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@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, +};