head64.c

  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 */
 49extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
 50unsigned int __initdata next_early_pgt;
 51SYM_PIC_ALIAS(next_early_pgt);
 52pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
 53
 54unsigned int __pgtable_l5_enabled __ro_after_init;
 55SYM_PIC_ALIAS(__pgtable_l5_enabled);
 56unsigned int pgdir_shift __ro_after_init = 39;
 57EXPORT_SYMBOL(pgdir_shift);
 58SYM_PIC_ALIAS(pgdir_shift);
 59unsigned int ptrs_per_p4d __ro_after_init = 1;
 60EXPORT_SYMBOL(ptrs_per_p4d);
 61SYM_PIC_ALIAS(ptrs_per_p4d);
 62
 63unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE_L4;
 64EXPORT_SYMBOL(page_offset_base);
 65unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4;
 66EXPORT_SYMBOL(vmalloc_base);
 67unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
 68EXPORT_SYMBOL(vmemmap_base);
 69
 70/* Wipe all early page tables except for the kernel symbol map */
 71static void __init reset_early_page_tables(void)
 72{
 73	memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
 74	next_early_pgt = 0;
 75	write_cr3(__sme_pa_nodebug(early_top_pgt));
 76}
 77
 78/* Create a new PMD entry */
 79bool __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
 80{
 81	unsigned long physaddr = address - __PAGE_OFFSET;
 82	pgdval_t pgd, *pgd_p;
 83	p4dval_t p4d, *p4d_p;
 84	pudval_t pud, *pud_p;
 85	pmdval_t *pmd_p;
 86
 87	/* Invalid address or early pgt is done ?  */
 88	if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
 89		return false;
 90
 91again:
 92	pgd_p = &early_top_pgt[pgd_index(address)].pgd;
 93	pgd = *pgd_p;
 94
 95	/*
 96	 * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
 97	 * critical -- __PAGE_OFFSET would point us back into the dynamic
 98	 * range and we might end up looping forever...
 99	 */
100	if (!pgtable_l5_enabled())
101		p4d_p = pgd_p;
102	else if (pgd)
103		p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
104	else {
105		if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
106			reset_early_page_tables();
107			goto again;
108		}
109
110		p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
111		memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
112		*pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
113	}
114	p4d_p += p4d_index(address);
115	p4d = *p4d_p;
116
117	if (p4d)
118		pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
119	else {
120		if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
121			reset_early_page_tables();
122			goto again;
123		}
124
125		pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
126		memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
127		*p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
128	}
129	pud_p += pud_index(address);
130	pud = *pud_p;
131
132	if (pud)
133		pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
134	else {
135		if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
136			reset_early_page_tables();
137			goto again;
138		}
139
140		pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
141		memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
142		*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
143	}
144	pmd_p[pmd_index(address)] = pmd;
145
146	return true;
147}
148
149static bool __init early_make_pgtable(unsigned long address)
150{
151	unsigned long physaddr = address - __PAGE_OFFSET;
152	pmdval_t pmd;
153
154	pmd = (physaddr & PMD_MASK) + early_pmd_flags;
155
156	return __early_make_pgtable(address, pmd);
157}
158
159void __init do_early_exception(struct pt_regs *regs, int trapnr)
160{
161	if (trapnr == X86_TRAP_PF &&
162	    early_make_pgtable(native_read_cr2()))
163		return;
164
165	if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT) &&
166	    trapnr == X86_TRAP_VC && handle_vc_boot_ghcb(regs))
167		return;
168
169	if (trapnr == X86_TRAP_VE && tdx_early_handle_ve(regs))
170		return;
171
172	early_fixup_exception(regs, trapnr);
173}
174
175/* Don't add a printk in there. printk relies on the PDA which is not initialized 
176   yet. */
177void __init clear_bss(void)
178{
179	memset(__bss_start, 0,
180	       (unsigned long) __bss_stop - (unsigned long) __bss_start);
181	memset(__brk_base, 0,
182	       (unsigned long) __brk_limit - (unsigned long) __brk_base);
183}
184
185static unsigned long get_cmd_line_ptr(void)
186{
187	unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
188
189	cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
190
191	return cmd_line_ptr;
192}
193
194static void __init copy_bootdata(char *real_mode_data)
195{
196	char * command_line;
197	unsigned long cmd_line_ptr;
198
199	/*
200	 * If SME is active, this will create decrypted mappings of the
201	 * boot data in advance of the copy operations.
