OpenSolaris_b135/lib/libtnfctl/elf.c
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 1994, by Sun Microsytems, Inc.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* Interfaces for searching for elf specific information
*/
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <link.h>
#include <sys/procfs.h>
#include "tnfctl_int.h"
#include "dbg.h"
/*
* Declarations
*/
static tnfctl_errcode_t dynsec_num(tnfctl_handle_t *hndl, uintptr_t baseaddr,
int objfd, int *num_dyn);
static tnfctl_errcode_t elf_dynmatch(Elf *elf, char *strs, Elf_Scn *dyn_scn,
GElf_Shdr *dyn_shdr, Elf_Data *dyn_data,
uintptr_t baseaddr, tnfctl_elf_search_t * search_info_p);
static tnfctl_errcode_t dyn_findtag(
Elf3264_Dyn *start, /* start of dynam table read in */
Elf3264_Sword tag, /* tag to search for */
uintptr_t dynam_addr, /* address of _DYNAMIC in target */
int limit, /* number of entries in table */
uintptr_t *dentry_address); /* return value */
/* ---------------------------------------------------------------- */
/* ----------------------- Public Functions ----------------------- */
/* ---------------------------------------------------------------- */
/*
* _tnfctl_elf_dbgent() - this function finds the address of the
* debug struct (DT_DEBUG) in the target process. _DYNAMIC is a symbol
* present in every object. The one in the main executable references
* an array that is tagged with the kind of each member. We search
* for the tag of DT_DEBUG which is where the run time linker maintains
* a structure that references the shared object linked list.
*
* A side effect of searching for DT_DEBUG ensures that the executable is
* a dynamic executable - tracing only works on dynamic executables because
* static executables don't have relocation tables.
*/
tnfctl_errcode_t
_tnfctl_elf_dbgent(tnfctl_handle_t *hndl, uintptr_t * entaddr_p)
{
tnfctl_errcode_t prexstat = TNFCTL_ERR_NONE;
prb_status_t prbstat = PRB_STATUS_OK;
int miscstat;
int objfd;
int num_dynentries = 0;
uintptr_t dynamic_addr;
uintptr_t baseaddr;
uintptr_t dentry_addr;
Elf3264_Dyn *dynam_tab = NULL;
long dynam_tab_size;
*entaddr_p = NULL;
prbstat = prb_mainobj_get(hndl->proc_p, &objfd, &baseaddr);
if (prbstat)
return (_tnfctl_map_to_errcode(prbstat));
/* find the address of the symbol _DYNAMIC */
prexstat = _tnfctl_sym_find_in_obj(objfd, baseaddr, "_DYNAMIC",
&dynamic_addr);
if (prexstat) {
prexstat = TNFCTL_ERR_NOTDYNAMIC;
goto Cleanup;
}
/* find the number of entries in the .dynamic section */
prexstat = dynsec_num(hndl, baseaddr, objfd, &num_dynentries);
if (prexstat)
goto Cleanup;
DBG_TNF_PROBE_2(_tnfctl_elf_dbgent_1, "libtnfctl", "sunw%verbosity 2",
tnf_long, num_of_dynentries, num_dynentries,
tnf_opaque, DYNAMIC_address, dynamic_addr);
/* read in the dynamic table from the image of the process */
dynam_tab_size = num_dynentries * sizeof (Elf3264_Dyn);
dynam_tab = malloc(dynam_tab_size);
if (!dynam_tab) {
close(objfd);
return (TNFCTL_ERR_ALLOCFAIL);
}
miscstat = hndl->p_read(hndl->proc_p, dynamic_addr, dynam_tab,
dynam_tab_size);
if (miscstat) {
prexstat = TNFCTL_ERR_INTERNAL;
goto Cleanup;
}
prexstat = dyn_findtag(dynam_tab, DT_DEBUG, dynamic_addr,
num_dynentries, &dentry_addr);
if (prexstat) {
goto Cleanup;
}
*entaddr_p = dentry_addr;
Cleanup:
close(objfd);
if (dynam_tab)
free(dynam_tab);
return (prexstat);
}
/* ---------------------------------------------------------------- */
/* ----------------------- Private Functions ---------------------- */
/* ---------------------------------------------------------------- */
/*
* dyn_findtag() - searches tags in _DYNAMIC table
*/
static tnfctl_errcode_t
dyn_findtag(Elf3264_Dyn * start, /* start of dynam table read in */
Elf3264_Sword tag, /* tag to search for */
uintptr_t dynam_addr, /* base address of _DYNAMIC in target */
int limit, /* number of entries in table */
uintptr_t * dentry_address)
{ /* return value */
Elf3264_Dyn *dp;
for (dp = start; dp->d_tag != DT_NULL; dp++) {
DBG_TNF_PROBE_1(dyn_findtag_1, "libtnfctl",
"sunw%verbosity 3; sunw%debug 'in loop'",
tnf_long, tag, dp->d_tag);
if (dp->d_tag == tag) {
*dentry_address = dynam_addr +
(dp - start) * sizeof (Elf3264_Dyn);
return (TNFCTL_ERR_NONE);
}
if (--limit <= 0) {
DBG((void) fprintf(stderr,
"dyn_findtag: exceeded limit of table\n"));
return (TNFCTL_ERR_INTERNAL);
}
}
DBG((void) fprintf(stderr,
"dyn_findtag: couldn't find tag, last tag=%d\n",
(int) dp->d_tag));
return (TNFCTL_ERR_INTERNAL);
}
/*
* dynsec_num() - find the number of entries in the .dynamic section
*/
/*ARGSUSED*/
static tnfctl_errcode_t
dynsec_num(tnfctl_handle_t *hndl, uintptr_t baseaddr,
int objfd, int *num_dyn)
{
int num_ent = 0;
tnfctl_errcode_t prexstat;
tnfctl_elf_search_t search_info;
DBG_TNF_PROBE_0(dynsec_num_1, "libtnfctl",
"sunw%verbosity 2;"
"sunw%debug 'counting number of entries in .dynamic section'");
search_info.section_func = elf_dynmatch;
search_info.section_data = &num_ent;
prexstat = _tnfctl_traverse_object(objfd, baseaddr, &search_info);
if (prexstat)
return (prexstat);
if (num_ent == 0)
return (TNFCTL_ERR_NOTDYNAMIC);
*num_dyn = num_ent;
return (TNFCTL_ERR_NONE);
}
/*
* elf_dynmatch() - this function searches for the .dynamic section and
* returns the number of entries in it.
*/
/*ARGSUSED*/
static tnfctl_errcode_t
elf_dynmatch(Elf * elf,
char *strs,
Elf_Scn * dyn_scn,
GElf_Shdr * dyn_shdr,
Elf_Data * dyn_data,
uintptr_t baseaddr,
tnfctl_elf_search_t *search_info_p)
{
char *scn_name;
int *ret = (int *) search_info_p->section_data;
/* bail if this isn't a .dynamic section */
scn_name = strs + dyn_shdr->sh_name;
if (strcmp(scn_name, ".dynamic") != 0)
return (TNFCTL_ERR_NONE);
if (dyn_shdr->sh_entsize == 0) { /* no dynamic section */
*ret = 0;
} else {
*ret = (int) (dyn_shdr->sh_size / dyn_shdr->sh_entsize);
}
return (TNFCTL_ERR_NONE);
}