xref: /openbmc/linux/arch/x86/kernel/vmlinux.lds.S (revision f35e839a) 
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		. = ALIGN(8);
98		_stext = .;
99		TEXT_TEXT
100		SCHED_TEXT
101		LOCK_TEXT
102		KPROBES_TEXT
103		ENTRY_TEXT
104		IRQENTRY_TEXT
105		*(.fixup)
106		*(.gnu.warning)
107		/* End of text section */
108		_etext = .;
109	} :text = 0x9090
110
111	NOTES :text :note
112
113	EXCEPTION_TABLE(16) :text = 0x9090
114
115#if defined(CONFIG_DEBUG_RODATA)
116	/* .text should occupy whole number of pages */
117	. = ALIGN(PAGE_SIZE);
118#endif
119	X64_ALIGN_DEBUG_RODATA_BEGIN
120	RO_DATA(PAGE_SIZE)
121	X64_ALIGN_DEBUG_RODATA_END
122
123	/* Data */
124	.data : AT(ADDR(.data) - LOAD_OFFSET) {
125		/* Start of data section */
126		_sdata = .;
127
128		/* init_task */
129		INIT_TASK_DATA(THREAD_SIZE)
130
131#ifdef CONFIG_X86_32
132		/* 32 bit has nosave before _edata */
133		NOSAVE_DATA
134#endif
135
136		PAGE_ALIGNED_DATA(PAGE_SIZE)
137
138		CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES)
139
140		DATA_DATA
141		CONSTRUCTORS
142
143		/* rarely changed data like cpu maps */
144		READ_MOSTLY_DATA(INTERNODE_CACHE_BYTES)
145
146		/* End of data section */
147		_edata = .;
148	} :data
149
150#ifdef CONFIG_X86_64
151
152	. = ALIGN(PAGE_SIZE);
153	__vvar_page = .;
154
155	.vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
156		/* work around gold bug 13023 */
157		__vvar_beginning_hack = .;
158
159		/* Place all vvars at the offsets in asm/vvar.h. */
160#define EMIT_VVAR(name, offset) 			\
161		. = __vvar_beginning_hack + offset;	\
162		*(.vvar_ ## name)
163#define __VVAR_KERNEL_LDS
164#include <asm/vvar.h>
165#undef __VVAR_KERNEL_LDS
166#undef EMIT_VVAR
167
168	} :data
169
170       . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
171
172#endif /* CONFIG_X86_64 */
173
174	/* Init code and data - will be freed after init */
175	. = ALIGN(PAGE_SIZE);
176	.init.begin : AT(ADDR(.init.begin) - LOAD_OFFSET) {
177		__init_begin = .; /* paired with __init_end */
178	}
179
180#if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
181	/*
182	 * percpu offsets are zero-based on SMP.  PERCPU_VADDR() changes the
183	 * output PHDR, so the next output section - .init.text - should
184	 * start another segment - init.
185	 */
186	PERCPU_VADDR(INTERNODE_CACHE_BYTES, 0, :percpu)
187#endif
188
189	INIT_TEXT_SECTION(PAGE_SIZE)
190#ifdef CONFIG_X86_64
191	:init
192#endif
193
194	INIT_DATA_SECTION(16)
195
196	.x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) {
197		__x86_cpu_dev_start = .;
198		*(.x86_cpu_dev.init)
199		__x86_cpu_dev_end = .;
200	}
201
202	/*
203	 * start address and size of operations which during runtime
204	 * can be patched with virtualization friendly instructions or
205	 * baremetal native ones. Think page table operations.
206	 * Details in paravirt_types.h
207	 */
208	. = ALIGN(8);
209	.parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
210		__parainstructions = .;
211		*(.parainstructions)
212		__parainstructions_end = .;
213	}
214
215	/*
216	 * struct alt_inst entries. From the header (alternative.h):
217	 * "Alternative instructions for different CPU types or capabilities"
218	 * Think locking instructions on spinlocks.
