efi_loader: add bootmgr

Similar to a "real" UEFI implementation, the bootmgr looks at the
BootOrder and BootXXXX variables to try to find an EFI payload to load
and boot.  This is added as a sub-command of bootefi.

The idea is that the distro bootcmd would first try loading a payload
via the bootmgr, and then if that fails (ie. first boot or corrupted
EFI variables) it would fallback to loading bootaa64.efi.  (Which
would then load fallback.efi which would look for \EFI\*\boot.csv and
populate BootOrder and BootXXXX based on what it found.)

Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

4 files changed, 185 insertions, 4 deletions

diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index 301bf7b507..ddb978f650 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -17,7 +17,7 @@ endif
 obj-$(CONFIG_CMD_BOOTEFI_HELLO) += helloworld_efi.o
 obj-y += efi_image_loader.o efi_boottime.o efi_runtime.o efi_console.o
 obj-y += efi_memory.o efi_device_path_to_text.o efi_device_path.o
-obj-y += efi_file.o efi_variable.o
+obj-y += efi_file.o efi_variable.o efi_bootmgr.o
 obj-$(CONFIG_LCD) += efi_gop.o
 obj-$(CONFIG_DM_VIDEO) += efi_gop.o
 obj-$(CONFIG_PARTITIONS) += efi_disk.o
diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
new file mode 100644
index 0000000000..857d88a879
--- /dev/null
+++ b/lib/efi_loader/efi_bootmgr.c
@@ -0,0 +1,180 @@
+/*
+ *  EFI utils
+ *
+ *  Copyright (c) 2017 Rob Clark
+ *
+ *  SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <charset.h>
+#include <malloc.h>
+#include <efi_loader.h>
+
+static const struct efi_boot_services *bs;
+static const struct efi_runtime_services *rs;
+
+#define LOAD_OPTION_ACTIVE		0x00000001
+#define LOAD_OPTION_FORCE_RECONNECT	0x00000002
+#define LOAD_OPTION_HIDDEN		0x00000008
+
+/*
+ * bootmgr implements the logic of trying to find a payload to boot
+ * based on the BootOrder + BootXXXX variables, and then loading it.
+ *
+ * TODO detecting a special key held (f9?) and displaying a boot menu
+ * like you would get on a PC would be clever.
+ *
+ * TODO if we had a way to write and persist variables after the OS
+ * has started, we'd also want to check OsIndications to see if we
+ * should do normal or recovery boot.
+ */
+
+
+/*
+ * See section 3.1.3 in the v2.7 UEFI spec for more details on
+ * the layout of EFI_LOAD_OPTION.  In short it is:
+ *
+ *    typedef struct _EFI_LOAD_OPTION {
+ *        UINT32 Attributes;
+ *        UINT16 FilePathListLength;
+ *        // CHAR16 Description[];   <-- variable length, NULL terminated
+ *        // EFI_DEVICE_PATH_PROTOCOL FilePathList[];  <-- FilePathListLength bytes
+ *        // UINT8 OptionalData[];
+ *    } EFI_LOAD_OPTION;
+ */
+struct load_option {
+	u32 attributes;
+	u16 file_path_length;
+	u16 *label;
+	struct efi_device_path *file_path;
+	u8 *optional_data;
+};
+
+/* parse an EFI_LOAD_OPTION, as described above */
+static void parse_load_option(struct load_option *lo, void *ptr)
+{
+	lo->attributes = *(u32 *)ptr;
+	ptr += sizeof(u32);
+
+	lo->file_path_length = *(u16 *)ptr;
+	ptr += sizeof(u16);
+
+	lo->label = ptr;
+	ptr += (utf16_strlen(lo->label) + 1) * 2;
+
+	lo->file_path = ptr;
+	ptr += lo->file_path_length;
+
+	lo->optional_data = ptr;
+}
+
+/* free() the result */
+static void *get_var(u16 *name, const efi_guid_t *vendor,
+		     unsigned long *size)
+{
+	efi_guid_t *v = (efi_guid_t *)vendor;
+	efi_status_t ret;
+	void *buf = NULL;
+
+	*size = 0;
+	EFI_CALL(ret = rs->get_variable((s16 *)name, v, NULL, size, buf));
+	if (ret == EFI_BUFFER_TOO_SMALL) {
+		buf = malloc(*size);
+		EFI_CALL(ret = rs->get_variable((s16 *)name, v, NULL, size, buf));
