Author: kib
Date: Mon Aug 23 15:38:02 2010
New Revision: 211706
URL: http://svn.freebsd.org/changeset/base/211706
Log:
On shared object unload, in __cxa_finalize, call and clear all installed
atexit and __cxa_atexit handlers that are either installed by unloaded
dso, or points to the functions provided by the dso.
Use _rtld_addr_phdr to locate segment information from the address of
private variable belonging to the dso, supplied by crtstuff.c. Provide
utility function __elf_phdr_match_addr to do the match of address against
dso executable segment.
Call back into libthr from __cxa_finalize using weak
__pthread_cxa_finalize symbol to remove any atfork handler which
function points into unloaded object.
The rtld needs private __pthread_cxa_finalize symbol to not require
resolution of the weak undefined symbol at initialization time. This
cannot work, since rtld is relocated before sym_zero is set up.
Idea by: kan
Reviewed by: kan (previous version)
MFC after: 3 weeks
Added:
head/lib/libc/gen/elf_utils.c (contents, props changed)
Modified:
head/lib/libc/gen/Makefile.inc
head/lib/libc/gen/Symbol.map
head/lib/libc/include/libc_private.h
head/lib/libc/stdlib/atexit.c
head/lib/libthr/pthread.map
head/lib/libthr/thread/thr_fork.c
head/lib/libthr/thread/thr_private.h
head/libexec/rtld-elf/rtld.c
Modified: head/lib/libc/gen/Makefile.inc
==============================================================================
--- head/lib/libc/gen/Makefile.inc Mon Aug 23 15:27:03 2010
(r211705)
+++ head/lib/libc/gen/Makefile.inc Mon Aug 23 15:38:02 2010
(r211706)
@@ -10,7 +10,7 @@ SRCS+= __getosreldate.c __xuname.c \
alarm.c arc4random.c assert.c aux.c basename.c check_utility_compat.c \
clock.c closedir.c confstr.c \
crypt.c ctermid.c daemon.c devname.c dirname.c disklabel.c \
- dlfcn.c drand48.c erand48.c err.c errlst.c errno.c \
+ dlfcn.c drand48.c elf_utils.c erand48.c err.c errlst.c errno.c \
exec.c fdevname.c feature_present.c fmtcheck.c fmtmsg.c fnmatch.c \
fpclassify.c frexp.c fstab.c ftok.c fts.c fts-compat.c ftw.c \
getbootfile.c getbsize.c \
Modified: head/lib/libc/gen/Symbol.map
==============================================================================
--- head/lib/libc/gen/Symbol.map Mon Aug 23 15:27:03 2010
(r211705)
+++ head/lib/libc/gen/Symbol.map Mon Aug 23 15:38:02 2010
(r211706)
@@ -451,6 +451,7 @@ FBSDprivate_1.0 {
_rtld_atfork_post;
_rtld_error; /* for private use */
_rtld_thread_init; /* for private use */
+ __elf_phdr_match_addr;
_err;
_warn;
__fmtcheck;
Added: head/lib/libc/gen/elf_utils.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/lib/libc/gen/elf_utils.c Mon Aug 23 15:38:02 2010
(r211706)
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2010 Konstantin Belousov <k...@freebsd.org>
+ * 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. Neither the name of the author nor the names of any co-contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <link.h>
+
+int
+__elf_phdr_match_addr(struct dl_phdr_info *phdr_info, void *addr)
+{
+ const Elf_Phdr *ph;
+ int i;
+
+ for (i = 0; i < phdr_info->dlpi_phnum; i++) {
+ ph = &phdr_info->dlpi_phdr[i];
+ if (ph->p_type != PT_LOAD || (ph->p_flags & PF_X) == 0)
+ continue;
+ if (phdr_info->dlpi_addr + ph->p_vaddr <= (uintptr_t)addr &&
+ (uintptr_t)addr + sizeof(addr) < phdr_info->dlpi_addr +
+ ph->p_vaddr + ph->p_memsz)
+ break;
+ }
+ return (i != phdr_info->dlpi_phnum);
+}
Modified: head/lib/libc/include/libc_private.h
==============================================================================
--- head/lib/libc/include/libc_private.h Mon Aug 23 15:27:03 2010
(r211705)
+++ head/lib/libc/include/libc_private.h Mon Aug 23 15:38:02 2010
(r211706)
@@ -214,5 +214,7 @@ extern int __sys_fcntl(int, int, ...);
int _execvpe(const char *, char * const *, char * const *);
int _elf_aux_info(int aux, void *buf, int buflen);
+struct dl_phdr_info;
+int __elf_phdr_match_addr(struct dl_phdr_info *, void *);
#endif /* _LIBC_PRIVATE_H_ */
Modified: head/lib/libc/stdlib/atexit.c
==============================================================================
--- head/lib/libc/stdlib/atexit.c Mon Aug 23 15:27:03 2010
(r211705)
+++ head/lib/libc/stdlib/atexit.c Mon Aug 23 15:38:02 2010
(r211706)
@@ -37,6 +37,7 @@ static char sccsid[] = "@(#)atexit.c 8.2
__FBSDID("$FreeBSD$");
#include "namespace.h"
+#include <link.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
@@ -147,6 +148,9 @@ __cxa_atexit(void (*func)(void *), void
return (error);
}
+#pragma weak __pthread_cxa_finalize
+void __pthread_cxa_finalize(const struct dl_phdr_info *);
+
/*
* Call all handlers registered with __cxa_atexit for the shared
* object owning 'dso'. Note: if 'dso' is NULL, then all remaining
@@ -155,18 +159,28 @@ __cxa_atexit(void (*func)(void *), void
void
__cxa_finalize(void *dso)
{
+ struct dl_phdr_info phdr_info;
struct atexit *p;
struct atexit_fn fn;
- int n;
+ int n, has_phdr;
+
+ if (dso != NULL)
+ has_phdr = _rtld_addr_phdr(dso, &phdr_info);
+ else
+ has_phdr = 0;
_MUTEX_LOCK(&atexit_mutex);
for (p = __atexit; p; p = p->next) {
for (n = p->ind; --n >= 0;) {
if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
continue; /* already been called */
- if (dso != NULL && dso != p->fns[n].fn_dso)
- continue; /* wrong DSO */
fn = p->fns[n];
+ if (dso != NULL && dso != fn.fn_dso) {
+ /* wrong DSO ? */
+ if (!has_phdr || !__elf_phdr_match_addr(
+ &phdr_info, fn.fn_ptr.cxa_func))
+ continue;
+ }
/*
Mark entry to indicate that this particular handler
has already been called.
