[PATCH v6 09/12] efi_loader: Add a test app

[Ilias Apalodimas]

Hi Simon,

On Fri, 27 Sept 2024 at 01:04, Simon Glass <sjg at chromium.org> wrote:
>
> 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.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> (no changes since v1)
>
>  lib/efi_loader/Kconfig   | 10 ++++++
>  lib/efi_loader/Makefile  |  1 +
>  lib/efi_loader/testapp.c | 68 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 79 insertions(+)
>  create mode 100644 lib/efi_loader/testapp.c
>
> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> index 6f6fa8d629d..41083e7c137 100644
> --- a/lib/efi_loader/Kconfig
> +++ b/lib/efi_loader/Kconfig
> @@ -564,6 +564,16 @@ 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..feb444c92e9
> --- /dev/null
> +++ b/lib/efi_loader/testapp.c
> @@ -0,0 +1,68 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Hello world EFI application
> + *
> + * Copyright 2024 Google LLC
> + * Written by Simon Glass <sjg at 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;
> +       efi_uintn_t map_size;
> +       efi_uintn_t map_key;
> +       efi_uintn_t desc_size;
> +       u32 desc_version;
> +
> +       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:
> +       map_size = 0;
> +       ret = boottime->get_memory_map(&map_size, NULL, &map_key, &desc_size,
> +                                      &desc_version);
> +       con_out->output_string(con_out, u"Exiting boot sevices\n");
> +
> +       /* exit boot services so that this part of U-Boot can be tested */
> +       boottime->exit_boot_services(handle, map_key);

What Heinrich keeps repeating here, is that after you call EBS, boot
services must not be called again.

> +
> +       /* now exit for real */
> +       ret = boottime->exit(handle, ret, 0, NULL);

IOW this is wrong. It might happen to work because not much has run
and the memory will still be there. But you certainly should not rely
on that

Thanks

/Ilias
> +
> +       /* We should never arrive here */
> +       return ret;
> +}
> --
> 2.43.0
>