LXR linux/arch/x86/kernel/vmlinux.lds.S

   1/*
   2 * ld script for the x86 kernel
   3 *
   4 * Historic 32-bit version written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
   5 *
   6 * Modernisation, unification and other changes and fixes:
   7 *   Copyright (C) 2007-2009  Sam Ravnborg <sam@ravnborg.org>
   8 *
   9 *
  10 * Don't define absolute symbols until and unless you know that symbol
  11 * value is should remain constant even if kernel image is relocated
  12 * at run time. Absolute symbols are not relocated. If symbol value should
  13 * change if kernel is relocated, make the symbol section relative and
  14 * put it inside the section definition.
  15 */
  16
  17#ifdef CONFIG_X86_32
  18#define LOAD_OFFSET __PAGE_OFFSET
  19#else
  20#define LOAD_OFFSET __START_KERNEL_map
  21#endif
  22
  23#include <asm-generic/vmlinux.lds.h>
  24#include <asm/asm-offsets.h>
  25#include <asm/thread_info.h>
  26#include <asm/page_types.h>
  27#include <asm/cache.h>
  28#include <asm/boot.h>
  29
  30#undef i386     /* in case the preprocessor is a 32bit one */
  31
  32OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT)
  33
  34#ifdef CONFIG_X86_32
  35OUTPUT_ARCH(i386)
  36ENTRY(phys_startup_32)
  37jiffies = jiffies_64;
  38#else
  39OUTPUT_ARCH(i386:x86-64)
  40ENTRY(phys_startup_64)
  41jiffies_64 = jiffies;
  42#endif
  43
  44#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
  45/*
  46 * On 64-bit, align RODATA to 2MB so that even with CONFIG_DEBUG_RODATA
  47 * we retain large page mappings for boundaries spanning kernel text, rodata
  48 * and data sections.
  49 *
  50 * However, kernel identity mappings will have different RWX permissions
  51 * to the pages mapping to text and to the pages padding (which are freed) the
  52 * text section. Hence kernel identity mappings will be broken to smaller
  53 * pages. For 64-bit, kernel text and kernel identity mappings are different,
  54 * so we can enable protection checks that come with CONFIG_DEBUG_RODATA,
  55 * as well as retain 2MB large page mappings for kernel text.
  56 */
  57#define X64_ALIGN_DEBUG_RODATA_BEGIN    . = ALIGN(HPAGE_SIZE);
  58
  59#define X64_ALIGN_DEBUG_RODATA_END                              \
  60                . = ALIGN(HPAGE_SIZE);                          \
  61                __end_rodata_hpage_align = .;
  62
  63#else
  64
  65#define X64_ALIGN_DEBUG_RODATA_BEGIN
  66#define X64_ALIGN_DEBUG_RODATA_END
  67
  68#endif
  69
  70PHDRS {
  71        text PT_LOAD FLAGS(5);          /* R_E */
  72        data PT_LOAD FLAGS(6);          /* RW_ */
  73#ifdef CONFIG_X86_64
  74#ifdef CONFIG_SMP
  75        percpu PT_LOAD FLAGS(6);        /* RW_ */
  76#endif
  77        init PT_LOAD FLAGS(7);          /* RWE */
  78#endif
  79        note PT_NOTE FLAGS(0);          /* ___ */
  80}
  81
  82SECTIONS
  83{
  84#ifdef CONFIG_X86_32
  85        . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;
  86        phys_startup_32 = startup_32 - LOAD_OFFSET;
  87#else
  88        . = __START_KERNEL;
  89        phys_startup_64 = startup_64 - LOAD_OFFSET;
  90#endif
  91
  92        /* Text and read-only data */
  93        .text :  AT(ADDR(.text) - LOAD_OFFSET) {
  94                _text = .;
  95                /* bootstrapping code */
  96                HEAD_TEXT
  97                . = ALIGN(8);
  98                _stext = .;
  99                TEXT_TEXT
 100                SCHED_TEXT
 101                LOCK_TEXT
 102                KPROBES_TEXT
 103                ENTRY_TEXT
 104                IRQENTRY_TEXT
 105                *(.fixup)
 106                *(.gnu.warning)
 107                /* End of text section */
 108                _etext = .;
 109        } :text = 0x9090
 110
 111        NOTES :text :note
 112
 113        EXCEPTION_TABLE(16) :text = 0x9090
 114
 115#if defined(CONFIG_DEBUG_RODATA)
 116        /* .text should occupy whole number of pages */
 117        . = ALIGN(PAGE_SIZE);
 118#endif
 119        X64_ALIGN_DEBUG_RODATA_BEGIN
 120        RO_DATA(PAGE_SIZE)
