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
  32 OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT)
  33
  34 #ifdef CONFIG_X86_32
  35 OUTPUT_ARCH(i386)
  36 ENTRY(phys_startup_32)
  37 jiffies = jiffies_64;
  38 #else
  39 OUTPUT_ARCH(i386:x86-64)
  40 ENTRY(phys_startup_64)
  41 jiffies_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
  70 PHDRS {
  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
  82 SECTIONS
  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 #ifdef CONFIG_X86_32
  98                 . = ALIGN(PAGE_SIZE);
  99                 *(.text..page_aligned)
 100 #endif
 101                 . = ALIGN(8);
 102                 _stext = .;
 103                 TEXT_TEXT
 104                 SCHED_TEXT
 105                 LOCK_TEXT
 106                 KPROBES_TEXT
 107                 ENTRY_TEXT
 108                 IRQENTRY_TEXT
 109                 *(.fixup)
 110                 *(.gnu.warning)
 111                 /* End of text section */
 112                 _etext = .;
 113         } :text = 0x9090
 114
 115         NOTES :text :note
 116
 117         EXCEPTION_TABLE(16) :text = 0x9090
 118
 119 #if defined(CONFIG_DEBUG_RODATA)
 120         /* .text should occupy whole number of pages */
 121         . = ALIGN(PAGE_SIZE);
 122 #endif
 123         X64_ALIGN_DEBUG_RODATA_BEGIN
 124         RO_DATA(PAGE_SIZE)
 125         X64_ALIGN_DEBUG_RODATA_END
 126
 127         /* Data */
 128         .data : AT(ADDR(.data) - LOAD_OFFSET) {
 129                 /* Start of data section */
 130                 _sdata = .;
 131
 132                 /* init_task */
 133                 INIT_TASK_DATA(THREAD_SIZE)
 134
 135 #ifdef CONFIG_X86_32
 136                 /* 32 bit has nosave before _edata */
 137                 NOSAVE_DATA
 138 #endif
 139
 140                 PAGE_ALIGNED_DATA(PAGE_SIZE)
 141
 142                 CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES)
 143
 144                 DATA_DATA
 145                 CONSTRUCTORS
 146
 147                 /* rarely changed data like cpu maps */
 148                 READ_MOSTLY_DATA(INTERNODE_CACHE_BYTES)
 149
 150                 /* End of data section */
 151                 _edata = .;
 152         } :data
 153
 154 #ifdef CONFIG_X86_64
 155
 156         . = ALIGN(PAGE_SIZE);
 157         __vvar_page = .;
 158
 159         .vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
 160                 /* work around gold bug 13023 */
 161                 __vvar_beginning_hack = .;
 162
 163                 /* Place all vvars at the offsets in asm/vvar.h. */
 164 #define EMIT_VVAR(name, offset)                         \
 165                 . = __vvar_beginning_hack + offset;     \
 166                 *(.vvar_ ## name)
 167 #define __VVAR_KERNEL_LDS
 168 #include <asm/vvar.h>
 169 #undef __VVAR_KERNEL_LDS
 170 #undef EMIT_VVAR
 171
 172         } :data
 173
 174        . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
 175
 176 #endif /* CONFIG_X86_64 */
 177
 178         /* Init code and data - will be freed after init */
 179         . = ALIGN(PAGE_SIZE);
 180         .init.begin : AT(ADDR(.init.begin) - LOAD_OFFSET) {
 181                 __init_begin = .; /* paired with __init_end */
 182         }
 183
 184 #if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
 185         /*
 186          * percpu offsets are zero-based on SMP.  PERCPU_VADDR() changes the
 187          * output PHDR, so the next output section - .init.text - should
 188          * start another segment - init.
 189          */
 190         PERCPU_VADDR(INTERNODE_CACHE_BYTES, 0, :percpu)
 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         /*
 207          * start address and size of operations which during runtime
 208          * can be patched with virtualization friendly instructions or
 209          * baremetal native ones. Think page table operations.
 210          * Details in paravirt_types.h
 211          */
 212         . = ALIGN(8);
 213         .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
 214                 __parainstructions = .;
 215                 *(.parainstructions)
 216                 __parainstructions_end = .;
 217         }
 218
 219         /*
 220          * struct alt_inst entries. From the header (alternative.h):
 221          * "Alternative instructions for different CPU types or capabilities"
 222          * Think locking instructions on spinlocks.