@@ -185,4 +199,7 @@ __cxa_finalize(void *dso)
_MUTEX_UNLOCK(&atexit_mutex);
if (dso == NULL)
_MUTEX_DESTROY(&atexit_mutex);
+
+ if (&__pthread_cxa_finalize != NULL)
+ __pthread_cxa_finalize(&phdr_info);
}
Modified: head/lib/libthr/pthread.map
==============================================================================
--- head/lib/libthr/pthread.map Mon Aug 23 15:27:03 2010 (r211705)
+++ head/lib/libthr/pthread.map Mon Aug 23 15:38:02 2010 (r211706)
@@ -192,6 +192,7 @@ FBSDprivate_1.0 {
__poll;
__pthread_cond_timedwait;
__pthread_cond_wait;
+ __pthread_cxa_finalize;
__pthread_mutex_init;
__pthread_mutex_lock;
__pthread_mutex_timedlock;
Modified: head/lib/libthr/thread/thr_fork.c
==============================================================================
--- head/lib/libthr/thread/thr_fork.c Mon Aug 23 15:27:03 2010
(r211705)
+++ head/lib/libthr/thread/thr_fork.c Mon Aug 23 15:38:02 2010
(r211706)
@@ -59,6 +59,7 @@
#include "namespace.h"
#include <errno.h>
+#include <link.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
@@ -94,6 +95,27 @@ _pthread_atfork(void (*prepare)(void), v
return (0);
}
+void
+__pthread_cxa_finalize(struct dl_phdr_info *phdr_info)
+{
+ struct pthread *curthread;
+ struct pthread_atfork *af, *af1;
+
+ _thr_check_init();
+
+ curthread = _get_curthread();
+ THR_UMUTEX_LOCK(curthread, &_thr_atfork_lock);
+ TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) {
+ if (__elf_phdr_match_addr(phdr_info, af->prepare) ||
+ __elf_phdr_match_addr(phdr_info, af->parent) ||
+ __elf_phdr_match_addr(phdr_info, af->child)) {
+ TAILQ_REMOVE(&_thr_atfork_list, af, qe);
+ free(af);
+ }
+ }
+ THR_UMUTEX_UNLOCK(curthread, &_thr_atfork_lock);
+}
+
__weak_reference(_fork, fork);
pid_t _fork(void);
Modified: head/lib/libthr/thread/thr_private.h
==============================================================================
--- head/lib/libthr/thread/thr_private.h Mon Aug 23 15:27:03 2010
(r211705)
+++ head/lib/libthr/thread/thr_private.h Mon Aug 23 15:38:02 2010
(r211706)
@@ -740,6 +740,9 @@ _thr_check_init(void)
_libpthread_init(NULL);
}
+struct dl_phdr_info;
+void __pthread_cxa_finalize(struct dl_phdr_info *phdr_info);
+
__END_DECLS
#endif /* !_THR_PRIVATE_H */
Modified: head/libexec/rtld-elf/rtld.c
==============================================================================
--- head/libexec/rtld-elf/rtld.c Mon Aug 23 15:27:03 2010
(r211705)
+++ head/libexec/rtld-elf/rtld.c Mon Aug 23 15:38:02 2010
(r211706)
@@ -3692,6 +3692,10 @@ fetch_ventry(const Obj_Entry *obj, unsig
return NULL;
}
+/*
+ * Overrides for libc_pic-provided functions.
+ */
+
int
__getosreldate(void)
{
@@ -3711,3 +3715,11 @@ __getosreldate(void)
osreldate = osrel;
return (osreldate);
}
+
+/*
+ * No unresolved symbols for rtld.
+ */
+void
+__pthread_cxa_finalize(struct dl_phdr_info *a)
+{
+}
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