 121        X64_ALIGN_DEBUG_RODATA_END
 122
 123        /* Data */
 124        .data : AT(ADDR(.data) - LOAD_OFFSET) {
 125                /* Start of data section */
 126                _sdata = .;
 127
 128                /* init_task */
 129                INIT_TASK_DATA(THREAD_SIZE)
 130
 131#ifdef CONFIG_X86_32
 132                /* 32 bit has nosave before _edata */
 133                NOSAVE_DATA
 134#endif
 135
 136                PAGE_ALIGNED_DATA(PAGE_SIZE)
 137
 138                CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES)
 139
 140                DATA_DATA
 141                CONSTRUCTORS
 142
 143                /* rarely changed data like cpu maps */
 144                READ_MOSTLY_DATA(INTERNODE_CACHE_BYTES)
 145
 146                /* End of data section */
 147                _edata = .;
 148        } :data
 149
 150
 151        . = ALIGN(PAGE_SIZE);
 152        __vvar_page = .;
 153
 154        .vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
 155                /* work around gold bug 13023 */
 156                __vvar_beginning_hack = .;
 157
 158                /* Place all vvars at the offsets in asm/vvar.h. */
 159#define EMIT_VVAR(name, offset)                         \
 160                . = __vvar_beginning_hack + offset;     \
 161                *(.vvar_ ## name)
 162#define __VVAR_KERNEL_LDS
 163#include <asm/vvar.h>
 164#undef __VVAR_KERNEL_LDS
 165#undef EMIT_VVAR
 166
 167                /*
 168                 * Pad the rest of the page with zeros.  Otherwise the loader
 169                 * can leave garbage here.
 170                 */
 171                . = __vvar_beginning_hack + PAGE_SIZE;
 172        } :data
 173
 174       . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
 175
 176        /* Init code and data - will be freed after init */
 177        . = ALIGN(PAGE_SIZE);
 178        .init.begin : AT(ADDR(.init.begin) - LOAD_OFFSET) {
 179                __init_begin = .; /* paired with __init_end */
 180        }
 181
 182#if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
 183        /*
 184         * percpu offsets are zero-based on SMP.  PERCPU_VADDR() changes the
 185         * output PHDR, so the next output section - .init.text - should
 186         * start another segment - init.
 187         */
 188        PERCPU_VADDR(INTERNODE_CACHE_BYTES, 0, :percpu)
 189        ASSERT(SIZEOF(.data..percpu) < CONFIG_PHYSICAL_START,
 190               "per-CPU data too large - increase CONFIG_PHYSICAL_START")
 191#endif
 192
 193        INIT_TEXT_SECTION(PAGE_SIZE)
 194#ifdef CONFIG_X86_64
 195        :init
 196#endif
 197
 198        INIT_DATA_SECTION(16)
 199
 200        .x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) {
 201                __x86_cpu_dev_start = .;
 202                *(.x86_cpu_dev.init)
 203                __x86_cpu_dev_end = .;
 204        }
 205
 206#ifdef CONFIG_X86_INTEL_MID
 207        .x86_intel_mid_dev.init : AT(ADDR(.x86_intel_mid_dev.init) - \
 208                                                                LOAD_OFFSET) {
 209                __x86_intel_mid_dev_start = .;
 210                *(.x86_intel_mid_dev.init)
 211                __x86_intel_mid_dev_end = .;
 212        }
 213#endif
 214
 215        /*
 216         * start address and size of operations which during runtime
 217         * can be patched with virtualization friendly instructions or
 218         * baremetal native ones. Think page table operations.
 219         * Details in paravirt_types.h
 220         */
 221        . = ALIGN(8);
 222        .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
 223                __parainstructions = .;
 224                *(.parainstructions)
 225                __parainstructions_end = .;
 226        }
 227
 228        /*
 229         * struct alt_inst entries. From the header (alternative.h):
 230         * "Alternative instructions for different CPU types or capabilities"
 231         * Think locking instructions on spinlocks.
