1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * 6 * Enhanced CPU detection and feature setting code by Mike Jagdis 7 * and Martin Mares, November 1997. 8 */ 9 10.text 11#include <linux/threads.h> 12#include <linux/init.h> 13#include <linux/linkage.h> 14#include <asm/segment.h> 15#include <asm/page_types.h> 16#include <asm/pgtable_types.h> 17#include <asm/cache.h> 18#include <asm/thread_info.h> 19#include <asm/asm-offsets.h> 20#include <asm/setup.h> 21#include <asm/processor-flags.h> 22#include <asm/msr-index.h> 23#include <asm/cpufeatures.h> 24#include <asm/percpu.h> 25#include <asm/nops.h> 26#include <asm/bootparam.h> 27#include <asm/export.h> 28#include <asm/pgtable_32.h> 29 30/* Physical address */ 31#define pa(X) ((X) - __PAGE_OFFSET) 32 33/* 34 * References to members of the new_cpu_data structure. 35 */ 36 37#define X86 new_cpu_data+CPUINFO_x86 38#define X86_VENDOR new_cpu_data+CPUINFO_x86_vendor 39#define X86_MODEL new_cpu_data+CPUINFO_x86_model 40#define X86_STEPPING new_cpu_data+CPUINFO_x86_stepping 41#define X86_HARD_MATH new_cpu_data+CPUINFO_hard_math 42#define X86_CPUID new_cpu_data+CPUINFO_cpuid_level 43#define X86_CAPABILITY new_cpu_data+CPUINFO_x86_capability 44#define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id 45 46 47#define SIZEOF_PTREGS 17*4 48 49/* 50 * Worst-case size of the kernel mapping we need to make: 51 * a relocatable kernel can live anywhere in lowmem, so we need to be able 52 * to map all of lowmem. 53 */ 54KERNEL_PAGES = LOWMEM_PAGES 55 56INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE 57RESERVE_BRK(pagetables, INIT_MAP_SIZE) 58 59/* 60 * 32-bit kernel entrypoint; only used by the boot CPU. On entry, 61 * %esi points to the real-mode code as a 32-bit pointer. 62 * CS and DS must be 4 GB flat segments, but we don't depend on 63 * any particular GDT layout, because we load our own as soon as we 64 * can. 65 */ 66__HEAD 67SYM_CODE_START(startup_32) 68 movl pa(initial_stack),%ecx 69 70 /* test KEEP_SEGMENTS flag to see if the bootloader is asking 71 us to not reload segments */ 72 testb $KEEP_SEGMENTS, BP_loadflags(%esi) 73 jnz 2f 74 75/* 76 * Set segments to known values. 77 */ 78 lgdt pa(boot_gdt_descr) 79 movl $(__BOOT_DS),%eax 80 movl %eax,%ds 81 movl %eax,%es 82 movl %eax,%fs 83 movl %eax,%gs 84 movl %eax,%ss 852: 86 leal -__PAGE_OFFSET(%ecx),%esp 87 88/* 89 * Clear BSS first so that there are no surprises... 90 */ 91 cld 92 xorl %eax,%eax 93 movl $pa(__bss_start),%edi 94 movl $pa(__bss_stop),%ecx 95 subl %edi,%ecx 96 shrl $2,%ecx 97 rep ; stosl 98/* 99 * Copy bootup parameters out of the way. 100 * Note: %esi still has the pointer to the real-mode data. 101 * With the kexec as boot loader, parameter segment might be loaded beyond 102 * kernel image and might not even be addressable by early boot page tables. 103 * (kexec on panic case). Hence copy out the parameters before initializing 104 * page tables. 