Subject: [PATCH v4 07/21] powerpc/8xx: DataAccess exception not generated by MPC8xx

From: Christophe Leroy <[email-masked]>
Date: Fri, 19 Sep 2014 10:36:07 +0200 (CEST)

DataAccess exception is never generated by MPC8xx so do the job directly where
it is used to avoid an unnecessary branching.

Signed-off-by: Christophe Leroy <[email-masked]>

---
Changes in v2:
- None

Changes in v3:
- arch/powerpc/mm/fault.c uses the vector number, so make sure it understands
the new ones.

Changes in v4:
- Removing the change to mm/fault.c, faking the exception id to make mm/fault
think it comes from DataAccess.

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index a535576..570c1ee 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -219,19 +219,10 @@ MachineCheck:
 	EXC_XFER_STD(0x200, machine_check_exception)
 
 /* Data access exception.
- * This is "never generated" by the MPC8xx.  We jump to it for other
- * translation errors.
+ * This is "never generated" by the MPC8xx.
  */
 	. = 0x300
 DataAccess:
-	EXCEPTION_PROLOG
-	mfspr	r10,SPRN_DSISR
-	stw	r10,_DSISR(r11)
-	mr	r5,r10
-	mfspr	r4,SPRN_DAR
-	li	r10,0x00f0
-	mtspr	SPRN_DAR,r10	/* Tag DAR, to be used in DTLB Error */
-	EXC_XFER_LITE(0x300, handle_page_fault)
 
 /* Instruction access exception.
  * This is "never generated" by the MPC8xx.
@@ -491,7 +482,15 @@ DataTLBError:
 	beq-	FixupDAR	/* must be a buggy dcbX, icbi insn. */
 DARFixed:/* Return from dcbx instruction bug workaround */
 	EXCEPTION_EPILOG_0
-	b	DataAccess
+	EXCEPTION_PROLOG
+	mfspr	r10,SPRN_DSISR
+	stw	r10,_DSISR(r11)
+	mr	r5,r10
+	mfspr	r4,SPRN_DAR
+	li	r10,0x00f0
+	mtspr	SPRN_DAR,r10	/* Tag DAR, to be used in DTLB Error */
+	/* 0x300 is DataAccess exception, needed by bad_page_fault() */
+	EXC_XFER_LITE(0x300, handle_page_fault)
 
 	EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
 	EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
-- 
2.1.0