Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 1997, 2013, 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 "precompiled.hpp"

 #if !defined(_WINDOWS) && !defined(__APPLE__)

 #include <string.h>

 #include <stdio.h>

 #include <limits.h>

 #include <new>

 #include "memory/allocation.inline.hpp"

 #include "utilities/decoder.hpp"

 #include "utilities/elfFile.hpp"

 #include "utilities/elfFuncDescTable.hpp"

 #include "utilities/elfStringTable.hpp"

 #include "utilities/elfSymbolTable.hpp"

 ElfFile::ElfFile(const char* filepath) {

   assert(filepath, "null file path");

   memset(&m_elfHdr, 0, sizeof(m_elfHdr));

   m_string_tables = NULL;

   m_symbol_tables = NULL;

   m_funcDesc_table = NULL;

   m_next = NULL;

   m_status = NullDecoder::no_error;

   int len = strlen(filepath) + 1;

   m_filepath = (const char*)os::malloc(len * sizeof(char), mtInternal);

   if (m_filepath != NULL) {

     strcpy((char*)m_filepath, filepath);

     m_file = fopen(filepath, "r");

     if (m_file != NULL) {

       load_tables();

     } else {

       m_status = NullDecoder::file_not_found;

     }

   } else {

     m_status = NullDecoder::out_of_memory;

   }

 }

 ElfFile::~ElfFile() {

   if (m_string_tables != NULL) {

     delete m_string_tables;

   }

   if (m_symbol_tables != NULL) {

     delete m_symbol_tables;

   }

   if (m_file != NULL) {

     fclose(m_file);

   }

   if (m_filepath != NULL) {

     os::free((void*)m_filepath);

   }

   if (m_next != NULL) {

     delete m_next;

   }

 };

 //Check elf header to ensure the file is valid.

 bool ElfFile::is_elf_file(Elf_Ehdr& hdr) {

   return (ELFMAG0 == hdr.e_ident[EI_MAG0] &&

       ELFMAG1 == hdr.e_ident[EI_MAG1] &&

       ELFMAG2 == hdr.e_ident[EI_MAG2] &&

       ELFMAG3 == hdr.e_ident[EI_MAG3] &&

       ELFCLASSNONE != hdr.e_ident[EI_CLASS] &&

       ELFDATANONE != hdr.e_ident[EI_DATA]);

 }

 bool ElfFile::load_tables() {

   assert(m_file, "file not open");

   assert(!NullDecoder::is_error(m_status), "already in error");

   // read elf file header

   if (fread(&m_elfHdr, sizeof(m_elfHdr), 1, m_file) != 1) {

     m_status = NullDecoder::file_invalid;

     return false;

   }

   if (!is_elf_file(m_elfHdr)) {

     m_status = NullDecoder::file_invalid;

     return false;

   }

   // walk elf file's section headers, and load string tables

   Elf_Shdr shdr;

   if (!fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {

     if (NullDecoder::is_error(m_status)) return false;

     for (int index = 0; index < m_elfHdr.e_shnum; index ++) {

       if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {

         m_status = NullDecoder::file_invalid;

         return false;

       }

       if (shdr.sh_type == SHT_STRTAB) {

         // string tables

         ElfStringTable* table = new (std::nothrow) ElfStringTable(m_file, shdr, index);

         if (table == NULL) {

           m_status = NullDecoder::out_of_memory;

           return false;

         }

         add_string_table(table);

       } else if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {

         // symbol tables

         ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(m_file, shdr);

         if (table == NULL) {

           m_status = NullDecoder::out_of_memory;

           return false;

         }

         add_symbol_table(table);

       }

     }

 #if defined(PPC64)

     // Now read the .opd section wich contains the PPC64 function descriptor table.

     // The .opd section is only available on PPC64 (see for example:

     // http://refspecs.linuxfoundation.org/LSB_3.1.1/LSB-Core-PPC64/LSB-Core-PPC64/specialsections.html)

     // so this code should do no harm on other platforms but because of performance reasons we only

     // execute it on PPC64 platforms.

