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3bbd3db864
readelf complains about the section layout of vmlinux when building
with CONFIG_RELOCATABLE=y (for KASLR):
readelf: Warning: [21]: Link field (0) should index a symtab section.
readelf: Warning: [21]: Info field (0) should index a relocatable section.
Also, it seems that our use of '-pie -shared' is contradictory, and
thus ambiguous. In general, the way KASLR is wired up at the moment
is highly tailored to how ld.bfd happens to implement (and conflate)
PIE executables and shared libraries, so given the current effort to
support other toolchains, let's fix some of these issues as well.
- Drop the -pie linker argument and just leave -shared. In ld.bfd,
the differences between them are unclear (except for the ELF type
of the produced image [0]) but lld chokes on seeing both at the
same time.
- Rename the .rela output section to .rela.dyn, as is customary for
shared libraries and PIE executables, so that it is not misidentified
by readelf as a static relocation section (producing the warnings
above).
- Pass the -z notext and -z norelro options to explicitly instruct the
linker to permit text relocations, and to omit the RELRO program
header (which requires a certain section layout that we don't adhere
to in the kernel). These are the defaults for current versions of
ld.bfd.
- Discard .eh_frame and .gnu.hash sections to avoid them from being
emitted between .head.text and .text, screwing up the section layout.
These changes only affect the ELF image, and produce the same binary
image.
[0] b9dce7f1ba ("arm64: kernel: force ET_DYN ELF type for ...")
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Smith <peter.smith@linaro.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
268 lines
6.0 KiB
ArmAsm
268 lines
6.0 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* ld script to make ARM Linux kernel
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* taken from the i386 version by Russell King
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* Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
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*/
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#include <asm-generic/vmlinux.lds.h>
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#include <asm/cache.h>
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#include <asm/kernel-pgtable.h>
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#include <asm/thread_info.h>
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#include <asm/memory.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include "image.h"
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/* .exit.text needed in case of alternative patching */
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#define ARM_EXIT_KEEP(x) x
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#define ARM_EXIT_DISCARD(x)
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OUTPUT_ARCH(aarch64)
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ENTRY(_text)
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jiffies = jiffies_64;
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#define HYPERVISOR_TEXT \
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/* \
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* Align to 4 KB so that \
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* a) the HYP vector table is at its minimum \
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* alignment of 2048 bytes \
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* b) the HYP init code will not cross a page \
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* boundary if its size does not exceed \
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* 4 KB (see related ASSERT() below) \
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*/ \
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. = ALIGN(SZ_4K); \
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__hyp_idmap_text_start = .; \
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*(.hyp.idmap.text) \
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__hyp_idmap_text_end = .; \
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__hyp_text_start = .; \
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*(.hyp.text) \
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__hyp_text_end = .;
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#define IDMAP_TEXT \
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. = ALIGN(SZ_4K); \
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__idmap_text_start = .; \
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*(.idmap.text) \
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__idmap_text_end = .;
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#ifdef CONFIG_HIBERNATION
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#define HIBERNATE_TEXT \
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. = ALIGN(SZ_4K); \
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__hibernate_exit_text_start = .; \
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*(.hibernate_exit.text) \
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__hibernate_exit_text_end = .;
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#else
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#define HIBERNATE_TEXT
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#endif
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#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
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#define TRAMP_TEXT \
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. = ALIGN(PAGE_SIZE); \
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__entry_tramp_text_start = .; \
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*(.entry.tramp.text) \
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. = ALIGN(PAGE_SIZE); \
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__entry_tramp_text_end = .;
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#else
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#define TRAMP_TEXT
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#endif
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/*
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* The size of the PE/COFF section that covers the kernel image, which
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* runs from stext to _edata, must be a round multiple of the PE/COFF
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* FileAlignment, which we set to its minimum value of 0x200. 'stext'
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* itself is 4 KB aligned, so padding out _edata to a 0x200 aligned
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* boundary should be sufficient.
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*/
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PECOFF_FILE_ALIGNMENT = 0x200;
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#ifdef CONFIG_EFI
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#define PECOFF_EDATA_PADDING \
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.pecoff_edata_padding : { BYTE(0); . = ALIGN(PECOFF_FILE_ALIGNMENT); }
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#else
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#define PECOFF_EDATA_PADDING
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#endif
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SECTIONS
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{
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/*
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* XXX: The linker does not define how output sections are
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* assigned to input sections when there are multiple statements
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* matching the same input section name. There is no documented
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* order of matching.
