linux-kernel - [PATCH v3 10/11] powerpc/8xx: Use SPRG2 instead of DAR for saving r3

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Message-Id: <20150203113818.6F9551A5F1C@localhost.localdomain>
Date:	Tue,  3 Feb 2015 12:38:18 +0100 (CET)
From:	Christophe Leroy <christophe.leroy@....fr>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>, scottwood@...escale.com
CC:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
Subject: [PATCH v3 10/11] powerpc/8xx: Use SPRG2 instead of DAR for saving r3

We now have SPRG2 available as in it not used anymore for saving CR, so we don't
need to crash DAR anymore for saving r3 for CPU6 ERRATA handling.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>

---
v2: no change
v3: no change

 arch/powerpc/kernel/head_8xx.S | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index e803ad0..ead6448 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -309,7 +309,7 @@ SystemCall:
 
 InstructionTLBMiss:
 #ifdef CONFIG_8xx_CPU6
-	mtspr	SPRN_DAR, r3
+	mtspr	SPRN_SPRG_SCRATCH2, r3
 #endif
 	EXCEPTION_PROLOG_0
 
@@ -362,8 +362,7 @@ InstructionTLBMiss:
 
 	/* Restore registers */
 #ifdef CONFIG_8xx_CPU6
-	mfspr	r3, SPRN_DAR
-	mtspr	SPRN_DAR, r11	/* Tag DAR */
+	mfspr	r3, SPRN_SPRG_SCRATCH2
 #endif
 	EXCEPTION_EPILOG_0
 	rfi
@@ -371,7 +370,7 @@ InstructionTLBMiss:
 	. = 0x1200
 DataStoreTLBMiss:
 #ifdef CONFIG_8xx_CPU6
-	mtspr	SPRN_DAR, r3
+	mtspr	SPRN_SPRG_SCRATCH2, r3
 #endif
 	EXCEPTION_PROLOG_0
 	mfcr	r10
@@ -441,7 +440,7 @@ DataStoreTLBMiss:
 
 	/* Restore registers */
 #ifdef CONFIG_8xx_CPU6
-	mfspr	r3, SPRN_DAR
+	mfspr	r3, SPRN_SPRG_SCRATCH2
 #endif
 	mtspr	SPRN_DAR, r11	/* Tag DAR */
 	EXCEPTION_EPILOG_0
-- 
2.1.0

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