port-evbarm/60780: UBSan complains about left-shifting outside of int type range

["als%thangorodrim.ch@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60780
>Category:       port-evbarm
>Synopsis:       UBSan complains about left-shifting outside of int type range
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-evbarm-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Sep 23 20:55:00 +0000 2026
>Originator:     Alexander Schreiber
>Release:        HEAD/20260919024529Z
>Organization:
Not Much
>Environment:
Currently not available, but uname reports as evbmips 11.99.8
>Description:
HEAD/20260919024529Z configured with all available debug/diag options starts
spitting out complains from UBSan:

[   1.0000000] UBSan: Undefined Behavior in /usr/build/HEAD_20260919024529Z/usr/src/sys/arch/mips/mips/mips_machdep.c:1117:20, left shift of 55 by 26 places cannot be represented in type 'int'
[   1.0000000] UBSan: Undefined Behavior in /usr/build/HEAD_20260919024529Z/usr/src/sys/arch/mips/mips/mips_fixup.c:481:2, left shift of negative value -8
[   1.0000000] UBSan: Undefined Behavior in /usr/build/HEAD_20260919024529Z/usr/src/sys/arch/mips/mips/mips_fixup.c:491:46, left shift of negative value -8




>How-To-Repeat:
HEAD/20260919024529Z configured with all available debug/diag options:
----------------------- cut here -----------------------
--- OCTEON      2026-07-07 08:14:15.000000000 +0000
+++ ERLITE3     2026-09-21 20:42:03.269928587 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: OCTEON,v 1.19 2026/07/07 08:14:15 kbowling Exp $
+#      $NetBSD: OCTEON,v 1.14 2024/01/29 18:27:11 christos Exp $
 
 include        "arch/mips/conf/std.octeon"
 include        "arch/evbmips/conf/files.octeon"
@@ -12,6 +12,31 @@
 options        FDT
 options        FDT_DEFAULT_STDOUT_PATH="\"uart0:115200n8\""
 
+
+
+# MP
+options        MULTIPROCESSOR
+
+# Kernel Undefined Behavior Sanitizer (kUBSan).
+options        KUBSAN                  # mandatory
+#options        UBSAN_ALWAYS_FATAL      # optional: panic on all kUBSan reports
+
+# Kernel Code Coverage Driver.
+makeoptions    KCOV=1
+options        KCOV
+
+# Heartbeat checks
+options         HEARTBEAT
+options         HEARTBEAT_MAX_PERIOD_DEFAULT=15
+
+
+
+
+
+
+# config
+options                INCLUDE_CONFIG_FILE
+
 # Options for necessary to use MD
 #options       MEMORY_DISK_HOOKS
 #options       MEMORY_DISK_IS_ROOT     # force root on memory disk
@@ -34,10 +59,10 @@
 
 # Debugging options
 options        DIAGNOSTIC      # extra kernel sanity checking
-#options       DEBUG           # extra kernel debugging support
+options        DEBUG           # extra kernel debugging support
+options         LOCKDEBUG       # expensive locking checks/support
 #options       USERCONF        # userconf(4) support
-#options       SYSCTL_INCLUDE_DESCR    # Include sysctl descriptions in kernel
-#options       PMAP_DEBUG
+options        SYSCTL_INCLUDE_DESCR    # Include sysctl descriptions in kernel
 options        DDB             # kernel dynamic debugger
 options        DDB_HISTORY_SIZE=100 # enable history editing in DDB
 makeoptions    DEBUG="-g"      # compile full symbol table

----------------------- cut here -----------------------


Build and run on Ubiquiti Edgerouter Lite (Erlite3).

>Fix: