Edit: indirect-return.h
/* Definition of __INDIRECT_RETURN. x86 version. Copyright (C) 2018 Free Software Foundation, Inc. This file is part of the GNU C Library. 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/>. */ #ifndef _UCONTEXT_H # error "Never include <bits/indirect-return.h> directly; use <ucontext.h> instead." #endif /* On x86, swapcontext returns via indirect branch when the shadow stack is enabled. Define __INDIRECT_RETURN to indicate whether swapcontext returns via indirect branch. */ #if defined __CET__ && (__CET__ & 2) != 0 # if __glibc_has_attribute (__indirect_return__) # define __INDIRECT_RETURN __attribute__ ((__indirect_return__)) # else /* Newer compilers provide the indirect_return attribute, but without it we can use returns_twice to affect the optimizer in the same way and avoid unsafe optimizations. */ # define __INDIRECT_RETURN __attribute__ ((__returns_twice__)) # endif #else # define __INDIRECT_RETURN #endif
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