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

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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: e83636ac33 ("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>
This commit is contained in:
Gautham R. Shenoy 2019-03-08 21:03:24 +05:30 committed by Michael Ellerman
parent d947075739
commit ce9afe08e7
1 changed files with 18 additions and 9 deletions
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27
arch/powerpc/platforms/pseries/pseries_energy.c
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@ -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;