powerpc/6xx: Handle DABR match before calling do_page_fault

On legacy 6xx 32-bit procesors, we checked for the DABR match bit
in DSISR from do_page_fault(), in the middle of a pile of ifdef's
because all other CPU types do it in assembly prior to calling
do_page_fault. Fix that.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[mpe: Add #ifdef CONFIG_6xx]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/entry_32.S

@@ -586,7 +586,11 @@ ppc_swapcontext:
 handle_page_fault:
 	stw	r4,_DAR(r1)
 	addi	r3,r1,STACK_FRAME_OVERHEAD
+	andis.  r0,r5,DSISR_DABRMATCH@h
+#ifdef CONFIG_6xx
+	bne-    handle_dabr_fault
 	bl	do_page_fault
+#endif
 	cmpwi	r3,0
 	beq+	ret_from_except
 	SAVE_NVGPRS(r1)
@@ -599,6 +603,17 @@ handle_page_fault:
 	bl	bad_page_fault
 	b	ret_from_except_full
 
+#ifdef CONFIG_6xx
+	/* We have a data breakpoint exception - handle it */
+handle_dabr_fault:
+	SAVE_NVGPRS(r1)
+	lwz	r0,_TRAP(r1)
+	clrrwi	r0,r0,1
+	stw	r0,_TRAP(r1)
+	bl      do_break
+	b	ret_from_except_full
+#endif
+
 /*
  * This routine switches between two different tasks.  The process
  * state of one is saved on its kernel stack.  Then the state

arch/powerpc/mm/fault.c

@@ -242,15 +242,6 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
 		goto bail;
 	}
 
-#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE) || \
-      defined(CONFIG_PPC_BOOK3S_64) || defined(CONFIG_PPC_8xx))
-  	if (error_code & DSISR_DABRMATCH) {
-		/* breakpoint match */
-		do_break(regs, address, error_code);
-		goto bail;
-	}
-#endif
-
 	/* We restore the interrupt state now */
 	if (!arch_irq_disabled_regs(regs))
 		local_irq_enable();