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dd481ccffd
glibc/sysdeps/unix/sysv/linux/kernel-features.h
Joseph Myers dd481ccffd Fix __ASSUME_ACCEPT4 issues (bug 16609). 
In <https://sourceware.org/ml/libc-alpha/2013-12/msg00008.html>,
Aurelien noted issues with the definition of __ASSUME_ACCEPT4, which I
discussed in more detail in
<https://sourceware.org/ml/libc-alpha/2013-12/msg00014.html>; these
are now bug 16609.

As previously noted, __ASSUME_ACCEPT4 is used in two ways:

* In OS-independent code, to mean "accept4 can be assumed to work
  rather than fail with ENOSYS".  It doesn't matter whether it's
  implemented with socketcall or a separate syscall.

* In Linux-specific code, to mean "the socketcall multiplex syscall
  can be assumed to handle the accept4 operation.  When used in
  Linux-specific code, it *never* refers to anything relating to the
  accept4 syscall, only to the socketcall multiplexer.

This patch splits the macro into separate __ASSUME_ACCEPT4_SOCKETCALL,
__ASSUME_ACCEPT4_SYSCALL and __ASSUME_ACCEPT4 to clarify the different
cases involved.  A macro __ASSUME_SOCKETCALL is added for convenience
in writing logic relating to all socketcall architectures.  In
addition, to address the issue of architectures where socketcall
support for accept4 was added before a separate syscall was added (and
so the separate syscall should not be used unless known to be present
or fallback to socketcall is available), a fourth macro
__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL is added to indicate that the
syscall became available at the same time as socketcall support.  This
is then used in the relevant places in a conditional determining
whether to undefine __NR_accept4 (the simple approach to avoiding the
syscall's presence causing problems; I didn't try to implement runtime
fallback from the syscall to socketcall).

Architecture-specific note: alpha defined __ASSUME_ACCEPT4 for 2.6.33
and later, but actually the syscall was added for alpha in 3.2, so
this patch uses the correct condition for __ASSUME_ACCEPT4_SYSCALL
there.

Tested x86_64, including that disassembly of the installed shared
libraries is unchanged by this patch.

	[BZ #16609]
	* sysdeps/unix/sysv/linux/kernel-features.h [__i386__ ||
	__powerpc__ || __s390__ || __sh__ || __sparc__]
	(__ASSUME_SOCKETCALL): Define.
	[__LINUX_KERNEL_VERSION && __ASSUME_SOCKETCALL]
	(__ASSUME_ACCEPT4_SOCKETCALL): Likewise.
	[(__LINUX_KERNEL_VERSION >= 0x02061c && (__x86_64__ || __sparc__))
	|| (__LINUX_KERNEL_VERSION >= 0x020625 && (__powerpc__ ||
	__sh__))] (__ASSUME_ACCEPT4_SYSCALL): Likewise.
	[__sparc__] (__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL): Likewise.
	[__ASSUME_ACCEPT4_SOCKETCALL || __ASSUME_ACCEPT4_SYSCALL]
	(__ASSUME_ACCEPT4): Define instead of using previous
	[__LINUX_KERNEL_VERSION >= 0x02061c && (__i386__ || __x86_64__ ||
	__powerpc__ || __sparc__ || __s390__)] condition.
	* sysdeps/unix/sysv/linux/aarch64/kernel-features.h
	(__ASSUME_ACCEPT4): Change to __ASSUME_ACCEPT4_SYSCALL.
	* sysdeps/unix/sysv/linux/accept4.c [__ASSUME_SOCKETCALL &&
	!__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL &&
	!__ASSUME_ACCEPT4_SYSCALL] (__NR_accept4): Undefine.
	[!__ASSUME_ACCEPT4]: Change condition to
	[!__ASSUME_ACCEPT4_SOCKETCALL].
	* sysdeps/unix/sysv/linux/alpha/kernel-features.h
	(__ASSUME_ACCEPT4): Change to __ASSUME_ACCEPT4_SYSCALL.  Correct
	condition to [__LINUX_KERNEL_VERSION >= 0x030200].
	* sysdeps/unix/sysv/linux/arm/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020624] (__ASSUME_ACCEPT4): Change to
	__ASSUME_ACCEPT4_SYSCALL.
	* sysdeps/unix/sysv/linux/i386/accept4.S [__ASSUME_ACCEPT4]:
	Change conditions to [__ASSUME_ACCEPT4_SOCKETCALL].
	* sysdeps/unix/sysv/linux/ia64/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x030300] (__ASSUME_ACCEPT4): Change to
	__ASSUME_ACCEPT4_SYSCALL.
	* sysdeps/unix/sysv/linux/internal_accept4.S [__ASSUME_SOCKETCALL
	&& !__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL &&
	!__ASSUME_ACCEPT4_SYSCALL] (__NR_accept4): Undefine.
	[__ASSUME_ACCEPT4]: Change condition to
	[__ASSUME_ACCEPT4_SOCKETCALL].
	* sysdeps/unix/sysv/linux/m68k/kernel-features.h
	(__ASSUME_SOCKETCALL): Define.
	[__LINUX_KERNEL_VERSION >= 0x02061c] (__ASSUME_ACCEPT4): Remove.
	* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
	(__ASSUME_SOCKETCALL): Define.
	(__ASSUME_ACCEPT4): Remove.
	[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_ACCEPT4_SYSCALL):
	Define.
	* sysdeps/unix/sysv/linux/mips/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x02061f] (__ASSUME_ACCEPT4_SYSCALL):
	Likewise.
	* sysdeps/unix/sysv/linux/tile/kernel-features.h
	(__ASSUME_ACCEPT4): Change to __ASSUME_ACCEPT4_SYSCALL.

