1/* Save current context.
2
3 Copyright (C) 2009-2022 Free Software Foundation, Inc.
4
5 This file is part of the GNU C Library.
6
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public License as
9 published by the Free Software Foundation; either version 2.1 of the
10 License, or (at your option) any later version.
11
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, see
19 <https://www.gnu.org/licenses/>. */
20
21#include <sysdep.h>
22#include "ucontext_i.h"
23#include "ucontext-internal.h"
24
25/* int getcontext (ucontext_t *ucp)
26
27 Returns 0 on success -1 and errno on failure.
28 */
29
30 .text
31
32ENTRY(__getcontext)
33 PTR_ARG (0)
34 /* The saved context will return to the getcontext() call point
35 with a return value of 0 */
36 str xzr, [x0, oX0 + 0 * SZREG]
37
38 stp x18, x19, [x0, oX0 + 18 * SZREG]
39 stp x20, x21, [x0, oX0 + 20 * SZREG]
40 stp x22, x23, [x0, oX0 + 22 * SZREG]
41 stp x24, x25, [x0, oX0 + 24 * SZREG]
42 stp x26, x27, [x0, oX0 + 26 * SZREG]
43 stp x28, x29, [x0, oX0 + 28 * SZREG]
44 str x30, [x0, oX0 + 30 * SZREG]
45
46 /* Place LR into the saved PC, this will ensure that when
47 switching to this saved context with setcontext() control
48 will pass back to the caller of getcontext(), we have
49 already arrange to return the appropriate return value in x0
50 above. */
51 str x30, [x0, oPC]
52
53 /* Save the current SP */
54 mov x2, sp
55 str x2, [x0, oSP]
56
57 /* Initialize the pstate. */
58 str xzr, [x0, oPSTATE]
59
60 /* Figure out where to place the first context extension
61 block. */
62 add x2, x0, #oEXTENSION
63
64 /* Write the context extension fpsimd header. */
65 mov w3, #(FPSIMD_MAGIC & 0xffff)
66 movk w3, #(FPSIMD_MAGIC >> 16), lsl #16
67 str w3, [x2, #oHEAD + oMAGIC]
68 mov w3, #FPSIMD_CONTEXT_SIZE
69 str w3, [x2, #oHEAD + oSIZE]
70
71 /* Fill in the FP SIMD context. */
72 add x3, x2, #oV0 + 8 * SZVREG
73 stp q8, q9, [x3], # 2 * SZVREG
74 stp q10, q11, [x3], # 2 * SZVREG
75 stp q12, q13, [x3], # 2 * SZVREG
76 stp q14, q15, [x3], # 2 * SZVREG
77
78 add x3, x2, oFPSR
79
80 mrs x4, fpsr
81 str w4, [x3]
82
83 mrs x4, fpcr
84 str w4, [x3, oFPCR - oFPSR]
85
86 /* Write the termination context extension header. */
87 add x2, x2, #FPSIMD_CONTEXT_SIZE
88
89 str xzr, [x2, #oHEAD + oMAGIC]
90 str xzr, [x2, #oHEAD + oSIZE]
91
92 /* Grab the signal mask */
93 /* rt_sigprocmask (SIG_BLOCK, NULL, &ucp->uc_sigmask, _NSIG8) */
94 add PTR_REG (2), PTR_REG (0), #UCONTEXT_SIGMASK
95 mov x0, SIG_BLOCK
96 mov x1, 0
97 mov x3, _NSIG8
98 mov x8, SYS_ify (rt_sigprocmask)
99 svc 0
100 cbnz x0, 1f
101
102 /* Return 0 for success */
103 mov x0, 0
104 RET
1051:
106 b C_SYMBOL_NAME(__syscall_error)
107
108 PSEUDO_END (__getcontext)
109weak_alias (__getcontext, getcontext)
110

source code of glibc/sysdeps/unix/sysv/linux/aarch64/getcontext.S