in the window trap vectors were mixed up. All this did is cause unnecesary
traps and look wierd in traces. Superfluous traps happen a lot in normal
operation, so we are rather good at recovering from them.
2. Store the arguments for a ktr trace in the right place.
3. Use a generic trap vector for breakpoints. It should not be special.
4. Save the frame pointer in the trap frame for kernel traps if DDB is compiled
in, otherwsie we don't save the out registers for kernel traps and stack
traces can't go through nested traps.
5. Apply the same fix to the return from kernel mode trap code as for user
mode traps. Ensure that the window we're returning to is the same one
that we restore to by fiddling the cwp in the saved tstate. This requires
that we transfer the values loaded from the trap frame into alternate
globals before restore-ing, but doing so is not very expensive and not
worth worrying about. Not changing the saved cwp can result in the register
values magically changing on return from traps if we happen to have slept
and the windows don't work out exactly the same. Fix the trace just before
the retry to account for different register usage.
6. Use a SET macro for loading address constants rather than a variation of
set and setx. set only works for 32 bit constants, while setx works for
64 bit constants as well, but produces bloated code when unnecessary.
Gas always generates the canonical 2 register, 6 instruction form, even
when it could be optimized; set uses 1 register and 2 instructions. At
the moment we assume that the kernel binary is below 4GB so set is
always sufficient, but the macro allows it to be configured. Note that
this has nothing to do with 32 vs. 64 bit address space, it only applies
to addresses of symbols which are known at compile/link time.
Submitted by: tmm (6)
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