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1/*
2 * linux/arch/x86_64/kernel/head.S -- start in 32bit and switch to 64bit
3 *
4 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
5 * Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
6 * Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
7 * Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
8 * Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com>
9 */
10
11
12#include <linux/linkage.h>
13#include <linux/threads.h>
14#include <linux/init.h>
15#include <asm/segment.h>
16#include <asm/pgtable.h>
17#include <asm/page.h>
18#include <asm/msr.h>
19#include <asm/cache.h>
20#include <asm/processor-flags.h>
21#include <asm/percpu.h>
22#include <asm/nops.h>
23
24#ifdef CONFIG_PARAVIRT
25#include <asm/asm-offsets.h>
26#include <asm/paravirt.h>
27#define GET_CR2_INTO(reg) GET_CR2_INTO_RAX ; movq %rax, reg
28#else
29#define GET_CR2_INTO(reg) movq %cr2, reg
30#define INTERRUPT_RETURN iretq
31#endif
32
33/* we are not able to switch in one step to the final KERNEL ADDRESS SPACE
34 * because we need identity-mapped pages.
35 *
36 */
37
38#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
39
40L4_PAGE_OFFSET = pgd_index(__PAGE_OFFSET)
41L3_PAGE_OFFSET = pud_index(__PAGE_OFFSET)
42L4_START_KERNEL = pgd_index(__START_KERNEL_map)
43L3_START_KERNEL = pud_index(__START_KERNEL_map)
44
45 .text
46 __HEAD
47 .code64
48 .globl startup_64
49startup_64:
50
51 /*
52 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 1,
53 * and someone has loaded an identity mapped page table
54 * for us. These identity mapped page tables map all of the
55 * kernel pages and possibly all of memory.
56 *
57 * %esi holds a physical pointer to real_mode_data.
58 *
59 * We come here either directly from a 64bit bootloader, or from
60 * arch/x86_64/boot/compressed/head.S.
61 *
62 * We only come here initially at boot nothing else comes here.
63 *
64 * Since we may be loaded at an address different from what we were
65 * compiled to run at we first fixup the physical addresses in our page
66 * tables and then reload them.
67 */
68
69 /* Compute the delta between the address I am compiled to run at and the
70 * address I am actually running at.
71 */
72 leaq _text(%rip), %rbp
73 subq $_text - __START_KERNEL_map, %rbp
74
75 /* Is the address not 2M aligned? */
76 movq %rbp, %rax
77 andl $~PMD_PAGE_MASK, %eax
78 testl %eax, %eax
79 jnz bad_address
80
81 /* Is the address too large? */
82 leaq _text(%rip), %rdx
83 movq $PGDIR_SIZE, %rax
84 cmpq %rax, %rdx
85 jae bad_address
86
87 /* Fixup the physical addresses in the page table
88 */
89 addq %rbp, init_level4_pgt + 0(%rip)
90 addq %rbp, init_level4_pgt + (L4_PAGE_OFFSET*8)(%rip)
91 addq %rbp, init_level4_pgt + (L4_START_KERNEL*8)(%rip)
92
93 addq %rbp, level3_ident_pgt + 0(%rip)
94
95 addq %rbp, level3_kernel_pgt + (510*8)(%rip)
96 addq %rbp, level3_kernel_pgt + (511*8)(%rip)
97
98 addq %rbp, level2_fixmap_pgt + (506*8)(%rip)
99
100 /* Add an Identity mapping if I am above 1G */
101 leaq _text(%rip), %rdi
102 andq $PMD_PAGE_MASK, %rdi
103
104 movq %rdi, %rax
105 shrq $PUD_SHIFT, %rax
106 andq $(PTRS_PER_PUD - 1), %rax
107 jz ident_complete
108
109 leaq (level2_spare_pgt - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx
110 leaq level3_ident_pgt(%rip), %rbx
111 movq %rdx, 0(%rbx, %rax, 8)
112
113 movq %rdi, %rax
114 shrq $PMD_SHIFT, %rax
115 andq $(PTRS_PER_PMD - 1), %rax
116 leaq __PAGE_KERNEL_IDENT_LARGE_EXEC(%rdi), %rdx
117 leaq level2_spare_pgt(%rip), %rbx
118 movq %rdx, 0(%rbx, %rax, 8)
119ident_complete:
120
121 /*
122 * Fixup the kernel text+data virtual addresses. Note that
123 * we might write invalid pmds, when the kernel is relocated
124 * cleanup_highmap() fixes this up along with the mappings
125 * beyond _end.
126 */
127
128 leaq level2_kernel_pgt(%rip), %rdi
129 leaq 4096(%rdi), %r8
130 /* See if it is a valid page table entry */
1311: testq $1, 0(%rdi)
132 jz 2f
133 addq %rbp, 0(%rdi)
134 /* Go to the next page */
1352: addq $8, %rdi
136 cmp %r8, %rdi
137 jne 1b
138
139 /* Fixup phys_base */
140 addq %rbp, phys_base(%rip)
141
142 /* Due to ENTRY(), sometimes the empty space gets filled with
143 * zeros. Better take a jmp than relying on empty space being
144 * filled with 0x90 (nop)
145 */
146 jmp secondary_startup_64
147ENTRY(secondary_startup_64)
148 /*
149 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 1,
150 * and someone has loaded a mapped page table.
