Re-organise the code which manages the owner of the FP state (fpcurproc).

The old code was spread out through the machdep code and was sloppy about
enabling and disabling the FEN bit (which controls access to the FP
register set). This caused a DIAGNOSTIC warning "DANGER WILL ROBINSON:
FEN SET IN cpu_fork!" sometimes when operating under high loads and could
conceivably lead to processes getting incorrect FP results.

The new code is much more strict about the FEN bit and makes sure that
*only* fpcurproc ever has it enabled. This also allows us to remove a
section of code from the exception_return path which might improve
performance marginally.

Reviewed by: gallatin

1 files changed, 4 insertions, 0 deletions

diff --git a/sys/alpha/include/cpu.h b/sys/alpha/include/cpu.h
index cddefe1..b9ff12d 100644
--- a/sys/alpha/include/cpu.h
+++ b/sys/alpha/include/cpu.h
@@ -148,6 +148,10 @@ void	XentSys __P((u_int64_t, u_int64_t, u_int64_t));		/* MAGIC */
 void	XentUna __P((u_int64_t, u_int64_t, u_int64_t));		/* MAGIC */
 void	alpha_init __P((u_long, u_long, u_long, u_long, u_long));
 int	alpha_pa_access __P((u_long));
+void	alpha_fpstate_check __P((struct proc *p));
+void	alpha_fpstate_save __P((struct proc *p, int write));
+void	alpha_fpstate_drop __P((struct proc *p));
+void	alpha_fpstate_switch __P((struct proc *p));
 void	ast __P((struct trapframe *));
 int	badaddr	__P((void *, size_t));
 int	badaddr_read __P((void *, size_t, void *));