[RFC PATCH] efi: Provide wrappers for load_image, start_image, unload_image

[Julian Andres Klode]

These can be used to register a different implementation later,
for example, when shim provides a protocol with those functions.

---
 grub-core/kern/efi/efi.c           | 56 ++++++++++++++++++++++++++++++
 grub-core/loader/efi/chainloader.c | 13 +++----
 grub-core/loader/efi/linux.c       | 10 +++---
 include/grub/efi/efi.h             | 37 ++++++++++++++++++++
 4 files changed, 103 insertions(+), 13 deletions(-)

diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c
index a2afd8de9..cdc6f3605 100644
--- a/grub-core/kern/efi/efi.c
+++ b/grub-core/kern/efi/efi.c
@@ -1031,3 +1031,59 @@ grub_efi_compare_device_paths (const 
grub_efi_device_path_t *dp1,
 
   return 0;
 }
+
+static const grub_efi_loader_t *override_loader = NULL;
+grub_err_t
+grub_efi_register_loader (const grub_efi_loader_t *loader)
+{
+  if (override_loader != NULL)
+    return grub_error (GRUB_ERR_BUG, "trying to register different loader");
+  override_loader = loader;
+  return GRUB_ERR_NONE;
+}
+
+grub_err_t
+grub_efi_unregister_loader (const grub_efi_loader_t *loader)
+{
+  if (loader != override_loader)
+    return grub_error (GRUB_ERR_BUG, "trying to unregister different loader");
+
+  override_loader = NULL;
+  return GRUB_ERR_NONE;
+}
+
+grub_efi_status_t
+grub_efi_load_image (grub_efi_boolean_t boot_policy,
+                    grub_efi_handle_t parent_image_handle,
+                    grub_efi_device_path_t *file_path, void *source_buffer,
+                    grub_efi_uintn_t source_size,
+                    grub_efi_handle_t *image_handle)
+{
+  if (override_loader != NULL)
+    return override_loader->load_image (boot_policy, parent_image_handle,
+                                       file_path, source_buffer, source_size,
+                                       image_handle);
+  return grub_efi_system_table->boot_services->load_image (
+      boot_policy, parent_image_handle, file_path, source_buffer, source_size,
+      image_handle);
+}
+
+grub_efi_status_t
+grub_efi_start_image (grub_efi_handle_t image_handle,
+                     grub_efi_uintn_t *exit_data_size,
+                     grub_efi_char16_t **exit_data)
+{
+  if (override_loader != NULL)
+    return override_loader->start_image (image_handle, exit_data_size,
+                                        exit_data);
+  return grub_efi_system_table->boot_services->start_image (
+      image_handle, exit_data_size, exit_data);
+}
+
+grub_efi_status_t
+grub_efi_unload_image (grub_efi_handle_t image_handle)
+{
+  if (override_loader != NULL)
+    return override_loader->unload_image (image_handle);
+  return grub_efi_system_table->boot_services->unload_image (image_handle);
+}
diff --git a/grub-core/loader/efi/chainloader.c 
b/grub-core/loader/efi/chainloader.c
index 1de98f783..eb833b678 100644
--- a/grub-core/loader/efi/chainloader.c
+++ b/grub-core/loader/efi/chainloader.c
@@ -50,14 +50,12 @@ grub_chainloader_unload (void *context)
 {
   grub_efi_handle_t image_handle = (grub_efi_handle_t) context;
   grub_efi_loaded_image_t *loaded_image;
-  grub_efi_boot_services_t *b;
 
   loaded_image = grub_efi_get_loaded_image (image_handle);
   if (loaded_image != NULL)
     grub_free (loaded_image->load_options);
 
-  b = grub_efi_system_table->boot_services;
-  b->unload_image (image_handle);
+  grub_efi_unload_image (image_handle);
 
   grub_dl_unref (my_mod);
   return GRUB_ERR_NONE;
@@ -73,7 +71,7 @@ grub_chainloader_boot (void *context)
   grub_efi_char16_t *exit_data = NULL;
 
   b = grub_efi_system_table->boot_services;
-  status = b->start_image (image_handle, &exit_data_size, &exit_data);
+  status = grub_efi_start_image (image_handle, &exit_data_size, &exit_data);
   if (status != GRUB_EFI_SUCCESS)
     {
       if (exit_data)
@@ -343,9 +341,8 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ 
((unused)),
     }
 #endif
 
