kernel-features.h (9500B) - Raw
1 /* Set flags signalling availability of kernel features based on given 2 kernel version number. 3 Copyright (C) 1999-2025 Free Software Foundation, Inc. 4 This file is part of the GNU C Library. 5 6 The GNU C Library is free software; you can redistribute it and/or 7 modify it under the terms of the GNU Lesser General Public 8 License as published by the Free Software Foundation; either 9 version 2.1 of the License, or (at your option) any later version. 10 11 The GNU C Library is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 Lesser General Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with the GNU C Library; if not, see 18 <https://www.gnu.org/licenses/>. */ 19 20 /* This file must not contain any C code. At least it must be protected 21 to allow using the file also in assembler files. */ 22 23 #ifndef _LINUX_KERNEL_FEATURES_H 24 #define _LINUX_KERNEL_FEATURES_H 1 25 26 #include <bits/wordsize.h> 27 28 #ifndef __LINUX_KERNEL_VERSION 29 /* We assume the worst; all kernels should be supported. */ 30 # define __LINUX_KERNEL_VERSION 0 31 #endif 32 33 /* We assume for __LINUX_KERNEL_VERSION the same encoding used in 34 linux/version.h. I.e., the major, minor, and subminor all get a 35 byte with the major number being in the highest byte. This means 36 we can do numeric comparisons. 37 38 In the following we will define certain symbols depending on 39 whether the describes kernel feature is available in the kernel 40 version given by __LINUX_KERNEL_VERSION. We are not always exactly 41 recording the correct versions in which the features were 42 introduced. If somebody cares these values can afterwards be 43 corrected. */ 44 45 /* The statfs64 syscalls are available in 2.5.74 (but not for alpha). */ 46 #define __ASSUME_STATFS64 1 47 48 /* pselect/ppoll were introduced just after 2.6.16-rc1. On x86_64 and 49 SH this appeared first in 2.6.19-rc1. */ 50 #define __ASSUME_PSELECT 1 51 52 /* Support for inter-process robust mutexes was added in 2.6.17 (but 53 some architectures lack futex_atomic_cmpxchg_inatomic in some 54 configurations). */ 55 #define __ASSUME_SET_ROBUST_LIST 1 56 57 /* The termios2 interface was introduced across all architectures except 58 Alpha in kernel 2.6.22. */ 59 #define __ASSUME_TERMIOS2 1 60 61 /* Support for various CLOEXEC and NONBLOCK flags was added in 62 2.6.27. */ 63 #define __ASSUME_IN_NONBLOCK 1 64 65 /* Support for preadv and pwritev was added in 2.6.30. */ 66 #define __ASSUME_PREADV 1 67 #define __ASSUME_PWRITEV 1 68 69 /* Support for sendmmsg functionality was added in 3.0. */ 70 #define __ASSUME_SENDMMSG 1 71 72 /* On most architectures, most socket syscalls are supported for all 73 supported kernel versions, but on some socketcall architectures 74 separate syscalls were only added later. */ 75 #define __ASSUME_SENDMSG_SYSCALL 1 76 #define __ASSUME_RECVMSG_SYSCALL 1 77 #define __ASSUME_ACCEPT_SYSCALL 1 78 #define __ASSUME_CONNECT_SYSCALL 1 79 #define __ASSUME_RECVFROM_SYSCALL 1 80 #define __ASSUME_SENDTO_SYSCALL 1 81 #define __ASSUME_ACCEPT4_SYSCALL 1 82 #define __ASSUME_RECVMMSG_SYSCALL 1 83 #define __ASSUME_SENDMMSG_SYSCALL 1 84 #define __ASSUME_GETSOCKOPT_SYSCALL 1 85 #define __ASSUME_SETSOCKOPT_SYSCALL 1 86 #define __ASSUME_BIND_SYSCALL 1 87 #define __ASSUME_SOCKET_SYSCALL 1 88 #define __ASSUME_SOCKETPAIR_SYSCALL 1 89 #define __ASSUME_LISTEN_SYSCALL 1 90 #define __ASSUME_SHUTDOWN_SYSCALL 1 91 #define __ASSUME_GETSOCKNAME_SYSCALL 1 92 #define __ASSUME_GETPEERNAME_SYSCALL 1 93 94 /* Support for SysV IPC through wired syscalls. All supported architectures 95 either support ipc syscall and/or all the ipc correspondent syscalls. */ 96 #define __ASSUME_DIRECT_SYSVIPC_SYSCALLS 1 97 /* The generic default __IPC_64 value is 0x0, however some architectures 98 require a different value of 0x100. */ 99 #define __ASSUME_SYSVIPC_DEFAULT_IPC_64 1 100 101 /* All supported architectures reserve a 32-bit for MODE field in sysvipc 102 ipc_perm. However, some kernel ABI interfaces still expect a 16-bit 103 field. This is only an issue if arch-defined IPC_PERM padding is on a 104 wrong position regarding endianness. In this case, the IPC control 105 routines (msgctl, semctl, and semtctl) requires to shift the value to 106 correct place. 