1 /* Restartable Sequences Linux s390 architecture header. 2 Copyright (C) 2021-2022 Free Software Foundation, Inc. 3 4 The GNU C Library is free software; you can redistribute it and/or 5 modify it under the terms of the GNU Lesser General Public 6 License as published by the Free Software Foundation; either 7 version 2.1 of the License, or (at your option) any later version. 8 9 The GNU C Library is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public 15 License along with the GNU C Library; if not, see 16 <https://www.gnu.org/licenses/>. */ 17 18 #ifndef _SYS_RSEQ_H 19 # error "Never use <bits/rseq.h> directly; include <sys/rseq.h> instead." 20 #endif 21 22 /* RSEQ_SIG is a signature required before each abort handler code. 23 24 It is a 32-bit value that maps to actual architecture code compiled 25 into applications and libraries. It needs to be defined for each 26 architecture. When choosing this value, it needs to be taken into 27 account that generating invalid instructions may have ill effects on 28 tools like objdump, and may also have impact on the CPU speculative 29 execution efficiency in some cases. 30 31 RSEQ_SIG uses the trap4 instruction. As Linux does not make use of the 32 access-register mode nor the linkage stack this instruction will always 33 cause a special-operation exception (the trap-enabled bit in the DUCT 34 is and will stay 0). The instruction pattern is 35 b2 ff 0f ff trap4 4095(%r0) */ 36 37 #define RSEQ_SIG 0xB2FF0FFF 38