u-boot-brain/arch/arm/lib/sections.c
Alexander Graf 50149ea37a efi_loader: Add runtime services
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.

This patch adds enough framework for arbitrary code inside of U-Boot to become
a runtime service with the right section attributes set. For now, we don't make
use of it yet though.

We could maybe in the future map U-boot environment variables to EFI variables
here.

Signed-off-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-03-15 18:03:10 -04:00

35 lines
1.7 KiB
C

/*
* Copyright 2013 Albert ARIBAUD <albert.u.boot@aribaud.net>
*
* SPDX-License-Identifier: GPL-2.0+
*/
/**
* These two symbols are declared in a C file so that the linker
* uses R_ARM_RELATIVE relocation, rather than the R_ARM_ABS32 one
* it would use if the symbols were defined in the linker file.
* Using only R_ARM_RELATIVE relocation ensures that references to
* the symbols are correct after as well as before relocation.
*
* We need a 0-byte-size type for these symbols, and the compiler
* does not allow defining objects of C type 'void'. Using an empty
* struct is allowed by the compiler, but causes gcc versions 4.4 and
* below to complain about aliasing. Therefore we use the next best
* thing: zero-sized arrays, which are both 0-byte-size and exempt from
* aliasing warnings.
*/
char __bss_start[0] __attribute__((section(".__bss_start")));
char __bss_end[0] __attribute__((section(".__bss_end")));
char __image_copy_start[0] __attribute__((section(".__image_copy_start")));
char __image_copy_end[0] __attribute__((section(".__image_copy_end")));
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 __efi_runtime_rel_start[0] __attribute__((section(".__efi_runtime_rel_start")));
char __efi_runtime_rel_stop[0] __attribute__((section(".__efi_runtime_rel_stop")));
char _end[0] __attribute__((section(".__end")));