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/export.h> 12#include <linux/threads.h> 13#include <linux/init.h> 14#include <linux/linkage.h> 15#include <asm/segment.h> 16#include <asm/page_types.h> 17#include <asm/pgtable_types.h> 18#include <asm/cache.h> 19#include <asm/thread_info.h> 20#include <asm/asm-offsets.h> 21#include <asm/setup.h> 22#include <asm/processor-flags.h> 23#include <asm/msr-index.h> 24#include <asm/cpufeatures.h> 25#include <asm/percpu.h> 26#include <asm/nops.h> 27#include <asm/nospec-branch.h> 28#include <asm/bootparam.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 * Worst-case size of the kernel mapping we need to make: 49 * a relocatable kernel can live anywhere in lowmem, so we need to be able 50 * to map all of lowmem. 51 */ 52KERNEL_PAGES = LOWMEM_PAGES 53 54INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE 55RESERVE_BRK(pagetables, INIT_MAP_SIZE) 56 57/* 58 * 32-bit kernel entrypoint; only used by the boot CPU. On entry, 59 * %esi points to the real-mode code as a 32-bit pointer. 60 * CS and DS must be 4 GB flat segments, but we don't depend on 61 * any particular GDT layout, because we load our own as soon as we 62 * can. 63 */ 64__HEAD 65SYM_CODE_START(startup_32) 66 movl pa(initial_stack),%ecx 67 68/* 69 * Set segments to known values. 70 */ 71 lgdt pa(boot_gdt_descr) 72 movl $(__BOOT_DS),%eax 73 movl %eax,%ds 74 movl %eax,%es 75 movl %eax,%fs 76 movl %eax,%gs 77 movl %eax,%ss 78 leal -__PAGE_OFFSET(%ecx),%esp 79 80/* 81 * Clear BSS first so that there are no surprises... 82 */ 83 cld 84 xorl %eax,%eax 85 movl $pa(__bss_start),%edi 86 movl $pa(__bss_stop),%ecx 87 subl %edi,%ecx 88 shrl $2,%ecx 89 rep stosl 90/* 91 * Copy bootup parameters out of the way. 92 * Note: %esi still has the pointer to the real-mode data. 93 * With the kexec as boot loader, parameter segment might be loaded beyond 94 * kernel image and might not even be addressable by early boot page tables. 95 * (kexec on panic case). Hence copy out the parameters before initializing 96 * page tables. 97 */ 98 movl $pa(boot_params),%edi 99 movl $(PARAM_SIZE/4),%ecx 100 cld 101 rep movsl 102 movl pa(boot_params) + NEW_CL_POINTER,%esi 103 andl %esi,%esi 104 jz 1f # No command line 105 movl $pa(boot_command_line),%edi 106 movl $(COMMAND_LINE_SIZE/4),%ecx 107 rep movsl 1081: 109 110#ifdef CONFIG_OLPC 111 /* save OFW's pgdir table for later use when calling into OFW */ 112 movl %cr3, %eax 113 movl %eax, pa(olpc_ofw_pgd) 114#endif 115 116 /* Create early pagetables. */ 117 call mk_early_pgtbl_32 118 119 /* Do early initialization of the fixmap area */ 120 movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax 121#ifdef CONFIG_X86_PAE 122#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ 123 movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) 124#else 125 movl %eax,pa(initial_page_table+0xffc) 126#endif 127 128 jmp .Ldefault_entry 129SYM_CODE_END(startup_32) 130 131/* 132 * Non-boot CPU entry point; entered from trampoline.S 133 * We can't lgdt here, because lgdt itself uses a data segment, but 134 * we know the trampoline has already loaded the boot_gdt for us. 135 * 136 * If cpu hotplug is not supported then this code can go in init section 137 * which will be freed later 138 */ 139SYM_FUNC_START(startup_32_smp) 140 cld 141 movl $(__BOOT_DS),%eax 142 movl %eax,%ds 143 movl %eax,%es 144 movl %eax,%fs 145 movl %eax,%gs 146 