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1/*
2 * linux/arch/x86/kernel/head_64.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)
41L4_START_KERNEL = pgd_index(__START_KERNEL_map)
42L3_START_KERNEL = pud_index(__START_KERNEL_map)
43
44 .text
45 __HEAD
46 .code64
47 .globl startup_64
48startup_64:
49 /*
50 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
51 * and someone has loaded an identity mapped page table
52 * for us. These identity mapped page tables map all of the
53 * kernel pages and possibly all of memory.
54 *
55 * %rsi holds a physical pointer to real_mode_data.
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
67 /* Sanitize CPU configuration */
68 call verify_cpu
69
70 /*
71 * Compute the delta between the address I am compiled to run at and the
72 * address I am actually running at.
73 */
74 leaq _text(%rip), %rbp
75 subq $_text - __START_KERNEL_map, %rbp
76
77 /* Is the address not 2M aligned? */
78 testl $~PMD_PAGE_MASK, %ebp
79 jnz bad_address
80
81 /*
82 * Is the address too large?
83 */
84 leaq _text(%rip), %rax
85 shrq $MAX_PHYSMEM_BITS, %rax
86 jnz bad_address
87
88 /*
89 * Fixup the physical addresses in the page table
90 */
91 addq %rbp, early_level4_pgt + (L4_START_KERNEL*8)(%rip)
92
93 addq %rbp, level3_kernel_pgt + (510*8)(%rip)
94 addq %rbp, level3_kernel_pgt + (511*8)(%rip)
95
96 addq %rbp, level2_fixmap_pgt + (506*8)(%rip)
97
98 /*
99 * Set up the identity mapping for the switchover. These
100 * entries should *NOT* have the global bit set! This also
101 * creates a bunch of nonsense entries but that is fine --
102 * it avoids problems around wraparound.
103 */
104 leaq _text(%rip), %rdi
105 leaq early_level4_pgt(%rip), %rbx
106
107 movq %rdi, %rax
108 shrq $PGDIR_SHIFT, %rax
109
110 leaq (4096 + _KERNPG_TABLE)(%rbx), %rdx
111 movq %rdx, 0(%rbx,%rax,8)
112 movq %rdx, 8(%rbx,%rax,8)
113
114 addq $4096, %rdx
115 movq %rdi, %rax
116 shrq $PUD_SHIFT, %rax
117 andl $(PTRS_PER_PUD-1), %eax
118 movq %rdx, 4096(%rbx,%rax,8)
119 incl %eax
120 andl $(PTRS_PER_PUD-1), %eax
121 movq %rdx, 4096(%rbx,%rax,8)
122
123 addq $8192, %rbx
124 movq %rdi, %rax
125 shrq $PMD_SHIFT, %rdi
126 addq $(__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL), %rax
127 leaq (_end - 1)(%rip), %rcx
128 shrq $PMD_SHIFT, %rcx
129 subq %rdi, %rcx
130 incl %ecx
131
1321:
133 andq $(PTRS_PER_PMD - 1), %rdi
134 movq %rax, (%rbx,%rdi,8)
135 incq %rdi
136 addq $PMD_SIZE, %rax
137 decl %ecx
138 jnz 1b
139
140 /*
141 * Fixup the kernel text+data virtual addresses. Note that
142 * we might write invalid pmds, when the kernel is relocated
143 * cleanup_highmap() fixes this up along with the mappings
144 * beyond _end.
145 */
146 leaq level2_kernel_pgt(%rip), %rdi
147 leaq 4096(%rdi), %r8
148 /* See if it is a valid page table entry */
1491: testb $1, 0(%rdi)
150 jz 2f
151 addq %rbp, 0(%rdi)
152 /* Go to the next page */
1532: addq $8, %rdi
154 cmp %r8, %rdi
155 jne 1b
156
157 /* Fixup phys_base */
158 addq %rbp, phys_base(%rip)
159
160 movq $(early_level4_pgt - __START_KERNEL_map), %rax
161 jmp 1f
162ENTRY(secondary_startup_64)
163 /*
164 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
165 * and someone has loaded a mapped page table.
166 *
167 * %rsi holds a physical pointer to real_mode_data.
168 *
169 * We come here either from startup_64 (using physical addresses)
170 * or from trampoline.S (using virtual addresses).
171 *
172 * Using virtual addresses from trampoline.S removes the need
173 * to have any identity mapped pages in the kernel page table
174 * after the boot processor executes this code.
