aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "precompiled.hpp"
aoqi@0: 
aoqi@0: #if !defined(_WINDOWS) && !defined(__APPLE__)
aoqi@0: 
aoqi@0: #include <string.h>
aoqi@0: #include <stdio.h>
aoqi@0: #include <limits.h>
aoqi@0: #include <new>
aoqi@0: 
aoqi@0: #include "memory/allocation.inline.hpp"
aoqi@0: #include "utilities/decoder.hpp"
aoqi@0: #include "utilities/elfFile.hpp"
aoqi@0: #include "utilities/elfFuncDescTable.hpp"
aoqi@0: #include "utilities/elfStringTable.hpp"
aoqi@0: #include "utilities/elfSymbolTable.hpp"
aoqi@0: 
aoqi@0: 
aoqi@0: ElfFile::ElfFile(const char* filepath) {
aoqi@0:   assert(filepath, "null file path");
aoqi@0:   memset(&m_elfHdr, 0, sizeof(m_elfHdr));
aoqi@0:   m_string_tables = NULL;
aoqi@0:   m_symbol_tables = NULL;
aoqi@0:   m_funcDesc_table = NULL;
aoqi@0:   m_next = NULL;
aoqi@0:   m_status = NullDecoder::no_error;
aoqi@0: 
aoqi@0:   int len = strlen(filepath) + 1;
aoqi@0:   m_filepath = (const char*)os::malloc(len * sizeof(char), mtInternal);
aoqi@0:   if (m_filepath != NULL) {
aoqi@0:     strcpy((char*)m_filepath, filepath);
aoqi@0:     m_file = fopen(filepath, "r");
aoqi@0:     if (m_file != NULL) {
aoqi@0:       load_tables();
aoqi@0:     } else {
aoqi@0:       m_status = NullDecoder::file_not_found;
aoqi@0:     }
aoqi@0:   } else {
aoqi@0:     m_status = NullDecoder::out_of_memory;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: ElfFile::~ElfFile() {
aoqi@0:   if (m_string_tables != NULL) {
aoqi@0:     delete m_string_tables;
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (m_symbol_tables != NULL) {
aoqi@0:     delete m_symbol_tables;
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (m_file != NULL) {
aoqi@0:     fclose(m_file);
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (m_filepath != NULL) {
aoqi@0:     os::free((void*)m_filepath);
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (m_next != NULL) {
aoqi@0:     delete m_next;
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: //Check elf header to ensure the file is valid.
aoqi@0: bool ElfFile::is_elf_file(Elf_Ehdr& hdr) {
aoqi@0:   return (ELFMAG0 == hdr.e_ident[EI_MAG0] &&
aoqi@0:       ELFMAG1 == hdr.e_ident[EI_MAG1] &&
aoqi@0:       ELFMAG2 == hdr.e_ident[EI_MAG2] &&
aoqi@0:       ELFMAG3 == hdr.e_ident[EI_MAG3] &&
aoqi@0:       ELFCLASSNONE != hdr.e_ident[EI_CLASS] &&
aoqi@0:       ELFDATANONE != hdr.e_ident[EI_DATA]);
aoqi@0: }
aoqi@0: 
aoqi@0: bool ElfFile::load_tables() {
aoqi@0:   assert(m_file, "file not open");
aoqi@0:   assert(!NullDecoder::is_error(m_status), "already in error");
aoqi@0: 
aoqi@0:   // read elf file header
aoqi@0:   if (fread(&m_elfHdr, sizeof(m_elfHdr), 1, m_file) != 1) {
aoqi@0:     m_status = NullDecoder::file_invalid;
aoqi@0:     return false;
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (!is_elf_file(m_elfHdr)) {
aoqi@0:     m_status = NullDecoder::file_invalid;
aoqi@0:     return false;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // walk elf file's section headers, and load string tables
aoqi@0:   Elf_Shdr shdr;
aoqi@0:   if (!fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {
aoqi@0:     if (NullDecoder::is_error(m_status)) return false;
aoqi@0: 
aoqi@0:     for (int index = 0; index < m_elfHdr.e_shnum; index ++) {
aoqi@0:       if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {
aoqi@0:         m_status = NullDecoder::file_invalid;
aoqi@0:         return false;
aoqi@0:       }
aoqi@0:       if (shdr.sh_type == SHT_STRTAB) {
aoqi@0:         // string tables
aoqi@0:         ElfStringTable* table = new (std::nothrow) ElfStringTable(m_file, shdr, index);
aoqi@0:         if (table == NULL) {
aoqi@0:           m_status = NullDecoder::out_of_memory;
aoqi@0:           return false;
aoqi@0:         }
aoqi@0:         add_string_table(table);
aoqi@0:       } else if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {
aoqi@0:         // symbol tables
aoqi@0:         ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(m_file, shdr);
aoqi@0:         if (table == NULL) {
aoqi@0:           m_status = NullDecoder::out_of_memory;
aoqi@0:           return false;
aoqi@0:         }
aoqi@0:         add_symbol_table(table);
aoqi@0:       }
aoqi@0:     }
aoqi@0: 
aoqi@0: #if defined(PPC64) && !defined(ABI_ELFv2)
aoqi@0:     // Now read the .opd section wich contains the PPC64 function descriptor table.
aoqi@0:     // The .opd section is only available on PPC64 (see for example:
aoqi@0:     // http://refspecs.linuxfoundation.org/LSB_3.1.1/LSB-Core-PPC64/LSB-Core-PPC64/specialsections.html)
aoqi@0:     // so this code should do no harm on other platforms but because of performance reasons we only
aoqi@0:     // execute it on PPC64 platforms.
