makecontext.c revision 115657 
1/*
2 * Copyright (c) 2003 Marcel Moolenaar
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/lib/libc/ia64/gen/makecontext.c 115657 2003-06-02 00:16:39Z marcel $");
29
30#include <sys/types.h>
31#include <sys/ucontext.h>
32#include <machine/fpu.h>
33#include <stdarg.h>
34#include <stdio.h>
35
36struct fdesc {
37	uint64_t ip;
38	uint64_t gp;
39};
40
41typedef void (*func_t)(uint64_t, uint64_t, uint64_t, uint64_t, uint64_t,
42    uint64_t, uint64_t, uint64_t);
43
44static __inline uint64_t *
45spill(uint64_t *bsp, uint64_t arg)
46{
47	*bsp++ = arg;
48	if (((intptr_t)bsp & 0x1ff) == 0x1f8)
49		*bsp++ = 0;
50	return (bsp);
51}
52
53static void
54ctx_wrapper(ucontext_t *ucp, func_t func, uint64_t *args)
55{
56
57	(*func)(args[0], args[1], args[2], args[3], args[4], args[5], args[6],
58	    args[7]);
59	if (ucp->uc_link == NULL)
60		exit(0);
61	setcontext((const ucontext_t *)ucp->uc_link);
62	/* should never get here */
63	abort();
64	/* NOTREACHED */
65}
66
67__weak_reference(__makecontext, makecontext);
68
69void
70__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
71{
72	uint64_t *args, *bsp;
73	va_list ap;
74	int i;
75
76	/*
77	 * Drop the ball completely if something's not right. We only
78	 * support general registers as arguments and not more than 8
79	 * of them. Things get hairy if we need to support FP registers
80	 * (alignment issues) or more than 8 arguments (stack based).
81	 */
82	if (argc < 0 || argc > 8 || ucp == NULL ||
83	    ucp->uc_stack.ss_sp == NULL || (ucp->uc_stack.ss_size & 15) ||
84	    ((intptr_t)ucp->uc_stack.ss_sp & 15) ||
85	    ucp->uc_stack.ss_size < MINSIGSTKSZ)
86		abort();
87
88	/*
89	 * Copy the arguments of function 'func' onto the (memory) stack.
90	 * Always take up space for 8 arguments.
91	 */
92	va_start(ap, argc);
93	args = (uint64_t*)(ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) - 8;
94	i = 0;
95	while (i < argc)
96		args[i++] = va_arg(ap, uint64_t);
97	while (i < 8)
98		args[i++] = 0;
99	va_end(ap);
100
101	/*
102	 * Push (spill) the arguments of the context wrapper onto the register
103	 * stack. They get loaded by the RSE on a context switch.
104	 */
105	bsp = (uint64_t*)ucp->uc_stack.ss_sp;
106	bsp = spill(bsp, (intptr_t)ucp);
107	bsp = spill(bsp, (intptr_t)func);
108	bsp = spill(bsp, (intptr_t)args);
109
110	/*
111	 * Setup the MD portion of the context.
112	 */
113	memset(&ucp->uc_mcontext, 0, sizeof(ucp->uc_mcontext));
114	ucp->uc_mcontext.mc_special.sp = (intptr_t)args - 16;
115	ucp->uc_mcontext.mc_special.bspstore = (intptr_t)bsp;
116	ucp->uc_mcontext.mc_special.pfs = (3 << 7) | 3;
117	ucp->uc_mcontext.mc_special.rsc = 0xf;
118	ucp->uc_mcontext.mc_special.rp = ((struct fdesc*)ctx_wrapper)->ip;
119	ucp->uc_mcontext.mc_special.gp = ((struct fdesc*)ctx_wrapper)->gp;
120	ucp->uc_mcontext.mc_special.fpsr = IA64_FPSR_DEFAULT;
121}
122