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

The upstream commit:
22e9c88d486a ("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>

diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 3280953a82cf63c4372735762a09804fd9c21677..09af857ca09978e4514e1fa1a87c2f46ef2d3af0 100644 (file)
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -134,7 +134,7 @@ _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
@@ -190,7 +190,7 @@ _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