diff -r db5bf5438c0a -r dc90c239f4ec hotspot/agent/src/os/bsd/symtab.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/hotspot/agent/src/os/bsd/symtab.c Sun Sep 25 16:03:29 2011 -0700 @@ -0,0 +1,239 @@ +/* + * Copyright (c) 2003, 2010, 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 +#include +#include +#include +#include +#include +#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; + DB* hash_table; +} symtab_t; + +// read symbol table from given fd. +struct symtab* build_symtab(int fd) { + ELF_EHDR ehdr; + 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; + int symtab_found = 0; + int dynsym_found = 0; + uint32_t symsection = SHT_SYMTAB; + + 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 = calloc(ehdr.e_shnum, sizeof(*scn_cache)); + 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_DYNSYM) { + if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) { + goto quit; + } + } + + if (cursct->sh_type == SHT_SYMTAB) + symtab_found++; + + if (cursct->sh_type == SHT_DYNSYM) + dynsym_found++; + + cursct++; + } + + if (!symtab_found && dynsym_found) + symsection = SHT_DYNSYM; + + for (cnt = 1; cnt < ehdr.e_shnum; cnt++) { + ELF_SHDR *shdr = scn_cache[cnt].c_shdr; + + if (shdr->sh_type == symsection) { + 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 = calloc(1, sizeof(*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 berkeley db to + // manipulate the hash table. + symtab->hash_table = dbopen(NULL, O_CREAT | O_RDWR, 0600, DB_HASH, NULL); + // guarantee(symtab->hash_table, "unexpected failure: dbopen"); + + // 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 = 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 = calloc(n , sizeof(*symtab->symbols)); + + // copy symbols info our symtab and enter them info the hash table + for (j = 0; j < n; j++, syms++) { + DBT key, value; + 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; + + key.data = sym_name; + key.size = strlen(sym_name) + 1; + value.data = &(symtab->symbols[j]); + value.size = sizeof(void *); + (*symtab->hash_table->put)(symtab->hash_table, &key, &value, 0); + } + } + } + +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; +} + +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) { + symtab->hash_table->close(symtab->hash_table); + } + free(symtab); +} + +uintptr_t search_symbol(struct symtab* symtab, uintptr_t base, + const char *sym_name, int *sym_size) { + DBT key, value; + int ret; + + // library does not have symbol table + if (!symtab || !symtab->hash_table) + return 0; + + key.data = (char*)(uintptr_t)sym_name; + key.size = strlen(sym_name) + 1; + ret = (*symtab->hash_table->get)(symtab->hash_table, &key, &value, 0); + if (ret == 0) { + struct elf_symbol *sym = value.data; + uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset); + if (sym_size) *sym_size = sym->size; + return rslt; + } + +quit: + return 0; +} + +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; +}