107 The ABIs that requires it define __ASSUME_SYSVIPC_BROKEN_MODE_T. */ 108 109 /* Support for p{read,write}v2 was added in 4.6. However Linux default 110 implementation does not assume the __ASSUME_* and instead use a fallback 111 implementation based on p{read,write}v and returning an error for 112 non supported flags. */ 113 114 /* Support for the renameat2 system call was added in kernel 3.15. */ 115 #if __LINUX_KERNEL_VERSION >= 0x030F00 116 # define __ASSUME_RENAMEAT2 117 #endif 118 119 /* Support for the execveat syscall was added in 3.19. */ 120 #if __LINUX_KERNEL_VERSION >= 0x031300 121 # define __ASSUME_EXECVEAT 1 122 #endif 123 124 #if __LINUX_KERNEL_VERSION >= 0x040400 125 # define __ASSUME_MLOCK2 1 126 #endif 127 128 /* Support for statx was added in kernel 4.11. */ 129 #if __LINUX_KERNEL_VERSION >= 0x040B00 130 # define __ASSUME_STATX 1 131 #endif 132 133 /* Support for clone call used on fork. The signature varies across the 134 architectures with current 4 different variants: 135 136 1. long int clone (unsigned long flags, unsigned long newsp, 137 int *parent_tidptr, unsigned long tls, 138 int *child_tidptr) 139 140 2. long int clone (unsigned long newsp, unsigned long clone_flags, 141 int *parent_tidptr, int * child_tidptr, 142 unsigned long tls) 143 144 3. long int clone (unsigned long flags, unsigned long newsp, 145 int stack_size, int *parent_tidptr, 146 int *child_tidptr, unsigned long tls) 147 148 4. long int clone (unsigned long flags, unsigned long newsp, 149 int *parent_tidptr, int *child_tidptr, 150 unsigned long tls) 151 152 The fourth variant is intended to be used as the default for newer ports, 153 154 The macros names to define the variant used for the architecture is 155 similar to kernel: 156 157 - __ASSUME_CLONE_BACKWARDS: for variant 1. 158 - __ASSUME_CLONE_BACKWARDS2: for variant 2 (s390). 159 - __ASSUME_CLONE_BACKWARDS3: for variant 3 (microblaze). 160 - __ASSUME_CLONE_DEFAULT: for variant 4. 161 */ 162 163 #define __ASSUME_CLONE_DEFAULT 1 164 165 /* Support for 64-bit time_t in the system call interface. When this 166 flag is set, the kernel provides a version of each of these system 167 calls that accepts 64-bit time_t: 168 169 clock_adjtime(64) 170 clock_gettime(64) 171 clock_settime(64) 172 clock_getres(_time64) 173 clock_nanosleep(_time64) 174 futex(_time64) 175 mq_timedreceive(_time64) 176 mq_timedsend(_time64) 177 ppoll(_time64) 178 pselect6(_time64) 179 rt_sigtimedwait(_time64) 180 sched_rr_get_interval(_time64) 181 timer_gettime(64) 182 timer_settime(64) 183 timerfd_gettime(64) 184 timerfd_settime(64) 185 utimensat(_time64) 186 187 On architectures where time_t has historically been 64 bits, 188 only the 64-bit version of each system call exists, and there 189 are no suffixes on the __NR_ constants. 190 191 On architectures where time_t has historically been 32 bits, 192 both 32-bit and 64-bit versions of each system call may exist, 193 depending on the kernel version. When the 64-bit version exists, 194 there is a '64' or '_time64' suffix on the name of its __NR_ 195 constant, as shown above. 196 197 This flag is always set for Linux 5.1 and later. Prior to that 198 version, it is set only for some CPU architectures and ABIs: 199 200 - __WORDSIZE == 64 - all supported architectures where pointers 201 are 64 bits also have always had 64-bit time_t. 202 203 - __WORDSIZE == 32 && __SYSCALL_WORDSIZE == 64 - this describes 204 only one supported configuration, x86's 'x32' subarchitecture, 205 where pointers are 32 bits but time_t has always been 64 bits. 206 207 __ASSUME_TIME64_SYSCALLS being set does not mean __TIMESIZE is 64, 208 and __TIMESIZE equal to 64 does not mean __ASSUME_TIME64_SYSCALLS 209 is set. All four cases are possible. */ 210 211 #if __LINUX_KERNEL_VERSION >= 0x050100 \ 212 || __WORDSIZE == 64 \ 213 || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64) 214 # define __ASSUME_TIME64_SYSCALLS 1 215 #endif 216 217 /* Linux waitid prior kernel 5.4 does not support waiting for the current 218 process group. */ 219 #if __LINUX_KERNEL_VERSION >= 0x050400 220 # define __ASSUME_WAITID_PID0_P_PGID 221 #endif 222 223 /* The faccessat2 system call was introduced across all architectures 224 in Linux 5.8. */ 225 #if __LINUX_KERNEL_VERSION >= 0x050800 226 # define __ASSUME_FACCESSAT2 1 227 #else 228 # define __ASSUME_FACCESSAT2 0 229 #endif 230 231 /* The close_range system call was introduced across all architectures 232 in Linux 5.9. */ 233 #if __LINUX_KERNEL_VERSION >= 0x050900 234 # define __ASSUME_CLOSE_RANGE 1 235 #else 236 # define __ASSUME_CLOSE_RANGE 0 237 #endif 238 239 /* The FUTEX_LOCK_PI2 operation was introduced across all architectures in Linux 240 5.14. */ 241 #if __LINUX_KERNEL_VERSION >= 0x050e00 242 # define __ASSUME_FUTEX_LOCK_PI2 1 243 #else 244 # define __ASSUME_FUTEX_LOCK_PI2 0 245 #endif 246 247 /* The clone3 system call was introduced across on most architectures in 248 Linux 5.3. Not all ports implements it, so it should be used along 249 HAVE_CLONE3_WRAPPER define. */ 250 #if __LINUX_KERNEL_VERSION >= 0x050300 251 # define __ASSUME_CLONE3 1 252 #else 253 # define __ASSUME_CLONE3 0 254 #endif 255 256 /* The fchmodat2 system call was introduced across all architectures 257 in Linux 6.6. */ 258 #if __LINUX_KERNEL_VERSION >= 0x060600 259 # define __ASSUME_FCHMODAT2 1 260 #else 261 # define __ASSUME_FCHMODAT2 0 262 #endif 263 264 #endif /* kernel-features.h */