4);
    }
    free(buf);
    return true;
 err:
    if (buf) free(buf);
    return false;
 }
 // read all segments from core file
 static bool read_core_segments(struct ps_prochandle* ph, ELF_EHDR* core_ehdr) {
    int i = 0;
    ELF_PHDR* phbuf = NULL;
    ELF_PHDR* core_php = NULL;
    if ((phbuf =  read_program_header_table(ph->core->core_fd, core_ehdr)) == NULL)
       return false;
    /*
     * Now iterate through the program headers in the core file.
     * We're interested in two types of Phdrs: PT_NOTE (which
     * contains a set of saved /proc structures), and PT_LOAD (which
     * represents a memory mapping from the process's address space).
     *
     * Difference b/w Solaris PT_NOTE and Linux PT_NOTE:
     *
     *     In Solaris there are two PT_NOTE segments the first PT_NOTE (if present)
     *     contains /proc structs in the pre-2.6 unstructured /proc format. the last
     *     PT_NOTE has data in new /proc format.
     *
     *     In Solaris, there is only one pstatus (process status). pstatus contains
     *     integer register set among other stuff. For each LWP, we have one lwpstatus
     *     entry that has integer regset for that LWP.
     *
     *     Linux threads are actually 'clone'd processes. To support core analysis
     *     of "multithreaded" process, Linux creates more than one pstatus (called
     *     "prstatus") entry in PT_NOTE. Each prstatus entry has integer regset for one
     *     "thread". Please refer to Linux kernel src file 'fs/binfmt_elf.c', in particular
     *     function "elf_core_dump".
     */
     for (core_php = phbuf, i = 0; i < core_ehdr->e_phnum; i++) {
       switch (core_php->p_type) {
          case PT_NOTE:
             if (core_handle_note(ph, core_php) != true) goto err;
             break;
          case PT_LOAD: {
             if (core_php->p_filesz != 0) {
                if (add_map_info(ph, ph->core->core_fd, core_php->p_offset,
                   core_php->p_vaddr, core_php->p_filesz) == NULL) goto err;
             }
             break;
          }
       }
       core_php++;
    }
    free(phbuf);
    return true;
 err:
    free(phbuf);
    return false;
 }
 // read segments of a shared object
 static bool read_lib_segments(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* lib_ehdr, uintptr_t lib_base) {
    int i = 0;
    ELF_PHDR* phbuf;
    ELF_PHDR* lib_php = NULL;
    if ((phbuf = read_program_header_table(lib_fd, lib_ehdr)) == NULL)
       return false;
    // we want to process only PT_LOAD segments that are not writable.
    // i.e., text segments. The read/write/exec (data) segments would
    // have been already added from core file segments.
    for (lib_php = phbuf, i = 0; i < lib_ehdr->e_phnum; i++) {
       if ((lib_php->p_type == PT_LOAD) && !(lib_php->p_flags & PF_W) && (lib_php->p_filesz != 0)) {
          if (add_map_info(ph, lib_fd, lib_php->p_offset, lib_php->p_vaddr + lib_base, lib_php->p_filesz) == NULL)
             goto err;
       }
       lib_php++;
    }
    free(phbuf);
    return true;
 err:
    free(phbuf);
    return false;
 }
 // process segments from interpreter (ld.so or ld-linux.so)
 static bool read_interp_segments(struct ps_prochandle* ph) {
    ELF_EHDR interp_ehdr;
    if (read_elf_header(ph->core->interp_fd, &interp_ehdr) != true) {
        print_debug("interpreter is not a valid ELF file\n");
        return false;
    }
    if (read_lib_segments(ph, ph->core->interp_fd, &interp_ehdr, ph->core->ld_base_addr) != true) {
        print_debug("can't read segments of interpreter\n");
        return false;
    }
    return true;
 }
 // process segments of a a.out
 static bool read_exec_segments(struct ps_prochandle* ph, ELF_EHDR* exec_ehdr) {
    int i = 0;
    ELF_PHDR* phbuf = NULL;
    ELF_PHDR* exec_php = NULL;
    if ((phbuf = read_program_header_table(ph->core->exec_fd, exec_ehdr)) == NULL)
       return false;
    for (exec_php = phbuf, i = 0; i < exec_ehdr->e_phnum; i++) {
       switch (exec_php->p_type) {
          // add mappings for PT_LOAD segments
          case PT_LOAD: {
             // add only non-writable segments of non-zero filesz
             if (!(exec_php->p_flags & PF_W) && exec_php->p_filesz != 0) {
                if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz) == NULL) goto err;
             }
             break;
          }
          // read the interpreter and it's segments
          case PT_INTERP: {
             char interp_name[BUF_SIZE];
             pread(ph->core->exec_fd, interp_name, MIN(exec_php->p_filesz, BUF_SIZE), exec_php->p_offset);
