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90776dd1c4
It seems that LLVM's linker does not correctly handle variable assignments involving section positions that are updated during the SECTIONS parsing. Commitaa69fb62be
("arm64/efi: Mark __efistub_stext_offset as an absolute symbol explicitly") ran into this too, but found a different workaround. However, this was not enough, as other variables were also miscalculated which manifested as boot failures under UEFI where __efistub__end was not taking the correct _end value (they should be the same): $ ld.lld -EL -maarch64elf --no-undefined -X -shared \ -Bsymbolic -z notext -z norelro --no-apply-dynamic-relocs \ -o vmlinux.lld -T poc.lds --whole-archive vmlinux.o && \ readelf -Ws vmlinux.lld | egrep '\b(__efistub_|)_end\b' 368272: ffff000002218000 0 NOTYPE LOCAL HIDDEN 38 __efistub__end 368322: ffff000012318000 0 NOTYPE GLOBAL DEFAULT 38 _end $ aarch64-linux-gnu-ld.bfd -EL -maarch64elf --no-undefined -X -shared \ -Bsymbolic -z notext -z norelro --no-apply-dynamic-relocs \ -o vmlinux.bfd -T poc.lds --whole-archive vmlinux.o && \ readelf -Ws vmlinux.bfd | egrep '\b(__efistub_|)_end\b' 338124: ffff000012318000 0 NOTYPE LOCAL DEFAULT ABS __efistub__end 383812: ffff000012318000 0 NOTYPE GLOBAL DEFAULT 15325 _end To work around this, all of the __efistub_-prefixed variable assignments need to be moved after the linker script's SECTIONS entry. As it turns out, this also solves the problem fixed in commitaa69fb62be
, so those changes are reverted here. Link: https://github.com/ClangBuiltLinux/linux/issues/634 Link: https://bugs.llvm.org/show_bug.cgi?id=42990 Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Will Deacon <will@kernel.org>
69 lines
2.1 KiB
C
69 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Linker script macros to generate Image header fields.
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*
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* Copyright (C) 2014 ARM Ltd.
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*/
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#ifndef __ARM64_KERNEL_IMAGE_H
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#define __ARM64_KERNEL_IMAGE_H
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#ifndef LINKER_SCRIPT
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#error This file should only be included in vmlinux.lds.S
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#endif
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#include <asm/image.h>
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/*
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* There aren't any ELF relocations we can use to endian-swap values known only
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* at link time (e.g. the subtraction of two symbol addresses), so we must get
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* the linker to endian-swap certain values before emitting them.
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*
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* Note that, in order for this to work when building the ELF64 PIE executable
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* (for KASLR), these values should not be referenced via R_AARCH64_ABS64
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* relocations, since these are fixed up at runtime rather than at build time
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* when PIE is in effect. So we need to split them up in 32-bit high and low
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* words.
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*/
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#ifdef CONFIG_CPU_BIG_ENDIAN
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#define DATA_LE32(data) \
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((((data) & 0x000000ff) << 24) | \
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(((data) & 0x0000ff00) << 8) | \
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(((data) & 0x00ff0000) >> 8) | \
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(((data) & 0xff000000) >> 24))
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#else
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#define DATA_LE32(data) ((data) & 0xffffffff)
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#endif
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#define DEFINE_IMAGE_LE64(sym, data) \
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sym##_lo32 = DATA_LE32((data) & 0xffffffff); \
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sym##_hi32 = DATA_LE32((data) >> 32)
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#define __HEAD_FLAG(field) (__HEAD_FLAG_##field << \
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ARM64_IMAGE_FLAG_##field##_SHIFT)
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#ifdef CONFIG_CPU_BIG_ENDIAN
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#define __HEAD_FLAG_BE ARM64_IMAGE_FLAG_BE
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#else
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#define __HEAD_FLAG_BE ARM64_IMAGE_FLAG_LE
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#endif
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#define __HEAD_FLAG_PAGE_SIZE ((PAGE_SHIFT - 10) / 2)
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#define __HEAD_FLAG_PHYS_BASE 1
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#define __HEAD_FLAGS (__HEAD_FLAG(BE) | \
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__HEAD_FLAG(PAGE_SIZE) | \
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__HEAD_FLAG(PHYS_BASE))
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/*
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* These will output as part of the Image header, which should be little-endian
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* regardless of the endianness of the kernel. While constant values could be
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* endian swapped in head.S, all are done here for consistency.
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*/
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#define HEAD_SYMBOLS \
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DEFINE_IMAGE_LE64(_kernel_size_le, _end - _text); \
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DEFINE_IMAGE_LE64(_kernel_offset_le, TEXT_OFFSET); \
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DEFINE_IMAGE_LE64(_kernel_flags_le, __HEAD_FLAGS);
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#endif /* __ARM64_KERNEL_IMAGE_H */
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