Geode CPU does not support SSE, so MXCSR does not exists there. As

our i386 compiler does not generate SSE instructions by default,
it is not strictly necessary to save MXCSR content between setjmp(3)
and longjmp(3).  We do not want to end supporting such old processors
now.  Remove the stmxcsr and ldmxcsr instructions from libc.
reported by Johan Huldtgren; OK jsg@ kettenis@

4 files changed, 5 insertions, 12 deletions

diff --git a/lib/libc/arch/i386/gen/_setjmp.S b/lib/libc/arch/i386/gen/_setjmp.S
index f1f5d99fd71..08030e2d9cb 100644
--- a/lib/libc/arch/i386/gen/_setjmp.S
+++ b/lib/libc/arch/i386/gen/_setjmp.S
@@ -1,4 +1,4 @@
-/* $OpenBSD: _setjmp.S,v 1.8 2020/12/06 18:13:15 bluhm Exp $ */
+/* $OpenBSD: _setjmp.S,v 1.9 2020/12/13 21:21:32 bluhm Exp $ */
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
@@ -63,7 +63,6 @@ ENTRY(_setjmp)
 	movl	%ecx,(_JB_EBP * 4)(%eax)
 	movl	%esi,(_JB_ESI * 4)(%eax)
 	movl	%edi,(_JB_EDI * 4)(%eax)
-	stmxcsr	(_JB_MXCSR * 4)(%eax)
 	fnstcw	(_JB_FCW * 4)(%eax)
 	xorl	%eax,%eax
 	ret
@@ -75,7 +74,6 @@ ENTRY(_longjmp)
 	addl	$__jmpxor-1b,%ecx	# load cookie address
 	movl	4(%esp),%edx		# parameter, pointer to env
 	movl	8(%esp),%eax		# parameter, val
-	ldmxcsr	(_JB_MXCSR * 4)(%edx)
 	fldcw	(_JB_FCW * 4)(%edx)
 	movl	(_JB_EBX * 4)(%edx),%ebx
 	movl	(_JB_ESP * 4)(%edx),%esi
diff --git a/lib/libc/arch/i386/gen/setjmp.S b/lib/libc/arch/i386/gen/setjmp.S
index 47104a3c8b8..9dbb4ffafc1 100644
--- a/lib/libc/arch/i386/gen/setjmp.S
+++ b/lib/libc/arch/i386/gen/setjmp.S
@@ -1,4 +1,4 @@
-/* $OpenBSD: setjmp.S,v 1.13 2020/12/06 18:13:15 bluhm Exp $ */
+/* $OpenBSD: setjmp.S,v 1.14 2020/12/13 21:21:32 bluhm Exp $ */
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
@@ -78,7 +78,6 @@ ENTRY(setjmp)
 	movl	8(%edx),%edx		# load eip cookie over cookie address
 	xorl	0(%esp),%edx		# caller address
 	movl	%edx,(_JB_EIP * 4)(%ecx)
-	stmxcsr	(_JB_MXCSR * 4)(%ecx)
 	fnstcw	(_JB_FCW * 4)(%ecx)
 	xorl	%eax,%eax
 	ret
@@ -97,7 +96,6 @@ ENTRY(longjmp)
 
 	movl	4(%esp),%edx		# parameter, pointer to env
 	movl	8(%esp),%eax		# parameter, val
-	ldmxcsr	(_JB_MXCSR * 4)(%edx)
 	fldcw	(_JB_FCW * 4)(%edx)
 	movl	(_JB_EBX * 4)(%edx),%ebx
 	movl	(_JB_ESP * 4)(%edx),%esi
diff --git a/lib/libc/arch/i386/gen/sigsetjmp.S b/lib/libc/arch/i386/gen/sigsetjmp.S
index 935d1514230..2c2013257bf 100644
--- a/lib/libc/arch/i386/gen/sigsetjmp.S
+++ b/lib/libc/arch/i386/gen/sigsetjmp.S
@@ -1,4 +1,4 @@
-/* $OpenBSD: sigsetjmp.S,v 1.12 2020/12/06 18:13:15 bluhm Exp $ */
+/* $OpenBSD: sigsetjmp.S,v 1.13 2020/12/13 21:21:32 bluhm Exp $ */
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
@@ -67,7 +67,6 @@ ENTRY(sigsetjmp)
 	movl	4(%edx),%edx		# load eip cookie over cookie address
 	xorl	0(%esp),%edx
 	movl	%edx,(_JB_EIP * 4)(%ecx)
-	stmxcsr	(_JB_MXCSR * 4)(%ecx)
 	fnstcw	(_JB_FCW * 4)(%ecx)
 	xorl	%eax,%eax
 	ret
@@ -91,7 +90,6 @@ ENTRY(siglongjmp)
 
 	movl	4(%esp),%edx		# reload in case sigprocmask failed
 	movl	8(%esp),%eax		# parameter, val
-	ldmxcsr	(_JB_MXCSR * 4)(%edx)
 	fldcw	(_JB_FCW * 4)(%edx)
 	movl	(_JB_EBX * 4)(%edx),%ebx
 	movl	(_JB_ESP * 4)(%edx),%esi
diff --git a/sys/arch/i386/include/setjmp.h b/sys/arch/i386/include/setjmp.h
index d72d703d03b..b9c7867f9d2 100644
--- a/sys/arch/i386/include/setjmp.h
+++ b/sys/arch/i386/include/setjmp.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: setjmp.h,v 1.3 2020/12/06 15:31:30 bluhm Exp $	*/
+/*	$OpenBSD: setjmp.h,v 1.4 2020/12/13 21:21:32 bluhm Exp $	*/
 /*	$NetBSD: setjmp.h,v 1.1 1994/12/20 10:36:43 cgd Exp $	*/
 
 /*
@@ -13,7 +13,6 @@
 #define _JB_EDI		5
 #define _JB_SIGMASK	6
 #define _JB_SIGFLAG	7
-#define _JB_MXCSR	8
-#define _JB_FCW		9
+#define _JB_FCW		8
 
 #define _JBLEN		10	/* size, in longs, of a jmp_buf */