1 | /* Copyright (C) 2012-2022 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <stdarg.h> |
19 | #include <ucontext.h> |
20 | |
21 | /* Number of arguments that go in registers. */ |
22 | #define NREG_ARGS 4 |
23 | |
24 | /* Take a context previously prepared via getcontext() and set to |
25 | call func() with the given int only args. */ |
26 | void |
27 | __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...) |
28 | { |
29 | extern void __startcontext (void); |
30 | unsigned long *funcstack; |
31 | va_list vl; |
32 | unsigned long *regptr; |
33 | unsigned int reg; |
34 | int misaligned; |
35 | |
36 | /* Start at the top of stack. */ |
37 | funcstack = (unsigned long *) (ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size); |
38 | |
39 | /* Ensure the stack stays eight byte aligned. */ |
40 | misaligned = ((unsigned long) funcstack & 4) != 0; |
41 | |
42 | if ((argc > NREG_ARGS) && (argc & 1) != 0) |
43 | misaligned = !misaligned; |
44 | |
45 | if (misaligned) |
46 | funcstack -= 1; |
47 | |
48 | va_start (vl, argc); |
49 | |
50 | /* Reserve space for the on-stack arguments. */ |
51 | if (argc > NREG_ARGS) |
52 | funcstack -= (argc - NREG_ARGS); |
53 | |
54 | ucp->uc_mcontext.arm_sp = (unsigned long) funcstack; |
55 | ucp->uc_mcontext.arm_pc = (unsigned long) func; |
56 | |
57 | /* Exit to startcontext() with the next context in R4 */ |
58 | ucp->uc_mcontext.arm_r4 = (unsigned long) ucp->uc_link; |
59 | ucp->uc_mcontext.arm_lr = (unsigned long) __startcontext; |
60 | |
61 | /* The first four arguments go into registers. */ |
62 | regptr = &(ucp->uc_mcontext.arm_r0); |
63 | |
64 | for (reg = 0; (reg < argc) && (reg < NREG_ARGS); reg++) |
65 | *regptr++ = va_arg (vl, unsigned long); |
66 | |
67 | /* And the remainder on the stack. */ |
68 | for (; reg < argc; reg++) |
69 | *funcstack++ = va_arg (vl, unsigned long); |
70 | |
71 | va_end (vl); |
72 | } |
73 | weak_alias (__makecontext, makecontext) |
74 | |