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/* 142 * Non-boot CPU entry point; entered from trampoline.S 143 * We can't lgdt here, because lgdt itself uses a data segment, but 144 * we know the trampoline has already loaded the boot_gdt for us. 145 * 146 * If cpu hotplug is not supported then this code can go in init section 147 * which will be freed later 148 */ 149SYM_FUNC_START(startup_32_smp) 150 cld 151 movl $(__BOOT_DS),%eax 152 movl %eax,%ds 153 movl %eax,%es 154 movl %eax,%fs 155 movl %eax,%gs 156 movl pa(initial_stack),%ecx 157 movl %eax,%ss 158 leal -__PAGE_OFFSET(%ecx),%esp 159 160#ifdef CONFIG_MICROCODE 161 /* Early load ucode on AP. */ 162 call load_ucode_ap 163#endif 164 165.Ldefault_entry: 166 movl $(CR0_STATE & ~X86_CR0_PG),%eax 167 movl %eax,%cr0 168 169/* 170 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave 171 * bits like NT set. This would confuse the debugger if this code is traced. So 172 * initialize them properly now before switching to protected mode. That means 173 * DF in particular (even though we have cleared it earlier after copying the 174 * command line) because GCC expects it. 175 */ 176 pushl $0 177 popfl 178 179/* 180 * New page tables may be in 4Mbyte page mode and may be using the global pages. 181 * 182 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists 183 * if and only if CPUID exists and has flags other than the FPU flag set. 184 */ 185 movl $-1,pa(X86_CPUID) # preset CPUID level 186 movl $X86_EFLAGS_ID,%ecx 187 pushl %ecx 188 popfl # set EFLAGS=ID 189 pushfl 190 popl %eax # get EFLAGS 191 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set? 192 jz .Lenable_paging # hw disallowed setting of ID bit 193 # which means no CPUID and no CR4 194 195 xorl %eax,%eax 196 cpuid 197 movl %eax,pa(X86_CPUID) # save largest std CPUID function 198 199 movl $1,%eax 200 cpuid 201 andl $~1,%edx # Ignore CPUID.FPU 202 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4 203 204 movl pa(mmu_cr4_features),%eax 205 movl %eax,%cr4 206 207 testb $X86_CR4_PAE, %al # check if PAE is enabled 208 jz .Lenable_paging 209 210 /* Check if extended functions are implemented */ 211 movl $0x80000000, %eax 212 cpuid 213 /* Value must be in the range 0x80000001 to 0x8000ffff */ 214 subl $0x80000001, %eax 215 cmpl $(0x8000ffff-0x80000001), %eax 216 ja .Lenable_paging 217 218 /* Clear bogus XD_DISABLE bits */ 219 call verify_cpu 220 221 mov $0x80000001, %eax 222 cpuid 223 /* Execute Disable bit supported? */ 224 btl $(X86_FEATURE_NX & 31), %edx 225 jnc .Lenable_paging 226 227 /* Setup EFER (Extended Feature Enable Register) */ 228 movl $MSR_EFER, %ecx 229 rdmsr 230 231 btsl $_EFER_NX, %eax 232 /* Make changes effective */ 233 wrmsr 234 235.Lenable_paging: 236 237/* 238 * Enable paging 239 */ 240 movl $pa(initial_page_table), %eax 241 movl %eax,%cr3 /* set the page table pointer.. */ 242 movl $CR0_STATE,%eax 243 movl %eax,%cr0 /* ..and set paging (PG) bit */ 244 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ 2451: 246 /* Shift the stack pointer to a virtual address */ 247 addl $__PAGE_OFFSET, %esp 248 249/* 250 * Check if it is 486 251 */ 252 movb $4,X86 # at least 486 253 cmpl $-1,X86_CPUID 254 je .Lis486 255 256 /* get vendor info */ 257 xorl %eax,%eax # call CPUID with 0 -> return vendor ID 258 cpuid 259 movl %eax,X86_CPUID # save CPUID level 260 movl %ebx,X86_VENDOR_ID # lo 4 chars 261 movl %edx,X86_VENDOR_ID+4 # next 4 chars 262 movl %ecx,X86_VENDOR_ID+8 # last 4 chars 263 264 orl %eax,%eax # do we have processor info as well? 265 je .Lis486 266 267 movl $1,%eax # Use the CPUID instruction to get CPU type 268 cpuid 269 movb %al,%cl # save reg for future