xref: /titanic_44/usr/src/cmd/mdb/common/kmdb/kmdb_context.c (revision fb3fb4f3d76d55b64440afd0af72775dfad3bd1d)
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  * Copyright 2004 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 /*
30  * Debugger co-routine context support.  kmdb co-routines are essentially the
31  * same as the ones used by mdb, with the exception that we allocate the stack
32  * for the co-routine from our heap.
33  */
34 
35 #include <kmdb/kmdb_context_impl.h>
36 #include <mdb/mdb_modapi.h>
37 #include <mdb/mdb_debug.h>
38 #include <mdb/mdb_err.h>
39 #include <mdb/mdb_umem.h>
40 #include <mdb/mdb.h>
41 
42 #include <sys/types.h>
43 
44 #include <ucontext.h>
45 #include <setjmp.h>
46 
47 static void
48 context_init(mdb_context_t *volatile c)
49 {
50 	c->ctx_status = c->ctx_func();
51 	ASSERT(c->ctx_resumes > 0);
52 	longjmp(c->ctx_pcb, 1);
53 }
54 
55 mdb_context_t *
56 mdb_context_create(int (*func)(void))
57 {
58 	mdb_context_t *c = mdb_zalloc(sizeof (mdb_context_t), UM_NOSLEEP);
59 	size_t pagesize = mdb.m_pagesize;
60 
61 	if (c == NULL)
62 		return (NULL);
63 
64 	c->ctx_func = func;
65 	c->ctx_stacksize = pagesize * 4;
66 	c->ctx_stack = mdb_alloc_align(c->ctx_stacksize, pagesize, UM_NOSLEEP);
67 
68 	if (c->ctx_stack == NULL) {
69 		mdb_free(c, sizeof (mdb_context_t));
70 		return (NULL);
71 	}
72 
73 	kmdb_makecontext(&c->ctx_uc, (void (*)(void *))context_init, c,
74 	    c->ctx_stack, c->ctx_stacksize);
75 
76 	return (c);
77 }
78 
79 void
80 mdb_context_destroy(mdb_context_t *c)
81 {
82 	mdb_free_align(c->ctx_stack, c->ctx_stacksize);
83 	mdb_free(c, sizeof (mdb_context_t));
84 }
85 
86 void
87 mdb_context_switch(mdb_context_t *c)
88 {
89 	if (setjmp(c->ctx_pcb) == 0 && kmdb_setcontext(&c->ctx_uc) == -1)
90 		fail("failed to change context to %p", (void *)c);
91 	else
92 		fail("unexpectedly returned from context %p", (void *)c);
93 }
94 
95 jmp_buf *
96 mdb_context_getpcb(mdb_context_t *c)
97 {
98 	c->ctx_resumes++;
99 	return (&c->ctx_pcb);
100 }
101