diff --git a/share/man/man9/p_candebug.9 b/share/man/man9/p_candebug.9
--- a/share/man/man9/p_candebug.9
+++ b/share/man/man9/p_candebug.9
@@ -1,5 +1,6 @@
 .\"
 .\" Copyright (c) 2003 Joseph Koshy <jkoshy@FreeBSD.org>
+.\" Copyright (c) 2023 Olivier Certner <olce.freebsd@certner.fr>
 .\"
 .\" All rights reserved.
 .\"
@@ -27,7 +28,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 19, 2006
+.Dd June 16, 2023
 .Dt P_CANDEBUG 9
 .Os
 .Sh NAME
@@ -41,22 +42,25 @@
 .Sh DESCRIPTION
 This function can be used to determine 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_visibility 9 .
 .Sh RETURN VALUES
 The
 .Fn p_candebug
@@ -70,36 +74,46 @@
 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
+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_visibility 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
+whole group set
+.Pq "including real, effective and saved group IDs" .
+.It Bq Er EPERM
+Thread
+.Fa td
+lacks superuser credentials and its (effective) user ID doesn't 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
-Thread
-.Fa td
-lacks super-user credentials and process
-.Fa p Ns 's
-group set is not a subset of
-.Fa td Ns 's
-effective group set.
-.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.
-.It Bq Er EPERM
 Process
 .Fa p
 denotes the initial process
@@ -109,30 +123,25 @@
 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_seeotheruids 9
-or
-.Xr cr_seeothergids 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_seeothergids 9 ,
-.Xr cr_seeotheruids 9 ,
+.Xr prison_check 9 ,
 .Xr mac 9 ,
-.Xr p_cansee 9 ,
-.Xr prison_check 9
+.Xr cr_bsd_visibility 9 ,
+.Xr procctl 2 ,
+.Xr p_cansee 9