175 */
176
177 /* Sanitize CPU configuration */
178 call verify_cpu
179
180 movq $(init_level4_pgt - __START_KERNEL_map), %rax
1811:
182
183 /* Enable PAE mode and PGE */
184 movl $(X86_CR4_PAE | X86_CR4_PGE), %ecx
185 movq %rcx, %cr4
186
187 /* Setup early boot stage 4 level pagetables. */
188 addq phys_base(%rip), %rax
189 movq %rax, %cr3
190
191 /* Ensure I am executing from virtual addresses */
192 movq $1f, %rax
193 jmp *%rax
1941:
195
196 /* Check if nx is implemented */
197 movl $0x80000001, %eax
198 cpuid
199 movl %edx,%edi
200
201 /* Setup EFER (Extended Feature Enable Register) */
202 movl $MSR_EFER, %ecx
203 rdmsr
204 btsl $_EFER_SCE, %eax /* Enable System Call */
205 btl $20,%edi /* No Execute supported? */
206 jnc 1f
207 btsl $_EFER_NX, %eax
208 btsq $_PAGE_BIT_NX,early_pmd_flags(%rip)
2091: wrmsr /* Make changes effective */
210
211 /* Setup cr0 */
212#define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \
213 X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \
214 X86_CR0_PG)
215 movl $CR0_STATE, %eax
216 /* Make changes effective */
217 movq %rax, %cr0
218
219 /* Setup a boot time stack */
220 movq stack_start(%rip), %rsp
221
222 /* zero EFLAGS after setting rsp */
223 pushq $0
224 popfq
225
226 /*
227 * We must switch to a new descriptor in kernel space for the GDT
228 * because soon the kernel won't have access anymore to the userspace
229 * addresses where we're currently running on. We have to do that here
230 * because in 32bit we couldn't load a 64bit linear address.
231 */
232 lgdt early_gdt_descr(%rip)
233
234 /* set up data segments */
235 xorl %eax,%eax
236 movl %eax,%ds
237 movl %eax,%ss
238 movl %eax,%es
239
240 /*
241 * We don't really need to load %fs or %gs, but load them anyway
242 * to kill any stale realmode selectors. This allows execution
243 * under VT hardware.
244 */
245 movl %eax,%fs
246 movl %eax,%gs
247
248 /* Set up %gs.
249 *
250 * The base of %gs always points to the bottom of the irqstack
251 * union. If the stack protector canary is enabled, it is
252 * located at %gs:40. Note that, on SMP, the boot cpu uses
253 * init data section till per cpu areas are set up.
254 */
255 movl $MSR_GS_BASE,%ecx
256 movl initial_gs(%rip),%eax
257 movl initial_gs+4(%rip),%edx
258 wrmsr
259
260 /* rsi is pointer to real mode structure with interesting info.
261 pass it to C */
262 movq %rsi, %rdi
263
264 /* Finally jump to run C code and to be on real kernel address
265 * Since we are running on identity-mapped space we have to jump
266 * to the full 64bit address, this is only possible as indirect
267 * jump. In addition we need to ensure %cs is set so we make this
268 * a far return.
269 *
270 * Note: do not change to far jump indirect with 64bit offset.
271 *
272 * AMD does not support far jump indirect with 64bit offset.
273 * AMD64 Architecture Programmer's Manual, Volume 3: states only
274 * JMP FAR mem16:16 FF /5 Far jump indirect,
275 * with the target specified by a far pointer in memory.
276 * JMP FAR mem16:32 FF /5 Far jump indirect,
277 * with the target specified by a far pointer in memory.
278 *
279 * Intel64 does support 64bit offset.
280 * Software Developer Manual Vol 2: states:
281 * FF /5 JMP m16:16 Jump far, absolute indirect,
282 * address given in m16:16
283 * FF /5 JMP m16:32 Jump far, absolute indirect,
284 * address given in m16:32.
285 * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
286 * address given in m16:64.
287 */
288 movq initial_code(%rip),%rax
289 pushq $0 # fake return address to stop unwinder
290 pushq $__KERNEL_CS # set correct cs
291 pushq %rax # target address in negative space
292 lretq
293
294#include "verify_cpu.S"
295
296#ifdef CONFIG_HOTPLUG_CPU
297/*
298 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
299 * up already except stack. We just set up stack here. Then call
300 * start_secondary().
301 */
302ENTRY(start_cpu0)
303 movq stack_start(%rip),%rsp
304 movq initial_code(%rip),%rax
305 pushq $0 # fake return address to stop unwinder
306 pushq $__KERNEL_CS # set correct cs
307 pushq %rax # target address in negative space
308 lretq
309ENDPROC(start_cpu0)
310#endif
311
312 /* SMP bootup changes these two */
313 __REFDATA
314 .balign 8
315 GLOBAL(initial_code)
316 .quad x86_64_start_kernel
317 GLOBAL(initial_gs)
318 .quad INIT_PER_CPU_VAR(irq_stack_union)
319
320 GLOBAL(stack_start)
321 .quad init_thread_union+THREAD_SIZE-8
322 .word 0
323 __FINITDATA
324
325bad_address:
326 jmp bad_address
327
328 __INIT
329ENTRY(early_idt_handler_array)
330 # 104(%rsp) %rflags
331 # 96(%rsp) %cs
332 # 88(%rsp) %rip
333 # 80(%rsp) error code
334 i = 0
335 .rept NUM_EXCEPTION_VECTORS
336 .ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1
337 pushq $0 # Dummy error code, to make stack frame uniform
338 .endif
339 pushq $i # 72(%rsp) Vector number
340 jmp early_idt_handler_common
341 i = i + 1
342 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
343 .endr
344ENDPROC(early_idt_handler_array)
345
346early_idt_handler_common:
347 /*
348 * The stack is the hardware frame, an error code or zero, and the
349 * vector number.
