-.\" Hey Emacs! This file is -*- nroff -*- source.
-.\"
.\" Copyright (C) 1998 Andries Brouwer (aeb@cwi.nl)
-.\" and Copyright (C) 2002 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2002, 2006, 2008, 2012, 2013 Michael Kerrisk <mtk.manpages@gmail.com>
.\" and Copyright Guillem Jover <guillem@hadrons.org>
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
.\" Modified Thu Nov 11 04:19:42 MET 1999, aeb: added PR_GET_PDEATHSIG
.\" Modified 27 Jun 02, Michael Kerrisk
.\" 2012-04 Cyrill Gorcunov, Document PR_SET_MM
.\" 2012-04-25 Michael Kerrisk, Document PR_TASK_PERF_EVENTS_DISABLE and
.\" PR_TASK_PERF_EVENTS_ENABLE
+.\" 2012-09-20 Kees Cook, update PR_SET_SECCOMP for mode 2
+.\" 2012-09-20 Kees Cook, document PR_SET_NO_NEW_PRIVS, PR_GET_NO_NEW_PRIVS
+.\" 2012-10-25 Michael Kerrisk, Document PR_SET_TIMERSLACK and
+.\" PR_GET_TIMERSLACK
+.\" 2013-01-10 Kees Cook, document PR_SET_PTRACER
+.\" 2012-02-04 Michael kerrisk, document PR_{SET,GET}_CHILD_SUBREAPER
.\"
-.\" FIXME: Document PR_SET_TIMERSLACK and PR_GET_TIMERSLACK (new in 2.6.28)
-.\" commit 6976675d94042fbd446231d1bd8b7de71a980ada
.\"
-.TH PRCTL 2 2012-04-23 "Linux" "Linux Programmer's Manual"
+.TH PRCTL 2 2014-04-14 "Linux" "Linux Programmer's Manual"
.SH NAME
prctl \- operations on a process
.SH SYNOPSIS
if file capabilities are not enabled in the kernel,
in which case bounding sets are not supported.
.TP
+.BR PR_SET_CHILD_SUBREAPER " (since Linux 3.4)"
+.\" commit ebec18a6d3aa1e7d84aab16225e87fd25170ec2b
+If
+.I arg2
+is nonzero,
+set the "child subreaper" attribute of the calling process;
+if
+.I arg2
+is zero, unset the attribute.
+When a process is marked as a child subreaper,
+all of the children that it creates, and their descendants,
+will be marked as having a subreaper.
+In effect, a subreaper fulfills the role of
+.BR init (1)
+for its descendant processes.
+Upon termination of a process
+that is orphaned (i.e., its immediate parent has already terminated)
+and marked as having a subreaper,
+the nearest still living ancestor subreaper
+will receive a
+.BR SIGCHLD
+signal and be able to
+.BR wait (2)
+on the process to discover its termination status.
+.TP
+.BR PR_GET_CHILD_SUBREAPER " (since Linux 3.4)"
+Return the "child subreaper" setting of the caller,
+in the location pointed to by
+.IR "(int\ *) arg2" .
+.TP
.BR PR_SET_DUMPABLE " (since Linux 2.3.20)"
Set the state of the flag determining whether core dumps are produced
-for this process upon delivery of a signal whose default behavior is
+for the calling process upon delivery of a signal whose default behavior is
to produce a core dump.
-(Normally this flag is set for a process by default, but it is cleared
+(Normally, this flag is set for a process by default, but it is cleared
when a set-user-ID or set-group-ID program is executed and also by
various system calls that manipulate process UIDs and GIDs).
In kernels up to and including 2.6.12,
in
.BR proc (5).)
Processes that are not dumpable can not be attached via
-.BR ptrace(2)
+.BR ptrace (2)
.BR PTRACE_ATTACH .
.TP
.BR PR_GET_DUMPABLE " (since Linux 2.3.20)"
"keep capabilities" flag.
.TP
.BR PR_SET_NAME " (since Linux 2.6.9)"
-Set the process name for the calling process,
+Set the name of the calling thread,
using the value in the location pointed to by
.IR "(char\ *) arg2" .
The name can be up to 16 bytes long,
.\" TASK_COMM_LEN in include/linux/sched.h
and should be null-terminated if it contains fewer bytes.
