NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | SEE ALSO | COLOPHON

PRCTL(2)                  Linux Programmer's Manual                 PRCTL(2)

NAME         top

       prctl - operations on a process

SYNOPSIS         top

       #include <sys/prctl.h>

       int prctl(int option, unsigned long arg2, unsigned long arg3,
                 unsigned long arg4, unsigned long arg5);

DESCRIPTION         top

       prctl() is called with a first argument describing what to do (with
       values defined in <linux/prctl.h>), and further arguments with a
       significance depending on the first one.  The first argument can be:

       PR_CAPBSET_READ (since Linux 2.6.25)
              Return (as the function result) 1 if the capability specified
              in arg2 is in the calling thread's capability bounding set, or
              0 if it is not.  (The capability constants are defined in
              <linux/capability.h>.)  The capability bounding set dictates
              whether the process can receive the capability through a
              file's permitted capability set on a subsequent call to
              execve(2).

              If the capability specified in arg2 is not valid, then the
              call fails with the error EINVAL.

       PR_CAPBSET_DROP (since Linux 2.6.25)
              If the calling thread has the CAP_SETPCAP capability, then
              drop the capability specified by arg2 from the calling
              thread's capability bounding set.  Any children of the calling
              thread will inherit the newly reduced bounding set.

              The call fails with the error: EPERM if the calling thread
              does not have the CAP_SETPCAP; EINVAL if arg2 does not
              represent a valid capability; or EINVAL if file capabilities
              are not enabled in the kernel, in which case bounding sets are
              not supported.

       PR_SET_CHILD_SUBREAPER (since Linux 3.4)
              If arg2 is nonzero, set the "child subreaper" attribute of the
              calling process; if 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 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 SIGCHLD
              signal and be able to wait(2) on the process to discover its
              termination status.

       PR_GET_CHILD_SUBREAPER (since Linux 3.4)
              Return the "child subreaper" setting of the caller, in the
              location pointed to by (int *) arg2.

       PR_SET_DUMPABLE (since Linux 2.3.20)
              Set the state of the flag determining whether core dumps are
              produced 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
              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, arg2 must be
              either 0 (process is not dumpable) or 1 (process is dumpable).
              Between kernels 2.6.13 and 2.6.17, the value 2 was also
              permitted, which caused any binary which normally would not be
              dumped to be dumped readable by root only; for security
              reasons, this feature has been removed.  (See also the
              description of /proc/sys/fs/suid_dumpable in proc(5).)
              Processes that are not dumpable can not be attached via
              ptrace(2) PTRACE_ATTACH.

       PR_GET_DUMPABLE (since Linux 2.3.20)
              Return (as the function result) the current state of the
              calling process's dumpable flag.

       PR_SET_ENDIAN (since Linux 2.6.18, PowerPC only)
              Set the endian-ness of the calling process to the value given
              in arg2, which should be one of the following: PR_ENDIAN_BIG,
              PR_ENDIAN_LITTLE, or PR_ENDIAN_PPC_LITTLE (PowerPC pseudo
              little endian).

       PR_GET_ENDIAN (since Linux 2.6.18, PowerPC only)
              Return the endian-ness of the calling process, in the location
              pointed to by (int *) arg2.

       PR_SET_FPEMU (since Linux 2.4.18, 2.5.9, only on ia64)
              Set floating-point emulation control bits to arg2.  Pass
              PR_FPEMU_NOPRINT to silently emulate fp operations accesses,
              or PR_FPEMU_SIGFPE to not emulate fp operations and send
              SIGFPE instead.

       PR_GET_FPEMU (since Linux 2.4.18, 2.5.9, only on ia64)
              Return floating-point emulation control bits, in the location
              pointed to by (int *) arg2.

       PR_SET_FPEXC (since Linux 2.4.21, 2.5.32, only on PowerPC)
              Set floating-point exception mode to arg2.  Pass
              PR_FP_EXC_SW_ENABLE to use FPEXC for FP exception enables,
              PR_FP_EXC_DIV for floating-point divide by zero, PR_FP_EXC_OVF
              for floating-point overflow, PR_FP_EXC_UND for floating-point
              underflow, PR_FP_EXC_RES for floating-point inexact result,
              PR_FP_EXC_INV for floating-point invalid operation,
              PR_FP_EXC_DISABLED for FP exceptions disabled,
              PR_FP_EXC_NONRECOV for async nonrecoverable exception mode,
              PR_FP_EXC_ASYNC for async recoverable exception mode,
              PR_FP_EXC_PRECISE for precise exception mode.

