Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64...

[sfrench/cifs-2.6.git] / drivers / perf / arm-cmn.c

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index 564da632b8d1928451b9c950e3b3a6d5b5d45720..7ef9c7e4836b72498db6cd8d5263c2ea5bf9f730 100644 (file)
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -2306,6 +2306,17 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
                                dev_dbg(cmn->dev, "ignoring external node %llx\n", reg);
                                continue;
                        }
+                       /*
+                        * AmpereOneX erratum AC04_MESH_1 makes some XPs report a bogus
+                        * child count larger than the number of valid child pointers.
+                        * A child offset of 0 can only occur on CMN-600; otherwise it
+                        * would imply the root node being its own grandchild, which
+                        * we can safely dismiss in general.
+                        */
+                       if (reg == 0 && cmn->part != PART_CMN600) {
+                               dev_dbg(cmn->dev, "bogus child pointer?\n");
+                               continue;
+                       }
 
                        arm_cmn_init_node_info(cmn, reg & CMN_CHILD_NODE_ADDR, dn);