summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/head64.c
blob: 9ba79543d9ee9f1ee19bce38955467afa04b125f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
/*
 *  prepare to run common code
 *
 *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
 */

#define DISABLE_BRANCH_PROFILING
#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/percpu.h>
#include <linux/start_kernel.h>
#include <linux/io.h>
#include <linux/memblock.h>

#include <asm/processor.h>
#include <asm/proto.h>
#include <asm/smp.h>
#include <asm/setup.h>
#include <asm/desc.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/kdebug.h>
#include <asm/e820/api.h>
#include <asm/bios_ebda.h>
#include <asm/bootparam_utils.h>
#include <asm/microcode.h>
#include <asm/kasan.h>

/*
 * Manage page tables very early on.
 */
extern pgd_t early_top_pgt[PTRS_PER_PGD];
extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
static unsigned int __initdata next_early_pgt;
pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);

#define __head	__section(.head.text)

static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
{
	return ptr - (void *)_text + (void *)physaddr;
}

void __head __startup_64(unsigned long physaddr)
{
	unsigned long load_delta, *p;
	pgdval_t *pgd;
	p4dval_t *p4d;
	pudval_t *pud;
	pmdval_t *pmd, pmd_entry;
	int i;
	unsigned int *next_pgt_ptr;

	/* Is the address too large? */
	if (physaddr >> MAX_PHYSMEM_BITS)
		for (;;);

	/*
	 * Compute the delta between the address I am compiled to run at
	 * and the address I am actually running at.
	 */
	load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map);

	/* Is the address not 2M aligned? */
	if (load_delta & ~PMD_PAGE_MASK)
		for (;;);

	/* Fixup the physical addresses in the page table */

	pgd = fixup_pointer(&early_top_pgt, physaddr);
	pgd[pgd_index(__START_KERNEL_map)] += load_delta;

	if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
		p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
		p4d[511] += load_delta;
	}

	pud = fixup_pointer(&level3_kernel_pgt, physaddr);
	pud[510] += load_delta;
	pud[511] += load_delta;

	pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
	pmd[506] += load_delta;

	/*
	 * Set up the identity mapping for the switchover.  These
	 * entries should *NOT* have the global bit set!  This also
	 * creates a bunch of nonsense entries but that is fine --
	 * it avoids problems around wraparound.
	 */
	next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
	pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
	pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);

	if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
		p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);

		i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
		pgd[i + 0] = (pgdval_t)p4d + _KERNPG_TABLE;
		pgd[i + 1] = (pgdval_t)p4d + _KERNPG_TABLE;

		i = (physaddr >> P4D_SHIFT) % PTRS_PER_P4D;
		p4d[i + 0] = (pgdval_t)pud + _KERNPG_TABLE;
		p4d[i + 1] = (pgdval_t)pud + _KERNPG_TABLE;
	} else {
		i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
		pgd[i + 0] = (pgdval_t)pud + _KERNPG_TABLE;
		pgd[i + 1] = (pgdval_t)pud + _KERNPG_TABLE;
	}

	i = (physaddr >> PUD_SHIFT) % PTRS_PER_PUD;
	pud[i + 0] = (pudval_t)pmd + _KERNPG_TABLE;
	pud[i + 1] = (pudval_t)pmd + _KERNPG_TABLE;

	pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
	pmd_entry +=  physaddr;

	for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
		int idx = i + (physaddr >> PMD_SHIFT) % PTRS_PER_PMD;
		pmd[idx] = pmd_entry + i * PMD_SIZE;
	}

	/*
	 * Fixup the kernel text+data virtual addresses. Note that
	 * we might write invalid pmds, when the kernel is relocated
	 * cleanup_highmap() fixes this up along with the mappings
	 * beyond _end.
	 */

	pmd = fixup_pointer(level2_kernel_pgt, physaddr);
	for (i = 0; i < PTRS_PER_PMD; i++) {
		if (pmd[i] & _PAGE_PRESENT)
			pmd[i] += load_delta;
	}