       PR_GET_FPEXC (since Linux 2.4.21, 2.5.32, only on PowerPC)
              Return floating-point exception mode, in the location pointed
              to by (int *) arg2.

       PR_SET_KEEPCAPS (since Linux 2.2.18)
              Set the state of the thread's "keep capabilities" flag, which
              determines whether the threads's permitted capability set is
              cleared when a change is made to the threads's user IDs such
              that the threads's real UID, effective UID, and saved set-
              user-ID all become nonzero when at least one of them
              previously had the value 0.  By default, the permitted
              capability set is cleared when such a change is made; setting
              the "keep capabilities" flag prevents it from being cleared.
              arg2 must be either 0 (permitted capabilities are cleared) or
              1 (permitted capabilities are kept).  (A thread's effective
              capability set is always cleared when such a credential change
              is made, regardless of the setting of the "keep capabilities"
              flag.)  The "keep capabilities" value will be reset to 0 on
              subsequent calls to execve(2).

       PR_GET_KEEPCAPS (since Linux 2.2.18)
              Return (as the function result) the current state of the
              calling threads's "keep capabilities" flag.

       PR_SET_NAME (since Linux 2.6.9)
              Set the name of the calling thread, using the value in the
              location pointed to by (char *) arg2.  The name can be up to
              16 bytes long, and should be null-terminated if it contains
              fewer bytes.  This is the same attribute that can be set via
              pthread_setname_np(3) and retrieved using
              pthread_getname_np(3).  The attribute is likewise accessible
              via /proc/self/task/[tid]/comm, where tid is the name of the
              calling thread.

       PR_GET_NAME (since Linux 2.6.11)
              Return the name of the calling thread, in the buffer pointed
              to by (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.

       PR_SET_NO_NEW_PRIVS (since Linux 3.5)
              Set the calling process's no_new_privs bit to the value in
              arg2.  With no_new_privs set to 1, execve(2) promises not to
              grant privileges to do anything that could not have been done
              without the 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 fork(2) and clone(2), and preserved across
              execve(2).

              For more information, see the kernel source file
              Documentation/prctl/no_new_privs.txt.

       PR_GET_NO_NEW_PRIVS (since Linux 3.5)
              Return (as the function result) the value of the no_new_privs
              bit for the current process.  A value of 0 indicates the
              regular execve(2) behavior.  A value of 1 indicates execve(2)
              will operate in the privilege-restricting mode described
              above.

       PR_SET_PDEATHSIG (since Linux 2.1.57)
              Set the parent process death signal of the calling process to
              arg2 (either a signal value in the range 1..maxsig, or 0 to
              clear).  This is the signal that the calling process will get
              when its parent dies.  This value is cleared for the child of
              a fork(2) 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 execve(2).

       PR_GET_PDEATHSIG (since Linux 2.3.15)
              Return the current value of the parent process death signal,
              in the location pointed to by (int *) arg2.

       PR_SET_PTRACER (since Linux 3.4)
              This is meaningful only when the Yama LSM is enabled and in
              mode 1 ("restricted ptrace", visible via
              /proc/sys/kernel/yama/ptrace_scope).  When a "ptracer process
              ID" is passed in arg2, the caller is declaring that the
              ptracer process can ptrace(2) the calling process as if it
              were a direct process ancestor.  Each PR_SET_PTRACER operation
              replaces the previous "ptracer process ID".  Employing
              PR_SET_PTRACER with arg2 set to 0 clears the caller's "ptracer
              process ID".  If arg2 is 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
              Documentation/security/Yama.txt.

       PR_SET_SECCOMP (since Linux 2.6.23)
              Set the secure computing (seccomp) mode for the calling
              thread, to limit the available system calls.  The seccomp mode
              is selected via arg2.  (The seccomp constants are defined in
              <linux/seccomp.h>.)

              With arg2 set to SECCOMP_MODE_STRICT the only system calls
              that the thread is permitted to make are read(2), write(2),
              _exit(2), and sigreturn(2).  Other system calls result in the
              delivery of a SIGKILL signal.  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 available only if the
              kernel is configured with CONFIG_SECCOMP enabled.

              With arg2 set to SECCOMP_MODE_FILTER (since Linux 3.5) the
              system calls allowed are defined by a pointer to a Berkeley
              Packet Filter passed in arg3.  This argument is a pointer to
              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
              CONFIG_SECCOMP_FILTER enabled.

