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powerpc: Allow flush_(inval_)dcache_range to work across ranges >4GB

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The upstream commit:
22e9c88d48 ("powerpc/64: reuse PPC32 static inline flush_dcache_range()")
has a similar effect, but since it is a rewrite of the assembler to C, is
too invasive for stable. This patch is a minimal fix to address the issue in
assembler.

This patch applies cleanly to v5.2, v4.19 & v4.14.

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@d-silva.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alastair D'Silva 2019-08-21 10:19:27 +10:00 • committed by Greg Kroah-Hartman
commit 32df8a30b7
1 changed files with 2 additions and 2 deletions
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4
arch/powerpc/kernel/misc_64.S
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@ -135,7 +135,7 @@ _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
@ -153,7 +153,7 @@ _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