use 270 andb $0x0f,%ah # mask processor family 271 movb %ah,X86 272 andb $0xf0,%al # mask model 273 shrb $4,%al 274 movb %al,X86_MODEL 275 andb $0x0f,%cl # mask mask revision 276 movb %cl,X86_STEPPING 277 movl %edx,X86_CAPABILITY 278 279.Lis486: 280 movl $0x50022,%ecx # set AM, WP, NE and MP 281 movl %cr0,%eax 282 andl $0x80000011,%eax # Save PG,PE,ET 283 orl %ecx,%eax 284 movl %eax,%cr0 285 286 lgdt early_gdt_descr 287 ljmp $(__KERNEL_CS),$1f 2881: movl $(__KERNEL_DS),%eax # reload all the segment registers 289 movl %eax,%ss # after changing gdt. 290 291 movl $(__USER_DS),%eax # DS/ES contains default USER segment 292 movl %eax,%ds 293 movl %eax,%es 294 295 movl $(__KERNEL_PERCPU), %eax 296 movl %eax,%fs # set this cpu's percpu 297 298 xorl %eax,%eax 299 movl %eax,%gs # clear possible garbage in %gs 300 301 xorl %eax,%eax # Clear LDT 302 lldt %ax 303 304 call *(initial_code) 3051: jmp 1b 306SYM_FUNC_END(startup_32_smp) 307 308#include "verify_cpu.S" 309 310__INIT 311SYM_FUNC_START(early_idt_handler_array) 312 # 36(%esp) %eflags 313 # 32(%esp) %cs 314 # 28(%esp) %eip 315 # 24(%rsp) error code 316 i = 0 317 .rept NUM_EXCEPTION_VECTORS 318 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 319 pushl $0 # Dummy error code, to make stack frame uniform 320 .endif 321 pushl $i # 20(%esp) Vector number 322 jmp early_idt_handler_common 323 i = i + 1 324 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 325 .endr 326SYM_FUNC_END(early_idt_handler_array) 327 328SYM_CODE_START_LOCAL(early_idt_handler_common) 329 /* 330 * The stack is the hardware frame, an error code or zero, and the 331 * vector number. 332 */ 333 cld 334 335 incl %ss:early_recursion_flag 336 337 /* The vector number is in pt_regs->gs */ 338 339 cld 340 pushl %fs /* pt_regs->fs (__fsh varies by model) */ 341 pushl %es /* pt_regs->es (__esh varies by model) */ 342 pushl %ds /* pt_regs->ds (__dsh varies by model) */ 343 pushl %eax /* pt_regs->ax */ 344 pushl %ebp /* pt_regs->bp */ 345 pushl %edi /* pt_regs->di */ 346 pushl %esi /* pt_regs->si */ 347 pushl %edx /* pt_regs->dx */ 348 pushl %ecx /* pt_regs->cx */ 349 pushl %ebx /* pt_regs->bx */ 350 351 /* Fix up DS and ES */ 352 movl $(__KERNEL_DS), %ecx 353 movl %ecx, %ds 354 movl %ecx, %es 355 356 /* Load the vector number into EDX */ 357 movl PT_GS(%esp), %edx 358 359 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ 360 movw %gs, PT_GS(%esp) 361 362 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ 363 call early_fixup_exception 364 365 popl %ebx /* pt_regs->bx */ 366 popl %ecx /* pt_regs->cx */ 367 popl %edx /* pt_regs->dx */ 368 popl %esi /* pt_regs->si */ 369 popl %edi /* pt_regs->di */ 370 popl %ebp /* pt_regs->bp */ 371 popl %eax /* pt_regs->ax */ 372 popl %ds /* pt_regs->ds (always ignores __dsh) */ 373 popl %es /* pt_regs->es (always ignores __esh) */ 374 popl %fs /* pt_regs->fs (always ignores __fsh) */ 375 popl %gs /* pt_regs->gs (always ignores __gsh) */ 376 decl %ss:early_recursion_flag 377 addl $4, %esp /* pop pt_regs->orig_ax */ 378 iret 379SYM_CODE_END(early_idt_handler_common) 380 381/* This is the default interrupt "handler" :-) */ 382SYM_FUNC_START(early_ignore_irq) 383 cld 384#ifdef CONFIG_PRINTK 385 pushl %eax 386 pushl %ecx 387 pushl %edx 388 pushl %es 389 pushl %ds 390 movl $(__KERNEL_DS),%eax 391 movl %eax,%ds 392 movl %eax,%es 393 cmpl $2,early_recursion_flag 394 je hlt_loop 395 incl early_recursion_flag 396 pushl 16(%esp) 397 pushl 24(%esp) 398 pushl 32(%esp) 399 pushl 40(%esp) 400 pushl $int_msg 401 call _printk 402 403 call dump_stack 404 405 addl $(5*4),%esp 406 popl %ds 407 popl %es 408 popl %edx 409 popl %ecx 410 popl %eax 411#endif 412 iret 