              If SECCOMP_MODE_FILTER filters permit fork(2), then the
              seccomp mode is inherited by children created by fork(2); if
              execve(2) is permitted, then the seccomp mode is preserved
              across execve(2).  If the filters permit 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
              Documentation/prctl/seccomp_filter.txt.

       PR_GET_SECCOMP (since Linux 2.6.23)
              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 prctl() call will cause a
              SIGKILL signal to be sent to the process.  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 CONFIG_SECCOMP enabled.

       PR_SET_SECUREBITS (since Linux 2.6.26)
              Set the "securebits" flags of the calling thread to the value
              supplied in arg2.  See capabilities(7).

       PR_GET_SECUREBITS (since Linux 2.6.26)
              Return (as the function result) the "securebits" flags of the
              calling thread.  See capabilities(7).

       PR_SET_THP_DISABLE (since Linux 3.15)
              Set the state of the "THP disable" flag for the calling
              thread.  If 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 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
              fork(2) and is preserved across execve(2).

       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.

       PR_GET_TID_ADDRESS (since Linux 3.5)
              Retrieve the clear_child_tid address set by set_tid_address(2)
              and the clone(2) CLONE_CHILD_CLEARTID flag, in the location
              pointed to by (int **) arg2.  This feature is available only
              if the kernel is built with the CONFIG_CHECKPOINT_RESTORE
              option enabled.

       PR_SET_TIMERSLACK (since Linux 2.6.28)
              Set the current timer slack for the calling thread to the
              nanosecond value supplied in arg2.  If arg2 is less than or
              equal to zero, 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
              select(2), pselect(2), poll(2), ppoll(2), epoll_wait(2),
              epoll_pwait(2), clock_nanosleep(2), nanosleep(2), and futex(2)
              (and thus the library functions implemented via futexes,
              including pthread_cond_timedwait(3),
              pthread_mutex_timedlock(3), pthread_rwlock_timedrdlock(3),
              pthread_rwlock_timedwrlock(3), and sem_timedwait(3)).

              Timer slack is not applied to threads that are scheduled under
              a real-time scheduling policy (see 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
              PR_SET_TIMERSLACK (the default value can't be changed).  The
              timer slack values of init (PID 1), the ancestor of all
              processes, are 50,000 nanoseconds (50 microseconds).  The
              timer slack values are preserved across execve(2).

       PR_GET_TIMERSLACK (since Linux 2.6.28)
              Return (as the function result) the current timer slack value
              of the calling thread.

       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
              PR_TIMING_STATISTICAL or PR_TIMING_TIMESTAMP to arg2.
              PR_TIMING_TIMESTAMP is not currently implemented (attempting
              to set this mode will yield the error EINVAL).

       PR_GET_TIMING (since Linux 2.6.0-test4)
              Return (as the function result) which process timing method is
              currently in use.

       PR_TASK_PERF_EVENTS_DISABLE (since Linux 2.6.31)
              Disable all performance counters attached to the calling
              process, regardless of whether the counters were created by
              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 Linux
              kernel source file tools/perf/design.txt.

              Originally called PR_TASK_PERF_COUNTERS_DISABLE; renamed (with
              same numerical value) in Linux 2.6.32.

       PR_TASK_PERF_EVENTS_ENABLE (since Linux 2.6.31)
              The converse of PR_TASK_PERF_EVENTS_DISABLE; enable
              performance counters attached to the calling process.

              Originally called PR_TASK_PERF_COUNTERS_ENABLE; renamed in
              Linux 2.6.32.

       PR_SET_TSC (since Linux 2.6.26, x86 only)
              Set the state of the flag determining whether the timestamp
              counter can be read by the process.  Pass PR_TSC_ENABLE to
              arg2 to allow it to be read, or PR_TSC_SIGSEGV to generate a
              SIGSEGV when the process tries to read the timestamp counter.

       PR_GET_TSC (since Linux 2.6.26, x86 only)
              Return the state of the flag determining whether the timestamp
              counter can be read, in the location pointed to by (int *)
              arg2.

       PR_SET_UNALIGN
              (Only on: ia64, since Linux 2.3.48; parisc, since Linux
              2.6.15; PowerPC, since Linux 2.6.18; Alpha, since Linux
              2.6.22) Set unaligned access control bits to arg2.  Pass
              PR_UNALIGN_NOPRINT to silently fix up unaligned user accesses,
              or PR_UNALIGN_SIGBUS to generate SIGBUS on unaligned user
              access.

