93dbda7cbc
Impact: new interface Add a brk()-like allocator which effectively extends the bss in order to allow very early code to do dynamic allocations. This is better than using statically allocated arrays for data in subsystems which may never get used. The space for brk allocations is in the bss ELF segment, so that the space is mapped properly by the code which maps the kernel, and so that bootloaders keep the space free rather than putting a ramdisk or something into it. The bss itself, delimited by __bss_stop, ends before the brk area (__brk_base to __brk_limit). The kernel text, data and bss is reserved up to __bss_stop. Any brk-allocated data is reserved separately just before the kernel pagetable is built, as that code allocates from unreserved spaces in the e820 map, potentially allocating from any unused brk memory. Ultimately any unused memory in the brk area is used in the general kernel memory pool. Initially the brk space is set to 1MB, which is probably much larger than any user needs (the largest current user is i386 head_32.S's code to build the pagetables to map the kernel, which can get fairly large with a big kernel image and no PSE support). So long as the system has sufficient memory for the bootloader to reserve the kernel+1MB brk, there are no bad effects resulting from an over-large brk. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
294 lines
7.3 KiB
ArmAsm
294 lines
7.3 KiB
ArmAsm
/* ld script to make x86-64 Linux kernel
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* Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>;
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*/
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#define LOAD_OFFSET __START_KERNEL_map
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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/page_types.h>
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#undef i386 /* in case the preprocessor is a 32bit one */
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OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64", "elf64-x86-64")
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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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PHDRS {
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text PT_LOAD FLAGS(5); /* R_E */
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data PT_LOAD FLAGS(7); /* RWE */
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user PT_LOAD FLAGS(7); /* RWE */
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data.init PT_LOAD FLAGS(7); /* RWE */
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#ifdef CONFIG_SMP
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percpu PT_LOAD FLAGS(7); /* RWE */
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#endif
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data.init2 PT_LOAD FLAGS(7); /* RWE */
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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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. = __START_KERNEL;
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phys_startup_64 = startup_64 - LOAD_OFFSET;
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.text : AT(ADDR(.text) - LOAD_OFFSET) {
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_text = .; /* Text and read-only data */
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/* First the code that has to be first for bootstrapping */
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*(.text.head)
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_stext = .;
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/* Then the rest */
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TEXT_TEXT
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SCHED_TEXT
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LOCK_TEXT
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KPROBES_TEXT
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IRQENTRY_TEXT
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*(.fixup)
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*(.gnu.warning)
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_etext = .; /* End of text section */
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} :text = 0x9090
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NOTES :text :note
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. = ALIGN(16); /* Exception table */
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__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
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__start___ex_table = .;
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*(__ex_table)
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__stop___ex_table = .;
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} :text = 0x9090
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RODATA
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. = ALIGN(PAGE_SIZE); /* Align data segment to page size boundary */
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/* Data */
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.data : AT(ADDR(.data) - LOAD_OFFSET) {
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DATA_DATA
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CONSTRUCTORS
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_edata = .; /* End of data section */
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} :data
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.data.cacheline_aligned : AT(ADDR(.data.cacheline_aligned) - LOAD_OFFSET) {
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. = ALIGN(PAGE_SIZE);
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. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
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*(.data.cacheline_aligned)
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}
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. = ALIGN(CONFIG_X86_INTERNODE_CACHE_BYTES);
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.data.read_mostly : AT(ADDR(.data.read_mostly) - LOAD_OFFSET) {
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*(.data.read_mostly)
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}
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#define VSYSCALL_ADDR (-10*1024*1024)
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#define VSYSCALL_PHYS_ADDR ((LOADADDR(.data.read_mostly) + SIZEOF(.data.read_mostly) + 4095) & ~(4095))
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#define VSYSCALL_VIRT_ADDR ((ADDR(.data.read_mostly) + SIZEOF(.data.read_mostly) + 4095) & ~(4095))
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#define VLOAD_OFFSET (VSYSCALL_ADDR - VSYSCALL_PHYS_ADDR)
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#define VLOAD(x) (ADDR(x) - VLOAD_OFFSET)
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#define VVIRT_OFFSET (VSYSCALL_ADDR - VSYSCALL_VIRT_ADDR)
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#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)
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. = VSYSCALL_ADDR;
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.vsyscall_0 : AT(VSYSCALL_PHYS_ADDR) { *(.vsyscall_0) } :user
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__vsyscall_0 = VSYSCALL_VIRT_ADDR;
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. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
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.vsyscall_fn : AT(VLOAD(.vsyscall_fn)) { *(.vsyscall_fn) }
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. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
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.vsyscall_gtod_data : AT(VLOAD(.vsyscall_gtod_data))
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{ *(.vsyscall_gtod_data) }
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vsyscall_gtod_data = VVIRT(.vsyscall_gtod_data);
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.vsyscall_clock : AT(VLOAD(.vsyscall_clock))
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{ *(.vsyscall_clock) }
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vsyscall_clock = VVIRT(.vsyscall_clock);
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.vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1))
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{ *(.vsyscall_1) }
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.vsyscall_2 ADDR(.vsyscall_0) + 2048: AT(VLOAD(.vsyscall_2))
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{ *(.vsyscall_2) }
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.vgetcpu_mode : AT(VLOAD(.vgetcpu_mode)) { *(.vgetcpu_mode) }
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vgetcpu_mode = VVIRT(.vgetcpu_mode);
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. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
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.jiffies : AT(VLOAD(.jiffies)) { *(.jiffies) }
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jiffies = VVIRT(.jiffies);
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.vsyscall_3 ADDR(.vsyscall_0) + 3072: AT(VLOAD(.vsyscall_3))
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{ *(.vsyscall_3) }
