svn commit: r288492 - head/sys/arm/arm

[Konstantin Belousov]

Author: kib
Date: Fri Oct  2 13:25:59 2015
New Revision: 288492
URL: https://svnweb.freebsd.org/changeset/base/288492

Log:
  Do not set 'flush to zero' VFPSCR_FZ bit by default.  The correct
  implementation of IEEE 754 arithmetic depends on denormals operating
  correctly.  Both perl test suite and paranoia tripped over the
  setting.
  
  Reported by:	Stefan Parvu <sparvu at kronometrix.org>
  Discussed with:	andrew
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/arm/arm/machdep.c
  head/sys/arm/arm/vm_machdep.c

Modified: head/sys/arm/arm/machdep.c
==============================================================================
--- head/sys/arm/arm/machdep.c	Fri Oct  2 13:21:08 2015	(r288491)
+++ head/sys/arm/arm/machdep.c	Fri Oct  2 13:25:59 2015	(r288492)
@@ -1069,7 +1069,7 @@ init_proc0(vm_offset_t kstack)
 		(thread0.td_kstack + kstack_pages * PAGE_SIZE) - 1;
 	thread0.td_pcb->pcb_flags = 0;
 	thread0.td_pcb->pcb_vfpcpu = -1;
-	thread0.td_pcb->pcb_vfpstate.fpscr = VFPSCR_DN | VFPSCR_FZ;
+	thread0.td_pcb->pcb_vfpstate.fpscr = VFPSCR_DN;
 	thread0.td_frame = &proc0_tf;
 	pcpup->pc_curpcb = thread0.td_pcb;
 }

Modified: head/sys/arm/arm/vm_machdep.c
==============================================================================
--- head/sys/arm/arm/vm_machdep.c	Fri Oct  2 13:21:08 2015	(r288491)
+++ head/sys/arm/arm/vm_machdep.c	Fri Oct  2 13:25:59 2015	(r288492)
@@ -134,7 +134,7 @@ cpu_fork(register struct thread *td1, re
 	pcb2->pcb_regs.sf_sp = STACKALIGN(td2->td_frame);
 
 	pcb2->pcb_vfpcpu = -1;
-	pcb2->pcb_vfpstate.fpscr = VFPSCR_DN | VFPSCR_FZ;
+	pcb2->pcb_vfpstate.fpscr = VFPSCR_DN;
 
 	tf = td2->td_frame;
 	tf->tf_spsr &= ~PSR_C;