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    Subject[PATCH 4.19 118/134] powerpc/pseries/energy: Use OF accessor functions to read ibm,drc-indexes
    Date
    4.19-stable review patch.  If anyone has any objections, please let me know.

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

    From: Gautham R. Shenoy <ego@linux.vnet.ibm.com>

    commit ce9afe08e71e3f7d64f337a6e932e50849230fc2 upstream.

    In cpu_to_drc_index() in the case when FW_FEATURE_DRC_INFO is absent,
    we currently use of_read_property() to obtain the pointer to the array
    corresponding to the property "ibm,drc-indexes". The elements of this
    array are of type __be32, but are accessed without any conversion to
    the OS-endianness, which is buggy on a Little Endian OS.

    Fix this by using of_property_read_u32_index() accessor function to
    safely read the elements of the array.

    Fixes: e83636ac3334 ("pseries/drc-info: Search DRC properties for CPU indexes")
    Cc: stable@vger.kernel.org # v4.16+
    Reported-by: Pavithra R. Prakash <pavrampu@in.ibm.com>
    Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
    Reviewed-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
    [mpe: Make the WARN_ON a WARN_ON_ONCE so it's not retriggerable]
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/powerpc/platforms/pseries/pseries_energy.c | 27 ++++++++++++++++--------
    1 file changed, 18 insertions(+), 9 deletions(-)

    --- a/arch/powerpc/platforms/pseries/pseries_energy.c
    +++ b/arch/powerpc/platforms/pseries/pseries_energy.c
    @@ -77,18 +77,27 @@ static u32 cpu_to_drc_index(int cpu)

    ret = drc.drc_index_start + (thread_index * drc.sequential_inc);
    } else {
    - const __be32 *indexes;
    -
    - indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
    - if (indexes == NULL)
    - goto err_of_node_put;
    + u32 nr_drc_indexes, thread_drc_index;

    /*
    - * The first element indexes[0] is the number of drc_indexes
    - * returned in the list. Hence thread_index+1 will get the
    - * drc_index corresponding to core number thread_index.
    + * The first element of ibm,drc-indexes array is the
    + * number of drc_indexes returned in the list. Hence
    + * thread_index+1 will get the drc_index corresponding
    + * to core number thread_index.
    */
    - ret = indexes[thread_index + 1];
    + rc = of_property_read_u32_index(dn, "ibm,drc-indexes",
    + 0, &nr_drc_indexes);
    + if (rc)
    + goto err_of_node_put;
    +
    + WARN_ON_ONCE(thread_index > nr_drc_indexes);
    + rc = of_property_read_u32_index(dn, "ibm,drc-indexes",
    + thread_index + 1,
    + &thread_drc_index);
    + if (rc)
    + goto err_of_node_put;
    +
    + ret = thread_drc_index;
    }

    rc = 0;

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