port-alpha/57701: alpha kernel is built with RWX segment

[campbell+netbsd%mumble.net@localhost]

>Number:         57701
>Category:       port-alpha
>Synopsis:       alpha kernel is built with RWX segment
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-alpha-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Nov 18 03:50:00 +0000 2023
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The NetBSD LDation
>Environment:
>Description:
/space/tools/bin/../lib/gcc/alpha--netbsd/10.5.0/../../../../alpha--netbsd/bin/ld: warning: cc1 has a LOAD segment with RWX permissions

The kernel image should have finer-grained permissions so the CPU doesn't allow, e.g., writing to the text segment.
>How-To-Repeat:
link an alpha kernel
>Fix:
Teach sys/arch/alpha/conf/kern.ldscript to use separate program segments for read/execute, read/write, and read-only parts of the kernel.