zZzzZ. — /usr/include/bits

Editing: rseq.h

/* Restartable Sequences Linux x86 architecture header.
   Copyright (C) 2021 Free Software Foundation, Inc.

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
   <https://www.gnu.org/licenses/>.  */

#ifndef _SYS_RSEQ_H
# error "Never use <bits/rseq.h> directly; include <sys/rseq.h> instead."
#endif

/* RSEQ_SIG is a signature required before each abort handler code.

RSEQ_SIG is used with the following reserved undefined instructions, which
   trap in user-space:

x86-32:    0f b9 3d 53 30 05 53      ud1    0x53053053,%edi
   x86-64:    0f b9 3d 53 30 05 53      ud1    0x53053053(%rip),%edi  */

#define RSEQ_SIG        0x53053053