vmlinux.lds.S 8.9 KB

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  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. #ifdef CONFIG_X86_32
  17. #define LOAD_OFFSET __PAGE_OFFSET
  18. #else
  19. #define LOAD_OFFSET __START_KERNEL_map
  20. #endif
  21. #include <asm-generic/vmlinux.lds.h>
  22. #include <asm/asm-offsets.h>
  23. #include <asm/thread_info.h>
  24. #include <asm/page_types.h>
  25. #include <asm/cache.h>
  26. #include <asm/boot.h>
  27. #undef i386 /* in case the preprocessor is a 32bit one */
  28. OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT)
  29. #ifdef CONFIG_X86_32
  30. OUTPUT_ARCH(i386)
  31. ENTRY(phys_startup_32)
  32. jiffies = jiffies_64;
  33. #else
  34. OUTPUT_ARCH(i386:x86-64)
  35. ENTRY(phys_startup_64)
  36. jiffies_64 = jiffies;
  37. #endif
  38. #if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
  39. /*
  40. * On 64-bit, align RODATA to 2MB so that even with CONFIG_DEBUG_RODATA
  41. * we retain large page mappings for boundaries spanning kernel text, rodata
  42. * and data sections.
  43. *
  44. * However, kernel identity mappings will have different RWX permissions
  45. * to the pages mapping to text and to the pages padding (which are freed) the
  46. * text section. Hence kernel identity mappings will be broken to smaller
  47. * pages. For 64-bit, kernel text and kernel identity mappings are different,
  48. * so we can enable protection checks that come with CONFIG_DEBUG_RODATA,
  49. * as well as retain 2MB large page mappings for kernel text.
  50. */
  51. #define X64_ALIGN_DEBUG_RODATA_BEGIN . = ALIGN(HPAGE_SIZE);
  52. #define X64_ALIGN_DEBUG_RODATA_END \
  53. . = ALIGN(HPAGE_SIZE); \
  54. __end_rodata_hpage_align = .;
  55. #else
  56. #define X64_ALIGN_DEBUG_RODATA_BEGIN
  57. #define X64_ALIGN_DEBUG_RODATA_END
  58. #endif
  59. PHDRS {
  60. text PT_LOAD FLAGS(5); /* R_E */
  61. data PT_LOAD FLAGS(6); /* RW_ */
  62. #ifdef CONFIG_X86_64
  63. #ifdef CONFIG_SMP
  64. percpu PT_LOAD FLAGS(6); /* RW_ */
  65. #endif
  66. init PT_LOAD FLAGS(7); /* RWE */
  67. #endif
  68. note PT_NOTE FLAGS(0); /* ___ */
  69. }
  70. SECTIONS
  71. {
  72. #ifdef CONFIG_X86_32
  73. . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;
  74. phys_startup_32 = startup_32 - LOAD_OFFSET;
  75. #else
  76. . = __START_KERNEL;
  77. phys_startup_64 = startup_64 - LOAD_OFFSET;
  78. #endif
  79. /* Text and read-only data */
  80. .text : AT(ADDR(.text) - LOAD_OFFSET) {
  81. _text = .;
  82. /* bootstrapping code */
  83. HEAD_TEXT
  84. #ifdef CONFIG_X86_32
  85. . = ALIGN(PAGE_SIZE);
  86. *(.text..page_aligned)
  87. #endif
  88. . = ALIGN(8);
  89. _stext = .;
  90. TEXT_TEXT
  91. SCHED_TEXT
  92. LOCK_TEXT
  93. KPROBES_TEXT
  94. ENTRY_TEXT
  95. IRQENTRY_TEXT
  96. *(.fixup)
  97. *(.gnu.warning)
  98. /* End of text section */
  99. _etext = .;
  100. } :text = 0x9090
  101. NOTES :text :note
  102. EXCEPTION_TABLE(16) :text = 0x9090
  103. #if defined(CONFIG_DEBUG_RODATA)
  104. /* .text should occupy whole number of pages */
  105. . = ALIGN(PAGE_SIZE);
  106. #endif
  107. X64_ALIGN_DEBUG_RODATA_BEGIN
  108. RO_DATA(PAGE_SIZE)
  109. X64_ALIGN_DEBUG_RODATA_END
  110. /* Data */
  111. .data : AT(ADDR(.data) - LOAD_OFFSET) {
  112. /* Start of data section */
  113. _sdata = .;
  114. /* init_task */
