2 * ld script for the x86 kernel
4 * Historic 32-bit version written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
6 * Modernisation, unification and other changes and fixes:
7 * Copyright (C) 2007-2009 Sam Ravnborg <sam@ravnborg.org>
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.
18 #define LOAD_OFFSET __PAGE_OFFSET
20 #define LOAD_OFFSET __START_KERNEL_map
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/orc_lookup.h>
28 #include <asm/cache.h>
31 #undef i386 /* in case the preprocessor is a 32bit one */
33 OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT)
37 ENTRY(phys_startup_32)
40 OUTPUT_ARCH(i386:x86-64)
41 ENTRY(phys_startup_64)
45 #if defined(CONFIG_X86_64)
47 * On 64-bit, align RODATA to 2MB so we retain large page mappings for
48 * boundaries spanning kernel text, rodata and data sections.
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 as well as retain 2MB large page
55 * mappings for kernel text.
57 #define X64_ALIGN_RODATA_BEGIN . = ALIGN(HPAGE_SIZE);
59 #define X64_ALIGN_RODATA_END \
60 . = ALIGN(HPAGE_SIZE); \
61 __end_rodata_hpage_align = .;
65 #define X64_ALIGN_RODATA_BEGIN
66 #define X64_ALIGN_RODATA_END
71 text PT_LOAD FLAGS(5); /* R_E */
72 data PT_LOAD FLAGS(6); /* RW_ */
75 percpu PT_LOAD FLAGS(6); /* RW_ */
77 init PT_LOAD FLAGS(7); /* RWE */
79 note PT_NOTE FLAGS(0); /* ___ */
85 . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;
86 phys_startup_32 = ABSOLUTE(startup_32 - LOAD_OFFSET);
89 phys_startup_64 = ABSOLUTE(startup_64 - LOAD_OFFSET);
92 /* Text and read-only data */
93 .text : AT(ADDR(.text) - LOAD_OFFSET) {
96 /* bootstrapping code */
109 /* End of text section */
115 EXCEPTION_TABLE(16) :text = 0x9090
117 /* .text should occupy whole number of pages */
118 . = ALIGN(PAGE_SIZE);
119 X64_ALIGN_RODATA_BEGIN
124 .data : AT(ADDR(.data) - LOAD_OFFSET) {
125 /* Start of data section */
129 INIT_TASK_DATA(THREAD_SIZE)
132 /* 32 bit has nosave before _edata */
136 PAGE_ALIGNED_DATA(PAGE_SIZE)
138 CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES)
143 /* rarely changed data like cpu maps */
144 READ_MOSTLY_DATA(INTERNODE_CACHE_BYTES)
146 /* End of data section */
154 . = ALIGN(PAGE_SIZE);
157 .vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
158 /* work around gold bug 13023 */
159 __vvar_beginning_hack = .;
161 /* Place all vvars at the offsets in asm/vvar.h. */
162 #define EMIT_VVAR(name, offset) \
163 . = __vvar_beginning_hack + offset; \
165 #define __VVAR_KERNEL_LDS
166 #include <asm/vvar.h>
167 #undef __VVAR_KERNEL_LDS
171 * Pad the rest of the page with zeros. Otherwise the loader
172 * can leave garbage here.
174 . = __vvar_beginning_hack + PAGE_SIZE;
177 . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
179 /* Init code and data - will be freed after init */
180 . = ALIGN(PAGE_SIZE);
181 .init.begin : AT(ADDR(.init.begin) - LOAD_OFFSET) {
182 __init_begin = .; /* paired with __init_end */
185 #if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
187 * percpu offsets are zero-based on SMP. PERCPU_VADDR() changes the
188 * output PHDR, so the next output section - .init.text - should
189 * start another segment - init.
191 PERCPU_VADDR(INTERNODE_CACHE_BYTES, 0, :percpu)
192 ASSERT(SIZEOF(.data..percpu) < CONFIG_PHYSICAL_START,
193 "per-CPU data too large - increase CONFIG_PHYSICAL_START")
196 INIT_TEXT_SECTION(PAGE_SIZE)
202 * Section for code used exclusively before alternatives are run. All
203 * references to such code must be patched out by alternatives, normally
204 * by using X86_FEATURE_ALWAYS CPU feature bit.
