37cb02da44
[ Upstream commit aa69fb62bea15126e744af2e02acc0d6cf3ed4da ] After r363059 and r363928 in LLVM, a build using ld.lld as the linker with CONFIG_RANDOMIZE_BASE enabled fails like so: ld.lld: error: relocation R_AARCH64_ABS32 cannot be used against symbol __efistub_stext_offset; recompile with -fPIC Fangrui and Peter figured out that ld.lld is incorrectly considering __efistub_stext_offset as a relative symbol because of the order in which symbols are evaluated. _text is treated as an absolute symbol and stext is a relative symbol, making __efistub_stext_offset a relative symbol. Adding ABSOLUTE will force ld.lld to evalute this expression in the right context and does not change ld.bfd's behavior. ld.lld will need to be fixed but the developers do not see a quick or simple fix without some research (see the linked issue for further explanation). Add this simple workaround so that ld.lld can continue to link kernels. Link: https://github.com/ClangBuiltLinux/linux/issues/561 Link:025a815d75Link:249fde8583Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Debugged-by: Fangrui Song <maskray@google.com> Debugged-by: Peter Smith <peter.smith@linaro.org> Suggested-by: Fangrui Song <maskray@google.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> [will: add comment] Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
117 lines
3.8 KiB
C
117 lines
3.8 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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* Use ABSOLUTE() to avoid ld.lld treating this as a relative symbol:
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* https://github.com/ClangBuiltLinux/linux/issues/561
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*/
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__efistub_stext_offset = ABSOLUTE(stext - _text);
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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 = __pi_memcmp;
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__efistub_memchr = __pi_memchr;
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__efistub_memcpy = __pi_memcpy;
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__efistub_memmove = __pi_memmove;
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__efistub_memset = __pi_memset;
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__efistub_strlen = __pi_strlen;
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__efistub_strnlen = __pi_strnlen;
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__efistub_strcmp = __pi_strcmp;
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__efistub_strncmp = __pi_strncmp;
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__efistub_strrchr = __pi_strrchr;
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__efistub___flush_dcache_area = __pi___flush_dcache_area;
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#ifdef CONFIG_KASAN
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__efistub___memcpy = __pi_memcpy;
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__efistub___memmove = __pi_memmove;
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__efistub___memset = __pi_memset;
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#endif
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__efistub__text = _text;
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__efistub__end = _end;
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__efistub__edata = _edata;
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__efistub_screen_info = screen_info;
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#endif
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#endif /* __ASM_IMAGE_H */
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