350 */
351 cld
352
353 cmpl $2,(%rsp) # X86_TRAP_NMI
354 je .Lis_nmi # Ignore NMI
355
356 cmpl $2,early_recursion_flag(%rip)
357 jz 1f
358 incl early_recursion_flag(%rip)
359
360 pushq %rax # 64(%rsp)
361 pushq %rcx # 56(%rsp)
362 pushq %rdx # 48(%rsp)
363 pushq %rsi # 40(%rsp)
364 pushq %rdi # 32(%rsp)
365 pushq %r8 # 24(%rsp)
366 pushq %r9 # 16(%rsp)
367 pushq %r10 # 8(%rsp)
368 pushq %r11 # 0(%rsp)
369
370 cmpl $__KERNEL_CS,96(%rsp)
371 jne 11f
372
373 cmpl $14,72(%rsp) # Page fault?
374 jnz 10f
375 GET_CR2_INTO(%rdi) # can clobber any volatile register if pv
376 call early_make_pgtable
377 andl %eax,%eax
378 jz 20f # All good
379
38010:
381 leaq 88(%rsp),%rdi # Pointer to %rip
382 call early_fixup_exception
383 andl %eax,%eax
384 jnz 20f # Found an exception entry
385
38611:
387#ifdef CONFIG_EARLY_PRINTK
388 GET_CR2_INTO(%r9) # can clobber any volatile register if pv
389 movl 80(%rsp),%r8d # error code
390 movl 72(%rsp),%esi # vector number
391 movl 96(%rsp),%edx # %cs
392 movq 88(%rsp),%rcx # %rip
393 xorl %eax,%eax
394 leaq early_idt_msg(%rip),%rdi
395 call early_printk
396 cmpl $2,early_recursion_flag(%rip)
397 jz 1f
398 call dump_stack
399#ifdef CONFIG_KALLSYMS
400 leaq early_idt_ripmsg(%rip),%rdi
401 movq 40(%rsp),%rsi # %rip again
402 call __print_symbol
403#endif
404#endif /* EARLY_PRINTK */
4051: hlt
406 jmp 1b
407
40820: # Exception table entry found or page table generated
409 popq %r11
410 popq %r10
411 popq %r9
412 popq %r8
413 popq %rdi
414 popq %rsi
415 popq %rdx
416 popq %rcx
417 popq %rax
418 decl early_recursion_flag(%rip)
419.Lis_nmi:
420 addq $16,%rsp # drop vector number and error code
421 INTERRUPT_RETURN
422ENDPROC(early_idt_handler_common)
423
424 __INITDATA
425
426 .balign 4
427early_recursion_flag:
428 .long 0
429
430#ifdef CONFIG_EARLY_PRINTK
431early_idt_msg:
432 .asciz "PANIC: early exception %02lx rip %lx:%lx error %lx cr2 %lx\n"
433early_idt_ripmsg:
434 .asciz "RIP %s\n"
435#endif /* CONFIG_EARLY_PRINTK */
436
437#define NEXT_PAGE(name) \
438 .balign PAGE_SIZE; \
439GLOBAL(name)
440
441/* Automate the creation of 1 to 1 mapping pmd entries */
442#define PMDS(START, PERM, COUNT) \
443 i = 0 ; \
444 .rept (COUNT) ; \
445 .quad (START) + (i << PMD_SHIFT) + (PERM) ; \
446 i = i + 1 ; \
447 .endr
448
449 __INITDATA
450NEXT_PAGE(early_level4_pgt)
451 .fill 511,8,0
452 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
453
454NEXT_PAGE(early_dynamic_pgts)
455 .fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
456
457 .data
458
459#ifndef CONFIG_XEN
460NEXT_PAGE(init_level4_pgt)
461 .fill 512,8,0
462#else
463NEXT_PAGE(init_level4_pgt)
464 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
465 .org init_level4_pgt + L4_PAGE_OFFSET*8, 0
466 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
467 .org init_level4_pgt + L4_START_KERNEL*8, 0
468 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
469 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
470
471NEXT_PAGE(level3_ident_pgt)
472 .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
473 .fill 511, 8, 0
474NEXT_PAGE(level2_ident_pgt)
475 /* Since I easily can, map the first 1G.
476 * Don't set NX because code runs from these pages.
477 */
478 PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
479#endif
480
481NEXT_PAGE(level3_kernel_pgt)
482 .fill L3_START_KERNEL,8,0
483 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
484 .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
485 .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
486
487NEXT_PAGE(level2_kernel_pgt)
488 /*
489 * 512 MB kernel mapping. We spend a full page on this pagetable
490 * anyway.
491 *
492 * The kernel code+data+bss must not be bigger than that.
493 *
494 * (NOTE: at +512MB starts the module area, see MODULES_VADDR.
495 * If you want to increase this then increase MODULES_VADDR
496 * too.)
497 */
498 PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
499 KERNEL_IMAGE_SIZE/PMD_SIZE)
500
501NEXT_PAGE(level2_fixmap_pgt)
502 .fill 506,8,0
503 .quad level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
504 /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
505 .fill 5,8,0
506
507NEXT_PAGE(level1_fixmap_pgt)
508 .fill 512,8,0
509
510#undef PMDS
511
512 .data
513 .align 16
514 .globl early_gdt_descr
515early_gdt_descr:
516 .word GDT_ENTRIES*8-1
517early_gdt_descr_base:
518 .quad INIT_PER_CPU_VAR(gdt_page)
519
520ENTRY(phys_base)
521 /* This must match the first entry in level2_kernel_pgt */
522 .quad 0x0000000000000000
523
524#include "../../x86/xen/xen-head.S"
525
526 __PAGE_ALIGNED_BSS
527NEXT_PAGE(empty_zero_page)
528 .skip PAGE_SIZE
529
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
30/*
31 * We are not able to switch in one step to the final KERNEL ADDRESS SPACE
32 * because we need identity-mapped pages.
