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) 1999-2019 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    <http://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
  89 /* Support for p{read,write}v2 was added in 4.6.  However Linux default
  90    implementation does not assume the __ASSUME_* and instead use a fallback
  91    implementation based on p{read,write}v and returning an error for
  92    non supported flags.  */
  93
  94 /* Support for the renameat2 system call was added in kernel 3.15.  */
  95 #if __LINUX_KERNEL_VERSION >= 0x030F00
  96 # define __ASSUME_RENAMEAT2
  97 #endif
  98
  99 /* Support for the execveat syscall was added in 3.19.  */
 100 #if __LINUX_KERNEL_VERSION >= 0x031300
 101 # define __ASSUME_EXECVEAT      1
 102 #endif
 103
 104 #if __LINUX_KERNEL_VERSION >= 0x040400
 105 # define __ASSUME_MLOCK2 1
 106 #endif
 107
 108 /* Support for statx was added in kernel 4.11.  */
 109 #if __LINUX_KERNEL_VERSION >= 0x040B00
 110 # define __ASSUME_STATX 1
 111 #endif
 112
 113 /* Support for clone call used on fork.  The signature varies across the
 114    architectures with current 4 different variants:
 115
 116    1. long int clone (unsigned long flags, unsigned long newsp,
 117                       int *parent_tidptr, unsigned long tls,
 118                       int *child_tidptr)
 119
 120    2. long int clone (unsigned long newsp, unsigned long clone_flags,
 121                       int *parent_tidptr, int * child_tidptr,
 122                       unsigned long tls)
 123
 124    3. long int clone (unsigned long flags, unsigned long newsp,
 125                       int stack_size, int *parent_tidptr,
 126                       int *child_tidptr, unsigned long tls)
 127
 128    4. long int clone (unsigned long flags, unsigned long newsp,
 129                       int *parent_tidptr, int *child_tidptr,
 130                       unsigned long tls)
 131
 132    The fourth variant is intended to be used as the default for newer ports,
 133    Also IA64 uses the third variant but with __NR_clone2 instead of
 134    __NR_clone.
 135
 136    The macros names to define the variant used for the architecture is
 137    similar to kernel:
 138
 139    - __ASSUME_CLONE_BACKWARDS: for variant 1.
 140    - __ASSUME_CLONE_BACKWARDS2: for variant 2 (s390).
 141    - __ASSUME_CLONE_BACKWARDS3: for variant 3 (microblaze).
 142    - __ASSUME_CLONE_DEFAULT: for variant 4.
 143    - __ASSUME_CLONE2: for clone2 with variant 3 (ia64).
 144    */
 145
 146 #define __ASSUME_CLONE_DEFAULT 1
 147
 148 /* Support for 64-bit time_t in the system call interface.  When this
 149    flag is set, the kernel provides a version of each of these system
 150    calls that accepts 64-bit time_t:
 151
 152      clock_adjtime(64)
 153      clock_gettime(64)
 154      clock_settime(64)
 155      clock_getres(_time64)
 156      clock_nanosleep(_time64)
 157      futex(_time64)
 158      mq_timedreceive(_time64)
 159      mq_timedsend(_time64)
 160      ppoll(_time64)
 161      pselect6(_time64)
 162      rt_sigtimedwait(_time64)
 163      sched_rr_get_interval(_time64)
 164      timer_gettime(64)
 165      timer_settime(64)
 166      timerfd_gettime(64)
 167      timerfd_settime(64)
 168      utimensat(_time64)
 169
 170    On architectures where time_t has historically been 64 bits,
 171    only the 64-bit version of each system call exists, and there
 172    are no suffixes on the __NR_ constants.
 173
 174    On architectures where time_t has historically been 32 bits,
 175    both 32-bit and 64-bit versions of each system call may exist,
 176    depending on the kernel version.  When the 64-bit version exists,
 177    there is a '64' or '_time64' suffix on the name of its __NR_
 178    constant, as shown above.
 179
 180    This flag is always set for Linux 5.1 and later.  Prior to that
 181    version, it is set only for some CPU architectures and ABIs:
 182
 183    - __WORDSIZE == 64 - all supported architectures where pointers
 184      are 64 bits also have always had 64-bit time_t.
 185
 186    - __WORDSIZE == 32 && __SYSCALL_WORDSIZE == 64 - this describes
 187      only one supported configuration, x86's 'x32' subarchitecture,
 188      where pointers are 32 bits but time_t has always been 64 bits.
 189
 190    __ASSUME_TIME64_SYSCALLS being set does not mean __TIMESIZE is 64,
 191    and __TIMESIZE equal to 64 does not mean __ASSUME_TIME64_SYSCALLS
 192    is set.  All four cases are possible.  */
 193
 194 #if __LINUX_KERNEL_VERSION >= 0x050100                          \
 195   || __WORDSIZE == 64                                           \
 196   || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
 197 # define __ASSUME_TIME64_SYSCALLS 1
 198 #endif
 199
 200 #endif /* kernel-features.h */