2006-02-21 03:12:56 +01:00
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/* Set flags signalling availability of kernel features based on given
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kernel version number.
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2016-01-04 17:05:18 +01:00
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Copyright (C) 1999-2016 Free Software Foundation, Inc.
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2006-02-21 03:12:56 +01:00
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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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2012-03-10 00:56:38 +01:00
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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2006-02-21 03:12:56 +01:00
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#include <sgidefs.h>
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2010-08-14 01:43:22 +02:00
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#include_next <kernel-features.h>
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Correct robust mutex / PI futex kernel assumptions (bug 9894).
This patch continues fixing __ASSUME_* issues in preparation for
moving to a 2.6.32 minimum kernel version by addressing assumptions on
robust mutex and PI futex support availability. Those assumptions are
bug 9894, but to be clear this patch does not address all the issues
from that bug about wrong version assumptions, only those still
applicable for --enable-kernel=2.6.32 or later (with the expectation
that the move to that minimum kernel will obsolete the other parts of
the bug). The patch is independent of
<https://sourceware.org/ml/libc-alpha/2014-03/msg00585.html>, my other
pending-review patch preparing for the kernel version change; the two
together complete all the changes I believe are needed in preparation
regarding any macro in sysdeps/unix/sysv/linux/kernel-features.h that
would be affected by such a change. (I have not checked the
correctness of macros whose conditions are unaffected by such a
change, or macros only defined in other kernel-features.h files.)
As discussed in that bug, robust mutexes and PI futexes need
futex_atomic_cmpxchg_inatomic to be implemented, in addition to
certain syscalls needed for robust mutexes (and
architecture-independent kernel pieces for all the features in
question). That is, as I understand it, they need
futex_atomic_cmpxchg_inatomic to *work* (not return an ENOSYS error).
The issues identified in my analysis relate to ARM, M68K, MicroBlaze,
MIPS and SPARC.
On ARM, whether futex_atomic_cmpxchg_inatomic works depends on the
kernel configuration. As of 3.13, the condition for *not* working is
CONFIG_CPU_USE_DOMAINS && CONFIG_SMP. As of 2.6.32 it was simply
CONFIG_SMP that meant the feature was not implemented. I don't know
if there are any circumstances in which we can say "we can assume a
userspace glibc binary built with these options will never run on a
kernel with the problematic configuration", but at least for now I'm
just undefining the relevant __ASSUME_* macros for ARM.
On M68K, two of the three macros are undefined for kernels before
3.10, but as far as I can see __ASSUME_FUTEX_LOCK_PI is in the same
group needing futex_atomic_cmpxchg_inatomic support and so should be
undefined as well.
On MicroBlaze the required support was added in 2.6.33.
On MIPS, the support depends on cpu_has_llsc in the kernel - that is,
actual hardware LL/SC support (GCC and glibc for MIPS GNU/Linux rely
on the instructions being supported in some way, but it may be kernel
emulation; futex_atomic_cmpxchg_inatomic doesn't work with that
emulation). The same condition as in GCC for indicating LL/SC support
may not be available is used for undefining the macros in glibc,
__mips == 1 || defined _MIPS_ARCH_R5900. (Maybe we could in fact
desupport MIPS processors without the hardware support in glibc.)
On SPARC, 32-bit kernels don't support futex_atomic_cmpxchg_inatomic;
__arch64__ || __sparc_v9__ is used as the condition for binaries that
won't run on 32-bit kernels.
This patch is not tested beyond the sanity check of an x86_64 build.
[BZ #9894]
* sysdeps/unix/sysv/linux/kernel-features.h
[__sparc__ && !__arch64__ && !__sparc_v9__]
(__ASSUME_SET_ROBUST_LIST): Do not define.
[__sparc__ && !__arch64__ && !__sparc_v9__]
(__ASSUME_FUTEX_LOCK_PI): Likewise.
[__sparc__ && !__arch64__ && !__sparc_v9__] (__ASSUME_REQUEUE_PI):
Likewise.
* sysdeps/unix/sysv/linux/arm/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Undefine.
(__ASSUME_REQUEUE_PI): Likewise.
(__ASSUME_SET_ROBUST_LIST): Likewise.
* sysdeps/unix/sysv/linux/m68k/kernel-features.h
[__LINUX_KERNEL_VERSION < 0x030a00] (__ASSUME_FUTEX_LOCK_PI):
Undefine.
* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
[__LINUX_KERNEL_VERSION < 0x020621] (__ASSUME_FUTEX_LOCK_PI):
Likewise.
[__LINUX_KERNEL_VERSION < 0x020621] (__ASSUME_REQUEUE_PI):
Likewise.
[__LINUX_KERNEL_VERSION < 0x020621] (__ASSUME_SET_ROBUST_LIST):
Likewise.
* sysdeps/unix/sysv/linux/mips/kernel-features.h
[__mips == 1 || _MIPS_ARCH_R5900] (__ASSUME_FUTEX_LOCK_PI):
Undefine.
[__mips == 1 || _MIPS_ARCH_R5900] (__ASSUME_REQUEUE_PI): Likewise.
[__mips == 1 || _MIPS_ARCH_R5900] (__ASSUME_SET_ROBUST_LIST):
Likewise.