movl pa(initial_stack),%ecx 147 movl %eax,%ss 148 leal -__PAGE_OFFSET(%ecx),%esp 149 150.Ldefault_entry: 151 movl $(CR0_STATE & ~X86_CR0_PG),%eax 152 movl %eax,%cr0 153 154/* 155 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave 156 * bits like NT set. This would confuse the debugger if this code is traced. So 157 * initialize them properly now before switching to protected mode. That means 158 * DF in particular (even though we have cleared it earlier after copying the 159 * command line) because GCC expects it. 160 */ 161 pushl $0 162 popfl 163 164/* 165 * New page tables may be in 4Mbyte page mode and may be using the global pages. 166 * 167 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists 168 * if and only if CPUID exists and has flags other than the FPU flag set. 169 */ 170 movl $-1,pa(X86_CPUID) # preset CPUID level 171 movl $X86_EFLAGS_ID,%ecx 172 pushl %ecx 173 popfl # set EFLAGS=ID 174 pushfl 175 popl %eax # get EFLAGS 176 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set? 177 jz .Lenable_paging # hw disallowed setting of ID bit 178 # which means no CPUID and no CR4 179 180 xorl %eax,%eax 181 cpuid 182 movl %eax,pa(X86_CPUID) # save largest std CPUID function 183 184 movl $1,%eax 185 cpuid 186 andl $~1,%edx # Ignore CPUID.FPU 187 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4 188 189 movl pa(mmu_cr4_features),%eax 190 movl %eax,%cr4 191 192 testb $X86_CR4_PAE, %al # check if PAE is enabled 193 jz .Lenable_paging 194 195 /* Check if extended functions are implemented */ 196 movl $0x80000000, %eax 197 cpuid 198 /* Value must be in the range 0x80000001 to 0x8000ffff */ 199 subl $0x80000001, %eax 200 cmpl $(0x8000ffff-0x80000001), %eax 201 ja .Lenable_paging 202 203 /* Clear bogus XD_DISABLE bits */ 204 call verify_cpu 205 206 mov $0x80000001, %eax 207 cpuid 208 /* Execute Disable bit supported? */ 209 btl $(X86_FEATURE_NX & 31), %edx 210 jnc .Lenable_paging 211 212 /* Setup EFER (Extended Feature Enable Register) */ 213 movl $MSR_EFER, %ecx 214 rdmsr 215 216 btsl $_EFER_NX, %eax 217 /* Make changes effective */ 218 wrmsr 219 220.Lenable_paging: 221 222/* 223 * Enable paging 224 */ 225 movl $pa(initial_page_table), %eax 226 movl %eax,%cr3 /* set the page table pointer.. */ 227 movl $CR0_STATE,%eax 228 movl %eax,%cr0 /* ..and set paging (PG) bit */ 229 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ 2301: 231 /* Shift the stack pointer to a virtual address */ 232 addl $__PAGE_OFFSET, %esp 233 234/* 235 * Check if it is 486 236 */ 237 movb $4,X86 # at least 486 238 cmpl $-1,X86_CPUID 239 je .Lis486 240 241 /* get vendor info */ 242 xorl %eax,%eax # call CPUID with 0 -> return vendor ID 243 cpuid 244 movl %eax,X86_CPUID # save CPUID level 245 movl %ebx,X86_VENDOR_ID # lo 4 chars 246 movl %edx,X86_VENDOR_ID+4 # next 4 chars 247 movl %ecx,X86_VENDOR_ID+8 # last 4 chars 248 249 orl %eax,%eax # do we have processor info as well? 250 je .Lis486 251 252 movl $1,%eax # Use the CPUID instruction to get CPU type 253 cpuid 254 movb %al,%cl # save reg for future use 255 andb $0x0f,%ah # mask processor family 256 movb %ah,X86 257 andb $0xf0,%al # mask model 258 shrb $4,%al 259 movb %al,X86_MODEL 260 andb $0x0f,%cl # mask mask revision 261 movb %cl,X86_STEPPING 262 movl %edx,X86_CAPABILITY 263 264.Lis486: 265 movl $0x50022,%ecx # set AM, WP, NE and MP 266 movl %cr0,%eax 267 andl $0x80000011,%eax # Save PG,PE,ET 268 