       PR_GET_UNALIGN
              (see PR_SET_UNALIGN for information on versions and
              architectures) Return unaligned access control bits, in the
              location pointed to by (int *) arg2.

       PR_MCE_KILL (since Linux 2.6.32)
              Set the machine check memory corruption kill policy for the
              current thread.  If arg2 is PR_MCE_KILL_CLEAR, clear the
              thread memory corruption kill policy and use the system-wide
              default.  (The system-wide default is defined by
              /proc/sys/vm/memory_failure_early_kill; see proc(5).)  If arg2
              is PR_MCE_KILL_SET, use a thread-specific memory corruption
              kill policy.  In this case, arg3 defines whether the policy is
              early kill (PR_MCE_KILL_EARLY), late kill (PR_MCE_KILL_LATE),
              or the system-wide default (PR_MCE_KILL_DEFAULT).  Early kill
              means that the thread receives a SIGBUS signal as soon as
              hardware memory corruption is detected inside its address
              space.  In late kill mode, the process is killed only when it
              accesses a corrupted page.  See sigaction(2) for more
              information on the SIGBUS signal.  The policy is inherited by
              children.  The remaining unused prctl() arguments must be zero
              for future compatibility.

       PR_MCE_KILL_GET (since Linux 2.6.32)
              Return the current per-process machine check kill policy.  All
              unused prctl() arguments must be zero.

       PR_SET_MM (since Linux 3.3)
              Modify certain kernel memory map descriptor fields of the
              calling process.  Usually these fields are set by the kernel
              and dynamic loader (see ld.so(8) for more information) and a
              regular application should not use this feature.  However,
              there are cases, such as self-modifying programs, where a
              program might find it useful to change its own memory map.
              This feature is available only if the kernel is built with the
              CONFIG_CHECKPOINT_RESTORE option enabled.  The calling process
              must have the CAP_SYS_RESOURCE capability.  The value in arg2
              is one of the options below, while arg3 provides a new value
              for the option.

              PR_SET_MM_START_CODE
                     Set the address above which the program text can run.
                     The corresponding memory area must be readable and
                     executable, but not writable or sharable (see
                     mprotect(2) and mmap(2) for more information).

              PR_SET_MM_END_CODE
                     Set the address below which the program text can run.
                     The corresponding memory area must be readable and
                     executable, but not writable or sharable.

              PR_SET_MM_START_DATA
                     Set the address above which initialized and
                     uninitialized (bss) data are placed.  The corresponding
                     memory area must be readable and writable, but not
                     executable or sharable.

              PR_SET_MM_END_DATA
                     Set the address below which initialized and
                     uninitialized (bss) data are placed.  The corresponding
                     memory area must be readable and writable, but not
                     executable or sharable.

              PR_SET_MM_START_STACK
                     Set the start address of the stack.  The corresponding
                     memory area must be readable and writable.

              PR_SET_MM_START_BRK
                     Set the address above which the program heap can be
                     expanded with brk(2) call.  The address must be greater
                     than the ending address of the current program data
                     segment.  In addition, the combined size of the
                     resulting heap and the size of the data segment can't
                     exceed the RLIMIT_DATA resource limit (see
                     setrlimit(2)).

              PR_SET_MM_BRK
                     Set the current brk(2) value.  The requirements for the
                     address are the same as for the PR_SET_MM_START_BRK
                     option.

              The following options are available since Linux 3.5.

              PR_SET_MM_ARG_START
                     Set the address above which the program command line is
                     placed.

              PR_SET_MM_ARG_END
                     Set the address below which the program command line is
                     placed.

              PR_SET_MM_ENV_START
                     Set the address above which the program environment is
                     placed.

              PR_SET_MM_ENV_END
                     Set the address below which the program environment is
                     placed.

                     The address passed with PR_SET_MM_ARG_START,
                     PR_SET_MM_ARG_END, PR_SET_MM_ENV_START, and
                     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 MAP_GROWSDOWN attribute set
                     (see mmap(2)).

              PR_SET_MM_AUXV
                     Set a new auxiliary vector.  The arg3 argument should
                     provide the address of the vector.  The arg4 is the
                     size of the vector.

              PR_SET_MM_EXE_FILE
                     Supersede the /proc/pid/exe symbolic link with a new
                     one pointing to a new executable file identified by the
                     file descriptor provided in arg3 argument.  The file
                     descriptor should be obtained with a regular open(2)
                     call.

                     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 .text section).

                     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.

