1/* Set flags signalling availability of kernel features based on given
2 kernel version number.
3 Copyright (C) 1999-2020 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/* The *at syscalls were introduced just after 2.6.16-rc1. On PPC
53 they were introduced in 2.6.17-rc1, on SH in 2.6.19-rc1. */
54#define __ASSUME_ATFCTS 1
55
56/* Support for inter-process robust mutexes was added in 2.6.17 (but
57 some architectures lack futex_atomic_cmpxchg_inatomic in some
58 configurations). */
59#define __ASSUME_SET_ROBUST_LIST 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
85/* Support for SysV IPC through wired syscalls. All supported architectures
86 either support ipc syscall and/or all the ipc correspondent syscalls. */
87#define __ASSUME_DIRECT_SYSVIPC_SYSCALLS 1
88/* The generic default __IPC_64 value is 0x0, however some architectures
89 require a different value of 0x100. */
90#define __ASSUME_SYSVIPC_DEFAULT_IPC_64 1
91
92/* All supported architectures reserve a 32-bit for MODE field in sysvipc
93 ipc_perm. However, some kernel ABI interfaces still expect a 16-bit
94 field. This is only an issue if arch-defined IPC_PERM padding is on a
95 wrong position regarding endianness. In this case, the IPC control
96 routines (msgctl, semctl, and semtctl) requires to shift the value to
97 correct place.
98 The ABIs that requires it define __ASSUME_SYSVIPC_BROKEN_MODE_T. */
99
100/* Support for p{read,write}v2 was added in 4.6. However Linux default
101 implementation does not assume the __ASSUME_* and instead use a fallback
102 implementation based on p{read,write}v and returning an error for
103 non supported flags. */
104
105/* Support for the renameat2 system call was added in kernel 3.15. */
106#if __LINUX_KERNEL_VERSION >= 0x030F00
107# define __ASSUME_RENAMEAT2
108#endif
109
110/* Support for the execveat syscall was added in 3.19. */
111#if __LINUX_KERNEL_VERSION >= 0x031300
112# define __ASSUME_EXECVEAT 1
113#endif
114
115#if __LINUX_KERNEL_VERSION >= 0x040400
116# define __ASSUME_MLOCK2 1
117#endif
118
119/* Support for statx was added in kernel 4.11. */
120#if __LINUX_KERNEL_VERSION >= 0x040B00
121# define __ASSUME_STATX 1
122#endif
123
124/* Support for clone call used on fork. The signature varies across the
125 architectures with current 4 different variants:
126
127 1. long int clone (unsigned long flags, unsigned long newsp,
128 int *parent_tidptr, unsigned long tls,
129 int *child_tidptr)
130
131 2. long int clone (unsigned long newsp, unsigned long clone_flags,
132 int *parent_tidptr, int * child_tidptr,
133 unsigned long tls)
134
135 3. long int clone (unsigned long flags, unsigned long newsp,
136 int stack_size, int *parent_tidptr,
137 int *child_tidptr, unsigned long tls)
138
139 4. long int clone (unsigned long flags, unsigned long newsp,
140 int *parent_tidptr, int *child_tidptr,
141 unsigned long tls)
142
143 The fourth variant is intended to be used as the default for newer ports,
144 Also IA64 uses the third variant but with __NR_clone2 instead of
145 __NR_clone.
146
147 The macros names to define the variant used for the architecture is
148 similar to kernel:
149
150 - __ASSUME_CLONE_BACKWARDS: for variant 1.
151 - __ASSUME_CLONE_BACKWARDS2: for variant 2 (s390).
152 - __ASSUME_CLONE_BACKWARDS3: for variant 3 (microblaze).
153 - __ASSUME_CLONE_DEFAULT: for variant 4.
154 - __ASSUME_CLONE2: for clone2 with variant 3 (ia64).
155 */
156
157#define __ASSUME_CLONE_DEFAULT 1
158
159/* Support for 64-bit time_t in the system call interface. When this
160 flag is set, the kernel provides a version of each of these system
161 calls that accepts 64-bit time_t:
162
163 clock_adjtime(64)
164 clock_gettime(64)
165 clock_settime(64)
166 clock_getres(_time64)
167 clock_nanosleep(_time64)
168 futex(_time64)
169 mq_timedreceive(_time64)
170 mq_timedsend(_time64)
171 ppoll(_time64)
172 pselect6(_time64)
173 rt_sigtimedwait(_time64)
174 sched_rr_get_interval(_time64)
175 timer_gettime(64)
176 timer_settime(64)
177 timerfd_gettime(64)
178 timerfd_settime(64)
179 utimensat(_time64)
180
181 On architectures where time_t has historically been 64 bits,
182 only the 64-bit version of each system call exists, and there
183 are no suffixes on the __NR_ constants.
184
185 On architectures where time_t has historically been 32 bits,
186 both 32-bit and 64-bit versions of each system call may exist,
187 depending on the kernel version. When the 64-bit version exists,
188 there is a '64' or '_time64' suffix on the name of its __NR_
189 constant, as shown above.
190
191 This flag is always set for Linux 5.1 and later. Prior to that
192 version, it is set only for some CPU architectures and ABIs:
193
194 - __WORDSIZE == 64 - all supported architectures where pointers
195 are 64 bits also have always had 64-bit time_t.
196
197 - __WORDSIZE == 32 && __SYSCALL_WORDSIZE == 64 - this describes
198 only one supported configuration, x86's 'x32' subarchitecture,
199 where pointers are 32 bits but time_t has always been 64 bits.
200
201 __ASSUME_TIME64_SYSCALLS being set does not mean __TIMESIZE is 64,
202 and __TIMESIZE equal to 64 does not mean __ASSUME_TIME64_SYSCALLS
203 is set. All four cases are possible. */
204
205#if __LINUX_KERNEL_VERSION >= 0x050100 \
206 || __WORDSIZE == 64 \
207 || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
208# define __ASSUME_TIME64_SYSCALLS 1
209#endif
210
211/* Linux waitid prior kernel 5.4 does not support waiting for the current
212 process group. */
213#if __LINUX_KERNEL_VERSION >= 0x050400
214# define __ASSUME_WAITID_PID0_P_PGID
215#endif
216
217#endif /* kernel-features.h */
218