PERSONALITY(2) Linux Programmer's Manual PERSONALITY(2)
NAME
personality - set the process execution domain
SYNOPSIS
#include <sys/personality.h>
int personality(unsigned long persona);
DESCRIPTION
Linux supports different execution domains, or personalities, for each
process. Among other things, execution domains tell Linux how to map
signal numbers into signal actions. The execution domain system allows
Linux to provide limited support for binaries compiled under other
UNIX-like operating systems.
If persona is not 0xffffffff, then personality() sets the caller's exe-
cution domain to the value specified by persona. Specifying persona as
0xffffffff provides a way of retrieving the current persona without
changing it.
A list of the available execution domains can be found in <sys/person-
ality.h>. The execution domain is a 32-bit value in which the top
three bytes are set aside for flags that cause the kernel to modify the
behavior of certain system calls so as to emulate historical or archi-
tectural quirks. The least significant byte is a value defining the
personality the kernel should assume. The flag values are as follows:
ADDR_COMPAT_LAYOUT (since Linux 2.6.9)
With this flag set, provide legacy virtual address space layout.
ADDR_NO_RANDOMIZE (since Linux 2.6.12)
With this flag set, disable address-space-layout randomization.
ADDR_LIMIT_32BIT (since Linux 2.2)
Limit the address space to 32 bits.
ADDR_LIMIT_3GB (since Linux 2.4.0)
With this flag set, use 0xc0000000 as the offset at which to
search a virtual memory chunk on mmap(2); otherwise use
0xffffe000.
FDPIC_FUNCPTRS (since Linux 2.6.11)
User-space function pointers to signal handlers point (on cer-
tain architectures) to descriptors.
MMAP_PAGE_ZERO (since Linux 2.4.0)
Map page 0 as read-only (to support binaries that depend on this
SVr4 behavior).
READ_IMPLIES_EXEC (since Linux 2.6.8)
With this flag set, PROT_READ implies PROT_EXEC for mmap(2).
SHORT_INODE (since Linux 2.4.0)
No effects(?).
STICKY_TIMEOUTS (since Linux 1.2.0)
With this flag set, select(2), pselect(2), and ppoll(2) do not
modify the returned timeout argument when interrupted by a sig-
nal handler.
UNAME26 (since Linux 3.1)
Have uname(2) report a 2.6.40+ version number rather than a 3.x
version number. Added as a stopgap measure to support broken
applications that could not handle the kernel version-numbering
switch from 2.6.x to 3.x.
WHOLE_SECONDS (since Linux 1.2.0)
No effects(?).
The available execution domains are:
PER_BSD (since Linux 1.2.0)
BSD. (No effects.)
PER_HPUX (since Linux 2.4)
Support for 32-bit HP/UX. This support was never complete, and
was dropped so that since Linux 4.0, this value has no effect.
PER_IRIX32 (since Linux 2.2)
IRIX 5 32-bit. Never fully functional; support dropped in Linux
2.6.27. Implies STICKY_TIMEOUTS.
PER_IRIX64 (since Linux 2.2)
IRIX 6 64-bit. Implies STICKY_TIMEOUTS; otherwise no effects.
PER_IRIXN32 (since Linux 2.2)
IRIX 6 new 32-bit. Implies STICKY_TIMEOUTS; otherwise no ef-
fects.
PER_ISCR4 (since Linux 1.2.0)
Implies STICKY_TIMEOUTS; otherwise no effects.
PER_LINUX (since Linux 1.2.0)
Linux.
PER_LINUX32 (since Linux 2.2)
[To be documented.]
PER_LINUX32_3GB (since Linux 2.4)
Implies ADDR_LIMIT_3GB.
PER_LINUX_32BIT (since Linux 2.0)
Implies ADDR_LIMIT_32BIT.
PER_LINUX_FDPIC (since Linux 2.6.11)
Implies FDPIC_FUNCPTRS.
PER_OSF4 (since Linux 2.4)
OSF/1 v4. On alpha, clear top 32 bits of iov_len in the user's
buffer for compatibility with old versions of OSF/1 where
iov_len was defined as. int.
PER_OSR5 (since Linux 2.4)
Implies STICKY_TIMEOUTS and WHOLE_SECONDS; otherwise no effects.
PER_RISCOS (since Linux 2.2)
[To be documented.]
PER_SCOSVR3 (since Linux 1.2.0)
Implies STICKY_TIMEOUTS, WHOLE_SECONDS, and SHORT_INODE; other-
wise no effects.
PER_SOLARIS (since Linux 2.4)
Implies STICKY_TIMEOUTS; otherwise no effects.
PER_SUNOS (since Linux 2.4.0)
Implies STICKY_TIMEOUTS. Divert library and dynamic linker
searches to /usr/gnemul. Buggy, largely unmaintained, and al-
most entirely unused; support was removed in Linux 2.6.26.
PER_SVR3 (since Linux 1.2.0)
Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.
PER_SVR4 (since Linux 1.2.0)
Implies STICKY_TIMEOUTS and MMAP_PAGE_ZERO; otherwise no ef-
fects.
PER_UW7 (since Linux 2.4)
Implies STICKY_TIMEOUTS and MMAP_PAGE_ZERO; otherwise no ef-
fects.
PER_WYSEV386 (since Linux 1.2.0)
Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.
PER_XENIX (since Linux 1.2.0)
Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.
RETURN VALUE
On success, the previous persona is returned. On error, -1 is re-
turned, and errno is set appropriately.
ERRORS
EINVAL The kernel was unable to change the personality.
VERSIONS
This system call first appeared in Linux 1.1.20 (and thus first in a
stable kernel release with Linux 1.2.0); library support was added in
glibc 2.3.
CONFORMING TO
personality() is Linux-specific and should not be used in programs in-
tended to be portable.
SEE ALSO
setarch(8)
COLOPHON
This page is part of release 5.07 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
https://www.kernel.org/doc/man-pages/.
Linux 2017-09-15 PERSONALITY(2)