[POWERPC] 64bit FPSCR support

Forthcoming machines will extend the FPSCR to 64 bits.  We already
had a 64-bit save area for the FPSCR, but we need to use a new form
of the mtfsf instruction.  Fortunately this new form is decoded as
an ordinary mtfsf by existing 64-bit processors.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/fpu.S

@@ -72,7 +72,7 @@ _GLOBAL(load_up_fpu)
 	std	r12,_MSR(r1)
 #endif
 	lfd	fr0,THREAD_FPSCR(r5)
-	mtfsf	0xff,fr0
+	MTFSF_L(fr0)
 	REST_32FPRS(0, r5)
 #ifndef CONFIG_SMP
 	subi	r4,r5,THREAD
@@ -127,7 +127,7 @@ _GLOBAL(giveup_fpu)
 
 _GLOBAL(cvt_fd)
 	lfd	0,THREAD_FPSCR(r5)	/* load up fpscr value */
-	mtfsf	0xff,0
+	MTFSF_L(0)
 	lfs	0,0(r3)
 	stfd	0,0(r4)
 	mffs	0
@@ -136,7 +136,7 @@ _GLOBAL(cvt_fd)
 
 _GLOBAL(cvt_df)
 	lfd	0,THREAD_FPSCR(r5)	/* load up fpscr value */
-	mtfsf	0xff,0
+	MTFSF_L(0)
 	lfd	0,0(r3)
 	stfs	0,0(r4)
 	mffs	0

arch/powerpc/kernel/vector.S

@@ -53,12 +53,12 @@ fpenable:
 	stfd	fr31,8(r1)
 	LDCONST(fr1, fpzero)
 	mffs	fr31
-	mtfsf	0xff,fr1
+	MTFSF_L(fr1)
 	blr
 
 fpdisable:
 	mtlr	r12
-	mtfsf	0xff,fr31
+	MTFSF_L(fr31)
 	lfd	fr31,8(r1)
 	lfd	fr1,16(r1)
 	lfd	fr0,24(r1)

include/asm-powerpc/reg.h

@@ -499,6 +499,19 @@
 #define MMCR0_PMC2_LOADMISSTIME	0x5
 #endif
 
+/*
+ * An mtfsf instruction with the L bit set. On CPUs that support this a
+ * full 64bits of FPSCR is restored and on other CPUs it is ignored.
+ *
+ * Until binutils gets the new form of mtfsf, hardwire the instruction.
+ */
+#ifdef CONFIG_PPC64
+#define MTFSF_L(REG) \
+	.long (0xfc00058e | ((0xff) << 17) | ((REG) << 11) | (1 << 25))
+#else
+#define MTFSF_L(REG)	mtfsf	0xff, (REG)
+#endif
+
 /* Processor Version Register (PVR) field extraction */
 
 #define PVR_VER(pvr)	(((pvr) >>  16) & 0xFFFF)	/* Version field */