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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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