Peter Wemm 19acc770c2 Pull the tier-2 card one last time and break the get/setcontext and
sigreturn() ABI and the signal context on the stack.

Make the trapframe (and its shadows in the ucontext and sigframe etc)
8 bytes larger in order to preserve 16 byte stack alignment for the
following C code calls.  I could have done some padding after the
trapframe was saved, but some of the C code still expects an argument of
'struct trapframe'.  Anyway, this gives me a spare field that can be used
to store things like 'partial trapframe' status or something else in
the future.

The runtime impact is fairly small, *except* for threaded apps and things
that decode contexts and the signal stack (eg: cvsup binary).  Signal
delivery isn't too badly affected because the kernel generates the
sigframe that sigreturn uses after the handler has been called.

The size of mcontext_t and struct sigframe hasn't changed.  Only
the last few fields (sc_eip etc) got moved a little and I eliminated
a spare field.  mc_len/sc_len did change location though so the
sanity checks there will still trap it.
2003-10-15 02:04:52 +00:00
..
2002-07-06 02:49:07 +00:00
2003-09-23 00:04:28 +00:00