	* sysdeps/unix/sysv/linux/hppa/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020622] (__ASSUME_ACCEPT4_SYSCALL):
	Define.
2014-02-20 17:50:31 +00:00

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/* Set flags signalling availability of kernel features based on given
kernel version number.
Copyright (C) 1999-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* This file must not contain any C code. At least it must be protected
to allow using the file also in assembler files. */
#ifndef __LINUX_KERNEL_VERSION
/* We assume the worst; all kernels should be supported. */
# define __LINUX_KERNEL_VERSION 0
#endif
/* We assume for __LINUX_KERNEL_VERSION the same encoding used in
linux/version.h. I.e., the major, minor, and subminor all get a
byte with the major number being in the highest byte. This means
we can do numeric comparisons.
In the following we will define certain symbols depending on
whether the describes kernel feature is available in the kernel
version given by __LINUX_KERNEL_VERSION. We are not always exactly
recording the correct versions in which the features were
introduced. If somebody cares these values can afterwards be
corrected. */
/* The sendfile syscall was introduced in 2.2.0. */
#define __ASSUME_SENDFILE 1
/* Some architectures use the socketcall multiplexer for some or all
socket-related operations, via a socket.S file in glibc, instead of
separate syscalls. __ASSUME_SOCKETCALL is defined for such
architectures. */
#if defined __i386__ \
|| defined __powerpc__ \
|| defined __s390__ \
|| defined __sh__ \
|| defined __sparc__
# define __ASSUME_SOCKETCALL 1
#endif
/* Linux 2.3.39 introduced IPC64. Except for powerpc. Linux 2.4.0 on
PPC introduced a correct IPC64. But PowerPC64 does not support a
separate 64-bit syscall, already 64-bit. */
#ifndef __powerpc64__
# define __ASSUME_IPC64 1
#endif
/* The changed st_ino field appeared in 2.4.0-test6. However, SH is lame,
and still does not have a 64-bit inode field. */
#ifndef __sh__
# define __ASSUME_ST_INO_64_BIT 1
#endif
/* The getdents64 syscall was introduced in 2.4.0-test7 (but later for
MIPS n32). */
#define __ASSUME_GETDENTS64_SYSCALL 1
/* The statfs64 syscalls are available in 2.5.74 (but not for alpha). */
#define __ASSUME_STATFS64 1
/* The utimes syscall has been available for some architectures
forever. For x86 it was introduced after 2.5.75, for x86-64,
ppc, and ppc64 it was introduced in 2.6.0-test3, for s390 it was
introduced in 2.6.21-rc5. */
#if defined __sparc__ \
|| defined __i386__ \
|| defined __x86_64__ \
|| defined __powerpc__ \
|| defined __sh__ \
|| (defined __s390__ && __LINUX_KERNEL_VERSION >= 0x020616)
# define __ASSUME_UTIMES 1
#endif
/* pselect/ppoll were introduced just after 2.6.16-rc1. Due to the way
the kernel versions are advertised we can only rely on 2.6.17 to have
the code. On x86_64 and SH this appeared first in 2.6.19-rc1,
on ia64 in 2.6.22-rc1. */
#if __LINUX_KERNEL_VERSION >= 0x020611 \