             print_debug("ELF interpreter %s\n", interp_name);
             // read interpreter segments as well
             if ((ph->core->interp_fd = pathmap_open(interp_name)) < 0) {
                print_debug("can't open runtime loader\n");
                goto err;
             }
             break;
          }
          // from PT_DYNAMIC we want to read address of first link_map addr
          case PT_DYNAMIC: {
             ph->core->dynamic_addr = exec_php->p_vaddr;
             print_debug("address of _DYNAMIC is 0x%lx\n", ph->core->dynamic_addr);
             break;
          }
       } // switch
       exec_php++;
    } // for
    free(phbuf);
    return true;
 err:
    free(phbuf);
    return false;
 }
 #define FIRST_LINK_MAP_OFFSET offsetof(struct r_debug,  r_map)
 #define LD_BASE_OFFSET        offsetof(struct r_debug,  r_ldbase)
 #define LINK_MAP_ADDR_OFFSET  offsetof(struct link_map, l_addr)
 #define LINK_MAP_NAME_OFFSET  offsetof(struct link_map, l_name)
 #define LINK_MAP_NEXT_OFFSET  offsetof(struct link_map, l_next)
 // read shared library info from runtime linker's data structures.
 // This work is done by librtlb_db in Solaris
 static bool read_shared_lib_info(struct ps_prochandle* ph) {
    uintptr_t addr = ph->core->dynamic_addr;
    uintptr_t debug_base;
    uintptr_t first_link_map_addr;
    uintptr_t ld_base_addr;
    uintptr_t link_map_addr;
    uintptr_t lib_base_diff;
    uintptr_t lib_base;
    uintptr_t lib_name_addr;
    char lib_name[BUF_SIZE];
    ELF_DYN dyn;
    ELF_EHDR elf_ehdr;
    int lib_fd;
    // _DYNAMIC has information of the form
    //         [tag] [data] [tag] [data] .....
    // Both tag and data are pointer sized.
    // We look for dynamic info with DT_DEBUG. This has shared object info.
    // refer to struct r_debug in link.h
    dyn.d_tag = DT_NULL;
    while (dyn.d_tag != DT_DEBUG) {
       if (ps_pdread(ph, (psaddr_t) addr, &dyn, sizeof(ELF_DYN)) != PS_OK) {
          print_debug("can't read debug info from _DYNAMIC\n");
          return false;
       }
       addr += sizeof(ELF_DYN);
    }
    // we have got Dyn entry with DT_DEBUG
    debug_base = dyn.d_un.d_ptr;
    // at debug_base we have struct r_debug. This has first link map in r_map field
    if (ps_pdread(ph, (psaddr_t) debug_base + FIRST_LINK_MAP_OFFSET,
                  &first_link_map_addr, sizeof(uintptr_t)) != PS_OK) {
       print_debug("can't read first link map address\n");
       return false;
    }
    // read ld_base address from struct r_debug
    if (ps_pdread(ph, (psaddr_t) debug_base + LD_BASE_OFFSET, &ld_base_addr,
                  sizeof(uintptr_t)) != PS_OK) {
       print_debug("can't read ld base address\n");
       return false;
    }
    ph->core->ld_base_addr = ld_base_addr;
    print_debug("interpreter base address is 0x%lx\n", ld_base_addr);
    // now read segments from interp (i.e ld.so or ld-linux.so)
    if (read_interp_segments(ph) != true)
       return false;
    // after adding interpreter (ld.so) mappings sort again
    if (sort_map_array(ph) != true)
       return false;
    print_debug("first link map is at 0x%lx\n", first_link_map_addr);
    link_map_addr = first_link_map_addr;
    while (link_map_addr != 0) {
       // read library base address of the .so. Note that even though <sys/link.h> calls
       // link_map->l_addr as "base address",  this is * not * really base virtual
       // address of the shared object. This is actually the difference b/w the virtual
       // address mentioned in shared object and the actual virtual base where runtime
       // linker loaded it. We use "base diff" in read_lib_segments call below.
       if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_ADDR_OFFSET,
                    &lib_base_diff, sizeof(uintptr_t)) != PS_OK) {
          print_debug("can't read shared object base address diff\n");
          return false;
       }
       // read address of the name
       if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NAME_OFFSET,
                     &lib_name_addr, sizeof(uintptr_t)) != PS_OK) {
          print_debug("can't read address of shared object name\n");
          return false;
       }
       // read name of the shared object
       lib_name[0] = '\0';
       if (lib_name_addr != 0 &&
           read_string(ph, (uintptr_t) lib_name_addr, lib_name, sizeof(lib_name)) != true) {
          print_debug("can't read shared object name\n");
          // don't let failure to read the name stop opening the file.  If something is really wrong
          // it will fail later.
