1 files changed, 301 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_rtld.c b/lib/libthr/thread/thr_rtld.c
new file mode 100644
index 000000000000..3cfdfc548cf2
--- /dev/null
+++ b/lib/libthr/thread/thr_rtld.c
@@ -0,0 +1,301 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2006, David Xu <davidxu@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 unmodified, 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 ``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 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.
+ */
+
+ /*
+  * A lockless rwlock for rtld.
+  */
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <link.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libc_private.h"
+#include "rtld_lock.h"
+#include "thr_private.h"
+
+extern int __libsys_errno;
+
+static int	_thr_rtld_clr_flag(int);
+static void	*_thr_rtld_lock_create(void);
+static void	_thr_rtld_lock_destroy(void *);
+static void	_thr_rtld_lock_release(void *);
+static void	_thr_rtld_rlock_acquire(void *);
+static int	_thr_rtld_set_flag(int);
+static void	_thr_rtld_wlock_acquire(void *);
+
+struct rtld_lock {
+	struct urwlock lock;
+	struct pthread *wowner;
+	u_int rlocks;
+	char _pad[CACHE_LINE_SIZE - sizeof(struct urwlock) -
+	    sizeof(struct pthread *) - sizeof(u_int)];
+};
+
+static struct rtld_lock lock_place[MAX_RTLD_LOCKS] __aligned(CACHE_LINE_SIZE);
+static int busy_places;
+
+static void *
+_thr_rtld_lock_create(void)
+{
+	int locki;
+	struct rtld_lock *l;
+	static const char fail[] = "_thr_rtld_lock_create failed\n";
+
+	for (locki = 0; locki < MAX_RTLD_LOCKS; locki++) {
+		if ((busy_places & (1 << locki)) == 0)
+			break;
+	}
+	if (locki == MAX_RTLD_LOCKS) {
+		write(2, fail, sizeof(fail) - 1);
+		return (NULL);
+	}
+	busy_places |= (1 << locki);
+
+	l = &lock_place[locki];
+	l->lock.rw_flags = URWLOCK_PREFER_READER;
+	return (l);
+}
+
+static void
+_thr_rtld_lock_destroy(void *lock)
+{
+	int locki;
+	size_t i;
+
+	locki = (struct rtld_lock *)lock - &lock_place[0];
+	for (i = 0; i < sizeof(struct rtld_lock); ++i)
+		((char *)lock)[i] = 0;
+	busy_places &= ~(1 << locki);
+}
+
+#define SAVE_ERRNO()	{			\
+	if (curthread != _thr_initial)		\
+		errsave = curthread->error;	\
+	else					\
+		errsave = __libsys_errno;	\
+}
+
+#define RESTORE_ERRNO()	{ 			\
+	if (curthread != _thr_initial)  	\
+		curthread->error = errsave;	\
+	else					\
+		__libsys_errno = errsave;	\
+}
+
+static void
+_thr_rtld_rlock_acquire(void *lock)
+{
+	struct pthread		*curthread;
+	struct rtld_lock	*l;
+	int			errsave;
+
+	curthread = _get_curthread();
+	SAVE_ERRNO();
+	l = (struct rtld_lock *)lock;
+
+	if (l->wowner == curthread) {
+		l->rlocks++;
+	} else {
+		THR_CRITICAL_ENTER(curthread);
+		while (_thr_rwlock_rdlock(&l->lock, 0, NULL) != 0)
+			;
+	}
+	curthread->rdlock_count++;
+	RESTORE_ERRNO();
+}
+
+static void
+_thr_rtld_wlock_acquire(void *lock)
+{
+	struct pthread		*curthread;
+	struct rtld_lock	*l;
+	int			errsave;
+
+	curthread = _get_curthread();
+	SAVE_ERRNO();
+	l = (struct rtld_lock *)lock;
+
+	THR_CRITICAL_ENTER(curthread);
+	while (_thr_rwlock_wrlock(&l->lock, NULL) != 0)
+		;
+	l->wowner = curthread;
+	RESTORE_ERRNO();
+}
+
+static void
+_thr_rtld_lock_release(void *lock)
+{
+	struct pthread		*curthread;
+	struct rtld_lock	*l;
+	int32_t			state;
+	int			errsave;
+
+	curthread = _get_curthread();
+	SAVE_ERRNO();
+	l = (struct rtld_lock *)lock;
+	
+	state = l->lock.rw_state;
+	if (__predict_false(_thr_after_fork)) {
+		/*
+		 * After fork, only this thread is running, there is no
+		 * waiters.  Keeping waiters recorded in rwlock breaks
+		 * wake logic.
