1 /* Set flags signalling availability of kernel features based on given
3 Copyright (C) 1999-2024 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
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.
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.
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/>. */
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. */
23 #ifndef _LINUX_KERNEL_FEATURES_H
24 #define _LINUX_KERNEL_FEATURES_H 1
26 #include <bits/wordsize.h>
28 #ifndef __LINUX_KERNEL_VERSION
29 /* We assume the worst; all kernels should be supported. */
30 # define __LINUX_KERNEL_VERSION 0
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.
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
45 /* The statfs64 syscalls are available in 2.5.74 (but not for alpha). */
46 #define __ASSUME_STATFS64 1
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
52 /* Support for inter-process robust mutexes was added in 2.6.17 (but
53 some architectures lack futex_atomic_cmpxchg_inatomic in some
55 #define __ASSUME_SET_ROBUST_LIST 1
57 /* Support for various CLOEXEC and NONBLOCK flags was added in
59 #define __ASSUME_IN_NONBLOCK 1
61 /* Support for preadv and pwritev was added in 2.6.30. */
62 #define __ASSUME_PREADV 1
63 #define __ASSUME_PWRITEV 1
65 /* Support for sendmmsg functionality was added in 3.0. */
66 #define __ASSUME_SENDMMSG 1
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 #define __ASSUME_BIND_SYSCALL 1
83 #define __ASSUME_SOCKET_SYSCALL 1
84 #define __ASSUME_SOCKETPAIR_SYSCALL 1
85 #define __ASSUME_LISTEN_SYSCALL 1
86 #define __ASSUME_SHUTDOWN_SYSCALL 1
87 #define __ASSUME_GETSOCKNAME_SYSCALL 1
88 #define __ASSUME_GETPEERNAME_SYSCALL 1
90 /* Support for SysV IPC through wired syscalls. All supported architectures
91 either support ipc syscall and/or all the ipc correspondent syscalls. */
92 #define __ASSUME_DIRECT_SYSVIPC_SYSCALLS 1
93 /* The generic default __IPC_64 value is 0x0, however some architectures
94 require a different value of 0x100. */
95 #define __ASSUME_SYSVIPC_DEFAULT_IPC_64 1
97 /* All supported architectures reserve a 32-bit for MODE field in sysvipc
98 ipc_perm. However, some kernel ABI interfaces still expect a 16-bit
99 field. This is only an issue if arch-defined IPC_PERM padding is on a
100 wrong position regarding endianness. In this case, the IPC control
101 routines (msgctl, semctl, and semtctl) requires to shift the value to
103 The ABIs that requires it define __ASSUME_SYSVIPC_BROKEN_MODE_T. */
105 /* Support for p{read,write}v2 was added in 4.6. However Linux default
106 implementation does not assume the __ASSUME_* and instead use a fallback
107 implementation based on p{read,write}v and returning an error for
108 non supported flags. */
110 /* Support for the renameat2 system call was added in kernel 3.15. */
111 #if __LINUX_KERNEL_VERSION >= 0x030F00
112 # define __ASSUME_RENAMEAT2
115 /* Support for the execveat syscall was added in 3.19. */
116 #if __LINUX_KERNEL_VERSION >= 0x031300
117 # define __ASSUME_EXECVEAT 1
120 #if __LINUX_KERNEL_VERSION >= 0x040400
121 # define __ASSUME_MLOCK2 1
124 /* Support for statx was added in kernel 4.11. */
125 #if __LINUX_KERNEL_VERSION >= 0x040B00
126 # define __ASSUME_STATX 1
129 /* Support for clone call used on fork. The signature varies across the
130 architectures with current 4 different variants:
132 1. long int clone (unsigned long flags, unsigned long newsp,
133 int *parent_tidptr, unsigned long tls,
136 2. long int clone (unsigned long newsp, unsigned long clone_flags,
137 int *parent_tidptr, int * child_tidptr,
140 3. long int clone (unsigned long flags, unsigned long newsp,
141 int stack_size, int *parent_tidptr,
142 int *child_tidptr, unsigned long tls)
144 4. long int clone (unsigned long flags, unsigned long newsp,
145 int *parent_tidptr, int *child_tidptr,
148 The fourth variant is intended to be used as the default for newer ports,
150 The macros names to define the variant used for the architecture is
153 - __ASSUME_CLONE_BACKWARDS: for variant 1.
