1/* Set flags signalling availability of kernel features based on given
2 kernel version number.
3 Copyright (C) 1999-2026 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 (s390x).
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/* The mseal system call was introduced across all architectures in Linux 6.10
265 (although only supported on 64-bit CPUs). */
266/* zig patch: don't assume kernel version */
267#define __ASSUME_MSEAL 0
268
269/* The PIDFD_GET_INFO ioctl was introduced across all architectures in Linux
270 6.13. */
271/* zig patch: don't assume kernel version */
272#define __ASSUME_PIDFD_GET_INFO 0
273
274#endif /* kernel-features.h */