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 <robdcl...@gmail.com>
---
 cmd/bootefi.c                     |  48 ++++++++++-
 include/config_distro_bootcmd.h   |   5 ++
 include/efi_api.h                 |   4 +
 include/efi_loader.h              |   6 ++
 lib/efi_loader/Makefile           |   2 +-
 lib/efi_loader/efi_bootmgr.c      | 169 ++++++++++++++++++++++++++++++++++++++
 lib/efi_loader/efi_boottime.c     |   6 +-
 lib/efi_loader/efi_image_loader.c |   1 +
 8 files changed, 235 insertions(+), 6 deletions(-)
 create mode 100644 lib/efi_loader/efi_bootmgr.c

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index 80f52e9e35..02a0dd159b 100644
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -219,6 +219,36 @@ exit:
        return ret;
 }
 
+static int do_bootefi_bootmgr_exec(unsigned long fdt_addr)
+{
+       struct efi_device_path *device_path, *file_path;
+       void *addr;
+       efi_status_t r;
+
+       /* Initialize and populate EFI object list */
+       if (!efi_obj_list_initalized)
+               efi_init_obj_list();
+
+       /*
+        * 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();
+
+       addr = efi_bootmgr_load(&device_path, &file_path);
+       if (!addr)
+               return 1;
+
+       printf("## Starting EFI application at %p ...\n", addr);
+       r = do_bootefi_exec(addr, (void*)fdt_addr, device_path, file_path);
+       printf("## Application terminated, r = %lu\n",
+              r & ~EFI_ERROR_MASK);
+
+       if (r != EFI_SUCCESS)
+               return 1;
+
+       return 0;
+}
 
 /* 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[])
@@ -237,7 +267,14 @@ static int do_bootefi(cmd_tbl_t *cmdtp, int flag, int 
argc, char * const argv[])
                memcpy((char *)addr, __efi_hello_world_begin, size);
        } else
 #endif
-       {
+       if (!strcmp(argv[1], "bootmgr")) {
+               unsigned long fdt_addr = 0;
+
+               if (argc > 2)
+                       fdt_addr = simple_strtoul(argv[2], NULL, 16);
+
+               return do_bootefi_bootmgr_exec(fdt_addr);
+       } else {
                saddr = argv[1];
 
                addr = simple_strtoul(saddr, NULL, 16);
@@ -270,7 +307,11 @@ static char bootefi_help_text[] =
        "hello\n"
        "  - boot a sample Hello World application stored within U-Boot"
 #endif
-       ;
+       "bootmgr [fdt addr]\n"
+       "  - load and boot EFI payload based on BootOrder/BootXXXX variables.\n"
+       "\n"
+       "    If specified, the device tree located at <fdt address> gets\n"
+       "    exposed as EFI configuration table.\n";
 #endif
 
 U_BOOT_CMD(
@@ -308,6 +349,9 @@ void efi_set_bootdev(const char *dev, const char *devnr, 
const char *path)
 #endif
        }
 
+       if (!path)
+               return;
+
        if (strcmp(dev, "Net")) {
                /* Add leading / to fs paths, because they're absolute */
                snprintf(filename, sizeof(filename), "/%s", path);
diff --git a/include/config_distro_bootcmd.h b/include/config_distro_bootcmd.h
index d8dab8e46a..94ccab02d2 100644
--- a/include/config_distro_bootcmd.h
+++ b/include/config_distro_bootcmd.h
@@ -112,6 +112,11 @@
 
 #define BOOTENV_SHARED_EFI                                                \
        "boot_efi_binary="                                                \
+               "if fdt addr ${fdt_addr_r}; then "                        \
+                       "bootefi bootmgr ${fdt_addr_r};"                  \
+               "else "                                                   \
+                       "bootefi bootmgr ${fdtcontroladdr};"              \
+               "fi;"                                                     \
                "load ${devtype} ${devnum}:${distro_bootpart} "           \
                        "${kernel_addr_r} efi/boot/"BOOTEFI_NAME"; "      \
                "if fdt addr ${fdt_addr_r}; then "                        \
diff --git a/include/efi_api.h b/include/efi_api.h
index 1aae96355f..d0aefa8221 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -211,6 +211,10 @@ struct efi_runtime_services {
        EFI_GUID(0x00000000, 0x0000, 0x0000, 0x00, 0x00, \
                 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
 
+#define EFI_GLOBAL_VARIABLE_GUID \
+       EFI_GUID(0x8be4df61, 0x93ca, 0x11d2, 0xaa, 0x0d, \
+                0x00, 0xe0, 0x98, 0x03, 0x2b, 0x8c)
+
 #define LOADED_IMAGE_PROTOCOL_GUID \
        EFI_GUID(0x5b1b31a1, 0x9562, 0x11d2, 0x8e, 0x3f, \
                 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b)
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 9cb568e615..1f335dbac5 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -61,6 +61,7 @@ extern const struct efi_device_path_to_text_protocol 
efi_device_path_to_text;
 
 uint16_t *efi_dp_str(struct efi_device_path *dp);
 
+extern const efi_guid_t efi_global_variable_guid;
 extern const efi_guid_t efi_guid_console_control;
 extern const efi_guid_t efi_guid_device_path;
 extern const efi_guid_t efi_guid_loaded_image;
@@ -209,6 +210,8 @@ efi_status_t efi_install_configuration_table(const 
efi_guid_t *guid, void *table
 void efi_setup_loaded_image(struct efi_loaded_image *info, struct efi_object 
*obj,
                            struct efi_device_path *device_path,
                            struct efi_device_path *file_path);
+efi_status_t efi_load_image_from_path(struct efi_device_path *file_path,
+                                     void **buffer);
 
 #ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
 extern void *efi_bounce_buffer;
@@ -281,6 +284,9 @@ efi_status_t EFIAPI efi_set_variable(s16 *variable_name,
                efi_guid_t *vendor, u32 attributes,
                unsigned long data_size, void *data);
 
+void *efi_bootmgr_load(struct efi_device_path **device_path,
+                      struct efi_device_path **file_path);
+
 #else /* defined(EFI_LOADER) && !defined(CONFIG_SPL_BUILD) */
 
 /* Without CONFIG_EFI_LOADER we don't have a runtime section, stub it out */
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index f58cb13337..930c0e218e 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -16,7 +16,7 @@ always := $(efiprogs-y)
 obj-$(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..8246ddd48f
--- /dev/null
+++ b/lib/efi_loader/efi_bootmgr.c
@@ -0,0 +1,169 @@
+/*
+ *  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;
+};
+
+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;
+}
+
+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;
+}
+
+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 0bb64f0351..0dbbccb682 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -749,8 +749,8 @@ 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;
@@ -808,7 +808,7 @@ 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 =
-- 
2.13.0

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