@@ -59,9 +59,17 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
return ok;
}
+static inline bool __init __early_cpu_has_rndr(void)
+{
+ /* Open code as we run prior to the first call to cpufeature. */
+ unsigned long ftr = read_sysreg_s(SYS_ID_AA64ISAR0_EL1);
+ return (ftr >> ID_AA64ISAR0_RNDR_SHIFT) & 0xf;
+}
+
#else
static inline bool __arm64_rndr(unsigned long *v) { return false; }
+static inline bool __init __early_cpu_has_rndr(void) { return false; }
#endif /* CONFIG_ARCH_RANDOM */
#endif /* _ASM_ARCHRANDOM_H */
@@ -120,6 +120,17 @@ u64 __init kaslr_early_init(u64 dt_phys)
return 0;
}
+ /*
+ * Mix in any entropy obtainable architecturally, open coded
+ * since this runs extremely early.
+ */
+ if (__early_cpu_has_rndr()) {
+ unsigned long raw;
+
+ if (__arm64_rndr(&raw))
+ seed ^= raw;
+ }
+
if (!seed) {
kaslr_status = KASLR_DISABLED_NO_SEED;
return 0;