&& ((!defined __x86_64__ && !defined __sh__) \
|| (__LINUX_KERNEL_VERSION >= 0x020613 \
&& (defined __x86_64__ || defined __sh__)))
# define __ASSUME_PSELECT 1
# define __ASSUME_PPOLL 1
#endif
/* The *at syscalls were introduced just after 2.6.16-rc1. Due to the way the
kernel versions are advertised we can only rely on 2.6.17 to have
the code. On PPC they were introduced in 2.6.17-rc1,
on SH in 2.6.19-rc1. */
#if __LINUX_KERNEL_VERSION >= 0x020611 \
&& (!defined __sh__ || __LINUX_KERNEL_VERSION >= 0x020613)
# define __ASSUME_ATFCTS 1
#endif
/* Support for inter-process robust mutexes was added in 2.6.17. */
#if __LINUX_KERNEL_VERSION >= 0x020611 \
&& (!defined __sh__ || __LINUX_KERNEL_VERSION >= 0x020613)
# define __ASSUME_SET_ROBUST_LIST 1
#endif
/* Pessimistically assume that 2.6.18 introduced real handling of
large numbers of requests to readv and writev and that we don't
need a fallback. It likely worked for much longer. */
#if __LINUX_KERNEL_VERSION >= 0x020612
# define __ASSUME_COMPLETE_READV_WRITEV 1
#endif
/* Support for PI futexes was added in 2.6.18. */
#if __LINUX_KERNEL_VERSION >= 0x020612
# define __ASSUME_FUTEX_LOCK_PI 1
#endif
/* Support for utimensat syscall was added in 2.6.22, on SH
only after 2.6.22-rc1. */
#if __LINUX_KERNEL_VERSION >= 0x020616 \
&& (!defined __sh__ || __LINUX_KERNEL_VERSION >= 0x020617)
# define __ASSUME_UTIMENSAT 1
#endif
/* Support for private futexes was added in 2.6.22. */
#if __LINUX_KERNEL_VERSION >= 0x020616
# define __ASSUME_PRIVATE_FUTEX 1
#endif
/* Support for fallocate was added in 2.6.23, on s390
only after 2.6.23-rc1. */
#if __LINUX_KERNEL_VERSION >= 0x020617 \
&& (!defined __s390__ || __LINUX_KERNEL_VERSION >= 0x020618)
# define __ASSUME_FALLOCATE 1
#endif
/* Support for various CLOEXEC and NONBLOCK flags was added for x86,
x86-64, PPC, IA-64, SPARC< and S390 in 2.6.23. */
#if __LINUX_KERNEL_VERSION >= 0x020617 \
&& (defined __i386__ || defined __x86_64__ || defined __powerpc__ \
|| defined __sparc__ || defined __s390__)
# define __ASSUME_O_CLOEXEC 1
#endif
/* From 2.6.23 onwards the value of ARG_MAX depends on the stack
size. */
#define __LINUX_ARG_MAX_STACK_BASED_MIN_KERNEL 0x020617
#if __LINUX_KERNEL_VERSION >= __LINUX_ARG_MAX_STACK_BASED_MIN_KERNEL
# define __ASSUME_ARG_MAX_STACK_BASED 1
#endif
/* Support for ADJ_OFFSET_SS_READ was added in 2.6.24. */
#if __LINUX_KERNEL_VERSION >= 0x020618
# define __ASSUME_ADJ_OFFSET_SS_READ 1
#endif
/* Support for various CLOEXEC and NONBLOCK flags was added for x86,
x86-64, PPC, IA-64, and SPARC in 2.6.27. */
#if __LINUX_KERNEL_VERSION >= 0x02061b \
&& (defined __i386__ || defined __x86_64__ || defined __powerpc__ \
|| defined __sparc__ || defined __s390__)
# define __ASSUME_SOCK_CLOEXEC 1
# define __ASSUME_IN_NONBLOCK 1
# define __ASSUME_PIPE2 1
# define __ASSUME_EVENTFD2 1
# define __ASSUME_SIGNALFD4 1
# define __ASSUME_DUP3 1
#endif
/* Support for accept4 functionality was added in 2.6.28, but for some
architectures using a separate syscall rather than socketcall that