+		 */
+		atomic_clear_int(&l->lock.rw_state,
+		    URWLOCK_WRITE_WAITERS | URWLOCK_READ_WAITERS);
+		l->lock.rw_blocked_readers = 0;
+		l->lock.rw_blocked_writers = 0;
+	}
+	if ((state & URWLOCK_WRITE_OWNER) != 0) {
+		if (l->rlocks > 0) {
+			l->rlocks--;
+			return;
+		} else {
+			l->wowner = NULL;
+		}
+	}
+	if (_thr_rwlock_unlock(&l->lock) == 0) {
+		if ((state & URWLOCK_WRITE_OWNER) == 0)
+			curthread->rdlock_count--;
+		THR_CRITICAL_LEAVE(curthread);
+	}
+	RESTORE_ERRNO();
+}
+
+static int
+_thr_rtld_set_flag(int mask __unused)
+{
+	/*
+	 * The caller's code in rtld-elf is broken, it is not signal safe,
+	 * just return zero to fool it.
+	 */
+	return (0);
+}
+
+static int
+_thr_rtld_clr_flag(int mask __unused)
+{
+	return (0);
+}
+
+/*
+ * ABI bug workaround: This symbol must be present for rtld to accept
+ * RTLI_VERSION from RtldLockInfo
+ */
+extern char _pli_rtli_version;
+char _pli_rtli_version;
+
+static char *
+_thr_dlerror_loc(void)
+{
+	struct pthread *curthread;
+
+	curthread = _get_curthread();
+	return (curthread->dlerror_msg);
+}
+
+static int *
+_thr_dlerror_seen(void)
+{
+	struct pthread *curthread;
+
+	curthread = _get_curthread();
+	return (&curthread->dlerror_seen);
+}
+
+void
+_thr_rtld_init(void)
+{
+	struct RtldLockInfo	li;
+	struct pthread		*curthread;
+	ucontext_t *uc;
+	int uc_len;
+	char dummy[2] = {};
+
+	curthread = _get_curthread();
+
+	/* force to resolve _umtx_op PLT */
+	_umtx_op_err(&dummy, UMTX_OP_WAKE, 1, 0, 0);
+	
+	/* force to resolve errno() PLT */
+	__error();
+
+	/* force to resolve memcpy PLT */
+	memcpy(&dummy[0], &dummy[1], 1);
+
+	mprotect(NULL, 0, 0);
+	_rtld_get_stack_prot();
+	thr_wake(-1);
+
+	li.rtli_version = RTLI_VERSION;
+	li.lock_create  = _thr_rtld_lock_create;
+	li.lock_destroy = _thr_rtld_lock_destroy;
+	li.rlock_acquire = _thr_rtld_rlock_acquire;
+	li.wlock_acquire = _thr_rtld_wlock_acquire;
+	li.lock_release  = _thr_rtld_lock_release;
+	li.thread_set_flag = _thr_rtld_set_flag;
+	li.thread_clr_flag = _thr_rtld_clr_flag;
+	li.at_fork = NULL;
+	li.dlerror_loc = _thr_dlerror_loc;
+	li.dlerror_loc_sz = sizeof(curthread->dlerror_msg);
+	li.dlerror_seen = _thr_dlerror_seen;
+
+	/*
+	 * Preresolve the symbols needed for the fork interposer.  We
+	 * call _rtld_atfork_pre() and _rtld_atfork_post() with NULL
+	 * argument to indicate that no actual locking inside the
+	 * functions should happen.  Neither rtld compat locks nor
+	 * libthr rtld locks cannot work there:
+	 * - compat locks do not handle the case of two locks taken
+	 *   in write mode (the signal mask for the thread is corrupted);
+	 * - libthr locks would work, but locked rtld_bind_lock prevents
+	 *   symbol resolution for _rtld_atfork_post.
+	 */
+	_rtld_atfork_pre(NULL);
+	_rtld_atfork_post(NULL);
+	_malloc_prefork();
+	_malloc_postfork();
+	getpid();
+	syscall(SYS_getpid);
+
+	/* mask signals, also force to resolve __sys_sigprocmask PLT */
+	_thr_signal_block(curthread);
+	_rtld_thread_init(&li);
+	_thr_signal_unblock(curthread);
+	_thr_signal_block_check_fast();
+	_thr_signal_block_setup(curthread);
+
+	/* resolve machine depended functions, if any */
+	_thr_resolve_machdep();
+
+	uc_len = __getcontextx_size();
+	uc = alloca(uc_len);
+	getcontext(uc);
+	__fillcontextx2((char *)uc);
+}