1 /* SPDX-License-Identifier: GPL-2.0 */
3 * linux/arch/x86/kernel/head_64.S -- start in 32bit and switch to 64bit
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>
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>
20 #include <asm/cache.h>
21 #include <asm/processor-flags.h>
22 #include <asm/percpu.h>
24 #include "../entry/calling.h"
25 #include <asm/export.h>
26 #include <asm/nospec-branch.h>
27 #include <asm/fixmap.h>
29 #ifdef CONFIG_PARAVIRT_XXL
30 #include <asm/asm-offsets.h>
31 #include <asm/paravirt.h>
32 #define GET_CR2_INTO(reg) GET_CR2_INTO_AX ; _ASM_MOV %_ASM_AX, reg
34 #define INTERRUPT_RETURN iretq
35 #define GET_CR2_INTO(reg) _ASM_MOV %cr2, reg
39 * We are not able to switch in one step to the final KERNEL ADDRESS SPACE
40 * because we need identity-mapped pages.
42 #define l4_index(x) (((x) >> 39) & 511)
43 #define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
45 L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE_L4)
46 L4_START_KERNEL = l4_index(__START_KERNEL_map)
48 L3_START_KERNEL = pud_index(__START_KERNEL_map)
53 SYM_CODE_START_NOALIGN(startup_64)
56 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
57 * and someone has loaded an identity mapped page table
58 * for us. These identity mapped page tables map all of the
59 * kernel pages and possibly all of memory.
61 * %rsi holds a physical pointer to real_mode_data.
63 * We come here either directly from a 64bit bootloader, or from
64 * arch/x86/boot/compressed/head_64.S.
66 * We only come here initially at boot nothing else comes here.
68 * Since we may be loaded at an address different from what we were
69 * compiled to run at we first fixup the physical addresses in our page
70 * tables and then reload them.
73 /* Set up the stack for verify_cpu(), similar to initial_stack below */
74 leaq (__end_init_task - SIZEOF_PTREGS)(%rip), %rsp
76 leaq _text(%rip), %rdi
78 call startup_64_setup_env
81 /* Now switch to __KERNEL_CS so IRET works reliably */
83 leaq .Lon_kernel_cs(%rip), %rax
90 /* Sanitize CPU configuration */
94 * Perform pagetable fixups. Additionally, if SME is active, encrypt
95 * the kernel and retrieve the modifier (SME encryption mask if SME
96 * is active) to be added to the initial pgdir entry that will be
97 * programmed into CR3.
99 leaq _text(%rip), %rdi
104 /* Form the CR3 value being sure to include the CR3 modifier */
105 addq $(early_top_pgt - __START_KERNEL_map), %rax
107 SYM_CODE_END(startup_64)
109 SYM_CODE_START(secondary_startup_64)
112 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
113 * and someone has loaded a mapped page table.
115 * %rsi holds a physical pointer to real_mode_data.
117 * We come here either from startup_64 (using physical addresses)
118 * or from trampoline.S (using virtual addresses).
120 * Using virtual addresses from trampoline.S removes the need
121 * to have any identity mapped pages in the kernel page table
122 * after the boot processor executes this code.
125 /* Sanitize CPU configuration */
129 * The secondary_startup_64_no_verify entry point is only used by
130 * SEV-ES guests. In those guests the call to verify_cpu() would cause
131 * #VC exceptions which can not be handled at this stage of secondary
134 * All non SEV-ES systems, especially Intel systems, need to execute
135 * verify_cpu() above to make sure NX is enabled.
137 SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
141 * Retrieve the modifier (SME encryption mask if SME is active) to be
142 * added to the initial pgdir entry that will be programmed into CR3.
145 call __startup_secondary_64
148 /* Form the CR3 value being sure to include the CR3 modifier */
149 addq $(init_top_pgt - __START_KERNEL_map), %rax
152 /* Enable PAE mode, PGE and LA57 */
153 movl $(X86_CR4_PAE | X86_CR4_PGE), %ecx
154 #ifdef CONFIG_X86_5LEVEL
155 testl $1, __pgtable_l5_enabled(%rip)
157 orl $X86_CR4_LA57, %ecx
162 /* Setup early boot stage 4-/5-level pagetables. */
163 addq phys_base(%rip), %rax
166 * For SEV guests: Verify that the C-bit is correct. A malicious
167 * hypervisor could lie about the C-bit position to perform a ROP
168 * attack on the guest by writing to the unencrypted stack and wait for
169 * the next RET instruction.
