@@ -480,6 +480,10 @@ has_cortex_a76_erratum_1463225(const struct arm64_cpu_capabilities *entry,
.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, \
CAP_MIDR_RANGE_LIST(midr_list)
+/* Track overall mitigation state. We are only mitigated if all cores are ok */
+static bool __hardenbp_enab = true;
+static bool __spectrev2_safe = true;
+
/*
* Generic helper for handling capabilties with multiple (match,enable) pairs
* of call backs, sharing the same capability bit.
@@ -522,6 +526,10 @@ static const struct midr_range spectre_v2_safe_list[] = {
{ /* sentinel */ }
};
+/*
+ * Track overall bp hardening for all heterogeneous cores in the machine.
+ * We are only considered "safe" if all booted cores are known safe.
+ */
static bool __maybe_unused
check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope)
{
@@ -543,6 +551,8 @@ check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope)
if (!need_wa)
return false;
+ __spectrev2_safe = false;
+
if (!IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR)) {
pr_warn_once("spectrev2 mitigation disabled by kernel configuration\n");
__hardenbp_enab = false;
@@ -552,11 +562,14 @@ check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope)
/* forced off */
if (__nospectre_v2) {
pr_info_once("spectrev2 mitigation disabled by command line option\n");
+ __hardenbp_enab = false;
return false;
}
- if (need_wa < 0)
+ if (need_wa < 0) {
pr_warn_once("ARM_SMCCC_ARCH_WORKAROUND_1 missing from firmware\n");
+ __hardenbp_enab = false;
+ }
return (need_wa > 0);
}
@@ -753,3 +766,15 @@ ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr,
{
return sprintf(buf, "Mitigation: __user pointer sanitization\n");
}
+
+ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ if (__spectrev2_safe)
+ return sprintf(buf, "Not affected\n");
+
+ if (__hardenbp_enab)
+ return sprintf(buf, "Mitigation: Branch predictor hardening\n");
+
+ return sprintf(buf, "Vulnerable\n");
+}