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/nospec-branch.h> 27#include <asm/bootparam.h> 28#include <asm/export.h> 29#include <asm/pgtable_32.h> 30 31/* Physical address */ 32#define pa(X) ((X) - __PAGE_OFFSET) 33 34/* 35 * References to members of the new_cpu_data structure. 36 */ 37 38#define X86 new_cpu_data+CPUINFO_x86 39#define X86_VENDOR new_cpu_data+CPUINFO_x86_vendor 40#define X86_MODEL new_cpu_data+CPUINFO_x86_model 41#define X86_STEPPING new_cpu_data+CPUINFO_x86_stepping 42#define X86_HARD_MATH new_cpu_data+CPUINFO_hard_math 43#define X86_CPUID new_cpu_data+CPUINFO_cpuid_level 44#define X86_CAPABILITY new_cpu_data+CPUINFO_x86_capability 45#define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id 46 47 48#define SIZEOF_PTREGS 17*4 49 50/* 51 * Worst-case size of the kernel mapping we need to make: 52 * a relocatable kernel can live anywhere in lowmem, so we need to be able 53 * to map all of lowmem. 54 */ 55KERNEL_PAGES = LOWMEM_PAGES 56 57INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE 58RESERVE_BRK(pagetables, INIT_MAP_SIZE) 59 60/* 61 * 32-bit kernel entrypoint; only used by the boot CPU. On entry, 62 * %esi points to the real-mode code as a 32-bit pointer. 63 * CS and DS must be 4 GB flat segments, but we don't depend on 64 * any particular GDT layout, because we load our own as soon as we 65 * can. 66 */ 67__HEAD 68SYM_CODE_START(startup_32) 69 movl pa(initial_stack),%ecx 70 71/* 72 * Set segments to known values. 73 */ 74 lgdt pa(boot_gdt_descr) 75 movl $(__BOOT_DS),%eax 76 movl %eax,%ds 77 movl %eax,%es 78 movl %eax,%fs 79 movl %eax,%gs 80 movl %eax,%ss 81 leal -__PAGE_OFFSET(%ecx),%esp 82 83/* 84 * Clear BSS first so that there are no surprises... 85 */ 86 cld 87 xorl %eax,%eax 88 movl $pa(__bss_start),%edi 89 movl $pa(__bss_stop),%ecx 90 subl %edi,%ecx 91 shrl $2,%ecx 92 rep ; stosl 93/* 94 * Copy bootup parameters out of the way. 95 * Note: %esi still has the pointer to the real-mode data. 96 * With the kexec as boot loader, parameter segment might be loaded beyond 97 * kernel image and might not even be addressable by early boot page tables. 98 * (kexec on panic case). Hence copy out the parameters before initializing 99 * page tables. 100 */ 101 movl $pa(boot_params),%edi 102 movl $(PARAM_SIZE/4),%ecx 103 cld 104 rep 105 movsl 106 movl pa(boot_params) + NEW_CL_POINTER,%esi 107 andl %esi,%esi 108 jz 1f # No command line 109 movl $pa(boot_command_line),%edi 110 movl $(COMMAND_LINE_SIZE/4),%ecx 111 rep 112 movsl 1131: 114 115#ifdef CONFIG_OLPC 116 /* save OFW's pgdir table for later use when calling into OFW */ 117 movl %cr3, %eax 118 movl %eax, pa(olpc_ofw_pgd) 119#endif 120 121#ifdef CONFIG_MICROCODE 122 /* Early load ucode on BSP. */ 123 call load_ucode_bsp 124#endif 125 126 /* Create early pagetables. */ 127 call mk_early_pgtbl_32 128 129 /* Do early initialization of the fixmap area */ 130 movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax 131#ifdef CONFIG_X86_PAE 132#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ 133 movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) 134#else 135 movl %eax,pa(initial_page_table+0xffc) 136#endif 137 138 jmp .Ldefault_entry 139SYM_CODE_END(startup_32) 140 141#ifdef CONFIG_HOTPLUG_CPU 142/* 143 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set 144 * up already except stack. We just set up stack here. Then call 145 * start_secondary(). 