powerpc: Rename thread_struct.fs to addr_limit

It's called 'fs' for historical reasons, it's named after the x86 'FS'
register. But we don't have to use that name for the member of
thread_struct, and in fact arch/x86 doesn't even call it 'fs' anymore.

So rename it to 'addr_limit', which better reflects what it's used
for, and is also the name used on other arches.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/processor.h

@@ -249,7 +249,7 @@ struct thread_struct {
 	unsigned long	ksp_vsid;
 #endif
 	struct pt_regs	*regs;		/* Pointer to saved register state */
-	mm_segment_t	fs;		/* for get_fs() validation */
+	mm_segment_t	addr_limit;	/* for get_fs() validation */
 #ifdef CONFIG_BOOKE
 	/* BookE base exception scratch space; align on cacheline */
 	unsigned long	normsave[8] ____cacheline_aligned;
@@ -379,7 +379,7 @@ struct thread_struct {
 #define INIT_THREAD { \
 	.ksp = INIT_SP, \
 	.ksp_limit = INIT_SP_LIMIT, \
-	.fs = KERNEL_DS, \
+	.addr_limit = KERNEL_DS, \
 	.pgdir = swapper_pg_dir, \
 	.fpexc_mode = MSR_FE0 | MSR_FE1, \
 	SPEFSCR_INIT \
@@ -388,7 +388,7 @@ struct thread_struct {
 #define INIT_THREAD  { \
 	.ksp = INIT_SP, \
 	.regs = (struct pt_regs *)INIT_SP - 1, /* XXX bogus, I think */ \
-	.fs = KERNEL_DS, \
+	.addr_limit = KERNEL_DS, \
 	.fpexc_mode = 0, \
 	.ppr = INIT_PPR, \
 	.fscr = FSCR_TAR | FSCR_EBB \

arch/powerpc/include/asm/uaccess.h

@@ -30,8 +30,8 @@
 #endif
 
 #define get_ds()	(KERNEL_DS)
-#define get_fs()	(current->thread.fs)
-#define set_fs(val)	(current->thread.fs = (val))
+#define get_fs()	(current->thread.addr_limit)
+#define set_fs(val)	(current->thread.addr_limit = (val))
 
 #define segment_eq(a, b)	((a).seg == (b).seg)