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.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" Copyright (C) 2003 Andi Kleen
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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2007-12-25 17:06:46 +00:00
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.TH ARCH_PRCTL 2 2007-12-26 "Linux" "Linux Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.SH NAME
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arch_prctl \- set architecture-specific thread state
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.SH SYNOPSIS
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.nf
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.B #include <asm/prctl.h>
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.br
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.B #include <sys/prctl.h>
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.sp
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.BI "int arch_prctl(int " code ", unsigned long " addr );
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.BI "int arch_prctl(int " code ", unsigned long *" addr );
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.fi
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.SH DESCRIPTION
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The
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.BR arch_prctl ()
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function sets architecture-specific process or thread state.
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.I code
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selects a subfunction
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and passes argument
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.I addr
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to it;
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.I addr
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is interpreted as either an
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.I "unsigned long"
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for the "set" operations, or as an
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.IR "unsigned long *" ,
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for the "get" operations.
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.LP
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Sub functions for x86-64 are:
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.TP
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.B ARCH_SET_FS
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Set the 64-bit base for the
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.I FS
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register to
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.IR addr .
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.TP
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.B ARCH_GET_FS
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Return the 64-bit base value for the
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.I FS
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register of the current thread in the
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.I unsigned long
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pointed to by
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.IR addr .
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.TP
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.B ARCH_SET_GS
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Set the 64-bit base for the
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.I GS
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register to
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.IR addr .
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.TP
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.B ARCH_GET_GS
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Return the 64-bit base value for the
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.I GS
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register of the current thread in the
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.I unsigned long
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pointed to by
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.IR addr .
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.SH RETURN VALUE
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On success,
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.BR arch_prctl ()
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returns 0; on error, \-1 is returned, and
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.I errno
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is set to indicate the error.
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.SH ERRORS
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.TP
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.B EFAULT
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.I addr
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points to an unmapped address or is outside the process address space.
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.TP
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.B EINVAL
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.I code
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is not a valid subcommand.
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.TP
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.B EPERM
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.I addr
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is outside the process address space.
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.\" .SH AUTHOR
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.\" Man page written by Andi Kleen.
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.SH "CONFORMING TO"
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.BR arch_prctl ()
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is a Linux/x86-64 extension and should not be used in programs intended
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to be portable.
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.SH NOTES
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.BR arch_prctl ()
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is only supported on Linux/x86-64 for 64-bit programs currently.
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2007-06-25 09:55:58 +00:00
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The 64-bit base changes when a new 32-bit segment selector is loaded.
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.B ARCH_SET_GS
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is disabled in some kernels.
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2007-06-25 09:55:58 +00:00
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Context switches for 64-bit segment bases are rather expensive.
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It may be a faster alternative to set a 32-bit base using a
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segment selector by setting up an LDT with
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.BR modify_ldt (2)
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or using the
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.BR set_thread_area (2)
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system call in kernel 2.5 or later.
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.BR arch_prctl ()
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is only needed when you want to set bases that are larger than 4GB.
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Memory in the first 2GB of address space can be allocated by using
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.BR mmap (2)
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with the
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.B MAP_32BIT
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flag.
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2007-12-25 17:06:46 +00:00
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As of version 2.7, glibc provides no prototype for
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2005-11-03 14:14:09 +00:00
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.BR arch_prctl ().
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You have to declare it yourself for now.
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This may be fixed in future glibc versions.
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.I FS
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may be already used by the threading library.
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.SH "SEE ALSO"
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.BR mmap (2),
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.BR modify_ldt (2),
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.BR prctl (2),
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.BR set_thread_area (2)
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arch_prctl.2, fcntl.2, flock.2, get_robust_list.2, getpriority.2, ioprio_set.2, migrate_pages.2, mmap.2, mremap.2, msync.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, select.2, socket.2, subpage_prot.2, unshare.2, btree.3, dbopen.3, dl_iterate_phdr.3, dlopen.3, getnameinfo.3, hash.3, lockf.3, netlink.3, recno.3, rpc.3, xdr.3, cciss.4, console_ioctl.4, hpsa.4, initrd.4, msr.4, rtc.4, st.4, hosts.5, services.5, tzfile.5, aio.7, arp.7, capabilities.7, cpuset.7, feature_test_macros.7, futex.7, inotify.7, ip.7, ipv6.7, iso_8859-16.7, iso_8859-2.7, koi8-r.7, math_error.7, netlink.7, packet.7, pthreads.7, raw.7, spufs.7, udplite.7, uri.7, x25.7: Global fix: Various consistency fixes for SEE ALSO
Coauthored-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-09-24 07:53:22 +00:00
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2004-11-03 13:51:07 +00:00
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AMD X86-64 Programmer's manual
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