[U-Boot] [PATCH 1/1] bootefi: allow return without EFI_BOOT_SERVICES.Exit

[Heinrich Schuchardt]

The Unified Extensible Firmware Interface Specification, version 2.7,
defines in chapter 2.1.2 - UEFI Application that an EFI application may
either directly return or call EFI_BOOT_SERVICES.Exit().

Unfortunately U-Boot makes the incorrect assumption that
EFI_BOOT_SERVICES.Exit() is always called.

So the following application leads to a memory exception on the aarch64
architecture when returning:

EFI_STATUS efi_main(
  EFI_HANDLE handle,
  EFI_SYSTEM_TABlE systable) {
	return EFI_SUCCESS;
}

With this patch the entry point is stored in the image handle.

The new wrapper function do_enter is used to call the EFI entry point.

Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 cmd/bootefi.c     | 18 ++++++++++++++++--
 include/efi_api.h |  4 ++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index a0a5434967..fcb223e999 100644
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -9,6 +9,7 @@
 #include <common.h>
 #include <command.h>
 #include <dm.h>
+#include <efi_api.h>
 #include <efi_loader.h>
 #include <errno.h>
 #include <libfdt.h>
@@ -141,6 +142,18 @@ static void *copy_fdt(void *fdt)
 	return new_fdt;
 }
 
+static asmlinkage ulong do_enter(void *image_handle,
+				 struct efi_system_table *st)
+{
+	struct efi_loaded_image *handle = image_handle;
+	efi_status_t ret = EFI_LOAD_ERROR;
+
+	if (handle->entry)
+		ret = handle->entry(image_handle, st);
+	st->boottime->exit(image_handle, ret, 0 , NULL);
+	return ret;
+}
+
 #ifdef CONFIG_ARM64
 static unsigned long efi_run_in_el2(ulong (*entry)(void *image_handle,
 		struct efi_system_table *st), void *image_handle,
@@ -149,7 +162,7 @@ static unsigned long efi_run_in_el2(ulong (*entry)(void *image_handle,
 	/* Enable caches again */
 	dcache_enable();
 
-	return entry(image_handle, st);
+	return do_enter(image_handle, st);
 }
 #endif
 
@@ -237,6 +250,7 @@ static unsigned long do_bootefi_exec(void *efi, void *fdt)
 		efi_status_t status = loaded_image_info.exit_status;
 		return status == EFI_SUCCESS ? 0 : -EINVAL;
 	}
+	loaded_image_info.entry = entry;
 
 #ifdef CONFIG_ARM64
 	/* On AArch64 we need to make sure we call our payload in < EL3 */
@@ -254,7 +268,7 @@ static unsigned long do_bootefi_exec(void *efi, void *fdt)
 	}
 #endif
 
-	return entry(&loaded_image_info, &systab);
+	return do_enter(&loaded_image_info, &systab);
 }
 
 
diff --git a/include/efi_api.h b/include/efi_api.h
index 5c3836a51b..611c35c422 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -253,6 +253,10 @@ struct efi_loaded_image {
 	efi_status_t exit_status;
 	struct jmp_buf_data exit_jmp;
 #endif
+#ifdef CONFIG_CMD_BOOTEFI
+	ulong (*entry)(void *image_handle, struct efi_system_table *st)
+		asmlinkage;
+#endif
 };
 
 #define DEVICE_PATH_GUID \
-- 
2.11.0