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