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 /* Copyright (c) 1988 AT&T */
28 /* All Rights Reserved */
29
30 #pragma ident "%Z%%M% %I% %E% SMI"
31
32 #pragma weak _makecontext = makecontext
33
34 #include "lint.h"
35 #include <stdarg.h>
36 #include <ucontext.h>
37 #include <sys/stack.h>
38
39 /*
40 * The ucontext_t that the user passes in must have been primed with a
41 * call to getcontext(2), have the uc_stack member set to reflect the
42 * stack which this context will use, and have the uc_link member set
43 * to the context which should be resumed when this context returns.
44 * When makecontext() returns, the ucontext_t will be set to run the
45 * given function with the given parameters on the stack specified by
46 * uc_stack, and which will return to the ucontext_t specified by uc_link.
47 */
48
49 static void resumecontext(void);
50
51 void
makecontext(ucontext_t * ucp,void (* func)(),int argc,...)52 makecontext(ucontext_t *ucp, void (*func)(), int argc, ...)
53 {
54 long *sp;
55 long *tsp;
56 va_list ap;
57 size_t size;
58 int pusharg = (argc > 6 ? argc - 6 : 0);
59 greg_t tmp;
60 int i;
61
62 ucp->uc_mcontext.gregs[REG_PC] = (greg_t)func;
63
64 size = sizeof (long) * (pusharg + 1);
65
66 /*
67 * Calculate new value for %rsp. On entry to a function,
68 * %rsp must be STACK_ENTRY_ALIGNed but not STACK_ALIGNed.
69 * This is because the pushq %rbp will correct the alignment.
70 */
71
72 sp = (long *)(((uintptr_t)ucp->uc_stack.ss_sp +
73 ucp->uc_stack.ss_size - size) & ~(STACK_ENTRY_ALIGN - 1));
74
75 if (((uintptr_t)sp & (STACK_ALIGN - 1ul)) == 0)
76 sp -= STACK_ENTRY_ALIGN / sizeof (*sp);
77
78 tsp = sp + 1;
79
80 va_start(ap, argc);
81
82 for (i = 0; i < argc; i++) {
83 tmp = va_arg(ap, long);
84 switch (i) {
85 case 0:
86 ucp->uc_mcontext.gregs[REG_RDI] = tmp;
87 break;
88 case 1:
89 ucp->uc_mcontext.gregs[REG_RSI] = tmp;
90 break;
91 case 2:
92 ucp->uc_mcontext.gregs[REG_RDX] = tmp;
93 break;
94 case 3:
95 ucp->uc_mcontext.gregs[REG_RCX] = tmp;
96 break;
97 case 4:
98 ucp->uc_mcontext.gregs[REG_R8] = tmp;
99 break;
100 case 5:
101 ucp->uc_mcontext.gregs[REG_R9] = tmp;
102 break;
103 default:
104 *tsp++ = tmp;
105 break;
106 }
107 }
108
109 va_end(ap);
110
111 *sp = (long)resumecontext; /* return address */
112
113 ucp->uc_mcontext.gregs[REG_SP] = (greg_t)sp;
114 }
115
116
117 static void
resumecontext(void)118 resumecontext(void)
119 {
120 ucontext_t uc;
121
122 (void) getcontext(&uc);
123 (void) setcontext(uc.uc_link);
124 }
125