svn commit: r187867 - in head/sys/amd64: amd64 include

[John Baldwin]

Author: jhb
Date: Wed Jan 28 20:35:16 2009
New Revision: 187867
URL: http://svn.freebsd.org/changeset/base/187867

Log:
  Use a different value for the initial control word for the FPU state for
  32-bit processes.  The value matches the initial setting used by
  FreeBSD/i386.  Otherwise, 32-bit binaries using floating point would use
  a slightly different initial state when run on FreeBSD/amd64.
  
  MFC after:	1 week

Modified:
  head/sys/amd64/amd64/fpu.c
  head/sys/amd64/include/fpu.h

Modified: head/sys/amd64/amd64/fpu.c
==============================================================================
--- head/sys/amd64/amd64/fpu.c	Wed Jan 28 20:06:02 2009	(r187866)
+++ head/sys/amd64/amd64/fpu.c	Wed Jan 28 20:35:16 2009	(r187867)
@@ -391,6 +391,7 @@ fpudna()
 {
 	struct pcb *pcb;
 	register_t s;
+	u_short control;
 
 	if (PCPU_GET(fpcurthread) == curthread) {
 		printf("fpudna: fpcurthread == curthread %d times\n",
@@ -421,6 +422,10 @@ fpudna()
 		 * explicitly load sanitized registers.
 		 */
 		fxrstor(&fpu_cleanstate);
+		if (pcb->pcb_flags & PCB_32BIT) {
+			control = __INITIAL_FPUCW_I386__;
+			fldcw(&control);
+		}
 		pcb->pcb_flags |= PCB_FPUINITDONE;
 	} else
 		fxrstor(&pcb->pcb_save);

Modified: head/sys/amd64/include/fpu.h
==============================================================================
--- head/sys/amd64/include/fpu.h	Wed Jan 28 20:06:02 2009	(r187866)
+++ head/sys/amd64/include/fpu.h	Wed Jan 28 20:35:16 2009	(r187867)
@@ -92,6 +92,7 @@ struct  savefpu {
  * SSE2 based math.  For FreeBSD/amd64, we go with the default settings.
  */
 #define	__INITIAL_FPUCW__	0x037F
+#define	__INITIAL_FPUCW_I386__	0x127F
 #define	__INITIAL_MXCSR__	0x1F80
 #define	__INITIAL_MXCSR_MASK__	0xFFBF