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*/
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/DISCARD/ : {
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ARM_EXIT_DISCARD(EXIT_TEXT)
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ARM_EXIT_DISCARD(EXIT_DATA)
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EXIT_CALL
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*(.discard)
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*(.discard.*)
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*(.interp .dynamic)
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*(.dynsym .dynstr .hash .gnu.hash)
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*(.eh_frame)
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}
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. = KIMAGE_VADDR + TEXT_OFFSET;
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.head.text : {
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_text = .;
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HEAD_TEXT
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}
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.text : { /* Real text segment */
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_stext = .; /* Text and read-only data */
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__exception_text_start = .;
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*(.exception.text)
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__exception_text_end = .;
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IRQENTRY_TEXT
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SOFTIRQENTRY_TEXT
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ENTRY_TEXT
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TEXT_TEXT
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SCHED_TEXT
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CPUIDLE_TEXT
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LOCK_TEXT
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KPROBES_TEXT
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HYPERVISOR_TEXT
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IDMAP_TEXT
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HIBERNATE_TEXT
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TRAMP_TEXT
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*(.fixup)
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*(.gnu.warning)
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. = ALIGN(16);
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*(.got) /* Global offset table */
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}
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. = ALIGN(SEGMENT_ALIGN);
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_etext = .; /* End of text section */
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RO_DATA(PAGE_SIZE) /* everything from this point to */
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EXCEPTION_TABLE(8) /* __init_begin will be marked RO NX */
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NOTES
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. = ALIGN(PAGE_SIZE);
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idmap_pg_dir = .;
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. += IDMAP_DIR_SIZE;
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#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
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tramp_pg_dir = .;
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. += PAGE_SIZE;
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#endif
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#ifdef CONFIG_ARM64_SW_TTBR0_PAN
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reserved_ttbr0 = .;
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. += RESERVED_TTBR0_SIZE;
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#endif
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swapper_pg_dir = .;
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. += PAGE_SIZE;
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swapper_pg_end = .;
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. = ALIGN(SEGMENT_ALIGN);
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__init_begin = .;
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__inittext_begin = .;
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INIT_TEXT_SECTION(8)
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.exit.text : {
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ARM_EXIT_KEEP(EXIT_TEXT)
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}
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. = ALIGN(4);
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.altinstructions : {
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__alt_instructions = .;
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*(.altinstructions)
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__alt_instructions_end = .;
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}
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.altinstr_replacement : {
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*(.altinstr_replacement)
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}
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. = ALIGN(PAGE_SIZE);
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__inittext_end = .;
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__initdata_begin = .;
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.init.data : {
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INIT_DATA
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INIT_SETUP(16)
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INIT_CALLS
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CON_INITCALL
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INIT_RAM_FS
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*(.init.rodata.* .init.bss) /* from the EFI stub */
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}
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.exit.data : {
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ARM_EXIT_KEEP(EXIT_DATA)
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}
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PERCPU_SECTION(L1_CACHE_BYTES)
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.rela.dyn : ALIGN(8) {
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*(.rela .rela*)
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}
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__rela_offset = ABSOLUTE(ADDR(.rela.dyn) - KIMAGE_VADDR);
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__rela_size = SIZEOF(.rela.dyn);
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. = ALIGN(SEGMENT_ALIGN);
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__initdata_end = .;
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__init_end = .;
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_data = .;
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_sdata = .;
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RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_ALIGN)
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/*
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* Data written with the MMU off but read with the MMU on requires
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* cache lines to be invalidated, discarding up to a Cache Writeback
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* Granule (CWG) of data from the cache. Keep the section that
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* requires this type of maintenance to be in its own Cache Writeback
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* Granule (CWG) area so the cache maintenance operations don't
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* interfere with adjacent data.
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*/
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.mmuoff.data.write : ALIGN(SZ_2K) {
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__mmuoff_data_start = .;
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*(.mmuoff.data.write)
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}
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. = ALIGN(SZ_2K);
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.mmuoff.data.read : {
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*(.mmuoff.data.read)
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__mmuoff_data_end = .;
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}
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PECOFF_EDATA_PADDING
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__pecoff_data_rawsize = ABSOLUTE(. - __initdata_begin);
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_edata = .;
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BSS_SECTION(0, 0, 0)
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. = ALIGN(PAGE_SIZE);
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init_pg_dir = .;
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. += INIT_DIR_SIZE;
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init_pg_end = .;
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__pecoff_data_size = ABSOLUTE(. - __initdata_begin);
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_end = .;
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STABS_DEBUG
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HEAD_SYMBOLS
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}
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/*
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* The HYP init code and ID map text can't be longer than a page each,
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* and should not cross a page boundary.
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*/
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ASSERT(__hyp_idmap_text_end - (__hyp_idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
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"HYP init code too big or misaligned")
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ASSERT(__idmap_text_end - (__idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K,
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"ID map text too big or misaligned")
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#ifdef CONFIG_HIBERNATION
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ASSERT(__hibernate_exit_text_end - (__hibernate_exit_text_start & ~(SZ_4K - 1))
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<= SZ_4K, "Hibernate exit text too big or misaligned")
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#endif
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#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
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ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE,
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"Entry trampoline text too big")
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#endif
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/*
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* If padding is applied before .head.text, virt<->phys conversions will fail.
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*/
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ASSERT(_text == (KIMAGE_VADDR + TEXT_OFFSET), "HEAD is misaligned")
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