2014-03-31 14:55:18 +02:00
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/* The MIPS kernel does not support futex_atomic_cmpxchg_inatomic if
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emulating LL/SC. */
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#if __mips == 1 || defined _MIPS_ARCH_R5900
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# undef __ASSUME_REQUEUE_PI
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# undef __ASSUME_SET_ROBUST_LIST
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#endif
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2015-11-17 21:19:06 +01:00
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/* Define this if your 32-bit syscall API requires 64-bit register
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pairs to start with an even-number register. */
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#if _MIPS_SIM == _ABIO32
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# define __ASSUME_ALIGNED_REGISTER_PAIRS 1
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Add __ASSUME_DIRECT_SYSVIPC_SYSCALL for Linux
On current minimum supported kernels, the SysV IPC on Linux is provided
by either the ipc syscalls or correspondent wire syscalls. Also, for
architectures that supports wire syscalls all syscalls are supported
in a set (msgct, msgrcv, msgsnd, msgget, semctl, semget, semop, semtimedop,
shmctl, shmat, shmget, shmdt).
The architectures that only supports ipc syscall are:
- i386, m68k, microblaze, mips32, powerpc (powerpc32, powerpc64, and
powerpc64le), s390 (32 and 64 bits), sh, sparc32, and sparc64.
And the architectures that only supports wired syscalls are:
- aarch64, alpha, hppa, ia64, mips64, mips64n32, nios2, tile
(tilepro, tilegx, and tilegx64), and x86_64
Also arm is the only one that supports both wire syscalls and the
ipc, although the ipc one is deprecated.
This patch adds a new define, __ASSUME_DIRECT_SYSVIPC_SYSCALL, that wired
syscalls are supported on the system and the general idea is to use
it where possible.
I also checked the syscall table for all architectures on Linux 4.9
and there is no change on described support for Linux 2.6.32/3.2.
* sysdeps/unix/sysv/linux/kernel-features.h
(__ASSUME_DIRECT_SYSVIPC_SYSCALL): New define.
* sysdeps/unix/sysv/linux/i386/kernel-features.h
(__ASSUME_DIRECT_SYSVIPC_SYSCALL): Undef.
* sysdeps/unix/sysv/linux/m68k/kernel-features.h
(__ASSUME_DIRECT_SYSVIPC_SYSCALL): Likewise.
* sysdeps/unix/sysv/linux/mips/kernel-features.h
(__ASSUME_DIRECT_SYSVIPC_SYSCALL): Likewise.
* sysdeps/unix/sysv/linux/powerpc/kernel-features.h
(__ASSUME_DIRECT_SYSVIPC_SYSCALL): Likewise.
* sysdeps/unix/sysv/linux/s390/kernel-features.h
(__ASSUME_DIRECT_SYSVIPC_SYSCALL): Likewise.
* sysdeps/unix/sysv/linux/sh/kernel-features.h
(__ASSUME_DIRECT_SYSVIPC_SYSCALL): Likewise.
* sysdeps/unix/sysv/linux/sparc/kernel-features.h
(__ASSUME_DIRECT_SYSVIPC_SYSCALL): Likewise.
2016-11-02 18:41:15 +01:00
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/* mips32 only supports ipc syscall. */
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# undef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
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2015-11-17 21:19:06 +01:00
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#endif
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Consolidate off_t/off64_t syscall argument passing
This patch add three new macros (SYSCALL_LL, SYSCALL_LL64, and
__ASSUME_WORDSIZE64_ILP32) to use along with off_t and off64_t argument
syscalls. The rationale for this change is:
1. Remove multiple implementations for the same syscall for different
architectures (for instance, pread have 6 different implementations).
2. Also remove the requirement to use syscall wrappers for cancellable
entrypoints.
The macro usage should be used along __ALIGNMENT_ARG to follow ABI constrains
for architecture where it applies. For instance, pread can be rewritten as:
return SYSCALL_CANCEL (pread, fd, buf, count,
__ALIGNMENT_ARG SYSCALL_LL (offset));
Another macro, SYSCALL_LL64, is provided for off64_t. The macro
__ASSUME_WORDSIZE64_ILP32 is used by the ABI to define is uses 64-bit register
even if ABI is ILP32 (for instance x32 and mips64-n32).
The changes itself are not currently used in any implementation, so no
code change is expected.
* sysdeps/unix/sysv/linux/generic/sysdep.h (__ALIGNMENT_ARG): Move
definition.
(__ALIGNMENT_COUNT): Likewise.
* sysdeps/unix/sysv/linux/sysdep.h (__ALIGNMENT_ARG): To here.
(__ALIGNMENT_COUNT): Likewise.
(SYSCALL_LL): New define.
(SYSCALL_LL64): Likewise.
* sysdeps/unix/sysv/linux/mips/kernel-features.h:
[_MIPS_SIM == _ABIO32] (__ASSUME_WORDSIZE64_ILP32): Define.
* sysdeps/unix/sysv/linux/x86_64/kernel-features.h:
[ILP32] (__ASUME_WORDSIZE64_ILP32): Likewise.
2015-10-21 14:04:07 +02:00
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/* Define that mips64-n32 is a ILP32 ABI to set the correct interface to
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pass 64-bits values through syscalls. */
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#if _MIPS_SIM == _ABIN32
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# define __ASSUME_WORDSIZE64_ILP32 1
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#endif
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