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 13#include <linux/linkage.h> 14#include <linux/threads.h> 15#include <linux/init.h> 16#include <asm/segment.h> 17#include <asm/pgtable.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/export.h> 26#include <asm/nospec-branch.h> 27#include <asm/fixmap.h> 28 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_RAX ; movq %rax, reg 33#else 34#define GET_CR2_INTO(reg) movq %cr2, reg 35#define INTERRUPT_RETURN iretq 36#endif 37 38/* we are not able to switch in one step to the final KERNEL ADDRESS SPACE 39 * because we need identity-mapped pages. 40 * 41 */ 42 43#define l4_index(x) (((x) >> 39) & 511) 44#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1)) 45 46L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE_L4) 47L4_START_KERNEL = l4_index(__START_KERNEL_map) 48 49L3_START_KERNEL = pud_index(__START_KERNEL_map) 50 51 .text 52 __HEAD 53 .code64 54 .globl startup_64 55startup_64: 56 UNWIND_HINT_EMPTY 57 /* 58 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0, 59 * and someone has loaded an identity mapped page table 60 * for us. These identity mapped page tables map all of the 61 * kernel pages and possibly all of memory. 62 * 63 * %rsi holds a physical pointer to real_mode_data. 64 * 65 * We come here either directly from a 64bit bootloader, or from 66 * arch/x86/boot/compressed/head_64.S. 67 * 68 * We only come here initially at boot nothing else comes here. 69 * 70 * Since we may be loaded at an address different from what we were 71 * compiled to run at we first fixup the physical addresses in our page 72 * tables and then reload them. 73 */ 74 75 /* Set up the stack for verify_cpu(), similar to initial_stack below */ 76 leaq (__end_init_task - SIZEOF_PTREGS)(%rip), %rsp 77 78 /* Sanitize CPU configuration */ 79 call verify_cpu 80 81 /* 82 * Perform pagetable fixups. Additionally, if SME is active, encrypt 83 * the kernel and retrieve the modifier (SME encryption mask if SME 84 * is active) to be added to the initial pgdir entry that will be 85 * programmed into CR3. 86 */ 87 leaq _text(%rip), %rdi 88 pushq %rsi 89 call __startup_64 90 popq %rsi 91 92 /* Form the CR3 value being sure to include the CR3 modifier */ 93 addq $(early_top_pgt - __START_KERNEL_map), %rax 94 jmp 1f 95ENTRY(secondary_startup_64) 96 UNWIND_HINT_EMPTY 97 /* 98 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0, 99 * and someone has loaded a mapped page table. 100 * 101 * %rsi holds a physical pointer to real_mode_data. 102 * 103 * We come here either from startup_64 (using physical addresses) 104 * or from trampoline.S (using virtual addresses). 105 * 106 * Using virtual addresses from trampoline.S removes the need 107 * to have any identity mapped pages in the kernel page table 108 * after the boot processor executes this code. 109 */ 110 111 /* Sanitize CPU configuration */ 112 call verify_cpu 113 114 /* 115 * Retrieve the modifier (SME encryption mask if SME is active) to be 116 * added to the initial pgdir entry that will be programmed into CR3. 