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@@ -0,0 +1,180 @@
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+/*
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+ * EFI utils
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+ *
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+ * Copyright (c) 2017 Rob Clark
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+ *
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+ * SPDX-License-Identifier: GPL-2.0+
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+ */
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+
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+#include <common.h>
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+#include <charset.h>
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+#include <malloc.h>
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+#include <efi_loader.h>
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+
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+static const struct efi_boot_services *bs;
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+static const struct efi_runtime_services *rs;
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+
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+#define LOAD_OPTION_ACTIVE 0x00000001
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+#define LOAD_OPTION_FORCE_RECONNECT 0x00000002
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+#define LOAD_OPTION_HIDDEN 0x00000008
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+
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+/*
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+ * bootmgr implements the logic of trying to find a payload to boot
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+ * based on the BootOrder + BootXXXX variables, and then loading it.
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+ *
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+ * TODO detecting a special key held (f9?) and displaying a boot menu
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+ * like you would get on a PC would be clever.
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+ *
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+ * TODO if we had a way to write and persist variables after the OS
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+ * has started, we'd also want to check OsIndications to see if we
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+ * should do normal or recovery boot.
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+ */
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+
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+
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+/*
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+ * See section 3.1.3 in the v2.7 UEFI spec for more details on
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+ * the layout of EFI_LOAD_OPTION. In short it is:
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+ *
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+ * typedef struct _EFI_LOAD_OPTION {
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+ * UINT32 Attributes;
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+ * UINT16 FilePathListLength;
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+ * // CHAR16 Description[]; <-- variable length, NULL terminated
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+ * // EFI_DEVICE_PATH_PROTOCOL FilePathList[]; <-- FilePathListLength bytes
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+ * // UINT8 OptionalData[];
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+ * } EFI_LOAD_OPTION;
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+ */
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+struct load_option {
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+ u32 attributes;
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+ u16 file_path_length;
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+ u16 *label;
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+ struct efi_device_path *file_path;
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+ u8 *optional_data;
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+};
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+
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+/* parse an EFI_LOAD_OPTION, as described above */
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+static void parse_load_option(struct load_option *lo, void *ptr)
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+{
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+ lo->attributes = *(u32 *)ptr;
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+ ptr += sizeof(u32);
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+
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+ lo->file_path_length = *(u16 *)ptr;
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+ ptr += sizeof(u16);
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+
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+ lo->label = ptr;
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+ ptr += (utf16_strlen(lo->label) + 1) * 2;
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+
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+ lo->file_path = ptr;
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+ ptr += lo->file_path_length;
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+
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+ lo->optional_data = ptr;
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+}
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+
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+/* free() the result */
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+static void *get_var(u16 *name, const efi_guid_t *vendor,
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+ unsigned long *size)
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+{
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+ efi_guid_t *v = (efi_guid_t *)vendor;
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+ efi_status_t ret;
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+ void *buf = NULL;
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+
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+ *size = 0;
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+ EFI_CALL(ret = rs->get_variable((s16 *)name, v, NULL, size, buf));
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+ if (ret == EFI_BUFFER_TOO_SMALL) {
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+ buf = malloc(*size);
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+ EFI_CALL(ret = rs->get_variable((s16 *)name, v, NULL, size, buf));
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+ }
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+
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+ if (ret != EFI_SUCCESS) {
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+ free(buf);
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+ *size = 0;
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+ return NULL;
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+ }
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+
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+ return buf;
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+}
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+
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+/*
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+ * Attempt to load load-option number 'n', returning device_path and file_path
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+ * if successful. This checks that the EFI_LOAD_OPTION is active (enabled)
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+ * and that the specified file to boot exists.
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+ */
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+static void *try_load_entry(uint16_t n, struct efi_device_path **device_path,
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+ struct efi_device_path **file_path)
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+{
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+ struct load_option lo;
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+ u16 varname[] = L"Boot0000";
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+ u16 hexmap[] = L"0123456789ABCDEF";
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+ void *load_option, *image = NULL;
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+ unsigned long size;
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+
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+ varname[4] = hexmap[(n & 0xf000) >> 12];
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+ varname[5] = hexmap[(n & 0x0f00) >> 8];
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+ varname[6] = hexmap[(n & 0x00f0) >> 4];
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+ varname[7] = hexmap[(n & 0x000f) >> 0];
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+
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+ load_option = get_var(varname, &efi_global_variable_guid, &size);
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+ if (!load_option)
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+ return NULL;
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+
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+ parse_load_option(&lo, load_option);
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+
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+ if (lo.attributes & LOAD_OPTION_ACTIVE) {
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+ efi_status_t ret;
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+ u16 *str = NULL;
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+
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+ debug("%s: trying to load \"%ls\" from: %ls\n", __func__,
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+ lo.label, (str = efi_dp_str(lo.file_path)));
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+ efi_free_pool(str);
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+
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+ ret = efi_load_image_from_path(lo.file_path, &image);
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+
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+ if (ret != EFI_SUCCESS)
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+ goto error;
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+
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+ printf("Booting: %ls\n", lo.label);
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+ efi_dp_split_file_path(lo.file_path, device_path, file_path);
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+ }
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+
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+error:
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+ free(load_option);
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+
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+ return image;
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+}
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+
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+/*
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+ * Attempt to load, in the order specified by BootOrder EFI variable, the
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+ * available load-options, finding and returning the first one that can
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+ * be loaded successfully.
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+ */
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+void *efi_bootmgr_load(struct efi_device_path **device_path,
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+ struct efi_device_path **file_path)
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+{
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+ uint16_t *bootorder;
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+ unsigned long size;
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+ void *image = NULL;
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+ int i, num;
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+
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+ __efi_entry_check();
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+
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+ bs = systab.boottime;
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+ rs = systab.runtime;
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+
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+ bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
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+ if (!bootorder)
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+ goto error;
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+
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+ num = size / sizeof(uint16_t);
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+ for (i = 0; i < num; i++) {
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+ debug("%s: trying to load Boot%04X\n", __func__, bootorder[i]);
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+ image = try_load_entry(bootorder[i], device_path, file_path);
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+ if (image)
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+ break;
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+ }
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+
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+ free(bootorder);
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+
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+error:
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+ __efi_exit_check();
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+
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+ return image;
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+}
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