151 *
152 * %esi holds a physical pointer to real_mode_data.
153 *
154 * We come here either from startup_64 (using physical addresses)
155 * or from trampoline.S (using virtual addresses).
156 *
157 * Using virtual addresses from trampoline.S removes the need
158 * to have any identity mapped pages in the kernel page table
159 * after the boot processor executes this code.
160 */
161
162 /* Enable PAE mode and PGE */
163 movl $(X86_CR4_PAE | X86_CR4_PGE), %eax
164 movq %rax, %cr4
165
166 /* Setup early boot stage 4 level pagetables. */
167 movq $(init_level4_pgt - __START_KERNEL_map), %rax
168 addq phys_base(%rip), %rax
169 movq %rax, %cr3
170
171 /* Ensure I am executing from virtual addresses */
172 movq $1f, %rax
173 jmp *%rax
1741:
175
176 /* Check if nx is implemented */
177 movl $0x80000001, %eax
178 cpuid
179 movl %edx,%edi
180
181 /* Setup EFER (Extended Feature Enable Register) */
182 movl $MSR_EFER, %ecx
183 rdmsr
184 btsl $_EFER_SCE, %eax /* Enable System Call */
185 btl $20,%edi /* No Execute supported? */
186 jnc 1f
187 btsl $_EFER_NX, %eax
1881: wrmsr /* Make changes effective */
189
190 /* Setup cr0 */
191#define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \
192 X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \
193 X86_CR0_PG)
194 movl $CR0_STATE, %eax
195 /* Make changes effective */
196 movq %rax, %cr0
197
198 /* Setup a boot time stack */
199 movq stack_start(%rip),%rsp
200
201 /* zero EFLAGS after setting rsp */
202 pushq $0
203 popfq
204
205 /*
206 * We must switch to a new descriptor in kernel space for the GDT
207 * because soon the kernel won't have access anymore to the userspace
208 * addresses where we're currently running on. We have to do that here
209 * because in 32bit we couldn't load a 64bit linear address.
210 */
211 lgdt early_gdt_descr(%rip)
212
213 /* set up data segments */
214 xorl %eax,%eax
215 movl %eax,%ds
216 movl %eax,%ss
217 movl %eax,%es
218
219 /*
220 * We don't really need to load %fs or %gs, but load them anyway
221 * to kill any stale realmode selectors. This allows execution
222 * under VT hardware.
223 */
224 movl %eax,%fs
225 movl %eax,%gs
226
227 /* Set up %gs.
228 *
229 * The base of %gs always points to the bottom of the irqstack
230 * union. If the stack protector canary is enabled, it is
231 * located at %gs:40. Note that, on SMP, the boot cpu uses
232 * init data section till per cpu areas are set up.
233 */
234 movl $MSR_GS_BASE,%ecx
235 movl initial_gs(%rip),%eax
236 movl initial_gs+4(%rip),%edx
237 wrmsr
238
239 /* esi is pointer to real mode structure with interesting info.
240 pass it to C */
241 movl %esi, %edi
242
243 /* Finally jump to run C code and to be on real kernel address
244 * Since we are running on identity-mapped space we have to jump
245 * to the full 64bit address, this is only possible as indirect
246 * jump. In addition we need to ensure %cs is set so we make this
247 * a far return.
248 */
249 movq initial_code(%rip),%rax
250 pushq $0 # fake return address to stop unwinder
251 pushq $__KERNEL_CS # set correct cs
252 pushq %rax # target address in negative space
253 lretq
254
255 /* SMP bootup changes these two */
256 __REFDATA
257 .align 8
258 ENTRY(initial_code)
259 .quad x86_64_start_kernel
260 ENTRY(initial_gs)
261 .quad INIT_PER_CPU_VAR(irq_stack_union)
262
263 ENTRY(stack_start)
264 .quad init_thread_union+THREAD_SIZE-8
265 .word 0
266 __FINITDATA
267
268bad_address:
269 jmp bad_address
270
271 .section ".init.text","ax"
272 .globl early_idt_handlers
273early_idt_handlers:
274 # 104(%rsp) %rflags
275 # 96(%rsp) %cs
276 # 88(%rsp) %rip
277 # 80(%rsp) error code
278 i = 0
279 .rept NUM_EXCEPTION_VECTORS
280 .if (EXCEPTION_ERRCODE_MASK >> i) & 1
281 ASM_NOP2
282 .else
283 pushq $0 # Dummy error code, to make stack frame uniform
284 .endif
285 pushq $i # 72(%rsp) Vector number
286 jmp early_idt_handler
287 i = i + 1
288 .endr
289
290ENTRY(early_idt_handler)
291 cld
292
293 cmpl $2,early_recursion_flag(%rip)
294 jz 1f
295 incl early_recursion_flag(%rip)
296
297 pushq %rax # 64(%rsp)
298 pushq %rcx # 56(%rsp)
299 pushq %rdx # 48(%rsp)
300 pushq %rsi # 40(%rsp)
301 pushq %rdi # 32(%rsp)
302 pushq %r8 # 24(%rsp)
303 pushq %r9 # 16(%rsp)
304 pushq %r10 # 8(%rsp)
305 pushq %r11 # 0(%rsp)
306
307 cmpl $__KERNEL_CS,96(%rsp)
308 jne 10f
309
310 leaq 88(%rsp),%rdi # Pointer to %rip
311 call early_fixup_exception
312 andl %eax,%eax
313 jnz 20f # Found an exception entry
314
31510:
316#ifdef CONFIG_EARLY_PRINTK
317 GET_CR2_INTO(%r9) # can clobber any volatile register if pv
318 movl 80(%rsp),%r8d # error code
319 movl 72(%rsp),%esi # vector number
320 movl 96(%rsp),%edx # %cs
321 movq 88(%rsp),%rcx # %rip
322 xorl %eax,%eax
323 leaq early_idt_msg(%rip),%rdi
324 call early_printk
