1/* Set current context.
2 Copyright (C) 2009-2022 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 "ucontext-macros.h"
20
21/* int __setcontext (const ucontext_t *ucp)
22
23 Restores the machine context in UCP and thereby resumes execution
24 in that context.
25
26 This implementation is intended to be used for *synchronous* context
27 switches only. Therefore, it does not have to restore anything
28 other than the PRESERVED state. */
29
30 .text
31LEAF (__setcontext)
32
33 mv t0, a0 /* Save ucp into t0. */
34
35/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, NULL, _NSIG8) */
36 li a3, _NSIG8
37 mv a2, zero
38 add a1, a0, UCONTEXT_SIGMASK
39 li a0, SIG_SETMASK
40
41 li a7, SYS_ify (rt_sigprocmask)
42 scall
43
44 bltz a0, 99f
45
46 cfi_def_cfa (t0, 0)
47
48#ifndef __riscv_float_abi_soft
49 lw t1, MCONTEXT_FSR(t0)
50
51 RESTORE_FP_REG_CFI (fs0, 8, t0)
52 RESTORE_FP_REG_CFI (fs1, 9, t0)
53 RESTORE_FP_REG_CFI (fs2, 18, t0)
54 RESTORE_FP_REG_CFI (fs3, 19, t0)
55 RESTORE_FP_REG_CFI (fs4, 20, t0)
56 RESTORE_FP_REG_CFI (fs5, 21, t0)
57 RESTORE_FP_REG_CFI (fs6, 22, t0)
58 RESTORE_FP_REG_CFI (fs7, 23, t0)
59 RESTORE_FP_REG_CFI (fs8, 24, t0)
60 RESTORE_FP_REG_CFI (fs9, 25, t0)
61 RESTORE_FP_REG_CFI (fs10, 26, t0)
62 RESTORE_FP_REG_CFI (fs11, 27, t0)
63
64 fssr t1
65#endif /* __riscv_float_abi_soft */
66
67 /* Note the contents of argument registers will be random
68 unless makecontext() has been called. */
69 RESTORE_INT_REG (t1, 0, t0)
70 RESTORE_INT_REG_CFI (ra, 1, t0)
71 RESTORE_INT_REG (sp, 2, t0)
72 RESTORE_INT_REG_CFI (s0, 8, t0)
73 RESTORE_INT_REG_CFI (s1, 9, t0)
74 RESTORE_INT_REG (a0, 10, t0)
75 RESTORE_INT_REG (a1, 11, t0)
76 RESTORE_INT_REG (a2, 12, t0)
77 RESTORE_INT_REG (a3, 13, t0)
78 RESTORE_INT_REG (a4, 14, t0)
79 RESTORE_INT_REG (a5, 15, t0)
80 RESTORE_INT_REG (a6, 16, t0)
81 RESTORE_INT_REG (a7, 17, t0)
82 RESTORE_INT_REG_CFI (s2, 18, t0)
83 RESTORE_INT_REG_CFI (s3, 19, t0)
84 RESTORE_INT_REG_CFI (s4, 20, t0)
85 RESTORE_INT_REG_CFI (s5, 21, t0)
86 RESTORE_INT_REG_CFI (s6, 22, t0)
87 RESTORE_INT_REG_CFI (s7, 23, t0)
88 RESTORE_INT_REG_CFI (s8, 24, t0)
89 RESTORE_INT_REG_CFI (s9, 25, t0)
90 RESTORE_INT_REG_CFI (s10, 26, t0)
91 RESTORE_INT_REG_CFI (s11, 27, t0)
92
93 jr t1
94
9599: j __syscall_error
96
97END (__setcontext)
98libc_hidden_def (__setcontext)
99weak_alias (__setcontext, setcontext)
100
101LEAF (__start_context)
102
103 /* Terminate call stack by noting ra == 0. Happily, s0 == 0 here. */
104 cfi_register (ra, s0)
105
106 /* Call the function passed to makecontext. */
107 jalr s1
108
109 /* Invoke subsequent context if present, else exit(0). */
110 mv a0, s2
111 beqz s2, 1f
112 jal HIDDEN_JUMPTARGET (__setcontext)
1131: j HIDDEN_JUMPTARGET (exit)
114
115END (__start_context)
116

source code of glibc/sysdeps/unix/sysv/linux/riscv/setcontext.S