xref: /freebsd/lib/libc/powerpc64/gen/_ctx_start.S (revision 24e4dcf4ba5e9dedcf89efd358ea3e1fe5867020)
1/*
2 * Copyright (c) 2004 Suleiman Souhlal
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 * 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.
13 *
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
24 * SUCH DAMAGE.
25 */
26
27 #include <machine/asm.h>
28	.globl  CNAME(_ctx_done)
29	.globl  CNAME(abort)
30
31 ENTRY(_ctx_start)
32#if !defined(_CALL_ELF) || _CALL_ELF == 1
33	/* Load values from function descriptor */
34	ld	%r2,8(%r14)
35	ld	%r14,0(%r14)
36#else
37	/*
38	 * The stack frame was already set up in makecontext(),
39	 * so we can safely use the guaranteed fields here.
40	 *
41	 * Note we do step on the allocated stack frame's TOC,
42	 * but since we never return from this function (i.e.
43	 * never restore the stack frame) this should be safe.
44	 */
45	std	%r2,24(%r1)	/* save TOC */
46
47	/* Load global entry point */
48	mr	%r12,%r14
49#endif
50	mtlr	%r14
51	blrl			/* branch to start function */
52	mr	%r3,%r15	/* pass pointer to ucontext as argument */
53	nop
54#if defined(_CALL_ELF) && _CALL_ELF != 1
55	/* Restore TOC */
56	ld	%r2,24(%r1)
57#endif
58	bl	CNAME(_ctx_done) /* branch to ctxt completion func */
59	/*
60	 * we should never return from the
61	 * above branch.
62	 */
63	nop
64	bl	CNAME(abort)	/* abort */
65	nop
66 END(_ctx_start)
67
68	.section .note.GNU-stack,"",%progbits
69