117 */ 118 pushq %rsi 119 call __startup_secondary_64 120 popq %rsi 121 122 /* Form the CR3 value being sure to include the CR3 modifier */ 123 addq $(init_top_pgt - __START_KERNEL_map), %rax 1241: 125 126 /* Enable PAE mode, PGE and LA57 */ 127 movl $(X86_CR4_PAE | X86_CR4_PGE), %ecx 128#ifdef CONFIG_X86_5LEVEL 129 testl $1, __pgtable_l5_enabled(%rip) 130 jz 1f 131 orl $X86_CR4_LA57, %ecx 1321: 133#endif 134 movq %rcx, %cr4 135 136 /* Setup early boot stage 4-/5-level pagetables. */ 137 addq phys_base(%rip), %rax 138 movq %rax, %cr3 139 140 /* Ensure I am executing from virtual addresses */ 141 movq $1f, %rax 142 ANNOTATE_RETPOLINE_SAFE 143 jmp *%rax 1441: 145 UNWIND_HINT_EMPTY 146 147 /* Check if nx is implemented */ 148 movl $0x80000001, %eax 149 cpuid 150 movl %edx,%edi 151 152 /* Setup EFER (Extended Feature Enable Register) */ 153 movl $MSR_EFER, %ecx 154 rdmsr 155 btsl $_EFER_SCE, %eax /* Enable System Call */ 156 btl $20,%edi /* No Execute supported? */ 157 jnc 1f 158 btsl $_EFER_NX, %eax 159 btsq $_PAGE_BIT_NX,early_pmd_flags(%rip) 1601: wrmsr /* Make changes effective */ 161 162 /* Setup cr0 */ 163 movl $CR0_STATE, %eax 164 /* Make changes effective */ 165 movq %rax, %cr0 166 167 /* Setup a boot time stack */ 168 movq initial_stack(%rip), %rsp 169 170 /* zero EFLAGS after setting rsp */ 171 pushq $0 172 popfq 173 174 /* 175 * We must switch to a new descriptor in kernel space for the GDT 176 * because soon the kernel won't have access anymore to the userspace 177 * addresses where we're currently running on. We have to do that here 178 * because in 32bit we couldn't load a 64bit linear address. 179 */ 180 lgdt early_gdt_descr(%rip) 181 182 /* set up data segments */ 183 xorl %eax,%eax 184 movl %eax,%ds 185 movl %eax,%ss 186 movl %eax,%es 187 188 /* 189 * We don't really need to load %fs or %gs, but load them anyway 190 * to kill any stale realmode selectors. This allows execution 191 * under VT hardware. 192 */ 193 movl %eax,%fs 194 movl %eax,%gs 195 196 /* Set up %gs. 197 * 198 * The base of %gs always points to the bottom of the irqstack 199 * union. If the stack protector canary is enabled, it is 200 * located at %gs:40. Note that, on SMP, the boot cpu uses 201 * init data section till per cpu areas are set up. 202 */ 203 movl $MSR_GS_BASE,%ecx 204 movl initial_gs(%rip),%eax 205 movl initial_gs+4(%rip),%edx 206 wrmsr 207 208 /* rsi is pointer to real mode structure with interesting info. 209 pass it to C */ 210 movq %rsi, %rdi 211 212.Ljump_to_C_code: 213 /* 214 * Jump to run C code and to be on a real kernel address. 215 * Since we are running on identity-mapped space we have to jump 216 * to the full 64bit address, this is only possible as indirect 217 * jump. In addition we need to ensure %cs is set so we make this 218 * a far return. 219 * 220 * Note: do not change to far jump indirect with 64bit offset. 221 * 222 * AMD does not support far jump indirect with 64bit offset. 223 * AMD64 Architecture Programmer's Manual, Volume 3: states only 224 * JMP FAR mem16:16 FF /5 Far jump indirect, 225 * with the target specified by a far pointer in memory. 226 * JMP FAR mem16:32 FF /5 Far jump indirect, 227 * with the target specified by a far pointer in memory. 228 * 229 * Intel64 does support 64bit offset. 230 * Software Developer Manual Vol 2: states: 231 * FF /5 JMP m16:16 Jump far, absolute indirect, 232 * address given in m16:16 233 * FF /5 JMP m16:32 Jump far, absolute indirect, 234 * address given in m16:32. 235 * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect, 236 * address given in m16:64. 