1 /*
2 * Copyright (c) 2011, 2017, 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 "precompiled.hpp"
26
27 #ifdef __APPLE__
28 #include "jvm.h"
29 #include "decoder_machO.hpp"
30 #include "memory/allocation.inline.hpp"
31
32 #include <cxxabi.h>
33 #include <mach-o/loader.h>
34 #include <mach-o/nlist.h>
35
36
demangle(const char * symbol,char * buf,int buflen)37 bool MachODecoder::demangle(const char* symbol, char *buf, int buflen) {
38 int status;
39 char* result;
40 size_t size = (size_t)buflen;
41 // Don't pass buf to __cxa_demangle. In case of the 'buf' is too small,
42 // __cxa_demangle will call system "realloc" for additional memory, which
43 // may use different malloc/realloc mechanism that allocates 'buf'.
44 if ((result = abi::__cxa_demangle(symbol, NULL, NULL, &status)) != NULL) {
45 jio_snprintf(buf, buflen, "%s", result);
46 // call c library's free
47 ::free(result);
48 return true;
49 }
50 return false;
51 }
52
decode(address addr,char * buf,int buflen,int * offset,const void * mach_base)53 bool MachODecoder::decode(address addr, char *buf,
54 int buflen, int *offset, const void *mach_base) {
55 struct symtab_command * symt = (struct symtab_command *)
56 mach_find_command((struct mach_header_64 *)mach_base, LC_SYMTAB);
57 if (symt == NULL) {
58 DEBUG_ONLY(tty->print_cr("no symtab in mach file at 0x%lx", p2i(mach_base)));
59 return false;
60 }
61 uint32_t off = symt->symoff; /* symbol table offset (within this mach file) */
62 uint32_t nsyms = symt->nsyms; /* number of symbol table entries */
63 uint32_t stroff = symt->stroff; /* string table offset */
64 uint32_t strsize = symt->strsize; /* string table size in bytes */
65
66 // iterate through symbol table trying to match our offset
67
68 uint32_t addr_relative = (uintptr_t) mach_base - (uintptr_t) addr; // offset we seek in the symtab
69 void * symtab_addr = (void*) ((uintptr_t) mach_base + off);
70 struct nlist_64 *cur_nlist = (struct nlist_64 *) symtab_addr;
71 struct nlist_64 *last_nlist = cur_nlist; // no size stored in an entry, so keep previously seen nlist
72
73 int32_t found_strx = 0;
74 int32_t found_symval = 0;
75
76 for (uint32_t i=0; i < nsyms; i++) {
77 uint32_t this_value = cur_nlist->n_value;
78
79 if (addr_relative == this_value) {
80 found_strx = cur_nlist->n_un.n_strx;
81 found_symval = this_value;
82 break;
83 } else if (addr_relative > this_value) {
84 // gone past it, use previously seen nlist:
85 found_strx = last_nlist->n_un.n_strx;
86 found_symval = last_nlist->n_value;
87 break;
88 }
89 last_nlist = cur_nlist;
90 cur_nlist = cur_nlist + sizeof(struct nlist_64);
91 }
92 if (found_strx == 0) {
93 return false;
94 }
95 // write the offset:
96 *offset = addr_relative - found_symval;
97
98 // lookup found_strx in the string table
99 char * symname = mach_find_in_stringtable((char*) ((uintptr_t)mach_base + stroff), strsize, found_strx);
100 if (symname) {
101 strncpy(buf, symname, buflen);
102 buf[buflen - 1] = '\0';
103 return true;
104 }
105 DEBUG_ONLY(tty->print_cr("no string or null string found."));
106 return false;
107 }
108
mach_find_command(struct mach_header_64 * mach_base,uint32_t command_wanted)109 void* MachODecoder::mach_find_command(struct mach_header_64 * mach_base, uint32_t command_wanted) {
110 // possibly verify it is a mach_header, use magic number.
111 // commands begin immediately after the header.
112 struct load_command *pos = (struct load_command *) mach_base + sizeof(struct mach_header_64);
113 for (uint32_t i = 0; i < mach_base->ncmds; i++) {
114 struct load_command *this_cmd = (struct load_command *) pos;
115 if (this_cmd->cmd == command_wanted) {
116 return pos;
117 }
118 int cmdsize = this_cmd->cmdsize;
119 pos += cmdsize;
120 }
121 return NULL;
122 }
123
mach_find_in_stringtable(char * strtab,uint32_t tablesize,int strx_wanted)124 char* MachODecoder::mach_find_in_stringtable(char *strtab, uint32_t tablesize, int strx_wanted) {
125
126 if (strx_wanted == 0) {
127 return NULL;
128 }
129 char *strtab_end = strtab + tablesize;
130
131 // find the first string, skip over the space char
132 // (or the four zero bytes we see e.g. in libclient)
133 if (*strtab == ' ') {
134 strtab++;
135 if (*strtab != 0) {
136 DEBUG_ONLY(tty->print_cr("string table has leading space but no following zero."));
137 return NULL;
138 }
139 strtab++;
140 } else {
141 if ((uint32_t) *strtab != 0) {
142 DEBUG_ONLY(tty->print_cr("string table without leading space or leading int of zero."));
143 return NULL;
144 }
145 strtab+=4;
146 }
147 // read the real strings starting at index 1
148 int cur_strx = 1;
149 while (strtab < strtab_end) {
150 if (cur_strx == strx_wanted) {
151 return strtab;
152 }
153 // find start of next string
154 while (*strtab != 0) {
155 strtab++;
156 }
157 strtab++; // skip the terminating zero
158 cur_strx++;
159 }
160 DEBUG_ONLY(tty->print_cr("string number %d not found.", strx_wanted));
161 return NULL;
162 }
163
164
165 #endif
166
167
168