 223          */
 224         . = ALIGN(8);
 225         .altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
 226                 __alt_instructions = .;
 227                 *(.altinstructions)
 228                 __alt_instructions_end = .;
 229         }
 230
 231         /*
 232          * And here are the replacement instructions. The linker sticks
 233          * them as binary blobs. The .altinstructions has enough data to
 234          * get the address and the length of them to patch the kernel safely.
 235          */
 236         .altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
 237                 *(.altinstr_replacement)
 238         }
 239
 240         /*
 241          * struct iommu_table_entry entries are injected in this section.
 242          * It is an array of IOMMUs which during run time gets sorted depending
 243          * on its dependency order. After rootfs_initcall is complete
 244          * this section can be safely removed.
 245          */
 246         .iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) {
 247                 __iommu_table = .;
 248                 *(.iommu_table)
 249                 __iommu_table_end = .;
 250         }
 251
 252         . = ALIGN(8);
 253         .apicdrivers : AT(ADDR(.apicdrivers) - LOAD_OFFSET) {
 254                 __apicdrivers = .;
 255                 *(.apicdrivers);
 256                 __apicdrivers_end = .;
 257         }
 258
 259         . = ALIGN(8);
 260         /*
 261          * .exit.text is discard at runtime, not link time, to deal with
 262          *  references from .altinstructions and .eh_frame
 263          */
 264         .exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
 265                 EXIT_TEXT
 266         }
 267
 268         .exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) {
 269                 EXIT_DATA
 270         }
 271
 272 #if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP)
 273         PERCPU_SECTION(INTERNODE_CACHE_BYTES)
 274 #endif
 275
 276         . = ALIGN(PAGE_SIZE);
 277
 278         /* freed after init ends here */
 279         .init.end : AT(ADDR(.init.end) - LOAD_OFFSET) {
 280                 __init_end = .;
 281         }
 282
 283         /*
 284          * smp_locks might be freed after init
 285          * start/end must be page aligned
 286          */
 287         . = ALIGN(PAGE_SIZE);
 288         .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
 289                 __smp_locks = .;
 290                 *(.smp_locks)
 291                 . = ALIGN(PAGE_SIZE);
 292                 __smp_locks_end = .;
 293         }
 294
 295 #ifdef CONFIG_X86_64
 296         .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
 297                 NOSAVE_DATA
 298         }
 299 #endif
 300
 301         /* BSS */
 302         . = ALIGN(PAGE_SIZE);
 303         .bss : AT(ADDR(.bss) - LOAD_OFFSET) {
 304                 __bss_start = .;
 305                 *(.bss..page_aligned)
 306                 *(.bss)
 307                 . = ALIGN(PAGE_SIZE);
 308                 __bss_stop = .;
 309         }
 310
 311         . = ALIGN(PAGE_SIZE);
 312         .brk : AT(ADDR(.brk) - LOAD_OFFSET) {
 313                 __brk_base = .;
 314                 . += 64 * 1024;         /* 64k alignment slop space */
 315                 *(.brk_reservation)     /* areas brk users have reserved */
 316                 __brk_limit = .;
 317         }
 318
 319         _end = .;
 320
 321         STABS_DEBUG
 322         DWARF_DEBUG
 323
 324         /* Sections to be discarded */
 325         DISCARDS
 326         /DISCARD/ : { *(.eh_frame) }
 327 }
 328
 329
 330 #ifdef CONFIG_X86_32
 331 /*
 332  * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
 333  */
 334 . = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
 335            "kernel image bigger than KERNEL_IMAGE_SIZE");
 336 #else
 337 /*
 338  * Per-cpu symbols which need to be offset from __per_cpu_load
 339  * for the boot processor.
 340  */
 341 #define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load
 342 INIT_PER_CPU(gdt_page);
 343 INIT_PER_CPU(irq_stack_union);
 344
 345 /*
 346  * Build-time check on the image size:
 347  */
 348 . = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
 349            "kernel image bigger than KERNEL_IMAGE_SIZE");
 350
 351 #ifdef CONFIG_SMP
 352 . = ASSERT((irq_stack_union == 0),
 353            "irq_stack_union is not at start of per-cpu area");
 354 #endif
 355
 356 #endif /* CONFIG_X86_32 */
 357
 358 #ifdef CONFIG_KEXEC
 359 #include <asm/kexec.h>
 360
 361 . = ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
 362            "kexec control code size is too big");
 363 #endif
 364