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222 lines
8.1 KiB
C
222 lines
8.1 KiB
C
/* Set flags signalling availability of kernel features based on given
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kernel version number.
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Copyright (C) 1999-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* This file must not contain any C code. At least it must be protected
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to allow using the file also in assembler files. */
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#ifndef _LINUX_KERNEL_FEATURES_H
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#define _LINUX_KERNEL_FEATURES_H 1
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#include <bits/wordsize.h>
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#ifndef __LINUX_KERNEL_VERSION
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/* We assume the worst; all kernels should be supported. */
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# define __LINUX_KERNEL_VERSION 0
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#endif
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/* We assume for __LINUX_KERNEL_VERSION the same encoding used in
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linux/version.h. I.e., the major, minor, and subminor all get a
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byte with the major number being in the highest byte. This means
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we can do numeric comparisons.
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In the following we will define certain symbols depending on
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whether the describes kernel feature is available in the kernel
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version given by __LINUX_KERNEL_VERSION. We are not always exactly
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recording the correct versions in which the features were
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introduced. If somebody cares these values can afterwards be
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corrected. */
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/* The statfs64 syscalls are available in 2.5.74 (but not for alpha). */
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#define __ASSUME_STATFS64 1
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/* pselect/ppoll were introduced just after 2.6.16-rc1. On x86_64 and
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SH this appeared first in 2.6.19-rc1, on ia64 in 2.6.22-rc1. */
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#define __ASSUME_PSELECT 1
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/* Support for inter-process robust mutexes was added in 2.6.17 (but
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some architectures lack futex_atomic_cmpxchg_inatomic in some
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configurations). */
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#define __ASSUME_SET_ROBUST_LIST 1
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/* Support for various CLOEXEC and NONBLOCK flags was added in
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2.6.27. */
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#define __ASSUME_IN_NONBLOCK 1
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/* Support for preadv and pwritev was added in 2.6.30. */
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#define __ASSUME_PREADV 1
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#define __ASSUME_PWRITEV 1
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/* Support for sendmmsg functionality was added in 3.0. */
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#define __ASSUME_SENDMMSG 1
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/* On most architectures, most socket syscalls are supported for all
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supported kernel versions, but on some socketcall architectures
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separate syscalls were only added later. */
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#define __ASSUME_SENDMSG_SYSCALL 1
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#define __ASSUME_RECVMSG_SYSCALL 1
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#define __ASSUME_ACCEPT_SYSCALL 1
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#define __ASSUME_CONNECT_SYSCALL 1
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#define __ASSUME_RECVFROM_SYSCALL 1
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#define __ASSUME_SENDTO_SYSCALL 1
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#define __ASSUME_ACCEPT4_SYSCALL 1
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#define __ASSUME_RECVMMSG_SYSCALL 1
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#define __ASSUME_SENDMMSG_SYSCALL 1
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/* Support for SysV IPC through wired syscalls. All supported architectures
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either support ipc syscall and/or all the ipc correspondent syscalls. */
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#define __ASSUME_DIRECT_SYSVIPC_SYSCALLS 1
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/* The generic default __IPC_64 value is 0x0, however some architectures
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require a different value of 0x100. */
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#define __ASSUME_SYSVIPC_DEFAULT_IPC_64 1
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/* All supported architectures reserve a 32-bit for MODE field in sysvipc
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ipc_perm. However, some kernel ABI interfaces still expect a 16-bit
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field. This is only an issue if arch-defined IPC_PERM padding is on a
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wrong position regarding endianness. In this case, the IPC control
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routines (msgctl, semctl, and semtctl) requires to shift the value to
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correct place.
