linux-kernel - [PATCH 3.16 078/148] powerpc: Allow 64bit VDSO __kernel_sync

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Message-ID: <lsq.1581185940.696641548@decadent.org.uk>
Date:   Sat, 08 Feb 2020 18:20:17 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Alastair D'Silva" <alastair@...ilva.org>,
        "Michael Ellerman" <mpe@...erman.id.au>
Subject: [PATCH 3.16 078/148] powerpc: Allow 64bit VDSO __kernel_sync_dicache
 to work across ranges >4GB

3.16.82-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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

commit f9ec11165301982585e5e5f606739b5bae5331f3 upstream.

When calling __kernel_sync_dicache 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>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/20191104023305.9581-3-alastair@au1.ibm.com
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/powerpc/kernel/vdso64/cacheflush.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/powerpc/kernel/vdso64/cacheflush.S
+++ b/arch/powerpc/kernel/vdso64/cacheflush.S
@@ -39,7 +39,7 @@ V_FUNCTION_BEGIN(__kernel_sync_dicache)
 	subf	r8,r6,r4		/* compute length */
 	add	r8,r8,r5		/* ensure we get enough */
 	lwz	r9,CFG_DCACHE_LOGBLOCKSZ(r10)
-	srw.	r8,r8,r9		/* compute line count */
+	srd.	r8,r8,r9		/* compute line count */
 	crclr	cr0*4+so
 	beqlr				/* nothing to do? */
 	mtctr	r8
@@ -56,7 +56,7 @@ V_FUNCTION_BEGIN(__kernel_sync_dicache)
 	subf	r8,r6,r4		/* compute length */
 	add	r8,r8,r5
 	lwz	r9,CFG_ICACHE_LOGBLOCKSZ(r10)
-	srw.	r8,r8,r9		/* compute line count */
+	srd.	r8,r8,r9		/* compute line count */
 	crclr	cr0*4+so
 	beqlr				/* nothing to do? */
 	mtctr	r8