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_MASK new_cpu_data+CPUINFO_x86_mask 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 67ENTRY(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: 159WEAK(xen_entry) 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 */ 175 176#ifdef CONFIG_HOTPLUG_CPU 177/* 178 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set 179 * up already except stack. We just set up stack here. Then call 180 * start_secondary(). 181 */ 182ENTRY(start_cpu0) 183 movl initial_stack, %ecx 184 movl %ecx, %esp 185 call *(initial_code) 1861: jmp 1b 187ENDPROC(start_cpu0) 188#endif 189 190/* 191 * Non-boot CPU entry point; entered from trampoline.S 192 * We can't lgdt here, because lgdt itself uses a data segment, but 193 * we know the trampoline has already loaded the boot_gdt for us. 194 * 195 * If cpu hotplug is not supported then this code can go in init section 196 * which will be freed later 197 */ 198ENTRY(startup_32_smp) 199 cld 200 movl $(__BOOT_DS),%eax 201 movl %eax,%ds 202 movl %eax,%es 203 movl %eax,%fs 204 movl %eax,%gs 205 movl pa(initial_stack),%ecx 206 movl %eax,%ss 207 leal -__PAGE_OFFSET(%ecx),%esp 208 209#ifdef CONFIG_MICROCODE 210 /* Early load ucode on AP. */ 211 call load_ucode_ap 212#endif 213 214.Ldefault_entry: 215#define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \ 216 X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \ 217 X86_CR0_PG) 218 movl $(CR0_STATE & ~X86_CR0_PG),%eax 219 movl %eax,%cr0 220 221/* 222 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave 223 * bits like NT set. This would confuse the debugger if this code is traced. So 224 * initialize them properly now before switching to protected mode. That means 225 * DF in particular (even though we have cleared it earlier after copying the 226 * command line) because GCC expects it. 227 */ 228 pushl $0 229 popfl 230 231/* 232 * New page tables may be in 4Mbyte page mode and may be using the global pages. 233 * 234 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists 235 * if and only if CPUID exists and has flags other than the FPU flag set. 236 */ 237 movl $-1,pa(X86_CPUID) # preset CPUID level 238 movl $X86_EFLAGS_ID,%ecx 239 pushl %ecx 240 popfl # set EFLAGS=ID 241 pushfl 242 popl %eax # get EFLAGS 243 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set? 244 jz .Lenable_paging # hw disallowed setting of ID bit 245 # which means no CPUID and no CR4 246 247 xorl %eax,%eax 248 cpuid 249 movl %eax,pa(X86_CPUID) # save largest std CPUID function 250 251 movl $1,%eax 252 cpuid 253 andl $~1,%edx # Ignore CPUID.FPU 254 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4 255 256 movl pa(mmu_cr4_features),%eax 257 movl %eax,%cr4 258 259 testb $X86_CR4_PAE, %al # check if PAE is enabled 260 jz .Lenable_paging 261 262 /* Check if extended functions are implemented */ 263 movl $0x80000000, %eax 264 cpuid 265 /* Value must be in the range 0x80000001 to 0x8000ffff */ 266 subl $0x80000001, %eax 267 cmpl $(0x8000ffff-0x80000001), %eax 268 ja .Lenable_paging 269 270 /* Clear bogus XD_DISABLE bits */ 271 call verify_cpu 272 273 mov $0x80000001, %eax 274 cpuid 275 /* Execute Disable bit supported? */ 276 btl $(X86_FEATURE_NX & 31), %edx 277 jnc .Lenable_paging 278 279 /* Setup EFER (Extended Feature Enable Register) */ 280 movl $MSR_EFER, %ecx 281 rdmsr 282 283 btsl $_EFER_NX, %eax 284 /* Make changes effective */ 285 wrmsr 286 287.Lenable_paging: 288 289/* 290 * Enable paging 291 */ 292 movl $pa(initial_page_table), %eax 293 movl %eax,%cr3 /* set the page table pointer.. */ 294 movl $CR0_STATE,%eax 295 movl %eax,%cr0 /* ..and set paging (PG) bit */ 296 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ 2971: 298 /* Shift the stack pointer to a virtual address */ 299 addl $__PAGE_OFFSET, %esp 300 301/* 302 * start system 32-bit setup. We need to re-do some of the things done 303 * in 16-bit mode for the "real" operations. 