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 #pragma weak ___makecontext_v2 = __makecontext_v2
34
35 #include "lint.h"
36 #include <stdarg.h>
37 #include <strings.h>
38 #include <sys/ucontext.h>
39 #include <sys/stack.h>
40 #include <sys/frame.h>
41
42 /*
43 * The ucontext_t that the user passes in must have been primed with a
44 * call to getcontext(2), have the uc_stack member set to reflect the
45 * stack which this context will use, and have the uc_link member set
46 * to the context which should be resumed when this context returns.
47 * When makecontext() returns, the ucontext_t will be set to run the
48 * given function with the given parameters on the stack specified by
49 * uc_stack, and which will return to the ucontext_t specified by uc_link.
50 */
51
52 static void resumecontext(void);
53
54 void
makecontext(ucontext_t * ucp,void (* func)(),int argc,...)55 makecontext(ucontext_t *ucp, void (*func)(), int argc, ...)
56 {
57 greg_t *reg;
58 long *tsp;
59 char *sp;
60 int argno;
61 va_list ap;
62 size_t size;
63
64 reg = ucp->uc_mcontext.gregs;
65 reg[REG_PC] = (greg_t)func;
66 reg[REG_nPC] = reg[REG_PC] + 0x4;
67
68 /*
69 * Reserve enough space for a frame and the arguments beyond the
70 * sixth; round to stack alignment.
71 */
72 size = sizeof (struct frame);
73 size += (argc > 6 ? argc - 6 : 0) * sizeof (long);
74
75 /*
76 * The legacy implemenation of makecontext() on sparc has been to
77 * interpret the uc_stack.ss_sp member incorrectly as the top of the
78 * stack rather than the base. We preserve this behavior here, but
79 * provide the correct semantics in __makecontext_v2().
80 */
81 sp = (char *)(((uintptr_t)ucp->uc_stack.ss_sp - size) &
82 ~(STACK_ALIGN - 1));
83
84 /*
85 * Copy all args to the stack, and put the first 6 args into the
86 * ucontext_t. Zero the other fields of the frame.
87 */
88 /* LINTED pointer cast may result in improper alignment */
89 tsp = &((struct frame *)sp)->fr_argd[0];
90 bzero(sp, sizeof (struct frame));
91
92 va_start(ap, argc);
93
94 for (argno = 0; argno < argc; argno++) {
95 if (argno < 6)
96 *tsp++ = reg[REG_O0 + argno] = va_arg(ap, long);
97 else
98 *tsp++ = va_arg(ap, long);
99 }
100
101 va_end(ap);
102
103 reg[REG_SP] = (greg_t)sp - STACK_BIAS; /* sp (when done) */
104 reg[REG_O7] = (greg_t)resumecontext - 8; /* return pc */
105 }
106
107 void
__makecontext_v2(ucontext_t * ucp,void (* func)(),int argc,...)108 __makecontext_v2(ucontext_t *ucp, void (*func)(), int argc, ...)
109 {
110 greg_t *reg;
111 long *tsp;
112 char *sp;
113 int argno;
114 va_list ap;
115 size_t size;
116
117 reg = ucp->uc_mcontext.gregs;
118 reg[REG_PC] = (greg_t)func;
119 reg[REG_nPC] = reg[REG_PC] + 0x4;
120
121 /*
122 * Reserve enough space for a frame and the arguments beyond the
123 * sixth; round to stack alignment.
124 */
125 size = sizeof (struct frame);
126 size += (argc > 6 ? argc - 6 : 0) * sizeof (long);
127
128 sp = (char *)(((uintptr_t)ucp->uc_stack.ss_sp +
129 ucp->uc_stack.ss_size - size) & ~(STACK_ALIGN - 1));
130
131 /*
132 * Copy all args to the stack, and put the first 6 args into the
133 * ucontext_t. Zero the other fields of the frame.
134 */
135 /* LINTED pointer cast may result in improper alignment */
136 tsp = &((struct frame *)sp)->fr_argd[0];
137 bzero(sp, sizeof (struct frame));
138
139 va_start(ap, argc);
140
141 for (argno = 0; argno < argc; argno++) {
142 if (argno < 6)
143 *tsp++ = reg[REG_O0 + argno] = va_arg(ap, long);
144 else
145 *tsp++ = va_arg(ap, long);
146 }
147
148 va_end(ap);
149
150 reg[REG_SP] = (greg_t)sp - STACK_BIAS; /* sp (when done) */
151 reg[REG_O7] = (greg_t)resumecontext - 8; /* return pc */
152 }
153
154 static void
resumecontext(void)155 resumecontext(void)
156 {
157 /*
158 * We can't include ucontext.h (where these functions are defined)
159 * because it remaps the symbol makecontext.
160 */
161 extern int getcontext(ucontext_t *);
162 extern int setcontext(const ucontext_t *);
163 ucontext_t uc;
164
165 (void) getcontext(&uc);
166 (void) setcontext(uc.uc_link);
167 }
168