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#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 /* 201 * Code and data for a variety of lowlevel trampolines, to be 202 * copied into base memory (< 1 MiB) during initialization. 203 * Since it is copied early, the main copy can be discarded 204 * afterwards. 205 */ 206 .x86_trampoline : AT(ADDR(.x86_trampoline) - LOAD_OFFSET) { 207 x86_trampoline_start = .; 208 *(.x86_trampoline) 209 x86_trampoline_end = .; 210 } 211 212 .x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) { 213 __x86_cpu_dev_start = .; 214 *(.x86_cpu_dev.init) 215 __x86_cpu_dev_end = .; 216 } 217 218 /* 219 * start address and size of operations which during runtime 220 * can be patched with virtualization friendly instructions or 221 * baremetal native ones. Think page table operations. 222 * Details in paravirt_types.h 223 */ 224 . = ALIGN(8); 225 .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) { 226 __parainstructions = .; 227 *(.parainstructions) 228 __parainstructions_end = .; 229 } 230 231 /* 232 * struct alt_inst entries. From the header (alternative.h): 233 * "Alternative instructions for different CPU types or capabilities" 234 * Think locking instructions on spinlocks. 235 */ 236 . = ALIGN(8); 237 .altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) { 238 __alt_instructions = .; 239 *(.altinstructions) 240 __alt_instructions_end = .; 241 } 242 243 /* 244 * And here are the replacement instructions. The linker sticks 245 * them as binary blobs. The .altinstructions has enough data to 246 * get the address and the length of them to patch the kernel safely. 247 */ 248 .altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) { 249 *(.altinstr_replacement) 250 } 251 252 /* 253 * struct iommu_table_entry entries are injected in this section. 254 * It is an array of IOMMUs which during run time gets sorted depending 255 * on its dependency order. After rootfs_initcall is complete 256 * this section can be safely removed. 257 */ 258 .iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) { 259 __iommu_table = .; 260 *(.iommu_table) 261 __iommu_table_end = .; 262 } 263 264 . = ALIGN(8); 265 .apicdrivers : AT(ADDR(.apicdrivers) - LOAD_OFFSET) { 266 __apicdrivers = .; 267 *(.apicdrivers); 268 __apicdrivers_end = .; 269 } 270 271 . = ALIGN(8); 272 /* 273 * .exit.text is discard at runtime, not link time, to deal with 274 * references from .altinstructions and .eh_frame 275 */ 276 .exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) { 277 EXIT_TEXT 278 } 279 280 .exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) { 281 EXIT_DATA 282 } 283 284#if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP) 285 PERCPU_SECTION(INTERNODE_CACHE_BYTES) 286#endif 287 288 . = ALIGN(PAGE_SIZE); 289 290 /* freed after init ends here */ 291 .init.end : AT(ADDR(.init.end) - LOAD_OFFSET) { 292 __init_end = .; 293 } 294 295 /* 296 * smp_locks might be freed after init 297 * start/end must be page aligned 298 */ 299 . = ALIGN(PAGE_SIZE); 300 .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) { 301 __smp_locks = .; 302 *(.smp_locks) 303 . = ALIGN(PAGE_SIZE); 304 __smp_locks_end = .; 305 } 306 307#ifdef CONFIG_X86_64 308 .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) { 309 NOSAVE_DATA 310 } 311#endif 312 313 /* BSS */ 314 . = ALIGN(PAGE_SIZE); 315 .bss : AT(ADDR(.bss) - LOAD_OFFSET) { 316 __bss_start = .; 317 *(.bss..page_aligned) 318 *(.bss) 319 . = ALIGN(PAGE_SIZE); 320 __bss_stop = .; 321 } 322 323 . = ALIGN(PAGE_SIZE); 324 .brk : AT(ADDR(.brk) - LOAD_OFFSET) { 325 __brk_base = .; 326 . += 64 * 1024; /* 64k alignment slop space */ 327 *(.brk_reservation) /* areas brk users have reserved */ 328 __brk_limit = .; 329 } 330 331 _end = .; 332 333 STABS_DEBUG 334 DWARF_DEBUG 335 336 /* Sections to be discarded */ 337 DISCARDS 338 /DISCARD/ : { *(.eh_frame) } 339} 340 341 342#ifdef CONFIG_X86_32 343/* 344 * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility: 345 */ 346. = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE), 347 "kernel image bigger than KERNEL_IMAGE_SIZE"); 348#else 349/* 350 * Per-cpu symbols which need to be offset from __per_cpu_load 351 * for the boot processor. 352 */ 353#define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load 354INIT_PER_CPU(gdt_page); 355INIT_PER_CPU(irq_stack_union); 356 357/* 358 * Build-time check on the image size: 359 */ 360. = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE), 361 "kernel image bigger than KERNEL_IMAGE_SIZE"); 362 363#ifdef CONFIG_SMP 364. = ASSERT((irq_stack_union == 0), 365 "irq_stack_union is not at start of per-cpu area"); 366#endif 367 368#endif /* CONFIG_X86_32 */ 369 370#ifdef CONFIG_KEXEC 371#include <asm/kexec.h> 372 373. = ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE, 374 "kexec control code size is too big"); 375#endif 376 377