413 414hlt_loop: 415 hlt 416 jmp hlt_loop 417SYM_FUNC_END(early_ignore_irq) 418 419__INITDATA 420 .align 4 421SYM_DATA(early_recursion_flag, .long 0) 422 423__REFDATA 424 .align 4 425SYM_DATA(initial_code, .long i386_start_kernel) 426 427#ifdef CONFIG_PAGE_TABLE_ISOLATION 428#define PGD_ALIGN (2 * PAGE_SIZE) 429#define PTI_USER_PGD_FILL 1024 430#else 431#define PGD_ALIGN (PAGE_SIZE) 432#define PTI_USER_PGD_FILL 0 433#endif 434/* 435 * BSS section 436 */ 437__PAGE_ALIGNED_BSS 438 .align PGD_ALIGN 439#ifdef CONFIG_X86_PAE 440.globl initial_pg_pmd 441initial_pg_pmd: 442 .fill 1024*KPMDS,4,0 443#else 444.globl initial_page_table 445initial_page_table: 446 .fill 1024,4,0 447#endif 448 .align PGD_ALIGN 449initial_pg_fixmap: 450 .fill 1024,4,0 451.globl swapper_pg_dir 452 .align PGD_ALIGN 453swapper_pg_dir: 454 .fill 1024,4,0 455 .fill PTI_USER_PGD_FILL,4,0 456.globl empty_zero_page 457empty_zero_page: 458 .fill 4096,1,0 459EXPORT_SYMBOL(empty_zero_page) 460 461/* 462 * This starts the data section. 463 */ 464#ifdef CONFIG_X86_PAE 465__PAGE_ALIGNED_DATA 466 /* Page-aligned for the benefit of paravirt? */ 467 .align PGD_ALIGN 468SYM_DATA_START(initial_page_table) 469 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */ 470# if KPMDS == 3 471 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 472 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 473 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0 474# elif KPMDS == 2 475 .long 0,0 476 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 477 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 478# elif KPMDS == 1 479 .long 0,0 480 .long 0,0 481 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 482# else 483# error "Kernel PMDs should be 1, 2 or 3" 484# endif 485 .align PAGE_SIZE /* needs to be page-sized too */ 486 487#ifdef CONFIG_PAGE_TABLE_ISOLATION 488 /* 489 * PTI needs another page so sync_initial_pagetable() works correctly 490 * and does not scribble over the data which is placed behind the 491 * actual initial_page_table. See clone_pgd_range(). 492 */ 493 .fill 1024, 4, 0 494#endif 495 496SYM_DATA_END(initial_page_table) 497#endif 498 499.data 500.balign 4 501/* 502 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder 503 * reliably detect the end of the stack. 504 */ 505SYM_DATA(initial_stack, 506 .long init_thread_union + THREAD_SIZE - 507 SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING) 508 509__INITRODATA 510int_msg: 511 .asciz "Unknown interrupt or fault at: %p %p %p\n" 512 513#include "../../x86/xen/xen-head.S" 514 515/* 516 * The IDT and GDT 'descriptors' are a strange 48-bit object 517 * only used by the lidt and lgdt instructions. They are not 518 * like usual segment descriptors - they consist of a 16-bit 519 * segment size, and 32-bit linear address value: 520 */ 521 522 .data 523 ALIGN 524# early boot GDT descriptor (must use 1:1 address mapping) 525 .word 0 # 32 bit align gdt_desc.address 526SYM_DATA_START_LOCAL(boot_gdt_descr) 527 .word __BOOT_DS+7 528 .long boot_gdt - __PAGE_OFFSET 529SYM_DATA_END(boot_gdt_descr) 530 531# boot GDT descriptor (later on used by CPU#0): 532 .word 0 # 32 bit align gdt_desc.address 533SYM_DATA_START(early_gdt_descr) 534 .word GDT_ENTRIES*8-1 535 .long gdt_page /* Overwritten for secondary CPUs */ 536SYM_DATA_END(early_gdt_descr) 537 538/* 539 * The boot_gdt must mirror the equivalent in setup.S and is 540 * used only for booting. 541 */ 542 .align L1_CACHE_BYTES 543SYM_DATA_START(boot_gdt) 544 .fill GDT_ENTRY_BOOT_CS,8,0 545 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ 546 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ 547SYM_DATA_END(boot_gdt) 548