• file
• revisions
• annotate
• diff
• comparison
• raw

agent/src/os/linux/symtab.c@8db2b3e46c38 (annotated)

agent/src/os/linux/symtab.c

Wed, 14 Jan 2009 19:45:01 -0800

author

swamyv

date

Wed, 14 Jan 2009 19:45:01 -0800

changeset 964

8db2b3e46c38

parent 435

a61af66fc99e

child 1729

7de45b5044c3

permissions

-rw-r--r--

6786948: SA on core file fails on solaris-amd64 if vm started with -XX:+StartAttachListener
Reviewed-by: jjh, dcubed

duke@435	1	/*
duke@435	2	* Copyright 2003-2005 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	#include <unistd.h>
duke@435	26	#include <sys/procfs.h>
duke@435	27	#include <search.h>
duke@435	28	#include <stdlib.h>
duke@435	29	#include <string.h>
duke@435	30	#include "symtab.h"
duke@435	31	#include "salibelf.h"
duke@435	32
duke@435	33
duke@435	34	// ----------------------------------------------------
duke@435	35	// functions for symbol lookups
duke@435	36	// ----------------------------------------------------
duke@435	37
duke@435	38	struct elf_section {
duke@435	39	ELF_SHDR *c_shdr;
duke@435	40	void *c_data;
duke@435	41	};
duke@435	42
duke@435	43	struct elf_symbol {
duke@435	44	char *name;
duke@435	45	uintptr_t offset;
duke@435	46	uintptr_t size;
duke@435	47	};
duke@435	48
duke@435	49	typedef struct symtab {
duke@435	50	char *strs;
duke@435	51	size_t num_symbols;
duke@435	52	struct elf_symbol *symbols;
duke@435	53	struct hsearch_data *hash_table;
duke@435	54	} symtab_t;
duke@435	55
duke@435	56	// read symbol table from given fd.
duke@435	57	struct symtab* build_symtab(int fd) {
duke@435	58	ELF_EHDR ehdr;
duke@435	59	char *names = NULL;
duke@435	60	struct symtab* symtab = NULL;
duke@435	61
duke@435	62	// Reading of elf header
duke@435	63	struct elf_section *scn_cache = NULL;
duke@435	64	int cnt = 0;
duke@435	65	ELF_SHDR* shbuf = NULL;
duke@435	66	ELF_SHDR* cursct = NULL;
duke@435	67	ELF_PHDR* phbuf = NULL;
duke@435	68	ELF_PHDR* phdr = NULL;
duke@435	69
duke@435	70	uintptr_t baseaddr = (uintptr_t)-1;
duke@435	71
duke@435	72	lseek(fd, (off_t)0L, SEEK_SET);
duke@435	73	if (! read_elf_header(fd, &ehdr)) {
duke@435	74	// not an elf
duke@435	75	return NULL;
duke@435	76	}
duke@435	77
duke@435	78	// read ELF header
duke@435	79	if ((shbuf = read_section_header_table(fd, &ehdr)) == NULL) {
duke@435	80	goto quit;
duke@435	81	}
duke@435	82
duke@435	83	baseaddr = find_base_address(fd, &ehdr);
duke@435	84
duke@435	85	scn_cache = (struct elf_section *)
duke@435	86	calloc(ehdr.e_shnum * sizeof(struct elf_section), 1);
duke@435	87	if (scn_cache == NULL) {
duke@435	88	goto quit;
duke@435	89	}
duke@435	90
duke@435	91	for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) {
duke@435	92	scn_cache[cnt].c_shdr = cursct;
duke@435	93	if (cursct->sh_type == SHT_SYMTAB || cursct->sh_type == SHT_STRTAB) {
duke@435	94	if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) {
duke@435	95	goto quit;
duke@435	96	}
duke@435	97	}
duke@435	98	cursct++;
duke@435	99	}
duke@435	100
duke@435	101	for (cnt = 1; cnt < ehdr.e_shnum; cnt++) {
duke@435	102	ELF_SHDR *shdr = scn_cache[cnt].c_shdr;
duke@435	103
duke@435	104	if (shdr->sh_type == SHT_SYMTAB) {
duke@435	105	ELF_SYM *syms;
duke@435	106	int j, n, rslt;
duke@435	107	size_t size;
duke@435	108
duke@435	109	// FIXME: there could be multiple data buffers associated with the
duke@435	110	// same ELF section. Here we can handle only one buffer. See man page
duke@435	111	// for elf_getdata on Solaris.
duke@435	112
duke@435	113	// guarantee(symtab == NULL, "multiple symtab");
duke@435	114	symtab = (struct symtab*)calloc(1, sizeof(struct symtab));
duke@435	115	if (symtab == NULL) {
duke@435	116	goto quit;
duke@435	117	}
duke@435	118	// the symbol table
duke@435	119	syms = (ELF_SYM *)scn_cache[cnt].c_data;
duke@435	120
duke@435	121	// number of symbols
duke@435	122	n = shdr->sh_size / shdr->sh_entsize;
duke@435	123
duke@435	124	// create hash table, we use hcreate_r, hsearch_r and hdestroy_r to
duke@435	125	// manipulate the hash table.
duke@435	126	symtab->hash_table = (struct hsearch_data*) calloc(1, sizeof(struct hsearch_data));
