1 /* Set flags signalling availability of kernel features based on given 2 kernel version number. 3 Copyright (C) 1999-2022 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, on ia64 in 2.6.22-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 /* Support for various CLOEXEC and NONBLOCK flags was added in 58 2.6.27. */ 59 #define __ASSUME_IN_NONBLOCK 1 60 61 /* Support for preadv and pwritev was added in 2.6.30. */ 62 #define __ASSUME_PREADV 1 63 #define __ASSUME_PWRITEV 1 64 65 /* Support for sendmmsg functionality was added in 3.0. */ 66 #define __ASSUME_SENDMMSG 1 67 68 /* On most architectures, most socket syscalls are supported for all 69 supported kernel versions, but on some socketcall architectures 70 separate syscalls were only added later. */ 71 #define __ASSUME_SENDMSG_SYSCALL 1 72 #define __ASSUME_RECVMSG_SYSCALL 1 73 #define __ASSUME_ACCEPT_SYSCALL 1 74 #define __ASSUME_CONNECT_SYSCALL 1 75 #define __ASSUME_RECVFROM_SYSCALL 1 76 #define __ASSUME_SENDTO_SYSCALL 1 77 #define __ASSUME_ACCEPT4_SYSCALL 1 78 #define __ASSUME_RECVMMSG_SYSCALL 1 79 #define __ASSUME_SENDMMSG_SYSCALL 1 80 #define __ASSUME_GETSOCKOPT_SYSCALL 1 81 #define __ASSUME_SETSOCKOPT_SYSCALL 1 82 83 /* Support for SysV IPC through wired syscalls. All supported architectures 84 either support ipc syscall and/or all the ipc correspondent syscalls. */ 85 #define __ASSUME_DIRECT_SYSVIPC_SYSCALLS 1 86 /* The generic default __IPC_64 value is 0x0, however some architectures 87 require a different value of 0x100. */ 88 #define __ASSUME_SYSVIPC_DEFAULT_IPC_64 1 89 90 /* All supported architectures reserve a 32-bit for MODE field in sysvipc 91 ipc_perm. However, some kernel ABI interfaces still expect a 16-bit 92 field. This is only an issue if arch-defined IPC_PERM padding is on a 93 wrong position regarding endianness. In this case, the IPC control 94 routines (msgctl, semctl, and semtctl) requires to shift the value to 95 correct place. 96 The ABIs that requires it define __ASSUME_SYSVIPC_BROKEN_MODE_T. */ 97 98 /* Support for p{read,write}v2 was added in 4.6. However Linux default 99 implementation does not assume the __ASSUME_* and instead use a fallback 100 implementation based on p{read,write}v and returning an error for 101 non supported flags. */ 102 103 /* Support for the renameat2 system call was added in kernel 3.15. */ 104 #if __LINUX_KERNEL_VERSION >= 0x030F00 105 # define __ASSUME_RENAMEAT2 106 #endif 107 108 /* Support for the execveat syscall was added in 3.19. */ 109 #if __LINUX_KERNEL_VERSION >= 0x031300 110 # define __ASSUME_EXECVEAT 1 111 #endif 112 113 #if __LINUX_KERNEL_VERSION >= 0x040400 114 # define __ASSUME_MLOCK2 1 115 #endif 116 117 /* Support for statx was added in kernel 4.11. */ 118 #if __LINUX_KERNEL_VERSION >= 0x040B00 119 # define __ASSUME_STATX 1 120 #endif 121 122 /* Support for clone call used on fork. The signature varies across the 123 architectures with current 4 different variants: 124 125 1. long int clone (unsigned long flags, unsigned long newsp, 126 int *parent_tidptr, unsigned long tls, 127 int *child_tidptr) 128 129 2. long int clone (unsigned long newsp, unsigned long clone_flags, 130 int *parent_tidptr, int * child_tidptr, 131 unsigned long tls) 132 133 3. long int clone (unsigned long flags, unsigned long newsp, 134 int stack_size, int *parent_tidptr, 135 int *child_tidptr, unsigned long tls) 136 137 4. long int clone (unsigned long flags, unsigned long newsp, 138 int *parent_tidptr, int *child_tidptr, 139 unsigned long tls) 140 141 The fourth variant is intended to be used as the default for newer ports, 142 Also IA64 uses the third variant but with __NR_clone2 instead of 143 __NR_clone. 