diff --git a/share/man/man9/p_candebug.9 b/share/man/man9/p_candebug.9
index e80d313de55c..c824db974154 100644
--- a/share/man/man9/p_candebug.9
+++ b/share/man/man9/p_candebug.9
@@ -1,136 +1,145 @@
 .\"
 .\" Copyright (c) 2003 Joseph Koshy <jkoshy@FreeBSD.org>
+.\" Copyright (c) 2023 Olivier Certner <olce.freebsd@certner.fr>
 .\"
 .\" All rights reserved.
 .\"
 .\" This program is free software.
 .\"
 .\" Redistribution and use in source and binary forms, with or without
 .\" modification, are permitted provided that the following conditions
 .\" are met:
 .\" 1. Redistributions of source code must retain the above copyright
 .\"    notice, this list of conditions and the following disclaimer.
 .\" 2. Redistributions in binary form must reproduce the above copyright
 .\"    notice, this list of conditions and the following disclaimer in the
 .\"    documentation and/or other materials provided with the distribution.
 .\"
 .\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 .\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd November 19, 2006
+.Dd August 18, 2023
 .Dt P_CANDEBUG 9
 .Os
 .Sh NAME
 .Nm p_candebug
 .Nd determine debuggability of a process
 .Sh SYNOPSIS
 .In sys/param.h
 .In sys/proc.h
 .Ft int
 .Fn p_candebug "struct thread *td" "struct proc *p"
 .Sh DESCRIPTION
-This function can be used to determine if a given process
+This function determines if a given process
 .Fa p
-is debuggable by the thread
+is debuggable by some thread
 .Fa td .
-.Sh SYSCTL VARIABLES
+.Pp
 The following
 .Xr sysctl 8
 variables directly influence the behaviour of
 .Fn p_candebug :
 .Bl -tag -width indent
+.It Va security.bsd.unprivileged_proc_debug
+Must be set to a non-zero value to allow unprivileged processes
+access to the kernel's debug facilities.
 .It Va kern.securelevel
 Debugging of the init process is not allowed if this variable is
 .Li 1
 or greater.
-.It Va security.bsd.unprivileged_proc_debug
-Must be set to a non-zero value to allow unprivileged processes
-access to the kernel's debug facilities.
 .El
+.Pp
+Other such variables indirectly influence it; see
+.Xr cr_bsd_visible 9 .
 .Sh RETURN VALUES
 The
 .Fn p_candebug
 function
 returns
 .Li 0
 if the process denoted by
 .Fa p
 is debuggable by thread
 .Fa td ,
 or a non-zero error return value otherwise.
 .Sh ERRORS
 .Bl -tag -width Er
-.It Bq Er EACCESS
-The MAC subsystem denied debuggability.
-.It Bq Er EAGAIN
-Process
-.Fa p
-is in the process of being
-.Fn exec Ns 'ed.
 .It Bq Er EPERM
+An unprivileged process attempted to debug another process but the system is
+configured to deny it
+.Po
+see
+.Xr sysctl 8
+variable
+.Va security.bsd.unprivileged_proc_debug
+above
+.Pc .
+.It Bq Er ESRCH
 Thread
 .Fa td
-lacks super-user credentials and process
-.Fa p
-is executing a set-user-ID or set-group-ID executable.
+has been jailed and the process to debug does not belong to the same jail or one
+of its sub-jails, as determined by
+.Xr prison_check 9 .
+.It Bq Er ESRCH
+.Xr cr_bsd_visible 9
+denied visibility according to the BSD security policies in force.
 .It Bq Er EPERM
 Thread
 .Fa td
-lacks super-user credentials and process
+lacks superuser credentials and its (effective) group set is not a superset of
+process
 .Fa p Ns 's
-group set is not a subset of
-.Fa td Ns 's
-effective group set.
+whole group set
+.Pq "including real, effective and saved group IDs" .
 .It Bq Er EPERM
 Thread
 .Fa td
-lacks super-user credentials and process
-.Fa p Ns 's
-user IDs do not match thread
-.Fa td Ns 's
-effective user ID.
+lacks superuser credentials and its (effective) user ID does not match all user
+IDs of process
+.Fa p .
+.It Bq Er EPERM
+Thread
+.Fa td
+lacks superuser credentials and process
+.Fa p
+is executing a set-user-ID or set-group-ID executable.
 .It Bq Er EPERM
 Process
 .Fa p
 denotes the initial process
 .Fn initproc
 and the
 .Xr sysctl 8
 variable
 .Va kern.securelevel
 is greater than zero.
-.It Bq Er ESRCH
+.It Bq Er EBUSY
 Process
 .Fa p
-is not visible to thread
-.Fa td
-as determined by
-.Xr cr_canseeotheruids 9
-or
-.Xr cr_canseeothergids 9 .
-.It Bq Er ESRCH
-Thread
-.Fa td
-has been jailed and process
+is in the process of being
+.Fn exec Ns 'ed.
+.It Bq Er EPERM
+Process
 .Fa p
-does not belong to the same jail as
-.Fa td .
-.It Bq Er ESRCH
-The MAC subsystem denied debuggability.
+denied debuggability
+.Po
+see
+.Xr procctl 2 ,
+command
+.Dv PROC_TRACE_CTL
+.Pc .
 .El
 .Sh SEE ALSO
-.Xr jail 2 ,
-.Xr sysctl 8 ,
-.Xr cr_canseeothergids 9 ,
-.Xr cr_canseeotheruids 9 ,
+.Xr prison_check 9 ,
 .Xr mac 9 ,
-.Xr p_cansee 9 ,
-.Xr prison_check 9
+.Xr cr_bsd_visible 9 ,
+.Xr procctl 2 ,
+.Xr p_cansee 9