Improve some ARMv7-A/M floating point register save time; Add floating point register save logic for ARMv7-A

1 files changed, 36 insertions, 13 deletions

diff --git a/nuttx/arch/arm/src/armv7-a/arm_saveusercontext.S b/nuttx/arch/arm/src/armv7-a/arm_saveusercontext.S
index 427a08765..bdf16a7a9 100644
--- a/nuttx/arch/arm/src/armv7-a/arm_saveusercontext.S
+++ b/nuttx/arch/arm/src/armv7-a/arm_saveusercontext.S
@@ -68,24 +68,23 @@
  * Public Functions
  ****************************************************************************/
 
+	.text
+
 /****************************************************************************
  * Name: up_saveusercontext
  ****************************************************************************/
 
-	.text
 	.globl	up_saveusercontext
 	.type	up_saveusercontext, function
+
 up_saveusercontext:
-	/* On entry, a1 (r0) holds address of struct xcptcontext.
-	 * Offset to the user region.
-	 */
 
-	/* Make sure that the return value will be non-zero (the
-	 * value of the other volatile registers don't matter --
-	 * r1-r3, ip).  This function is called throught the
-	 * normal C calling conventions and the values of these
-	 * registers cannot be assumed at the point of setjmp
-	 * return.
+	/* On entry, a1 (r0) holds address of struct xcptcontext */
+
+	/* Make sure that the return value will be non-zero (the value of the
+	 * other volatile registers don't matter -- r1-r3, ip).  This function
+	 * is called through the normal C calling conventions and the values of
+	 * these registers cannot be assumed at the point of setjmp return.
 	 */
 
 	mov		ip, #1
@@ -104,14 +103,38 @@ up_saveusercontext:
 	add		r1, r0, #(4*REG_CPSR)
 	str		r2, [r1]
 
-	/* Finally save the return address as the PC so that we
-	 * return to the exit from this function.
+	/* Save the return address as the PC so that we return to the exit from
+	 * this function.
 	 */
 
 	add		r1, r0, #(4*REG_PC)
 	str		lr, [r1]
 
-	/* Return 0 */
+	/* Save the floating point registers.
+	 * REVISIT:  Not all of the floating point registers need to be saved.
+	 * Some are volatile and need not be preserved across functions calls.
+	 * But right now, I can't find the definitive list of the volatile
+	 * floating point registers.
+	 */
+
+#ifdef CONFIG_ARCH_FPU
+	add		r1, r0, #(4*REG_S0)		/* R1=Address of FP register storage */
+
+	/* Store all floating point registers.  Registers are stored in numeric order,
+	 * s0, s1, ... in increasing address order.
+	 */
+
+	vstmia	r1!, {s0-s31}			/* Save the full FP context */
+
+	/* Store the floating point control and status register.  At the end of the
+	 * vstmia, r1 will point to the FPCSR storage location.
+	 */
+
+	vmrs	r2, fpscr				/* Fetch the FPCSR */
+	str		r2, [r1], #4			/* Save the floating point control and status register */
+#endif
+
+	/* Return 0 now indicating that this return is not a context switch */
 
 	mov		r0, #0			/* Return value == 0 */
 	mov		pc, lr			/* Return */