1 files changed, 27 insertions, 0 deletions
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index c5685179db5a..72f432d23ec5 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -143,3 +143,30 @@ asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f)
 	pr_err_ratelimited(FW_BUG "register x18 corrupted by EFI %s\n", f);
 	return s;
 }
+
+DEFINE_SPINLOCK(efi_rt_lock);
+
+asmlinkage u64 *efi_rt_stack_top __ro_after_init;
+
+/* EFI requires 8 KiB of stack space for runtime services */
+static_assert(THREAD_SIZE >= SZ_8K);
+
+static int __init arm64_efi_rt_init(void)
+{
+	void *p;
+
+	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+		return 0;
+
+	p = __vmalloc_node(THREAD_SIZE, THREAD_ALIGN, GFP_KERNEL,
+			   NUMA_NO_NODE, &&l);
+l:	if (!p) {
+		pr_warn("Failed to allocate EFI runtime stack\n");
+		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+		return -ENOMEM;
+	}
+
+	efi_rt_stack_top = p + THREAD_SIZE;
+	return 0;
+}
+core_initcall(arm64_efi_rt_init);