Always call vfp_discard() on thread death, not just when the VFP is

enabled.  In vfp_discard(), if the state in the VFP hardware belongs to
the thread which is dying, NULL out pcpu fpcurthread to indicate the
state currently in the hardware belongs to nobody.

Submitted by:	Juergen Weiss
Pointy hat to:	me

3 files changed, 14 insertions, 15 deletions

diff --git a/sys/arm/arm/swtch.S b/sys/arm/arm/swtch.S
index 2703b03..d704823 100644
--- a/sys/arm/arm/swtch.S
+++ b/sys/arm/arm/swtch.S
@@ -124,14 +124,11 @@ ENTRY(cpu_throw)
 	 * r5 = newtd
 	 */
 
-	GET_PCPU(r7, r9)
-
-#ifdef VFP
-	fmrx	r0, fpexc		/* This thread is dying, if the VFP */
-	tst	r0, #(VFPEXC_EN)	/* is enabled, go shut it down */
-	blne	_C_LABEL(vfp_discard)	/* without preserving its state. */
+#ifdef VFP				/* This thread is dying, disable */
+	bl	_C_LABEL(vfp_discard)	/* VFP without preserving state. */
 #endif
 
+	GET_PCPU(r7, r9)
 	ldr	r7, [r5, #(TD_PCB)]		/* r7 = new thread's PCB */
   
 	/* Switch to lwp0 context */
diff --git a/sys/arm/arm/vfp.c b/sys/arm/arm/vfp.c
index d370da4..240ede3 100644
--- a/sys/arm/arm/vfp.c
+++ b/sys/arm/arm/vfp.c
@@ -229,21 +229,23 @@ vfp_store(struct vfp_state *vfpsave, boolean_t disable_vfp)
 }
 
 /*
- * If the VFP hardware is on, the current thread was using it but now that
- * thread is dying.  Turn off the VFP and set pcpu fpcurthread to 0, to indicate
- * that the VFP hardware state does not belong to any thread.   Called only from
- * cpu_throw(), so we don't have to worry about a context switch here.
+ * The current thread is dying.  If the state currently in the hardware belongs
+ * to the current thread, set fpcurthread to NULL to indicate that the VFP
+ * hardware state does not belong to any thread.  If the VFP is on, turn it off.
+ * Called only from cpu_throw(), so we don't have to worry about a context
+ * switch here.
  */
 void
-vfp_discard()
+vfp_discard(struct thread *td)
 {
 	u_int tmp;
 
+	if (PCPU_GET(fpcurthread) == td)
+		PCPU_SET(fpcurthread, NULL);
+
 	tmp = fmrx(VFPEXC);
-	if (tmp & VFPEXC_EN) {
+	if (tmp & VFPEXC_EN)
 		fmxr(VFPEXC, tmp & ~VFPEXC_EN);
-		PCPU_SET(fpcurthread, 0);
-	}
 }
 
 #endif
diff --git a/sys/arm/include/vfp.h b/sys/arm/include/vfp.h
index 9023821..befba18 100644
--- a/sys/arm/include/vfp.h
+++ b/sys/arm/include/vfp.h
@@ -129,7 +129,7 @@
 #ifndef LOCORE
 void    vfp_init(void);
 void    vfp_store(struct vfp_state *, boolean_t);
-void    vfp_discard(void);
+void    vfp_discard(struct thread *);
 #endif
 
 #endif