+This is the same attribute that can be set via
+.BR pthread_setname_np (3)
+and retrieved using
+.BR pthread_getname_np (3).
+The attribute is likewise accessible via
+.IR /proc/self/task/[tid]/comm ,
+where
+.I tid
+is the name of the calling thread.
.TP
.BR PR_GET_NAME " (since Linux 2.6.11)"
-Return the process name for the calling process,
+Return the name of the calling thread,
in the buffer pointed to by
.IR "(char\ *) arg2" .
The buffer should allow space for up to 16 bytes;
the returned string will be null-terminated if it is shorter than that.
.TP
+.BR PR_SET_NO_NEW_PRIVS " (since Linux 3.5)"
+Set the calling process's
+.I no_new_privs
+bit to the value in
+.IR arg2 .
+With
+.I no_new_privs
+set to 1,
+.BR execve (2)
+promises not to grant privileges to do anything
+that could not have been done without the
+.BR execve (2)
+call (for example,
+rendering the set-user-ID and set-group-ID permission bits,
+and file capabilities non-functional).
+Once set, this bit cannot be unset.
+The setting of this bit is inherited by children created by
+.BR fork (2)
+and
+.BR clone (2),
+and preserved across
+.BR execve (2).
+
+For more information, see the kernel source file
+.IR Documentation/prctl/no_new_privs.txt .
+.TP
+.BR PR_GET_NO_NEW_PRIVS " (since Linux 3.5)"
+Return (as the function result) the value of the
+.I no_new_privs
+bit for the current process.
+A value of 0 indicates the regular
+.BR execve (2)
+behavior.
+A value of 1 indicates
+.BR execve (2)
+will operate in the privilege-restricting mode described above.
+.TP
.BR PR_SET_PDEATHSIG " (since Linux 2.1.57)"
Set the parent process death signal
of the calling process to \fIarg2\fP (either a signal value
parent dies.
This value is cleared for the child of a
.BR fork (2)
-and (since Linux 2.5.36 / 2.6.23)
-when executing a set-user_ID or set-group-ID binary.
+and (since Linux 2.4.36 / 2.6.23)
+when executing a set-user-ID or set-group-ID binary.
+This value is preserved across
+.BR execve (2).
.TP
.BR PR_GET_PDEATHSIG " (since Linux 2.3.15)"
Return the current value of the parent process death signal,
in the location pointed to by
.IR "(int\ *) arg2" .
.TP
+.BR PR_SET_PTRACER " (since Linux 3.4)"
+.\" commit 2d514487faf188938a4ee4fb3464eeecfbdcf8eb
+.\" commit bf06189e4d14641c0148bea16e9dd24943862215
+This is meaningful only when the Yama LSM is enabled and in mode 1
+("restricted ptrace", visible via
+.IR /proc/sys/kernel/yama/ptrace_scope ).
+When a "ptracer process ID" is passed in \fIarg2\fP,
+the caller is declaring that the ptracer process can
+.BR ptrace (2)
+the calling process as if it were a direct process ancestor.
+Each
+.B PR_SET_PTRACER
+operation replaces the previous "ptracer process ID".
+Employing
+.B PR_SET_PTRACER
+with
+.I arg2
+set to 0 clears the caller's "ptracer process ID".
+If
+.I arg2
+is
+.BR PR_SET_PTRACER_ANY ,
+the ptrace restrictions introduced by Yama are effectively disabled for the
+calling process.
+
+For further information, see the kernel source file
+.IR Documentation/security/Yama.txt .
+.TP
.BR PR_SET_SECCOMP " (since Linux 2.6.23)"
.\" See http://thread.gmane.org/gmane.linux.kernel/542632
.\" [PATCH 0 of 2] seccomp updates
.\" andrea@cpushare.com
-Set the secure computing mode for the calling thread.
-In the current implementation,
+Set the secure computing (seccomp) mode for the calling thread, to limit
+the available system calls.
+The seccomp mode is selected via
+.IR arg2 .
+(The seccomp constants are defined in
+.IR <linux/seccomp.h> .)
+
+With
.IR arg2
-must be 1.
-After the secure computing mode has been set to 1,
+set to
+.BR SECCOMP_MODE_STRICT
the only system calls that the thread is permitted to make are
.BR read (2),
.BR write (2),
Other system calls result in the delivery of a
.BR SIGKILL
signal.
