1/* Save current context.
2 Copyright (C) 2001-2022 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
21#include "ucontext_i.h"
22
23
24ENTRY(__getcontext)
25 /* Load address of the context data structure. */
26 movl 4(%esp), %eax
27
28 /* Return value of getcontext. EAX is the only register whose
29 value is not preserved. */
30 movl $0, oEAX(%eax)
31
32 /* Save the 32-bit register values and the return address. */
33 movl %ecx, oECX(%eax)
34 movl %edx, oEDX(%eax)
35 movl %edi, oEDI(%eax)
36 movl %esi, oESI(%eax)
37 movl %ebp, oEBP(%eax)
38 movl (%esp), %ecx
39 movl %ecx, oEIP(%eax)
40 leal 4(%esp), %ecx /* Exclude the return address. */
41 movl %ecx, oESP(%eax)
42 movl %ebx, oEBX(%eax)
43
44 /* Save the FS segment register. We don't touch the GS register
45 since it is used for threads. */
46 xorl %edx, %edx
47 movw %fs, %dx
48 movl %edx, oFS(%eax)
49
50 leal oFPREGS(%eax), %ecx
51 /* Save the floating-point context. */
52 fnstenv (%ecx)
53 /* And load it right back since the processor changes the mask.
54 Intel thought this opcode to be used in interrupt handlers which
55 would block all exceptions. */
56 fldenv (%ecx)
57
58 /* Save the current signal mask. */
59 subl $12, %esp
60 cfi_adjust_cfa_offset (12)
61 leal oSIGMASK(%eax), %eax
62 movl %eax, 8(%esp)
63 movl $0, 4(%esp)
64 movl $SIG_BLOCK, (%esp)
65 call HIDDEN_JUMPTARGET (__sigprocmask)
66 addl $12, %esp
67 cfi_adjust_cfa_offset (-12)
68 /* Propagate %eax (and errno, in case). */
69
70 ret
71PSEUDO_END(__getcontext)
72
73weak_alias (__getcontext, getcontext)
74

source code of glibc/sysdeps/mach/hurd/i386/getcontext.S