orl %ecx,%eax 269 movl %eax,%cr0 270 271 lgdt early_gdt_descr 272 ljmp $(__KERNEL_CS),$1f 2731: movl $(__KERNEL_DS),%eax # reload all the segment registers 274 movl %eax,%ss # after changing gdt. 275 276 movl $(__USER_DS),%eax # DS/ES contains default USER segment 277 movl %eax,%ds 278 movl %eax,%es 279 280 movl $(__KERNEL_PERCPU), %eax 281 movl %eax,%fs # set this cpu's percpu 282 283 xorl %eax,%eax 284 movl %eax,%gs # clear possible garbage in %gs 285 286 xorl %eax,%eax # Clear LDT 287 lldt %ax 288 289 call *(initial_code) 2901: jmp 1b 291SYM_FUNC_END(startup_32_smp) 292 293#include "verify_cpu.S" 294 295__INIT 296SYM_FUNC_START(early_idt_handler_array) 297 # 36(%esp) %eflags 298 # 32(%esp) %cs 299 # 28(%esp) %eip 300 # 24(%rsp) error code 301 i = 0 302 .rept NUM_EXCEPTION_VECTORS 303 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 304 pushl $0 # Dummy error code, to make stack frame uniform 305 .endif 306 pushl $i # 20(%esp) Vector number 307 jmp early_idt_handler_common 308 i = i + 1 309 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 310 .endr 311SYM_FUNC_END(early_idt_handler_array) 312 313SYM_CODE_START_LOCAL(early_idt_handler_common) 314 /* 315 * The stack is the hardware frame, an error code or zero, and the 316 * vector number. 317 */ 318 cld 319 320 incl %ss:early_recursion_flag 321 322 /* The vector number is in pt_regs->gs */ 323 324 cld 325 pushl %fs /* pt_regs->fs (__fsh varies by model) */ 326 pushl %es /* pt_regs->es (__esh varies by model) */ 327 pushl %ds /* pt_regs->ds (__dsh varies by model) */ 328 pushl %eax /* pt_regs->ax */ 329 pushl %ebp /* pt_regs->bp */ 330 pushl %edi /* pt_regs->di */ 331 pushl %esi /* pt_regs->si */ 332 pushl %edx /* pt_regs->dx */ 333 pushl %ecx /* pt_regs->cx */ 334 pushl %ebx /* pt_regs->bx */ 335 336 /* Fix up DS and ES */ 337 movl $(__KERNEL_DS), %ecx 338 movl %ecx, %ds 339 movl %ecx, %es 340 341 /* Load the vector number into EDX */ 342 movl PT_GS(%esp), %edx 343 344 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ 345 movw %gs, PT_GS(%esp) 346 347 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ 348 call early_fixup_exception 349 350 popl %ebx /* pt_regs->bx */ 351 popl %ecx /* pt_regs->cx */ 352 popl %edx /* pt_regs->dx */ 353 popl %esi /* pt_regs->si */ 354 popl %edi /* pt_regs->di */ 355 popl %ebp /* pt_regs->bp */ 356 popl %eax /* pt_regs->ax */ 357 popl %ds /* pt_regs->ds (always ignores __dsh) */ 358 popl %es /* pt_regs->es (always ignores __esh) */ 359 popl %fs /* pt_regs->fs (always ignores __fsh) */ 360 popl %gs /* pt_regs->gs (always ignores __gsh) */ 361 decl %ss:early_recursion_flag 362 addl $4, %esp /* pop pt_regs->orig_ax */ 363 iret 364SYM_CODE_END(early_idt_handler_common) 365 366/* This is the default interrupt "handler" :-) */ 367SYM_FUNC_START(early_ignore_irq) 368 cld 369#ifdef CONFIG_PRINTK 370 pushl %eax 371 pushl %ecx 372 pushl %edx 373 pushl %es 374 pushl %ds 375 movl $(__KERNEL_DS),%eax 376 movl %eax,%ds 377 movl %eax,%es 378 cmpl $2,early_recursion_flag 379 je hlt_loop 380 incl early_recursion_flag 381 pushl 16(%esp) 382 pushl 24(%esp) 383 pushl 32(%esp) 384 pushl 40(%esp) 385 pushl $int_msg 386 call _printk 387 388 call dump_stack 389 390 addl $(5*4),%esp 391 popl %ds 392 popl %es 393 popl %edx 394 popl %ecx 395 popl %eax 396#endif 397 iret 398 399hlt_loop: 400 hlt 401 jmp hlt_loop 402SYM_FUNC_END(early_ignore_irq) 403 404__INITDATA 405 .align 