     // Notice that we can only find the .opd section after we have successfully read in the string

     // tables in the previous loop, because we need to query the name of each section which is

     // contained in one of the string tables (i.e. the one with the index m_elfHdr.e_shstrndx).

     // Reset the file pointer

     if (fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {

       m_status = NullDecoder::file_invalid;

       return false;

     }

     for (int index = 0; index < m_elfHdr.e_shnum; index ++) {

       if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {

         m_status = NullDecoder::file_invalid;

         return false;

       }

       if (m_elfHdr.e_shstrndx != SHN_UNDEF && shdr.sh_type == SHT_PROGBITS) {

         ElfStringTable* string_table = get_string_table(m_elfHdr.e_shstrndx);

         if (string_table == NULL) {

           m_status = NullDecoder::file_invalid;

           return false;

         }

         char buf[8]; // '8' is enough because we only want to read ".opd"

         if (string_table->string_at(shdr.sh_name, buf, sizeof(buf)) && !strncmp(".opd", buf, 4)) {

           m_funcDesc_table = new (std::nothrow) ElfFuncDescTable(m_file, shdr, index);

           if (m_funcDesc_table == NULL) {

             m_status = NullDecoder::out_of_memory;

             return false;

           }

           break;

         }

       }

     }

 #endif

   }

   return true;

 }

 bool ElfFile::decode(address addr, char* buf, int buflen, int* offset) {

   // something already went wrong, just give up

   if (NullDecoder::is_error(m_status)) {

     return false;

   }

   ElfSymbolTable* symbol_table = m_symbol_tables;

   int string_table_index;

   int pos_in_string_table;

   int off = INT_MAX;

   bool found_symbol = false;

   while (symbol_table != NULL) {

     if (symbol_table->lookup(addr, &string_table_index, &pos_in_string_table, &off, m_funcDesc_table)) {

       found_symbol = true;

       break;

     }

     symbol_table = symbol_table->m_next;

   }

   if (!found_symbol) return false;

   ElfStringTable* string_table = get_string_table(string_table_index);

   if (string_table == NULL) {

     m_status = NullDecoder::file_invalid;

     return false;

   }

   if (offset) *offset = off;

   return string_table->string_at(pos_in_string_table, buf, buflen);

 }

 void ElfFile::add_symbol_table(ElfSymbolTable* table) {

   if (m_symbol_tables == NULL) {

     m_symbol_tables = table;

   } else {

     table->m_next = m_symbol_tables;

     m_symbol_tables = table;

   }

 }

 void ElfFile::add_string_table(ElfStringTable* table) {

   if (m_string_tables == NULL) {

     m_string_tables = table;

   } else {

     table->m_next = m_string_tables;

     m_string_tables = table;

   }

 }

 ElfStringTable* ElfFile::get_string_table(int index) {

   ElfStringTable* p = m_string_tables;

   while (p != NULL) {

     if (p->index() == index) return p;

     p = p->m_next;

   }

   return NULL;

 }

 #ifdef LINUX

 bool ElfFile::specifies_noexecstack() {

   Elf_Phdr phdr;

   if (!m_file)  return true;

   if (!fseek(m_file, m_elfHdr.e_phoff, SEEK_SET)) {

     for (int index = 0; index < m_elfHdr.e_phnum; index ++) {

       if (fread((void*)&phdr, sizeof(Elf_Phdr), 1, m_file) != 1) {

         m_status = NullDecoder::file_invalid;

         return false;

       }

       if (phdr.p_type == PT_GNU_STACK) {

         if (phdr.p_flags == (PF_R | PF_W))  {

           return true;

         } else {

           return false;

         }

       }

     }

   }

   return false;

 }

 #endif

 #endif // !_WINDOWS && !__APPLE__