105 */ 106 movl $pa(boot_params),%edi 107 movl $(PARAM_SIZE/4),%ecx 108 cld 109 rep 110 movsl 111 movl pa(boot_params) + NEW_CL_POINTER,%esi 112 andl %esi,%esi 113 jz 1f # No command line 114 movl $pa(boot_command_line),%edi 115 movl $(COMMAND_LINE_SIZE/4),%ecx 116 rep 117 movsl 1181: 119 120#ifdef CONFIG_OLPC 121 /* save OFW's pgdir table for later use when calling into OFW */ 122 movl %cr3, %eax 123 movl %eax, pa(olpc_ofw_pgd) 124#endif 125 126#ifdef CONFIG_MICROCODE 127 /* Early load ucode on BSP. */ 128 call load_ucode_bsp 129#endif 130 131 /* Create early pagetables. */ 132 call mk_early_pgtbl_32 133 134 /* Do early initialization of the fixmap area */ 135 movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax 136#ifdef CONFIG_X86_PAE 137#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ 138 movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) 139#else 140 movl %eax,pa(initial_page_table+0xffc) 141#endif 142 143#ifdef CONFIG_PARAVIRT 144 /* This is can only trip for a broken bootloader... */ 145 cmpw $0x207, pa(boot_params + BP_version) 146 jb .Ldefault_entry 147 148 /* Paravirt-compatible boot parameters. Look to see what architecture 149 we're booting under. */ 150 movl pa(boot_params + BP_hardware_subarch), %eax 151 cmpl $num_subarch_entries, %eax 152 jae .Lbad_subarch 153 154 movl pa(subarch_entries)(,%eax,4), %eax 155 subl $__PAGE_OFFSET, %eax 156 jmp *%eax 157 158.Lbad_subarch: 159SYM_INNER_LABEL_ALIGN(xen_entry, SYM_L_WEAK) 160 /* Unknown implementation; there's really 161 nothing we can do at this point. */ 162 ud2a 163 164 __INITDATA 165 166subarch_entries: 167 .long .Ldefault_entry /* normal x86/PC */ 168 .long xen_entry /* Xen hypervisor */ 169 .long .Ldefault_entry /* Moorestown MID */ 170num_subarch_entries = (. - subarch_entries) / 4 171.previous 172#else 173 jmp .Ldefault_entry 174#endif /* CONFIG_PARAVIRT */ 175SYM_CODE_END(startup_32) 176 177#ifdef CONFIG_HOTPLUG_CPU 178/* 179 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set 180 * up already except stack. We just set up stack here. Then call 181 * start_secondary(). 182 */ 183SYM_FUNC_START(start_cpu0) 184 movl initial_stack, %ecx 185 movl %ecx, %esp 186 call *(initial_code) 1871: jmp 1b 188SYM_FUNC_END(start_cpu0) 189#endif 190 191/* 192 * Non-boot CPU entry point; entered from trampoline.S 193 * We can't lgdt here, because lgdt itself uses a data segment, but 194 * we know the trampoline has already loaded the boot_gdt for us. 195 * 196 * If cpu hotplug is not supported then this code can go in init section 197 * which will be freed later 198 */ 199SYM_FUNC_START(startup_32_smp) 200 cld 201 movl $(__BOOT_DS),%eax 202 movl %eax,%ds 203 movl %eax,%es 204 movl %eax,%fs 205 movl %eax,%gs 206 movl pa(initial_stack),%ecx 207 movl %eax,%ss 208 leal -__PAGE_OFFSET(%ecx),%esp 209 210#ifdef CONFIG_MICROCODE 211 /* Early load ucode on AP. */ 212 call load_ucode_ap 213#endif 214 215.Ldefault_entry: 216 movl $(CR0_STATE & ~X86_CR0_PG),%eax 217 movl %eax,%cr0 218 219/* 220 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave 221 * bits like NT set. This would confuse the debugger if this code is traced. So 222 * initialize them properly now before switching to protected mode. That means 223 * DF in particular (even though we have cleared it earlier after copying the 224 * command line) because GCC expects it. 225 */ 226 pushl $0 227 popfl 228 229/* 230 * New page tables may be in 4Mbyte page mode and may be using the global pages. 