@@ -495,6 +495,14 @@ static inline int arm64_get_ssbd_state(void)
void arm64_set_ssbd_mitigation(bool state);
+/* Watch out, ordering is important here. */
+enum mitigation_state {
+ SPECTRE_UNAFFECTED,
+ SPECTRE_MITIGATED,
+ SPECTRE_VULNERABLE,
+};
+
+enum mitigation_state arm64_get_spectre_bhb_state(void);
#endif /* __ASSEMBLY__ */
#endif
@@ -730,14 +730,39 @@ ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr,
return sprintf(buf, "Mitigation: __user pointer sanitization\n");
}
+static const char *get_bhb_affected_string(enum mitigation_state bhb_state)
+{
+ switch (bhb_state) {
+ case SPECTRE_UNAFFECTED:
+ return "";
+ default:
+ case SPECTRE_VULNERABLE:
+ return ", but not BHB";
+ case SPECTRE_MITIGATED:
+ return ", BHB";
+ }
+}
+
ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr,
char *buf)
{
- if (__spectrev2_safe)
- return sprintf(buf, "Not affected\n");
+ enum mitigation_state bhb_state = arm64_get_spectre_bhb_state();
+ const char *bhb_str = get_bhb_affected_string(bhb_state);
+ const char *v2_str = "Branch predictor hardening";
+
+ if (__spectrev2_safe) {
+ if (bhb_state == SPECTRE_UNAFFECTED)
+ return sprintf(buf, "Not affected\n");
+
+ /*
+ * Platforms affected by Spectre-BHB can't report
+ * "Not affected" for Spectre-v2.
+ */
+ v2_str = "CSV2";
+ }
if (__hardenbp_enab)
- return sprintf(buf, "Mitigation: Branch predictor hardening\n");
+ return sprintf(buf, "Mitigation: %s%s\n", v2_str, bhb_str);
return sprintf(buf, "Vulnerable\n");
}
@@ -758,3 +783,10 @@ ssize_t cpu_show_spec_store_bypass(struct device *dev,
return sprintf(buf, "Vulnerable\n");
}
+
+static enum mitigation_state spectre_bhb_state;
+
+enum mitigation_state arm64_get_spectre_bhb_state(void)
+{
+ return spectre_bhb_state;
+}