diff options
Diffstat (limited to 'libc/sysdeps/linux/x86_64/__start_context.S')
| -rw-r--r-- | libc/sysdeps/linux/x86_64/__start_context.S | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/x86_64/__start_context.S b/libc/sysdeps/linux/x86_64/__start_context.S new file mode 100644 index 000000000..9f2ee2373 --- /dev/null +++ b/libc/sysdeps/linux/x86_64/__start_context.S @@ -0,0 +1,49 @@ +/* Copyright (C) 2002-2012 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Andreas Jaeger <aj@suse.de>, 2002. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + +/* This is the helper code which gets called if a function which is + registered with 'makecontext' returns. In this case we have to + install the context listed in the uc_link element of the context + 'makecontext' manipulated at the time of the 'makecontext' call. + If the pointer is NULL the process must terminate. */ + + +ENTRY(__start_context) + /* This removes the parameters passed to the function given to + 'makecontext' from the stack. RBX contains the address + on the stack pointer for the next context. */ + movq %rbx, %rsp + + popq %rdi /* This is the next context. */ + cfi_adjust_cfa_offset(-8) + testq %rdi, %rdi + je 2f /* If it is zero exit. */ + + call JUMPTARGET(__setcontext) + /* If this returns (which can happen if the syscall fails) we'll + exit the program with the return error value (-1). */ + movq %rax,%rdi + +2: + call HIDDEN_JUMPTARGET(exit) + /* The 'exit' call should never return. In case it does cause + the process to terminate. */ + hlt +END(__start_context) |