4 406SYM_DATA(early_recursion_flag, .long 0) 407 408__REFDATA 409 .align 4 410SYM_DATA(initial_code, .long i386_start_kernel) 411 412#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION 413#define PGD_ALIGN (2 * PAGE_SIZE) 414#define PTI_USER_PGD_FILL 1024 415#else 416#define PGD_ALIGN (PAGE_SIZE) 417#define PTI_USER_PGD_FILL 0 418#endif 419/* 420 * BSS section 421 */ 422__PAGE_ALIGNED_BSS 423 .align PGD_ALIGN 424#ifdef CONFIG_X86_PAE 425.globl initial_pg_pmd 426initial_pg_pmd: 427 .fill 1024*KPMDS,4,0 428#else 429.globl initial_page_table 430initial_page_table: 431 .fill 1024,4,0 432#endif 433 .align PGD_ALIGN 434initial_pg_fixmap: 435 .fill 1024,4,0 436.globl swapper_pg_dir 437 .align PGD_ALIGN 438swapper_pg_dir: 439 .fill 1024,4,0 440 .fill PTI_USER_PGD_FILL,4,0 441.globl empty_zero_page 442empty_zero_page: 443 .fill 4096,1,0 444EXPORT_SYMBOL(empty_zero_page) 445 446/* 447 * This starts the data section. 448 */ 449#ifdef CONFIG_X86_PAE 450__PAGE_ALIGNED_DATA 451 /* Page-aligned for the benefit of paravirt? */ 452 .align PGD_ALIGN 453SYM_DATA_START(initial_page_table) 454 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */ 455# if KPMDS == 3 456 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 457 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 458 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0 459# elif KPMDS == 2 460 .long 0,0 461 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 462 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 463# elif KPMDS == 1 464 .long 0,0 465 .long 0,0 466 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 467# else 468# error "Kernel PMDs should be 1, 2 or 3" 469# endif 470 .align PAGE_SIZE /* needs to be page-sized too */ 471 472#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION 473 /* 474 * PTI needs another page so sync_initial_pagetable() works correctly 475 * and does not scribble over the data which is placed behind the 476 * actual initial_page_table. See clone_pgd_range(). 477 */ 478 .fill 1024, 4, 0 479#endif 480 481SYM_DATA_END(initial_page_table) 482#endif 483 484.data 485.balign 4 486SYM_DATA(initial_stack, .long __top_init_kernel_stack) 487 488__INITRODATA 489int_msg: 490 .asciz "Unknown interrupt or fault at: %p %p %p\n" 491 492#include "../xen/xen-head.S" 493 494/* 495 * The IDT and GDT 'descriptors' are a strange 48-bit object 496 * only used by the lidt and lgdt instructions. They are not 497 * like usual segment descriptors - they consist of a 16-bit 498 * segment size, and 32-bit linear address value: 499 */ 500 501 .data 502 ALIGN 503# early boot GDT descriptor (must use 1:1 address mapping) 504 .word 0 # 32 bit align gdt_desc.address 505SYM_DATA_START_LOCAL(boot_gdt_descr) 506 .word __BOOT_DS+7 507 .long boot_gdt - __PAGE_OFFSET 508SYM_DATA_END(boot_gdt_descr) 509 510# boot GDT descriptor (later on used by CPU#0): 511 .word 0 # 32 bit align gdt_desc.address 512SYM_DATA_START(early_gdt_descr) 513 .word GDT_ENTRIES*8-1 514 .long gdt_page /* Overwritten for secondary CPUs */ 515SYM_DATA_END(early_gdt_descr) 516 517/* 518 * The boot_gdt must mirror the equivalent in setup.S and is 519 * used only for booting. 520 */ 521 .align L1_CACHE_BYTES 522SYM_DATA_START(boot_gdt) 523 .fill GDT_ENTRY_BOOT_CS,8,0 524 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ 525 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ 526SYM_DATA_END(boot_gdt) 527