325 cmpl $2,early_recursion_flag(%rip)
326 jz 1f
327 call dump_stack
328#ifdef CONFIG_KALLSYMS
329 leaq early_idt_ripmsg(%rip),%rdi
330 movq 40(%rsp),%rsi # %rip again
331 call __print_symbol
332#endif
333#endif /* EARLY_PRINTK */
3341: hlt
335 jmp 1b
336
33720: # Exception table entry found
338 popq %r11
339 popq %r10
340 popq %r9
341 popq %r8
342 popq %rdi
343 popq %rsi
344 popq %rdx
345 popq %rcx
346 popq %rax
347 addq $16,%rsp # drop vector number and error code
348 decl early_recursion_flag(%rip)
349 INTERRUPT_RETURN
350
351 .balign 4
352early_recursion_flag:
353 .long 0
354
355#ifdef CONFIG_EARLY_PRINTK
356early_idt_msg:
357 .asciz "PANIC: early exception %02lx rip %lx:%lx error %lx cr2 %lx\n"
358early_idt_ripmsg:
359 .asciz "RIP %s\n"
360#endif /* CONFIG_EARLY_PRINTK */
361 .previous
362
363#define NEXT_PAGE(name) \
364 .balign PAGE_SIZE; \
365ENTRY(name)
366
367/* Automate the creation of 1 to 1 mapping pmd entries */
368#define PMDS(START, PERM, COUNT) \
369 i = 0 ; \
370 .rept (COUNT) ; \
371 .quad (START) + (i << PMD_SHIFT) + (PERM) ; \
372 i = i + 1 ; \
373 .endr
374
375 .data
376 /*
377 * This default setting generates an ident mapping at address 0x100000
378 * and a mapping for the kernel that precisely maps virtual address
379 * 0xffffffff80000000 to physical address 0x000000. (always using
380 * 2Mbyte large pages provided by PAE mode)
381 */
382NEXT_PAGE(init_level4_pgt)
383 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
384 .org init_level4_pgt + L4_PAGE_OFFSET*8, 0
385 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
386 .org init_level4_pgt + L4_START_KERNEL*8, 0
387 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
388 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
389
390NEXT_PAGE(level3_ident_pgt)
391 .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
392 .fill 511,8,0
393
394NEXT_PAGE(level3_kernel_pgt)
395 .fill L3_START_KERNEL,8,0
396 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
397 .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
398 .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
399
400NEXT_PAGE(level2_fixmap_pgt)
401 .fill 506,8,0
402 .quad level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
403 /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
404 .fill 5,8,0
405
406NEXT_PAGE(level1_fixmap_pgt)
407 .fill 512,8,0
408
409NEXT_PAGE(level2_ident_pgt)
410 /* Since I easily can, map the first 1G.
411 * Don't set NX because code runs from these pages.
412 */
413 PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
414
415NEXT_PAGE(level2_kernel_pgt)
416 /*
417 * 512 MB kernel mapping. We spend a full page on this pagetable
418 * anyway.
419 *
420 * The kernel code+data+bss must not be bigger than that.
421 *
422 * (NOTE: at +512MB starts the module area, see MODULES_VADDR.
423 * If you want to increase this then increase MODULES_VADDR
424 * too.)
425 */
426 PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
427 KERNEL_IMAGE_SIZE/PMD_SIZE)
428
429NEXT_PAGE(level2_spare_pgt)
430 .fill 512, 8, 0
431
432#undef PMDS
433#undef NEXT_PAGE
434
435 .data
436 .align 16
437 .globl early_gdt_descr
438early_gdt_descr:
439 .word GDT_ENTRIES*8-1
440early_gdt_descr_base:
441 .quad INIT_PER_CPU_VAR(gdt_page)
442
443ENTRY(phys_base)
444 /* This must match the first entry in level2_kernel_pgt */
445 .quad 0x0000000000000000
446
447#include "../../x86/xen/xen-head.S"
448
449 .section .bss, "aw", @nobits
450 .align L1_CACHE_BYTES
451ENTRY(idt_table)
452 .skip IDT_ENTRIES * 16
453
454 .align L1_CACHE_BYTES
455ENTRY(nmi_idt_table)
456 .skip IDT_ENTRIES * 16
457
458 __PAGE_ALIGNED_BSS
459 .align PAGE_SIZE
460ENTRY(empty_zero_page)
461 .skip PAGE_SIZE
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * linux/arch/x86/kernel/head_64.S -- start in 32bit and switch to 64bit
4 *
5 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
6 * Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
7 * Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
8 * Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
9 * Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com>
10 */
11
12#include <linux/export.h>
13#include <linux/linkage.h>
14#include <linux/threads.h>
15#include <linux/init.h>
16#include <linux/pgtable.h>
17#include <asm/segment.h>
18#include <asm/page.h>
19#include <asm/msr.h>
20#include <asm/cache.h>
21#include <asm/processor-flags.h>
22#include <asm/percpu.h>
23#include <asm/nops.h>
24#include "../entry/calling.h"
25#include <asm/nospec-branch.h>
26#include <asm/apicdef.h>
27#include <asm/fixmap.h>
28#include <asm/smp.h>
29#include <asm/thread_info.h>
30
31/*
32 * We are not able to switch in one step to the final KERNEL ADDRESS SPACE
33 * because we need identity-mapped pages.
