arch/arm64/kernel/image.h

/*
 * Linker script macros to generate Image header fields.
 *
 * Copyright (C) 2014 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef __ASM_IMAGE_H
#define __ASM_IMAGE_H

#ifndef LINKER_SCRIPT
#error This file should only be included in vmlinux.lds.S
#endif

/*
 * There aren't any ELF relocations we can use to endian-swap values known only
 * at link time (e.g. the subtraction of two symbol addresses), so we must get
 * the linker to endian-swap certain values before emitting them.
 *
 * Note that, in order for this to work when building the ELF64 PIE executable
 * (for KASLR), these values should not be referenced via R_AARCH64_ABS64
 * relocations, since these are fixed up at runtime rather than at build time
 * when PIE is in effect. So we need to split them up in 32-bit high and low
 * words.
 */
#ifdef CONFIG_CPU_BIG_ENDIAN
#define DATA_LE32(data)				\
	((((data) & 0x000000ff) << 24) |	\
	 (((data) & 0x0000ff00) << 8)  |	\
	 (((data) & 0x00ff0000) >> 8)  |	\
	 (((data) & 0xff000000) >> 24))
#else
#define DATA_LE32(data) ((data) & 0xffffffff)
#endif

#define DEFINE_IMAGE_LE64(sym, data)				\
	sym##_lo32 = DATA_LE32((data) & 0xffffffff);		\
	sym##_hi32 = DATA_LE32((data) >> 32)

#ifdef CONFIG_CPU_BIG_ENDIAN
#define __HEAD_FLAG_BE		1
#else
#define __HEAD_FLAG_BE		0
#endif

#define __HEAD_FLAG_PAGE_SIZE	((PAGE_SHIFT - 10) / 2)

#define __HEAD_FLAG_PHYS_BASE	1

#define __HEAD_FLAGS		((__HEAD_FLAG_BE << 0) |	\
				 (__HEAD_FLAG_PAGE_SIZE << 1) |	\
				 (__HEAD_FLAG_PHYS_BASE << 3))

/*
 * These will output as part of the Image header, which should be little-endian
 * regardless of the endianness of the kernel. While constant values could be
 * endian swapped in head.S, all are done here for consistency.
 */
#define HEAD_SYMBOLS						\
	DEFINE_IMAGE_LE64(_kernel_size_le, _end - _text);	\
	DEFINE_IMAGE_LE64(_kernel_offset_le, TEXT_OFFSET);	\
	DEFINE_IMAGE_LE64(_kernel_flags_le, __HEAD_FLAGS);

#ifdef CONFIG_EFI

/*
 * Use ABSOLUTE() to avoid ld.lld treating this as a relative symbol:
 * https://github.com/ClangBuiltLinux/linux/issues/561
 */
__efistub_stext_offset = ABSOLUTE(stext - _text);

/*
 * The EFI stub has its own symbol namespace prefixed by __efistub_, to
 * isolate it from the kernel proper. The following symbols are legally
 * accessed by the stub, so provide some aliases to make them accessible.
 * Only include data symbols here, or text symbols of functions that are
 * guaranteed to be safe when executed at another offset than they were
 * linked at. The routines below are all implemented in assembler in a
 * position independent manner
 */
__efistub_memcmp		= __pi_memcmp;
__efistub_memchr		= __pi_memchr;
__efistub_memcpy		= __pi_memcpy;
__efistub_memmove		= __pi_memmove;
__efistub_memset		= __pi_memset;
__efistub_strlen		= __pi_strlen;
__efistub_strnlen		= __pi_strnlen;
__efistub_strcmp		= __pi_strcmp;
__efistub_strncmp		= __pi_strncmp;
__efistub_strrchr		= __pi_strrchr;
__efistub___flush_dcache_area	= __pi___flush_dcache_area;

#ifdef CONFIG_KASAN
__efistub___memcpy		= __pi_memcpy;
__efistub___memmove		= __pi_memmove;
__efistub___memset		= __pi_memset;
#endif

__efistub__text			= _text;
__efistub__end			= _end;
__efistub__edata		= _edata;
__efistub_screen_info		= screen_info;

#endif

#endif /* __ASM_IMAGE_H */