170 * %rsi carries pointer to realmode data and is callee-clobbered. Save
178 /* Switch to new page-table */
181 /* Ensure I am executing from virtual addresses */
183 ANNOTATE_RETPOLINE_SAFE
189 * We must switch to a new descriptor in kernel space for the GDT
190 * because soon the kernel won't have access anymore to the userspace
191 * addresses where we're currently running on. We have to do that here
192 * because in 32bit we couldn't load a 64bit linear address.
194 lgdt early_gdt_descr(%rip)
196 /* set up data segments */
203 * We don't really need to load %fs or %gs, but load them anyway
204 * to kill any stale realmode selectors. This allows execution
212 * The base of %gs always points to fixed_percpu_data. If the
213 * stack protector canary is enabled, it is located at %gs:40.
214 * Note that, on SMP, the boot cpu uses init data section until
215 * the per cpu areas are set up.
217 movl $MSR_GS_BASE,%ecx
218 movl initial_gs(%rip),%eax
219 movl initial_gs+4(%rip),%edx
223 * Setup a boot time stack - Any secondary CPU will have lost its stack
224 * by now because the cr3-switch above unmaps the real-mode stack
226 movq initial_stack(%rip), %rsp
228 /* Setup and Load IDT */
233 /* Check if nx is implemented */
234 movl $0x80000001, %eax
238 /* Setup EFER (Extended Feature Enable Register) */
241 btsl $_EFER_SCE, %eax /* Enable System Call */
242 btl $20,%edi /* No Execute supported? */
245 btsq $_PAGE_BIT_NX,early_pmd_flags(%rip)
246 1: wrmsr /* Make changes effective */
249 movl $CR0_STATE, %eax
250 /* Make changes effective */
253 /* zero EFLAGS after setting rsp */
257 /* rsi is pointer to real mode structure with interesting info.
263 * Jump to run C code and to be on a real kernel address.
264 * Since we are running on identity-mapped space we have to jump
265 * to the full 64bit address, this is only possible as indirect
266 * jump. In addition we need to ensure %cs is set so we make this
269 * Note: do not change to far jump indirect with 64bit offset.
271 * AMD does not support far jump indirect with 64bit offset.
272 * AMD64 Architecture Programmer's Manual, Volume 3: states only
273 * JMP FAR mem16:16 FF /5 Far jump indirect,
274 * with the target specified by a far pointer in memory.
275 * JMP FAR mem16:32 FF /5 Far jump indirect,
276 * with the target specified by a far pointer in memory.
278 * Intel64 does support 64bit offset.
279 * Software Developer Manual Vol 2: states:
280 * FF /5 JMP m16:16 Jump far, absolute indirect,
281 * address given in m16:16
282 * FF /5 JMP m16:32 Jump far, absolute indirect,
283 * address given in m16:32.
284 * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
285 * address given in m16:64.
287 pushq $.Lafter_lret # put return address on stack for unwinder
288 xorl %ebp, %ebp # clear frame pointer
289 movq initial_code(%rip), %rax
290 pushq $__KERNEL_CS # set correct cs
291 pushq %rax # target address in negative space
294 SYM_CODE_END(secondary_startup_64)
296 #include "verify_cpu.S"
297 #include "sev_verify_cbit.S"
299 #ifdef CONFIG_HOTPLUG_CPU
301 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
302 * up already except stack. We just set up stack here. Then call
303 * start_secondary() via .Ljump_to_C_code.
305 SYM_CODE_START(start_cpu0)
307 movq initial_stack(%rip), %rsp
309 SYM_CODE_END(start_cpu0)
312 #ifdef CONFIG_AMD_MEM_ENCRYPT
314 * VC Exception handler used during early boot when running on kernel
315 * addresses, but before the switch to the idt_table can be made.
316 * The early_idt_handler_array can't be used here because it calls into a lot
317 * of __init code and this handler is also used during CPU offlining/onlining.
318 * Therefore this handler ends up in the .text section so that it stays around
319 * when .init.text is freed.
