grub2/0265-efi-Provide-wrappers-for-load_image-start_image.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Julian Andres Klode <julian.klode@canonical.com>
Date: Tue, 9 Jul 2024 16:46:05 -0600
Subject: [PATCH] efi: Provide wrappers for load_image, start_image,

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

Signed-off-by: Mate Kukri <mate.kukri@canonical.com>
---
 grub-core/kern/efi/efi.c           | 57 ++++++++++++++++++++++++++++++++++++++
 grub-core/loader/efi/chainloader.c | 13 ++++-----
 include/grub/efi/efi.h             | 37 +++++++++++++++++++++++++
 3 files changed, 100 insertions(+), 7 deletions(-)

diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c
index cdfc11565c7..b5b8a329622 100644
--- a/grub-core/kern/efi/efi.c
+++ b/grub-core/kern/efi/efi.c
@@ -1131,6 +1131,63 @@ grub_efi_find_configuration_table (const grub_guid_t *target_guid)
   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);
+}
+
 grub_err_t
 grub_efi_status_to_err (grub_efi_status_t status)
 {
diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
index 5cd6f6a5993..9b1cc3fd41d 100644
--- a/grub-core/loader/efi/chainloader.c
+++ b/grub-core/loader/efi/chainloader.c
@@ -69,7 +69,7 @@ grub_start_image (grub_efi_handle_t handle)
 
   b = grub_efi_system_table->boot_services;
 
-  status = b->start_image (handle, &exit_data_size, &exit_data);
+  status = grub_efi_start_image (handle, &exit_data_size, &exit_data);
   if (status != GRUB_EFI_SUCCESS)
     {
       if (exit_data)
@@ -101,7 +101,6 @@ grub_chainloader_unload (void *context)
 {
   grub_efi_handle_t image_handle;
   grub_efi_loaded_image_t *loaded_image;
-  grub_efi_boot_services_t *b;
 
   image_handle = (grub_efi_handle_t) context;
 
@@ -109,8 +108,7 @@ grub_chainloader_unload (void *context)
   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;
@@ -871,8 +869,8 @@ grub_load_image(grub_efi_device_path_t *file_path, void *boot_image,
 
   b = grub_efi_system_table->boot_services;
 
-  status = b->load_image (0, grub_efi_image_handle, file_path,
-                          boot_image, image_size, image_handle_out);
+  status = grub_efi_load_image (0, grub_efi_image_handle, file_path,
+				boot_image, image_size, image_handle_out);
   if (status != GRUB_EFI_SUCCESS)
     {
       if (status == GRUB_EFI_OUT_OF_RESOURCES)
@@ -1198,7 +1196,8 @@ fail:
   if (cmdline)
     grub_free (cmdline);
 
-  b->unload_image (image_handle);
+  if (image_handle != NULL)
+    grub_efi_unload_image (image_handle);
 
   grub_dl_unref (my_mod);
 
diff --git a/include/grub/efi/efi.h b/include/grub/efi/efi.h
index 2c0e7f24bda..7eed1bd791d 100644
--- a/include/grub/efi/efi.h
+++ b/include/grub/efi/efi.h
@@ -202,6 +202,43 @@ grub_err_t grub_arch_efi_linux_load_image_header(grub_file_t file,
                                                 struct linux_arch_kernel_header *lh);
 grub_err_t grub_arch_efi_linux_boot_image(grub_addr_t addr, grub_size_t size,
 					  char *args, int nx_enabled);
+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 (__grub_efi_api *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 (__grub_efi_api *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 (__grub_efi_api *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);