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/* 71 * Set segments to known values. 72 */ 73 lgdt pa(boot_gdt_descr) 74 movl $(__BOOT_DS),%eax 75 movl %eax,%ds 76 movl %eax,%es 77 movl %eax,%fs 78 movl %eax,%gs 79 movl %eax,%ss 80 leal -__PAGE_OFFSET(%ecx),%esp 81 82/* 83 * Clear BSS first so that there are no surprises... 84 */ 85 cld 86 xorl %eax,%eax 87 movl $pa(__bss_start),%edi 88 movl $pa(__bss_stop),%ecx 89 subl %edi,%ecx 90 shrl $2,%ecx 91 rep ; stosl 92/* 93 * Copy bootup parameters out of the way. 94 * Note: %esi still has the pointer to the real-mode data. 95 * With the kexec as boot loader, parameter segment might be loaded beyond 96 * kernel image and might not even be addressable by early boot page tables. 97 * (kexec on panic case). Hence copy out the parameters before initializing 98 * page tables. 99 */ 100 movl $pa(boot_params),%edi 101 movl $(PARAM_SIZE/4),%ecx 102 cld 103 rep 104 movsl 105 movl pa(boot_params) + NEW_CL_POINTER,%esi 106 andl %esi,%esi 107 jz 1f # No command line 108 movl $pa(boot_command_line),%edi 109 movl $(COMMAND_LINE_SIZE/4),%ecx 110 rep 111 movsl 1121: 113 114#ifdef CONFIG_OLPC 115 /* save OFW's pgdir table for later use when calling into OFW */ 116 movl %cr3, %eax 117 movl %eax, pa(olpc_ofw_pgd) 118#endif 119 120#ifdef CONFIG_MICROCODE 121 /* Early load ucode on BSP. */ 122 call load_ucode_bsp 123#endif 124 125 /* Create early pagetables. */ 126 call mk_early_pgtbl_32 127 128 /* Do early initialization of the fixmap area */ 129 movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax 130#ifdef CONFIG_X86_PAE 131#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ 132 movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) 133#else 134 movl %eax,pa(initial_page_table+0xffc) 135#endif 136 137#ifdef CONFIG_PARAVIRT 138 /* This is can only trip for a broken bootloader... */ 139 cmpw $0x207, pa(boot_params + BP_version) 140 jb .Ldefault_entry 141 142 /* Paravirt-compatible boot parameters. Look to see what architecture 143 we're booting under. */ 144 movl pa(boot_params + BP_hardware_subarch), %eax 145 cmpl $num_subarch_entries, %eax 146 jae .Lbad_subarch 147 148 movl pa(subarch_entries)(,%eax,4), %eax 149 subl $__PAGE_OFFSET, %eax 150 jmp *%eax 151 152.Lbad_subarch: 153SYM_INNER_LABEL_ALIGN(xen_entry, SYM_L_WEAK) 154 /* Unknown implementation; there's really 155 nothing we can do at this point. */ 156 ud2a 157 158 __INITDATA 159 160subarch_entries: 161 .long .Ldefault_entry /* normal x86/PC */ 162 .long xen_entry /* Xen hypervisor */ 163 .long .Ldefault_entry /* Moorestown MID */ 164num_subarch_entries = (. - subarch_entries) / 4 165.previous 166#else 167 jmp .Ldefault_entry 168#endif /* CONFIG_PARAVIRT */ 169SYM_CODE_END(startup_32) 170 171#ifdef CONFIG_HOTPLUG_CPU 172/* 173 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set 174 * up already except stack. We just set up stack here. Then call 175 * start_secondary(). 176 */ 177SYM_FUNC_START(start_cpu0) 178 movl initial_stack, %ecx 179 movl %ecx, %esp 180 call *(initial_code) 1811: jmp 1b 182SYM_FUNC_END(start_cpu0) 183#endif 184 185/* 186 * Non-boot CPU entry point; entered from trampoline.S 187 * We can't lgdt here, because lgdt itself uses a data segment, but 188 * we know the trampoline has already loaded the boot_gdt for us. 189 * 190 * If cpu hotplug is not supported then this code can go in init section 191 * which will be freed later 192 */ 193SYM_FUNC_START(startup_32_smp) 194 cld 195 movl $(__BOOT_DS),%eax 196 movl %eax,%ds 197 movl %eax,%es 198 movl %eax,%fs 199 movl %eax,%gs 200 movl pa(initial_stack),%ecx 201 movl %eax,%ss 202 leal -__PAGE_OFFSET(%ecx),%esp 203 204#ifdef CONFIG_MICROCODE 205 /* Early load ucode on AP. */ 206 call load_ucode_ap 207#endif 208 209.Ldefault_entry: 210 movl $(CR0_STATE & ~X86_CR0_PG),%eax 211 movl %eax,%cr0 212 213/* 214 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave 215 * bits like NT set. This would confuse the debugger if this code is traced. So 216 * initialize them properly now before switching to protected mode. That means 217 * DF in particular (even though we have cleared it earlier after copying the 218 * command line) because GCC expects it. 219 */ 220 pushl $0 221 popfl 222 223/* 224 * New page tables may be in 4Mbyte page mode and may be using the global pages. 