From ce9afe08e71e3f7d64f337a6e932e50849230fc2 Mon Sep 17 00:00:00 2001
From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Date: Fri, 8 Mar 2019 21:03:24 +0530
Subject: [PATCH] powerpc/pseries/energy: Use OF accessor functions to read
ibm,drc-indexes
References: bsc#1129080
Patch-mainline: v5.1-rc3
Git-commit: ce9afe08e71e3f7d64f337a6e932e50849230fc2
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>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
.../platforms/pseries/pseries_energy.c | 28 +++++++++++--------
1 file changed, 17 insertions(+), 11 deletions(-)
--- a/arch/powerpc/platforms/pseries/pseries_energy.c
+++ b/arch/powerpc/platforms/pseries/pseries_energy.c
@@ -38,27 +38,33 @@ static int sysfs_entries;
static u32 cpu_to_drc_index(int cpu)
{
struct device_node *dn = NULL;
- const int *indexes;
+ u32 nr_drc_indexes, i_drc_index;
int i;
- int rc = 1;
+ int rc;
u32 ret = 0;
dn = of_find_node_by_path("/cpus");
if (dn == NULL)
goto err;
- indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
- if (indexes == NULL)
- goto err_of_node_put;
+
/* Convert logical cpu number to core number */
i = cpu_core_index_of_thread(cpu);
+
/*
- * The first element indexes[0] is the number of drc_indexes
- * returned in the list. Hence i+1 will get the drc_index
- * corresponding to core number i.
+ * The first element of "ibm,drc-indexes" is the number of
+ * drc_indexes returned in the list. Hence i + 1 will get the
+ * drc_index corresponding to core number i.
*/
- WARN_ON(i > indexes[0]);
- ret = indexes[i + 1];
- rc = 0;
+ rc = of_property_read_u32_index(dn, "ibm,drc-indexes",
+ 0, &nr_drc_indexes);
+ if (rc)
+ goto err_of_node_put;
+
+ WARN_ON_ONCE(i > nr_drc_indexes);
+ rc = of_property_read_u32_index(dn, "ibm,drc-indexes",
+ i + 1, &i_drc_index);
+ if (!rc)
+ ret = i_drc_index;
err_of_node_put:
of_node_put(dn);
--
2.20.1