237 */ 238 pushq $.Lafter_lret # put return address on stack for unwinder 239 xorl %ebp, %ebp # clear frame pointer 240 movq initial_code(%rip), %rax 241 pushq $__KERNEL_CS # set correct cs 242 pushq %rax # target address in negative space 243 lretq 244.Lafter_lret: 245END(secondary_startup_64) 246 247#include "verify_cpu.S" 248 249#ifdef CONFIG_HOTPLUG_CPU 250/* 251 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set 252 * up already except stack. We just set up stack here. Then call 253 * start_secondary() via .Ljump_to_C_code. 254 */ 255ENTRY(start_cpu0) 256 movq initial_stack(%rip), %rsp 257 UNWIND_HINT_EMPTY 258 jmp .Ljump_to_C_code 259ENDPROC(start_cpu0) 260#endif 261 262 /* Both SMP bootup and ACPI suspend change these variables */ 263 __REFDATA 264 .balign 8 265 GLOBAL(initial_code) 266 .quad x86_64_start_kernel 267 GLOBAL(initial_gs) 268 .quad INIT_PER_CPU_VAR(irq_stack_union) 269 GLOBAL(initial_stack) 270 /* 271 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel 272 * unwinder reliably detect the end of the stack. 273 */ 274 .quad init_thread_union + THREAD_SIZE - SIZEOF_PTREGS 275 __FINITDATA 276 277 __INIT 278ENTRY(early_idt_handler_array) 279 i = 0 280 .rept NUM_EXCEPTION_VECTORS 281 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 282 UNWIND_HINT_IRET_REGS 283 pushq $0 # Dummy error code, to make stack frame uniform 284 .else 285 UNWIND_HINT_IRET_REGS offset=8 286 .endif 287 pushq $i # 72(%rsp) Vector number 288 jmp early_idt_handler_common 289 UNWIND_HINT_IRET_REGS 290 i = i + 1 291 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 292 .endr 293 UNWIND_HINT_IRET_REGS offset=16 294END(early_idt_handler_array) 295 296early_idt_handler_common: 297 /* 298 * The stack is the hardware frame, an error code or zero, and the 299 * vector number. 300 */ 301 cld 302 303 incl early_recursion_flag(%rip) 304 305 /* The vector number is currently in the pt_regs->di slot. */ 306 pushq %rsi /* pt_regs->si */ 307 movq 8(%rsp), %rsi /* RSI = vector number */ 308 movq %rdi, 8(%rsp) /* pt_regs->di = RDI */ 309 pushq %rdx /* pt_regs->dx */ 310 pushq %rcx /* pt_regs->cx */ 311 pushq %rax /* pt_regs->ax */ 312 pushq %r8 /* pt_regs->r8 */ 313 pushq %r9 /* pt_regs->r9 */ 314 pushq %r10 /* pt_regs->r10 */ 315 pushq %r11 /* pt_regs->r11 */ 316 pushq %rbx /* pt_regs->bx */ 317 pushq %rbp /* pt_regs->bp */ 318 pushq %r12 /* pt_regs->r12 */ 319 pushq %r13 /* pt_regs->r13 */ 320 pushq %r14 /* pt_regs->r14 */ 321 pushq %r15 /* pt_regs->r15 */ 322 UNWIND_HINT_REGS 323 324 cmpq $14,%rsi /* Page fault? */ 325 jnz 10f 326 GET_CR2_INTO(%rdi) /* Can clobber any volatile register if pv */ 327 call early_make_pgtable 328 andl %eax,%eax 329 jz 20f /* All good */ 330 33110: 332 movq %rsp,%rdi /* RDI = pt_regs; RSI is already trapnr */ 333 call early_fixup_exception 334 33520: 336 decl early_recursion_flag(%rip) 337 jmp restore_regs_and_return_to_kernel 338END(early_idt_handler_common) 339 340 __INITDATA 341 342 .balign 4 343GLOBAL(early_recursion_flag) 344 .long 0 345 346#define NEXT_PAGE(name) \ 347 .balign PAGE_SIZE; \ 348GLOBAL(name) 349 350#ifdef CONFIG_PAGE_TABLE_ISOLATION 351/* 352 * Each PGD needs to be 8k long and 8k aligned. We do not 353 * ever go out to userspace with these, so we do not 354 * strictly *need* the second page, but this allows us to 355 * have a single set_pgd() implementation that does not 356 * need to worry about whether it has 4k or 8k to work 357 * with. 358 * 359 * This ensures PGDs are 8k long: 360 */ 361#define PTI_USER_PGD_FILL 512 362/* This ensures they are 8k-aligned: */ 363#define NEXT_PGD_PAGE(name) \ 364 .balign 2 * PAGE_SIZE; \ 