+	}
+
+	if (ret != EFI_SUCCESS) {
+		free(buf);
+		*size = 0;
+		return NULL;
+	}
+
+	return buf;
+}
+
+/*
+ * Attempt to load load-option number 'n', returning device_path and file_path
+ * if successful.  This checks that the EFI_LOAD_OPTION is active (enabled)
+ * and that the specified file to boot exists.
+ */
+static void *try_load_entry(uint16_t n, struct efi_device_path **device_path,
+			    struct efi_device_path **file_path)
+{
+	struct load_option lo;
+	u16 varname[] = L"Boot0000";
+	u16 hexmap[] = L"0123456789ABCDEF";
+	void *load_option, *image = NULL;
+	unsigned long size;
+
+	varname[4] = hexmap[(n & 0xf000) >> 12];
+	varname[5] = hexmap[(n & 0x0f00) >> 8];
+	varname[6] = hexmap[(n & 0x00f0) >> 4];
+	varname[7] = hexmap[(n & 0x000f) >> 0];
+
+	load_option = get_var(varname, &efi_global_variable_guid, &size);
+	if (!load_option)
+		return NULL;
+
+	parse_load_option(&lo, load_option);
+
+	if (lo.attributes & LOAD_OPTION_ACTIVE) {
+		efi_status_t ret;
+		u16 *str = NULL;
+
+		debug("%s: trying to load \"%ls\" from: %ls\n", __func__,
+		      lo.label, (str = efi_dp_str(lo.file_path)));
+		efi_free_pool(str);
+
+		ret = efi_load_image_from_path(lo.file_path, &image);
+
+		if (ret != EFI_SUCCESS)
+			goto error;
+
+		printf("Booting: %ls\n", lo.label);
+		efi_dp_split_file_path(lo.file_path, device_path, file_path);
+	}
+
+error:
+	free(load_option);
+
+	return image;
+}
+
+/*
+ * Attempt to load, in the order specified by BootOrder EFI variable, the
+ * available load-options, finding and returning the first one that can
+ * be loaded successfully.
+ */
+void *efi_bootmgr_load(struct efi_device_path **device_path,
+		       struct efi_device_path **file_path)
+{
+	uint16_t *bootorder;
+	unsigned long size;
+	void *image = NULL;
+	int i, num;
+
+	__efi_entry_check();
+
+	bs = systab.boottime;
+	rs = systab.runtime;
+
+	bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
+	if (!bootorder)
+		goto error;
+
+	num = size / sizeof(uint16_t);
+	for (i = 0; i < num; i++) {
+		debug("%s: trying to load Boot%04X\n", __func__, bootorder[i]);
+		image = try_load_entry(bootorder[i], device_path, file_path);
+		if (image)
+			break;
+	}
+
+	free(bootorder);
+
+error:
+	__efi_exit_check();
+
+	return image;
+}
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 90f0051484..f97b0ca4ab 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -814,8 +814,8 @@ void efi_setup_loaded_image(struct efi_loaded_image *info, struct efi_object *ob
 	list_add_tail(&obj->link, &efi_obj_list);
 }
 
-static efi_status_t load_image_from_path(struct efi_device_path *file_path,
-					 void **buffer)
+efi_status_t efi_load_image_from_path(struct efi_device_path *file_path,
+				      void **buffer)
 {
 	struct efi_file_info *info = NULL;
 	struct efi_file_handle *f;
@@ -875,7 +875,7 @@ static efi_status_t EFIAPI efi_load_image(bool boot_policy,
 		struct efi_device_path *dp, *fp;
 		efi_status_t ret;
 
-		ret = load_image_from_path(file_path, &source_buffer);
+		ret = efi_load_image_from_path(file_path, &source_buffer);
 		if (ret != EFI_SUCCESS) {
 			free(info);
 			free(obj);
diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c
index 469acae082..242e6a504b 100644
--- a/lib/efi_loader/efi_image_loader.c
+++ b/lib/efi_loader/efi_image_loader.c
@@ -15,6 +15,7 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+const efi_guid_t efi_global_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
 const efi_guid_t efi_guid_device_path = DEVICE_PATH_GUID;
 const efi_guid_t efi_guid_loaded_image = LOADED_IMAGE_GUID;
 const efi_guid_t efi_simple_file_system_protocol_guid =