personality.2: review, update for Linux 6.2

Settle on "no effect", concretify vaguely-described behaviours;
both [to be documented]s replaced with documentation
(these match my 6.2 checkout, if there were subtleties in the history
 they got lost).

Added the full system names to the PER_s that lacked them.

Didn't validate or chase down the versions except for PER_RISCOS.

Having these be sorted instead of in the original enumeration order is
really more trouble than it's worth.

Cf. the UAPI definition:
  /*
   * Personality types.
   *
   * These go in the low byte.  Avoid using the top bit, it will
   * conflict with error returns.
   */
  enum {
          PER_LINUX =             0x0000,
          PER_LINUX_32BIT =       0x0000 | ADDR_LIMIT_32BIT,
          PER_LINUX_FDPIC =       0x0000 | FDPIC_FUNCPTRS,
          PER_SVR4 =              0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
          PER_SVR3 =              0x0002 | STICKY_TIMEOUTS | SHORT_INODE,
          PER_SCOSVR3 =           0x0003 | STICKY_TIMEOUTS |
                                           WHOLE_SECONDS | SHORT_INODE,
          PER_OSR5 =              0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS,
          PER_WYSEV386 =          0x0004 | STICKY_TIMEOUTS | SHORT_INODE,
          PER_ISCR4 =             0x0005 | STICKY_TIMEOUTS,
          PER_BSD =               0x0006,
          PER_SUNOS =             0x0006 | STICKY_TIMEOUTS,
          PER_XENIX =             0x0007 | STICKY_TIMEOUTS | SHORT_INODE,
          PER_LINUX32 =           0x0008,
          PER_LINUX32_3GB =       0x0008 | ADDR_LIMIT_3GB,
          PER_IRIX32 =            0x0009 | STICKY_TIMEOUTS,/* IRIX5 32-bit */
          PER_IRIXN32 =           0x000a | STICKY_TIMEOUTS,/* IRIX6 new 32-bit */
          PER_IRIX64 =            0x000b | STICKY_TIMEOUTS,/* IRIX6 64-bit */
          PER_RISCOS =            0x000c,
          PER_SOLARIS =           0x000d | STICKY_TIMEOUTS,
          PER_UW7 =               0x000e | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
          PER_OSF4 =              0x000f,                  /* OSF/1 v4 */
          PER_HPUX =              0x0010,
          PER_MASK =              0x00ff,
  };

PER_LINUX is a base personality, PER_LINUX_{32BIT,FDPIC} are
PER_LINUX|ADDR_LIMIT_32BIT and PER_LINUX|FDPIC_FUNCPTRS, resp.

PER_BSD is a base personality, PER_SUNOS is PER_BSD|STICKY_TIMEOUTS.

PER_LINUX32 is a base personality, PER_LINUX32_3GB is
PER_LINUX32|ADDR_LIMIT_3GB.

I updated these all to be "Same as {base personality},
but implies {...}.". PER_SCOSVR3 has an "also", since it's the only one
where the base case PER_OSR5 has a list.

Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

1 files changed, 72 insertions, 31 deletions

diff --git a/man2/personality.2 b/man2/personality.2
index caca709b8..d9418b38e 100644
--- a/man2/personality.2
+++ b/man2/personality.2
@@ -67,10 +67,12 @@ With this flag set, use 0xc0000000 as the offset at which to search
 a virtual memory chunk on
 .BR mmap (2);
 otherwise use 0xffffe000.
+Applies to 32-bit x86 processes only.
 .TP
 .BR FDPIC_FUNCPTRS " (since Linux 2.6.11)"
 User-space function pointers to signal handlers point
-(on certain architectures) to descriptors.
+to descriptors.
+Applies only to ARM if BINFMT_ELF_FDPIC and SuperH.
 .TP
 .BR MMAP_PAGE_ZERO " (since Linux 2.4.0)"
 Map page 0 as read-only
@@ -85,7 +87,7 @@ for
 .BR mmap (2).
 .TP
 .BR SHORT_INODE " (since Linux 2.4.0)"
-No effects(?).
+No effect.
 .TP
 .BR STICKY_TIMEOUTS " (since Linux 1.2.0)"
 With this flag set,
@@ -99,7 +101,7 @@ interrupted by a signal handler.
 .BR UNAME26 " (since Linux 3.1)"
 Have
 .BR uname (2)
-report a 2.6.40+ version number rather than a 3.x version number.
+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.
@@ -127,111 +129,150 @@ Implies
 IRIX 6 64-bit.
 Implies
 .BR STICKY_TIMEOUTS ;
-otherwise no effects.
+otherwise no effect.
 .TP
 .BR PER_IRIXN32 " (since Linux 2.2)"
 IRIX 6 new 32-bit.
 Implies
 .BR STICKY_TIMEOUTS ;
-otherwise no effects.
+otherwise no effect.
 .TP
 .BR PER_ISCR4 " (since Linux 1.2.0)"
 Implies
 .BR STICKY_TIMEOUTS ;
-otherwise no effects.
+otherwise no effect.
 .TP
 .BR PER_LINUX " (since Linux 1.2.0)"
 Linux.
 .TP
 .BR PER_LINUX32 " (since Linux 2.2)"
-[To be documented.]
+.BR uname (2)
+returns the name of the 32-bit architecture in the
+.I machine
+field ("i686" instead of "x86_64", &c.).
+.IP
+Under ia64 (Itanium), processes with this personality don't have the
+O_LARGEFILE
+.BR open (2)
+flag forced.
+.IP
+Under 64-bit ARM, setting this personality is forbidden if
+.BR execve (2)ing
+a 32-bit process would also be forbidden
+(cf. the allow_mismatched_32bit_el0 kernel parameter and
+.IR Documentation/arm64/asymmetric-32bit.rst ).
 .TP
 .BR PER_LINUX32_3GB " (since Linux 2.4)"
-Implies
+Same as
+.BR PER_LINUX32 ,
+but implies
 .BR ADDR_LIMIT_3GB .
 .TP
 .BR PER_LINUX_32BIT " (since Linux 2.0)"
-Implies
+Same as
+.BR PER_LINUX ,
+but implies
 .BR ADDR_LIMIT_32BIT .
 .TP
 .BR PER_LINUX_FDPIC " (since Linux 2.6.11)"
-Implies
+Same as
+.BR PER_LINUX ,
+but implies
 .BR FDPIC_FUNCPTRS .
 .TP
 .BR PER_OSF4 " (since Linux 2.4)"
 OSF/1 v4.
-On alpha,
+.\" commit 987f20a9dcce3989e48d87cff3952c095c994445
+No effect since Linux 6.1, which removed a.out binary support.
+Before, on alpha,
 .\" Following is from a comment in arch/alpha/kernel/osf_sys.c
-clear top 32 bits of iov_len in the user's buffer for
+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.
 .IR int .
 .TP
 .BR PER_OSR5 " (since Linux 2.4)"
+SCO OpenServer 5.
 Implies
 .B STICKY_TIMEOUTS
 and
 .BR WHOLE_SECONDS ;
-otherwise no effects.
+otherwise no effect.
 .TP
-.BR PER_RISCOS " (since Linux 2.2)"
-[To be documented.]
+.BR PER_RISCOS " (since Linux 2.3.7; macro since Linux 2.3.13)"
+Acorn RISC OS/Arthur (MIPS).
+No effect.
+.\" commit 125ec7b4e90cbae4eed5a7ff1ee479cc331dcf3c
+Up to Linux v4.0, would set the emulation altroot to
+.I /usr/gnemul/riscos
+(cf.\&
+.BR PER_SUNOS,
+below).
+Before then, up to Linux 2.6.3, just Arthur emulation.
 .TP
 .BR PER_SCOSVR3 " (since Linux 1.2.0)"
-Implies
-.BR STICKY_TIMEOUTS ,
-.BR WHOLE_SECONDS ,
-and
-.BR SHORT_INODE ;
-otherwise no effects.
+SCO UNIX System V Release 3.
+Same as
+.BR PER_OSR5 ,
+but also implies
+.BR SHORT_INODE .
 .TP
 .BR PER_SOLARIS " (since Linux 2.4)"
+Solaris.
 Implies
 .BR STICKY_TIMEOUTS ;
-otherwise no effects.
+otherwise no effect.
 .TP
 .BR PER_SUNOS " (since Linux 2.4.0)"
-Implies
+Sun OS.
+Same as
+.BR PER_BSD ,
+but implies
 .BR STICKY_TIMEOUTS .
-Divert library and dynamic linker searches to
+Prior to Linux 2.6.26,
+diverted library and dynamic linker searches to
 .IR /usr/gnemul .
-Buggy, largely unmaintained, and almost entirely unused;
-support was removed in Linux 2.6.26.
+Buggy, largely unmaintained, and almost entirely unused.
 .TP
 .BR PER_SVR3 " (since Linux 1.2.0)"
+AT&T UNIX System V Release 3.
 Implies
 .B STICKY_TIMEOUTS
 and
 .BR SHORT_INODE ;
-otherwise no effects.
+otherwise no effect.
 .TP
 .BR PER_SVR4 " (since Linux 1.2.0)"
+AT&T UNIX System V Release 4.
 Implies
 .B STICKY_TIMEOUTS
 and
 .BR MMAP_PAGE_ZERO ;
-otherwise no effects.
+otherwise no effect.
 .TP
 .BR PER_UW7 " (since Linux 2.4)"
+UnixWare 7.
 Implies
 .B STICKY_TIMEOUTS
 and
 .BR MMAP_PAGE_ZERO ;
-otherwise no effects.
+otherwise no effect.
 .TP
 .BR PER_WYSEV386 " (since Linux 1.2.0)"
+WYSE UNIX System V/386.
 Implies
 .B STICKY_TIMEOUTS
 and
 .BR SHORT_INODE ;
-otherwise no effects.
+otherwise no effect.
 .TP
 .BR PER_XENIX " (since Linux 1.2.0)"
+XENIX.
 Implies
 .B STICKY_TIMEOUTS
 and
 .BR SHORT_INODE ;
-otherwise no effects.
+otherwise no effect.
 .SH RETURN VALUE
 On success, the previous
 .I persona