321 SYM_CODE_START_NOALIGN(vc_boot_ghcb)
322 UNWIND_HINT_IRET_REGS offset=8
329 movq ORIG_RAX(%rsp), %rsi
330 movq initial_vc_handler(%rip), %rax
331 ANNOTATE_RETPOLINE_SAFE
337 /* Remove Error Code */
340 /* Pure iret required here - don't use INTERRUPT_RETURN */
342 SYM_CODE_END(vc_boot_ghcb)
345 /* Both SMP bootup and ACPI suspend change these variables */
348 SYM_DATA(initial_code, .quad x86_64_start_kernel)
349 SYM_DATA(initial_gs, .quad INIT_PER_CPU_VAR(fixed_percpu_data))
350 #ifdef CONFIG_AMD_MEM_ENCRYPT
351 SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb)
355 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder
356 * reliably detect the end of the stack.
358 SYM_DATA(initial_stack, .quad init_thread_union + THREAD_SIZE - SIZEOF_PTREGS)
362 SYM_CODE_START(early_idt_handler_array)
364 .rept NUM_EXCEPTION_VECTORS
365 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
366 UNWIND_HINT_IRET_REGS
367 pushq $0 # Dummy error code, to make stack frame uniform
369 UNWIND_HINT_IRET_REGS offset=8
371 pushq $i # 72(%rsp) Vector number
372 jmp early_idt_handler_common
373 UNWIND_HINT_IRET_REGS
375 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
377 UNWIND_HINT_IRET_REGS offset=16
378 SYM_CODE_END(early_idt_handler_array)
380 SYM_CODE_START_LOCAL(early_idt_handler_common)
382 * The stack is the hardware frame, an error code or zero, and the
387 incl early_recursion_flag(%rip)
389 /* The vector number is currently in the pt_regs->di slot. */
390 pushq %rsi /* pt_regs->si */
391 movq 8(%rsp), %rsi /* RSI = vector number */
392 movq %rdi, 8(%rsp) /* pt_regs->di = RDI */
393 pushq %rdx /* pt_regs->dx */
394 pushq %rcx /* pt_regs->cx */
395 pushq %rax /* pt_regs->ax */
396 pushq %r8 /* pt_regs->r8 */
397 pushq %r9 /* pt_regs->r9 */
398 pushq %r10 /* pt_regs->r10 */
399 pushq %r11 /* pt_regs->r11 */
400 pushq %rbx /* pt_regs->bx */
401 pushq %rbp /* pt_regs->bp */
402 pushq %r12 /* pt_regs->r12 */
403 pushq %r13 /* pt_regs->r13 */
404 pushq %r14 /* pt_regs->r14 */
405 pushq %r15 /* pt_regs->r15 */
408 movq %rsp,%rdi /* RDI = pt_regs; RSI is already trapnr */
409 call do_early_exception
411 decl early_recursion_flag(%rip)
412 jmp restore_regs_and_return_to_kernel
413 SYM_CODE_END(early_idt_handler_common)
415 #ifdef CONFIG_AMD_MEM_ENCRYPT
417 * VC Exception handler used during very early boot. The
418 * early_idt_handler_array can't be used because it returns via the
419 * paravirtualized INTERRUPT_RETURN and pv-ops don't work that early.
421 * This handler will end up in the .init.text section and not be
422 * available to boot secondary CPUs.
