3 files changed, 132 insertions, 92 deletions
diff --git a/man/man2/prctl.2 b/man/man2/prctl.2
index f2e0b453ef..2c46923e40 100644
--- a/man/man2/prctl.2
+++ b/man/man2/prctl.2
@@ -25,7 +25,6 @@
 .\" 2012-10-25 Michael Kerrisk, Document PR_SET_TIMERSLACK and
 .\"                             PR_GET_TIMERSLACK
 .\" 2013-01-10 Kees Cook, document PR_SET_PTRACER
-.\" 2014-11-10 Dave Hansen, document PR_MPX_{EN,DIS}ABLE_MANAGEMENT
 .\"
 .\"
 .TH prctl 2 (date) "Linux man-pages (unreleased)"
@@ -102,91 +101,10 @@ The first argument can be:
 .B PR_SET_MM
 .TQ
 .B PR_SET_VMA
-.\" prctl PR_MPX_ENABLE_MANAGEMENT
-.TP
+.TQ
 .B PR_MPX_ENABLE_MANAGEMENT
 .TQ
-.BR PR_MPX_DISABLE_MANAGEMENT " (since Linux 3.19, removed in Linux 5.4; only on x86)"
-.\" commit fe3d197f84319d3bce379a9c0dc17b1f48ad358c
-.\" See also http://lwn.net/Articles/582712/
-.\" See also https://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler
-Enable or disable kernel management of Memory Protection eXtensions (MPX)
-bounds tables.
-The
-.IR arg2 ,
-.IR arg3 ,
-.IR arg4 ,
-and
-.I arg5
-.\" commit e9d1b4f3c60997fe197bf0243cb4a41a44387a88
-arguments must be zero.
-.IP
-MPX is a hardware-assisted mechanism for performing bounds checking on
-pointers.
-It consists of a set of registers storing bounds information
-and a set of special instruction prefixes that tell the CPU on which
-instructions it should do bounds enforcement.
-There is a limited number of these registers and
-when there are more pointers than registers,
-their contents must be "spilled" into a set of tables.
-These tables are called "bounds tables" and the MPX
-.BR prctl ()
-operations control
-whether the kernel manages their allocation and freeing.
-.IP
-When management is enabled, the kernel will take over allocation
-and freeing of the bounds tables.
-It does this by trapping the #BR exceptions that result
-at first use of missing bounds tables and
-instead of delivering the exception to user space,
-it allocates the table and populates the bounds directory
-with the location of the new table.
-For freeing, the kernel checks to see if bounds tables are
-present for memory which is not allocated, and frees them if so.
-.IP
-Before enabling MPX management using
-.BR PR_MPX_ENABLE_MANAGEMENT ,
-the application must first have allocated a user-space buffer for
-the bounds directory and placed the location of that directory in the
-.I bndcfgu
-register.
-.IP
-These calls fail if the CPU or kernel does not support MPX.
-Kernel support for MPX is enabled via the
-.B CONFIG_X86_INTEL_MPX
-configuration option.
-You can check whether the CPU supports MPX by looking for the
-.I mpx
-CPUID bit, like with the following command:
-.IP
-.in +4n
-.EX
-cat /proc/cpuinfo | grep \[aq] mpx \[aq]
-.EE
-.in
-.IP
-A thread may not switch in or out of long (64-bit) mode while MPX is
-enabled.
-.IP
-All threads in a process are affected by these calls.
-.IP
-The child of a
-.BR fork (2)
-inherits the state of MPX management.
-During
-.BR execve (2),
-MPX management is reset to a state as if
 .B PR_MPX_DISABLE_MANAGEMENT
-had been called.
-.IP
-For further information on Intel MPX, see the kernel source file
-.IR Documentation/x86/intel_mpx.txt .
-.IP
-.\" commit f240652b6032b48ad7fa35c5e701cc4c8d697c0b
-.\" See also https://lkml.kernel.org/r/20190705175321.DB42F0AD@viggo.jf.intel.com
-Due to a lack of toolchain support,
-.BR PR_MPX_ENABLE_MANAGEMENT " and " PR_MPX_DISABLE_MANAGEMENT
-are not supported in Linux 5.4 and later.
 .\" prctl PR_SET_NAME
 .TP
 .BR PR_SET_NAME " (since Linux 2.6.9)"
@@ -1572,15 +1490,6 @@ the kernel or CPU does not support the requested speculation misfeature.
 .B ENXIO
 .I op
 was
-.B PR_MPX_ENABLE_MANAGEMENT
-or
-.B PR_MPX_DISABLE_MANAGEMENT
-and the kernel or the CPU does not support MPX management.
-Check that the kernel and processor have MPX support.
-.TP
-.B ENXIO
-.I op
-was
 .B PR_SET_SPECULATION_CTRL
 implies that the control of the selected speculation misfeature is not possible.
