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.

1 files changed, 2 insertions, 2 deletions

diff --git a/sys/amd64/include/signal.h b/sys/amd64/include/signal.h
index 46b35ab..9aad84a 100644
--- a/sys/amd64/include/signal.h
+++ b/sys/amd64/include/signal.h
@@ -91,6 +91,7 @@ struct sigcontext {
 	long	sc_r15;
 	long	sc_trapno;
 	long	sc_addr;
+	long	sc_flags;
 	long	sc_err;
 	long	sc_rip;
 	long	sc_cs;
@@ -104,9 +105,8 @@ struct sigcontext {
 	 */
 	long	sc_fpformat;
 	long	sc_ownedfp;
-	long	sc_spare1[1];
 	long	sc_fpstate[64] __aligned(16);
-	long	sc_spare2[8];
+	long	sc_spare[8];
 };
 #endif /* __BSD_VISIBLE */