unwind.c revision 1219:f89f56c2d9ac 
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22
23/*
24 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
25 * Use is subject to license terms.
26 */
27
28#pragma ident	"%Z%%M%	%I%	%E% SMI"
29
30#include "synonyms.h"
31#include "thr_uberdata.h"
32#include <dlfcn.h>
33
34/*
35 * This is common code for sparc, sparcv9, and i386.
36 * The amd64 unwind code is vastly different from this.
37 * Look under the amd64-specific directory structure for details.
38 */
39
40/*
41 * _ex_unwind() is provided by libC, but if libC is not loaded we
42 * need to call a local version of _ex_unwind() which does exactly
43 * the same thing except for calling C++ destructors.
44 */
45extern	void	_ex_clnup_handler(void *, void (*)(void *));
46extern	void	_ex_unwind_local(void);
47#pragma unknown_control_flow(_ex_clnup_handler)
48#pragma unknown_control_flow(_ex_unwind_local)
49
50/*
51 * _t_cancel(fp):calls cleanup handlers if there are any in
52 *		 frame (fp), and calls _ex_unwind() to call
53 *		 destructors if libC has been linked.
54 *
55 * Control comes here from _thrp_unwind.  Logically:
56 *
57 *	_thrp_unwind: first arg = current fp;
58 *	    jump _t_cancel;
59 *
60 * We could have called _t_cancel(_getfp) from _thr_exit()
61 * but _ex_unwind() also calls _t_cancel() and it does after
62 * poping out the two frames.  If _ex_unwind() passes the current
63 * fp, then it will be invalid.  For a caller of _thrp_unwind()
64 * it looks as if it is calling _t_cancel(fp).
65 *
66 * _t_cancel will eventually call _thrp_exit().
67 * It never returns from _t_cancel().
68 *
69 */
70void
71_t_cancel(void *fp)
72{
73	ulwp_t *self = curthread;
74	__cleanup_t *head;
75	void (*fptr)(void (*func)(void *), void *arg);
76
77	/* Do this once per thread exit, not once per unwind frame */
78	if (self->ul_ex_unwind == NULL &&
79	    (self->ul_ex_unwind = dlsym(RTLD_PROBE, "_ex_unwind")) == NULL)
80		self->ul_ex_unwind = (void *)-1;
81
82	if (self->ul_ex_unwind == (void *)-1)
83		fptr = NULL;
84	else
85		fptr = (void (*)())self->ul_ex_unwind;
86
87	if (fp == NULL) {
88		_thrp_exit();
89		thr_panic("_t_cancel(): _thrp_exit() returned");
90	}
91
92	if ((head = self->ul_clnup_hdr) != NULL && fp == head->fp) {
93		self->ul_clnup_hdr = head->next;
94		/* execute the cleanup handler */
95		_ex_clnup_handler(head->arg, head->func);
96		thr_panic("_t_cancel(): _ex_clnup_handler() returned");
97	}
98
99	if (fptr != NULL && self->ul_unwind) {
100		/* libC is loaded and thread is canceled, call libC version */
101		(*fptr)(_thrp_unwind, NULL);
102		thr_panic("_t_cancel(): _ex_unwind() returned");
103	} else if (head != NULL) {
104		/* libC not present, call local version */
105		_ex_unwind_local();
106		thr_panic("_t_cancel(): _ex_unwind_local() returned");
107	} else {
108		/* libC not present and no cleanup handlers, exit here */
109		_thrp_exit();
110		thr_panic("_t_cancel(): _thrp_exit() returned");
111	}
112	/* never returns here */
113}
114