Commit d7c00bbb authored Mar 08, 2019 by Gautham R. Shenoy Committed by Greg Kroah-Hartman Apr 03, 2019

powerpc/pseries/energy: Use OF accessor functions to read ibm,drc-indexes



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: e83636ac ("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>

parent 0603e3a9

arch/powerpc/platforms/pseries/pseries_energy.c

+18 −9

Original line number	Diff line number	Diff line
		@@ -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;