syscall was only added later, and some architectures first had
socketcall support then a separate syscall. Define
__ASSUME_ACCEPT4_SOCKETCALL if glibc uses socketcall on this
architecture and accept4 is available through socketcall,
__ASSUME_ACCEPT4_SYSCALL if it is available through a separate
syscall, __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL if it became
available through a separate syscall at the same time as through
socketcall, and __ASSUME_ACCEPT4 if the accept4 function is known
to work. */
#if __LINUX_KERNEL_VERSION >= 0x02061c && defined __ASSUME_SOCKETCALL
# define __ASSUME_ACCEPT4_SOCKETCALL 1
#endif
/* The accept4 syscall was added for x86_64 and SPARC in 2.6.28, and
for PowerPC and SH in 2.6.37. */
#if (__LINUX_KERNEL_VERSION >= 0x02061c \
&& (defined __x86_64__ || defined __sparc__)) \
|| (__LINUX_KERNEL_VERSION >= 0x020625 \
&& (defined __powerpc__ || defined __sh__))
# define __ASSUME_ACCEPT4_SYSCALL 1
#endif
#ifdef __sparc__
# define __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL 1
#endif
#if defined __ASSUME_ACCEPT4_SOCKETCALL || defined __ASSUME_ACCEPT4_SYSCALL
# define __ASSUME_ACCEPT4 1
#endif
/* Support for the FUTEX_CLOCK_REALTIME flag was added in 2.6.29. */
#if __LINUX_KERNEL_VERSION >= 0x02061d
# define __ASSUME_FUTEX_CLOCK_REALTIME 1
#endif
/* Support for the AT_RANDOM auxiliary vector entry was added in 2.6.29. */
#if __LINUX_KERNEL_VERSION >= 0x02061d
# define __ASSUME_AT_RANDOM 1
#endif
/* Support for preadv and pwritev was added in 2.6.30. */
#if __LINUX_KERNEL_VERSION >= 0x02061e
# define __ASSUME_PREADV 1
# define __ASSUME_PWRITEV 1
#endif
/* Support for FUTEX_*_REQUEUE_PI was added in 2.6.31. */
#if __LINUX_KERNEL_VERSION >= 0x02061f
# define __ASSUME_REQUEUE_PI 1
#endif
/* Support for F_GETOWN_EX was introduced in 2.6.32. */
#if __LINUX_KERNEL_VERSION >= 0x020620
# define __ASSUME_F_GETOWN_EX 1
#endif
/* Support for the recvmmsg syscall was added in 2.6.33. */
#if __LINUX_KERNEL_VERSION >= 0x020621
# define __ASSUME_RECVMMSG 1
#endif
/* Support for /proc/self/task/$tid/comm and /proc/$pid/task/$tid/comm was
added in 2.6.33. */
#if __LINUX_KERNEL_VERSION >= 0x020621
# define __ASSUME_PROC_PID_TASK_COMM 1
#endif
/* statfs fills in f_flags since 2.6.36. */
#if __LINUX_KERNEL_VERSION >= 0x020624
# define __ASSUME_STATFS_F_FLAGS 1
#endif
/* prlimit64 is available in 2.6.36. */
#if __LINUX_KERNEL_VERSION >= 0x020624
# define __ASSUME_PRLIMIT64 1
#endif
/* sendmmsg is available in 2.6.39. */
#if __LINUX_KERNEL_VERSION >= 0x020627
# define __ASSUME_SENDMMSG 1
#endif
/* getcpu is a syscall for x86-64 since 3.1. */
#if defined __x86_64__ && __LINUX_KERNEL_VERSION >= 0x030100
# define __ASSUME_GETCPU_SYSCALL 1
#endif
/* 2.6.29 removed the XFS restricted_chown sysctl, so it is pointless looking
for it in newer kernels. */
#if __LINUX_KERNEL_VERSION >= 0x02061d
# define __ASSUME_XFS_RESTRICTED_CHOWN 1
#endif
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