-Secure computing mode is useful for number-crunching applications
+Strict secure computing mode is useful for number-crunching applications
that may need to execute untrusted byte code,
perhaps obtained by reading from a pipe or socket.
-This operation is only available
-if the kernel is configured with CONFIG_SECCOMP enabled.
+This operation is available only
+if the kernel is configured with
+.B CONFIG_SECCOMP
+enabled.
+
+With
+.IR arg2
+set to
+.BR SECCOMP_MODE_FILTER " (since Linux 3.5)"
+the system calls allowed are defined by a pointer
+to a Berkeley Packet Filter passed in
+.IR arg3 .
+This argument is a pointer to
+.IR "struct sock_fprog" ;
+it can be designed to filter
+arbitrary system calls and system call arguments.
+This mode is available only if the kernel is configured with
+.B CONFIG_SECCOMP_FILTER
+enabled.
+
+If
+.BR SECCOMP_MODE_FILTER
+filters permit
+.BR fork (2),
+then the seccomp mode is inherited by children created by
+.BR fork (2);
+if
+.BR execve (2)
+is permitted, then the seccomp mode is preserved across
+.BR execve (2).
+If the filters permit
+.BR prctl ()
+calls, then additional filters can be added;
+they are run in order until the first non-allow result is seen.
+
+For further information, see the kernel source file
+.IR Documentation/prctl/seccomp_filter.txt .
.TP
.BR PR_GET_SECCOMP " (since Linux 2.6.23)"
-Return the secure computing mode of the calling thread.
-Not very useful for the current implementation (mode equals 1),
-but may be useful for other possible future modes:
-if the caller is not in secure computing mode, this operation returns 0;
-if the caller is in secure computing mode, then the
+Return (as the function result)
+the secure computing mode of the calling thread.
+If the caller is not in secure computing mode, this operation returns 0;
+if the caller is in strict secure computing mode, then the
.BR prctl ()
call will cause a
.B SIGKILL
signal to be sent to the process.
-This operation is only available
-if the kernel is configured with CONFIG_SECCOMP enabled.
+If the caller is in filter mode, and this system call is allowed by the
+seccomp filters, it returns 2.
+This operation is available only
+if the kernel is configured with
+.B CONFIG_SECCOMP
+enabled.
.TP
.BR PR_SET_SECUREBITS " (since Linux 2.6.26)"
Set the "securebits" flags of the calling thread to the value supplied in
See
.BR capabilities (7).
.TP
+.BR PR_SET_THP_DISABLE " (since Linux 3.15)"
+.\" commit a0715cc22601e8830ace98366c0c2bd8da52af52
+Set the state of the "THP disable" flag for the calling thread.
+If
+.I arg2
+has a nonzero value, the flag is set, otherwise it is cleared.
+Setting this flag provides a method
+for disabling transparent huge pages
+for jobs where the code cannot be modified, and using a malloc hook with
+.BR madvise (2)
+is not an option (i.e., statically allocated data).
+The setting of the "THP disable" flag is inherited by a child created via
+.BR fork (2)
+and is preserved across
+.BR execve (2).
+.TP
+.BR PR_GET_THP_DISABLE " (since Linux 3.15)"
+Return (via the function result) the current setting of the "THP disable"
+flag for the calling thread:
+either 1, if the flag is set, or 0, if it is not.
+.TP
+.BR PR_GET_TID_ADDRESS " (since Linux 3.5)"
+.\" commit 300f786b2683f8bb1ec0afb6e1851183a479c86d
+Retrieve the
+.I clear_child_tid
+address set by
+.BR set_tid_address (2)
+and the
+.BR clone (2)
+.B CLONE_CHILD_CLEARTID
+flag, in the location pointed to by
+.IR "(int\ **)\ arg2" .
+This feature is available only if the kernel is built with the
+.BR CONFIG_CHECKPOINT_RESTORE
+option enabled.
+.TP
+.BR PR_SET_TIMERSLACK " (since Linux 2.6.28)"
+.\" See https://lwn.net/Articles/369549/
+.\" commit 6976675d94042fbd446231d1bd8b7de71a980ada
+Set the current timer slack for the calling thread to the nanosecond value
+supplied in
+.IR arg2 .