225 * 226 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists 227 * if and only if CPUID exists and has flags other than the FPU flag set. 228 */ 229 movl $-1,pa(X86_CPUID) # preset CPUID level 230 movl $X86_EFLAGS_ID,%ecx 231 pushl %ecx 232 popfl # set EFLAGS=ID 233 pushfl 234 popl %eax # get EFLAGS 235 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set? 236 jz .Lenable_paging # hw disallowed setting of ID bit 237 # which means no CPUID and no CR4 238 239 xorl %eax,%eax 240 cpuid 241 movl %eax,pa(X86_CPUID) # save largest std CPUID function 242 243 movl $1,%eax 244 cpuid 245 andl $~1,%edx # Ignore CPUID.FPU 246 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4 247 248 movl pa(mmu_cr4_features),%eax 249 movl %eax,%cr4 250 251 testb $X86_CR4_PAE, %al # check if PAE is enabled 252 jz .Lenable_paging 253 254 /* Check if extended functions are implemented */ 255 movl $0x80000000, %eax 256 cpuid 257 /* Value must be in the range 0x80000001 to 0x8000ffff */ 258 subl $0x80000001, %eax 259 cmpl $(0x8000ffff-0x80000001), %eax 260 ja .Lenable_paging 261 262 /* Clear bogus XD_DISABLE bits */ 263 call verify_cpu 264 265 mov $0x80000001, %eax 266 cpuid 267 /* Execute Disable bit supported? */ 268 btl $(X86_FEATURE_NX & 31), %edx 269 jnc .Lenable_paging 270 271 /* Setup EFER (Extended Feature Enable Register) */ 272 movl $MSR_EFER, %ecx 273 rdmsr 274 275 btsl $_EFER_NX, %eax 276 /* Make changes effective */ 277 wrmsr 278 279.Lenable_paging: 280 281/* 282 * Enable paging 283 */ 284 movl $pa(initial_page_table), %eax 285 movl %eax,%cr3 /* set the page table pointer.. */ 286 movl $CR0_STATE,%eax 287 movl %eax,%cr0 /* ..and set paging (PG) bit */ 288 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ 2891: 290 /* Shift the stack pointer to a virtual address */ 291 addl $__PAGE_OFFSET, %esp 292 293/* 294 * start system 32-bit setup. We need to re-do some of the things done 295 * in 16-bit mode for the "real" operations. 296 */ 297 movl setup_once_ref,%eax 298 andl %eax,%eax 299 jz 1f # Did we do this already? 300 call *%eax 3011: 302 303/* 304 * Check if it is 486 305 */ 306 movb $4,X86 # at least 486 307 cmpl $-1,X86_CPUID 308 je .Lis486 309 310 /* get vendor info */ 311 xorl %eax,%eax # call CPUID with 0 -> return vendor ID 312 cpuid 313 movl %eax,X86_CPUID # save CPUID level 314 movl %ebx,X86_VENDOR_ID # lo 4 chars 315 movl %edx,X86_VENDOR_ID+4 # next 4 chars 316 movl %ecx,X86_VENDOR_ID+8 # last 4 chars 317 318 orl %eax,%eax # do we have processor info as well? 319 je .Lis486 320 321 movl $1,%eax # Use the CPUID instruction to get CPU type 322 cpuid 323 movb %al,%cl # save reg for future use 324 andb $0x0f,%ah # mask processor family 325 movb %ah,X86 326 andb $0xf0,%al # mask model 327 shrb $4,%al 328 movb %al,X86_MODEL 329 andb $0x0f,%cl # mask mask revision 330 movb %cl,X86_STEPPING 331 movl %edx,X86_CAPABILITY 332 333.Lis486: 334 movl $0x50022,%ecx # set AM, WP, NE and MP 335 movl %cr0,%eax 336 andl $0x80000011,%eax # Save PG,PE,ET 337 orl %ecx,%eax 338 movl %eax,%cr0 339 340 lgdt early_gdt_descr 341 ljmp $(__KERNEL_CS),$1f 3421: movl $(__KERNEL_DS),%eax # reload all the segment registers 343 movl %eax,%ss # after changing gdt. 344 345 movl $(__USER_DS),%eax # DS/ES contains default USER segment 346 movl %eax,%ds 347 movl %eax,%es 348 349 movl $(__KERNEL_PERCPU), %eax 350 movl %eax,%fs # set this cpu's percpu 351 352 movl $(__KERNEL_STACK_CANARY),%eax 353 movl %eax,%gs 354 355 xorl %eax,%eax # Clear LDT 356 lldt %ax 357 358 call *(initial_code) 3591: jmp 1b 360SYM_FUNC_END(startup_32_smp) 361 362#include "verify_cpu.S" 363 364/* 365 * setup_once 366 * 367 * The setup work we only want to run on the BSP. 368 * 369 * Warning: %esi is live across this function. 