![Josh Poimboeuf](/assets/img/avatar_default.png)
The '__unreachable' and '__func_stack_frame_non_standard' sections are
only used at compile time. They're discarded for vmlinux but they
should also be discarded for modules.
Since this is a recurring pattern, prefix the section names with
".discard.". It's a nice convention and vmlinux.lds.h already discards
such sections.
Also remove the 'a' (allocatable) flag from the __unreachable section
since it doesn't make sense for a discarded section.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: d1091c7fa3
("objtool: Improve detection of BUG() and other dead ends")
Link: http://lkml.kernel.org/r/20170301180444.lhd53c5tibc4ns77@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
387 lines
9.1 KiB
ArmAsm
387 lines
9.1 KiB
ArmAsm
/*
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* ld script for the x86 kernel
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*
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* Historic 32-bit version written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
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*
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* Modernisation, unification and other changes and fixes:
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* Copyright (C) 2007-2009 Sam Ravnborg <sam@ravnborg.org>
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*
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*
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* Don't define absolute symbols until and unless you know that symbol
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* value is should remain constant even if kernel image is relocated
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* at run time. Absolute symbols are not relocated. If symbol value should
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* change if kernel is relocated, make the symbol section relative and
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* put it inside the section definition.
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*/
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#ifdef CONFIG_X86_32
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#define LOAD_OFFSET __PAGE_OFFSET
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#else
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#define LOAD_OFFSET __START_KERNEL_map
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#endif
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#include <asm-generic/vmlinux.lds.h>
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#include <asm/asm-offsets.h>
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#include <asm/thread_info.h>
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#include <asm/page_types.h>
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#include <asm/cache.h>
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#include <asm/boot.h>
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#undef i386 /* in case the preprocessor is a 32bit one */
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OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT)
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#ifdef CONFIG_X86_32
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OUTPUT_ARCH(i386)
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ENTRY(phys_startup_32)
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jiffies = jiffies_64;
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#else
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OUTPUT_ARCH(i386:x86-64)
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ENTRY(phys_startup_64)
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jiffies_64 = jiffies;
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#endif
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#if defined(CONFIG_X86_64)
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/*
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* On 64-bit, align RODATA to 2MB so we retain large page mappings for
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* boundaries spanning kernel text, rodata and data sections.
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*
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* However, kernel identity mappings will have different RWX permissions
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* to the pages mapping to text and to the pages padding (which are freed) the
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* text section. Hence kernel identity mappings will be broken to smaller
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* pages. For 64-bit, kernel text and kernel identity mappings are different,
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* so we can enable protection checks as well as retain 2MB large page
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* mappings for kernel text.
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*/
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#define X64_ALIGN_RODATA_BEGIN . = ALIGN(HPAGE_SIZE);
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#define X64_ALIGN_RODATA_END \
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. = ALIGN(HPAGE_SIZE); \
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__end_rodata_hpage_align = .;
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#else
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#define X64_ALIGN_RODATA_BEGIN
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#define X64_ALIGN_RODATA_END
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#endif
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PHDRS {
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text PT_LOAD FLAGS(5); /* R_E */
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data PT_LOAD FLAGS(6); /* RW_ */
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#ifdef CONFIG_X86_64
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#ifdef CONFIG_SMP
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percpu PT_LOAD FLAGS(6); /* RW_ */
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#endif
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init PT_LOAD FLAGS(7); /* RWE */
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#endif
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note PT_NOTE FLAGS(0); /* ___ */
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}
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SECTIONS
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{
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#ifdef CONFIG_X86_32
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. = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;
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phys_startup_32 = ABSOLUTE(startup_32 - LOAD_OFFSET);
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#else
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. = __START_KERNEL;
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phys_startup_64 = ABSOLUTE(startup_64 - LOAD_OFFSET);
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#endif
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/* Text and read-only data */
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.text : AT(ADDR(.text) - LOAD_OFFSET) {
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_text = .;
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_stext = .;
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/* bootstrapping code */
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HEAD_TEXT
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. = ALIGN(8);
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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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ENTRY_TEXT
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IRQENTRY_TEXT
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SOFTIRQENTRY_TEXT
