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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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