370 */ 371__INIT 372setup_once: 373#ifdef CONFIG_STACKPROTECTOR 374 /* 375 * Configure the stack canary. The linker can't handle this by 376 * relocation. Manually set base address in stack canary 377 * segment descriptor. 378 */ 379 movl $gdt_page,%eax 380 movl $stack_canary,%ecx 381 movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax) 382 shrl $16, %ecx 383 movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax) 384 movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax) 385#endif 386 387 andl $0,setup_once_ref /* Once is enough, thanks */ 388 ret 389 390SYM_FUNC_START(early_idt_handler_array) 391 # 36(%esp) %eflags 392 # 32(%esp) %cs 393 # 28(%esp) %eip 394 # 24(%rsp) error code 395 i = 0 396 .rept NUM_EXCEPTION_VECTORS 397 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 398 pushl $0 # Dummy error code, to make stack frame uniform 399 .endif 400 pushl $i # 20(%esp) Vector number 401 jmp early_idt_handler_common 402 i = i + 1 403 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 404 .endr 405SYM_FUNC_END(early_idt_handler_array) 406 407SYM_CODE_START_LOCAL(early_idt_handler_common) 408 /* 409 * The stack is the hardware frame, an error code or zero, and the 410 * vector number. 411 */ 412 cld 413 414 incl %ss:early_recursion_flag 415 416 /* The vector number is in pt_regs->gs */ 417 418 cld 419 pushl %fs /* pt_regs->fs (__fsh varies by model) */ 420 pushl %es /* pt_regs->es (__esh varies by model) */ 421 pushl %ds /* pt_regs->ds (__dsh varies by model) */ 422 pushl %eax /* pt_regs->ax */ 423 pushl %ebp /* pt_regs->bp */ 424 pushl %edi /* pt_regs->di */ 425 pushl %esi /* pt_regs->si */ 426 pushl %edx /* pt_regs->dx */ 427 pushl %ecx /* pt_regs->cx */ 428 pushl %ebx /* pt_regs->bx */ 429 430 /* Fix up DS and ES */ 431 movl $(__KERNEL_DS), %ecx 432 movl %ecx, %ds 433 movl %ecx, %es 434 435 /* Load the vector number into EDX */ 436 movl PT_GS(%esp), %edx 437 438 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ 439 movw %gs, PT_GS(%esp) 440 441 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ 442 call early_fixup_exception 443 444 popl %ebx /* pt_regs->bx */ 445 popl %ecx /* pt_regs->cx */ 446 popl %edx /* pt_regs->dx */ 447 popl %esi /* pt_regs->si */ 448 popl %edi /* pt_regs->di */ 449 popl %ebp /* pt_regs->bp */ 450 popl %eax /* pt_regs->ax */ 451 popl %ds /* pt_regs->ds (always ignores __dsh) */ 452 popl %es /* pt_regs->es (always ignores __esh) */ 453 popl %fs /* pt_regs->fs (always ignores __fsh) */ 454 popl %gs /* pt_regs->gs (always ignores __gsh) */ 455 decl %ss:early_recursion_flag 456 addl $4, %esp /* pop pt_regs->orig_ax */ 457 iret 458SYM_CODE_END(early_idt_handler_common) 459 460/* This is the default interrupt "handler" :-) */ 461SYM_FUNC_START(early_ignore_irq) 462 cld 463#ifdef CONFIG_PRINTK 464 pushl %eax 465 pushl %ecx 466 pushl %edx 467 pushl %es 468 pushl %ds 469 movl $(__KERNEL_DS),%eax 470 movl %eax,%ds 471 movl %eax,%es 472 cmpl $2,early_recursion_flag 473 je hlt_loop 474 incl early_recursion_flag 475 pushl 16(%esp) 476 pushl 24(%esp) 477 pushl 32(%esp) 478 pushl 40(%esp) 479 pushl $int_msg 480 call printk 481 482 call dump_stack 483 484 addl $(5*4),%esp 485 popl %ds 486 popl %es 487 popl %edx 