       }
       if (lib_name[0] != '\0') {
          // ignore empty lib names
          lib_fd = pathmap_open(lib_name);
          if (lib_fd < 0) {
             print_debug("can't open shared object %s\n", lib_name);
             // continue with other libraries...
          } else {
             if (read_elf_header(lib_fd, &elf_ehdr)) {
                lib_base = lib_base_diff + find_base_address(lib_fd, &elf_ehdr);
                print_debug("reading library %s @ 0x%lx [ 0x%lx ]\n",
                            lib_name, lib_base, lib_base_diff);
                // while adding library mappings we need to use "base difference".
                if (! read_lib_segments(ph, lib_fd, &elf_ehdr, lib_base_diff)) {
                   print_debug("can't read shared object's segments\n");
                   close(lib_fd);
                   return false;
                }
                add_lib_info_fd(ph, lib_name, lib_fd, lib_base);
                // Map info is added for the library (lib_name) so
                // we need to re-sort it before calling the p_pdread.
                if (sort_map_array(ph) != true)
                   return false;
             } else {
                print_debug("can't read ELF header for shared object %s\n", lib_name);
                close(lib_fd);
                // continue with other libraries...
             }
          }
       }
       // read next link_map address
       if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NEXT_OFFSET,
                         &link_map_addr, sizeof(uintptr_t)) != PS_OK) {
          print_debug("can't read next link in link_map\n");
          return false;
       }
    }
    return true;
 }
 // the one and only one exposed stuff from this file
 struct ps_prochandle* Pgrab_core(const char* exec_file, const char* core_file) {
    ELF_EHDR core_ehdr;
    ELF_EHDR exec_ehdr;
    ELF_EHDR lib_ehdr;
    struct ps_prochandle* ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle));
    if (ph == NULL) {
       print_debug("can't allocate ps_prochandle\n");
       return NULL;
    }
    if ((ph->core = (struct core_data*) calloc(1, sizeof(struct core_data))) == NULL) {
       free(ph);
       print_debug("can't allocate ps_prochandle\n");
       return NULL;
    }
    // initialize ph
    ph->ops = &core_ops;
    ph->core->core_fd   = -1;
    ph->core->exec_fd   = -1;
    ph->core->interp_fd = -1;
    // open the core file
    if ((ph->core->core_fd = open(core_file, O_RDONLY)) < 0) {
       print_debug("can't open core file\n");
       goto err;
    }
    // read core file ELF header
    if (read_elf_header(ph->core->core_fd, &core_ehdr) != true || core_ehdr.e_type != ET_CORE) {
       print_debug("core file is not a valid ELF ET_CORE file\n");
       goto err;
    }
    if ((ph->core->exec_fd = open(exec_file, O_RDONLY)) < 0) {
       print_debug("can't open executable file\n");
       goto err;
    }
    if (read_elf_header(ph->core->exec_fd, &exec_ehdr) != true || exec_ehdr.e_type != ET_EXEC) {
       print_debug("executable file is not a valid ELF ET_EXEC file\n");
       goto err;
    }
    // process core file segments
    if (read_core_segments(ph, &core_ehdr) != true)
       goto err;
    // process exec file segments
    if (read_exec_segments(ph, &exec_ehdr) != true)
       goto err;
    // exec file is also treated like a shared object for symbol search
    if (add_lib_info_fd(ph, exec_file, ph->core->exec_fd,
                        (uintptr_t)0 + find_base_address(ph->core->exec_fd, &exec_ehdr)) == NULL)
       goto err;
    // allocate and sort maps into map_array, we need to do this
    // here because read_shared_lib_info needs to read from debuggee
    // address space
    if (sort_map_array(ph) != true)
       goto err;
    if (read_shared_lib_info(ph) != true)
       goto err;
    // sort again because we have added more mappings from shared objects
    if (sort_map_array(ph) != true)
       goto err;
    if (init_classsharing_workaround(ph) != true)
       goto err;
    return ph;
 err:
    Prelease(ph);
    return NULL;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

agent/src/os/linux/ps_core.c@da91efe96a93 (annotated)

agent/src/os/linux/ps_core.c