365GLOBAL(name) 366#else 367#define NEXT_PGD_PAGE(name) NEXT_PAGE(name) 368#define PTI_USER_PGD_FILL 0 369#endif 370 371/* Automate the creation of 1 to 1 mapping pmd entries */ 372#define PMDS(START, PERM, COUNT) \ 373 i = 0 ; \ 374 .rept (COUNT) ; \ 375 .quad (START) + (i << PMD_SHIFT) + (PERM) ; \ 376 i = i + 1 ; \ 377 .endr 378 379 __INITDATA 380NEXT_PGD_PAGE(early_top_pgt) 381 .fill 512,8,0 382 .fill PTI_USER_PGD_FILL,8,0 383 384NEXT_PAGE(early_dynamic_pgts) 385 .fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0 386 387 .data 388 389#if defined(CONFIG_XEN_PV) || defined(CONFIG_PVH) 390NEXT_PGD_PAGE(init_top_pgt) 391 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 392 .org init_top_pgt + L4_PAGE_OFFSET*8, 0 393 .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 394 .org init_top_pgt + L4_START_KERNEL*8, 0 395 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */ 396 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 397 .fill PTI_USER_PGD_FILL,8,0 398 399NEXT_PAGE(level3_ident_pgt) 400 .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 401 .fill 511, 8, 0 402NEXT_PAGE(level2_ident_pgt) 403 /* 404 * Since I easily can, map the first 1G. 405 * Don't set NX because code runs from these pages. 406 * 407 * Note: This sets _PAGE_GLOBAL despite whether 408 * the CPU supports it or it is enabled. But, 409 * the CPU should ignore the bit. 410 */ 411 PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD) 412#else 413NEXT_PGD_PAGE(init_top_pgt) 414 .fill 512,8,0 415 .fill PTI_USER_PGD_FILL,8,0 416#endif 417 418#ifdef CONFIG_X86_5LEVEL 419NEXT_PAGE(level4_kernel_pgt) 420 .fill 511,8,0 421 .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 422#endif 423 424NEXT_PAGE(level3_kernel_pgt) 425 .fill L3_START_KERNEL,8,0 426 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */ 427 .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC 428 .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC 429 430NEXT_PAGE(level2_kernel_pgt) 431 /* 432 * 512 MB kernel mapping. We spend a full page on this pagetable 433 * anyway. 434 * 435 * The kernel code+data+bss must not be bigger than that. 436 * 437 * (NOTE: at +512MB starts the module area, see MODULES_VADDR. 438 * If you want to increase this then increase MODULES_VADDR 439 * too.) 440 * 441 * This table is eventually used by the kernel during normal 442 * runtime. Care must be taken to clear out undesired bits 443 * later, like _PAGE_RW or _PAGE_GLOBAL in some cases. 444 */ 445 PMDS(0, __PAGE_KERNEL_LARGE_EXEC, 446 KERNEL_IMAGE_SIZE/PMD_SIZE) 447 448NEXT_PAGE(level2_fixmap_pgt) 449 .fill (512 - 4 - FIXMAP_PMD_NUM),8,0 450 pgtno = 0 451 .rept (FIXMAP_PMD_NUM) 452 .quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \ 453 + _PAGE_TABLE_NOENC; 454 pgtno = pgtno + 1 455 .endr 456 /* 6 MB reserved space + a 2MB hole */ 457 .fill 4,8,0 458 459NEXT_PAGE(level1_fixmap_pgt) 460 .rept (FIXMAP_PMD_NUM) 461 .fill 512,8,0 462 .endr 463 464#undef PMDS 465 466 .data 467 .align 16 468 .globl early_gdt_descr 469early_gdt_descr: 470 .word GDT_ENTRIES*8-1 471early_gdt_descr_base: 472 .quad INIT_PER_CPU_VAR(gdt_page) 473 474ENTRY(phys_base) 475 /* This must match the first entry in level2_kernel_pgt */ 476 .quad 0x0000000000000000 477EXPORT_SYMBOL(phys_base) 478 479#include "../../x86/xen/xen-head.S" 480 481 __PAGE_ALIGNED_BSS 482NEXT_PAGE(empty_zero_page) 483 .skip PAGE_SIZE 484EXPORT_SYMBOL(empty_zero_page) 485 486