Attachment 178484 Details for Bug 215709 – Provide __cxa_thread_atexit_impl(), split __cxa_thread_atexit() into separate .o.

[patch] Provide __cxa_thread_atexit_impl(), split __cxa_thread_atexit() into separate .o.

1.patch (text/plain), 10.28 KB, created by Konstantin Belousov on 2017-01-03 17:03:41 UTC

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Creator: Konstantin Belousov

Created: 2017-01-03 17:03:41 UTC

Size: 10.28 KB

patch

obsolete

>diff --git a/lib/libc/include/libc_private.h b/lib/libc/include/libc_private.h
>index 972eb2938ed..74a7e3a841b 100644
>--- a/lib/libc/include/libc_private.h
>+++ b/lib/libc/include/libc_private.h
>@@ -272,6 +272,8 @@ void _malloc_thread_cleanup(void);
>  * thread is exiting, so its thread-local dtors should be called.
>  */
> void __cxa_thread_call_dtors(void);
>+int __cxa_thread_atexit_hidden(void (*dtor_func)(void *), void *obj,
>+    void *dso_symbol) __hidden;
> 
> /*
>  * These functions are used by the threading libraries in order to protect
>diff --git a/lib/libc/stdlib/Makefile.inc b/lib/libc/stdlib/Makefile.inc
>index 935f3ffb35f..00f90e2f81e 100644
>--- a/lib/libc/stdlib/Makefile.inc
>+++ b/lib/libc/stdlib/Makefile.inc
>@@ -5,7 +5,9 @@
> .PATH: ${LIBC_SRCTOP}/${LIBC_ARCH}/stdlib ${LIBC_SRCTOP}/stdlib
> 
> MISRCS+=C99_Exit.c a64l.c abort.c abs.c atexit.c atof.c atoi.c atol.c atoll.c \
>-	bsearch.c cxa_thread_atexit.c div.c exit.c getenv.c getopt.c getopt_long.c \
>+	bsearch.c \
>+	cxa_thread_atexit.c cxa_thread_atexit_impl.c \
>+	div.c exit.c getenv.c getopt.c getopt_long.c \
> 	getsubopt.c hcreate.c hcreate_r.c hdestroy_r.c heapsort.c heapsort_b.c \
> 	hsearch_r.c imaxabs.c imaxdiv.c \
> 	insque.c l64a.c labs.c ldiv.c llabs.c lldiv.c lsearch.c \
>diff --git a/lib/libc/stdlib/Symbol.map b/lib/libc/stdlib/Symbol.map
>index 6cdc38e8a68..a239a42018d 100644
>--- a/lib/libc/stdlib/Symbol.map
>+++ b/lib/libc/stdlib/Symbol.map
>@@ -118,6 +118,7 @@ FBSD_1.4 {
> 
> FBSD_1.5 {
> 	__cxa_thread_atexit;
>+	__cxa_thread_atexit_impl;
> };
> 
> FBSDprivate_1.0 {
>diff --git a/lib/libc/stdlib/cxa_thread_atexit.c b/lib/libc/stdlib/cxa_thread_atexit.c
>index c9667313670..6f03ef0d323 100644
>--- a/lib/libc/stdlib/cxa_thread_atexit.c
>+++ b/lib/libc/stdlib/cxa_thread_atexit.c
>@@ -1,7 +1,10 @@
> /*-
>- * Copyright (c) 2016 Mahdi Mokhtari <mokhi64@gmail.com>
>+ * Copyright (c) 2017 The FreeBSD Foundation
>  * All rights reserved.
>  *
>+ * Portions of this software were developed by Konstantin Belousov
>+ * under sponsorship from the FreeBSD Foundation.
>+ *
>  * Redistribution and use in source and binary forms, with or without
>  * modification, are permitted provided that the following conditions
>  * are met:
>@@ -27,114 +30,11 @@
> #include <sys/cdefs.h>
> __FBSDID("$FreeBSD$");
> 
>-#include <sys/queue.h>
>-#include "namespace.h"
>-#include <errno.h>
>-#include <link.h>
>-#include <pthread.h>
>-#include <stddef.h>
>-#include <stdlib.h>
>-#include <stdio.h>
>-#include "un-namespace.h"
> #include "libc_private.h"
> 
>-/*
>- * C++11 introduces the thread_local scope (like __thread with some
>- * additions).  As a key-feature it should support non-trivial
>- * destructors, registered with __cxa_thread_atexit() to be executed
>- * at the thread termination.
>- *
>- * The implemention keeps a _Thread_local list of destructors per each
