forked from Minki/linux
6ad1fe5d90
Unfortunately, the current way of using the linker to emit build time constants into the Image header will no longer work once we switch to the use of PIE executables. The reason is that such constants are emitted into the binary using R_AARCH64_ABS64 relocations, which are resolved at runtime, not at build time, and the places targeted by those relocations will contain zeroes before that. So refactor the endian swapping linker script constant generation code so that it emits the upper and lower 32-bit words separately. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
118 lines
4.2 KiB
C
118 lines
4.2 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_IMAGE_H
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#define __ASM_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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/*
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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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#ifdef CONFIG_CPU_BIG_ENDIAN
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#define __HEAD_FLAG_BE 1
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#else
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#define __HEAD_FLAG_BE 0
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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 << 0) | \
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(__HEAD_FLAG_PAGE_SIZE << 1) | \
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(__HEAD_FLAG_PHYS_BASE << 3))
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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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#ifdef CONFIG_EFI
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/*
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* Prevent the symbol aliases below from being emitted into the kallsyms
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* table, by forcing them to be absolute symbols (which are conveniently
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* ignored by scripts/kallsyms) rather than section relative symbols.
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* The distinction is only relevant for partial linking, and only for symbols
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* that are defined within a section declaration (which is not the case for
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* the definitions below) so the resulting values will be identical.
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*/
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#define KALLSYMS_HIDE(sym) ABSOLUTE(sym)
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/*
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* The EFI stub has its own symbol namespace prefixed by __efistub_, to
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* isolate it from the kernel proper. The following symbols are legally
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* accessed by the stub, so provide some aliases to make them accessible.
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* Only include data symbols here, or text symbols of functions that are
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* guaranteed to be safe when executed at another offset than they were
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* linked at. The routines below are all implemented in assembler in a
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* position independent manner
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*/
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__efistub_memcmp = KALLSYMS_HIDE(__pi_memcmp);
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__efistub_memchr = KALLSYMS_HIDE(__pi_memchr);
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__efistub_memcpy = KALLSYMS_HIDE(__pi_memcpy);
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__efistub_memmove = KALLSYMS_HIDE(__pi_memmove);
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__efistub_memset = KALLSYMS_HIDE(__pi_memset);
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__efistub_strlen = KALLSYMS_HIDE(__pi_strlen);
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__efistub_strcmp = KALLSYMS_HIDE(__pi_strcmp);
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__efistub_strncmp = KALLSYMS_HIDE(__pi_strncmp);
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__efistub___flush_dcache_area = KALLSYMS_HIDE(__pi___flush_dcache_area);
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#ifdef CONFIG_KASAN
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__efistub___memcpy = KALLSYMS_HIDE(__pi_memcpy);
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__efistub___memmove = KALLSYMS_HIDE(__pi_memmove);
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__efistub___memset = KALLSYMS_HIDE(__pi_memset);
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#endif
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__efistub__text = KALLSYMS_HIDE(_text);
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__efistub__end = KALLSYMS_HIDE(_end);
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__efistub__edata = KALLSYMS_HIDE(_edata);
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#endif
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#endif /* __ASM_IMAGE_H */
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