-  status = b->load_image (0, grub_efi_image_handle, file_path,
-                         boot_image, size,
-                         &image_handle);
+  status = grub_efi_load_image (0, grub_efi_image_handle, file_path,
+                               boot_image, size, &image_handle);
   if (status != GRUB_EFI_SUCCESS)
     {
       if (status == GRUB_EFI_OUT_OF_RESOURCES)
@@ -422,7 +419,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ 
((unused)),
     b->free_pages (address, pages);
 
   if (image_handle != NULL)
-    b->unload_image (image_handle);
+    grub_efi_unload_image (image_handle);
 
   grub_dl_unref (my_mod);
 
diff --git a/grub-core/loader/efi/linux.c b/grub-core/loader/efi/linux.c
index 43c4e2d3d..0e575b4eb 100644
--- a/grub-core/loader/efi/linux.c
+++ b/grub-core/loader/efi/linux.c
@@ -204,9 +204,9 @@ grub_arch_efi_linux_boot_image (grub_addr_t addr, 
grub_size_t size, char *args)
   mempath[1].header.length = sizeof (grub_efi_device_path_t);
 
   b = grub_efi_system_table->boot_services;
-  status = b->load_image (0, grub_efi_image_handle,
-                         (grub_efi_device_path_t *) mempath,
-                         (void *) addr, size, &image_handle);
+  status = grub_efi_load_image (0, grub_efi_image_handle,
+                               (grub_efi_device_path_t *)mempath,
+                               (void *)addr, size, &image_handle);
   if (status != GRUB_EFI_SUCCESS)
     return grub_error (GRUB_ERR_BAD_OS, "cannot load image");
 
@@ -231,14 +231,14 @@ grub_arch_efi_linux_boot_image (grub_addr_t addr, 
grub_size_t size, char *args)
                            (grub_uint8_t *) args, len, NULL);
 
   grub_dprintf ("linux", "starting image %p\n", image_handle);
-  status = b->start_image (image_handle, 0, NULL);
+  status = grub_efi_start_image (image_handle, 0, NULL);
 
   /* When successful, not reached */
   grub_error (GRUB_ERR_BAD_OS, "start_image() returned 0x%" 
PRIxGRUB_EFI_UINTN_T, status);
   grub_efi_free_pages ((grub_addr_t) loaded_image->load_options,
                       GRUB_EFI_BYTES_TO_PAGES 
(loaded_image->load_options_size));
 unload:
-  b->unload_image (image_handle);
+  grub_efi_unload_image (image_handle);
 
   return grub_errno;
 }
diff --git a/include/grub/efi/efi.h b/include/grub/efi/efi.h
index 572f7135f..a6aab7c13 100644
--- a/include/grub/efi/efi.h
+++ b/include/grub/efi/efi.h
@@ -129,6 +129,43 @@ grub_err_t 
grub_arch_efi_linux_load_image_header(grub_file_t file,
 grub_err_t grub_arch_efi_linux_boot_image(grub_addr_t addr, grub_size_t size,
                                            char *args);
 
+grub_efi_status_t 
+EXPORT_FUNC (grub_efi_load_image) (grub_efi_boolean_t boot_policy,
+                                  grub_efi_handle_t parent_image_handle,
+                                  grub_efi_device_path_t *file_path,
+                                  void *source_buffer, grub_efi_uintn_t 
source_size,
+                                  grub_efi_handle_t *image_handle);
+
+grub_efi_status_t
+EXPORT_FUNC (grub_efi_start_image) (grub_efi_handle_t image_handle,
+                                   grub_efi_uintn_t *exit_data_size,
+                                   grub_efi_char16_t **exit_data);
+
+grub_efi_status_t
+EXPORT_FUNC (grub_efi_unload_image) (grub_efi_handle_t image_handle);
+
+typedef struct grub_efi_loader
+{
+  grub_efi_status_t (*load_image) (grub_efi_boolean_t boot_policy,
+                                  grub_efi_handle_t parent_image_handle,
+                                  grub_efi_device_path_t *file_path,
+                                  void *source_buffer,
+                                  grub_efi_uintn_t source_size,
+                                  grub_efi_handle_t *image_handle);
+
+  grub_efi_status_t (*start_image) (grub_efi_handle_t image_handle,
+                                   grub_efi_uintn_t *exit_data_size,
+                                   grub_efi_char16_t **exit_data);
+
+  grub_efi_status_t (*unload_image) (grub_efi_handle_t image_handle);
+} grub_efi_loader_t;
+
+grub_err_t
+EXPORT_FUNC (grub_efi_register_loader) (const grub_efi_loader_t *loader);
+
+grub_err_t
+EXPORT_FUNC (grub_efi_unregister_loader) (const grub_efi_loader_t *loader);
+
 grub_addr_t grub_efi_section_addr (const char *section);
 
 void grub_efi_mm_init (void);
-- 
2.40.1