 232         */
 233        . = ALIGN(8);
 234        .altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
 235                __alt_instructions = .;
 236                *(.altinstructions)
 237                __alt_instructions_end = .;
 238        }
 239
 240        /*
 241         * And here are the replacement instructions. The linker sticks
 242         * them as binary blobs. The .altinstructions has enough data to
 243         * get the address and the length of them to patch the kernel safely.
 244         */
 245        .altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
 246                *(.altinstr_replacement)
 247        }
 248
 249        /*
 250         * struct iommu_table_entry entries are injected in this section.
 251         * It is an array of IOMMUs which during run time gets sorted depending
 252         * on its dependency order. After rootfs_initcall is complete
 253         * this section can be safely removed.
 254         */
 255        .iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) {
 256                __iommu_table = .;
 257                *(.iommu_table)
 258                __iommu_table_end = .;
 259        }
 260
 261        . = ALIGN(8);
 262        .apicdrivers : AT(ADDR(.apicdrivers) - LOAD_OFFSET) {
 263                __apicdrivers = .;
 264                *(.apicdrivers);
 265                __apicdrivers_end = .;
 266        }
 267
 268        . = ALIGN(8);
 269        /*
 270         * .exit.text is discard at runtime, not link time, to deal with
 271         *  references from .altinstructions and .eh_frame
 272         */
 273        .exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
 274                EXIT_TEXT
 275        }
 276
 277        .exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) {
 278                EXIT_DATA
 279        }
 280
 281#if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP)
 282        PERCPU_SECTION(INTERNODE_CACHE_BYTES)
 283#endif
 284
 285        . = ALIGN(PAGE_SIZE);
 286
 287        /* freed after init ends here */
 288        .init.end : AT(ADDR(.init.end) - LOAD_OFFSET) {
 289                __init_end = .;
 290        }
 291
 292        /*
 293         * smp_locks might be freed after init
 294         * start/end must be page aligned
 295         */
 296        . = ALIGN(PAGE_SIZE);
 297        .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
 298                __smp_locks = .;
 299                *(.smp_locks)
 300                . = ALIGN(PAGE_SIZE);
 301                __smp_locks_end = .;
 302        }
 303
 304#ifdef CONFIG_X86_64
 305        .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
 306                NOSAVE_DATA
 307        }
 308#endif
 309
 310        /* BSS */
 311        . = ALIGN(PAGE_SIZE);
 312        .bss : AT(ADDR(.bss) - LOAD_OFFSET) {
 313                __bss_start = .;
 314                *(.bss..page_aligned)
 315                *(.bss)
 316                . = ALIGN(PAGE_SIZE);
 317                __bss_stop = .;
 318        }
 319
 320        . = ALIGN(PAGE_SIZE);
 321        .brk : AT(ADDR(.brk) - LOAD_OFFSET) {
 322                __brk_base = .;
 323                . += 64 * 1024;         /* 64k alignment slop space */
 324                *(.brk_reservation)     /* areas brk users have reserved */
 325                __brk_limit = .;
 326        }
 327
 328        _end = .;
 329
 330        STABS_DEBUG
 331        DWARF_DEBUG
 332
 333        /* Sections to be discarded */
 334        DISCARDS
 335        /DISCARD/ : { *(.eh_frame) }
 336}
 337
 338
 339#ifdef CONFIG_X86_32
 340/*
 341 * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
 342 */
 343. = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
 344           "kernel image bigger than KERNEL_IMAGE_SIZE");
 345#else
 346/*
 347 * Per-cpu symbols which need to be offset from __per_cpu_load
 348 * for the boot processor.
 349 */
 350#define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load
 351INIT_PER_CPU(gdt_page);
 352INIT_PER_CPU(irq_stack_union);
 353
 354/*
 355 * Build-time check on the image size:
 356 */
 357. = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
 358           "kernel image bigger than KERNEL_IMAGE_SIZE");
 359
 360#ifdef CONFIG_SMP
 361. = ASSERT((irq_stack_union == 0),
 362           "irq_stack_union is not at start of per-cpu area");
 363#endif
 364
 365#endif /* CONFIG_X86_32 */
 366
 367#ifdef CONFIG_KEXEC_CORE
 368#include <asm/kexec.h>
 369
 370. = ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
 371           "kexec control code size is too big");
 372#endif
 373
 374