[U-Boot] [PATCH 08/14] efi_loader: Add "bootefi" command

[Alexander Graf]

In order to execute an EFI application, we need to bridge the gap between
U-Boot's notion of executing images and EFI's notion of doing the same.

The best path forward IMHO here is to stick completely to the way U-Boot
deals with payloads. You manually load them using whatever method to RAM
and then have a simple boot command to execute them. So in our case, you
would do

  # load mmc 0:1 $loadaddr grub.efi
  # bootefi $loadaddr

which then gets you into a grub shell. Fdt information known to U-boot
via the fdt addr command is also passed to the EFI payload.

Signed-off-by: Alexander Graf <agraf at suse.de>

---

v1 -> v2:

  - Move to GPLv2+
---
 common/Makefile      |   1 +
 common/cmd_bootefi.c | 154 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 155 insertions(+)
 create mode 100644 common/cmd_bootefi.c

diff --git a/common/Makefile b/common/Makefile
index 2a1d9f8..a7a728a 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -67,6 +67,7 @@ obj-$(CONFIG_CMD_SOURCE) += cmd_source.o
 obj-$(CONFIG_CMD_BDI) += cmd_bdinfo.o
 obj-$(CONFIG_CMD_BEDBUG) += bedbug.o cmd_bedbug.o
 obj-$(CONFIG_CMD_BMP) += cmd_bmp.o
+obj-$(CONFIG_EFI_LOADER) += cmd_bootefi.o
 obj-$(CONFIG_CMD_BOOTMENU) += cmd_bootmenu.o
 obj-$(CONFIG_CMD_BOOTLDR) += cmd_bootldr.o
 obj-$(CONFIG_CMD_BOOTSTAGE) += cmd_bootstage.o
diff --git a/common/cmd_bootefi.c b/common/cmd_bootefi.c
new file mode 100644
index 0000000..fde1942
--- /dev/null
+++ b/common/cmd_bootefi.c
@@ -0,0 +1,154 @@
+/*
+ *  EFI application loader
+ *
+ *  Copyright (c) 2016 Alexander Graf
+ *
+ *  SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <efi_loader.h>
+#include <libfdt_env.h>
+
+/* This list contains all the EFI objects our payload has access to */
+LIST_HEAD(efi_obj_list);
+
+/*
+ * When booting using the "bootefi" command, we don't know which
+ * physical device the file came from. So we create a pseudo-device
+ * called "bootefi" with the device path /bootefi.
+ *
+ * In addition to the originating device we also declare the file path
+ * of "bootefi" based loads to be /bootefi.
+ */
+static struct efi_device_path_file_path bootefi_dummy_path[] = {
+	{
+		.dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE,
+		.dp.sub_type = DEVICE_PATH_SUB_TYPE_FILE_PATH,
+		.dp.length = sizeof(bootefi_dummy_path[0]),
+		.str = { 'b','o','o','t','e','f','i' },
+	}, {
+		.dp.type = DEVICE_PATH_TYPE_END,
+		.dp.sub_type = DEVICE_PATH_SUB_TYPE_END,
+		.dp.length = sizeof(bootefi_dummy_path[0]),
+	}
+};
+
+static efi_status_t bootefi_open_dp(void *handle, efi_guid_t *protocol,
+			void **protocol_interface, void *agent_handle,
+			void *controller_handle, uint32_t attributes)
+{
+	*protocol_interface = bootefi_dummy_path;
+	return EFI_SUCCESS;
+}
+
+/* The EFI loaded_image interface for the image executed via "bootefi" */
+static struct efi_loaded_image loaded_image_info = {
+	.device_handle = bootefi_dummy_path,
+	.file_path = bootefi_dummy_path,
+};
+
+/* The EFI object struct for the image executed via "bootefi" */
+static struct efi_object loaded_image_info_obj = {
+	.handle = &loaded_image_info,
+	.protocols = {
+		{
+			/* When asking for the loaded_image interface, just
+			 * return handle which points to loaded_image_info */
+			.guid = &efi_guid_loaded_image,
+			.open = &efi_return_handle,
+		},
+		{
+			/* When asking for the device path interface, return
+			 * bootefi_dummy_path */
+			.guid = &efi_guid_device_path,
+			.open = &bootefi_open_dp,
+		},
+	},
+};
+
+/* The EFI object struct for the device the "bootefi" image was loaded from */
+static struct efi_object bootefi_device_obj = {
+	.handle = bootefi_dummy_path,
+	.protocols = {
+		{
+			/* When asking for the device path interface, return
+			 * bootefi_dummy_path */
+			.guid = &efi_guid_device_path,
+			.open = &bootefi_open_dp,
+		}
+	},
+};
+
+/*
+ * Load an EFI payload into a newly allocated piece of memory, register all
+ * EFI objects it would want to access and jump to it.
+ */
+static unsigned long do_bootefi_exec(void *efi)
+{
+	ulong (*entry)(void *image_handle, struct efi_system_table *st);
+
+	/*
+	 * gd lives in a fixed register which may get clobbered while we execute
+	 * the payload. So save it here and restore it on every callback entry
+	 */
+	efi_save_gd();
+
+	/* Update system table to point to our currently loaded FDT */
+	systab.tables[0].table = working_fdt;
+
+	if (!working_fdt) {
+		printf("WARNING: No device tree loaded, expect boot to fail\n");
+		systab.nr_tables = 0;
+	}
+
+	/* Load the EFI payload */
+	entry = efi_load_pe(efi, &loaded_image_info);
+	if (!entry)
+		return -1;
+
+	/* Initialize and populate EFI object list */
+	INIT_LIST_HEAD(&efi_obj_list);
+	list_add_tail(&loaded_image_info_obj.link, &efi_obj_list);
+	list_add_tail(&bootefi_device_obj.link, &efi_obj_list);
+#ifdef CONFIG_PARTITIONS
+	efi_disk_register();
+#endif
+
+	/* Call our payload! */
+#ifdef DEBUG_EFI
+	printf("%s:%d Jumping to 0x%lx\n", __func__, __LINE__, (long)entry);
+#endif
+	return entry(&loaded_image_info, &systab);
+}
+
+
+/* Interpreter command to boot an arbitrary EFI image from memory */
+static int do_bootefi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	char *saddr;
+	unsigned long addr;
+	int r = 0;
+
+	if (argc < 2)
+		return 1;
+	saddr = argv[1];
+
+	addr = simple_strtoul(saddr, NULL, 16);
+
+	printf("## Starting EFI application at 0x%08lx ...\n", addr);
+	r = do_bootefi_exec((void *)addr);
+	printf("## Application terminated, r = %d\n", r);
+
+	if (r != 0)
+		r = 1;
+
+	return r;
+}
+
+U_BOOT_CMD(
+	bootefi, 2, 0, do_bootefi,
+	"Boot from an EFI image in memory",
+	"<image address>\n"
+);
-- 
2.1.4