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*(.fixup)
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*(.gnu.warning)
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/* End of text section */
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_etext = .;
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} :text = 0x9090
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NOTES :text :note
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EXCEPTION_TABLE(16) :text = 0x9090
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/* .text should occupy whole number of pages */
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. = ALIGN(PAGE_SIZE);
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X64_ALIGN_RODATA_BEGIN
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RO_DATA(PAGE_SIZE)
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X64_ALIGN_RODATA_END
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/* Data */
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.data : AT(ADDR(.data) - LOAD_OFFSET) {
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/* Start of data section */
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_sdata = .;
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/* init_task */
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INIT_TASK_DATA(THREAD_SIZE)
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#ifdef CONFIG_X86_32
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/* 32 bit has nosave before _edata */
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NOSAVE_DATA
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#endif
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PAGE_ALIGNED_DATA(PAGE_SIZE)
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CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES)
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DATA_DATA
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CONSTRUCTORS
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/* rarely changed data like cpu maps */
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READ_MOSTLY_DATA(INTERNODE_CACHE_BYTES)
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/* End of data section */
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_edata = .;
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} :data
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. = ALIGN(PAGE_SIZE);
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__vvar_page = .;
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.vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
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/* work around gold bug 13023 */
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__vvar_beginning_hack = .;
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/* Place all vvars at the offsets in asm/vvar.h. */
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#define EMIT_VVAR(name, offset) \
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. = __vvar_beginning_hack + offset; \
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*(.vvar_ ## name)
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#define __VVAR_KERNEL_LDS
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#include <asm/vvar.h>
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#undef __VVAR_KERNEL_LDS
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#undef EMIT_VVAR
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/*
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* Pad the rest of the page with zeros. Otherwise the loader
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* can leave garbage here.
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*/
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. = __vvar_beginning_hack + PAGE_SIZE;
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} :data
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. = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
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/* Init code and data - will be freed after init */
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. = ALIGN(PAGE_SIZE);
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.init.begin : AT(ADDR(.init.begin) - LOAD_OFFSET) {
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__init_begin = .; /* paired with __init_end */
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}
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#if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
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/*
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* percpu offsets are zero-based on SMP. PERCPU_VADDR() changes the
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* output PHDR, so the next output section - .init.text - should
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* start another segment - init.
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*/
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PERCPU_VADDR(INTERNODE_CACHE_BYTES, 0, :percpu)
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ASSERT(SIZEOF(.data..percpu) < CONFIG_PHYSICAL_START,
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"per-CPU data too large - increase CONFIG_PHYSICAL_START")
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#endif
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INIT_TEXT_SECTION(PAGE_SIZE)
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#ifdef CONFIG_X86_64
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:init
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#endif
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/*
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* Section for code used exclusively before alternatives are run. All
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* references to such code must be patched out by alternatives, normally
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* by using X86_FEATURE_ALWAYS CPU feature bit.
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*
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* See static_cpu_has() for an example.
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*/
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.altinstr_aux : AT(ADDR(.altinstr_aux) - LOAD_OFFSET) {
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*(.altinstr_aux)
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}
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INIT_DATA_SECTION(16)
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.x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) {
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__x86_cpu_dev_start = .;
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*(.x86_cpu_dev.init)
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__x86_cpu_dev_end = .;
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}
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#ifdef CONFIG_X86_INTEL_MID
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.x86_intel_mid_dev.init : AT(ADDR(.x86_intel_mid_dev.init) - \
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LOAD_OFFSET) {
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__x86_intel_mid_dev_start = .;
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*(.x86_intel_mid_dev.init)
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__x86_intel_mid_dev_end = .;
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}
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#endif
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/*
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* start address and size of operations which during runtime
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* can be patched with virtualization friendly instructions or
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* baremetal native ones. Think page table operations.
