1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * prepare to run common code
4 *
5 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
6 */
7
8 /* cpu_feature_enabled() cannot be used this early */
9 #define USE_EARLY_PGTABLE_L5
10
11 #include <linux/init.h>
12 #include <linux/linkage.h>
13 #include <linux/types.h>
14 #include <linux/kernel.h>
15 #include <linux/string.h>
16 #include <linux/percpu.h>
17 #include <linux/start_kernel.h>
18 #include <linux/io.h>
19 #include <linux/memblock.h>
20 #include <linux/cc_platform.h>
21 #include <linux/pgtable.h>
22
23 #include <asm/asm.h>
24 #include <asm/page_64.h>
25 #include <asm/processor.h>
26 #include <asm/proto.h>
27 #include <asm/smp.h>
28 #include <asm/setup.h>
29 #include <asm/desc.h>
30 #include <asm/tlbflush.h>
31 #include <asm/sections.h>
32 #include <asm/kdebug.h>
33 #include <asm/e820/api.h>
34 #include <asm/bios_ebda.h>
35 #include <asm/bootparam_utils.h>
36 #include <asm/microcode.h>
37 #include <asm/kasan.h>
38 #include <asm/fixmap.h>
39 #include <asm/realmode.h>
40 #include <asm/extable.h>
41 #include <asm/trapnr.h>
42 #include <asm/sev.h>
43 #include <asm/tdx.h>
44 #include <asm/init.h>
45
46 /*
47 * Manage page tables very early on.
48 */
49 extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
50 unsigned int __initdata next_early_pgt;
51 SYM_PIC_ALIAS(next_early_pgt);
52 pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
53
54 unsigned int __pgtable_l5_enabled __ro_after_init;
55 unsigned int pgdir_shift __ro_after_init = 39;
56 EXPORT_SYMBOL(pgdir_shift);
57 unsigned int ptrs_per_p4d __ro_after_init = 1;
58 EXPORT_SYMBOL(ptrs_per_p4d);
59
60 unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE_L4;
61 EXPORT_SYMBOL(page_offset_base);
62 unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4;
63 EXPORT_SYMBOL(vmalloc_base);
64 unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
65 EXPORT_SYMBOL(vmemmap_base);
66
67 /* Wipe all early page tables except for the kernel symbol map */
reset_early_page_tables(void)68 static void __init reset_early_page_tables(void)
69 {
70 memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
71 next_early_pgt = 0;
72 write_cr3(__sme_pa_nodebug(early_top_pgt));
73 }
74
75 /* Create a new PMD entry */
__early_make_pgtable(unsigned long address,pmdval_t pmd)76 bool __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
77 {
78 unsigned long physaddr = address - __PAGE_OFFSET;
79 pgdval_t pgd, *pgd_p;
80 p4dval_t p4d, *p4d_p;
81 pudval_t pud, *pud_p;
82 pmdval_t *pmd_p;
83
84 /* Invalid address or early pgt is done ? */
85 if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
86 return false;
87
88 again:
89 pgd_p = &early_top_pgt[pgd_index(address)].pgd;
90 pgd = *pgd_p;
91
92 /*
93 * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
94 * critical -- __PAGE_OFFSET would point us back into the dynamic
95 * range and we might end up looping forever...
96 */
97 if (!pgtable_l5_enabled())
98 p4d_p = pgd_p;
99 else if (pgd)
100 p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
101 else {
102 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
103 reset_early_page_tables();
104 goto again;
105 }
106
107 p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
108 memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
109 *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
110 }
111 p4d_p += p4d_index(address);
112 p4d = *p4d_p;
113
114 if (p4d)
115 pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
116 else {
117 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
118 reset_early_page_tables();
119 goto again;
120 }
121
122 pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
123 memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
124 *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
125 }
126 pud_p += pud_index(address);
127 pud = *pud_p;
128
129 if (pud)
130 pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
131 else {
132 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
133 reset_early_page_tables();
134 goto again;
135 }
136
137 pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
138 memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
139 *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
140 }
141 pmd_p[pmd_index(address)] = pmd;
142
143 return true;
144 }
145
early_make_pgtable(unsigned long address)146 static bool __init early_make_pgtable(unsigned long address)
147 {
148 unsigned long physaddr = address - __PAGE_OFFSET;
149 pmdval_t pmd;
150
151 pmd = (physaddr & PMD_MASK) + early_pmd_flags;
152
153 return __early_make_pgtable(address, pmd);
154 }
155
do_early_exception(struct pt_regs * regs,int trapnr)156 void __init do_early_exception(struct pt_regs *regs, int trapnr)
157 {
158 if (trapnr == X86_TRAP_PF &&
159 early_make_pgtable(native_read_cr2()))
160 return;
161
162 if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT) &&
163 trapnr == X86_TRAP_VC && handle_vc_boot_ghcb(regs))
164 return;
165
166 if (trapnr == X86_TRAP_VE && tdx_early_handle_ve(regs))
167 return;
168
169 early_fixup_exception(regs, trapnr);
170 }
171
172 /* Don't add a printk in there. printk relies on the PDA which is not initialized
173 yet. */
clear_bss(void)174 void __init clear_bss(void)
175 {
176 memset(__bss_start, 0,
177 (unsigned long) __bss_stop - (unsigned long) __bss_start);
178 memset(__brk_base, 0,
179 (unsigned long) __brk_limit - (unsigned long) __brk_base);
180 }
181
get_cmd_line_ptr(void)182 static unsigned long get_cmd_line_ptr(void)
183 {
184 unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
185
186 cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
187
188 return cmd_line_ptr;
189 }
190
copy_bootdata(char * real_mode_data)191 static void __init copy_bootdata(char *real_mode_data)
192 {
193 char * command_line;
194 unsigned long cmd_line_ptr;
195
196 /*
197 * If SME is active, this will create decrypted mappings of the
198 * boot data in advance of the copy operations.
