[U-Boot] [PATCH 6/9] efi_loader: Add runtime services

[Alexander Graf]

After booting has finished, EFI allows firmware to still interact with the OS
using the "runtime services". These callbacks live in a separate address space,
since they are available long after U-Boot has been overwritten by the OS.

However, since U-Boot has no notion of RTS, we just create an extremely minimal
RTS stub that just declares all functions as unsupported. We could in the future
map U-boot environment variables to EFI variables here.

Signed-off-by: Alexander Graf <agraf at suse.de>
---
 arch/arm/cpu/armv8/u-boot.lds |  8 ++++++
 arch/arm/cpu/u-boot.lds       | 13 ++++++++++
 arch/arm/lib/sections.c       |  2 ++
 include/efi_loader.h          |  3 +++
 lib/efi_loader/efi_runtime.c  | 59 +++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 85 insertions(+)
 create mode 100644 lib/efi_loader/efi_runtime.c

diff --git a/arch/arm/cpu/armv8/u-boot.lds b/arch/arm/cpu/armv8/u-boot.lds
index 4c12222..7c5b032 100644
--- a/arch/arm/cpu/armv8/u-boot.lds
+++ b/arch/arm/cpu/armv8/u-boot.lds
@@ -42,6 +42,14 @@ SECTIONS
 
 	. = ALIGN(8);
 
+	.efi_runtime : {
+                __efi_runtime_start = .;
+		*(efi_runtime)
+                __efi_runtime_stop = .;
+	}
+
+	. = ALIGN(8);
+
 	.image_copy_end :
 	{
 		*(.__image_copy_end)
diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds
index d48a905..b5198d0 100644
--- a/arch/arm/cpu/u-boot.lds
+++ b/arch/arm/cpu/u-boot.lds
@@ -89,6 +89,19 @@ SECTIONS
 
 	. = ALIGN(4);
 
+	.__efi_runtime_start : {
+		*(.__efi_runtime_start)
+	}
+
+	.efi_runtime : {
+		*(efi_runtime)
+	}
+
+	.__efi_runtime_stop : {
+		*(.__efi_runtime_stop)
+	}
+	. = ALIGN(4);
+
 	.image_copy_end :
 	{
 		*(.__image_copy_end)
diff --git a/arch/arm/lib/sections.c b/arch/arm/lib/sections.c
index a1205c3..21b3066 100644
--- a/arch/arm/lib/sections.c
+++ b/arch/arm/lib/sections.c
@@ -27,4 +27,6 @@ char __rel_dyn_start[0] __attribute__((section(".__rel_dyn_start")));
 char __rel_dyn_end[0] __attribute__((section(".__rel_dyn_end")));
 char __secure_start[0] __attribute__((section(".__secure_start")));
 char __secure_end[0] __attribute__((section(".__secure_end")));
+char __efi_runtime_start[0] __attribute__((section(".__efi_runtime_start")));
+char __efi_runtime_stop[0] __attribute__((section(".__efi_runtime_stop")));
 char _end[0] __attribute__((section(".__end")));
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 7fb2106..af1c88f 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -39,6 +39,7 @@
 
 #define EFI_EXIT(ret) efi_exit_func(ret);
 
+extern const struct efi_runtime_services efi_runtime_services;
 extern struct efi_system_table systab;
 
 extern const struct efi_simple_text_output_protocol efi_con_out;
@@ -49,6 +50,8 @@ 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;
 
+extern unsigned int __efi_runtime_start, __efi_runtime_stop;
+
 struct efi_class_map {
 	const efi_guid_t *guid;
 	const void *interface;
diff --git a/lib/efi_loader/efi_runtime.c b/lib/efi_loader/efi_runtime.c
new file mode 100644
index 0000000..214e1f5
--- /dev/null
+++ b/lib/efi_loader/efi_runtime.c
@@ -0,0 +1,59 @@
+/*
+ *  EFI application runtime services
+ *
+ *  Copyright (c) 2015 Alexander Graf
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ *
+ *  SPDX-License-Identifier:     LGPL-2.1+
+ */
+
+#include <common.h>
+#include <efi_loader.h>
+
+/*
+ * EFI Runtime code is still alive when U-Boot is long overwritten. To isolate
+ * this code from the rest, we put it into a special section.
+ *
+ *        !!WARNING!!
+ *
+ * This means that we can not rely on any code outside of this file at runtime.
+ * Please keep it fully self-contained.
+ */
+asm(".section efi_runtime,\"a\"");
+
+static efi_status_t efi_unimplemented(void)
+{
+	return EFI_UNSUPPORTED;
+}
+
+const struct efi_runtime_services efi_runtime_services = {
+	.hdr = {
+		.signature = EFI_RUNTIME_SERVICES_SIGNATURE,
+		.revision = EFI_RUNTIME_SERVICES_REVISION,
+		.headersize = sizeof(struct efi_table_hdr),
+	},
+	.get_time = (void *)&efi_unimplemented,
+	.set_time = (void *)&efi_unimplemented,
+	.get_wakeup_time = (void *)&efi_unimplemented,
+	.set_wakeup_time = (void *)&efi_unimplemented,
+	.set_virtual_address_map = (void *)&efi_unimplemented,
+	.convert_pointer = (void *)&efi_unimplemented,
+	.get_variable = (void *)&efi_unimplemented,
+	.get_next_variable = (void *)&efi_unimplemented,
+	.set_variable = (void *)&efi_unimplemented,
+	.get_next_high_mono_count = (void *)&efi_unimplemented,
+	.reset_system = (void *)&efi_unimplemented,
+};
-- 
2.1.4