linux-kernel - [PATCH v3 07/21] powerpc/8xx: DataAccess exception not generated by MPC8xx

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Message-Id: <20140917163658.22F031AB036@localhost.localdomain>
Date:	Wed, 17 Sep 2014 18:36:58 +0200 (CEST)
From:	Christophe Leroy <christophe.leroy@....fr>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>
CC:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>,
	scottwood@...escale.com
Subject: [PATCH v3 07/21] powerpc/8xx: DataAccess exception not generated by MPC8xx

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 <christophe.leroy@....fr>

---
Changes in v2:
- None

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

 arch/powerpc/kernel/head_8xx.S | 23 ++++++++++-------------
 arch/powerpc/mm/fault.c        |  1 +
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 845abf8..5f04d5f 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -219,19 +219,9 @@ 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)
+	EXCEPTION(0x300, DataAccess, unknown_exception, EXC_XFER_STD)
 
 /* Instruction access exception.
  * This is "never generated" by the MPC8xx.
@@ -489,7 +479,14 @@ 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 */
+	EXC_XFER_LITE(0x1400, handle_page_fault)
 
 	EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
 	EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 4d63c96..adc084b 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -521,6 +521,7 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
 	switch (regs->trap) {
 	case 0x300:
 	case 0x380:
+	case 0x1400:
 		printk(KERN_ALERT "Unable to handle kernel paging request for "
 			"data at address 0x%08lx\n", regs->dar);
 		break;
-- 
2.1.0

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