Merge pull request #1688 from JoelHutton/jh/variant_1_mitigations

Initial Spectre V1 mitigations (CVE-2017-5753).

include/lib/utils_def.h

@@ -162,4 +162,11 @@
 
 #define COMPILER_BARRIER() __asm__ volatile ("" ::: "memory")
 
+/* Compiler builtin of GCC >= 9 and planned in llvm */
+#ifdef __HAVE_SPECULATION_SAFE_VALUE
+# define SPECULATION_SAFE_VALUE(var) __builtin_speculation_safe_value(var)
+#else
+# define SPECULATION_SAFE_VALUE(var) var
+#endif
+
 #endif /* UTILS_DEF_H */

lib/psci/psci_stat.c

@@ -206,9 +206,9 @@ static int psci_get_stat(u_register_t target_cpu, unsigned int power_state,
 
 	if (pwrlvl > PSCI_CPU_PWR_LVL) {
 		/* Get the power domain index */
-		parent_idx = psci_cpu_pd_nodes[target_idx].parent_node;
+		parent_idx = SPECULATION_SAFE_VALUE(psci_cpu_pd_nodes[target_idx].parent_node);
 		for (lvl = PSCI_CPU_PWR_LVL + 1U; lvl < pwrlvl; lvl++)
-			parent_idx = psci_non_cpu_pd_nodes[parent_idx].parent_node;
+			parent_idx = SPECULATION_SAFE_VALUE(psci_non_cpu_pd_nodes[parent_idx].parent_node);
 
 		/* Get the non cpu power domain stats */
 		*psci_stat = psci_non_cpu_stat[parent_idx][stat_idx];