powerpc: Introduce toreal/fromreal assembly macros

On 32-bit platforms, these convert from kernel virtual addresses
to real (physical addresses), like tophys/tovirt but they use
the same register for the source and destination.  On 64-bit
platforms, they do nothing because the hardware ignores the top
two bits of the address in real mode.

These new macros are used in fpu.S now.

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

arch/powerpc/kernel/fpu.S

@@ -40,17 +40,17 @@ _GLOBAL(load_up_fpu)
  */
 #ifndef CONFIG_SMP
 	LOADBASE(r3, last_task_used_math)
-	tophys(r3,r3)
+	toreal(r3)
 	LDL	r4,OFF(last_task_used_math)(r3)
 	CMPI	0,r4,0
 	beq	1f
-	tophys(r4,r4)
+	toreal(r4)
 	addi	r4,r4,THREAD		/* want last_task_used_math->thread */
 	SAVE_32FPRS(0, r4)
 	mffs	fr0
 	stfd	fr0,THREAD_FPSCR(r4)
 	LDL	r5,PT_REGS(r4)
-	tophys(r5,r5)
+	toreal(r5)
 	LDL	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 	li	r10,MSR_FP|MSR_FE0|MSR_FE1
 	andc	r4,r4,r10		/* disable FP for previous task */
@@ -76,7 +76,7 @@ _GLOBAL(load_up_fpu)
 	REST_32FPRS(0, r5)
 #ifndef CONFIG_SMP
 	subi	r4,r5,THREAD
-	tovirt(r4,r4)
+	fromreal(r4)
 	STL	r4,OFF(last_task_used_math)(r3)
 #endif /* CONFIG_SMP */
 	/* restore registers and return */

include/asm-powerpc/ppc_asm.h

@@ -154,7 +154,7 @@ GLUE(.,name):
  *   loads the address of 'name' into 'rn'
  *
  * LOADBASE( rn, name )
- *   loads the address (less the low 16 bits) of 'name' into 'rn'
+ *   loads the address (possibly without the low 16 bits) of 'name' into 'rn'
  *   suitable for base+disp addressing
  */
 #ifdef __powerpc64__
@@ -166,10 +166,7 @@ GLUE(.,name):
 	ori	rn,rn,name##@l
 
 #define LOADBASE(rn,name)		\
-	.section .toc,"aw";		\
-1:	.tc	name[TC],name;		\
-	.previous;			\
-	ld	rn,1b@toc(r2)
+	ld	rn,name@got(r2)
 
 #define OFF(name)	0
 
@@ -278,30 +275,34 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601)
 
 
 #if defined(CONFIG_BOOKE)
+#define toreal(rd)
+#define fromreal(rd)
+
 #define tophys(rd,rs)				\
 	addis	rd,rs,0
 
 #define tovirt(rd,rs)				\
 	addis	rd,rs,0
 
 #elif defined(CONFIG_PPC64)
-/* PPPBBB - DRENG  If KERNELBASE is always 0xC0...,
- * Then we can easily do this with one asm insn. -Peter
- */
+#define toreal(rd)		/* we can access c000... in real mode */
+#define fromreal(rd)
+
 #define tophys(rd,rs)                           \
-        lis     rd,((KERNELBASE>>48)&0xFFFF);   \
-        rldicr  rd,rd,32,31;                    \
-        sub     rd,rs,rd
+	clrldi	rd,rs,2
 
 #define tovirt(rd,rs)                           \
-        lis     rd,((KERNELBASE>>48)&0xFFFF);   \
-        rldicr  rd,rd,32,31;                    \
-        add     rd,rs,rd
+	rotldi	rd,rs,16;			\
+	ori	rd,rd,((KERNELBASE>>48)&0xFFFF);\
+	rotldi	rd,rd,48
 #else
 /*
  * On APUS (Amiga PowerPC cpu upgrade board), we don't know the
  * physical base address of RAM at compile time.
  */
+#define toreal(rd)	tophys(rd,rd)
+#define fromreal(rd)	tovirt(rd,rd)
+
 #define tophys(rd,rs)				\
 0:	addis	rd,rs,-KERNELBASE@h;		\
 	.section ".vtop_fixup","aw";		\