efi_selftest: check executing in EL2

UEFI binaries should be executed in EL2 or EL1 even if U-Boot is started
in EL3. Provide a unit test.

Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

diff --git a/lib/efi_selftest/Makefile b/lib/efi_selftest/Makefile
index 17fbfad..d78bf7d 100644 (file)
--- a/lib/efi_selftest/Makefile
+++ b/lib/efi_selftest/Makefile
@@ -51,6 +51,7 @@ efi_selftest_variables_runtime.o \
 efi_selftest_watchdog.o
 
 obj-$(CONFIG_EFI_ECPT) += efi_selftest_ecpt.o
+obj-$(CONFIG_ARM64) += efi_selftest_el.o
 obj-$(CONFIG_NETDEVICES) += efi_selftest_snp.o
 obj-$(CONFIG_EFI_HTTP_PROTOCOL) += efi_selftest_http.o
 obj-$(CONFIG_EFI_HTTP_PROTOCOL) += efi_selftest_ipconfig.o

diff --git a/lib/efi_selftest/efi_selftest_el.c b/lib/efi_selftest/efi_selftest_el.c
new file mode 100644 (file)
index 0000000..f9941ca
--- /dev/null
+++ b/lib/efi_selftest/efi_selftest_el.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Check current exception level on ARMv8.
+ */
+#include <efi_loader.h>
+#include <efi_selftest.h>
+
+/**
+ * current_exception_level()
+ *
+ * Return:     current exception level, 0 - 3
+ */
+static unsigned int current_exception_level(void)
+{
+       unsigned long el;
+
+       asm volatile (
+               "MRS %0, CurrentEL"
+               : "=r" (el) : : );
+
+       return (el >> 2) & 0x3;
+}
+
+/**
+ * execute() - execute test
+ *
+ * Check that the exception level is not EL3.
+ */
+static int execute(void)
+{
+       unsigned int el = current_exception_level();
+
+       efi_st_printf("Exception level EL%u\n", el);
+       if (el != 1 && el != 2) {
+               efi_st_error("EL1 or EL2 expected");
+               return EFI_ST_FAILURE;
+       }
+
+       return EFI_ST_SUCCESS;
+}
+
+EFI_UNIT_TEST(el) = {
+       .name = "exception level",
+       .phase = EFI_EXECUTE_BEFORE_BOOTTIME_EXIT,
+       .execute = execute,
+};