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The ABIs that requires it define __ASSUME_SYSVIPC_BROKEN_MODE_T. */
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/* Support for p{read,write}v2 was added in 4.6. However Linux default
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implementation does not assume the __ASSUME_* and instead use a fallback
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implementation based on p{read,write}v and returning an error for
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non supported flags. */
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/* Support for the renameat2 system call was added in kernel 3.15. */
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#if __LINUX_KERNEL_VERSION >= 0x030F00
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# define __ASSUME_RENAMEAT2
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#endif
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/* Support for the execveat syscall was added in 3.19. */
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#if __LINUX_KERNEL_VERSION >= 0x031300
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# define __ASSUME_EXECVEAT 1
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#endif
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#if __LINUX_KERNEL_VERSION >= 0x040400
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# define __ASSUME_MLOCK2 1
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#endif
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/* Support for statx was added in kernel 4.11. */
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#if __LINUX_KERNEL_VERSION >= 0x040B00
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# define __ASSUME_STATX 1
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#endif
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/* Support for clone call used on fork. The signature varies across the
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architectures with current 4 different variants:
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1. long int clone (unsigned long flags, unsigned long newsp,
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int *parent_tidptr, unsigned long tls,
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int *child_tidptr)
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2. long int clone (unsigned long newsp, unsigned long clone_flags,
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int *parent_tidptr, int * child_tidptr,
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unsigned long tls)
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3. long int clone (unsigned long flags, unsigned long newsp,
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int stack_size, int *parent_tidptr,
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int *child_tidptr, unsigned long tls)
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4. long int clone (unsigned long flags, unsigned long newsp,
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int *parent_tidptr, int *child_tidptr,
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unsigned long tls)
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The fourth variant is intended to be used as the default for newer ports,
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Also IA64 uses the third variant but with __NR_clone2 instead of
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__NR_clone.
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The macros names to define the variant used for the architecture is
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similar to kernel:
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- __ASSUME_CLONE_BACKWARDS: for variant 1.
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- __ASSUME_CLONE_BACKWARDS2: for variant 2 (s390).
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- __ASSUME_CLONE_BACKWARDS3: for variant 3 (microblaze).
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- __ASSUME_CLONE_DEFAULT: for variant 4.
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- __ASSUME_CLONE2: for clone2 with variant 3 (ia64).
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*/
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#define __ASSUME_CLONE_DEFAULT 1
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/* Support for 64-bit time_t in the system call interface. When this
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flag is set, the kernel provides a version of each of these system
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calls that accepts 64-bit time_t:
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clock_adjtime(64)
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clock_gettime(64)
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clock_settime(64)
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clock_getres(_time64)
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clock_nanosleep(_time64)
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futex(_time64)
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mq_timedreceive(_time64)
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mq_timedsend(_time64)
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ppoll(_time64)
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pselect6(_time64)
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rt_sigtimedwait(_time64)
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sched_rr_get_interval(_time64)
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timer_gettime(64)
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timer_settime(64)
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timerfd_gettime(64)
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timerfd_settime(64)
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utimensat(_time64)
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On architectures where time_t has historically been 64 bits,
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only the 64-bit version of each system call exists, and there
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are no suffixes on the __NR_ constants.
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On architectures where time_t has historically been 32 bits,
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both 32-bit and 64-bit versions of each system call may exist,
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depending on the kernel version. When the 64-bit version exists,
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there is a '64' or '_time64' suffix on the name of its __NR_
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constant, as shown above.
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This flag is always set for Linux 5.1 and later. Prior to that
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version, it is set only for some CPU architectures and ABIs:
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- __WORDSIZE == 64 - all supported architectures where pointers
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are 64 bits also have always had 64-bit time_t.
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- __WORDSIZE == 32 && __SYSCALL_WORDSIZE == 64 - this describes
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only one supported configuration, x86's 'x32' subarchitecture,
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where pointers are 32 bits but time_t has always been 64 bits.
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__ASSUME_TIME64_SYSCALLS being set does not mean __TIMESIZE is 64,
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and __TIMESIZE equal to 64 does not mean __ASSUME_TIME64_SYSCALLS
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is set. All four cases are possible. */
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#if __LINUX_KERNEL_VERSION >= 0x050100 \
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|| __WORDSIZE == 64 \
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|| (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
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# define __ASSUME_TIME64_SYSCALLS 1
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#endif
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/* Linux waitid prior kernel 5.4 does not support waiting for the current
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process group. */
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#if __LINUX_KERNEL_VERSION >= 0x050400
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# define __ASSUME_WAITID_PID0_P_PGID
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#endif
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/* The faccessat2 system call was introduced across all architectures
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in Linux 5.8. */
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#if __LINUX_KERNEL_VERSION >= 0x050800
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# define __ASSUME_FACCESSAT2 1
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#else
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# define __ASSUME_FACCESSAT2 0
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#endif
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#endif /* kernel-features.h */
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