+If
+.I arg2
+is less than or equal to zero,
+.\" It seems that it's not possible to set the timer slack to zero;
+.\" The minimum value is 1? Seems a little strange.
+reset the current timer slack to the thread's default timer slack value.
+The timer slack is used by the kernel to group timer expirations
+for the calling thread that are close to one another;
+as a consequence, timer expirations for the thread may be
+up to the specified number of nanoseconds late (but will never expire early).
+Grouping timer expirations can help reduce system power consumption
+by minimizing CPU wake-ups.
+
+The timer expirations affected by timer slack are those set by
+.BR select (2),
+.BR pselect (2),
+.BR poll (2),
+.BR ppoll (2),
+.BR epoll_wait (2),
+.BR epoll_pwait (2),
+.BR clock_nanosleep (2),
+.BR nanosleep (2),
+and
+.BR futex (2)
+(and thus the library functions implemented via futexes, including
+.\" List obtained by grepping for futex usage in glibc source
+.BR pthread_cond_timedwait (3),
+.BR pthread_mutex_timedlock (3),
+.BR pthread_rwlock_timedrdlock (3),
+.BR pthread_rwlock_timedwrlock (3),
+and
+.BR sem_timedwait (3)).
+
+Timer slack is not applied to threads that are scheduled under
+a real-time scheduling policy (see
+.BR sched_setscheduler (2)).
+
+Each thread has two associated timer slack values:
+a "default" value, and a "current" value.
+The current value is the one that governs grouping
+of timer expirations.
+When a new thread is created,
+the two timer slack values are made the same as the current value
+of the creating thread.
+Thereafter, a thread can adjust its current timer slack value via
+.BR PR_SET_TIMERSLACK
+(the default value can't be changed).
+The timer slack values of
+.IR init
+(PID 1), the ancestor of all processes,
+are 50,000 nanoseconds (50 microseconds).
+The timer slack values are preserved across
+.BR execve (2).
+.TP
+.BR PR_GET_TIMERSLACK " (since Linux 2.6.28)"
+Return (as the function result)
+the current timer slack value of the calling thread.
+.TP
.BR PR_SET_TIMING " (since Linux 2.6.0-test4)"
Set whether to use (normal, traditional) statistical process timing or
accurate timestamp-based process timing, by passing
this process or another process.
Performance counters created by the calling process for other
processes are unaffected.
-For more information on performance counters, see the kernel source file
+For more information on performance counters, see the Linux kernel source file
.IR tools/perf/design.txt .
.IP
Originally called
.B SIGBUS
signal as soon as hardware memory corruption is detected inside
its address space.
-In late kill mode, the process is only killed when it accesses a corrupted page.
+In late kill mode, the process is killed only when it accesses a corrupted page.
See
.BR sigaction (2)
for more information on the
arguments must be zero.
.TP
.BR PR_SET_MM " (since Linux 3.3)"
+.\" commit 028ee4be34a09a6d48bdf30ab991ae933a7bc036
Modify certain kernel memory map descriptor fields
of the calling process.
Usually these fields are set by the kernel and dynamic loader (see
The requirements for the address are the same as for the
.BR PR_SET_MM_START_BRK
option.
-.\" FIXME The following (until ========) is not yet in mainline kernel,
-.\" so commented out for the moment.
-.\" .TP
-.\" .BR PR_SET_MM_ARG_START
-.\" Set the address above which the program command line is placed.
-.\" .TP
-.\" .BR PR_SET_MM_ARG_END
-.\" Set the address below which the program command line is placed.
-.\" .TP
-.\" .BR PR_SET_MM_ENV_START
-.\" Set the address above which the program environment is placed.
-.\" .TP
-.\" .BR PR_SET_MM_ENV_END
-.\" Set the address below which the program environment is placed.
-.\" .IP
-.\" The address passed with
-.\" .BR PR_SET_MM_ARG_START ,
-.\" .BR PR_SET_MM_ARG_END ,
-.\" .BR PR_SET_MM_ENV_START ,
-.\" and
-.\" .BR PR_SET_MM_ENV_END
-.\" should belong to a process stack area.
-.\" Thus, the corresponding memory area must be readable, writable, and
-.\" (depending on the kernel configuration) have the
-.\" .BR MAP_GROWSDOWN
-.\" attribute set (see
-.\" .BR mmap (2)).
