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 user PT_LOAD FLAGS(5); /* R_E */ 75#ifdef CONFIG_SMP 76 percpu PT_LOAD FLAGS(6); /* RW_ */ 77#endif 78 init PT_LOAD FLAGS(7); /* RWE */ 79#endif 80 note PT_NOTE FLAGS(0); /* ___ */ 81} 82 83SECTIONS 84{ 85#ifdef CONFIG_X86_32 86 . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR; 87 phys_startup_32 = startup_32 - LOAD_OFFSET; 88#else 89 . = __START_KERNEL; 90 phys_startup_64 = startup_64 - LOAD_OFFSET; 91#endif 92 93 /* Text and read-only data */ 94 .text : AT(ADDR(.text) - LOAD_OFFSET) { 95 _text = .; 96 /* bootstrapping code */ 97 HEAD_TEXT 98#ifdef CONFIG_X86_32 99 . = ALIGN(PAGE_SIZE); 100 *(.text..page_aligned) 101#endif 102 . = ALIGN(8); 103 _stext = .; 104 TEXT_TEXT 105 SCHED_TEXT 106 LOCK_TEXT 107 KPROBES_TEXT 108 ENTRY_TEXT 109 IRQENTRY_TEXT 110 *(.fixup) 111 *(.gnu.warning) 112 /* End of text section */ 113 _etext = .; 114 } :text = 0x9090 115 116 NOTES :text :note 117 118 EXCEPTION_TABLE(16) :text = 0x9090 119 120#if defined(CONFIG_DEBUG_RODATA) 121 /* .text should occupy whole number of pages */ 122 . = ALIGN(PAGE_SIZE); 123#endif 124 X64_ALIGN_DEBUG_RODATA_BEGIN 125 RO_DATA(PAGE_SIZE) 126 X64_ALIGN_DEBUG_RODATA_END 127 128 /* Data */ 129 .data : AT(ADDR(.data) - LOAD_OFFSET) { 130 /* Start of data section */ 131 _sdata = .; 132 133 /* init_task */ 134 INIT_TASK_DATA(THREAD_SIZE) 135 136#ifdef CONFIG_X86_32 137 /* 32 bit has nosave before _edata */ 138 NOSAVE_DATA 139#endif 140 141 PAGE_ALIGNED_DATA(PAGE_SIZE) 142 143 CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES) 144 145 DATA_DATA 146 CONSTRUCTORS 147 148 /* rarely changed data like cpu maps */ 149 READ_MOSTLY_DATA(INTERNODE_CACHE_BYTES) 150 151 /* End of data section */ 152 _edata = .; 153 } :data 154 155#ifdef CONFIG_X86_64 156 157#define VSYSCALL_ADDR (-10*1024*1024) 158 159#define VLOAD_OFFSET (VSYSCALL_ADDR - __vsyscall_0 + LOAD_OFFSET) 160#define VLOAD(x) (ADDR(x) - VLOAD_OFFSET) 161 162#define VVIRT_OFFSET (VSYSCALL_ADDR - __vsyscall_0) 163#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET) 164 165 . = ALIGN(4096); 166 __vsyscall_0 = .; 167 168 . = VSYSCALL_ADDR; 169 .vsyscall : AT(VLOAD(.vsyscall)) { 170 *(.vsyscall_0) 171 172 . = 1024; 173 *(.vsyscall_1) 174 175 . = 2048; 176 *(.vsyscall_2) 177 178 . = 4096; /* Pad the whole page. */ 179 } :user =0xcc 180 . = ALIGN(__vsyscall_0 + PAGE_SIZE, PAGE_SIZE); 181 182#undef VSYSCALL_ADDR 183#undef VLOAD_OFFSET 184#undef VLOAD 185#undef VVIRT_OFFSET 186#undef VVIRT 187 188 __vvar_page = .; 189 190 .vvar : AT(ADDR(.vvar) - LOAD_OFFSET) { 191 192 /* Place all vvars at the offsets in asm/vvar.h. */ 193#define EMIT_VVAR(name, offset) \ 194 . = offset; \ 195 *(.vvar_ ## name) 196#define __VVAR_KERNEL_LDS 197#include <asm/vvar.h> 198#undef __VVAR_KERNEL_LDS 199#undef EMIT_VVAR 200 201 } :data 202 203 . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE); 204 205#endif /* CONFIG_X86_64 */ 206 207 /* Init code and data - will be freed after init */ 208 . = ALIGN(PAGE_SIZE); 209 .init.begin : AT(ADDR(.init.begin) - LOAD_OFFSET) { 210 __init_begin = .; /* paired with __init_end */ 211 } 212 213#if defined(CONFIG_X86_64) && defined(CONFIG_SMP) 214 /* 215 * percpu offsets are zero-based on SMP. PERCPU_VADDR() changes the 216 * output PHDR, so the next output section - .init.text - should 217 * start another segment - init. 218 */ 219 PERCPU_VADDR(INTERNODE_CACHE_BYTES, 0, :percpu) 220#endif 221 222 INIT_TEXT_SECTION(PAGE_SIZE) 223#ifdef CONFIG_X86_64 224 :init 225#endif 226 227 INIT_DATA_SECTION(16) 228 229 /* 230 * Code and data for a variety of lowlevel trampolines, to be 231 * copied into base memory (< 1 MiB) during initialization. 232 * Since it is copied early, the main copy can be discarded 233 * afterwards. 234 */ 235 .x86_trampoline : AT(ADDR(.x86_trampoline) - LOAD_OFFSET) { 236 x86_trampoline_start = .; 237 *(.x86_trampoline) 238 x86_trampoline_end = .; 239 } 240 241 .x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) { 242 __x86_cpu_dev_start = .; 243 *(.x86_cpu_dev.init) 244 __x86_cpu_dev_end = .; 245 } 246 247 /* 248 * start address and size of operations which during runtime 249 * can be patched with virtualization friendly instructions or 250 * baremetal native ones. Think page table operations. 