CVS commit: [netbsd-11] src/sys/arch/vax/vax

["matthew green" <mrg%netbsd.org@localhost>]

Module Name:    src
Committed By:   mrg
Date:           Tue Feb 24 00:25:48 UTC 2026

Modified Files:
        src/sys/arch/vax/vax [netbsd-11]: db_machdep.c

Log Message:
properly mask the "number of arguments" word to avoid invalid output.

i had a system soft-hang with cc1plus waiting for memory, but there
is enough memory free now, but when i tried to "bt/a <cc1plus addr>"
i was getting an extremely large output (several megabytes before i
killed simh).

we fetch the argument count from a 32-bit space in the stack frame,
but it's only the bottom byte that matters, the other bytes should
always be zero for netbsd, as they're used by VMS.

mask the high bytes of this value before consuming it.

also, since we don't expect to see them, simply give up when we find
a "callg" instruction.  i did attempt to handle this, but since they
should not be present, and seeing one would indicate that an unexpected
stack write to that bit, handling it just leads to more faults as they
vax_ap pointer does not point to valid memory and triggers crash (ie,
back to db> prompt.)


To generate a diff of this commit:
cvs rdiff -u -r1.61 -r1.61.2.1 src/sys/arch/vax/vax/db_machdep.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.