| /* |
| * Copyright (c) 2003, 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 <unistd.h> |
| #include <sys/procfs.h> |
| #include <search.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include "symtab.h" |
| #include "salibelf.h" |
| |
| |
| // ---------------------------------------------------- |
| // functions for symbol lookups |
| // ---------------------------------------------------- |
| |
| struct elf_section { |
| ELF_SHDR *c_shdr; |
| void *c_data; |
| }; |
| |
| struct elf_symbol { |
| char *name; |
| uintptr_t offset; |
| uintptr_t size; |
| }; |
| |
| typedef struct symtab { |
| char *strs; |
| size_t num_symbols; |
| struct elf_symbol *symbols; |
| struct hsearch_data *hash_table; |
| } symtab_t; |
| |
| |
| // Directory that contains global debuginfo files. In theory it |
| // should be possible to change this, but in a Java environment there |
| // is no obvious place to put a user interface to do it. Maybe this |
| // could be set with an environment variable. |
| static const char debug_file_directory[] = "/usr/lib/debug"; |
| |
| /* The CRC used in gnu_debuglink, retrieved from |
| http://sourceware.org/gdb/current/onlinedocs/gdb/Separate-Debug-Files.html#Separate-Debug-Files. */ |
| unsigned int gnu_debuglink_crc32 (unsigned int crc, |
| unsigned char *buf, size_t len) |
| { |
| static const unsigned int crc32_table[256] = |
| { |
| 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, |
| 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, |
| 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, |
| 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, |
| 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, |
| 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, |
| 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, |
| 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, |
| 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, |
| 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, |
| 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, |
| 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, |
| 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, |
| 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, |
| 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, |
| 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, |
| 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, |
| 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, |
| 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, |
| 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, |
| 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, |
| 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, |
| 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, |
| 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, |
| 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, |
| 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, |
| 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, |
| 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, |
| 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, |
| 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, |
| 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, |
| 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, |
| 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, |
| 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, |
| 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, |
| 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, |
| 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, |
| 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, |
| 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, |
| 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, |
| 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, |
| 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, |
| 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, |
| 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, |
| 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, |
| 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, |