146 */ 147SYM_FUNC_START(start_cpu0) 148 movl initial_stack, %ecx 149 movl %ecx, %esp 150 call *(initial_code) 1511: jmp 1b 152SYM_FUNC_END(start_cpu0) 153#endif 154 155/* 156 * Non-boot CPU entry point; entered from trampoline.S 157 * We can't lgdt here, because lgdt itself uses a data segment, but 158 * we know the trampoline has already loaded the boot_gdt for us. 159 * 160 * If cpu hotplug is not supported then this code can go in init section 161 * which will be freed later 162 */ 163SYM_FUNC_START(startup_32_smp) 164 cld 165 movl $(__BOOT_DS),%eax 166 movl %eax,%ds 167 movl %eax,%es 168 movl %eax,%fs 169 movl %eax,%gs 170 movl pa(initial_stack),%ecx 171 movl %eax,%ss 172 leal -__PAGE_OFFSET(%ecx),%esp 173 174#ifdef CONFIG_MICROCODE 175 /* Early load ucode on AP. */ 176 call load_ucode_ap 177#endif 178 179.Ldefault_entry: 180 movl $(CR0_STATE & ~X86_CR0_PG),%eax 181 movl %eax,%cr0 182 183/* 184 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave 185 * bits like NT set. This would confuse the debugger if this code is traced. So 186 * initialize them properly now before switching to protected mode. That means 187 * DF in particular (even though we have cleared it earlier after copying the 188 * command line) because GCC expects it. 189 */ 190 pushl $0 191 popfl 192 193/* 194 * New page tables may be in 4Mbyte page mode and may be using the global pages. 195 * 196 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists 197 * if and only if CPUID exists and has flags other than the FPU flag set. 198 */ 199 movl $-1,pa(X86_CPUID) # preset CPUID level 200 movl $X86_EFLAGS_ID,%ecx 201 pushl %ecx 202 popfl # set EFLAGS=ID 203 pushfl 204 popl %eax # get EFLAGS 205 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set? 206 jz .Lenable_paging # hw disallowed setting of ID bit 207 # which means no CPUID and no CR4 208 209 xorl %eax,%eax 210 cpuid 211 movl %eax,pa(X86_CPUID) # save largest std CPUID function 212 213 movl $1,%eax 214 cpuid 215 andl $~1,%edx # Ignore CPUID.FPU 216 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4 217 218 movl pa(mmu_cr4_features),%eax 219 movl %eax,%cr4 220 221 testb $X86_CR4_PAE, %al # check if PAE is enabled 222 jz .Lenable_paging 223 224 /* Check if extended functions are implemented */ 225 movl $0x80000000, %eax 226 cpuid 227 /* Value must be in the range 0x80000001 to 0x8000ffff */ 228 subl $0x80000001, %eax 229 cmpl $(0x8000ffff-0x80000001), %eax 230 ja .Lenable_paging 231 232 /* Clear bogus XD_DISABLE bits */ 233 call verify_cpu 234 235 mov $0x80000001, %eax 236 cpuid 237 /* Execute Disable bit supported? */ 238 btl $(X86_FEATURE_NX & 31), %edx 239 jnc .Lenable_paging 240 241 /* Setup EFER (Extended Feature Enable Register) */ 242 movl $MSR_EFER, %ecx 243 rdmsr 244 245 btsl $_EFER_NX, %eax 246 /* Make changes effective */ 247 wrmsr 248 249.Lenable_paging: 250 251/* 252 * Enable paging 253 */ 254 movl $pa(initial_page_table), %eax 255 movl %eax,%cr3 /* set the page table pointer.. */ 256 movl $CR0_STATE,%eax 257 movl %eax,%cr0 /* ..and set paging (PG) bit */ 258 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ 2591: 260 /* Shift the stack pointer to a virtual address */ 261 addl $__PAGE_OFFSET, %esp 262 263/* 264 * Check if it is 486 265 */ 266 movb $4,X86 # at least 486 267 cmpl $-1,X86_CPUID 268 je .Lis486 269 270 /* get vendor info */ 271 xorl %eax,%eax # call CPUID with 0 -> return vendor ID 272 cpuid 273 movl %eax,X86_CPUID # save CPUID level 274 movl %ebx,X86_VENDOR_ID # lo 4 chars 275 movl %edx,X86_VENDOR_ID+4 # next 4 chars 276 movl %ecx,X86_VENDOR_ID+8 # last 4 chars 277 278 orl %eax,%eax # do we have processor info as well? 279 je .Lis486 280 281 movl $1,%eax # Use the CPUID instruction to get CPU type 282 cpuid 283 movb %al,%cl # save reg for future use 284 andb $0x0f,%ah # mask processor family 285 movb %ah,X86 286 