  115. INIT_TASK_DATA(THREAD_SIZE)
  116. #ifdef CONFIG_X86_32
  117. /* 32 bit has nosave before _edata */
  118. NOSAVE_DATA
  119. #endif
  120. PAGE_ALIGNED_DATA(PAGE_SIZE)
  121. CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES)
  122. DATA_DATA
  123. CONSTRUCTORS
  124. /* rarely changed data like cpu maps */
  125. READ_MOSTLY_DATA(INTERNODE_CACHE_BYTES)
  126. /* End of data section */
  127. _edata = .;
  128. } :data
  129. #ifdef CONFIG_X86_64
  130. . = ALIGN(PAGE_SIZE);
  131. __vvar_page = .;
  132. .vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
  133. /* work around gold bug 13023 */
  134. __vvar_beginning_hack = .;
  135. /* Place all vvars at the offsets in asm/vvar.h. */
  136. #define EMIT_VVAR(name, offset) \
  137. . = __vvar_beginning_hack + offset; \
  138. *(.vvar_ ## name)
  139. #define __VVAR_KERNEL_LDS
  140. #include <asm/vvar.h>
  141. #undef __VVAR_KERNEL_LDS
  142. #undef EMIT_VVAR
  143. } :data
  144. . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
  145. #endif /* CONFIG_X86_64 */
  146. /* Init code and data - will be freed after init */
  147. . = ALIGN(PAGE_SIZE);
  148. .init.begin : AT(ADDR(.init.begin) - LOAD_OFFSET) {
  149. __init_begin = .; /* paired with __init_end */
  150. }
  151. #if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
  152. /*
  153. * percpu offsets are zero-based on SMP. PERCPU_VADDR() changes the
  154. * output PHDR, so the next output section - .init.text - should
  155. * start another segment - init.
  156. */
  157. PERCPU_VADDR(INTERNODE_CACHE_BYTES, 0, :percpu)
  158. #endif
  159. INIT_TEXT_SECTION(PAGE_SIZE)
  160. #ifdef CONFIG_X86_64
  161. :init
  162. #endif
  163. INIT_DATA_SECTION(16)
  164. /*
  165. * Code and data for a variety of lowlevel trampolines, to be
  166. * copied into base memory (< 1 MiB) during initialization.
  167. * Since it is copied early, the main copy can be discarded
  168. * afterwards.
  169. */
  170. .x86_trampoline : AT(ADDR(.x86_trampoline) - LOAD_OFFSET) {
  171. x86_trampoline_start = .;
  172. *(.x86_trampoline)
  173. x86_trampoline_end = .;
  174. }
  175. .x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) {
  176. __x86_cpu_dev_start = .;
  177. *(.x86_cpu_dev.init)
  178. __x86_cpu_dev_end = .;
  179. }
  180. /*
  181. * start address and size of operations which during runtime
  182. * can be patched with virtualization friendly instructions or
  183. * baremetal native ones. Think page table operations.
  184. * Details in paravirt_types.h
  185. */
  186. . = ALIGN(8);
  187. .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
  188. __parainstructions = .;
  189. *(.parainstructions)
  190. __parainstructions_end = .;
  191. }
  192. /*
  193. * struct alt_inst entries. From the header (alternative.h):
  194. * "Alternative instructions for different CPU types or capabilities"
  195. * Think locking instructions on spinlocks.
  196. */
  197. . = ALIGN(8);
  198. .altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
  199. __alt_instructions = .;
  200. *(.altinstructions)
  201. __alt_instructions_end = .;
  202. }
  203. /*
  204. * And here are the replacement instructions. The linker sticks
  205. * them as binary blobs. The .altinstructions has enough data to
  206. * get the address and the length of them to patch the kernel safely.
