1 files changed, 180 insertions, 0 deletions
diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
new file mode 100644
index 00000000000..857d88a879e
--- /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;
+}