154 - __ASSUME_CLONE_BACKWARDS2: for variant 2 (s390).
155 - __ASSUME_CLONE_BACKWARDS3: for variant 3 (microblaze).
156 - __ASSUME_CLONE_DEFAULT: for variant 4.
159 #define __ASSUME_CLONE_DEFAULT 1
161 /* Support for 64-bit time_t in the system call interface. When this
162 flag is set, the kernel provides a version of each of these system
163 calls that accepts 64-bit time_t:
168 clock_getres(_time64)
169 clock_nanosleep(_time64)
171 mq_timedreceive(_time64)
172 mq_timedsend(_time64)
175 rt_sigtimedwait(_time64)
176 sched_rr_get_interval(_time64)
183 On architectures where time_t has historically been 64 bits,
184 only the 64-bit version of each system call exists, and there
185 are no suffixes on the __NR_ constants.
187 On architectures where time_t has historically been 32 bits,
188 both 32-bit and 64-bit versions of each system call may exist,
189 depending on the kernel version. When the 64-bit version exists,
190 there is a '64' or '_time64' suffix on the name of its __NR_
191 constant, as shown above.
193 This flag is always set for Linux 5.1 and later. Prior to that
194 version, it is set only for some CPU architectures and ABIs:
196 - __WORDSIZE == 64 - all supported architectures where pointers
197 are 64 bits also have always had 64-bit time_t.
199 - __WORDSIZE == 32 && __SYSCALL_WORDSIZE == 64 - this describes
200 only one supported configuration, x86's 'x32' subarchitecture,
201 where pointers are 32 bits but time_t has always been 64 bits.
203 __ASSUME_TIME64_SYSCALLS being set does not mean __TIMESIZE is 64,
204 and __TIMESIZE equal to 64 does not mean __ASSUME_TIME64_SYSCALLS
205 is set. All four cases are possible. */
207 #if __LINUX_KERNEL_VERSION >= 0x050100 \
208 || __WORDSIZE == 64 \
209 || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
210 # define __ASSUME_TIME64_SYSCALLS 1
213 /* Linux waitid prior kernel 5.4 does not support waiting for the current
215 #if __LINUX_KERNEL_VERSION >= 0x050400
216 # define __ASSUME_WAITID_PID0_P_PGID
219 /* The faccessat2 system call was introduced across all architectures
221 #if __LINUX_KERNEL_VERSION >= 0x050800
222 # define __ASSUME_FACCESSAT2 1
224 # define __ASSUME_FACCESSAT2 0
227 /* The close_range system call was introduced across all architectures
229 #if __LINUX_KERNEL_VERSION >= 0x050900
230 # define __ASSUME_CLOSE_RANGE 1
232 # define __ASSUME_CLOSE_RANGE 0
235 /* The FUTEX_LOCK_PI2 operation was introduced across all architectures in Linux
237 #if __LINUX_KERNEL_VERSION >= 0x050e00
238 # define __ASSUME_FUTEX_LOCK_PI2 1
240 # define __ASSUME_FUTEX_LOCK_PI2 0
243 /* The clone3 system call was introduced across on most architectures in
244 Linux 5.3. Not all ports implements it, so it should be used along
245 HAVE_CLONE3_WRAPPER define. */
246 #if __LINUX_KERNEL_VERSION >= 0x050300
247 # define __ASSUME_CLONE3 1
249 # define __ASSUME_CLONE3 0
252 /* The fchmodat2 system call was introduced across all architectures
254 #if __LINUX_KERNEL_VERSION >= 0x060600
255 # define __ASSUME_FCHMODAT2 1
257 # define __ASSUME_FCHMODAT2 0
260 #endif /* kernel-features.h */