34 */
35#define l4_index(x) (((x) >> 39) & 511)
36#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
37
38L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE_L4)
39L4_START_KERNEL = l4_index(__START_KERNEL_map)
40
41L3_START_KERNEL = pud_index(__START_KERNEL_map)
42
43 __HEAD
44 .code64
45SYM_CODE_START_NOALIGN(startup_64)
46 UNWIND_HINT_END_OF_STACK
47 /*
48 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
49 * and someone has loaded an identity mapped page table
50 * for us. These identity mapped page tables map all of the
51 * kernel pages and possibly all of memory.
52 *
53 * %RSI holds the physical address of the boot_params structure
54 * provided by the bootloader. Preserve it in %R15 so C function calls
55 * will not clobber it.
56 *
57 * We come here either directly from a 64bit bootloader, or from
58 * arch/x86/boot/compressed/head_64.S.
59 *
60 * We only come here initially at boot nothing else comes here.
61 *
62 * Since we may be loaded at an address different from what we were
63 * compiled to run at we first fixup the physical addresses in our page
64 * tables and then reload them.
65 */
66 mov %rsi, %r15
67
68 /* Set up the stack for verify_cpu() */
69 leaq (__end_init_task - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE)(%rip), %rsp
70
71 /* Setup GSBASE to allow stack canary access for C code */
72 movl $MSR_GS_BASE, %ecx
73 leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
74 movl %edx, %eax
75 shrq $32, %rdx
76 wrmsr
77
78 call startup_64_setup_gdt_idt
79
80 /* Now switch to __KERNEL_CS so IRET works reliably */
81 pushq $__KERNEL_CS
82 leaq .Lon_kernel_cs(%rip), %rax
83 pushq %rax
84 lretq
85
86.Lon_kernel_cs:
87 UNWIND_HINT_END_OF_STACK
88
89#ifdef CONFIG_AMD_MEM_ENCRYPT
90 /*
91 * Activate SEV/SME memory encryption if supported/enabled. This needs to
92 * be done now, since this also includes setup of the SEV-SNP CPUID table,
93 * which needs to be done before any CPUID instructions are executed in
94 * subsequent code. Pass the boot_params pointer as the first argument.
95 */
96 movq %r15, %rdi
97 call sme_enable
98#endif
99
100 /* Sanitize CPU configuration */
101 call verify_cpu
102
103 /*
104 * Perform pagetable fixups. Additionally, if SME is active, encrypt
105 * the kernel and retrieve the modifier (SME encryption mask if SME
106 * is active) to be added to the initial pgdir entry that will be
107 * programmed into CR3.
108 */
109 leaq _text(%rip), %rdi
110 movq %r15, %rsi
111 call __startup_64
112
113 /* Form the CR3 value being sure to include the CR3 modifier */
114 leaq early_top_pgt(%rip), %rcx
115 addq %rcx, %rax
116
117#ifdef CONFIG_AMD_MEM_ENCRYPT
118 mov %rax, %rdi
119
120 /*
121 * For SEV guests: Verify that the C-bit is correct. A malicious
122 * hypervisor could lie about the C-bit position to perform a ROP
123 * attack on the guest by writing to the unencrypted stack and wait for
124 * the next RET instruction.
125 */
126 call sev_verify_cbit
127#endif
128
129 /*
130 * Switch to early_top_pgt which still has the identity mappings
131 * present.
132 */
133 movq %rax, %cr3
134
135 /* Branch to the common startup code at its kernel virtual address */
136 ANNOTATE_RETPOLINE_SAFE
137 jmp *0f(%rip)
138SYM_CODE_END(startup_64)
139
140 __INITRODATA
1410: .quad common_startup_64
142
143 .text
144SYM_CODE_START(secondary_startup_64)
145 UNWIND_HINT_END_OF_STACK
146 ANNOTATE_NOENDBR
147 /*
148 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
149 * and someone has loaded a mapped page table.
150 *
151 * We come here either from startup_64 (using physical addresses)
152 * or from trampoline.S (using virtual addresses).
153 *
154 * Using virtual addresses from trampoline.S removes the need
155 * to have any identity mapped pages in the kernel page table
156 * after the boot processor executes this code.
