linux-kernel - [PATCH] powerpc: Allow flush_(inval_)dcache

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Message-Id: <20190815045543.16325-1-alastair@au1.ibm.com>
Date:   Thu, 15 Aug 2019 14:55:42 +1000
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     alastair@...ilva.org, mpe@...erman.id.au
Cc:     stable@...r.kernel.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Allison Randal <allison@...utok.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH] powerpc: Allow flush_(inval_)dcache_range to work across ranges >4GB

From: Alastair D'Silva <alastair@...ilva.org>

Heads Up: This patch cannot be submitted to Linus's tree, as the affected
assembler functions have already been converted to C.

When calling flush_(inval_)dcache_range with a size >4GB, we were masking
off the upper 32 bits, so we would incorrectly flush a range smaller
than intended.

This patch replaces the 32 bit shifts with 64 bit ones, so that
the full size is accounted for.

Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
---
 arch/powerpc/kernel/misc_64.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 1ad4089dd110..d4d096f80f4b 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -130,7 +130,7 @@ _GLOBAL_TOC(flush_dcache_range)
 	subf	r8,r6,r4		/* compute length */
 	add	r8,r8,r5		/* ensure we get enough */
 	lwz	r9,DCACHEL1LOGBLOCKSIZE(r10)	/* Get log-2 of dcache block size */
-	srw.	r8,r8,r9		/* compute line count */
+	srd.	r8,r8,r9		/* compute line count */
 	beqlr				/* nothing to do? */
 	mtctr	r8
 0:	dcbst	0,r6
@@ -148,7 +148,7 @@ _GLOBAL(flush_inval_dcache_range)
 	subf	r8,r6,r4		/* compute length */
 	add	r8,r8,r5		/* ensure we get enough */
 	lwz	r9,DCACHEL1LOGBLOCKSIZE(r10)/* Get log-2 of dcache block size */
-	srw.	r8,r8,r9		/* compute line count */
+	srd.	r8,r8,r9		/* compute line count */
 	beqlr				/* nothing to do? */
 	sync
 	isync
-- 
2.21.0