efi_loader: Add a test app

Add a simple app to use for testing. This is intended to do whatever it
needs to for testing purposes. For now it just prints a message and
exits boot services.

There was a considerable amount of discussion about whether it is OK to
call exit-boot-services and then return to U-Boot. This is not normally
done in a real application, since exit-boot-services is used to
completely disconnect from U-Boot. For now, this part is skipped.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

3 files changed, 67 insertions, 0 deletions

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 066f0ca0da7..58d49789f12 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -567,6 +567,16 @@ config BOOTEFI_HELLO_COMPILE
 	  No additional space will be required in the resulting U-Boot binary
 	  when this option is enabled.
 
+config BOOTEFI_TESTAPP_COMPILE
+	bool "Compile an EFI test app for testing"
+	default y
+	help
+	  This compiles an app designed for testing. It is packed into an image
+	  by the test.py testing frame in the setup_efi_image() function.
+
+	  No additional space will be required in the resulting U-Boot binary
+	  when this option is enabled.
+
 endif
 
 source "lib/efi/Kconfig"
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index 00d18966f9e..87131ab911d 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -20,6 +20,7 @@ apps-$(CONFIG_EFI_LOAD_FILE2_INITRD) += initrddump
 ifeq ($(CONFIG_GENERATE_ACPI_TABLE),)
 apps-y += dtbdump
 endif
+apps-$(CONFIG_BOOTEFI_TESTAPP_COMPILE) += testapp
 
 obj-$(CONFIG_CMD_BOOTEFI_HELLO) += helloworld_efi.o
 obj-$(CONFIG_EFI_BOOTMGR) += efi_bootmgr.o
diff --git a/lib/efi_loader/testapp.c b/lib/efi_loader/testapp.c
new file mode 100644
index 00000000000..804ca7e4679
--- /dev/null
+++ b/lib/efi_loader/testapp.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * EFI test application
+ *
+ * Copyright 2024 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * This test program is used to test the invocation of an EFI application.
+ * It writes a few messages to the console and then exits boot services
+ */
+
+#include <efi_api.h>
+
+static const efi_guid_t loaded_image_guid = EFI_LOADED_IMAGE_PROTOCOL_GUID;
+
+static struct efi_system_table *systable;
+static struct efi_boot_services *boottime;
+static struct efi_simple_text_output_protocol *con_out;
+
+/**
+ * efi_main() - entry point of the EFI application.
+ *
+ * @handle:	handle of the loaded image
+ * @systab:	system table
+ * Return:	status code
+ */
+efi_status_t EFIAPI efi_main(efi_handle_t handle,
+			     struct efi_system_table *systab)
+{
+	struct efi_loaded_image *loaded_image;
+	efi_status_t ret;
+
+	systable = systab;
+	boottime = systable->boottime;
+	con_out = systable->con_out;
+
+	/* Get the loaded image protocol */
+	ret = boottime->open_protocol(handle, &loaded_image_guid,
+				      (void **)&loaded_image, NULL, NULL,
+				      EFI_OPEN_PROTOCOL_GET_PROTOCOL);
+	if (ret != EFI_SUCCESS) {
+		con_out->output_string
+			(con_out, u"Cannot open loaded image protocol\r\n");
+		goto out;
+	}
+
+	/* UEFI requires CR LF */
+	con_out->output_string(con_out, u"U-Boot test app for EFI_LOADER\r\n");
+
+out:
+	con_out->output_string(con_out, u"Exiting test app\n");
+	ret = boottime->exit(handle, ret, 0, NULL);
+
+	/* We should never arrive here */
+	return ret;
+}