33 */
34#define l4_index(x) (((x) >> 39) & 511)
35#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
36
37L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE_L4)
38L4_START_KERNEL = l4_index(__START_KERNEL_map)
39
40L3_START_KERNEL = pud_index(__START_KERNEL_map)
41
42 .text
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 - PTREGS_SIZE)(%rip), %rsp
70
71 leaq _text(%rip), %rdi
72
73 /* Setup GSBASE to allow stack canary access for C code */
74 movl $MSR_GS_BASE, %ecx
75 leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
76 movl %edx, %eax
77 shrq $32, %rdx
78 wrmsr
79
80 call startup_64_setup_env
81
82 /* Now switch to __KERNEL_CS so IRET works reliably */
83 pushq $__KERNEL_CS
84 leaq .Lon_kernel_cs(%rip), %rax
85 pushq %rax
86 lretq
87
88.Lon_kernel_cs:
89 UNWIND_HINT_END_OF_STACK
90
91#ifdef CONFIG_AMD_MEM_ENCRYPT
92 /*
93 * Activate SEV/SME memory encryption if supported/enabled. This needs to
94 * be done now, since this also includes setup of the SEV-SNP CPUID table,
95 * which needs to be done before any CPUID instructions are executed in
96 * subsequent code. Pass the boot_params pointer as the first argument.
97 */
98 movq %r15, %rdi
99 call sme_enable
100#endif
101
102 /* Sanitize CPU configuration */
103 call verify_cpu
104
105 /*
106 * Perform pagetable fixups. Additionally, if SME is active, encrypt
107 * the kernel and retrieve the modifier (SME encryption mask if SME
108 * is active) to be added to the initial pgdir entry that will be
109 * programmed into CR3.
110 */
111 leaq _text(%rip), %rdi
112 movq %r15, %rsi
113 call __startup_64
114
115 /* Form the CR3 value being sure to include the CR3 modifier */
116 addq $(early_top_pgt - __START_KERNEL_map), %rax
117
118#ifdef CONFIG_AMD_MEM_ENCRYPT
119 mov %rax, %rdi
120 mov %rax, %r14
121
122 addq phys_base(%rip), %rdi
123
124 /*
125 * For SEV guests: Verify that the C-bit is correct. A malicious
126 * hypervisor could lie about the C-bit position to perform a ROP
127 * attack on the guest by writing to the unencrypted stack and wait for
128 * the next RET instruction.
129 */
130 call sev_verify_cbit
131
132 /*
133 * Restore CR3 value without the phys_base which will be added
134 * below, before writing %cr3.
135 */
136 mov %r14, %rax
137#endif
138
139 jmp 1f
140SYM_CODE_END(startup_64)
141
142SYM_CODE_START(secondary_startup_64)
143 UNWIND_HINT_END_OF_STACK
144 ANNOTATE_NOENDBR
145 /*
146 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
147 * and someone has loaded a mapped page table.
148 *
149 * We come here either from startup_64 (using physical addresses)
150 * or from trampoline.S (using virtual addresses).
151 *
152 * Using virtual addresses from trampoline.S removes the need
153 * to have any identity mapped pages in the kernel page table
154 * after the boot processor executes this code.
155 */
156
157 /* Sanitize CPU configuration */
158 call verify_cpu
159
160 /*
161 * The secondary_startup_64_no_verify entry point is only used by
162 * SEV-ES guests. In those guests the call to verify_cpu() would cause
163 * #VC exceptions which can not be handled at this stage of secondary
164 * CPU bringup.
165 *
166 * All non SEV-ES systems, especially Intel systems, need to execute
167 * verify_cpu() above to make sure NX is enabled.
168 */
169SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
170 UNWIND_HINT_END_OF_STACK
171 ANNOTATE_NOENDBR
172
173 /* Clear %R15 which holds the boot_params pointer on the boot CPU */
174 xorq %r15, %r15
175
176 /*
177 * Retrieve the modifier (SME encryption mask if SME is active) to be
178 * added to the initial pgdir entry that will be programmed into CR3.
179 */
180#ifdef CONFIG_AMD_MEM_ENCRYPT
181 movq sme_me_mask, %rax
182#else
183 xorq %rax, %rax
184#endif
185
186 /* Form the CR3 value being sure to include the CR3 modifier */
187 addq $(init_top_pgt - __START_KERNEL_map), %rax
1881:
189
190#ifdef CONFIG_X86_MCE
191 /*
192 * Preserve CR4.MCE if the kernel will enable #MC support.
193 * Clearing MCE may fault in some environments (that also force #MC
194 * support). Any machine check that occurs before #MC support is fully
195 * configured will crash the system regardless of the CR4.MCE value set
196 * here.