-.\" .TP
-.\" .BR PR_SET_MM_AUXV
-.\" Set a new auxiliary vector.
-.\" The
-.\" .I arg3
-.\" argument should provide the address of the vector.
-.\" The
-.\" .I arg4
-.\" is the size of the vector.
-.\" .TP
-.\" .BR PR_SET_MM_EXE_FILE
-.\" Supersede the
-.\" .IR /proc/pid/exe
-.\" symbolic link with a new one pointing to a new executable file
-.\" identified by the file descriptor provided in
-.\" .I arg3
-.\" argument.
-.\" The file descriptor should be obtained with a regular
-.\" .BR open (2)
-.\" call.
-.\" .IP
-.\" To change the symbolic link, one needs to unmap all existing
-.\" executable memory areas, including those created by the kernel itself
-.\" (for example the kernel usually creates at least one executable
-.\" memory area for the ELF
-.\" .IR \.text
-.\" section).
-.\" .IP
-.\" The second limitation is that such transitions can be done only once
-.\" in a process life time.
-.\" Any further attempts will be rejected.
-.\" This should help system administrators to monitor unusual
-.\" symbolic-link transitions over all process running in a system.
-.\" ========== END FIXME
+.P
+The following options are available since Linux 3.5.
+.\" commit fe8c7f5cbf91124987106faa3bdf0c8b955c4cf7
+.TP
+.BR PR_SET_MM_ARG_START
+Set the address above which the program command line is placed.
+.TP
+.BR PR_SET_MM_ARG_END
+Set the address below which the program command line is placed.
+.TP
+.BR PR_SET_MM_ENV_START
+Set the address above which the program environment is placed.
+.TP
+.BR PR_SET_MM_ENV_END
+Set the address below which the program environment is placed.
+.IP
+The address passed with
+.BR PR_SET_MM_ARG_START ,
+.BR PR_SET_MM_ARG_END ,
+.BR PR_SET_MM_ENV_START ,
+and
+.BR PR_SET_MM_ENV_END
+should belong to a process stack area.
+Thus, the corresponding memory area must be readable, writable, and
+(depending on the kernel configuration) have the
+.BR MAP_GROWSDOWN
+attribute set (see
+.BR mmap (2)).
+.TP
+.BR PR_SET_MM_AUXV
+Set a new auxiliary vector.
+The
+.I arg3
+argument should provide the address of the vector.
+The
+.I arg4
+is the size of the vector.
+.TP
+.BR PR_SET_MM_EXE_FILE
+.\" commit b32dfe377102ce668775f8b6b1461f7ad428f8b6
+Supersede the
+.IR /proc/pid/exe
+symbolic link with a new one pointing to a new executable file
+identified by the file descriptor provided in
+.I arg3
+argument.
+The file descriptor should be obtained with a regular
+.BR open (2)
+call.
+.IP
+To change the symbolic link, one needs to unmap all existing
+executable memory areas, including those created by the kernel itself
+(for example the kernel usually creates at least one executable
+memory area for the ELF
+.IR \.text
+section).
+.IP
+The second limitation is that such transitions can be done only once
+in a process life time.
+Any further attempts will be rejected.
+This should help system administrators monitor unusual
+symbolic-link transitions over all processes running on a system.
.RE
.\"
-.SH "RETURN VALUE"
+.SH RETURN VALUE
On success,
.BR PR_GET_DUMPABLE ,
.BR PR_GET_KEEPCAPS ,
+.BR PR_GET_NO_NEW_PRIVS ,
+.BR PR_GET_THP_DISABLE ,
.BR PR_CAPBSET_READ ,
.BR PR_GET_TIMING ,
+.BR PR_GET_TIMERSLACK ,
.BR PR_GET_SECUREBITS ,
.BR PR_MCE_KILL_GET ,
and (if it returns)
is
.BR PR_SET_SECCOMP
or
-.BR PR_SET_SECCOMP ,
+.BR PR_GET_SECCOMP ,
and the kernel was not configured with
.BR CONFIG_SECCOMP .
.TP
.BR PR_SET_MM_START_DATA ,
.BR PR_SET_MM_END_DATA ,
or
-.BR PR_SET_MM_START_STACK,
+.BR PR_SET_MM_START_STACK ,
and the permissions of the corresponding memory area are not as required;
.IP *
.I arg2
resource limit to be exceeded.
