linux-kernel - [PATCH v2 08/10] powerpc/603: let's handle PAGE

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Message-Id: <a811b67c722df3bd6bdbaaa77d2621b9b4825301.1550745320.git.christophe.leroy@c-s.fr>
Date:   Thu, 21 Feb 2019 10:38:00 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
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 v2 08/10] powerpc/603: let's handle PAGE_DIRTY directly

PAGE_DIRTY corresponds to the C bit. If writing on
a page for which the C bit is not set, a DataStoreTLBMiss
is generated. No need to check it in DataLoadTLBMiss.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/kernel/head_32.S | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 6db54425f1d9..b071f328b4b0 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -595,12 +595,10 @@ DataLoadTLBMiss:
 	stw	r0,0(r2)		/* update PTE (accessed bit) */
 	/* Convert linux-style PTE to low word of PPC-style PTE */
 	rlwinm	r1,r0,32-10,31,31	/* _PAGE_RW -> PP lsb */
-	rlwinm	r2,r0,32-7,31,31	/* _PAGE_DIRTY -> PP lsb */
-	and	r1,r1,r2		/* writable if _RW and _DIRTY */
 	rlwimi	r0,r0,32-1,30,30	/* _PAGE_USER -> PP msb */
 	rlwimi	r0,r0,32-1,31,31	/* _PAGE_USER -> PP lsb */
 	ori	r1,r1,0xe04		/* clear out reserved bits */
-	andc	r1,r0,r1		/* PP = user? (rw&dirty? 2: 3): 0 */
+	andc	r1,r0,r1		/* PP = user? rw? 2: 3: 0 */
 BEGIN_FTR_SECTION
 	rlwinm	r1,r1,0,~_PAGE_COHERENT	/* clear M (coherence not required) */
 END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
@@ -669,7 +667,7 @@ DataStoreTLBMiss:
 	lwz	r0,0(r2)		/* get linux-style pte */
 	andc.	r1,r1,r0		/* check access & ~permission */
 	bne-	DataAddressInvalid	/* return if access not permitted */
-	ori	r0,r0,_PAGE_ACCESSED|_PAGE_DIRTY
+	ori	r0,r0,_PAGE_ACCESSED
 	/*
 	 * NOTE! We are assuming this is not an SMP system, otherwise
 	 * we would need to update the pte atomically with lwarx/stwcx.
-- 
2.13.3