 See
@@ -1666,4 +1575,6 @@ glibc 2.0.6
 .BR PR_MCE_KILL_GET (2const),
 .BR PR_SET_MM (2const),
 .BR PR_SET_VMA (2const),
+.BR PR_MPX_ENABLE_MANAGEMENT (2const),
+.BR PR_MPX_DISABLE_MANAGEMENT (2const),
 .BR core (5)
diff --git a/man/man2const/PR_MPX_DISABLE_MANAGEMENT.2const b/man/man2const/PR_MPX_DISABLE_MANAGEMENT.2const
new file mode 100644
index 0000000000..028bde11a5
--- /dev/null
+++ b/man/man2const/PR_MPX_DISABLE_MANAGEMENT.2const
@@ -0,0 +1 @@
+.so man2const/PR_MPX_ENABLE_MANAGEMENT.2const
diff --git a/man/man2const/PR_MPX_ENABLE_MANAGEMENT.2const b/man/man2const/PR_MPX_ENABLE_MANAGEMENT.2const
new file mode 100644
index 0000000000..5f18c2fe3f
--- /dev/null
+++ b/man/man2const/PR_MPX_ENABLE_MANAGEMENT.2const
@@ -0,0 +1,128 @@
+.\" Copyright 2014, Dave Hansen / Intel
+.\" Copyright 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2014-11-10 Dave Hansen, document PR_MPX_{EN,DIS}ABLE_MANAGEMENT
+.\"
+.TH PR_MPX_ENABLE_MANAGEMENT 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+PR_MPX_ENABLE_MANAGEMENT,
+PR_MPX_DISABLE_MANAGEMENT
+\-
+enable or disable kernel management of Memory Protection eXtensions (MPX)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/prctl.h>
+.P
+.BI "int prctl(int " op ", ...);"
+.fi
+.SH DESCRIPTION
+.TP
+.B PR_MPX_ENABLE_MANAGEMENT
+.TQ
+.BR PR_MPX_DISABLE_MANAGEMENT " (since Linux 3.19, removed in Linux 5.4; only on x86)"
+.\" commit fe3d197f84319d3bce379a9c0dc17b1f48ad358c
+.\" See also http://lwn.net/Articles/582712/
+.\" See also https://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler
+Enable or disable kernel management of Memory Protection eXtensions (MPX)
+bounds tables.
+The
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+.\" commit e9d1b4f3c60997fe197bf0243cb4a41a44387a88
+arguments must be zero.
+.IP
+MPX is a hardware-assisted mechanism for performing bounds checking on
+pointers.
+It consists of a set of registers storing bounds information
+and a set of special instruction prefixes that tell the CPU on which
+instructions it should do bounds enforcement.
+There is a limited number of these registers and
+when there are more pointers than registers,
+their contents must be "spilled" into a set of tables.
+These tables are called "bounds tables" and the MPX
+.BR prctl ()
+operations control
+whether the kernel manages their allocation and freeing.
+.IP
+When management is enabled, the kernel will take over allocation
+and freeing of the bounds tables.
+It does this by trapping the #BR exceptions that result
+at first use of missing bounds tables and
+instead of delivering the exception to user space,
+it allocates the table and populates the bounds directory
+with the location of the new table.
+For freeing, the kernel checks to see if bounds tables are
+present for memory which is not allocated, and frees them if so.
+.IP
+Before enabling MPX management using
+.BR PR_MPX_ENABLE_MANAGEMENT ,
+the application must first have allocated a user-space buffer for
+the bounds directory and placed the location of that directory in the
+.I bndcfgu
+register.
+.IP
+These calls fail if the CPU or kernel does not support MPX.
+Kernel support for MPX is enabled via the
+.B CONFIG_X86_INTEL_MPX
+configuration option.
+You can check whether the CPU supports MPX by looking for the
+.I mpx
+CPUID bit, like with the following command:
+.IP
+.in +4n
+.EX
+cat /proc/cpuinfo | grep \[aq] mpx \[aq]
+.EE
+.in
+.IP
+A thread may not switch in or out of long (64-bit) mode while MPX is
+enabled.
+.IP
+All threads in a process are affected by these calls.
+.IP
+The child of a
+.BR fork (2)
+inherits the state of MPX management.
+During
+.BR execve (2),
+MPX management is reset to a state as if
+.B PR_MPX_DISABLE_MANAGEMENT
+had been called.
+.IP
+For further information on Intel MPX, see the kernel source file
+.IR Documentation/x86/intel_mpx.txt .
+.IP
+.\" commit f240652b6032b48ad7fa35c5e701cc4c8d697c0b
+.\" See also https://lkml.kernel.org/r/20190705175321.DB42F0AD@viggo.jf.intel.com
+Due to a lack of toolchain support,
+.BR PR_MPX_ENABLE_MANAGEMENT " and " PR_MPX_DISABLE_MANAGEMENT
+are not supported in Linux 5.4 and later.
+.SH RETURN VALUE
+On success,
+0 is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B ENXIO
+.I op
+was
+.B PR_MPX_ENABLE_MANAGEMENT
+or
+.B PR_MPX_DISABLE_MANAGEMENT
+and the kernel or the CPU does not support MPX management.
+Check that the kernel and processor have MPX support.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.SH SEE ALSO
+.BR prctl (2)