197 */
198 movq %cr4, %rcx
199 andl $X86_CR4_MCE, %ecx
200#else
201 movl $0, %ecx
202#endif
203
204 /* Enable PAE mode, PSE, PGE and LA57 */
205 orl $(X86_CR4_PAE | X86_CR4_PSE | X86_CR4_PGE), %ecx
206#ifdef CONFIG_X86_5LEVEL
207 testb $1, __pgtable_l5_enabled(%rip)
208 jz 1f
209 orl $X86_CR4_LA57, %ecx
2101:
211#endif
212 movq %rcx, %cr4
213
214 /* Setup early boot stage 4-/5-level pagetables. */
215 addq phys_base(%rip), %rax
216
217 /*
218 * Switch to new page-table
219 *
220 * For the boot CPU this switches to early_top_pgt which still has the
221 * identity mappings present. The secondary CPUs will switch to the
222 * init_top_pgt here, away from the trampoline_pgd and unmap the
223 * identity mapped ranges.
224 */
225 movq %rax, %cr3
226
227 /*
228 * Do a global TLB flush after the CR3 switch to make sure the TLB
229 * entries from the identity mapping are flushed.
230 */
231 movq %cr4, %rcx
232 movq %rcx, %rax
233 xorq $X86_CR4_PGE, %rcx
234 movq %rcx, %cr4
235 movq %rax, %cr4
236
237 /* Ensure I am executing from virtual addresses */
238 movq $1f, %rax
239 ANNOTATE_RETPOLINE_SAFE
240 jmp *%rax
2411:
242 UNWIND_HINT_END_OF_STACK
243 ANNOTATE_NOENDBR // above
244
245#ifdef CONFIG_SMP
246 /*
247 * For parallel boot, the APIC ID is read from the APIC, and then
248 * used to look up the CPU number. For booting a single CPU, the
249 * CPU number is encoded in smpboot_control.
250 *
251 * Bit 31 STARTUP_READ_APICID (Read APICID from APIC)
252 * Bit 0-23 CPU# if STARTUP_xx flags are not set
253 */
254 movl smpboot_control(%rip), %ecx
255 testl $STARTUP_READ_APICID, %ecx
256 jnz .Lread_apicid
257 /*
258 * No control bit set, single CPU bringup. CPU number is provided
259 * in bit 0-23. This is also the boot CPU case (CPU number 0).
260 */
261 andl $(~STARTUP_PARALLEL_MASK), %ecx
262 jmp .Lsetup_cpu
263
264.Lread_apicid:
265 /* Check whether X2APIC mode is already enabled */
266 mov $MSR_IA32_APICBASE, %ecx
267 rdmsr
268 testl $X2APIC_ENABLE, %eax
269 jnz .Lread_apicid_msr
270
271#ifdef CONFIG_X86_X2APIC
272 /*
273 * If system is in X2APIC mode then MMIO base might not be
274 * mapped causing the MMIO read below to fault. Faults can't
275 * be handled at that point.
276 */
277 cmpl $0, x2apic_mode(%rip)
278 jz .Lread_apicid_mmio
279
280 /* Force the AP into X2APIC mode. */
281 orl $X2APIC_ENABLE, %eax
282 wrmsr
283 jmp .Lread_apicid_msr
284#endif
285
286.Lread_apicid_mmio:
287 /* Read the APIC ID from the fix-mapped MMIO space. */
288 movq apic_mmio_base(%rip), %rcx
289 addq $APIC_ID, %rcx
290 movl (%rcx), %eax
291 shr $24, %eax
292 jmp .Llookup_AP
293
294.Lread_apicid_msr:
295 mov $APIC_X2APIC_ID_MSR, %ecx
296 rdmsr
297
298.Llookup_AP:
299 /* EAX contains the APIC ID of the current CPU */
300 xorq %rcx, %rcx
301 leaq cpuid_to_apicid(%rip), %rbx
302
303.Lfind_cpunr:
304 cmpl (%rbx,%rcx,4), %eax
305 jz .Lsetup_cpu
306 inc %ecx
307#ifdef CONFIG_FORCE_NR_CPUS
308 cmpl $NR_CPUS, %ecx
309#else
310 cmpl nr_cpu_ids(%rip), %ecx
311#endif
312 jb .Lfind_cpunr
313
314 /* APIC ID not found in the table. Drop the trampoline lock and bail. */
315 movq trampoline_lock(%rip), %rax
316 movl $0, (%rax)
317
3181: cli
319 hlt
320 jmp 1b
321
322.Lsetup_cpu:
323 /* Get the per cpu offset for the given CPU# which is in ECX */
324 movq __per_cpu_offset(,%rcx,8), %rdx
325#else
326 xorl %edx, %edx /* zero-extended to clear all of RDX */
327#endif /* CONFIG_SMP */
328
329 /*
330 * Setup a boot time stack - Any secondary CPU will have lost its stack
331 * by now because the cr3-switch above unmaps the real-mode stack.
332 *
333 * RDX contains the per-cpu offset
334 */
335 movq pcpu_hot + X86_current_task(%rdx), %rax
336 movq TASK_threadsp(%rax), %rsp
337
338 /*
339 * Now that this CPU is running on its own stack, drop the realmode
340 * protection. For the boot CPU the pointer is NULL!
