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CVS: cvs.openbsd.org: src

Module name:	src
Changes by:	miod_(_at_)_cvs_(_dot_)_openbsd_(_dot_)_org	2002/05/16 01:37:44

Modified files:
	sys/arch/vax/conf: files.vax 
	sys/arch/vax/vax: db_disasm.c db_disasm.h machdep.c trap.c 
Added files:
	sys/arch/vax/vax: opcodes.c 

Log message:
Fix a long standing problem on vax: on "arithmetic fault" exceptions,
we schedule a SIGFPE signal delivery to the faulting process.

However, arithmetic faults come in two flavors: "traps" that are "regular"
exceptions, and "faults" that are restartable exceptions.
In the "fault" case, the frame pc points to the faulting instruction, instead
of the next instruction, in case we could save the world by tweaking memory
and make the instruction not fault again when restarted.

In practice, this led to processes blocked in a SIGFPE loop madness.

To avoid this, add a skip_opcode() routine to compute the address of the
next opcode, effectively skipping the offending instruction ; this routine
is a very stripped-down db_disasm().

While there, enhance the ddb disassembler to correctly recognize and
disassemble two-byte opcodes.

ok hugh@, deraadt@