xref: /freebsd/lib/libc/riscv/gen/makecontext.c (revision 4543ef516683042d46f3bd3bb8a4f3f746e00499)
1 /*-
2  * Copyright (c) 2015 Ruslan Bukin <br@bsdpad.com>
3  * All rights reserved.
4  *
5  * Portions of this software were developed by SRI International and the
6  * University of Cambridge Computer Laboratory under DARPA/AFRL contract
7  * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
8  *
9  * Portions of this software were developed by the University of Cambridge
10  * Computer Laboratory as part of the CTSRD Project, with support from the
11  * UK Higher Education Innovation Fund (HEIF).
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #include <sys/param.h>
36 
37 #include <machine/riscvreg.h>
38 
39 #include <inttypes.h>
40 #include <stdarg.h>
41 #include <stdlib.h>
42 #include <ucontext.h>
43 
44 void _ctx_start(void);
45 
46 void
47 ctx_done(ucontext_t *ucp)
48 {
49 
50 	if (ucp->uc_link == NULL) {
51 		exit(0);
52 	} else {
53 		setcontext((const ucontext_t *)ucp->uc_link);
54 		abort();
55 	}
56 }
57 
58 __weak_reference(__makecontext, makecontext);
59 
60 void
61 __makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
62 {
63 	struct gpregs *gp;
64 	va_list ap;
65 	int i;
66 
67 	/* A valid context is required. */
68 	if (ucp == NULL)
69 		return;
70 
71 	if ((argc < 0) || (argc > 8))
72 		return;
73 
74 	gp = &ucp->uc_mcontext.mc_gpregs;
75 
76 	va_start(ap, argc);
77 	/* Pass up to eight arguments in a0-7. */
78 	for (i = 0; i < argc && i < 8; i++)
79 		gp->gp_a[i] = va_arg(ap, uint64_t);
80 	va_end(ap);
81 
82 	/* Set the stack */
83 	gp->gp_sp = STACKALIGN(ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
84 	/* Arrange for return via the trampoline code. */
85 	gp->gp_sepc = (__register_t)_ctx_start;
86 	gp->gp_s[0] = (__register_t)func;
87 	gp->gp_s[1] = (__register_t)ucp;
88 }
89