andb $0xf0,%al # mask model 287 shrb $4,%al 288 movb %al,X86_MODEL 289 andb $0x0f,%cl # mask mask revision 290 movb %cl,X86_STEPPING 291 movl %edx,X86_CAPABILITY 292 293.Lis486: 294 movl $0x50022,%ecx # set AM, WP, NE and MP 295 movl %cr0,%eax 296 andl $0x80000011,%eax # Save PG,PE,ET 297 orl %ecx,%eax 298 movl %eax,%cr0 299 300 lgdt early_gdt_descr 301 ljmp $(__KERNEL_CS),$1f 3021: movl $(__KERNEL_DS),%eax # reload all the segment registers 303 movl %eax,%ss # after changing gdt. 304 305 movl $(__USER_DS),%eax # DS/ES contains default USER segment 306 movl %eax,%ds 307 movl %eax,%es 308 309 movl $(__KERNEL_PERCPU), %eax 310 movl %eax,%fs # set this cpu's percpu 311 312 xorl %eax,%eax 313 movl %eax,%gs # clear possible garbage in %gs 314 315 xorl %eax,%eax # Clear LDT 316 lldt %ax 317 318 call *(initial_code) 3191: jmp 1b 320SYM_FUNC_END(startup_32_smp) 321 322#include "verify_cpu.S" 323 324__INIT 325SYM_FUNC_START(early_idt_handler_array) 326 # 36(%esp) %eflags 327 # 32(%esp) %cs 328 # 28(%esp) %eip 329 # 24(%rsp) error code 330 i = 0 331 .rept NUM_EXCEPTION_VECTORS 332 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 333 pushl $0 # Dummy error code, to make stack frame uniform 334 .endif 335 pushl $i # 20(%esp) Vector number 336 jmp early_idt_handler_common 337 i = i + 1 338 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 339 .endr 340SYM_FUNC_END(early_idt_handler_array) 341 342SYM_CODE_START_LOCAL(early_idt_handler_common) 343 /* 344 * The stack is the hardware frame, an error code or zero, and the 345 * vector number. 346 */ 347 cld 348 349 incl %ss:early_recursion_flag 350 351 /* The vector number is in pt_regs->gs */ 352 353 cld 354 pushl %fs /* pt_regs->fs (__fsh varies by model) */ 355 pushl %es /* pt_regs->es (__esh varies by model) */ 356 pushl %ds /* pt_regs->ds (__dsh varies by model) */ 357 pushl %eax /* pt_regs->ax */ 358 pushl %ebp /* pt_regs->bp */ 359 pushl %edi /* pt_regs->di */ 360 pushl %esi /* pt_regs->si */ 361 pushl %edx /* pt_regs->dx */ 362 pushl %ecx /* pt_regs->cx */ 363 pushl %ebx /* pt_regs->bx */ 364 365 /* Fix up DS and ES */ 366 movl $(__KERNEL_DS), %ecx 367 movl %ecx, %ds 368 movl %ecx, %es 369 370 /* Load the vector number into EDX */ 371 movl PT_GS(%esp), %edx 372 373 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ 374 movw %gs, PT_GS(%esp) 375 376 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ 377 call early_fixup_exception 378 379 popl %ebx /* pt_regs->bx */ 380 popl %ecx /* pt_regs->cx */ 381 popl %edx /* pt_regs->dx */ 382 popl %esi /* pt_regs->si */ 383 popl %edi /* pt_regs->di */ 384 popl %ebp /* pt_regs->bp */ 385 popl %eax /* pt_regs->ax */ 386 popl %ds /* pt_regs->ds (always ignores __dsh) */ 387 popl %es /* pt_regs->es (always ignores __esh) */ 388 popl %fs /* pt_regs->fs (always ignores __fsh) */ 389 popl %gs /* pt_regs->gs (always ignores __gsh) */ 390 decl %ss:early_recursion_flag 391 addl $4, %esp /* pop pt_regs->orig_ax */ 392 iret 393SYM_CODE_END(early_idt_handler_common) 394 395/* This is the default interrupt "handler" :-) */ 396SYM_FUNC_START(early_ignore_irq) 397 cld 398#ifdef CONFIG_PRINTK 399 pushl %eax 400 pushl %ecx 401 pushl %edx 402 pushl %es 403 pushl %ds 404 movl $(__KERNEL_DS),%eax 405 movl %eax,%ds 406 movl %eax,%es 407 cmpl $2,early_recursion_flag 408 je hlt_loop 409 incl early_recursion_flag 410 pushl 16(%esp) 411 pushl 24(%esp) 412 pushl 32(%esp) 413 pushl 40(%esp) 414 pushl $int_msg 415 call _printk 416 417 call dump_stack 418 419 addl $(5*4),%esp 420 popl %ds 421 popl %es 422 popl %edx 423 popl %ecx 424 popl %eax 425#endif 426 iret 427 428hlt_loop: 429 hlt 430 jmp