341 */
342 movq trampoline_lock(%rip), %rax
343 testq %rax, %rax
344 jz .Lsetup_gdt
345 movl $0, (%rax)
346
347.Lsetup_gdt:
348 /*
349 * We must switch to a new descriptor in kernel space for the GDT
350 * because soon the kernel won't have access anymore to the userspace
351 * addresses where we're currently running on. We have to do that here
352 * because in 32bit we couldn't load a 64bit linear address.
353 */
354 subq $16, %rsp
355 movw $(GDT_SIZE-1), (%rsp)
356 leaq gdt_page(%rdx), %rax
357 movq %rax, 2(%rsp)
358 lgdt (%rsp)
359 addq $16, %rsp
360
361 /* set up data segments */
362 xorl %eax,%eax
363 movl %eax,%ds
364 movl %eax,%ss
365 movl %eax,%es
366
367 /*
368 * We don't really need to load %fs or %gs, but load them anyway
369 * to kill any stale realmode selectors. This allows execution
370 * under VT hardware.
371 */
372 movl %eax,%fs
373 movl %eax,%gs
374
375 /* Set up %gs.
376 *
377 * The base of %gs always points to fixed_percpu_data. If the
378 * stack protector canary is enabled, it is located at %gs:40.
379 * Note that, on SMP, the boot cpu uses init data section until
380 * the per cpu areas are set up.
381 */
382 movl $MSR_GS_BASE,%ecx
383#ifndef CONFIG_SMP
384 leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
385#endif
386 movl %edx, %eax
387 shrq $32, %rdx
388 wrmsr
389
390 /* Setup and Load IDT */
391 call early_setup_idt
392
393 /* Check if nx is implemented */
394 movl $0x80000001, %eax
395 cpuid
396 movl %edx,%edi
397
398 /* Setup EFER (Extended Feature Enable Register) */
399 movl $MSR_EFER, %ecx
400 rdmsr
401 /*
402 * Preserve current value of EFER for comparison and to skip
403 * EFER writes if no change was made (for TDX guest)
404 */
405 movl %eax, %edx
406 btsl $_EFER_SCE, %eax /* Enable System Call */
407 btl $20,%edi /* No Execute supported? */
408 jnc 1f
409 btsl $_EFER_NX, %eax
410 btsq $_PAGE_BIT_NX,early_pmd_flags(%rip)
411
412 /* Avoid writing EFER if no change was made (for TDX guest) */
4131: cmpl %edx, %eax
414 je 1f
415 xor %edx, %edx
416 wrmsr /* Make changes effective */
4171:
418 /* Setup cr0 */
419 movl $CR0_STATE, %eax
420 /* Make changes effective */
421 movq %rax, %cr0
422
423 /* zero EFLAGS after setting rsp */
424 pushq $0
425 popfq
426
427 /* Pass the boot_params pointer as first argument */
428 movq %r15, %rdi
429
430.Ljump_to_C_code:
431 /*
432 * Jump to run C code and to be on a real kernel address.
433 * Since we are running on identity-mapped space we have to jump
434 * to the full 64bit address, this is only possible as indirect
435 * jump. In addition we need to ensure %cs is set so we make this
436 * a far return.
437 *
438 * Note: do not change to far jump indirect with 64bit offset.
439 *
440 * AMD does not support far jump indirect with 64bit offset.
441 * AMD64 Architecture Programmer's Manual, Volume 3: states only
442 * JMP FAR mem16:16 FF /5 Far jump indirect,
443 * with the target specified by a far pointer in memory.
444 * JMP FAR mem16:32 FF /5 Far jump indirect,
445 * with the target specified by a far pointer in memory.
446 *
447 * Intel64 does support 64bit offset.
448 * Software Developer Manual Vol 2: states:
449 * FF /5 JMP m16:16 Jump far, absolute indirect,
450 * address given in m16:16
451 * FF /5 JMP m16:32 Jump far, absolute indirect,
452 * address given in m16:32.
453 * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
454 * address given in m16:64.
455 */
456 pushq $.Lafter_lret # put return address on stack for unwinder
457 xorl %ebp, %ebp # clear frame pointer
458 movq initial_code(%rip), %rax
459 pushq $__KERNEL_CS # set correct cs
460 pushq %rax # target address in negative space
461 lretq
462.Lafter_lret:
463 ANNOTATE_NOENDBR
464SYM_CODE_END(secondary_startup_64)
465
466#include "verify_cpu.S"
467#include "sev_verify_cbit.S"
468
469#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_AMD_MEM_ENCRYPT)
470/*
471 * Entry point for soft restart of a CPU. Invoked from xxx_play_dead() for
472 * restarting the boot CPU or for restarting SEV guest CPUs after CPU hot
473 * unplug. Everything is set up already except the stack.
474 */
475SYM_CODE_START(soft_restart_cpu)
476 ANNOTATE_NOENDBR
477 UNWIND_HINT_END_OF_STACK
478
479 /* Find the idle task stack */
480 movq PER_CPU_VAR(pcpu_hot) + X86_current_task, %rcx
481 movq TASK_threadsp(%rcx), %rsp
482
483 jmp .Ljump_to_C_code
484SYM_CODE_END(soft_restart_cpu)
485#endif
486
487#ifdef CONFIG_AMD_MEM_ENCRYPT
488/*
489 * VC Exception handler used during early boot when running on kernel
490 * addresses, but before the switch to the idt_table can be made.
