1PERSONALITY(2)             Linux Programmer's Manual            PERSONALITY(2)
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NAME

6       personality - set the process execution domain
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SYNOPSIS

9       #include <sys/personality.h>
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11       int personality(unsigned long persona);
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DESCRIPTION

14       Linux  supports different execution domains, or personalities, for each
15       process.  Among other things, execution domains tell Linux how  to  map
16       signal numbers into signal actions.  The execution domain system allows
17       Linux to provide limited support  for  binaries  compiled  under  other
18       UNIX-like operating systems.
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20       If persona is not 0xffffffff, then personality() sets the caller's exe‐
21       cution domain to the value specified by persona.  Specifying persona as
22       0xffffffff  provides  a  way  of retrieving the current persona without
23       changing it.
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25       A list of the available execution domains can be found in  <sys/person‐
26       ality.h>.   The  execution  domain  is  a 32-bit value in which the top
27       three bytes are set aside for flags that cause the kernel to modify the
28       behavior  of certain system calls so as to emulate historical or archi‐
29       tectural quirks.  The least significant byte is a  value  defining  the
30       personality the kernel should assume.  The flag values are as follows:
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32       ADDR_COMPAT_LAYOUT (since Linux 2.6.9)
33              With this flag set, provide legacy virtual address space layout.
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35       ADDR_NO_RANDOMIZE (since Linux 2.6.12)
36              With this flag set, disable address-space-layout randomization.
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38       ADDR_LIMIT_32BIT (since Linux 2.2)
39              Limit the address space to 32 bits.
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41       ADDR_LIMIT_3GB (since Linux 2.4.0)
42              With  this  flag  set,  use 0xc0000000 as the offset at which to
43              search  a  virtual  memory  chunk  on  mmap(2);  otherwise   use
44              0xffffe000.
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46       FDPIC_FUNCPTRS (since Linux 2.6.11)
47              User-space  function  pointers to signal handlers point (on cer‐
48              tain architectures) to descriptors.
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50       MMAP_PAGE_ZERO (since Linux 2.4.0)
51              Map page 0 as read-only (to support binaries that depend on this
52              SVr4 behavior).
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54       READ_IMPLIES_EXEC (since Linux 2.6.8)
55              With this flag set, PROT_READ implies PROT_EXEC for mmap(2).
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57       SHORT_INODE (since Linux 2.4.0)
58              No effects(?).
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60       STICKY_TIMEOUTS (since Linux 1.2.0)
61              With  this  flag set, select(2), pselect(2), and ppoll(2) do not
62              modify the returned timeout argument when interrupted by a  sig‐
63              nal handler.
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65       UNAME26 (since Linux 3.1)
66              Have  uname(2) report a 2.6.40+ version number rather than a 3.x
67              version number.  Added as a stopgap measure  to  support  broken
68              applications  that could not handle the kernel version-numbering
69              switch from 2.6.x to 3.x.
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71       WHOLE_SECONDS (since Linux 1.2.0)
72              No effects(?).
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74       The available execution domains are:
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76       PER_BSD (since Linux 1.2.0)
77              BSD. (No effects.)
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79       PER_HPUX (since Linux 2.4)
80              Support for 32-bit HP/UX.  This support was never complete,  and
81              was dropped so that since Linux 4.0, this value has no effect.
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83       PER_IRIX32 (since Linux 2.2)
84              IRIX 5 32-bit.  Never fully functional; support dropped in Linux
85              2.6.27.  Implies STICKY_TIMEOUTS.
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87       PER_IRIX64 (since Linux 2.2)
88              IRIX 6 64-bit.  Implies STICKY_TIMEOUTS; otherwise no effects.
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90       PER_IRIXN32 (since Linux 2.2)
91              IRIX 6 new 32-bit.  Implies STICKY_TIMEOUTS;  otherwise  no  ef‐
92              fects.
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94       PER_ISCR4 (since Linux 1.2.0)
95              Implies STICKY_TIMEOUTS; otherwise no effects.
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97       PER_LINUX (since Linux 1.2.0)
98              Linux.
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100       PER_LINUX32 (since Linux 2.2)
101              [To be documented.]
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103       PER_LINUX32_3GB (since Linux 2.4)
104              Implies ADDR_LIMIT_3GB.
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106       PER_LINUX_32BIT (since Linux 2.0)
107              Implies ADDR_LIMIT_32BIT.
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109       PER_LINUX_FDPIC (since Linux 2.6.11)
110              Implies FDPIC_FUNCPTRS.
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112       PER_OSF4 (since Linux 2.4)
113              OSF/1  v4.  On alpha, clear top 32 bits of iov_len in the user's
114              buffer for  compatibility  with  old  versions  of  OSF/1  where
115              iov_len was defined as.  int.
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117       PER_OSR5 (since Linux 2.4)
118              Implies STICKY_TIMEOUTS and WHOLE_SECONDS; otherwise no effects.
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120       PER_RISCOS (since Linux 2.2)
121              [To be documented.]
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123       PER_SCOSVR3 (since Linux 1.2.0)
124              Implies  STICKY_TIMEOUTS, WHOLE_SECONDS, and SHORT_INODE; other‐
125              wise no effects.
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127       PER_SOLARIS (since Linux 2.4)
128              Implies STICKY_TIMEOUTS; otherwise no effects.
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130       PER_SUNOS (since Linux 2.4.0)
131              Implies STICKY_TIMEOUTS.   Divert  library  and  dynamic  linker
132              searches  to  /usr/gnemul.  Buggy, largely unmaintained, and al‐
133              most entirely unused; support was removed in Linux 2.6.26.
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135       PER_SVR3 (since Linux 1.2.0)
136              Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.
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138       PER_SVR4 (since Linux 1.2.0)
139              Implies STICKY_TIMEOUTS and  MMAP_PAGE_ZERO;  otherwise  no  ef‐
140              fects.
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142       PER_UW7 (since Linux 2.4)
143              Implies  STICKY_TIMEOUTS  and  MMAP_PAGE_ZERO;  otherwise no ef‐
144              fects.
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146       PER_WYSEV386 (since Linux 1.2.0)
147              Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.
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149       PER_XENIX (since Linux 1.2.0)
150              Implies STICKY_TIMEOUTS and SHORT_INODE; otherwise no effects.
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RETURN VALUE

153       On success, the previous persona is returned.   On  error,  -1  is  re‐
154       turned, and errno is set to indicate the error.
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ERRORS

157       EINVAL The kernel was unable to change the personality.
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VERSIONS

160       This  system  call  first appeared in Linux 1.1.20 (and thus first in a
161       stable kernel release with Linux 1.2.0); library support was  added  in
162       glibc 2.3.
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CONFORMING TO

165       personality()  is Linux-specific and should not be used in programs in‐
166       tended to be portable.
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SEE ALSO

169       setarch(8)
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COLOPHON

172       This page is part of release 5.13 of the Linux  man-pages  project.   A
173       description  of  the project, information about reporting bugs, and the
174       latest    version    of    this    page,    can     be     found     at
175       https://www.kernel.org/doc/man-pages/.
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179Linux                             2021-03-22                    PERSONALITY(2)
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