hlt_loop 431SYM_FUNC_END(early_ignore_irq) 432 433__INITDATA 434 .align 4 435SYM_DATA(early_recursion_flag, .long 0) 436 437__REFDATA 438 .align 4 439SYM_DATA(initial_code, .long i386_start_kernel) 440 441#ifdef CONFIG_PAGE_TABLE_ISOLATION 442#define PGD_ALIGN (2 * PAGE_SIZE) 443#define PTI_USER_PGD_FILL 1024 444#else 445#define PGD_ALIGN (PAGE_SIZE) 446#define PTI_USER_PGD_FILL 0 447#endif 448/* 449 * BSS section 450 */ 451__PAGE_ALIGNED_BSS 452 .align PGD_ALIGN 453#ifdef CONFIG_X86_PAE 454.globl initial_pg_pmd 455initial_pg_pmd: 456 .fill 1024*KPMDS,4,0 457#else 458.globl initial_page_table 459initial_page_table: 460 .fill 1024,4,0 461#endif 462 .align PGD_ALIGN 463initial_pg_fixmap: 464 .fill 1024,4,0 465.globl swapper_pg_dir 466 .align PGD_ALIGN 467swapper_pg_dir: 468 .fill 1024,4,0 469 .fill PTI_USER_PGD_FILL,4,0 470.globl empty_zero_page 471empty_zero_page: 472 .fill 4096,1,0 473EXPORT_SYMBOL(empty_zero_page) 474 475/* 476 * This starts the data section. 477 */ 478#ifdef CONFIG_X86_PAE 479__PAGE_ALIGNED_DATA 480 /* Page-aligned for the benefit of paravirt? */ 481 .align PGD_ALIGN 482SYM_DATA_START(initial_page_table) 483 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */ 484# if KPMDS == 3 485 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 486 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 487 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0 488# elif KPMDS == 2 489 .long 0,0 490 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 491 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 492# elif KPMDS == 1 493 .long 0,0 494 .long 0,0 495 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 496# else 497# error "Kernel PMDs should be 1, 2 or 3" 498# endif 499 .align PAGE_SIZE /* needs to be page-sized too */ 500 501#ifdef CONFIG_PAGE_TABLE_ISOLATION 502 /* 503 * PTI needs another page so sync_initial_pagetable() works correctly 504 * and does not scribble over the data which is placed behind the 505 * actual initial_page_table. See clone_pgd_range(). 506 */ 507 .fill 1024, 4, 0 508#endif 509 510SYM_DATA_END(initial_page_table) 511#endif 512 513.data 514.balign 4 515/* 516 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder 517 * reliably detect the end of the stack. 518 */ 519SYM_DATA(initial_stack, 520 .long init_thread_union + THREAD_SIZE - 521 SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING) 522 523__INITRODATA 524int_msg: 525 .asciz "Unknown interrupt or fault at: %p %p %p\n" 526 527#include "../../x86/xen/xen-head.S" 528 529/* 530 * The IDT and GDT 'descriptors' are a strange 48-bit object 531 * only used by the lidt and lgdt instructions. They are not 532 * like usual segment descriptors - they consist of a 16-bit 533 * segment size, and 32-bit linear address value: 534 */ 535 536 .data 537 ALIGN 538# early boot GDT descriptor (must use 1:1 address mapping) 539 .word 0 # 32 bit align gdt_desc.address 540SYM_DATA_START_LOCAL(boot_gdt_descr) 541 .word __BOOT_DS+7 542 .long boot_gdt - __PAGE_OFFSET 543SYM_DATA_END(boot_gdt_descr) 544 545# boot GDT descriptor (later on used by CPU#0): 546 .word 0 # 32 bit align gdt_desc.address 547SYM_DATA_START(early_gdt_descr) 548 .word GDT_ENTRIES*8-1 549 .long gdt_page /* Overwritten for secondary CPUs */ 550SYM_DATA_END(early_gdt_descr) 551 552/* 553 * The boot_gdt must mirror the equivalent in setup.S and is 554 * used only for booting. 555 */ 556 .align L1_CACHE_BYTES 557SYM_DATA_START(boot_gdt) 558 .fill GDT_ENTRY_BOOT_CS,8,0 559 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ 560 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ 561SYM_DATA_END(boot_gdt) 562