| 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, |
| 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, |
| 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, |
| 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, |
| 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, |
| 0x2d02ef8d |
| }; |
| unsigned char *end; |
| |
| crc = ~crc & 0xffffffff; |
| for (end = buf + len; buf < end; ++buf) |
| crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8); |
| return ~crc & 0xffffffff; |
| } |
| |
| /* Open a debuginfo file and check its CRC. If it exists and the CRC |
| matches return its fd. */ |
| static int |
| open_debug_file (const char *pathname, unsigned int crc) |
| { |
| unsigned int file_crc = 0; |
| unsigned char buffer[8 * 1024]; |
| |
| int fd = pathmap_open(pathname); |
| |
| if (fd < 0) |
| return -1; |
| |
| lseek(fd, 0, SEEK_SET); |
| |
| for (;;) { |
| int len = read(fd, buffer, sizeof buffer); |
| if (len <= 0) |
| break; |
| file_crc = gnu_debuglink_crc32(file_crc, buffer, len); |
| } |
| |
| if (crc == file_crc) |
| return fd; |
| else { |
| close(fd); |
| return -1; |
| } |
| } |
| |
| /* Find an ELF section. */ |
| static struct elf_section *find_section_by_name(char *name, |
| int fd, |
| ELF_EHDR *ehdr, |
| ELF_SHDR *shbuf, |
| struct elf_section *scn_cache) |
| { |
| ELF_SHDR* cursct = NULL; |
| char *strtab; |
| int cnt; |
| |
| if (scn_cache[ehdr->e_shstrndx].c_data == NULL) { |
| if ((scn_cache[ehdr->e_shstrndx].c_data |
| = read_section_data(fd, ehdr, cursct)) == NULL) { |
| return NULL; |
| } |
| } |
| |
| strtab = scn_cache[ehdr->e_shstrndx].c_data; |
| |
| for (cursct = shbuf, cnt = 0; |
| cnt < ehdr->e_shnum; |
| cnt++, cursct++) { |
| if (strcmp(cursct->sh_name + strtab, name) == 0) { |
| scn_cache[cnt].c_data = read_section_data(fd, ehdr, cursct); |
| return &scn_cache[cnt]; |
| } |
| } |
| |
| return NULL; |
| } |
| |
| /* Look for a ".gnu_debuglink" section. If one exists, try to open a |
| suitable debuginfo file. */ |
| static int open_file_from_debug_link(const char *name, |
| int fd, |
| ELF_EHDR *ehdr, |
| ELF_SHDR *shbuf, |
| struct elf_section *scn_cache) |
| { |
| int debug_fd; |
| struct elf_section *debug_link = find_section_by_name(".gnu_debuglink", fd, ehdr, |
| shbuf, scn_cache); |
| if (debug_link == NULL) |
| return -1; |
| char *debug_filename = debug_link->c_data; |
| int offset = (strlen(debug_filename) + 4) >> 2; |
| static unsigned int crc; |
| crc = ((unsigned int*)debug_link->c_data)[offset]; |
| char *debug_pathname = malloc(strlen(debug_filename) |
| + strlen(name) |
| + strlen(".debug/") |
| + strlen(debug_file_directory) |
| + 2); |
| strcpy(debug_pathname, name); |
| char *last_slash = strrchr(debug_pathname, '/'); |
| if (last_slash == NULL) |
| return -1; |
| |
| /* Look in the same directory as the object. */ |
| strcpy(last_slash+1, debug_filename); |
| |
| debug_fd = open_debug_file(debug_pathname, crc); |
| if (debug_fd >= 0) { |
| free(debug_pathname); |
| return debug_fd; |
| } |
| |
| /* Look in a subdirectory named ".debug". */ |
| strcpy(last_slash+1, ".debug/"); |
| strcat(last_slash, debug_filename); |
| |
| debug_fd = open_debug_file(debug_pathname, crc); |
| if (debug_fd >= 0) { |
| free(debug_pathname); |
| return debug_fd; |
| } |
| |
| /* Look in /usr/lib/debug + the full pathname. */ |
| strcpy(debug_pathname, debug_file_directory); |
| strcat(debug_pathname, name); |
| last_slash = strrchr(debug_pathname, '/'); |
| strcpy(last_slash+1, debug_filename); |
| |
| debug_fd = open_debug_file(debug_pathname, crc); |
| if (debug_fd >= 0) { |
| free(debug_pathname); |
| return debug_fd; |
| } |
| |
| free(debug_pathname); |
| return -1; |
| } |
| |
| static struct symtab* build_symtab_internal(int fd, const char *filename, bool try_debuginfo); |
| |
| /* Look for a ".gnu_debuglink" section. If one exists, try to open a |
| suitable debuginfo file and read a symbol table from it. */ |
| static struct symtab *build_symtab_from_debug_link(const char *name, |
| int fd, |
| ELF_EHDR *ehdr, |
| ELF_SHDR *shbuf, |
| struct elf_section *scn_cache) |
| { |
