powerpc/8xx: Split breakpoint exception

Breakpoint exception is big.

Split it to support future growth on exception prolog.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1dda3293d86d0f715b13b2633c95d2188a42a02c.1576916812.git.christophe.leroy@c-s.fr

arch/powerpc/kernel/head_8xx.S

@@ -490,14 +490,7 @@ DARFixed:/* Return from dcbx instruction bug workaround */
  * support of breakpoints and such.  Someday I will get around to
  * using them.
  */
-	. = 0x1c00
+do_databreakpoint:
-DataBreakpoint:
-	EXCEPTION_PROLOG_0
-	mfspr	r11, SPRN_SRR0
-	cmplwi	cr1, r11, (.Ldtlbie - PAGE_OFFSET)@l
-	cmplwi	cr7, r11, (.Litlbie - PAGE_OFFSET)@l
-	beq-	cr1, 11f
-	beq-	cr7, 11f
 	EXCEPTION_PROLOG_1
 	EXCEPTION_PROLOG_2
 	addi	r3,r1,STACK_FRAME_OVERHEAD
@@ -505,7 +498,15 @@ DataBreakpoint:
 	stw	r4,_DAR(r11)
 	mfspr	r5,SPRN_DSISR
 	EXC_XFER_STD(0x1c00, do_break)
-11:
+
+	. = 0x1c00
+DataBreakpoint:
+	EXCEPTION_PROLOG_0
+	mfspr	r11, SPRN_SRR0
+	cmplwi	cr1, r11, (.Ldtlbie - PAGE_OFFSET)@l
+	cmplwi	cr7, r11, (.Litlbie - PAGE_OFFSET)@l
+	cror	4*cr1+eq, 4*cr1+eq, 4*cr7+eq
+	bne	cr1, do_databreakpoint
 	mtcr	r10
 	mfspr	r10, SPRN_SPRG_SCRATCH0
 	mfspr	r11, SPRN_SPRG_SCRATCH1