1 /* Set flags signalling availability of kernel features based on given
2 kernel version number.
3 Copyright (C) 1999-2023 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 #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
89
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
96
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
102 correct place.
103 The ABIs that requires it define __ASSUME_SYSVIPC_BROKEN_MODE_T. */
104
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. */
109
110 /* Support for the renameat2 system call was added in kernel 3.15. */
111 #if __LINUX_KERNEL_VERSION >= 0x030F00
112 # define __ASSUME_RENAMEAT2
113 #endif
114
115 /* Support for the execveat syscall was added in 3.19. */
116 #if __LINUX_KERNEL_VERSION >= 0x031300
117 # define __ASSUME_EXECVEAT 1
118 #endif
119
120 #if __LINUX_KERNEL_VERSION >= 0x040400
121 # define __ASSUME_MLOCK2 1
122 #endif
123
124 /* Support for statx was added in kernel 4.11. */
125 #if __LINUX_KERNEL_VERSION >= 0x040B00
126 # define __ASSUME_STATX 1
127 #endif
128
129 /* Support for clone call used on fork. The signature varies across the
130 architectures with current 4 different variants:
131
132 1. long int clone (unsigned long flags, unsigned long newsp,
133 int *parent_tidptr, unsigned long tls,
134 int *child_tidptr)
135
136 2. long int clone (unsigned long newsp, unsigned long clone_flags,
137 int *parent_tidptr, int * child_tidptr,
138 unsigned long tls)
139
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)
143
144 4. long int clone (unsigned long flags, unsigned long newsp,
145 int *parent_tidptr, int *child_tidptr,
146 unsigned long tls)
147
148 The fourth variant is intended to be used as the default for newer ports,
149 Also IA64 uses the third variant but with __NR_clone2 instead of
150 __NR_clone.
151
152 The macros names to define the variant used for the architecture is
153 similar to kernel:
154
155 - __ASSUME_CLONE_BACKWARDS: for variant 1.
156 - __ASSUME_CLONE_BACKWARDS2: for variant 2 (s390).
157 - __ASSUME_CLONE_BACKWARDS3: for variant 3 (microblaze).
158 - __ASSUME_CLONE_DEFAULT: for variant 4.
159 - __ASSUME_CLONE2: for clone2 with variant 3 (ia64).
160 */
161
162 #define __ASSUME_CLONE_DEFAULT 1
163
164 /* Support for 64-bit time_t in the system call interface. When this
165 flag is set, the kernel provides a version of each of these system
166 calls that accepts 64-bit time_t:
167
168 clock_adjtime(64)
169 clock_gettime(64)
170 clock_settime(64)
171 clock_getres(_time64)
172 clock_nanosleep(_time64)
173 futex(_time64)
174 mq_timedreceive(_time64)
175 mq_timedsend(_time64)
176 ppoll(_time64)
177 pselect6(_time64)
178 rt_sigtimedwait(_time64)
179 sched_rr_get_interval(_time64)
180 timer_gettime(64)
181 timer_settime(64)
182 timerfd_gettime(64)
183 timerfd_settime(64)
184 utimensat(_time64)
185
186 On architectures where time_t has historically been 64 bits,
187 only the 64-bit version of each system call exists, and there
188 are no suffixes on the __NR_ constants.
189
190 On architectures where time_t has historically been 32 bits,
191 both 32-bit and 64-bit versions of each system call may exist,
192 depending on the kernel version. When the 64-bit version exists,
193 there is a '64' or '_time64' suffix on the name of its __NR_
194 constant, as shown above.
195
196 This flag is always set for Linux 5.1 and later. Prior to that
197 version, it is set only for some CPU architectures and ABIs:
198
199 - __WORDSIZE == 64 - all supported architectures where pointers
200 are 64 bits also have always had 64-bit time_t.
201
202 - __WORDSIZE == 32 && __SYSCALL_WORDSIZE == 64 - this describes
203 only one supported configuration, x86's 'x32' subarchitecture,
204 where pointers are 32 bits but time_t has always been 64 bits.
205
206 __ASSUME_TIME64_SYSCALLS being set does not mean __TIMESIZE is 64,
207 and __TIMESIZE equal to 64 does not mean __ASSUME_TIME64_SYSCALLS
208 is set. All four cases are possible. */
209
210 #if __LINUX_KERNEL_VERSION >= 0x050100 \
211 || __WORDSIZE == 64 \
212 || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
213 # define __ASSUME_TIME64_SYSCALLS 1
214 #endif
215
216 /* Linux waitid prior kernel 5.4 does not support waiting for the current
217 process group. */
218 #if __LINUX_KERNEL_VERSION >= 0x050400
219 # define __ASSUME_WAITID_PID0_P_PGID
220 #endif
221
222 /* The faccessat2 system call was introduced across all architectures
223 in Linux 5.8. */
224 #if __LINUX_KERNEL_VERSION >= 0x050800
225 # define __ASSUME_FACCESSAT2 1
226 #else
227 # define __ASSUME_FACCESSAT2 0
228 #endif
229
230 /* The close_range system call was introduced across all architectures
231 in Linux 5.9. */
232 #if __LINUX_KERNEL_VERSION >= 0x050900
233 # define __ASSUME_CLOSE_RANGE 1
234 #else
235 # define __ASSUME_CLOSE_RANGE 0
236 #endif
237
238 /* The FUTEX_LOCK_PI2 operation was introduced across all architectures in Linux
239 5.14. */
240 #if __LINUX_KERNEL_VERSION >= 0x050e00
241 # define __ASSUME_FUTEX_LOCK_PI2 1
242 #else
243 # define __ASSUME_FUTEX_LOCK_PI2 0
244 #endif
245
246 /* The clone3 system call was introduced across on most architectures in
247 Linux 5.3. Not all ports implements it, so it should be used along
248 HAVE_CLONE3_WRAPPER define. */
249 #if __LINUX_KERNEL_VERSION >= 0x050300
250 # define __ASSUME_CLONE3 1
251 #else
252 # define __ASSUME_CLONE3 0
253 #endif
254
255 #endif /* kernel-features.h */