	/* Fixup phys_base */
	p = fixup_pointer(&phys_base, physaddr);
	*p += load_delta;
}

/* Wipe all early page tables except for the kernel symbol map */
static void __init reset_early_page_tables(void)
{
	memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
	next_early_pgt = 0;
	write_cr3(__pa_nodebug(early_top_pgt));
}

/* Create a new PMD entry */
int __init early_make_pgtable(unsigned long address)
{
	unsigned long physaddr = address - __PAGE_OFFSET;
	pgdval_t pgd, *pgd_p;
	p4dval_t p4d, *p4d_p;
	pudval_t pud, *pud_p;
	pmdval_t pmd, *pmd_p;

	/* Invalid address or early pgt is done ?  */
	if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
		return -1;

again:
	pgd_p = &early_top_pgt[pgd_index(address)].pgd;
	pgd = *pgd_p;

	/*
	 * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
	 * critical -- __PAGE_OFFSET would point us back into the dynamic
	 * range and we might end up looping forever...
	 */
	if (!IS_ENABLED(CONFIG_X86_5LEVEL))
		p4d_p = pgd_p;
	else if (pgd)
		p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
	else {
		if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
			reset_early_page_tables();
			goto again;
		}

		p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
		memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
		*pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
	}
	p4d_p += p4d_index(address);
	p4d = *p4d_p;

	if (p4d)
		pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
	else {
		if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
			reset_early_page_tables();
			goto again;
		}

		pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
		memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
		*p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
	}
	pud_p += pud_index(address);
	pud = *pud_p;

	if (pud)
		pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
	else {
		if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
			reset_early_page_tables();
			goto again;
		}

		pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
		memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
		*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
	}
	pmd = (physaddr & PMD_MASK) + early_pmd_flags;
	pmd_p[pmd_index(address)] = pmd;

	return 0;
}

/* Don't add a printk in there. printk relies on the PDA which is not initialized 
   yet. */
static void __init clear_bss(void)
{
	memset(__bss_start, 0,
	       (unsigned long) __bss_stop - (unsigned long) __bss_start);
}

static unsigned long get_cmd_line_ptr(void)
{
	unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;

	cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;

	return cmd_line_ptr;
}

static void __init copy_bootdata(char *real_mode_data)
{
	char * command_line;
	unsigned long cmd_line_ptr;

	memcpy(&boot_params, real_mode_data, sizeof boot_params);
	sanitize_boot_params(&boot_params);
	cmd_line_ptr = get_cmd_line_ptr();
	if (cmd_line_ptr) {
		command_line = __va(cmd_line_ptr);
		memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
	}
}

asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
{
	int i;

	/*
	 * Build-time sanity checks on the kernel image and module
	 * area mappings. (these are purely build-time and produce no code)
	 */
	BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
	BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
	BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
	BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
	BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
	BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
	BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
				(__START_KERNEL & PGDIR_MASK)));
	BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);

	cr4_init_shadow();

	/* Kill off the identity-map trampoline */
	reset_early_page_tables();

	clear_bss();

	clear_page(init_top_pgt);

	kasan_early_init();

	for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)
		set_intr_gate(i, early_idt_handler_array[i]);
	load_idt((const struct desc_ptr *)&idt_descr);

	copy_bootdata(__va(real_mode_data));

	/*
	 * Load microcode early on BSP.
	 */
	load_ucode_bsp();

	/* set init_top_pgt kernel high mapping*/
	init_top_pgt[511] = early_top_pgt[511];

	x86_64_start_reservations(real_mode_data);
}

void __init x86_64_start_reservations(char *real_mode_data)
{
	/* version is always not zero if it is copied */
	if (!boot_params.hdr.version)
		copy_bootdata(__va(real_mode_data));

	x86_early_init_platform_quirks();

	switch (boot_params.hdr.hardware_subarch) {
	case X86_SUBARCH_INTEL_MID:
		x86_intel_mid_early_setup();
		break;
	default:
		break;
	}

	start_kernel();
}