>- * thread, and calls __cxa_thread_call_dtors() on each thread's exit
>- * to do cleanup.  For a thread calling exit(3), in particular, for
>- * the initial thread returning from main(), we call
>- * __cxa_thread_call_dtors() inside exit().
>- *
>- * It could be possible that a dynamically loaded library, use
>- * thread_local variable but is dlclose()'d before thread exit.  The
>- * destructor of this variable will then try to access the address,
>- * for calling it but it's unloaded, so it'll crash.  We're using
>- * __elf_phdr_match_addr() to detect and prevent such cases and so
>- * prevent the crash.
>- */
>-
>-#define CXA_DTORS_ITERATIONS 4
>-
>-struct cxa_thread_dtor {
>-	void *obj;
>-	void (*func)(void *);
>-	void *dso;
>-	LIST_ENTRY(cxa_thread_dtor) entry;
>-};
>-static _Thread_local LIST_HEAD(dtor_list, cxa_thread_dtor) dtors =
>-    LIST_HEAD_INITIALIZER(dtors);
>-
> int
> __cxa_thread_atexit(void (*dtor_func)(void *), void *obj, void *dso_symbol)
> {
>-	struct cxa_thread_dtor *new_dtor;
>-
>-	new_dtor = malloc(sizeof(*new_dtor));
>-	if (new_dtor == NULL) {
>-		errno = ENOMEM; /* forcibly override malloc(3) error */
>-		return (-1);
>-	}
>-
>-	new_dtor->obj = obj;
>-	new_dtor->func = dtor_func;
>-	new_dtor->dso = dso_symbol;
>-	LIST_INSERT_HEAD(&dtors, new_dtor, entry);
>-	return (0);
>-}
>-
>-static void
>-walk_cb_call(struct cxa_thread_dtor *dtor)
>-{
>-	struct dl_phdr_info phdr_info;
>-
>-	if (_rtld_addr_phdr(dtor->dso, &phdr_info) &&
>-	    __elf_phdr_match_addr(&phdr_info, dtor->func))
>-		dtor->func(dtor->obj);
>-	else
>-		fprintf(stderr, "__cxa_thread_call_dtors: dtr %p from "
>-		    "unloaded dso, skipping\n", (void *)(dtor->func));
>-}
>-
>-static void
>-walk_cb_nocall(struct cxa_thread_dtor *dtor __unused)
>-{
>-}
>-
>-static void
>-cxa_thread_walk(void (*cb)(struct cxa_thread_dtor *))
>-{
>-	struct cxa_thread_dtor *dtor, *tdtor;
>-
>-	LIST_FOREACH_SAFE(dtor, &dtors, entry, tdtor) {
>-		LIST_REMOVE(dtor, entry);
>-		cb(dtor);
>-		free(dtor);
>-	}
>-}
>-
>-/*
>- * This is the callback function we use to call destructors, once for
>- * each thread.  It is called in exit(3) in libc/stdlib/exit.c and
>- * before exit_thread() in libthr/thread/thr_exit.c.
>- */
>-void
>-__cxa_thread_call_dtors(void)
>-{
>-	int i;
>-
>-	for (i = 0; i < CXA_DTORS_ITERATIONS && !LIST_EMPTY(&dtors); i++)
>-		cxa_thread_walk(walk_cb_call);
> 
>-	if (!LIST_EMPTY(&dtors)) {
>-		fprintf(stderr, "Thread %p is exiting with more "
>-		    "thread-specific dtors created after %d iterations "
>-		    "of destructor calls\n",
>-		    _pthread_self(), i);
>-		cxa_thread_walk(walk_cb_nocall);
>-	}
>+	return (__cxa_thread_atexit_hidden(dtor_func, obj, dso_symbol));
> }
>diff --git a/lib/libc/stdlib/cxa_thread_atexit_impl.c b/lib/libc/stdlib/cxa_thread_atexit_impl.c
>new file mode 100644
>index 00000000000..0f0a7a314fa
>--- /dev/null
>+++ b/lib/libc/stdlib/cxa_thread_atexit_impl.c
>@@ -0,0 +1,153 @@
>+/*-
>+ * Copyright (c) 2016 Mahdi Mokhtari <mokhi64@gmail.com>
>+ * Copyright (c) 2016, 2017 The FreeBSD Foundation
>+ * All rights reserved.
>+ *
>+ * Portions of this software were developed by Konstantin Belousov
>+ * under sponsorship from the FreeBSD Foundation.
>+ *
>+ * 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$");
>+
>+#include <sys/queue.h>
>+#include "namespace.h"
>+#include <errno.h>
>+#include <link.h>
>+#include <pthread.h>
