2 * Copyright (c) 2004 Suleiman Souhlal
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
30 #include <sys/param.h>
38 __weak_reference(__makecontext, makecontext);
40 void _ctx_done(ucontext_t *ucp);
41 void _ctx_start(void);
44 _ctx_done(ucontext_t *ucp)
46 if (ucp->uc_link == NULL)
49 /* invalidate context */
50 ucp->uc_mcontext.mc_len = 0;
52 setcontext((const ucontext_t *)ucp->uc_link);
54 abort(); /* should never return from above call */
59 __makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...)
64 int i, regargs, stackargs;
67 if ((ucp == NULL) || (argc < 0) || (argc > NCARGS)
68 || (ucp->uc_stack.ss_sp == NULL)
69 || (ucp->uc_stack.ss_size < MINSIGSTKSZ)) {
70 /* invalidate context */
71 ucp->uc_mcontext.mc_len = 0;
76 * The stack must have space for the frame pointer, saved
77 * link register, overflow arguments, and be 16-byte
80 stackargs = (argc > 8) ? argc - 8 : 0;
81 sp = (char *) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size
82 - sizeof(uintptr_t)*(stackargs + 2);
83 sp = (char *)((uintptr_t)sp & ~0x1f);
85 mc = &ucp->uc_mcontext;
88 * Up to 8 register args. Assumes all args are 64-bit and
89 * integer only. Not sure how to cater for floating point.
91 regargs = (argc > 8) ? 8 : argc;
93 for (i = 0; i < regargs; i++)
94 mc->mc_gpr[3 + i] = va_arg(ap, uint64_t);
97 * Overflow args go onto the stack
102 /* Skip past frame pointer and saved LR */
103 argp = (uint64_t *)sp + 6;
105 for (i = 0; i < stackargs; i++)
106 *argp++ = va_arg(ap, uint64_t);
111 * Use caller-saved regs 14/15 to hold params that _ctx_start
112 * will use to invoke the user-supplied func
114 mc->mc_srr0 = (uintptr_t) _ctx_start;
115 mc->mc_gpr[1] = (uintptr_t) sp; /* new stack pointer */
116 mc->mc_gpr[14] = (uintptr_t) start; /* r14 <- start */
117 mc->mc_gpr[15] = (uintptr_t) ucp; /* r15 <- ucp */