231 * 232 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists 233 * if and only if CPUID exists and has flags other than the FPU flag set. 234 */ 235 movl $-1,pa(X86_CPUID) # preset CPUID level 236 movl $X86_EFLAGS_ID,%ecx 237 pushl %ecx 238 popfl # set EFLAGS=ID 239 pushfl 240 popl %eax # get EFLAGS 241 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set? 242 jz .Lenable_paging # hw disallowed setting of ID bit 243 # which means no CPUID and no CR4 244 245 xorl %eax,%eax 246 cpuid 247 movl %eax,pa(X86_CPUID) # save largest std CPUID function 248 249 movl $1,%eax 250 cpuid 251 andl $~1,%edx # Ignore CPUID.FPU 252 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4 253 254 movl pa(mmu_cr4_features),%eax 255 movl %eax,%cr4 256 257 testb $X86_CR4_PAE, %al # check if PAE is enabled 258 jz .Lenable_paging 259 260 /* Check if extended functions are implemented */ 261 movl $0x80000000, %eax 262 cpuid 263 /* Value must be in the range 0x80000001 to 0x8000ffff */ 264 subl $0x80000001, %eax 265 cmpl $(0x8000ffff-0x80000001), %eax 266 ja .Lenable_paging 267 268 /* Clear bogus XD_DISABLE bits */ 269 call verify_cpu 270 271 mov $0x80000001, %eax 272 cpuid 273 /* Execute Disable bit supported? */ 274 btl $(X86_FEATURE_NX & 31), %edx 275 jnc .Lenable_paging 276 277 /* Setup EFER (Extended Feature Enable Register) */ 278 movl $MSR_EFER, %ecx 279 rdmsr 280 281 btsl $_EFER_NX, %eax 282 /* Make changes effective */ 283 wrmsr 284 285.Lenable_paging: 286 287/* 288 * Enable paging 289 */ 290 movl $pa(initial_page_table), %eax 291 movl %eax,%cr3 /* set the page table pointer.. */ 292 movl $CR0_STATE,%eax 293 movl %eax,%cr0 /* ..and set paging (PG) bit */ 294 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ 2951: 296 /* Shift the stack pointer to a virtual address */ 297 addl $__PAGE_OFFSET, %esp 298 299/* 300 * start system 32-bit setup. We need to re-do some of the things done 301 * in 16-bit mode for the "real" operations. 302 */ 303 movl setup_once_ref,%eax 304 andl %eax,%eax 305 jz 1f # Did we do this already? 306 call *%eax 3071: 308 309/* 310 * Check if it is 486 311 */ 312 movb $4,X86 # at least 486 313 cmpl $-1,X86_CPUID 314 je .Lis486 315 316 /* get vendor info */ 317 xorl %eax,%eax # call CPUID with 0 -> return vendor ID 318 cpuid 319 movl %eax,X86_CPUID # save CPUID level 320 movl %ebx,X86_VENDOR_ID # lo 4 chars 321 movl %edx,X86_VENDOR_ID+4 # next 4 chars 322 movl %ecx,X86_VENDOR_ID+8 # last 4 chars 323 324 orl %eax,%eax # do we have processor info as well? 325 je .Lis486 326 327 movl $1,%eax # Use the CPUID instruction to get CPU type 328 cpuid 329 movb %al,%cl # save reg for future use 330 andb $0x0f,%ah # mask processor family 331 movb %ah,X86 332 andb $0xf0,%al # mask model 333 shrb $4,%al 334 movb %al,X86_MODEL 335 andb $0x0f,%cl # mask mask revision 336 movb %cl,X86_STEPPING 337 movl %edx,X86_CAPABILITY 338 339.Lis486: 340 movl $0x50022,%ecx # set AM, WP, NE and MP 341 movl %cr0,%eax 342 andl $0x80000011,%eax # Save PG,PE,ET 343 orl %ecx,%eax 344 movl %eax,%cr0 345 346 lgdt early_gdt_descr 347 ljmp $(__KERNEL_CS),$1f 3481: movl $(__KERNEL_DS),%eax # reload all the segment registers 349 movl %eax,%ss # after changing gdt. 350 351 movl $(__USER_DS),%eax # DS/ES contains default USER segment 352 movl %eax,%ds 353 movl %eax,%es 354 355 movl $(__KERNEL_PERCPU), %eax 356 movl %eax,%fs # set this cpu's percpu 357 358 movl $(__KERNEL_STACK_CANARY),%eax 359 movl %eax,%gs 360 361 xorl %eax,%eax # Clear LDT 362 lldt %ax 363 364 call *(initial_code) 3651: jmp 1b 366SYM_FUNC_END(startup_32_smp) 367 368#include "verify_cpu.S" 369 370/* 371 * setup_once 372 * 373 * The setup work we only want to run on the BSP. 374 * 375 * Warning: %esi is live across this function. 376 */ 377__INIT 378setup_once: 379#ifdef CONFIG_STACKPROTECTOR 380 /* 381 * Configure the stack canary. The linker can't handle this by 382 * relocation. Manually set base address in stack canary 383 * segment descriptor. 