sysdeps/unix/sysv/linux/kernel-features.h

   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 #define __ASSUME_BIND_SYSCALL           1
  83 #define __ASSUME_SOCKET_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 /* The faccessat2 system call was introduced across all architectures
 218    in Linux 5.8.  */
 219 #if __LINUX_KERNEL_VERSION >= 0x050800
 220 # define __ASSUME_FACCESSAT2 1
 221 #else
 222 # define __ASSUME_FACCESSAT2 0
 223 #endif
 224
 225 /* The close_range system call was introduced across all architectures
 226    in Linux 5.9.  */
 227 #if __LINUX_KERNEL_VERSION >= 0x050900
 228 # define __ASSUME_CLOSE_RANGE 1
 229 #else
 230 # define __ASSUME_CLOSE_RANGE 0
 231 #endif
 232
 233 /* The FUTEX_LOCK_PI2 operation was introduced across all architectures in Linux
 234    5.14.  */
 235 #if __LINUX_KERNEL_VERSION >= 0x050e00
 236 # define __ASSUME_FUTEX_LOCK_PI2 1
 237 #else
 238 # define __ASSUME_FUTEX_LOCK_PI2 0
 239 #endif
 240
 241 #endif /* kernel-features.h */