efi_loader: check tables in helloworld.efi

Check if the device tree and the SMBIOS table are available.
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: NAlexander Graf <agraf@suse.de>

lib/efi_loader/helloworld.c

@@ -14,6 +14,22 @@
 #include <efi_api.h>
 
 static const efi_guid_t loaded_image_guid = LOADED_IMAGE_GUID;
+static const efi_guid_t fdt_guid = EFI_FDT_GUID;
+static const efi_guid_t smbios_guid = SMBIOS_TABLE_GUID;
+
+static int hw_memcmp(const void *buf1, const void *buf2, size_t length)
+{
+	const u8 *pos1 = buf1;
+	const u8 *pos2 = buf2;
+
+	for (; length; --length) {
+		if (*pos1 != *pos2)
+			return *pos1 - *pos2;
+		++pos1;
+		++pos2;
+	}
+	return 0;
+}
 
 /*
  * Entry point of the EFI application.
@@ -29,6 +45,7 @@ efi_status_t EFIAPI efi_main(efi_handle_t handle,
 	struct efi_boot_services *boottime = systable->boottime;
 	struct efi_loaded_image *loaded_image;
 	efi_status_t ret;
+	efi_uintn_t i;
 
 	con_out->output_string(con_out, L"Hello, world!\n");
 
@@ -40,6 +57,15 @@ efi_status_t EFIAPI efi_main(efi_handle_t handle,
 				       L"Cannot open loaded image protocol\n");
 		goto out;
 	}
+	/* Find configuration tables */
+	for (i = 0; i < systable->nr_tables; ++i) {
+		if (!hw_memcmp(&systable->tables[i].guid, &fdt_guid,
+			       sizeof(efi_guid_t)))
+			con_out->output_string(con_out, L"Have device tree\n");
+		if (!hw_memcmp(&systable->tables[i].guid, &smbios_guid,
+			       sizeof(efi_guid_t)))
+			con_out->output_string(con_out, L"Have SMBIOS table\n");
+	}
 	/* Output the load options */
 	con_out->output_string(con_out, L"Load options: ");
 	if (loaded_image->load_options_size && loaded_image->load_options)