157 */
158
159 /* Sanitize CPU configuration */
160 call verify_cpu
161
162 /*
163 * The secondary_startup_64_no_verify entry point is only used by
164 * SEV-ES guests. In those guests the call to verify_cpu() would cause
165 * #VC exceptions which can not be handled at this stage of secondary
166 * CPU bringup.
167 *
168 * All non SEV-ES systems, especially Intel systems, need to execute
169 * verify_cpu() above to make sure NX is enabled.
170 */
171SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
172 UNWIND_HINT_END_OF_STACK
173 ANNOTATE_NOENDBR
174
175 /* Clear %R15 which holds the boot_params pointer on the boot CPU */
176 xorl %r15d, %r15d
177
178 /* Derive the runtime physical address of init_top_pgt[] */
179 movq phys_base(%rip), %rax
180 addq $(init_top_pgt - __START_KERNEL_map), %rax
181
182 /*
183 * Retrieve the modifier (SME encryption mask if SME is active) to be
184 * added to the initial pgdir entry that will be programmed into CR3.
185 */
186#ifdef CONFIG_AMD_MEM_ENCRYPT
187 addq sme_me_mask(%rip), %rax
188#endif
189 /*
190 * Switch to the init_top_pgt here, away from the trampoline_pgd and
191 * unmap the identity mapped ranges.
192 */
193 movq %rax, %cr3
194
195SYM_INNER_LABEL(common_startup_64, SYM_L_LOCAL)
196 UNWIND_HINT_END_OF_STACK
197 ANNOTATE_NOENDBR
198
199 /*
200 * Create a mask of CR4 bits to preserve. Omit PGE in order to flush
201 * global 1:1 translations from the TLBs.
202 *
203 * From the SDM:
204 * "If CR4.PGE is changing from 0 to 1, there were no global TLB
205 * entries before the execution; if CR4.PGE is changing from 1 to 0,
206 * there will be no global TLB entries after the execution."
207 */
208 movl $(X86_CR4_PAE | X86_CR4_LA57), %edx
209#ifdef CONFIG_X86_MCE
210 /*
211 * Preserve CR4.MCE if the kernel will enable #MC support.
212 * Clearing MCE may fault in some environments (that also force #MC
213 * support). Any machine check that occurs before #MC support is fully
214 * configured will crash the system regardless of the CR4.MCE value set
215 * here.
216 */
217 orl $X86_CR4_MCE, %edx
218#endif
219 movq %cr4, %rcx
220 andl %edx, %ecx
221
222 /* Even if ignored in long mode, set PSE uniformly on all logical CPUs. */
223 btsl $X86_CR4_PSE_BIT, %ecx
224 movq %rcx, %cr4
225
226 /*
227 * Set CR4.PGE to re-enable global translations.
228 */
229 btsl $X86_CR4_PGE_BIT, %ecx
230 movq %rcx, %cr4
231
232#ifdef CONFIG_SMP
233 /*
234 * For parallel boot, the APIC ID is read from the APIC, and then
235 * used to look up the CPU number. For booting a single CPU, the
236 * CPU number is encoded in smpboot_control.
237 *
238 * Bit 31 STARTUP_READ_APICID (Read APICID from APIC)
239 * Bit 0-23 CPU# if STARTUP_xx flags are not set
240 */
241 movl smpboot_control(%rip), %ecx
242 testl $STARTUP_READ_APICID, %ecx
243 jnz .Lread_apicid
244 /*
245 * No control bit set, single CPU bringup. CPU number is provided
246 * in bit 0-23. This is also the boot CPU case (CPU number 0).
247 */
248 andl $(~STARTUP_PARALLEL_MASK), %ecx
249 jmp .Lsetup_cpu
250
251.Lread_apicid:
252 /* Check whether X2APIC mode is already enabled */
253 mov $MSR_IA32_APICBASE, %ecx
254 rdmsr
255 testl $X2APIC_ENABLE, %eax
256 jnz .Lread_apicid_msr
257
258#ifdef CONFIG_X86_X2APIC
259 /*
260 * If system is in X2APIC mode then MMIO base might not be
261 * mapped causing the MMIO read below to fault. Faults can't
262 * be handled at that point.
263 */
264 cmpl $0, x2apic_mode(%rip)
265 jz .Lread_apicid_mmio
266
267 /* Force the AP into X2APIC mode. */
268 orl $X2APIC_ENABLE, %eax
269 wrmsr
270 jmp .Lread_apicid_msr
271#endif
272
273.Lread_apicid_mmio:
274 /* Read the APIC ID from the fix-mapped MMIO space. */
275 movq apic_mmio_base(%rip), %rcx
276 addq $APIC_ID, %rcx
277 movl (%rcx), %eax
278 shr $24, %eax
279 jmp .Llookup_AP
280
281.Lread_apicid_msr:
282 mov $APIC_X2APIC_ID_MSR, %ecx
283 rdmsr
284
285.Llookup_AP:
286 /* EAX contains the APIC ID of the current CPU */
287 xorl %ecx, %ecx
288 leaq cpuid_to_apicid(%rip), %rbx
289
290.Lfind_cpunr:
291 cmpl (%rbx,%rcx,4), %eax
292 jz .Lsetup_cpu
293 inc %ecx
294#ifdef CONFIG_FORCE_NR_CPUS
295 cmpl $NR_CPUS, %ecx
296#else
297 cmpl nr_cpu_ids(%rip), %ecx
298#endif
299 jb .Lfind_cpunr
300
301 /* APIC ID not found in the table. Drop the trampoline lock and bail. */
302 movq trampoline_lock(%rip), %rax
303 movl $0, (%rax)
304
3051: cli
306 hlt
307 jmp 1b
308
309.Lsetup_cpu:
310 /* Get the per cpu offset for the given CPU# which is in ECX */
311 movq __per_cpu_offset(,%rcx,8), %rdx
312#else
313 xorl %edx, %edx /* zero-extended to clear all of RDX */
314#endif /* CONFIG_SMP */
315
316 /*
317 * Setup a boot time stack - Any secondary CPU will have lost its stack
318 * by now because the cr3-switch above unmaps the real-mode stack.
