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/ucontext.h b/sys/amd64/include/ucontext.h
index 7e68dc1..ca2044c 100644
--- a/sys/amd64/include/ucontext.h
+++ b/sys/amd64/include/ucontext.h
@@ -55,6 +55,7 @@ typedef struct __mcontext {
 	__register_t	mc_r15;
 	__register_t	mc_trapno;
 	__register_t	mc_addr;
+	__register_t	mc_flags;
 	__register_t	mc_err;
 	__register_t	mc_rip;
 	__register_t	mc_cs;
@@ -70,12 +71,11 @@ typedef struct __mcontext {
 #define	_MC_FPOWNED_FPU		0x20001	/* FP state came from FPU */
 #define	_MC_FPOWNED_PCB		0x20002	/* FP state came from PCB */
 	long	mc_ownedfp;
-	long	mc_spare1[1];		/* align mc_fpstate to 16 bytes */
 	/*
 	 * See <machine/npx.h> for the internals of mc_fpstate[].
 	 */
 	long	mc_fpstate[64] __aligned(16);
-	long	mc_spare2[8];
+	long	mc_spare[8];
 } mcontext_t;
 
 #endif /* !_MACHINE_UCONTEXT_H_ */