aoqi@0:     // Notice that we can only find the .opd section after we have successfully read in the string
aoqi@0:     // tables in the previous loop, because we need to query the name of each section which is
aoqi@0:     // contained in one of the string tables (i.e. the one with the index m_elfHdr.e_shstrndx).
aoqi@0: 
aoqi@0:     // Reset the file pointer
aoqi@0:     if (fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {
aoqi@0:       m_status = NullDecoder::file_invalid;
aoqi@0:       return false;
aoqi@0:     }
aoqi@0:     for (int index = 0; index < m_elfHdr.e_shnum; index ++) {
aoqi@0:       if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {
aoqi@0:         m_status = NullDecoder::file_invalid;
aoqi@0:         return false;
aoqi@0:       }
aoqi@0:       if (m_elfHdr.e_shstrndx != SHN_UNDEF && shdr.sh_type == SHT_PROGBITS) {
aoqi@0:         ElfStringTable* string_table = get_string_table(m_elfHdr.e_shstrndx);
aoqi@0:         if (string_table == NULL) {
aoqi@0:           m_status = NullDecoder::file_invalid;
aoqi@0:           return false;
aoqi@0:         }
aoqi@0:         char buf[8]; // '8' is enough because we only want to read ".opd"
aoqi@0:         if (string_table->string_at(shdr.sh_name, buf, sizeof(buf)) && !strncmp(".opd", buf, 4)) {
aoqi@0:           m_funcDesc_table = new (std::nothrow) ElfFuncDescTable(m_file, shdr, index);
aoqi@0:           if (m_funcDesc_table == NULL) {
aoqi@0:             m_status = NullDecoder::out_of_memory;
aoqi@0:             return false;
aoqi@0:           }
aoqi@0:           break;
aoqi@0:         }
aoqi@0:       }
aoqi@0:     }
aoqi@0: #endif
aoqi@0: 
aoqi@0:   }
aoqi@0:   return true;
aoqi@0: }
aoqi@0: 
aoqi@0: bool ElfFile::decode(address addr, char* buf, int buflen, int* offset) {
aoqi@0:   // something already went wrong, just give up
aoqi@0:   if (NullDecoder::is_error(m_status)) {
aoqi@0:     return false;
aoqi@0:   }
aoqi@0:   ElfSymbolTable* symbol_table = m_symbol_tables;
aoqi@0:   int string_table_index;
aoqi@0:   int pos_in_string_table;
aoqi@0:   int off = INT_MAX;
aoqi@0:   bool found_symbol = false;
aoqi@0:   while (symbol_table != NULL) {
aoqi@0:     if (symbol_table->lookup(addr, &string_table_index, &pos_in_string_table, &off, m_funcDesc_table)) {
aoqi@0:       found_symbol = true;
aoqi@0:       break;
aoqi@0:     }
aoqi@0:     symbol_table = symbol_table->m_next;
aoqi@0:   }
aoqi@0:   if (!found_symbol) return false;
aoqi@0: 
aoqi@0:   ElfStringTable* string_table = get_string_table(string_table_index);
aoqi@0: 
aoqi@0:   if (string_table == NULL) {
aoqi@0:     m_status = NullDecoder::file_invalid;
aoqi@0:     return false;
aoqi@0:   }
aoqi@0:   if (offset) *offset = off;
aoqi@0: 
aoqi@0:   return string_table->string_at(pos_in_string_table, buf, buflen);
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: void ElfFile::add_symbol_table(ElfSymbolTable* table) {
aoqi@0:   if (m_symbol_tables == NULL) {
aoqi@0:     m_symbol_tables = table;
aoqi@0:   } else {
aoqi@0:     table->m_next = m_symbol_tables;
aoqi@0:     m_symbol_tables = table;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void ElfFile::add_string_table(ElfStringTable* table) {
aoqi@0:   if (m_string_tables == NULL) {
aoqi@0:     m_string_tables = table;
aoqi@0:   } else {
aoqi@0:     table->m_next = m_string_tables;
aoqi@0:     m_string_tables = table;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: ElfStringTable* ElfFile::get_string_table(int index) {
aoqi@0:   ElfStringTable* p = m_string_tables;
aoqi@0:   while (p != NULL) {
aoqi@0:     if (p->index() == index) return p;
aoqi@0:     p = p->m_next;
aoqi@0:   }
aoqi@0:   return NULL;
aoqi@0: }
aoqi@0: 
aoqi@0: #ifdef LINUX
aoqi@0: bool ElfFile::specifies_noexecstack() {
aoqi@0:   Elf_Phdr phdr;
aoqi@0:   if (!m_file)  return true;
aoqi@0: 
aoqi@0:   if (!fseek(m_file, m_elfHdr.e_phoff, SEEK_SET)) {
aoqi@0:     for (int index = 0; index < m_elfHdr.e_phnum; index ++) {
aoqi@0:       if (fread((void*)&phdr, sizeof(Elf_Phdr), 1, m_file) != 1) {
aoqi@0:         m_status = NullDecoder::file_invalid;
aoqi@0:         return false;
aoqi@0:       }
aoqi@0:       if (phdr.p_type == PT_GNU_STACK) {
aoqi@0:         if (phdr.p_flags == (PF_R | PF_W))  {
aoqi@0:           return true;
aoqi@0:         } else {
aoqi@0:           return false;
aoqi@0:         }
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
cjplummer@7857: // AARCH64 defaults to noexecstack. All others default to execstack.
cjplummer@7857: #ifdef AARCH64
cjplummer@7857:   return true;
cjplummer@7857: #else
aoqi@0:   return false;
cjplummer@7857: #endif
aoqi@0: }
aoqi@0: #endif
aoqi@0: 
aoqi@0: #endif // !_WINDOWS && !__APPLE__