linux-kernel - [PATCH v5 13/13] powerpc/40x: Don't save CR in SPRN_SPRG

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Message-Id: <019f314a98c107c4ca46e46c1cf402e9a44114a7.1590079969.git.christophe.leroy@csgroup.eu>
Date:   Thu, 21 May 2020 16:56:04 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, michal.simek@...inx.com,
        arnd@...db.de
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v5 13/13] powerpc/40x: Don't save CR in SPRN_SPRG_SCRATCH6

From: Christophe Leroy <christophe.leroy@....fr>

We have r12 available, use it to keep CR around and don't
save it in SPRN_SPRG_SCRATCH6.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/head_40x.S | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index b584e81f6d19..a22a8209971b 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -254,9 +254,8 @@ _ENTRY(saved_ksp_limit)
 	mtspr	SPRN_SPRG_SCRATCH1, r11
 	mtspr	SPRN_SPRG_SCRATCH3, r12
 	mtspr	SPRN_SPRG_SCRATCH4, r9
-	mfcr	r11
+	mfcr	r12
 	mfspr	r9, SPRN_PID
-	mtspr	SPRN_SPRG_SCRATCH6, r11
 	mtspr	SPRN_SPRG_SCRATCH5, r9
 	mfspr	r10, SPRN_DEAR		/* Get faulting address */
 
@@ -323,9 +322,8 @@ _ENTRY(saved_ksp_limit)
 	 * and call the heavyweights to help us out.
 	 */
 	mfspr	r9, SPRN_SPRG_SCRATCH5
-	mfspr	r11, SPRN_SPRG_SCRATCH6
 	mtspr	SPRN_PID, r9
-	mtcr	r11
+	mtcr	r12
 	mfspr	r9, SPRN_SPRG_SCRATCH4
 	mfspr	r12, SPRN_SPRG_SCRATCH3
 	mfspr	r11, SPRN_SPRG_SCRATCH1
@@ -341,9 +339,8 @@ _ENTRY(saved_ksp_limit)
 	mtspr	SPRN_SPRG_SCRATCH1, r11
 	mtspr	SPRN_SPRG_SCRATCH3, r12
 	mtspr	SPRN_SPRG_SCRATCH4, r9
-	mfcr	r11
+	mfcr	r12
 	mfspr	r9, SPRN_PID
-	mtspr	SPRN_SPRG_SCRATCH6, r11
 	mtspr	SPRN_SPRG_SCRATCH5, r9
 	mfspr	r10, SPRN_SRR0		/* Get faulting address */
 
@@ -410,9 +407,8 @@ _ENTRY(saved_ksp_limit)
 	 * and call the heavyweights to help us out.
 	 */
 	mfspr	r9, SPRN_SPRG_SCRATCH5
-	mfspr	r11, SPRN_SPRG_SCRATCH6
 	mtspr	SPRN_PID, r9
-	mtcr	r11
+	mtcr	r12
 	mfspr	r9, SPRN_SPRG_SCRATCH4
 	mfspr	r12, SPRN_SPRG_SCRATCH3
 	mfspr	r11, SPRN_SPRG_SCRATCH1
@@ -556,9 +552,8 @@ finish_tlb_load:
 	/* Done...restore registers and get out of here.
 	*/
 	mfspr	r9, SPRN_SPRG_SCRATCH5
-	mfspr	r11, SPRN_SPRG_SCRATCH6
 	mtspr	SPRN_PID, r9
-	mtcr	r11
+	mtcr	r12
 	mfspr	r9, SPRN_SPRG_SCRATCH4
 	mfspr	r12, SPRN_SPRG_SCRATCH3
 	mfspr	r11, SPRN_SPRG_SCRATCH1
-- 
2.25.0