304 */ 305 movl setup_once_ref,%eax 306 andl %eax,%eax 307 jz 1f # Did we do this already? 308 call *%eax 3091: 310 311/* 312 * Check if it is 486 313 */ 314 movb $4,X86 # at least 486 315 cmpl $-1,X86_CPUID 316 je .Lis486 317 318 /* get vendor info */ 319 xorl %eax,%eax # call CPUID with 0 -> return vendor ID 320 cpuid 321 movl %eax,X86_CPUID # save CPUID level 322 movl %ebx,X86_VENDOR_ID # lo 4 chars 323 movl %edx,X86_VENDOR_ID+4 # next 4 chars 324 movl %ecx,X86_VENDOR_ID+8 # last 4 chars 325 326 orl %eax,%eax # do we have processor info as well? 327 je .Lis486 328 329 movl $1,%eax # Use the CPUID instruction to get CPU type 330 cpuid 331 movb %al,%cl # save reg for future use 332 andb $0x0f,%ah # mask processor family 333 movb %ah,X86 334 andb $0xf0,%al # mask model 335 shrb $4,%al 336 movb %al,X86_MODEL 337 andb $0x0f,%cl # mask mask revision 338 movb %cl,X86_MASK 339 movl %edx,X86_CAPABILITY 340 341.Lis486: 342 movl $0x50022,%ecx # set AM, WP, NE and MP 343 movl %cr0,%eax 344 andl $0x80000011,%eax # Save PG,PE,ET 345 orl %ecx,%eax 346 movl %eax,%cr0 347 348 lgdt early_gdt_descr 349 ljmp $(__KERNEL_CS),$1f 3501: movl $(__KERNEL_DS),%eax # reload all the segment registers 351 movl %eax,%ss # after changing gdt. 352 353 movl $(__USER_DS),%eax # DS/ES contains default USER segment 354 movl %eax,%ds 355 movl %eax,%es 356 357 movl $(__KERNEL_PERCPU), %eax 358 movl %eax,%fs # set this cpu's percpu 359 360 movl $(__KERNEL_STACK_CANARY),%eax 361 movl %eax,%gs 362 363 xorl %eax,%eax # Clear LDT 364 lldt %ax 365 366 call *(initial_code) 3671: jmp 1b 368ENDPROC(startup_32_smp) 369 370#include "verify_cpu.S" 371 372/* 373 * setup_once 374 * 375 * The setup work we only want to run on the BSP. 376 * 377 * Warning: %esi is live across this function. 378 */ 379__INIT 380setup_once: 381#ifdef CONFIG_CC_STACKPROTECTOR 382 /* 383 * Configure the stack canary. The linker can't handle this by 384 * relocation. Manually set base address in stack canary 385 * segment descriptor. 386 */ 387 movl $gdt_page,%eax 388 movl $stack_canary,%ecx 389 movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax) 390 shrl $16, %ecx 391 movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax) 392 movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax) 393#endif 394 395 andl $0,setup_once_ref /* Once is enough, thanks */ 396 ret 397 398ENTRY(early_idt_handler_array) 399 # 36(%esp) %eflags 400 # 32(%esp) %cs 401 # 28(%esp) %eip 402 # 24(%rsp) error code 403 i = 0 404 .rept NUM_EXCEPTION_VECTORS 405 .ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1 406 pushl $0 # Dummy error code, to make stack frame uniform 407 .endif 408 pushl $i # 20(%esp) Vector number 409 jmp early_idt_handler_common 410 i = i + 1 411 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 412 .endr 413ENDPROC(early_idt_handler_array) 414 415early_idt_handler_common: 416 /* 417 * The stack is the hardware frame, an error code or zero, and the 418 * vector number. 419 */ 420 cld 421 422 incl %ss:early_recursion_flag 423 424 /* The vector number is in pt_regs->gs */ 425 426 cld 427 pushl %fs /* pt_regs->fs (__fsh varies by model) */ 428 pushl %es /* pt_regs->es (__esh varies by model) */ 429 pushl %ds /* pt_regs->ds (__dsh varies by model) */ 430 pushl %eax /* pt_regs->ax */ 431 pushl %ebp /* pt_regs->bp */ 432 pushl %edi /* pt_regs->di */ 433 pushl %esi /* pt_regs->si */ 434 pushl %edx /* pt_regs->dx */ 435 pushl %ecx /* pt_regs->cx */ 436 pushl %ebx /* pt_regs->bx */ 437 438 /* Fix up DS and ES */ 439 movl $(__KERNEL_DS), %ecx 440 movl %ecx, %ds 441 movl %ecx, %es 442 443 /* Load the vector number into EDX */ 444 movl PT_GS(%esp), %edx 445 446 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ 447 movw %gs, PT_GS(%esp) 448 449 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ 450 call early_fixup_exception 451 452 popl %ebx /* pt_regs->bx */ 453 popl %ecx /* pt_regs->cx */ 454 popl %edx /* pt_regs->dx */ 455 popl %esi /* pt_regs->si */ 456 popl %edi /* pt_regs->di */ 457 popl %ebp /* pt_regs->bp */ 458 popl %eax /* pt_regs->ax */ 459 popl %ds /* pt_regs->ds (always ignores __dsh) */ 460 popl %es /* pt_regs->es (always ignores __esh) */ 461 popl %fs /* pt_regs->fs (always ignores __fsh) */ 462 popl %gs /* pt_regs->gs (always ignores __gsh) */ 463 decl %ss:early_recursion_flag 464 addl $4, %esp /* pop pt_regs->orig_ax */ 465 iret 466ENDPROC(early_idt_handler_common) 467 468/* This is the default interrupt "handler" :-) */ 469ENTRY(early_ignore_irq) 470 cld 471#ifdef CONFIG_PRINTK 472 pushl %eax 473 pushl %ecx 474 pushl %edx 475 pushl %es 476 pushl %ds 477 movl $(__KERNEL_DS),%eax 478 movl %eax,%ds 479 movl %eax,%es 480 cmpl $2,early_recursion_flag 481 je hlt_loop 482 incl early_recursion_flag 483 pushl 16(%esp) 484 pushl 24(%esp) 485 pushl 32(%esp) 486 pushl 40(%esp) 487 pushl $int_msg 488 call printk 489 490 call dump_stack 491 492 addl $(5*4),%esp 493 popl %ds 494 popl %es 495 popl %edx 496 popl %ecx 497 popl %eax 498#endif 499 iret 500 501hlt_loop: 502 hlt 503 jmp hlt_loop 504ENDPROC(early_ignore_irq) 505 506__INITDATA 507 .align 4 508GLOBAL(early_recursion_flag) 509 .long 0 510 511__REFDATA 512 .align 4 513ENTRY(initial_code) 514 .long i386_start_kernel 515ENTRY(setup_once_ref) 516 .long setup_once 517 518/* 519 * BSS section 520 */ 521__PAGE_ALIGNED_BSS 522 .align PAGE_SIZE 523#ifdef CONFIG_X86_PAE 524.globl initial_pg_pmd 525initial_pg_pmd: 526 .fill 1024*KPMDS,4,0 527#else 528.globl initial_page_table 529initial_page_table: 530 .fill 1024,4,0 531#endif 532initial_pg_fixmap: 533 .fill 1024,4,0 534.globl empty_zero_page 535empty_zero_page: 536 .fill 4096,1,0 537.globl swapper_pg_dir 538swapper_pg_dir: 539 .fill 1024,4,0 540EXPORT_SYMBOL(empty_zero_page) 541 542/* 543 * This starts the data section. 544 */ 545#ifdef CONFIG_X86_PAE 546__PAGE_ALIGNED_DATA 547 /* Page-aligned for the benefit of paravirt? */ 548 .align PAGE_SIZE 549ENTRY(initial_page_table) 550 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */ 551# if KPMDS == 3 552 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 553 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 554 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0 555# elif KPMDS == 2 556 .long 0,0 557 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 558 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 559# elif KPMDS == 1 560 .long 0,0 561 .long 0,0 562 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 563# else 564# error "Kernel PMDs should be 1, 2 or 3" 565# endif 566 .align PAGE_SIZE /* needs to be page-sized too */ 567#endif 568 569.data 570.balign 4 571ENTRY(initial_stack) 572 /* 573 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel 574 * unwinder reliably detect the end of the stack. 575 */ 576 .long init_thread_union + THREAD_SIZE - SIZEOF_PTREGS - \ 577 TOP_OF_KERNEL_STACK_PADDING; 578 579__INITRODATA 580int_msg: 581 .asciz "Unknown interrupt or fault at: %p %p %p\n" 582 583#include "../../x86/xen/xen-head.S" 584 585/* 586 * The IDT and GDT 'descriptors' are a strange 48-bit object 587 * only used by the lidt and lgdt instructions. They are not 588 * like usual segment descriptors - they consist of a 16-bit 589 * segment size, and 32-bit linear address value: 590 */ 591 592 .data 593.globl boot_gdt_descr 594 595 ALIGN 596# early boot GDT descriptor (must use 1:1 address mapping) 597 .word 0 # 32 bit align gdt_desc.address 598boot_gdt_descr: 599 .word __BOOT_DS+7 600 .long boot_gdt - __PAGE_OFFSET 601 602# boot GDT descriptor (later on used by CPU#0): 603 .word 0 # 32 bit align gdt_desc.address 604ENTRY(early_gdt_descr) 605 .word GDT_ENTRIES*8-1 606 .long gdt_page /* Overwritten for secondary CPUs */ 607 608/* 609 * The boot_gdt must mirror the equivalent in setup.S and is 610 * used only for booting. 611 */ 612 .align L1_CACHE_BYTES 613ENTRY(boot_gdt) 614 .fill GDT_ENTRY_BOOT_CS,8,0 615 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ 616 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ 617