199 */
200 sme_map_bootdata(real_mode_data);
201
202 memcpy(&boot_params, real_mode_data, sizeof(boot_params));
203 sanitize_boot_params(&boot_params);
204 cmd_line_ptr = get_cmd_line_ptr();
205 if (cmd_line_ptr) {
206 command_line = __va(cmd_line_ptr);
207 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
208 }
209
210 /*
211 * The old boot data is no longer needed and won't be reserved,
212 * freeing up that memory for use by the system. If SME is active,
213 * we need to remove the mappings that were created so that the
214 * memory doesn't remain mapped as decrypted.
215 */
216 sme_unmap_bootdata(real_mode_data);
217 }
218
x86_64_start_kernel(char * real_mode_data)219 asmlinkage __visible void __init __noreturn x86_64_start_kernel(char * real_mode_data)
220 {
221 /*
222 * Build-time sanity checks on the kernel image and module
223 * area mappings. (these are purely build-time and produce no code)
224 */
225 BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
226 BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
227 BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
228 BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
229 BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
230 BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
231 MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
232 (__START_KERNEL & PGDIR_MASK)));
233 BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
234
235 cr4_init_shadow();
236
237 /* Kill off the identity-map trampoline */
238 reset_early_page_tables();
239
240 if (pgtable_l5_enabled()) {
241 page_offset_base = __PAGE_OFFSET_BASE_L5;
242 vmalloc_base = __VMALLOC_BASE_L5;
243 vmemmap_base = __VMEMMAP_BASE_L5;
244 }
245
246 clear_bss();
247
248 /*
249 * This needs to happen *before* kasan_early_init() because latter maps stuff
250 * into that page.
251 */
252 clear_page(init_top_pgt);
253
254 /*
255 * SME support may update early_pmd_flags to include the memory
256 * encryption mask, so it needs to be called before anything
257 * that may generate a page fault.
258 */
259 sme_early_init();
260
261 kasan_early_init();
262
263 /*
264 * Flush global TLB entries which could be left over from the trampoline page
265 * table.
266 *
267 * This needs to happen *after* kasan_early_init() as KASAN-enabled .configs
268 * instrument native_write_cr4() so KASAN must be initialized for that
269 * instrumentation to work.
270 */
271 __native_tlb_flush_global(this_cpu_read(cpu_tlbstate.cr4));
272
273 idt_setup_early_handler();
274
275 /* Needed before cc_platform_has() can be used for TDX */
276 tdx_early_init();
277
278 copy_bootdata(__va(real_mode_data));
279
280 /*
281 * Load microcode early on BSP.
282 */
283 load_ucode_bsp();
284
285 /* set init_top_pgt kernel high mapping*/
286 init_top_pgt[511] = early_top_pgt[511];
287
288 x86_64_start_reservations(real_mode_data);
289 }
290
x86_64_start_reservations(char * real_mode_data)291 void __init __noreturn x86_64_start_reservations(char *real_mode_data)
292 {
293 /* version is always not zero if it is copied */
294 if (!boot_params.hdr.version)
295 copy_bootdata(__va(real_mode_data));
296
297 x86_early_init_platform_quirks();
298
299 switch (boot_params.hdr.hardware_subarch) {
300 case X86_SUBARCH_INTEL_MID:
301 x86_intel_mid_early_setup();
302 break;
303 default:
304 break;
305 }
306
307 start_kernel();
308 }
309
early_setup_idt(void)310 void early_setup_idt(void)
311 {
312 void *handler = NULL;
313
314 if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
315 setup_ghcb();
316 handler = vc_boot_ghcb;
317 }
318
319 startup_64_load_idt(handler);
320 }
321