319 *
320 * RDX contains the per-cpu offset
321 */
322 movq pcpu_hot + X86_current_task(%rdx), %rax
323 movq TASK_threadsp(%rax), %rsp
324
325 /*
326 * Now that this CPU is running on its own stack, drop the realmode
327 * protection. For the boot CPU the pointer is NULL!
328 */
329 movq trampoline_lock(%rip), %rax
330 testq %rax, %rax
331 jz .Lsetup_gdt
332 movl $0, (%rax)
333
334.Lsetup_gdt:
335 /*
336 * We must switch to a new descriptor in kernel space for the GDT
337 * because soon the kernel won't have access anymore to the userspace
338 * addresses where we're currently running on. We have to do that here
339 * because in 32bit we couldn't load a 64bit linear address.
340 */
341 subq $16, %rsp
342 movw $(GDT_SIZE-1), (%rsp)
343 leaq gdt_page(%rdx), %rax
344 movq %rax, 2(%rsp)
345 lgdt (%rsp)
346 addq $16, %rsp
347
348 /* set up data segments */
349 xorl %eax,%eax
350 movl %eax,%ds
351 movl %eax,%ss
352 movl %eax,%es
353
354 /*
355 * We don't really need to load %fs or %gs, but load them anyway
356 * to kill any stale realmode selectors. This allows execution
357 * under VT hardware.
358 */
359 movl %eax,%fs
360 movl %eax,%gs
361
362 /* Set up %gs.
363 *
364 * The base of %gs always points to fixed_percpu_data. If the
365 * stack protector canary is enabled, it is located at %gs:40.
366 * Note that, on SMP, the boot cpu uses init data section until
367 * the per cpu areas are set up.
368 */
369 movl $MSR_GS_BASE,%ecx
370#ifndef CONFIG_SMP
371 leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
372#endif
373 movl %edx, %eax
374 shrq $32, %rdx
375 wrmsr
376
377 /* Setup and Load IDT */
378 call early_setup_idt
379
380 /* Check if nx is implemented */
381 movl $0x80000001, %eax
382 cpuid
383 movl %edx,%edi
384
385 /* Setup EFER (Extended Feature Enable Register) */
386 movl $MSR_EFER, %ecx
387 rdmsr
388 /*
389 * Preserve current value of EFER for comparison and to skip
390 * EFER writes if no change was made (for TDX guest)
391 */
392 movl %eax, %edx
393 btsl $_EFER_SCE, %eax /* Enable System Call */
394 btl $20,%edi /* No Execute supported? */
395 jnc 1f
396 btsl $_EFER_NX, %eax
397 btsq $_PAGE_BIT_NX,early_pmd_flags(%rip)
398
399 /* Avoid writing EFER if no change was made (for TDX guest) */
4001: cmpl %edx, %eax
401 je 1f
402 xor %edx, %edx
403 wrmsr /* Make changes effective */
4041:
405 /* Setup cr0 */
406 movl $CR0_STATE, %eax
407 /* Make changes effective */
408 movq %rax, %cr0
409
410 /* zero EFLAGS after setting rsp */
411 pushq $0
412 popfq
413
414 /* Pass the boot_params pointer as first argument */
415 movq %r15, %rdi
416
417.Ljump_to_C_code:
418 xorl %ebp, %ebp # clear frame pointer
419 ANNOTATE_RETPOLINE_SAFE
420 callq *initial_code(%rip)
421 ud2
422SYM_CODE_END(secondary_startup_64)
423
424#include "verify_cpu.S"
425#include "sev_verify_cbit.S"
426
427#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_AMD_MEM_ENCRYPT)
428/*
429 * Entry point for soft restart of a CPU. Invoked from xxx_play_dead() for
430 * restarting the boot CPU or for restarting SEV guest CPUs after CPU hot
431 * unplug. Everything is set up already except the stack.
432 */
433SYM_CODE_START(soft_restart_cpu)
434 ANNOTATE_NOENDBR
435 UNWIND_HINT_END_OF_STACK
436
437 /* Find the idle task stack */
438 movq PER_CPU_VAR(pcpu_hot + X86_current_task), %rcx
439 movq TASK_threadsp(%rcx), %rsp
440
441 jmp .Ljump_to_C_code
442SYM_CODE_END(soft_restart_cpu)
443#endif
444
445#ifdef CONFIG_AMD_MEM_ENCRYPT
446/*
447 * VC Exception handler used during early boot when running on kernel
448 * addresses, but before the switch to the idt_table can be made.