384 */ 385 movl $gdt_page,%eax 386 movl $stack_canary,%ecx 387 movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax) 388 shrl $16, %ecx 389 movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax) 390 movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax) 391#endif 392 393 andl $0,setup_once_ref /* Once is enough, thanks */ 394 ret 395 396SYM_FUNC_START(early_idt_handler_array) 397 # 36(%esp) %eflags 398 # 32(%esp) %cs 399 # 28(%esp) %eip 400 # 24(%rsp) error code 401 i = 0 402 .rept NUM_EXCEPTION_VECTORS 403 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 404 pushl $0 # Dummy error code, to make stack frame uniform 405 .endif 406 pushl $i # 20(%esp) Vector number 407 jmp early_idt_handler_common 408 i = i + 1 409 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 410 .endr 411SYM_FUNC_END(early_idt_handler_array) 412 413SYM_CODE_START_LOCAL(early_idt_handler_common) 414 /* 415 * The stack is the hardware frame, an error code or zero, and the 416 * vector number. 417 */ 418 cld 419 420 incl %ss:early_recursion_flag 421 422 /* The vector number is in pt_regs->gs */ 423 424 cld 425 pushl %fs /* pt_regs->fs (__fsh varies by model) */ 426 pushl %es /* pt_regs->es (__esh varies by model) */ 427 pushl %ds /* pt_regs->ds (__dsh varies by model) */ 428 pushl %eax /* pt_regs->ax */ 429 pushl %ebp /* pt_regs->bp */ 430 pushl %edi /* pt_regs->di */ 431 pushl %esi /* pt_regs->si */ 432 pushl %edx /* pt_regs->dx */ 433 pushl %ecx /* pt_regs->cx */ 434 pushl %ebx /* pt_regs->bx */ 435 436 /* Fix up DS and ES */ 437 movl $(__KERNEL_DS), %ecx 438 movl %ecx, %ds 439 movl %ecx, %es 440 441 /* Load the vector number into EDX */ 442 movl PT_GS(%esp), %edx 443 444 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ 445 movw %gs, PT_GS(%esp) 446 447 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ 448 call early_fixup_exception 449 450 popl %ebx /* pt_regs->bx */ 451 popl %ecx /* pt_regs->cx */ 452 popl %edx /* pt_regs->dx */ 453 popl %esi /* pt_regs->si */ 454 popl %edi /* pt_regs->di */ 455 popl %ebp /* pt_regs->bp */ 456 popl %eax /* pt_regs->ax */ 457 popl %ds /* pt_regs->ds (always ignores __dsh) */ 458 popl %es /* pt_regs->es (always ignores __esh) */ 459 popl %fs /* pt_regs->fs (always ignores __fsh) */ 460 popl %gs /* pt_regs->gs (always ignores __gsh) */ 461 decl %ss:early_recursion_flag 462 addl $4, %esp /* pop pt_regs->orig_ax */ 463 iret 464SYM_CODE_END(early_idt_handler_common) 465 466/* This is the default interrupt "handler" :-) */ 467SYM_FUNC_START(early_ignore_irq) 468 cld 469#ifdef CONFIG_PRINTK 470 pushl %eax 471 pushl %ecx 472 pushl %edx 473 pushl %es 474 pushl %ds 475 movl $(__KERNEL_DS),%eax 476 movl %eax,%ds 477 movl %eax,%es 478 cmpl $2,early_recursion_flag 479 je hlt_loop 480 incl early_recursion_flag 481 pushl 16(%esp) 482 pushl 24(%esp) 483 pushl 32(%esp) 484 pushl 40(%esp) 485 pushl $int_msg 486 call printk 487 488 call dump_stack 489 490 addl $(5*4),%esp 491 popl %ds 492 popl %es 493 popl %edx 494 popl %ecx 495 popl %eax 496#endif 497 iret 498 499hlt_loop: 500 hlt 501 jmp hlt_loop 502SYM_FUNC_END(early_ignore_irq) 503 504__INITDATA 505 .align 4 506SYM_DATA(early_recursion_flag, .long 0) 507 508__REFDATA 509 .align 4 510SYM_DATA(initial_code, .long i386_start_kernel) 511SYM_DATA(setup_once_ref, .long setup_once) 512 513#ifdef