linux-kernel - [PATCH 2/4] powerpc/8xx: Fix TLB Miss exceptions with CONFIG

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Date:   Sat, 10 Oct 2020 15:14:33 +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>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 2/4] powerpc/8xx: Fix TLB Miss exceptions with CONFIG_SWAP

When CONFIG_SWAP is set, _PAGE_ACCESSED gets ANDed with
_PAGE_PRESENT. But during several changes of _PAGE_ACCESSED value,
this operation which is based on bit rotation has been forgotten.

As of today it doesn't work.

Update to the rotation to the correct number of bits.

Fixes: 5f356497c384 ("powerpc/8xx: remove unused _PAGE_WRITETHRU")
Fixes: e0a8e0d90a9f ("powerpc/8xx: Handle PAGE_USER via APG bits")
Fixes: 5b2753fc3e8a ("powerpc/8xx: Implementation of PAGE_EXEC")
Cc: stable@...r.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/head_8xx.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 32d85387bdc5..83101c5888e3 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -239,7 +239,7 @@ InstructionTLBMiss:
 	mtspr	SPRN_MI_TWC, r11
 #endif
 #ifdef CONFIG_SWAP
-	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
+	rlwinm	r11, r10, 32-7, _PAGE_PRESENT
 	and	r11, r11, r10
 	rlwimi	r10, r11, 0, _PAGE_PRESENT
 #endif
@@ -317,7 +317,7 @@ DataStoreTLBMiss:
 	 * r10 = (r10 & ~PRESENT) | r11;
 	 */
 #ifdef CONFIG_SWAP
-	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
+	rlwinm	r11, r10, 32-7, _PAGE_PRESENT
 	and	r11, r11, r10
 	rlwimi	r10, r11, 0, _PAGE_PRESENT
 #endif
-- 
2.25.0