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. = VSYSCALL_VIRT_ADDR + PAGE_SIZE;
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#undef VSYSCALL_ADDR
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#undef VSYSCALL_PHYS_ADDR
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#undef VSYSCALL_VIRT_ADDR
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#undef VLOAD_OFFSET
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#undef VLOAD
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#undef VVIRT_OFFSET
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#undef VVIRT
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.data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) {
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. = ALIGN(THREAD_SIZE); /* init_task */
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*(.data.init_task)
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}:data.init
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.data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) {
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. = ALIGN(PAGE_SIZE);
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*(.data.page_aligned)
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}
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.smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
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/* might get freed after init */
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. = ALIGN(PAGE_SIZE);
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__smp_alt_begin = .;
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__smp_locks = .;
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*(.smp_locks)
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__smp_locks_end = .;
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. = ALIGN(PAGE_SIZE);
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__smp_alt_end = .;
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}
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. = ALIGN(PAGE_SIZE); /* Init code and data */
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__init_begin = .; /* paired with __init_end */
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.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
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_sinittext = .;
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INIT_TEXT
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_einittext = .;
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}
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.init.data : AT(ADDR(.init.data) - LOAD_OFFSET) {
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__initdata_begin = .;
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INIT_DATA
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__initdata_end = .;
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}
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.init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) {
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. = ALIGN(16);
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__setup_start = .;
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*(.init.setup)
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__setup_end = .;
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}
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.initcall.init : AT(ADDR(.initcall.init) - LOAD_OFFSET) {
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__initcall_start = .;
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INITCALLS
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__initcall_end = .;
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}
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.con_initcall.init : AT(ADDR(.con_initcall.init) - LOAD_OFFSET) {
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__con_initcall_start = .;
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*(.con_initcall.init)
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__con_initcall_end = .;
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}
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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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SECURITY_INIT
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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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.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
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. = ALIGN(8);
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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 : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
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*(.altinstr_replacement)
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}
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/* .exit.text is discard at runtime, not link time, to deal with references
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from .altinstructions and .eh_frame */
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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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#ifdef CONFIG_BLK_DEV_INITRD
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. = ALIGN(PAGE_SIZE);
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.init.ramfs : AT(ADDR(.init.ramfs) - LOAD_OFFSET) {
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__initramfs_start = .;
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*(.init.ramfs)
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__initramfs_end = .;
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}
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#endif
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#ifdef 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 - __data_nosave - should
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* start another section data.init2. Also, pda should be at the head of
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* percpu area. Preallocate it and define the percpu offset symbol
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* so that it can be accessed as a percpu variable.
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*/
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. = ALIGN(PAGE_SIZE);
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PERCPU_VADDR(0, :percpu)
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#else
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PERCPU(PAGE_SIZE)
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#endif
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. = ALIGN(PAGE_SIZE);
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__init_end = .;
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.data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
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. = ALIGN(PAGE_SIZE);
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__nosave_begin = .;
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*(.data.nosave)
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. = ALIGN(PAGE_SIZE);
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__nosave_end = .;
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} :data.init2 /* use another section data.init2, see PERCPU_VADDR() above */
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.bss : AT(ADDR(.bss) - LOAD_OFFSET) {
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. = ALIGN(PAGE_SIZE);
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__bss_start = .; /* BSS */
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*(.bss.page_aligned)
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*(.bss)
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__bss_stop = .;
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. = ALIGN(PAGE_SIZE);
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__brk_base = . ;
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. += 1024 * 1024 ;
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__brk_limit = . ;
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}
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_end = . ;
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/* Sections to be discarded */
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/DISCARD/ : {
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*(.exitcall.exit)
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*(.eh_frame)
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}
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STABS_DEBUG
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DWARF_DEBUG
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}
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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 = per_cpu__##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((per_cpu__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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#ifdef CONFIG_KEXEC
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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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