  207. */
  208. .altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
  209. *(.altinstr_replacement)
  210. }
  211. /*
  212. * struct iommu_table_entry entries are injected in this section.
  213. * It is an array of IOMMUs which during run time gets sorted depending
  214. * on its dependency order. After rootfs_initcall is complete
  215. * this section can be safely removed.
  216. */
  217. .iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) {
  218. __iommu_table = .;
  219. *(.iommu_table)
  220. __iommu_table_end = .;
  221. }
  222. . = ALIGN(8);
  223. .apicdrivers : AT(ADDR(.apicdrivers) - LOAD_OFFSET) {
  224. __apicdrivers = .;
  225. *(.apicdrivers);
  226. __apicdrivers_end = .;
  227. }
  228. . = ALIGN(8);
  229. /*
  230. * .exit.text is discard at runtime, not link time, to deal with
  231. * references from .altinstructions and .eh_frame
  232. */
  233. .exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
  234. EXIT_TEXT
  235. }
  236. .exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) {
  237. EXIT_DATA
  238. }
  239. #if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP)
  240. PERCPU_SECTION(INTERNODE_CACHE_BYTES)
  241. #endif
  242. . = ALIGN(PAGE_SIZE);
  243. /* freed after init ends here */
  244. .init.end : AT(ADDR(.init.end) - LOAD_OFFSET) {
  245. __init_end = .;
  246. }
  247. /*
  248. * smp_locks might be freed after init
  249. * start/end must be page aligned
  250. */
  251. . = ALIGN(PAGE_SIZE);
  252. .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
  253. __smp_locks = .;
  254. *(.smp_locks)
  255. . = ALIGN(PAGE_SIZE);
  256. __smp_locks_end = .;
  257. }
  258. #ifdef CONFIG_X86_64
  259. .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
  260. NOSAVE_DATA
  261. }
  262. #endif
  263. /* BSS */
  264. . = ALIGN(PAGE_SIZE);
  265. .bss : AT(ADDR(.bss) - LOAD_OFFSET) {
  266. __bss_start = .;
  267. *(.bss..page_aligned)
  268. *(.bss)
  269. . = ALIGN(PAGE_SIZE);
  270. __bss_stop = .;
  271. }
  272. . = ALIGN(PAGE_SIZE);
  273. .brk : AT(ADDR(.brk) - LOAD_OFFSET) {
  274. __brk_base = .;
  275. . += 64 * 1024; /* 64k alignment slop space */
  276. *(.brk_reservation) /* areas brk users have reserved */
  277. __brk_limit = .;
  278. }
  279. _end = .;
  280. STABS_DEBUG
  281. DWARF_DEBUG
  282. /* Sections to be discarded */
  283. DISCARDS
  284. /DISCARD/ : { *(.eh_frame) }
  285. }
  286. #ifdef CONFIG_X86_32
  287. /*
  288. * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
  289. */
  290. . = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
  291. "kernel image bigger than KERNEL_IMAGE_SIZE");
  292. #else
  293. /*
  294. * Per-cpu symbols which need to be offset from __per_cpu_load
  295. * for the boot processor.
  296. */
  297. #define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load
  298. INIT_PER_CPU(gdt_page);
  299. INIT_PER_CPU(irq_stack_union);
  300. /*
  301. * Build-time check on the image size:
  302. */
  303. . = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
  304. "kernel image bigger than KERNEL_IMAGE_SIZE");
  305. #ifdef CONFIG_SMP
  306. . = ASSERT((irq_stack_union == 0),
  307. "irq_stack_union is not at start of per-cpu area");
  308. #endif
  309. #endif /* CONFIG_X86_32 */
  310. #ifdef CONFIG_KEXEC
  311. #include <asm/kexec.h>
  312. . = ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
  313. "kexec control code size is too big");
  314. #endif