488 popl %ecx 489 popl %eax 490#endif 491 iret 492 493hlt_loop: 494 hlt 495 jmp hlt_loop 496SYM_FUNC_END(early_ignore_irq) 497 498__INITDATA 499 .align 4 500SYM_DATA(early_recursion_flag, .long 0) 501 502__REFDATA 503 .align 4 504SYM_DATA(initial_code, .long i386_start_kernel) 505SYM_DATA(setup_once_ref, .long setup_once) 506 507#ifdef CONFIG_PAGE_TABLE_ISOLATION 508#define PGD_ALIGN (2 * PAGE_SIZE) 509#define PTI_USER_PGD_FILL 1024 510#else 511#define PGD_ALIGN (PAGE_SIZE) 512#define PTI_USER_PGD_FILL 0 513#endif 514/* 515 * BSS section 516 */ 517__PAGE_ALIGNED_BSS 518 .align PGD_ALIGN 519#ifdef CONFIG_X86_PAE 520.globl initial_pg_pmd 521initial_pg_pmd: 522 .fill 1024*KPMDS,4,0 523#else 524.globl initial_page_table 525initial_page_table: 526 .fill 1024,4,0 527#endif 528 .align PGD_ALIGN 529initial_pg_fixmap: 530 .fill 1024,4,0 531.globl swapper_pg_dir 532 .align PGD_ALIGN 533swapper_pg_dir: 534 .fill 1024,4,0 535 .fill PTI_USER_PGD_FILL,4,0 536.globl empty_zero_page 537empty_zero_page: 538 .fill 4096,1,0 539EXPORT_SYMBOL(empty_zero_page) 540 541/* 542 * This starts the data section. 543 */ 544#ifdef CONFIG_X86_PAE 545__PAGE_ALIGNED_DATA 546 /* Page-aligned for the benefit of paravirt? */ 547 .align PGD_ALIGN 548SYM_DATA_START(initial_page_table) 549 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */ 550# if KPMDS == 3 551 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 552 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 553 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0 554# elif KPMDS == 2 555 .long 0,0 556 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 557 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 558# elif KPMDS == 1 559 .long 0,0 560 .long 0,0 561 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 562# else 563# error "Kernel PMDs should be 1, 2 or 3" 564# endif 565 .align PAGE_SIZE /* needs to be page-sized too */ 566 567#ifdef CONFIG_PAGE_TABLE_ISOLATION 568 /* 569 * PTI needs another page so sync_initial_pagetable() works correctly 570 * and does not scribble over the data which is placed behind the 571 * actual initial_page_table. See clone_pgd_range(). 572 */ 573 .fill 1024, 4, 0 574#endif 575 576SYM_DATA_END(initial_page_table) 577#endif 578 579.data 580.balign 4 581/* 582 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder 583 * reliably detect the end of the stack. 584 */ 585SYM_DATA(initial_stack, 586 .long init_thread_union + THREAD_SIZE - 587 SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING) 588 589__INITRODATA 590int_msg: 591 .asciz "Unknown interrupt or fault at: %p %p %p\n" 592 593#include "../../x86/xen/xen-head.S" 594 595/* 596 * The IDT and GDT 'descriptors' are a strange 48-bit object 597 * only used by the lidt and lgdt instructions. They are not 598 * like usual segment descriptors - they consist of a 16-bit 599 * segment size, and 32-bit linear address value: 600 */ 601 602 .data 603 ALIGN 604# early boot GDT descriptor (must use 1:1 address mapping) 605 .word 0 # 32 bit align gdt_desc.address 606SYM_DATA_START_LOCAL(boot_gdt_descr) 607 .word __BOOT_DS+7 608 .long boot_gdt - __PAGE_OFFSET 609SYM_DATA_END(boot_gdt_descr) 610 611# boot GDT descriptor (later on used by CPU#0): 612 .word 0 # 32 bit align gdt_desc.address 613SYM_DATA_START(early_gdt_descr) 614 .word GDT_ENTRIES*8-1 615 .long gdt_page /* Overwritten for secondary CPUs */ 616SYM_DATA_END(early_gdt_descr) 617 618/* 619 * The boot_gdt must mirror the equivalent in setup.S and is 620 * used only for booting. 621 */ 622 .align L1_CACHE_BYTES 623SYM_DATA_START(boot_gdt) 624 .fill GDT_ENTRY_BOOT_CS,8,0 625 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ 626 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ 627SYM_DATA_END(boot_gdt) 628