219	 */
220	. = ALIGN(8);
221	.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
222		__alt_instructions = .;
223		*(.altinstructions)
224		__alt_instructions_end = .;
225	}
226
227	/*
228	 * And here are the replacement instructions. The linker sticks
229	 * them as binary blobs. The .altinstructions has enough data to
230	 * get the address and the length of them to patch the kernel safely.
231	 */
232	.altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
233		*(.altinstr_replacement)
234	}
235
236	/*
237	 * struct iommu_table_entry entries are injected in this section.
238	 * It is an array of IOMMUs which during run time gets sorted depending
239	 * on its dependency order. After rootfs_initcall is complete
240	 * this section can be safely removed.
241	 */
242	.iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) {
243		__iommu_table = .;
244		*(.iommu_table)
245		__iommu_table_end = .;
246	}
247
248	. = ALIGN(8);
249	.apicdrivers : AT(ADDR(.apicdrivers) - LOAD_OFFSET) {
250		__apicdrivers = .;
251		*(.apicdrivers);
252		__apicdrivers_end = .;
253	}
254
255	. = ALIGN(8);
256	/*
257	 * .exit.text is discard at runtime, not link time, to deal with
258	 *  references from .altinstructions and .eh_frame
259	 */
260	.exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
261		EXIT_TEXT
262	}
263
264	.exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) {
265		EXIT_DATA
266	}
267
268#if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP)
269	PERCPU_SECTION(INTERNODE_CACHE_BYTES)
270#endif
271
272	. = ALIGN(PAGE_SIZE);
273
274	/* freed after init ends here */
275	.init.end : AT(ADDR(.init.end) - LOAD_OFFSET) {
276		__init_end = .;
277	}
278
279	/*
280	 * smp_locks might be freed after init
281	 * start/end must be page aligned
282	 */
283	. = ALIGN(PAGE_SIZE);
284	.smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
285		__smp_locks = .;
286		*(.smp_locks)
287		. = ALIGN(PAGE_SIZE);
288		__smp_locks_end = .;
289	}
290
291#ifdef CONFIG_X86_64
292	.data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
293		NOSAVE_DATA
294	}
295#endif
296
297	/* BSS */
298	. = ALIGN(PAGE_SIZE);
299	.bss : AT(ADDR(.bss) - LOAD_OFFSET) {
300		__bss_start = .;
301		*(.bss..page_aligned)
302		*(.bss)
303		. = ALIGN(PAGE_SIZE);
304		__bss_stop = .;
305	}
306
307	. = ALIGN(PAGE_SIZE);
308	.brk : AT(ADDR(.brk) - LOAD_OFFSET) {
309		__brk_base = .;
310		. += 64 * 1024;		/* 64k alignment slop space */
311		*(.brk_reservation)	/* areas brk users have reserved */
312		__brk_limit = .;
313	}
314
315	_end = .;
316
317        STABS_DEBUG
318        DWARF_DEBUG
319
320	/* Sections to be discarded */
321	DISCARDS
322	/DISCARD/ : { *(.eh_frame) }
323}
324
325
326#ifdef CONFIG_X86_32
327/*
328 * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
329 */
330. = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
331	   "kernel image bigger than KERNEL_IMAGE_SIZE");
332#else
333/*
334 * Per-cpu symbols which need to be offset from __per_cpu_load
335 * for the boot processor.
336 */
337#define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load
338INIT_PER_CPU(gdt_page);
339INIT_PER_CPU(irq_stack_union);
340
341/*
342 * Build-time check on the image size:
343 */
344. = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
345	   "kernel image bigger than KERNEL_IMAGE_SIZE");
346
347#ifdef CONFIG_SMP
348. = ASSERT((irq_stack_union == 0),
349           "irq_stack_union is not at start of per-cpu area");
350#endif
351
352#endif /* CONFIG_X86_32 */
353
354#ifdef CONFIG_KEXEC
355#include <asm/kexec.h>
356
357. = ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
358           "kexec control code size is too big");
359#endif
360
361