1/* Copyright (C) 2002-2016 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Andreas Jaeger <aj@suse.de>, 2002.
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 <http://www.gnu.org/licenses/>. */
18
19#include <sysdep.h>
20
21/* This is the helper code which gets called if a function which is
22 registered with 'makecontext' returns. In this case we have to
23 install the context listed in the uc_link element of the context
24 'makecontext' manipulated at the time of the 'makecontext' call.
25 If the pointer is NULL the process must terminate. */
26
27
28ENTRY(__start_context)
29 /* This removes the parameters passed to the function given to
30 'makecontext' from the stack. RBX contains the address
31 on the stack pointer for the next context. */
32 movq %rbx, %rsp
33
34 /* Don't use pop here so that stack is aligned to 16 bytes. */
35 movq (%rsp), %rdi /* This is the next context. */
36 testq %rdi, %rdi
37 je 2f /* If it is zero exit. */
38
39 call __setcontext
40 /* If this returns (which can happen if the syscall fails) we'll
41 exit the program with the return error value (-1). */
42 movq %rax,%rdi
43
442:
45 call HIDDEN_JUMPTARGET(exit)
46 /* The 'exit' call should never return. In case it does cause
47 the process to terminate. */
48 hlt
49END(__start_context)
50