2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2004 Suleiman Souhlal
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #include <sys/param.h>
40 __weak_reference(__makecontext, makecontext);
42 void _ctx_done(ucontext_t *ucp);
43 void _ctx_start(void);
46 _ctx_done(ucontext_t *ucp)
48 if (ucp->uc_link == NULL)
51 /* invalidate context */
52 ucp->uc_mcontext.mc_len = 0;
54 setcontext((const ucontext_t *)ucp->uc_link);
56 abort(); /* should never return from above call */
61 __makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...)
66 int i, regargs, stackargs;
69 if ((ucp == NULL) || (argc < 0) || (argc > NCARGS)
70 || (ucp->uc_stack.ss_sp == NULL)
71 || (ucp->uc_stack.ss_size < MINSIGSTKSZ)) {
72 /* invalidate context */
73 ucp->uc_mcontext.mc_len = 0;
78 * The stack must have space for the frame pointer, saved
79 * link register, overflow arguments, and be 16-byte
82 stackargs = (argc > 8) ? argc - 8 : 0;
83 sp = (char *) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size
84 - sizeof(uint32_t)*(stackargs + 2);
85 sp = (char *)((uint32_t)sp & ~0x1f);
87 mc = &ucp->uc_mcontext;
90 * Up to 8 register args. Assumes all args are 32-bit and
91 * integer only. Not sure how to cater for floating point,
92 * although 64-bit args will work if aligned correctly
95 regargs = (argc > 8) ? 8 : argc;
97 for (i = 0; i < regargs; i++)
98 mc->mc_gpr[3 + i] = va_arg(ap, uint32_t);
101 * Overflow args go onto the stack
106 /* Skip past frame pointer and saved LR */
107 argp = (uint32_t *)sp + 2;
109 for (i = 0; i < stackargs; i++)
110 *argp++ = va_arg(ap, uint32_t);
115 * Use caller-saved regs 14/15 to hold params that _ctx_start
116 * will use to invoke the user-supplied func
118 mc->mc_srr0 = (uint32_t) _ctx_start;
119 mc->mc_gpr[1] = (uint32_t) sp; /* new stack pointer */
120 mc->mc_gpr[14] = (uint32_t) start; /* r14 <- start */
121 mc->mc_gpr[15] = (uint32_t) ucp; /* r15 <- ucp */