| fd = open_file_from_debug_link(name, fd, ehdr, shbuf, scn_cache); |
| |
| if (fd >= 0) { |
| struct symtab *symtab = build_symtab_internal(fd, NULL, /* try_debuginfo */ false); |
| close(fd); |
| return symtab; |
| } |
| |
| return NULL; |
| } |
| |
| // Given a build_id, find the associated debuginfo file |
| static char * |
| build_id_to_debug_filename (size_t size, unsigned char *data) |
| { |
| char *filename, *s; |
| |
| filename = malloc(strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1 |
| + 2 * size + (sizeof ".debug" - 1) + 1); |
| s = filename + sprintf (filename, "%s/.build-id/", debug_file_directory); |
| if (size > 0) |
| { |
| size--; |
| s += sprintf (s, "%02x", *data++); |
| } |
| if (size > 0) |
| *s++ = '/'; |
| while (size-- > 0) |
| s += sprintf (s, "%02x", *data++); |
| strcpy (s, ".debug"); |
| |
| return filename; |
| } |
| |
| // Read a build ID note. Try to open any associated debuginfo file |
| // and return its symtab |
| static struct symtab* build_symtab_from_build_id(Elf64_Nhdr *note) |
| { |
| int fd; |
| struct symtab *symtab = NULL; |
| |
| unsigned char *bytes |
| = (unsigned char*)(note+1) + note->n_namesz; |
| char *filename |
| = (build_id_to_debug_filename (note->n_descsz, bytes)); |
| |
| fd = pathmap_open(filename); |
| if (fd >= 0) { |
| symtab = build_symtab_internal(fd, NULL, /* try_debuginfo */ false); |
| close(fd); |
| } |
| free(filename); |
| |
| return symtab; |
| } |
| |
| // read symbol table from given fd. If try_debuginfo) is true, also |
| // try to open an associated debuginfo file |
| static struct symtab* build_symtab_internal(int fd, const char *filename, bool try_debuginfo) { |
| ELF_EHDR ehdr; |
| char *names = NULL; |
| struct symtab* symtab = NULL; |
| |
| // Reading of elf header |
| struct elf_section *scn_cache = NULL; |
| int cnt = 0; |
| ELF_SHDR* shbuf = NULL; |
| ELF_SHDR* cursct = NULL; |
| ELF_PHDR* phbuf = NULL; |
| ELF_PHDR* phdr = NULL; |
| int sym_section = SHT_DYNSYM; |
| |
| uintptr_t baseaddr = (uintptr_t)-1; |
| |
| lseek(fd, (off_t)0L, SEEK_SET); |
| if (! read_elf_header(fd, &ehdr)) { |
| // not an elf |
| return NULL; |
| } |
| |
| // read ELF header |
| if ((shbuf = read_section_header_table(fd, &ehdr)) == NULL) { |
| goto quit; |
| } |
| |
| baseaddr = find_base_address(fd, &ehdr); |
| |
| scn_cache = (struct elf_section *) |
| calloc(ehdr.e_shnum * sizeof(struct elf_section), 1); |
| if (scn_cache == NULL) { |
| goto quit; |
| } |
| |
| for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) { |
| scn_cache[cnt].c_shdr = cursct; |
| if (cursct->sh_type == SHT_SYMTAB || cursct->sh_type == SHT_STRTAB |
| || cursct->sh_type == SHT_NOTE || cursct->sh_type == SHT_DYNSYM) { |
| if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) { |
| goto quit; |
| } |
| } |
| if (cursct->sh_type == SHT_SYMTAB) { |
| // Full symbol table available so use that |
| sym_section = cursct->sh_type; |
| } |
| cursct++; |
| } |
| |
| for (cnt = 1; cnt < ehdr.e_shnum; cnt++) { |
| ELF_SHDR *shdr = scn_cache[cnt].c_shdr; |
| |
| if (shdr->sh_type == sym_section) { |
| ELF_SYM *syms; |
| int j, n, rslt; |
| size_t size; |
| |
| // FIXME: there could be multiple data buffers associated with the |
| // same ELF section. Here we can handle only one buffer. See man page |
| // for elf_getdata on Solaris. |
| |
| // guarantee(symtab == NULL, "multiple symtab"); |
| symtab = (struct symtab*)calloc(1, sizeof(struct symtab)); |
| if (symtab == NULL) { |
| goto quit; |
| } |
| // the symbol table |
| syms = (ELF_SYM *)scn_cache[cnt].c_data; |
| |
| // number of symbols |
| n = shdr->sh_size / shdr->sh_entsize; |
| |
| // create hash table, we use hcreate_r, hsearch_r and hdestroy_r to |
| // manipulate the hash table. |
| symtab->hash_table = (struct hsearch_data*) calloc(1, sizeof(struct hsearch_data)); |
| rslt = hcreate_r(n, symtab->hash_table); |
| // guarantee(rslt, "unexpected failure: hcreate_r"); |
| |
| // shdr->sh_link points to the section that contains the actual strings |
| // for symbol names. the st_name field in ELF_SYM is just the |
| // string table index. we make a copy of the string table so the |