RETURN VALUE         top

       On success, PR_GET_DUMPABLE, PR_GET_KEEPCAPS, PR_GET_NO_NEW_PRIVS,
       PR_GET_THP_DISABLE, PR_CAPBSET_READ, PR_GET_TIMING,
       PR_GET_TIMERSLACK, PR_GET_SECUREBITS, PR_MCE_KILL_GET, and (if it
       returns) PR_GET_SECCOMP return the nonnegative values described
       above.  All other option values return 0 on success.  On error, -1 is
       returned, and errno is set appropriately.

ERRORS         top

       EFAULT arg2 is an invalid address.

       EINVAL The value of option is not recognized.

       EINVAL option is PR_MCE_KILL or PR_MCE_KILL_GET or PR_SET_MM, and
              unused prctl() arguments were not specified as zero.

       EINVAL arg2 is not valid value for this option.

       EINVAL option is PR_SET_SECCOMP or PR_GET_SECCOMP, and the kernel was
              not configured with CONFIG_SECCOMP.

       EINVAL option is PR_SET_MM, and one of the following is true

              *  arg4 or arg5 is nonzero;

              *  arg3 is greater than TASK_SIZE (the limit on the size of
                 the user address space for this architecture);

              *  arg2 is PR_SET_MM_START_CODE, PR_SET_MM_END_CODE,
                 PR_SET_MM_START_DATA, PR_SET_MM_END_DATA, or
                 PR_SET_MM_START_STACK, and the permissions of the
                 corresponding memory area are not as required;

              *  arg2 is PR_SET_MM_START_BRK or PR_SET_MM_BRK, and arg3 is
                 less than or equal to the end of the data segment or
                 specifies a value that would cause the RLIMIT_DATA resource
                 limit to be exceeded.

       EINVAL option is PR_SET_PTRACER and arg2 is not 0,
              PR_SET_PTRACER_ANY, or the PID of an existing process.

       EINVAL option is PR_SET_PDEATHSIG and arg2 is not a valid signal
              number.

       EINVAL option is PR_SET_DUMPABLE and arg2 is neither
              SUID_DUMP_DISABLE nor SUID_DUMP_USER.

       EINVAL option is PR_SET_TIMING and arg2 is not PR_TIMING_STATISTICAL.

       EINVAL option is PR_SET_NO_NEW_PRIVS and arg2 is not equal to 1 or
              arg3, arg4, or arg5 is nonzero.

       EINVAL option is PR_GET_NO_NEW_PRIVS and arg2, arg3, arg4, or arg5 is
              nonzero.

       EINVAL option is PR_SET_THP_DISABLE and arg3, arg4, or arg5 is
              nonzero.

       EINVAL option is PR_GET_THP_DISABLE and arg2, arg3, arg4, or arg5 is
              nonzero.

       EPERM  option is PR_SET_SECUREBITS, and the caller does not have the
              CAP_SETPCAP capability, or tried to unset a "locked" flag, or
              tried to set a flag whose corresponding locked flag was set
              (see capabilities(7)).

       EPERM  option is PR_SET_KEEPCAPS, and the callers's
              SECURE_KEEP_CAPS_LOCKED flag is set (see capabilities(7)).

       EPERM  option is PR_CAPBSET_DROP, and the caller does not have the
              CAP_SETPCAP capability.

       EPERM  option is PR_SET_MM, and the caller does not have the
              CAP_SYS_RESOURCE capability.

       EACCES option is PR_SET_MM, and arg3 is PR_SET_MM_EXE_FILE, the file
              is not executable.

       EBUSY  option is PR_SET_MM, arg3 is PR_SET_MM_EXE_FILE, and this the
              second attempt to change the /proc/pid/exe symbolic link,
              which is prohibited.

       EBADF  option is PR_SET_MM, arg3 is PR_SET_MM_EXE_FILE, and the file
              descriptor passed in arg4 is not valid.

VERSIONS         top

       The prctl() system call was introduced in Linux 2.1.57.

CONFORMING TO         top

       This call is Linux-specific.  IRIX has a prctl() system call (also
       introduced in Linux 2.1.44 as irix_prctl on the MIPS architecture),
       with prototype

       ptrdiff_t prctl(int option, int arg2, int arg3);

       and options to get the maximum number of processes per user, 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.

SEE ALSO         top

       signal(2), core(5)

COLOPHON         top

       This page is part of release 3.70 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       http://www.kernel.org/doc/man-pages/.

Linux                            2014-04-14                         PRCTL(2)