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    Subject[ 054/110] powerpc: Fix parameter clobber in csum_partial_copy_generic()
    Date
    3.10-stable review patch.  If anyone has any objections, please let me know.

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

    From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

    commit d9813c3681a36774b254c0cdc9cce53c9e22c756 upstream.

    The csum_partial_copy_generic() uses register r7 to adjust the remaining
    bytes to process. Unfortunately, r7 also holds a parameter, namely the
    address of the flag to set in case of access exceptions while reading
    the source buffer. Lacking a quantum implementation of PowerPC, this
    commit instead uses register r9 to do the adjusting, leaving r7's
    pointer uncorrupted.

    Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Signed-off-by: Anton Blanchard <anton@samba.org>
    Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/powerpc/lib/checksum_64.S | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/arch/powerpc/lib/checksum_64.S
    +++ b/arch/powerpc/lib/checksum_64.S
    @@ -269,8 +269,8 @@ _GLOBAL(csum_partial_copy_generic)
    rldicl. r6,r3,64-1,64-2 /* r6 = (r3 & 0x3) >> 1 */
    beq .Lcopy_aligned

    - li r7,4
    - sub r6,r7,r6
    + li r9,4
    + sub r6,r9,r6
    mtctr r6

    1:



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