| // strings will not be destroyed by elf_end. |
| size = scn_cache[shdr->sh_link].c_shdr->sh_size; |
| symtab->strs = (char *)malloc(size); |
| memcpy(symtab->strs, scn_cache[shdr->sh_link].c_data, size); |
| |
| // allocate memory for storing symbol offset and size; |
| symtab->num_symbols = n; |
| symtab->symbols = (struct elf_symbol *)calloc(n , sizeof(struct elf_symbol)); |
| |
| // copy symbols info our symtab and enter them info the hash table |
| for (j = 0; j < n; j++, syms++) { |
| ENTRY item, *ret; |
| char *sym_name = symtab->strs + syms->st_name; |
| |
| // skip non-object and non-function symbols |
| int st_type = ELF_ST_TYPE(syms->st_info); |
| if ( st_type != STT_FUNC && st_type != STT_OBJECT) |
| continue; |
| // skip empty strings and undefined symbols |
| if (*sym_name == '\0' || syms->st_shndx == SHN_UNDEF) continue; |
| |
| symtab->symbols[j].name = sym_name; |
| symtab->symbols[j].offset = syms->st_value - baseaddr; |
| symtab->symbols[j].size = syms->st_size; |
| |
| item.key = sym_name; |
| item.data = (void *)&(symtab->symbols[j]); |
| |
| hsearch_r(item, ENTER, &ret, symtab->hash_table); |
| } |
| } |
| } |
| |
| // Look for a separate debuginfo file. |
| if (try_debuginfo) { |
| |
| // We prefer a debug symtab to an object's own symtab, so look in |
| // the debuginfo file. We stash a copy of the old symtab in case |
| // there is no debuginfo. |
| struct symtab* prev_symtab = symtab; |
| symtab = NULL; |
| |
| #ifdef NT_GNU_BUILD_ID |
| // First we look for a Build ID |
| for (cursct = shbuf, cnt = 0; |
| symtab == NULL && cnt < ehdr.e_shnum; |
| cnt++) { |
| if (cursct->sh_type == SHT_NOTE) { |
| Elf64_Nhdr *note = (Elf64_Nhdr *)scn_cache[cnt].c_data; |
| if (note->n_type == NT_GNU_BUILD_ID) { |
| symtab = build_symtab_from_build_id(note); |
| } |
| } |
| cursct++; |
| } |
| #endif |
| |
| // Then, if that doesn't work, the debug link |
| if (symtab == NULL) { |
| symtab = build_symtab_from_debug_link(filename, fd, &ehdr, shbuf, |
| scn_cache); |
| } |
| |
| // If we still haven't found a symtab, use the object's own symtab. |
| if (symtab != NULL) { |
| if (prev_symtab != NULL) |
| destroy_symtab(prev_symtab); |
| } else { |
| symtab = prev_symtab; |
| } |
| } |
| |
| quit: |
| if (shbuf) free(shbuf); |
| if (phbuf) free(phbuf); |
| if (scn_cache) { |
| for (cnt = 0; cnt < ehdr.e_shnum; cnt++) { |
| if (scn_cache[cnt].c_data != NULL) { |
| free(scn_cache[cnt].c_data); |
| } |
| } |
| free(scn_cache); |
| } |
| return symtab; |
| } |
| |
| struct symtab* build_symtab(int fd, const char *filename) { |
| return build_symtab_internal(fd, filename, /* try_debuginfo */ true); |
| } |
| |
| |
| void destroy_symtab(struct symtab* symtab) { |
| if (!symtab) return; |
| if (symtab->strs) free(symtab->strs); |
| if (symtab->symbols) free(symtab->symbols); |
| if (symtab->hash_table) { |
| hdestroy_r(symtab->hash_table); |
| free(symtab->hash_table); |
| } |
| free(symtab); |
| } |
| |
| uintptr_t search_symbol(struct symtab* symtab, uintptr_t base, |
| const char *sym_name, int *sym_size) { |
| ENTRY item; |
| ENTRY* ret = NULL; |
| |
| // library does not have symbol table |
| if (!symtab || !symtab->hash_table) |
| return (uintptr_t)NULL; |
| |
| item.key = (char*) strdup(sym_name); |
| item.data = NULL; |
| hsearch_r(item, FIND, &ret, symtab->hash_table); |
| if (ret) { |
| struct elf_symbol * sym = (struct elf_symbol *)(ret->data); |
| uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset); |
| if (sym_size) *sym_size = sym->size; |
| free(item.key); |
| return rslt; |
| } |
| |
| quit: |
| free(item.key); |
| return (uintptr_t) NULL; |
| } |
| |
| const char* nearest_symbol(struct symtab* symtab, uintptr_t offset, |
| uintptr_t* poffset) { |
| int n = 0; |
| if (!symtab) return NULL; |
| for (; n < symtab->num_symbols; n++) { |
| struct elf_symbol* sym = &(symtab->symbols[n]); |
| if (sym->name != NULL && |
| offset >= sym->offset && offset < sym->offset + sym->size) { |
| if (poffset) *poffset = (offset - sym->offset); |
| return sym->name; |
| } |
| } |
| return NULL; |
| } |