449 * The early_idt_handler_array can't be used here because it calls into a lot
450 * of __init code and this handler is also used during CPU offlining/onlining.
451 * Therefore this handler ends up in the .text section so that it stays around
452 * when .init.text is freed.
453 */
454SYM_CODE_START_NOALIGN(vc_boot_ghcb)
455 UNWIND_HINT_IRET_REGS offset=8
456 ENDBR
457
458 /* Build pt_regs */
459 PUSH_AND_CLEAR_REGS
460
461 /* Call C handler */
462 movq %rsp, %rdi
463 movq ORIG_RAX(%rsp), %rsi
464 movq initial_vc_handler(%rip), %rax
465 ANNOTATE_RETPOLINE_SAFE
466 call *%rax
467
468 /* Unwind pt_regs */
469 POP_REGS
470
471 /* Remove Error Code */
472 addq $8, %rsp
473
474 iretq
475SYM_CODE_END(vc_boot_ghcb)
476#endif
477
478 /* Both SMP bootup and ACPI suspend change these variables */
479 __REFDATA
480 .balign 8
481SYM_DATA(initial_code, .quad x86_64_start_kernel)
482#ifdef CONFIG_AMD_MEM_ENCRYPT
483SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb)
484#endif
485
486SYM_DATA(trampoline_lock, .quad 0);
487 __FINITDATA
488
489 __INIT
490SYM_CODE_START(early_idt_handler_array)
491 i = 0
492 .rept NUM_EXCEPTION_VECTORS
493 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
494 UNWIND_HINT_IRET_REGS
495 ENDBR
496 pushq $0 # Dummy error code, to make stack frame uniform
497 .else
498 UNWIND_HINT_IRET_REGS offset=8
499 ENDBR
500 .endif
501 pushq $i # 72(%rsp) Vector number
502 jmp early_idt_handler_common
503 UNWIND_HINT_IRET_REGS
504 i = i + 1
505 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
506 .endr
507SYM_CODE_END(early_idt_handler_array)
508 ANNOTATE_NOENDBR // early_idt_handler_array[NUM_EXCEPTION_VECTORS]
509
510SYM_CODE_START_LOCAL(early_idt_handler_common)
511 UNWIND_HINT_IRET_REGS offset=16
512 /*
513 * The stack is the hardware frame, an error code or zero, and the
514 * vector number.
515 */
516 cld
517
518 incl early_recursion_flag(%rip)
519
520 /* The vector number is currently in the pt_regs->di slot. */
521 pushq %rsi /* pt_regs->si */
522 movq 8(%rsp), %rsi /* RSI = vector number */
523 movq %rdi, 8(%rsp) /* pt_regs->di = RDI */
524 pushq %rdx /* pt_regs->dx */
525 pushq %rcx /* pt_regs->cx */
526 pushq %rax /* pt_regs->ax */
527 pushq %r8 /* pt_regs->r8 */
528 pushq %r9 /* pt_regs->r9 */
529 pushq %r10 /* pt_regs->r10 */
530 pushq %r11 /* pt_regs->r11 */
531 pushq %rbx /* pt_regs->bx */
532 pushq %rbp /* pt_regs->bp */
533 pushq %r12 /* pt_regs->r12 */
534 pushq %r13 /* pt_regs->r13 */
535 pushq %r14 /* pt_regs->r14 */
536 pushq %r15 /* pt_regs->r15 */
537 UNWIND_HINT_REGS
538
539 movq %rsp,%rdi /* RDI = pt_regs; RSI is already trapnr */
540 call do_early_exception
541
542 decl early_recursion_flag(%rip)
543 jmp restore_regs_and_return_to_kernel
544SYM_CODE_END(early_idt_handler_common)
545
546#ifdef CONFIG_AMD_MEM_ENCRYPT
547/*
548 * VC Exception handler used during very early boot. The
549 * early_idt_handler_array can't be used because it returns via the
550 * paravirtualized INTERRUPT_RETURN and pv-ops don't work that early.
551 *
552 * XXX it does, fix this.
553 *
554 * This handler will end up in the .init.text section and not be
555 * available to boot secondary CPUs.
556 */
557SYM_CODE_START_NOALIGN(vc_no_ghcb)
558 UNWIND_HINT_IRET_REGS offset=8
559 ENDBR
560
561 /* Build pt_regs */
562 PUSH_AND_CLEAR_REGS
563
564 /* Call C handler */
565 movq %rsp, %rdi
566 movq ORIG_RAX(%rsp), %rsi
567 call do_vc_no_ghcb
568
569 /* Unwind pt_regs */
570 POP_REGS
571
572 /* Remove Error Code */
573 addq $8, %rsp
574
575 /* Pure iret required here - don't use INTERRUPT_RETURN */
576 iretq
577SYM_CODE_END(vc_no_ghcb)
578#endif
579
580#define SYM_DATA_START_PAGE_ALIGNED(name) \
581 SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE)
582
583#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
584/*
585 * Each PGD needs to be 8k long and 8k aligned. We do not
586 * ever go out to userspace with these, so we do not
587 * strictly *need* the second page, but this allows us to
588 * have a single set_pgd() implementation that does not
589 * need to worry about whether it has 4k or 8k to work
590 * with.
