1 /* Create new context. OpenRISC version.
2 Copyright (C) 2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <sysdep.h>
20 #include <stdarg.h>
21 #include <stdint.h>
22 #include <ucontext.h>
23
24 /* makecontext sets up a stack and the registers for the
25 user context. The stack looks like this:
26
27 +-----------------------+
28 | padding as required |
29 +-----------------------+
30 sp -> | parameters 7 to n |
31 +-----------------------+
32
33 The registers are set up like this:
34 r3-r8 : parameters 1 to 6
35 r14 : uc_link
36 r1 : stack pointer
37 r2 : frame pointer, set to NULL
38 */
39 void
__makecontext(ucontext_t * ucp,void (* func)(void),int argc,...)40 __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
41 {
42 extern void __startcontext (void);
43 unsigned long int *sp;
44 va_list ap;
45 int i;
46
47 sp = (unsigned long int *)
48 ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
49
50 /* Allocate stack arguments. */
51 sp -= argc < 6 ? 0 : argc - 6;
52
53 /* Keep the stack aligned. */
54 sp = (unsigned long int *) (((uintptr_t) sp) & -4L);
55
56 /* Keep uc_link in r14. */
57 ucp->uc_mcontext.__gprs[14] = (uintptr_t) ucp->uc_link;
58 /* Return address points to function __startcontext. */
59 ucp->uc_mcontext.__gprs[9] = (uintptr_t) &__startcontext;
60 /* Frame pointer is null. */
61 ucp->uc_mcontext.__gprs[2] = (uintptr_t) 0;
62 /* Restart in user-space starting at 'func'. */
63 ucp->uc_mcontext.__gprs[11] = (uintptr_t) func;
64 /* Set stack pointer. */
65 ucp->uc_mcontext.__gprs[1] = (uintptr_t) sp;
66
67 va_start (ap, argc);
68 for (i = 0; i < argc; ++i)
69 if (i < 6)
70 ucp->uc_mcontext.__gprs[i + 3] = va_arg (ap, unsigned long int);
71 else
72 sp[i - 6] = va_arg (ap, unsigned long int);
73
74 va_end (ap);
75 }
76
77 weak_alias (__makecontext, makecontext)
78