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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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personality(2) System Calls Manual personality(2)
personality - set the process execution domain
Standard C library (libc, -lc)
#include <sys/personality.h>
int personality(unsigned long persona);
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 execution 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/personality.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 architectural 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. Applies to 32-bit x86 processes only.
FDPIC_FUNCPTRS (since Linux 2.6.11)
User-space function pointers to signal handlers point to
descriptors. Applies only to ARM if BINFMT_ELF_FDPIC and
SuperH.
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 effect.
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 signal handler.
UNAME26 (since Linux 3.1)
Have uname(2) report a 2.6.(40+x) version number rather
than a MAJOR.x version number. Added as a stopgap measure
to support broken applications that could not handle the
kernel version-numbering switch from Linux 2.6.x to Linux
3.x.
WHOLE_SECONDS (since Linux 1.2.0)
No effect.
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
effect.
PER_IRIXN32 (since Linux 2.2)
IRIX 6 new 32-bit. Implies STICKY_TIMEOUTS; otherwise no
effect.
PER_ISCR4 (since Linux 1.2.0)
Implies STICKY_TIMEOUTS; otherwise no effect.
PER_LINUX (since Linux 1.2.0)
Linux.
PER_LINUX32 (since Linux 2.2)
uname(2) returns the name of the 32-bit architecture in
the machine field ("i686" instead of "x86_64", &c.).
Under ia64 (Itanium), processes with this personality
don't have the O_LARGEFILE open(2) flag forced.
Under 64-bit ARM, setting this personality is forbidden if
execve(2)ing a 32-bit process would also be forbidden (cf.
the allow_mismatched_32bit_el0 kernel parameter and
Documentation/arm64/asymmetric-32bit.rst).
PER_LINUX32_3GB (since Linux 2.4)
Same as PER_LINUX32, but implies ADDR_LIMIT_3GB.
PER_LINUX_32BIT (since Linux 2.0)
Same as PER_LINUX, but implies ADDR_LIMIT_32BIT.
PER_LINUX_FDPIC (since Linux 2.6.11)
Same as PER_LINUX, but implies FDPIC_FUNCPTRS.
PER_OSF4 (since Linux 2.4)
OSF/1 v4. No effect since Linux 6.1, which removed a.out
binary support. Before, on alpha, would 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)
SCO OpenServer 5. Implies STICKY_TIMEOUTS and
WHOLE_SECONDS; otherwise no effect.
PER_RISCOS (since Linux 2.3.7; macro since Linux 2.3.13)
Acorn RISC OS/Arthur (MIPS). No effect. Up to Linux
v4.0, would set the emulation altroot to
/usr/gnemul/riscos (cf. PER_SUNOS, below). Before then,
up to Linux 2.6.3, just Arthur emulation.
PER_SCOSVR3 (since Linux 1.2.0)
SCO UNIX System V Release 3. Same as PER_OSR5, but also
implies SHORT_INODE.
PER_SOLARIS (since Linux 2.4)
Solaris. Implies STICKY_TIMEOUTS; otherwise no effect.
PER_SUNOS (since Linux 2.4.0)
Sun OS. Same as PER_BSD, but implies STICKY_TIMEOUTS.
Prior to Linux 2.6.26, diverted library and dynamic linker
searches to /usr/gnemul. Buggy, largely unmaintained, and
almost entirely unused.
PER_SVR3 (since Linux 1.2.0)
AT&T UNIX System V Release 3. Implies STICKY_TIMEOUTS and
SHORT_INODE; otherwise no effect.
PER_SVR4 (since Linux 1.2.0)
AT&T UNIX System V Release 4. Implies STICKY_TIMEOUTS and
MMAP_PAGE_ZERO; otherwise no effect.
PER_UW7 (since Linux 2.4)
UnixWare 7. Implies STICKY_TIMEOUTS and MMAP_PAGE_ZERO;
otherwise no effect.
PER_WYSEV386 (since Linux 1.2.0)
WYSE UNIX System V/386. Implies STICKY_TIMEOUTS and
SHORT_INODE; otherwise no effect.
PER_XENIX (since Linux 1.2.0)
XENIX. Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise
no effect.
On success, the previous persona is returned. On error, -1 is
returned, and errno is set to indicate the error.
EINVAL The kernel was unable to change the personality.
Linux.
Linux 1.1.20, glibc 2.3.
setarch(8)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.9.1 2024-05-02 personality(2)
Pages that refer to this page: mprotect(2), syscalls(2), proc_pid_personality(5), systemd.exec(5), systemd.unit(5), setarch(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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