duke@435	127	rslt = hcreate_r(n, symtab->hash_table);
duke@435	128	// guarantee(rslt, "unexpected failure: hcreate_r");
duke@435	129
duke@435	130	// shdr->sh_link points to the section that contains the actual strings
duke@435	131	// for symbol names. the st_name field in ELF_SYM is just the
duke@435	132	// string table index. we make a copy of the string table so the
duke@435	133	// strings will not be destroyed by elf_end.
duke@435	134	size = scn_cache[shdr->sh_link].c_shdr->sh_size;
duke@435	135	symtab->strs = (char *)malloc(size);
duke@435	136	memcpy(symtab->strs, scn_cache[shdr->sh_link].c_data, size);
duke@435	137
duke@435	138	// allocate memory for storing symbol offset and size;
duke@435	139	symtab->num_symbols = n;
duke@435	140	symtab->symbols = (struct elf_symbol *)calloc(n , sizeof(struct elf_symbol));
duke@435	141
duke@435	142	// copy symbols info our symtab and enter them info the hash table
duke@435	143	for (j = 0; j < n; j++, syms++) {
duke@435	144	ENTRY item, *ret;
duke@435	145	char *sym_name = symtab->strs + syms->st_name;
duke@435	146
duke@435	147	// skip non-object and non-function symbols
duke@435	148	int st_type = ELF_ST_TYPE(syms->st_info);
duke@435	149	if ( st_type != STT_FUNC && st_type != STT_OBJECT)
duke@435	150	continue;
duke@435	151	// skip empty strings and undefined symbols
duke@435	152	if (*sym_name == '\0' || syms->st_shndx == SHN_UNDEF) continue;
duke@435	153
duke@435	154	symtab->symbols[j].name = sym_name;
duke@435	155	symtab->symbols[j].offset = syms->st_value - baseaddr;
duke@435	156	symtab->symbols[j].size = syms->st_size;
duke@435	157
duke@435	158	item.key = sym_name;
duke@435	159	item.data = (void *)&(symtab->symbols[j]);
duke@435	160
duke@435	161	hsearch_r(item, ENTER, &ret, symtab->hash_table);
duke@435	162	}
duke@435	163	}
duke@435	164	}
duke@435	165
duke@435	166	quit:
duke@435	167	if (shbuf) free(shbuf);
duke@435	168	if (phbuf) free(phbuf);
duke@435	169	if (scn_cache) {
duke@435	170	for (cnt = 0; cnt < ehdr.e_shnum; cnt++) {
duke@435	171	if (scn_cache[cnt].c_data != NULL) {
duke@435	172	free(scn_cache[cnt].c_data);
duke@435	173	}
duke@435	174	}
duke@435	175	free(scn_cache);
duke@435	176	}
duke@435	177	return symtab;
duke@435	178	}
duke@435	179
duke@435	180	void destroy_symtab(struct symtab* symtab) {
duke@435	181	if (!symtab) return;
duke@435	182	if (symtab->strs) free(symtab->strs);
duke@435	183	if (symtab->symbols) free(symtab->symbols);
duke@435	184	if (symtab->hash_table) {
duke@435	185	hdestroy_r(symtab->hash_table);
duke@435	186	free(symtab->hash_table);
duke@435	187	}
duke@435	188	free(symtab);
duke@435	189	}
duke@435	190
duke@435	191	uintptr_t search_symbol(struct symtab* symtab, uintptr_t base,
duke@435	192	const char *sym_name, int *sym_size) {
duke@435	193	ENTRY item;
duke@435	194	ENTRY* ret = NULL;
duke@435	195
duke@435	196	// library does not have symbol table
duke@435	197	if (!symtab || !symtab->hash_table)
duke@435	198	return (uintptr_t)NULL;
duke@435	199
duke@435	200	item.key = (char*) strdup(sym_name);
duke@435	201	hsearch_r(item, FIND, &ret, symtab->hash_table);
duke@435	202	if (ret) {
duke@435	203	struct elf_symbol * sym = (struct elf_symbol *)(ret->data);
duke@435	204	uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset);
duke@435	205	if (sym_size) *sym_size = sym->size;
duke@435	206	free(item.key);
duke@435	207	return rslt;
duke@435	208	}
duke@435	209
duke@435	210	quit:
duke@435	211	free(item.key);
duke@435	212	return (uintptr_t) NULL;
duke@435	213	}
duke@435	214
duke@435	215	const char* nearest_symbol(struct symtab* symtab, uintptr_t offset,
duke@435	216	uintptr_t* poffset) {
duke@435	217	int n = 0;
duke@435	218	if (!symtab) return NULL;
duke@435	219	for (; n < symtab->num_symbols; n++) {
duke@435	220	struct elf_symbol* sym = &(symtab->symbols[n]);
duke@435	221	if (sym->name != NULL &&
duke@435	222	offset >= sym->offset && offset < sym->offset + sym->size) {
duke@435	223	if (poffset) *poffset = (offset - sym->offset);
duke@435	224	return sym->name;
duke@435	225	}
duke@435	226	}
duke@435	227	return NULL;
duke@435	228	}