CONFIG_PAGE_TABLE_ISOLATION 514#define PGD_ALIGN (2 * PAGE_SIZE) 515#define PTI_USER_PGD_FILL 1024 516#else 517#define PGD_ALIGN (PAGE_SIZE) 518#define PTI_USER_PGD_FILL 0 519#endif 520/* 521 * BSS section 522 */ 523__PAGE_ALIGNED_BSS 524 .align PGD_ALIGN 525#ifdef CONFIG_X86_PAE 526.globl initial_pg_pmd 527initial_pg_pmd: 528 .fill 1024*KPMDS,4,0 529#else 530.globl initial_page_table 531initial_page_table: 532 .fill 1024,4,0 533#endif 534 .align PGD_ALIGN 535initial_pg_fixmap: 536 .fill 1024,4,0 537.globl swapper_pg_dir 538 .align PGD_ALIGN 539swapper_pg_dir: 540 .fill 1024,4,0 541 .fill PTI_USER_PGD_FILL,4,0 542.globl empty_zero_page 543empty_zero_page: 544 .fill 4096,1,0 545EXPORT_SYMBOL(empty_zero_page) 546 547/* 548 * This starts the data section. 549 */ 550#ifdef CONFIG_X86_PAE 551__PAGE_ALIGNED_DATA 552 /* Page-aligned for the benefit of paravirt? */ 553 .align PGD_ALIGN 554SYM_DATA_START(initial_page_table) 555 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */ 556# if KPMDS == 3 557 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 558 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 559 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0 560# elif KPMDS == 2 561 .long 0,0 562 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 563 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 564# elif KPMDS == 1 565 .long 0,0 566 .long 0,0 567 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 568# else 569# error "Kernel PMDs should be 1, 2 or 3" 570# endif 571 .align PAGE_SIZE /* needs to be page-sized too */ 572 573#ifdef CONFIG_PAGE_TABLE_ISOLATION 574 /* 575 * PTI needs another page so sync_initial_pagetable() works correctly 576 * and does not scribble over the data which is placed behind the 577 * actual initial_page_table. See clone_pgd_range(). 578 */ 579 .fill 1024, 4, 0 580#endif 581 582SYM_DATA_END(initial_page_table) 583#endif 584 585.data 586.balign 4 587/* 588 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder 589 * reliably detect the end of the stack. 590 */ 591SYM_DATA(initial_stack, 592 .long init_thread_union + THREAD_SIZE - 593 SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING) 594 595__INITRODATA 596int_msg: 597 .asciz "Unknown interrupt or fault at: %p %p %p\n" 598 599#include "../../x86/xen/xen-head.S" 600 601/* 602 * The IDT and GDT 'descriptors' are a strange 48-bit object 603 * only used by the lidt and lgdt instructions. They are not 604 * like usual segment descriptors - they consist of a 16-bit 605 * segment size, and 32-bit linear address value: 606 */ 607 608 .data 609 ALIGN 610# early boot GDT descriptor (must use 1:1 address mapping) 611 .word 0 # 32 bit align gdt_desc.address 612SYM_DATA_START_LOCAL(boot_gdt_descr) 613 .word __BOOT_DS+7 614 .long boot_gdt - __PAGE_OFFSET 615SYM_DATA_END(boot_gdt_descr) 616 617# boot GDT descriptor (later on used by CPU#0): 618 .word 0 # 32 bit align gdt_desc.address 619SYM_DATA_START(early_gdt_descr) 620 .word GDT_ENTRIES*8-1 621 .long gdt_page /* Overwritten for secondary CPUs */ 622SYM_DATA_END(early_gdt_descr) 623 624/* 625 * The boot_gdt must mirror the equivalent in setup.S and is 626 * used only for booting. 627 */ 628 .align L1_CACHE_BYTES 629SYM_DATA_START(boot_gdt) 630 .fill GDT_ENTRY_BOOT_CS,8,0 631 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ 632 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ 633SYM_DATA_END(boot_gdt) 634