>+#include <stddef.h>
>+#include <stdlib.h>
>+#include <stdio.h>
>+#include "un-namespace.h"
>+#include "libc_private.h"
>+
>+/*
>+ * C++11 introduces the thread_local scope (like __thread with some
>+ * additions).  As a key-feature it should support non-trivial
>+ * destructors, registered with __cxa_thread_atexit() to be executed
>+ * at the thread termination.
>+ *
>+ * The implemention keeps a _Thread_local list of destructors per each
>+ * thread, and calls __cxa_thread_call_dtors() on each thread's exit
>+ * to do cleanup.  For a thread calling exit(3), in particular, for
>+ * the initial thread returning from main(), we call
>+ * __cxa_thread_call_dtors() inside exit().
>+ *
>+ * It could be possible that a dynamically loaded library, use
>+ * thread_local variable but is dlclose()'d before thread exit.  The
>+ * destructor of this variable will then try to access the address,
>+ * for calling it but it's unloaded, so it'll crash.  We're using
>+ * __elf_phdr_match_addr() to detect and prevent such cases and so
>+ * prevent the crash.
>+ */
>+
>+#define CXA_DTORS_ITERATIONS 4
>+
>+struct cxa_thread_dtor {
>+	void *obj;
>+	void (*func)(void *);
>+	void *dso;
>+	LIST_ENTRY(cxa_thread_dtor) entry;
>+};
>+static _Thread_local LIST_HEAD(dtor_list, cxa_thread_dtor) dtors =
>+    LIST_HEAD_INITIALIZER(dtors);
>+
>+int
>+__cxa_thread_atexit_impl(void (*dtor_func)(void *), void *obj,
>+    void *dso_symbol)
>+{
>+
>+	return (__cxa_thread_atexit_hidden(dtor_func, obj, dso_symbol));
>+}
>+
>+int
>+__cxa_thread_atexit_hidden(void (*dtor_func)(void *), void *obj,
>+    void *dso_symbol)
>+{
>+	struct cxa_thread_dtor *new_dtor;
>+
>+	new_dtor = malloc(sizeof(*new_dtor));
>+	if (new_dtor == NULL) {
>+		errno = ENOMEM; /* forcibly override malloc(3) error */
>+		return (-1);
>+	}
>+
>+	new_dtor->obj = obj;
>+	new_dtor->func = dtor_func;
>+	new_dtor->dso = dso_symbol;
>+	LIST_INSERT_HEAD(&dtors, new_dtor, entry);
>+	return (0);
>+}
>+
>+static void
>+walk_cb_call(struct cxa_thread_dtor *dtor)
>+{
>+	struct dl_phdr_info phdr_info;
>+
>+	if (_rtld_addr_phdr(dtor->dso, &phdr_info) &&
>+	    __elf_phdr_match_addr(&phdr_info, dtor->func))
>+		dtor->func(dtor->obj);
>+	else
>+		fprintf(stderr, "__cxa_thread_call_dtors: dtr %p from "
>+		    "unloaded dso, skipping\n", (void *)(dtor->func));
>+}
>+
>+static void
>+walk_cb_nocall(struct cxa_thread_dtor *dtor __unused)
>+{
>+}
>+
>+static void
>+cxa_thread_walk(void (*cb)(struct cxa_thread_dtor *))
>+{
>+	struct cxa_thread_dtor *dtor, *tdtor;
>+
>+	LIST_FOREACH_SAFE(dtor, &dtors, entry, tdtor) {
>+		LIST_REMOVE(dtor, entry);
>+		cb(dtor);
>+		free(dtor);
>+	}
>+}
>+
>+/*
>+ * This is the callback function we use to call destructors, once for
>+ * each thread.  It is called in exit(3) in libc/stdlib/exit.c and
>+ * before exit_thread() in libthr/thread/thr_exit.c.
>+ */
>+void
>+__cxa_thread_call_dtors(void)
>+{
>+	int i;
>+
>+	for (i = 0; i < CXA_DTORS_ITERATIONS && !LIST_EMPTY(&dtors); i++)
>+		cxa_thread_walk(walk_cb_call);
>+
>+	if (!LIST_EMPTY(&dtors)) {
>+		fprintf(stderr, "Thread %p is exiting with more "
>+		    "thread-specific dtors created after %d iterations "
>+		    "of destructor calls\n",
>+		    _pthread_self(), i);
>+		cxa_thread_walk(walk_cb_nocall);
>+	}
>+}

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Attachments on bug 215709: 178484