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 (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29#include "lint.h"
30#include "thr_uberdata.h"
31#include <dlfcn.h>
32
33/*
34 * This is common code for sparc, sparcv9, and i386.
35 * The amd64 unwind code is vastly different from this.
36 * Look under the amd64-specific directory structure for details.
37 */
38
39/*
40 * _ex_unwind() is provided by libC, but if libC is not loaded we
41 * need to call a local version of _ex_unwind() which does exactly
42 * the same thing except for calling C++ destructors.
43 */
44extern	void	_ex_clnup_handler(void *, void (*)(void *));
45extern	void	_ex_unwind_local(void);
46#pragma unknown_control_flow(_ex_clnup_handler)
47#pragma unknown_control_flow(_ex_unwind_local)
48
49/*
50 * _t_cancel(fp):calls cleanup handlers if there are any in
51 *		 frame (fp), and calls _ex_unwind() to call
52 *		 destructors if libC has been linked.
53 *
54 * Control comes here from _thrp_unwind.  Logically:
55 *
56 *	_thrp_unwind: first arg = current fp;
57 *	    jump _t_cancel;
58 *
59 * We could have called _t_cancel(_getfp) from thr_exit()
60 * but _ex_unwind() also calls _t_cancel() and it does after
61 * poping out the two frames.  If _ex_unwind() passes the current
62 * fp, then it will be invalid.  For a caller of _thrp_unwind()
63 * it looks as if it is calling _t_cancel(fp).
64 *
65 * _t_cancel will eventually call _thrp_exit().
66 * It never returns from _t_cancel().
67 *
68 */
69void
70_t_cancel(void *fp)
71{
72	ulwp_t *self = curthread;
73	__cleanup_t *head;
74	void (*fptr)(void (*func)(void *), void *arg);
75
76	/* Do this once per thread exit, not once per unwind frame */
77	if (self->ul_ex_unwind == NULL &&
78	    (self->ul_ex_unwind = dlsym(RTLD_PROBE, "_ex_unwind")) == NULL)
79		self->ul_ex_unwind = (void *)-1;
80
81	if (self->ul_ex_unwind == (void *)-1)
82		fptr = NULL;
83	else
84		fptr = (void (*)())self->ul_ex_unwind;
85
86	if (fp == NULL) {
87		_thrp_exit();
88		thr_panic("_t_cancel(): _thrp_exit() returned");
89	}
90
91	if ((head = self->ul_clnup_hdr) != NULL && fp == head->fp) {
92		self->ul_clnup_hdr = head->next;
93		/* execute the cleanup handler */
94		_ex_clnup_handler(head->arg, head->func);
95		thr_panic("_t_cancel(): _ex_clnup_handler() returned");
96	}
97
98	if (fptr != NULL && self->ul_unwind) {
99		/* libC is loaded and thread is canceled, call libC version */
100		(*fptr)(_thrp_unwind, NULL);
101		thr_panic("_t_cancel(): _ex_unwind() returned");
102	} else if (head != NULL) {
103		/* libC not present, call local version */
104		_ex_unwind_local();
105		thr_panic("_t_cancel(): _ex_unwind_local() returned");
106	} else {
107		/* libC not present and no cleanup handlers, exit here */
108		_thrp_exit();
109		thr_panic("_t_cancel(): _thrp_exit() returned");
110	}
111	/* never returns here */
112}
113