424 SYM_CODE_START_NOALIGN(vc_no_ghcb)
425 UNWIND_HINT_IRET_REGS offset=8
432 movq ORIG_RAX(%rsp), %rsi
438 /* Remove Error Code */
441 /* Pure iret required here - don't use INTERRUPT_RETURN */
443 SYM_CODE_END(vc_no_ghcb)
446 #define SYM_DATA_START_PAGE_ALIGNED(name) \
447 SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE)
449 #ifdef CONFIG_PAGE_TABLE_ISOLATION
451 * Each PGD needs to be 8k long and 8k aligned. We do not
452 * ever go out to userspace with these, so we do not
453 * strictly *need* the second page, but this allows us to
454 * have a single set_pgd() implementation that does not
455 * need to worry about whether it has 4k or 8k to work
458 * This ensures PGDs are 8k long:
460 #define PTI_USER_PGD_FILL 512
461 /* This ensures they are 8k-aligned: */
462 #define SYM_DATA_START_PTI_ALIGNED(name) \
463 SYM_START(name, SYM_L_GLOBAL, .balign 2 * PAGE_SIZE)
465 #define SYM_DATA_START_PTI_ALIGNED(name) \
466 SYM_DATA_START_PAGE_ALIGNED(name)
467 #define PTI_USER_PGD_FILL 0
470 /* Automate the creation of 1 to 1 mapping pmd entries */
471 #define PMDS(START, PERM, COUNT) \
474 .quad (START) + (i << PMD_SHIFT) + (PERM) ; \
481 SYM_DATA_START_PTI_ALIGNED(early_top_pgt)
483 .fill PTI_USER_PGD_FILL,8,0
484 SYM_DATA_END(early_top_pgt)
486 SYM_DATA_START_PAGE_ALIGNED(early_dynamic_pgts)
487 .fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
488 SYM_DATA_END(early_dynamic_pgts)
490 SYM_DATA(early_recursion_flag, .long 0)
494 #if defined(CONFIG_XEN_PV) || defined(CONFIG_PVH)
495 SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
496 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
497 .org init_top_pgt + L4_PAGE_OFFSET*8, 0
498 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
499 .org init_top_pgt + L4_START_KERNEL*8, 0
500 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
501 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
502 .fill PTI_USER_PGD_FILL,8,0
503 SYM_DATA_END(init_top_pgt)
505 SYM_DATA_START_PAGE_ALIGNED(level3_ident_pgt)
506 .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
508 SYM_DATA_END(level3_ident_pgt)
509 SYM_DATA_START_PAGE_ALIGNED(level2_ident_pgt)
511 * Since I easily can, map the first 1G.
512 * Don't set NX because code runs from these pages.
514 * Note: This sets _PAGE_GLOBAL despite whether
515 * the CPU supports it or it is enabled. But,
516 * the CPU should ignore the bit.
518 PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
519 SYM_DATA_END(level2_ident_pgt)
521 SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
523 .fill PTI_USER_PGD_FILL,8,0
524 SYM_DATA_END(init_top_pgt)
527 #ifdef CONFIG_X86_5LEVEL
528 SYM_DATA_START_PAGE_ALIGNED(level4_kernel_pgt)
530 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
531 SYM_DATA_END(level4_kernel_pgt)
534 SYM_DATA_START_PAGE_ALIGNED(level3_kernel_pgt)
535 .fill L3_START_KERNEL,8,0
536 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
537 .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
538 .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
539 SYM_DATA_END(level3_kernel_pgt)
541 SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt)
543 * 512 MB kernel mapping. We spend a full page on this pagetable
546 * The kernel code+data+bss must not be bigger than that.
548 * (NOTE: at +512MB starts the module area, see MODULES_VADDR.
549 * If you want to increase this then increase MODULES_VADDR
552 * This table is eventually used by the kernel during normal
553 * runtime. Care must be taken to clear out undesired bits
554 * later, like _PAGE_RW or _PAGE_GLOBAL in some cases.
556 PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
557 KERNEL_IMAGE_SIZE/PMD_SIZE)
558 SYM_DATA_END(level2_kernel_pgt)
560 SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt)
561 .fill (512 - 4 - FIXMAP_PMD_NUM),8,0
563 .rept (FIXMAP_PMD_NUM)
564 .quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \
568 /* 6 MB reserved space + a 2MB hole */
570 SYM_DATA_END(level2_fixmap_pgt)
572 SYM_DATA_START_PAGE_ALIGNED(level1_fixmap_pgt)
573 .rept (FIXMAP_PMD_NUM)
576 SYM_DATA_END(level1_fixmap_pgt)
583 SYM_DATA(early_gdt_descr, .word GDT_ENTRIES*8-1)
584 SYM_DATA_LOCAL(early_gdt_descr_base, .quad INIT_PER_CPU_VAR(gdt_page))
587 /* This must match the first entry in level2_kernel_pgt */
588 SYM_DATA(phys_base, .quad 0x0)
589 EXPORT_SYMBOL(phys_base)
591 #include "../../x86/xen/xen-head.S"
594 SYM_DATA_START_PAGE_ALIGNED(empty_zero_page)
596 SYM_DATA_END(empty_zero_page)
597 EXPORT_SYMBOL(empty_zero_page)