.RE
.TP
+.B EINVAL
+.I option
+is
+.BR PR_SET_PTRACER
+and
+.I arg2
+is not 0,
+.BR PR_SET_PTRACER_ANY ,
+or the PID of an existing process.
+.TP
+.B EINVAL
+.I option
+is
+.B PR_SET_PDEATHSIG
+and
+.I arg2
+is not a valid signal number.
+.TP
+.B EINVAL
+.I option
+is
+.BR PR_SET_DUMPABLE
+and
+.I arg2
+is neither
+.B SUID_DUMP_DISABLE
+nor
+.BR SUID_DUMP_USER .
+.TP
+.B EINVAL
+.I option
+is
+.BR PR_SET_TIMING
+and
+.I arg2
+is not
+.BR PR_TIMING_STATISTICAL .
+.TP
+.B EINVAL
+.I option
+is
+.BR PR_SET_NO_NEW_PRIVS
+and
+.I arg2
+is not equal to 1
+or
+.IR arg3 ,
+.IR arg4 ,
+or
+.IR arg5
+is nonzero.
+.TP
+.B EINVAL
+.I option
+is
+.BR PR_GET_NO_NEW_PRIVS
+and
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+or
+.IR arg5
+is nonzero.
+.TP
+.B EINVAL
+.I option
+is PR_SET_THP_DISABLE
+and
+.IR arg3 ,
+.IR arg4 ,
+or
+.IR arg5
+is nonzero.
+.TP
+.B EINVAL
+.I option
+is PR_GET_THP_DISABLE
+and
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+or
+.IR arg5
+is nonzero.
+.TP
.B EPERM
.I option
is
and the caller does not have the
.B CAP_SYS_RESOURCE
capability.
-.\" FIXME The following (until ========) is not yet in mainline kernel,
-.\" so commented out for the moment.
-.\" .TP
-.\" .B EACCES
-.\" .I option
-.\" is
-.\" .BR PR_SET_MM ,
-.\" and
-.\" .I arg3
-.\" is
-.\" .BR PR_SET_MM_EXE_FILE ,
-.\" the file is not executable.
-.\" .TP
-.\" .B EBUSY
-.\" .I option
-.\" is
-.\" .BR PR_SET_MM ,
-.\" .I arg3
-.\" is
-.\" .BR PR_SET_MM_EXE_FILE ,
-.\" and this the second attempt to change the
-.\" .I /proc/pid/exe
-.\" symbolic link, which is prohibited.
-.\" .TP
-.\" .B EBADF
-.\" .I option
-.\" is
-.\" .BR PR_SET_MM ,
-.\" .I arg3
-.\" is
-.\" .BR PR_SET_MM_EXE_FILE ,
-.\" and the file descriptor passed in
-.\" .I arg4
-.\" is not valid.
-.\" ========== END FIXME
+.TP
+.B EACCES
+.I option
+is
+.BR PR_SET_MM ,
+and
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+the file is not executable.
+.TP
+.B EBUSY
+.I option
+is
+.BR PR_SET_MM ,
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+and this the second attempt to change the
+.I /proc/pid/exe
+symbolic link, which is prohibited.
+.TP
+.B EBADF
+.I option
+is
+.BR PR_SET_MM ,
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+and the file descriptor passed in
+.I arg4
+is not valid.
.\" The following can't actually happen, because prctl() in
.\" seccomp mode will cause SIGKILL.
.\" .TP
.BR prctl ()
system call was introduced in Linux 2.1.57.
.\" The library interface was added in glibc 2.0.6
-.SH "CONFORMING TO"
+.SH CONFORMING TO
This call is Linux-specific.
IRIX has a
.BR prctl ()
get the maximum number of processors the calling process can use,
find out whether a specified process is currently blocked,
get or set the maximum stack size, and so on.
-.SH "SEE ALSO"
+.SH SEE ALSO
.BR signal (2),
.BR core (5)
+.SH COLOPHON
+This page is part of release 3.65 of the Linux
+.I man-pages
+project.
+A description of the project,
+and information about reporting bugs,
+can be found at
+\%http://www.kernel.org/doc/man\-pages/.
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