202	 */
203	sme_map_bootdata(real_mode_data);
204
205	memcpy(&boot_params, real_mode_data, sizeof(boot_params));
206	sanitize_boot_params(&boot_params);
207	cmd_line_ptr = get_cmd_line_ptr();
208	if (cmd_line_ptr) {
209		command_line = __va(cmd_line_ptr);
210		memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
211	}
212
213	/*
214	 * The old boot data is no longer needed and won't be reserved,
215	 * freeing up that memory for use by the system. If SME is active,
216	 * we need to remove the mappings that were created so that the
217	 * memory doesn't remain mapped as decrypted.
218	 */
219	sme_unmap_bootdata(real_mode_data);
220}
221
222asmlinkage __visible void __init __noreturn x86_64_start_kernel(char * real_mode_data)
223{
224	/*
225	 * Build-time sanity checks on the kernel image and module
226	 * area mappings. (these are purely build-time and produce no code)
227	 */
228	BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
229	BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
230	BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
231	BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
232	BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
233	BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
234	MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
235				(__START_KERNEL & PGDIR_MASK)));
236	BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
237
238	cr4_init_shadow();
239
240	/* Kill off the identity-map trampoline */
241	reset_early_page_tables();
242
243	if (pgtable_l5_enabled()) {
244		page_offset_base	= __PAGE_OFFSET_BASE_L5;
245		vmalloc_base		= __VMALLOC_BASE_L5;
246		vmemmap_base		= __VMEMMAP_BASE_L5;
247	}
248
249	clear_bss();
250
251	/*
252	 * This needs to happen *before* kasan_early_init() because latter maps stuff
253	 * into that page.
254	 */
255	clear_page(init_top_pgt);
256
257	/*
258	 * SME support may update early_pmd_flags to include the memory
259	 * encryption mask, so it needs to be called before anything
260	 * that may generate a page fault.
261	 */
262	sme_early_init();
263
264	kasan_early_init();
265
266	/*
267	 * Flush global TLB entries which could be left over from the trampoline page
268	 * table.
269	 *
270	 * This needs to happen *after* kasan_early_init() as KASAN-enabled .configs
271	 * instrument native_write_cr4() so KASAN must be initialized for that
272	 * instrumentation to work.
273	 */
274	__native_tlb_flush_global(this_cpu_read(cpu_tlbstate.cr4));
275
276	idt_setup_early_handler();
277
278	/* Needed before cc_platform_has() can be used for TDX */
279	tdx_early_init();
280
281	copy_bootdata(__va(real_mode_data));
282
283	/*
284	 * Load microcode early on BSP.
285	 */
286	load_ucode_bsp();
287
288	/* set init_top_pgt kernel high mapping*/
289	init_top_pgt[511] = early_top_pgt[511];
290
291	x86_64_start_reservations(real_mode_data);
292}
293
294void __init __noreturn x86_64_start_reservations(char *real_mode_data)
295{
296	/* version is always not zero if it is copied */
297	if (!boot_params.hdr.version)
298		copy_bootdata(__va(real_mode_data));
299
300	x86_early_init_platform_quirks();
301
302	switch (boot_params.hdr.hardware_subarch) {
303	case X86_SUBARCH_INTEL_MID:
304		x86_intel_mid_early_setup();
305		break;
306	default:
307		break;
308	}
309
310	start_kernel();
311}
312
313void early_setup_idt(void)
314{
315	void *handler = NULL;
316
317	if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
318		setup_ghcb();
319		handler = vc_boot_ghcb;
320	}
321
322	__pi_startup_64_load_idt(handler);
323}