491 * The early_idt_handler_array can't be used here because it calls into a lot
492 * of __init code and this handler is also used during CPU offlining/onlining.
493 * Therefore this handler ends up in the .text section so that it stays around
494 * when .init.text is freed.
495 */
496SYM_CODE_START_NOALIGN(vc_boot_ghcb)
497 UNWIND_HINT_IRET_REGS offset=8
498 ENDBR
499
500 /* Build pt_regs */
501 PUSH_AND_CLEAR_REGS
502
503 /* Call C handler */
504 movq %rsp, %rdi
505 movq ORIG_RAX(%rsp), %rsi
506 movq initial_vc_handler(%rip), %rax
507 ANNOTATE_RETPOLINE_SAFE
508 call *%rax
509
510 /* Unwind pt_regs */
511 POP_REGS
512
513 /* Remove Error Code */
514 addq $8, %rsp
515
516 iretq
517SYM_CODE_END(vc_boot_ghcb)
518#endif
519
520 /* Both SMP bootup and ACPI suspend change these variables */
521 __REFDATA
522 .balign 8
523SYM_DATA(initial_code, .quad x86_64_start_kernel)
524#ifdef CONFIG_AMD_MEM_ENCRYPT
525SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb)
526#endif
527
528SYM_DATA(trampoline_lock, .quad 0);
529 __FINITDATA
530
531 __INIT
532SYM_CODE_START(early_idt_handler_array)
533 i = 0
534 .rept NUM_EXCEPTION_VECTORS
535 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
536 UNWIND_HINT_IRET_REGS
537 ENDBR
538 pushq $0 # Dummy error code, to make stack frame uniform
539 .else
540 UNWIND_HINT_IRET_REGS offset=8
541 ENDBR
542 .endif
543 pushq $i # 72(%rsp) Vector number
544 jmp early_idt_handler_common
545 UNWIND_HINT_IRET_REGS
546 i = i + 1
547 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
548 .endr
549SYM_CODE_END(early_idt_handler_array)
550 ANNOTATE_NOENDBR // early_idt_handler_array[NUM_EXCEPTION_VECTORS]
551
552SYM_CODE_START_LOCAL(early_idt_handler_common)
553 UNWIND_HINT_IRET_REGS offset=16
554 /*
555 * The stack is the hardware frame, an error code or zero, and the
556 * vector number.
557 */
558 cld
559
560 incl early_recursion_flag(%rip)
561
562 /* The vector number is currently in the pt_regs->di slot. */
563 pushq %rsi /* pt_regs->si */
564 movq 8(%rsp), %rsi /* RSI = vector number */
565 movq %rdi, 8(%rsp) /* pt_regs->di = RDI */
566 pushq %rdx /* pt_regs->dx */
567 pushq %rcx /* pt_regs->cx */
568 pushq %rax /* pt_regs->ax */
569 pushq %r8 /* pt_regs->r8 */
570 pushq %r9 /* pt_regs->r9 */
571 pushq %r10 /* pt_regs->r10 */
572 pushq %r11 /* pt_regs->r11 */
573 pushq %rbx /* pt_regs->bx */
574 pushq %rbp /* pt_regs->bp */
575 pushq %r12 /* pt_regs->r12 */
576 pushq %r13 /* pt_regs->r13 */
577 pushq %r14 /* pt_regs->r14 */
578 pushq %r15 /* pt_regs->r15 */
579 UNWIND_HINT_REGS
580
581 movq %rsp,%rdi /* RDI = pt_regs; RSI is already trapnr */
582 call do_early_exception
583
584 decl early_recursion_flag(%rip)
585 jmp restore_regs_and_return_to_kernel
586SYM_CODE_END(early_idt_handler_common)
587
588#ifdef CONFIG_AMD_MEM_ENCRYPT
589/*
590 * VC Exception handler used during very early boot. The
591 * early_idt_handler_array can't be used because it returns via the
592 * paravirtualized INTERRUPT_RETURN and pv-ops don't work that early.
593 *
594 * XXX it does, fix this.
595 *
596 * This handler will end up in the .init.text section and not be
597 * available to boot secondary CPUs.
598 */
599SYM_CODE_START_NOALIGN(vc_no_ghcb)
600 UNWIND_HINT_IRET_REGS offset=8
601 ENDBR
602
603 /* Build pt_regs */
604 PUSH_AND_CLEAR_REGS
605
606 /* Call C handler */
607 movq %rsp, %rdi
608 movq ORIG_RAX(%rsp), %rsi
609 call do_vc_no_ghcb
610
611 /* Unwind pt_regs */
612 POP_REGS
613
614 /* Remove Error Code */
615 addq $8, %rsp
616
617 /* Pure iret required here - don't use INTERRUPT_RETURN */
618 iretq
619SYM_CODE_END(vc_no_ghcb)
620#endif
621
622#define SYM_DATA_START_PAGE_ALIGNED(name) \
623 SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE)
624
625#ifdef CONFIG_PAGE_TABLE_ISOLATION
626/*
627 * Each PGD needs to be 8k long and 8k aligned. We do not
628 * ever go out to userspace with these, so we do not
629 * strictly *need* the second page, but this allows us to
630 * have a single set_pgd() implementation that does not
631 * need to worry about whether it has 4k or 8k to work
632 * with.