206 * See static_cpu_has() for an example.
208 .altinstr_aux : AT(ADDR(.altinstr_aux) - LOAD_OFFSET) {
212 INIT_DATA_SECTION(16)
214 .x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) {
215 __x86_cpu_dev_start = .;
217 __x86_cpu_dev_end = .;
220 #ifdef CONFIG_X86_INTEL_MID
221 .x86_intel_mid_dev.init : AT(ADDR(.x86_intel_mid_dev.init) - \
223 __x86_intel_mid_dev_start = .;
224 *(.x86_intel_mid_dev.init)
225 __x86_intel_mid_dev_end = .;
230 * start address and size of operations which during runtime
231 * can be patched with virtualization friendly instructions or
232 * baremetal native ones. Think page table operations.
233 * Details in paravirt_types.h
236 .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
237 __parainstructions = .;
239 __parainstructions_end = .;
243 * struct alt_inst entries. From the header (alternative.h):
244 * "Alternative instructions for different CPU types or capabilities"
245 * Think locking instructions on spinlocks.
248 .altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
249 __alt_instructions = .;
251 __alt_instructions_end = .;
255 * And here are the replacement instructions. The linker sticks
256 * them as binary blobs. The .altinstructions has enough data to
257 * get the address and the length of them to patch the kernel safely.
259 .altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
260 *(.altinstr_replacement)
264 * struct iommu_table_entry entries are injected in this section.
265 * It is an array of IOMMUs which during run time gets sorted depending
266 * on its dependency order. After rootfs_initcall is complete
267 * this section can be safely removed.
269 .iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) {
272 __iommu_table_end = .;
276 .apicdrivers : AT(ADDR(.apicdrivers) - LOAD_OFFSET) {
279 __apicdrivers_end = .;
284 * .exit.text is discard at runtime, not link time, to deal with
285 * references from .altinstructions and .eh_frame
287 .exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
291 .exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) {
295 #if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP)
296 PERCPU_SECTION(INTERNODE_CACHE_BYTES)
299 . = ALIGN(PAGE_SIZE);
301 /* freed after init ends here */
302 .init.end : AT(ADDR(.init.end) - LOAD_OFFSET) {
307 * smp_locks might be freed after init
308 * start/end must be page aligned
310 . = ALIGN(PAGE_SIZE);
311 .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
314 . = ALIGN(PAGE_SIZE);
319 .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
325 . = ALIGN(PAGE_SIZE);
326 .bss : AT(ADDR(.bss) - LOAD_OFFSET) {
328 *(.bss..page_aligned)
330 . = ALIGN(PAGE_SIZE);
334 . = ALIGN(PAGE_SIZE);
335 .brk : AT(ADDR(.brk) - LOAD_OFFSET) {
337 . += 64 * 1024; /* 64k alignment slop space */
338 *(.brk_reservation) /* areas brk users have reserved */
342 . = ALIGN(PAGE_SIZE); /* keep VO_INIT_SIZE page aligned */
348 /* Sections to be discarded */
358 * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
360 . = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
361 "kernel image bigger than KERNEL_IMAGE_SIZE");
364 * Per-cpu symbols which need to be offset from __per_cpu_load
365 * for the boot processor.
367 #define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load
368 INIT_PER_CPU(gdt_page);
369 INIT_PER_CPU(irq_stack_union);
372 * Build-time check on the image size:
374 . = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
375 "kernel image bigger than KERNEL_IMAGE_SIZE");
378 . = ASSERT((irq_stack_union == 0),
379 "irq_stack_union is not at start of per-cpu area");
382 #endif /* CONFIG_X86_32 */
384 #ifdef CONFIG_KEXEC_CORE
385 #include <asm/kexec.h>
387 . = ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
388 "kexec control code size is too big");