251 * Details in paravirt_types.h 252 */ 253 . = ALIGN(8); 254 .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) { 255 __parainstructions = .; 256 *(.parainstructions) 257 __parainstructions_end = .; 258 } 259 260 /* 261 * struct alt_inst entries. From the header (alternative.h): 262 * "Alternative instructions for different CPU types or capabilities" 263 * Think locking instructions on spinlocks. 264 */ 265 . = ALIGN(8); 266 .altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) { 267 __alt_instructions = .; 268 *(.altinstructions) 269 __alt_instructions_end = .; 270 } 271 272 /* 273 * And here are the replacement instructions. The linker sticks 274 * them as binary blobs. The .altinstructions has enough data to 275 * get the address and the length of them to patch the kernel safely. 276 */ 277 .altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) { 278 *(.altinstr_replacement) 279 } 280 281 /* 282 * struct iommu_table_entry entries are injected in this section. 283 * It is an array of IOMMUs which during run time gets sorted depending 284 * on its dependency order. After rootfs_initcall is complete 285 * this section can be safely removed. 286 */ 287 .iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) { 288 __iommu_table = .; 289 *(.iommu_table) 290 __iommu_table_end = .; 291 } 292 293 . = ALIGN(8); 294 .apicdrivers : AT(ADDR(.apicdrivers) - LOAD_OFFSET) { 295 __apicdrivers = .; 296 *(.apicdrivers); 297 __apicdrivers_end = .; 298 } 299 300 . = ALIGN(8); 301 /* 302 * .exit.text is discard at runtime, not link time, to deal with 303 * references from .altinstructions and .eh_frame 304 */ 305 .exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) { 306 EXIT_TEXT 307 } 308 309 .exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) { 310 EXIT_DATA 311 } 312 313#if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP) 314 PERCPU_SECTION(INTERNODE_CACHE_BYTES) 315#endif 316 317 . = ALIGN(PAGE_SIZE); 318 319 /* freed after init ends here */ 320 .init.end : AT(ADDR(.init.end) - LOAD_OFFSET) { 321 __init_end = .; 322 } 323 324 /* 325 * smp_locks might be freed after init 326 * start/end must be page aligned 327 */ 328 . = ALIGN(PAGE_SIZE); 329 .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) { 330 __smp_locks = .; 331 *(.smp_locks) 332 . = ALIGN(PAGE_SIZE); 333 __smp_locks_end = .; 334 } 335 336#ifdef CONFIG_X86_64 337 .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) { 338 NOSAVE_DATA 339 } 340#endif 341 342 /* BSS */ 343 . = ALIGN(PAGE_SIZE); 344 .bss : AT(ADDR(.bss) - LOAD_OFFSET) { 345 __bss_start = .; 346 *(.bss..page_aligned) 347 *(.bss) 348 . = ALIGN(PAGE_SIZE); 349 __bss_stop = .; 350 } 351 352 . = ALIGN(PAGE_SIZE); 353 .brk : AT(ADDR(.brk) - LOAD_OFFSET) { 354 __brk_base = .; 355 . += 64 * 1024; /* 64k alignment slop space */ 356 *(.brk_reservation) /* areas brk users have reserved */ 357 __brk_limit = .; 358 } 359 360 _end = .; 361 362 STABS_DEBUG 363 DWARF_DEBUG 364 365 /* Sections to be discarded */ 366 DISCARDS 367 /DISCARD/ : { *(.eh_frame) } 368} 369 370 371#ifdef CONFIG_X86_32 372/* 373 * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility: 374 */ 375. = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE), 376 "kernel image bigger than KERNEL_IMAGE_SIZE"); 377#else 378/* 379 * Per-cpu symbols which need to be offset from __per_cpu_load 380 * for the boot processor. 381 */ 382#define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load 383INIT_PER_CPU(gdt_page); 384INIT_PER_CPU(irq_stack_union); 385 386/* 387 * Build-time check on the image size: 388 */ 389. = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE), 390 "kernel image bigger than KERNEL_IMAGE_SIZE"); 391 392#ifdef CONFIG_SMP 393. = ASSERT((irq_stack_union == 0), 394 "irq_stack_union is not at start of per-cpu area"); 395#endif 396 397#endif /* CONFIG_X86_32 */ 398 399#ifdef CONFIG_KEXEC 400#include <asm/kexec.h> 401 402. = ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE, 403 "kexec control code size is too big"); 404#endif 405 406