freebsd-dev/lib/libc/gen/dlfcn.c
Konstantin Belousov 22517af2c1 dl_iterate_phdr(3): provide exclusive locking for callback when statically linked.
Apparently llvm unwinder depends on the external locking for callback.

Reviewed by:	cem, emaste
Tested by:	emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D26109
2020-08-20 15:19:09 +00:00

272 lines
6.0 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 1998 John D. Polstra
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#if !defined(IN_LIBDL) || defined(PIC)
/*
* Linkage to services provided by the dynamic linker.
*/
#include <sys/mman.h>
#include <dlfcn.h>
#include <link.h>
#include <stddef.h>
#include "namespace.h"
#include <pthread.h>
#include "un-namespace.h"
#include "libc_private.h"
#include "reentrant.h"
static char sorry[] = "Service unavailable";
void _rtld_thread_init(void *);
void _rtld_atfork_pre(int *);
void _rtld_atfork_post(int *);
/*
* For ELF, the dynamic linker directly resolves references to its
* services to functions inside the dynamic linker itself. These
* weak-symbol stubs are necessary so that "ld" won't complain about
* undefined symbols. The stubs are executed only when the program is
* linked statically, or when a given service isn't implemented in the
* dynamic linker. They must return an error if called, and they must
* be weak symbols so that the dynamic linker can override them.
*/
#pragma weak _rtld_error
void
_rtld_error(const char *fmt __unused, ...)
{
}
#pragma weak dladdr
int
dladdr(const void *addr __unused, Dl_info *dlip __unused)
{
_rtld_error(sorry);
return (0);
}
#pragma weak dlclose
int
dlclose(void *handle __unused)
{
_rtld_error(sorry);
return (-1);
}
#pragma weak dlerror
char *
dlerror(void)
{
return (sorry);
}
#pragma weak dllockinit
void
dllockinit(void *context,
void *(*lock_create)(void *context) __unused,
void (*rlock_acquire)(void *lock) __unused,
void (*wlock_acquire)(void *lock) __unused,
void (*lock_release)(void *lock) __unused,
void (*lock_destroy)(void *lock) __unused,
void (*context_destroy)(void *context) __unused)
{
if (context_destroy != NULL)
context_destroy(context);
}
#pragma weak dlopen
void *
dlopen(const char *name __unused, int mode __unused)
{
_rtld_error(sorry);
return (NULL);
}
#pragma weak dlsym
void *
dlsym(void * __restrict handle __unused, const char * __restrict name __unused)
{
_rtld_error(sorry);
return (NULL);
}
#pragma weak dlfunc
dlfunc_t
dlfunc(void * __restrict handle __unused, const char * __restrict name __unused)
{
_rtld_error(sorry);
return (NULL);
}
#pragma weak dlvsym
void *
dlvsym(void * __restrict handle __unused, const char * __restrict name __unused,
const char * __restrict version __unused)
{
_rtld_error(sorry);
return (NULL);
}
#pragma weak dlinfo
int
dlinfo(void * __restrict handle __unused, int request __unused,
void * __restrict p __unused)
{
_rtld_error(sorry);
return (0);
}
#pragma weak _rtld_thread_init
void
_rtld_thread_init(void *li __unused)
{
_rtld_error(sorry);
}
#ifndef IN_LIBDL
static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT;
static struct dl_phdr_info phdr_info;
static mutex_t dl_phdr_info_lock = MUTEX_INITIALIZER;
static void
dl_init_phdr_info(void)
{
Elf_Auxinfo *auxp;
unsigned int i;
for (auxp = __elf_aux_vector; auxp->a_type != AT_NULL; auxp++) {
switch (auxp->a_type) {
case AT_BASE:
phdr_info.dlpi_addr = (Elf_Addr)auxp->a_un.a_ptr;
break;
case AT_EXECPATH:
phdr_info.dlpi_name = (const char *)auxp->a_un.a_ptr;
break;
case AT_PHDR:
phdr_info.dlpi_phdr =
(const Elf_Phdr *)auxp->a_un.a_ptr;
break;
case AT_PHNUM:
phdr_info.dlpi_phnum = (Elf_Half)auxp->a_un.a_val;
break;
}
}
for (i = 0; i < phdr_info.dlpi_phnum; i++) {
if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) {
phdr_info.dlpi_tls_modid = 1;
phdr_info.dlpi_tls_data =
(void*)phdr_info.dlpi_phdr[i].p_vaddr;
}
}
phdr_info.dlpi_adds = 1;
}
#endif
#pragma weak dl_iterate_phdr
int
dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *) __unused,
void *data __unused)
{
#ifndef IN_LIBDL
int ret;
__init_elf_aux_vector();
if (__elf_aux_vector == NULL)
return (1);
_once(&dl_phdr_info_once, dl_init_phdr_info);
mutex_lock(&dl_phdr_info_lock);
ret = callback(&phdr_info, sizeof(phdr_info), data);
mutex_unlock(&dl_phdr_info_lock);
return (ret);
#else
return (0);
#endif
}
#pragma weak fdlopen
void *
fdlopen(int fd __unused, int mode __unused)
{
_rtld_error(sorry);
return (NULL);
}
#pragma weak _rtld_atfork_pre
void
_rtld_atfork_pre(int *locks __unused)
{
}
#pragma weak _rtld_atfork_post
void
_rtld_atfork_post(int *locks __unused)
{
}
#pragma weak _rtld_addr_phdr
int
_rtld_addr_phdr(const void *addr __unused,
struct dl_phdr_info *phdr_info_a __unused)
{
return (0);
}
#pragma weak _rtld_get_stack_prot
int
_rtld_get_stack_prot(void)
{
return (PROT_EXEC | PROT_READ | PROT_WRITE);
}
#pragma weak _rtld_is_dlopened
int
_rtld_is_dlopened(void *arg __unused)
{
return (0);
}
#endif /* !defined(IN_LIBDL) || defined(PIC) */