1 /* 2 * Copyright (c) 1997, 2018, 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 "jvm.h" 26 #include "utilities/decoder_elf.hpp" 27 #include "utilities/elfFile.hpp" 28 29 #include <cxxabi.h> 30 31 bool ElfDecoder::demangle(const char* symbol, char *buf, int buflen) { 32 int status; 33 char* result; 34 size_t size = (size_t)buflen; 35 36 #ifdef PPC64 37 // On PPC64 ElfDecoder::decode() may return a dot (.) prefixed name 38 // (see elfFuncDescTable.hpp for details) 39 if (symbol && *symbol == '.') symbol += 1; 40 #endif 41 42 // Don't pass buf to __cxa_demangle. In case of the 'buf' is too small, 43 // __cxa_demangle will call system "realloc" for additional memory, which 44 // may use different malloc/realloc mechanism that allocates 'buf'. 45 if ((result = abi::__cxa_demangle(symbol, NULL, NULL, &status)) != NULL) { 46 jio_snprintf(buf, buflen, "%s", result); 47 // call c library's free 48 ::free(result); 49 return true; 50 } 51 return false; 52 } 53 54 // Returns true if the elf file is marked NOT to require an executable stack, 55 // or if the file could not be opened. 56 // Returns false if the elf file requires an executable stack, the stack flag 57 // is not set at all, or if the file can not be read. 58 bool ElfFile::specifies_noexecstack(const char* filepath) { 59 if (filepath == NULL) return true; 60 61 FILE* file = fopen(filepath, "r"); 62 if (file == NULL) return true; 63 64 // AARCH64 defaults to noexecstack. All others default to execstack. 65 bool result = AARCH64_ONLY(true) NOT_AARCH64(false); 66 67 // Read file header 68 Elf_Ehdr head; 69 if (fread(&head, sizeof(Elf_Ehdr), 1, file) == 1 && 70 is_elf_file(head) && 71 fseek(file, head.e_phoff, SEEK_SET) == 0) { 72 73 // Read program header table 74 Elf_Phdr phdr; 75 for (int index = 0; index < head.e_phnum; index ++) { 76 if (fread((void*)&phdr, sizeof(Elf_Phdr), 1, file) != 1) { 77 result = false; 78 break; 79 } 80 if (phdr.p_type == PT_GNU_STACK) { 81 result = (phdr.p_flags == (PF_R | PF_W)); 82 break; 83 } 84 } 85 } 86 fclose(file); 87 return result; 88 }