1 /*
   2  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright 2012, 2013 SAP AG. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 
  28 #if !defined(_WINDOWS) && !defined(__APPLE__)
  29 
  30 #include "memory/allocation.inline.hpp"
  31 #include "utilities/elfFuncDescTable.hpp"
  32 
  33 ElfFuncDescTable::ElfFuncDescTable(FILE* file, Elf_Shdr shdr, int index) {
  34   assert(file, "null file handle");
  35   // The actual function address (i.e. function entry point) is always the
  36   // first value in the function descriptor (on IA64 and PPC64 they look as follows):
  37   // PPC64: [function entry point, TOC pointer, environment pointer]
  38   // IA64 : [function entry point, GP (global pointer) value]
  39   // Unfortunately 'shdr.sh_entsize' doesn't always seem to contain this size (it's zero on PPC64) so we can't assert
  40   // assert(IA64_ONLY(2) PPC64_ONLY(3) * sizeof(address) == shdr.sh_entsize, "Size mismatch for '.opd' section entries");
  41 
  42   m_funcDescs = NULL;
  43   m_file = file;
  44   m_index = index;
  45   m_status = NullDecoder::no_error;
  46 
  47   // try to load the function descriptor table
  48   long cur_offset = ftell(file);
  49   if (cur_offset != -1) {
  50     // call malloc so we can back up if memory allocation fails.
  51     m_funcDescs = (address*)os::malloc(shdr.sh_size, mtInternal);
  52     if (m_funcDescs) {
  53       if (fseek(file, shdr.sh_offset, SEEK_SET) ||
  54           fread((void*)m_funcDescs, shdr.sh_size, 1, file) != 1 ||
  55           fseek(file, cur_offset, SEEK_SET)) {
  56         m_status = NullDecoder::file_invalid;
  57         os::free(m_funcDescs);
  58         m_funcDescs = NULL;
  59       }
  60     }
  61     if (!NullDecoder::is_error(m_status)) {
  62       memcpy(&m_shdr, &shdr, sizeof(Elf_Shdr));
  63     }
  64   } else {
  65     m_status = NullDecoder::file_invalid;
  66   }
  67 }
  68 
  69 ElfFuncDescTable::~ElfFuncDescTable() {
  70   if (m_funcDescs != NULL) {
  71     os::free(m_funcDescs);
  72   }
  73 }
  74 
  75 address ElfFuncDescTable::lookup(Elf_Word index) {
  76   if (NullDecoder::is_error(m_status)) {
  77     return NULL;
  78   }
  79 
  80   if (m_funcDescs != NULL) {
  81     if (m_shdr.sh_size > 0 && m_shdr.sh_addr <= index && index <= m_shdr.sh_addr + m_shdr.sh_size) {
  82       // Notice that 'index' is a byte-offset into the function descriptor table.
  83       return m_funcDescs[(index - m_shdr.sh_addr) / sizeof(address)];
  84     }
  85     return NULL;
  86   } else {
  87     long cur_pos;
  88     address addr;
  89     if (!(m_shdr.sh_size > 0 && m_shdr.sh_addr <= index && index <= m_shdr.sh_addr + m_shdr.sh_size)) {
  90       // don't put the whole decoder in error mode if we just tried a wrong index
  91       return NULL;
  92     }
  93     if ((cur_pos = ftell(m_file)) == -1 ||
  94         fseek(m_file, m_shdr.sh_offset + index - m_shdr.sh_addr, SEEK_SET) ||
  95         fread(&addr, sizeof(addr), 1, m_file) != 1 ||
  96         fseek(m_file, cur_pos, SEEK_SET)) {
  97       m_status = NullDecoder::file_invalid;
  98       return NULL;
  99     }
 100     return addr;
 101   }
 102 }
 103 
 104 #endif // !_WINDOWS && !__APPLE__