144 145 The macros names to define the variant used for the architecture is 146 similar to kernel: 147 148 - __ASSUME_CLONE_BACKWARDS: for variant 1. 149 - __ASSUME_CLONE_BACKWARDS2: for variant 2 (s390). 150 - __ASSUME_CLONE_BACKWARDS3: for variant 3 (microblaze). 151 - __ASSUME_CLONE_DEFAULT: for variant 4. 152 - __ASSUME_CLONE2: for clone2 with variant 3 (ia64). 153 */ 154 155 #define __ASSUME_CLONE_DEFAULT 1 156 157 /* Support for 64-bit time_t in the system call interface. When this 158 flag is set, the kernel provides a version of each of these system 159 calls that accepts 64-bit time_t: 160 161 clock_adjtime(64) 162 clock_gettime(64) 163 clock_settime(64) 164 clock_getres(_time64) 165 clock_nanosleep(_time64) 166 futex(_time64) 167 mq_timedreceive(_time64) 168 mq_timedsend(_time64) 169 ppoll(_time64) 170 pselect6(_time64) 171 rt_sigtimedwait(_time64) 172 sched_rr_get_interval(_time64) 173 timer_gettime(64) 174 timer_settime(64) 175 timerfd_gettime(64) 176 timerfd_settime(64) 177 utimensat(_time64) 178 179 On architectures where time_t has historically been 64 bits, 180 only the 64-bit version of each system call exists, and there 181 are no suffixes on the __NR_ constants. 182 183 On architectures where time_t has historically been 32 bits, 184 both 32-bit and 64-bit versions of each system call may exist, 185 depending on the kernel version. When the 64-bit version exists, 186 there is a '64' or '_time64' suffix on the name of its __NR_ 187 constant, as shown above. 188 189 This flag is always set for Linux 5.1 and later. Prior to that 190 version, it is set only for some CPU architectures and ABIs: 191 192 - __WORDSIZE == 64 - all supported architectures where pointers 193 are 64 bits also have always had 64-bit time_t. 194 195 - __WORDSIZE == 32 && __SYSCALL_WORDSIZE == 64 - this describes 196 only one supported configuration, x86's 'x32' subarchitecture, 197 where pointers are 32 bits but time_t has always been 64 bits. 198 199 __ASSUME_TIME64_SYSCALLS being set does not mean __TIMESIZE is 64, 200 and __TIMESIZE equal to 64 does not mean __ASSUME_TIME64_SYSCALLS 201 is set. All four cases are possible. */ 202 203 #if __LINUX_KERNEL_VERSION >= 0x050100 \ 204 || __WORDSIZE == 64 \ 205 || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64) 206 # define __ASSUME_TIME64_SYSCALLS 1 207 #endif 208 209 /* Linux waitid prior kernel 5.4 does not support waiting for the current 210 process group. */ 211 #if __LINUX_KERNEL_VERSION >= 0x050400 212 # define __ASSUME_WAITID_PID0_P_PGID 213 #endif 214 215 /* The faccessat2 system call was introduced across all architectures 216 in Linux 5.8. */ 217 #if __LINUX_KERNEL_VERSION >= 0x050800 218 # define __ASSUME_FACCESSAT2 1 219 #else 220 # define __ASSUME_FACCESSAT2 0 221 #endif 222 223 /* The close_range system call was introduced across all architectures 224 in Linux 5.9. */ 225 #if __LINUX_KERNEL_VERSION >= 0x050900 226 # define __ASSUME_CLOSE_RANGE 1 227 #else 228 # define __ASSUME_CLOSE_RANGE 0 229 #endif 230 231 /* The FUTEX_LOCK_PI2 operation was introduced across all architectures in Linux 232 5.14. */ 233 #if __LINUX_KERNEL_VERSION >= 0x050e00 234 # define __ASSUME_FUTEX_LOCK_PI2 1 235 #else 236 # define __ASSUME_FUTEX_LOCK_PI2 0 237 #endif 238 239 #endif /* kernel-features.h */ 240