sparc64: Convert copy_in_user to accurate exception reporting.

Report the exact number of bytes which have not been successfully
copied when an exception occurs, using the running remaining length.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/lib/copy_in_user.S

@@ -9,18 +9,33 @@
 
 #define XCC xcc
 
-#define EX(x,y)			\
+#define EX(x,y,z)		\
 98:	x,y;			\
 	.section __ex_table,"a";\
 	.align 4;		\
-	.word 98b, __retl_mone;	\
+	.word 98b, z;		\
 	.text;			\
 	.align 4;
 
+#define EX_O4(x,y) EX(x,y,__retl_o4_plus_8)
+#define EX_O2_4(x,y) EX(x,y,__retl_o2_plus_4)
+#define EX_O2_1(x,y) EX(x,y,__retl_o2_plus_1)
+
 	.register	%g2,#scratch
 	.register	%g3,#scratch
 
 	.text
+__retl_o4_plus_8:
+	add	%o4, %o2, %o4
+	retl
+	 add	%o4, 8, %o0
+__retl_o2_plus_4:
+	retl
+	 add	%o2, 4, %o0
+__retl_o2_plus_1:
+	retl
+	 add	%o2, 1, %o0
+
 	.align	32
 
 	/* Don't try to get too fancy here, just nice and
@@ -45,8 +60,8 @@ ENTRY(___copy_in_user)	/* %o0=dst, %o1=src, %o2=len */
 	andn		%o2, 0x7, %o4
 	and		%o2, 0x7, %o2
 1:	subcc		%o4, 0x8, %o4
-	EX(ldxa [%o1] %asi, %o5)
-	EX(stxa %o5, [%o0] %asi)
+	EX_O4(ldxa [%o1] %asi, %o5)
+	EX_O4(stxa %o5, [%o0] %asi)
 	add		%o1, 0x8, %o1
 	bgu,pt		%XCC, 1b
 	 add		%o0, 0x8, %o0
@@ -54,8 +69,8 @@ ENTRY(___copy_in_user)	/* %o0=dst, %o1=src, %o2=len */
 	be,pt		%XCC, 1f
 	 nop
 	sub		%o2, 0x4, %o2
-	EX(lduwa [%o1] %asi, %o5)
-	EX(stwa %o5, [%o0] %asi)
+	EX_O2_4(lduwa [%o1] %asi, %o5)
+	EX_O2_4(stwa %o5, [%o0] %asi)
 	add		%o1, 0x4, %o1
 	add		%o0, 0x4, %o0
 1:	cmp		%o2, 0
@@ -71,8 +86,8 @@ ENTRY(___copy_in_user)	/* %o0=dst, %o1=src, %o2=len */
 
 82:
 	subcc		%o2, 4, %o2
-	EX(lduwa [%o1] %asi, %g1)
-	EX(stwa %g1, [%o0] %asi)
+	EX_O2_4(lduwa [%o1] %asi, %g1)
+	EX_O2_4(stwa %g1, [%o0] %asi)
 	add		%o1, 4, %o1
 	bgu,pt		%XCC, 82b
 	 add		%o0, 4, %o0
@@ -83,8 +98,8 @@ ENTRY(___copy_in_user)	/* %o0=dst, %o1=src, %o2=len */
 	.align	32
 90:
 	subcc		%o2, 1, %o2
-	EX(lduba [%o1] %asi, %g1)
-	EX(stba %g1, [%o0] %asi)
+	EX_O2_1(lduba [%o1] %asi, %g1)
+	EX_O2_1(stba %g1, [%o0] %asi)
 	add		%o1, 1, %o1
 	bgu,pt		%XCC, 90b
 	 add		%o0, 1, %o0