591 *
592 * This ensures PGDs are 8k long:
593 */
594#define PTI_USER_PGD_FILL 512
595/* This ensures they are 8k-aligned: */
596#define SYM_DATA_START_PTI_ALIGNED(name) \
597 SYM_START(name, SYM_L_GLOBAL, .balign 2 * PAGE_SIZE)
598#else
599#define SYM_DATA_START_PTI_ALIGNED(name) \
600 SYM_DATA_START_PAGE_ALIGNED(name)
601#define PTI_USER_PGD_FILL 0
602#endif
603
604/* Automate the creation of 1 to 1 mapping pmd entries */
605#define PMDS(START, PERM, COUNT) \
606 i = 0 ; \
607 .rept (COUNT) ; \
608 .quad (START) + (i << PMD_SHIFT) + (PERM) ; \
609 i = i + 1 ; \
610 .endr
611
612 __INITDATA
613 .balign 4
614
615SYM_DATA_START_PTI_ALIGNED(early_top_pgt)
616 .fill 511,8,0
617 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
618 .fill PTI_USER_PGD_FILL,8,0
619SYM_DATA_END(early_top_pgt)
620
621SYM_DATA_START_PAGE_ALIGNED(early_dynamic_pgts)
622 .fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
623SYM_DATA_END(early_dynamic_pgts)
624
625SYM_DATA(early_recursion_flag, .long 0)
626
627 .data
628
629#if defined(CONFIG_XEN_PV) || defined(CONFIG_PVH)
630SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
631 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
632 .org init_top_pgt + L4_PAGE_OFFSET*8, 0
633 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
634 .org init_top_pgt + L4_START_KERNEL*8, 0
635 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
636 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
637 .fill PTI_USER_PGD_FILL,8,0
638SYM_DATA_END(init_top_pgt)
639
640SYM_DATA_START_PAGE_ALIGNED(level3_ident_pgt)
641 .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
642 .fill 511, 8, 0
643SYM_DATA_END(level3_ident_pgt)
644SYM_DATA_START_PAGE_ALIGNED(level2_ident_pgt)
645 /*
646 * Since I easily can, map the first 1G.
647 * Don't set NX because code runs from these pages.
648 *
649 * Note: This sets _PAGE_GLOBAL despite whether
650 * the CPU supports it or it is enabled. But,
651 * the CPU should ignore the bit.
652 */
653 PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
654SYM_DATA_END(level2_ident_pgt)
655#else
656SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
657 .fill 512,8,0
658 .fill PTI_USER_PGD_FILL,8,0
659SYM_DATA_END(init_top_pgt)
660#endif
661
662#ifdef CONFIG_X86_5LEVEL
663SYM_DATA_START_PAGE_ALIGNED(level4_kernel_pgt)
664 .fill 511,8,0
665 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
666SYM_DATA_END(level4_kernel_pgt)
667#endif
668
669SYM_DATA_START_PAGE_ALIGNED(level3_kernel_pgt)
670 .fill L3_START_KERNEL,8,0
671 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
672 .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
673 .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
674SYM_DATA_END(level3_kernel_pgt)
675
676SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt)
677 /*
678 * Kernel high mapping.
679 *
680 * The kernel code+data+bss must be located below KERNEL_IMAGE_SIZE in
681 * virtual address space, which is 1 GiB if RANDOMIZE_BASE is enabled,
682 * 512 MiB otherwise.
683 *
684 * (NOTE: after that starts the module area, see MODULES_VADDR.)
685 *
686 * This table is eventually used by the kernel during normal runtime.
687 * Care must be taken to clear out undesired bits later, like _PAGE_RW
688 * or _PAGE_GLOBAL in some cases.
689 */
690 PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE/PMD_SIZE)
691SYM_DATA_END(level2_kernel_pgt)
692
693SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt)
694 .fill (512 - 4 - FIXMAP_PMD_NUM),8,0
695 pgtno = 0
696 .rept (FIXMAP_PMD_NUM)
697 .quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \
698 + _PAGE_TABLE_NOENC;
699 pgtno = pgtno + 1
700 .endr
701 /* 6 MB reserved space + a 2MB hole */
702 .fill 4,8,0
703SYM_DATA_END(level2_fixmap_pgt)
704
705SYM_DATA_START_PAGE_ALIGNED(level1_fixmap_pgt)
706 .rept (FIXMAP_PMD_NUM)
707 .fill 512,8,0
708 .endr
709SYM_DATA_END(level1_fixmap_pgt)
710
711#undef PMDS
712
713 .data
714 .align 16
715
716SYM_DATA(smpboot_control, .long 0)
717
718 .align 16
719/* This must match the first entry in level2_kernel_pgt */
720SYM_DATA(phys_base, .quad 0x0)
721EXPORT_SYMBOL(phys_base)
722
723#include "../../x86/xen/xen-head.S"
724
725 __PAGE_ALIGNED_BSS
726SYM_DATA_START_PAGE_ALIGNED(empty_zero_page)
727 .skip PAGE_SIZE
728SYM_DATA_END(empty_zero_page)
729EXPORT_SYMBOL(empty_zero_page)
730