633 *
634 * This ensures PGDs are 8k long:
635 */
636#define PTI_USER_PGD_FILL 512
637/* This ensures they are 8k-aligned: */
638#define SYM_DATA_START_PTI_ALIGNED(name) \
639 SYM_START(name, SYM_L_GLOBAL, .balign 2 * PAGE_SIZE)
640#else
641#define SYM_DATA_START_PTI_ALIGNED(name) \
642 SYM_DATA_START_PAGE_ALIGNED(name)
643#define PTI_USER_PGD_FILL 0
644#endif
645
646/* Automate the creation of 1 to 1 mapping pmd entries */
647#define PMDS(START, PERM, COUNT) \
648 i = 0 ; \
649 .rept (COUNT) ; \
650 .quad (START) + (i << PMD_SHIFT) + (PERM) ; \
651 i = i + 1 ; \
652 .endr
653
654 __INITDATA
655 .balign 4
656
657SYM_DATA_START_PTI_ALIGNED(early_top_pgt)
658 .fill 512,8,0
659 .fill PTI_USER_PGD_FILL,8,0
660SYM_DATA_END(early_top_pgt)
661
662SYM_DATA_START_PAGE_ALIGNED(early_dynamic_pgts)
663 .fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
664SYM_DATA_END(early_dynamic_pgts)
665
666SYM_DATA(early_recursion_flag, .long 0)
667
668 .data
669
670#if defined(CONFIG_XEN_PV) || defined(CONFIG_PVH)
671SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
672 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
673 .org init_top_pgt + L4_PAGE_OFFSET*8, 0
674 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
675 .org init_top_pgt + L4_START_KERNEL*8, 0
676 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
677 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
678 .fill PTI_USER_PGD_FILL,8,0
679SYM_DATA_END(init_top_pgt)
680
681SYM_DATA_START_PAGE_ALIGNED(level3_ident_pgt)
682 .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
683 .fill 511, 8, 0
684SYM_DATA_END(level3_ident_pgt)
685SYM_DATA_START_PAGE_ALIGNED(level2_ident_pgt)
686 /*
687 * Since I easily can, map the first 1G.
688 * Don't set NX because code runs from these pages.
689 *
690 * Note: This sets _PAGE_GLOBAL despite whether
691 * the CPU supports it or it is enabled. But,
692 * the CPU should ignore the bit.
693 */
694 PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
695SYM_DATA_END(level2_ident_pgt)
696#else
697SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
698 .fill 512,8,0
699 .fill PTI_USER_PGD_FILL,8,0
700SYM_DATA_END(init_top_pgt)
701#endif
702
703#ifdef CONFIG_X86_5LEVEL
704SYM_DATA_START_PAGE_ALIGNED(level4_kernel_pgt)
705 .fill 511,8,0
706 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
707SYM_DATA_END(level4_kernel_pgt)
708#endif
709
710SYM_DATA_START_PAGE_ALIGNED(level3_kernel_pgt)
711 .fill L3_START_KERNEL,8,0
712 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
713 .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
714 .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
715SYM_DATA_END(level3_kernel_pgt)
716
717SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt)
718 /*
719 * Kernel high mapping.
720 *
721 * The kernel code+data+bss must be located below KERNEL_IMAGE_SIZE in
722 * virtual address space, which is 1 GiB if RANDOMIZE_BASE is enabled,
723 * 512 MiB otherwise.
724 *
725 * (NOTE: after that starts the module area, see MODULES_VADDR.)
726 *
727 * This table is eventually used by the kernel during normal runtime.
728 * Care must be taken to clear out undesired bits later, like _PAGE_RW
729 * or _PAGE_GLOBAL in some cases.
730 */
731 PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE/PMD_SIZE)
732SYM_DATA_END(level2_kernel_pgt)
733
734SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt)
735 .fill (512 - 4 - FIXMAP_PMD_NUM),8,0
736 pgtno = 0
737 .rept (FIXMAP_PMD_NUM)
738 .quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \
739 + _PAGE_TABLE_NOENC;
740 pgtno = pgtno + 1
741 .endr
742 /* 6 MB reserved space + a 2MB hole */
743 .fill 4,8,0
744SYM_DATA_END(level2_fixmap_pgt)
745
746SYM_DATA_START_PAGE_ALIGNED(level1_fixmap_pgt)
747 .rept (FIXMAP_PMD_NUM)
748 .fill 512,8,0
749 .endr
750SYM_DATA_END(level1_fixmap_pgt)
751
752#undef PMDS
753
754 .data
755 .align 16
756
757SYM_DATA(smpboot_control, .long 0)
758
759 .align 16
760/* This must match the first entry in level2_kernel_pgt */
761SYM_DATA(phys_base, .quad 0x0)
762EXPORT_SYMBOL(phys_base)
763
764#include "../../x86/xen/xen-head.S"
765
766 __PAGE_ALIGNED_BSS
767SYM_DATA_START_PAGE_ALIGNED(empty_zero_page)
768 .skip PAGE_SIZE
769SYM_DATA_END(empty_zero_page)
770EXPORT_SYMBOL(empty_zero_page)
771