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* Details in paravirt_types.h
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*/
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. = ALIGN(8);
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.parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
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__parainstructions = .;
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*(.parainstructions)
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__parainstructions_end = .;
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}
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/*
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* struct alt_inst entries. From the header (alternative.h):
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* "Alternative instructions for different CPU types or capabilities"
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* Think locking instructions on spinlocks.
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*/
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. = ALIGN(8);
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.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
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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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/*
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* And here are the replacement instructions. The linker sticks
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* them as binary blobs. The .altinstructions has enough data to
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* get the address and the length of them to patch the kernel safely.
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*/
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.altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
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*(.altinstr_replacement)
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}
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/*
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* struct iommu_table_entry entries are injected in this section.
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* It is an array of IOMMUs which during run time gets sorted depending
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* on its dependency order. After rootfs_initcall is complete
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* this section can be safely removed.
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*/
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.iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) {
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__iommu_table = .;
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*(.iommu_table)
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__iommu_table_end = .;
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}
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. = ALIGN(8);
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.apicdrivers : AT(ADDR(.apicdrivers) - LOAD_OFFSET) {
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__apicdrivers = .;
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*(.apicdrivers);
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__apicdrivers_end = .;
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}
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. = ALIGN(8);
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/*
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* .exit.text is discard at runtime, not link time, to deal with
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* references from .altinstructions and .eh_frame
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*/
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.exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
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EXIT_TEXT
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}
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.exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) {
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EXIT_DATA
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}
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#if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP)
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PERCPU_SECTION(INTERNODE_CACHE_BYTES)
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#endif
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. = ALIGN(PAGE_SIZE);
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/* freed after init ends here */
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.init.end : AT(ADDR(.init.end) - LOAD_OFFSET) {
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__init_end = .;
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}
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/*
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* smp_locks might be freed after init
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* start/end must be page aligned
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*/
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. = ALIGN(PAGE_SIZE);
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.smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
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__smp_locks = .;
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*(.smp_locks)
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. = ALIGN(PAGE_SIZE);
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__smp_locks_end = .;
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}
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#ifdef CONFIG_X86_64
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.data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
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NOSAVE_DATA
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}
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#endif
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/* BSS */
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. = ALIGN(PAGE_SIZE);
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.bss : AT(ADDR(.bss) - LOAD_OFFSET) {
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__bss_start = .;
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*(.bss..page_aligned)
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*(.bss)
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. = ALIGN(PAGE_SIZE);
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__bss_stop = .;
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}
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. = ALIGN(PAGE_SIZE);
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.brk : AT(ADDR(.brk) - LOAD_OFFSET) {
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__brk_base = .;
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. += 64 * 1024; /* 64k alignment slop space */
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*(.brk_reservation) /* areas brk users have reserved */
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__brk_limit = .;
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}
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. = ALIGN(PAGE_SIZE); /* keep VO_INIT_SIZE page aligned */
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_end = .;
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STABS_DEBUG
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DWARF_DEBUG
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/* Sections to be discarded */
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DISCARDS
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/DISCARD/ : {
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*(.eh_frame)
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}
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}
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#ifdef CONFIG_X86_32
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/*
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* The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
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*/
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. = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
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"kernel image bigger than KERNEL_IMAGE_SIZE");
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#else
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/*
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* Per-cpu symbols which need to be offset from __per_cpu_load
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* for the boot processor.
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*/
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#define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load
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INIT_PER_CPU(gdt_page);
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INIT_PER_CPU(irq_stack_union);
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/*
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* Build-time check on the image size:
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*/
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. = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
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"kernel image bigger than KERNEL_IMAGE_SIZE");
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#ifdef CONFIG_SMP
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. = ASSERT((irq_stack_union == 0),
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"irq_stack_union is not at start of per-cpu area");
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#endif
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#endif /* CONFIG_X86_32 */
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#ifdef CONFIG_KEXEC_CORE
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#include <asm/kexec.h>
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. = ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
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"kexec control code size is too big");
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#endif
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