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 102 movsl 103 movl pa(boot_params) + NEW_CL_POINTER,%esi 104 andl %esi,%esi 105 jz 1f # No command line 106 movl $pa(boot_command_line),%edi 107 movl $(COMMAND_LINE_SIZE/4),%ecx 108 rep 109 movsl 1101: 111 112#ifdef CONFIG_OLPC 113 /* save OFW's pgdir table for later use when calling into OFW */ 114 movl %cr3, %eax 115 movl %eax, pa(olpc_ofw_pgd) 116#endif 117 118 /* Create early pagetables. */ 119 call mk_early_pgtbl_32 120 121 /* Do early initialization of the fixmap area */ 122 movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax 123#ifdef CONFIG_X86_PAE 124#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ 125 movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) 126#else 127 movl %eax,pa(initial_page_table+0xffc) 128#endif 129 130 jmp .Ldefault_entry 131SYM_CODE_END(startup_32) 132 133/* 134 * Non-boot CPU entry point; entered from trampoline.S 135 * We can't lgdt here, because lgdt itself uses a data segment, but 136 * we know the trampoline has already loaded the boot_gdt for us. 137 * 138 * If cpu hotplug is not supported then this code can go in init section 139 * which will be freed later 140 */ 141SYM_FUNC_START(startup_32_smp) 142 cld 143 movl $(__BOOT_DS),%eax 144 movl %eax,%ds 145 movl %eax,%es 146 movl %eax,%fs 147 movl %eax,%gs 148 movl pa(initial_stack),%ecx 149 movl %eax,%ss 150 leal -__PAGE_OFFSET(%ecx),%esp 151 152.Ldefault_entry: 153 movl $(CR0_STATE & ~X86_CR0_PG),%eax 154 movl %eax,%cr0 155 156/* 157 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave 158 * bits like NT set. This would confuse the debugger if this code is traced. So 159 * initialize them properly now before switching to protected mode. That means 160 * DF in particular (even though we have cleared it earlier after copying the 161 * command line) because GCC expects it. 162 */ 163 pushl $0 164 popfl 165 166/* 167 * New page tables may be in 4Mbyte page mode and may be using the global pages. 168 * 169 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists 170 * if and only if CPUID exists and has flags other than the FPU flag set. 171 */ 172 movl $-1,pa(X86_CPUID) # preset CPUID level 173 movl $X86_EFLAGS_ID,%ecx 174 pushl %ecx 175 popfl # set EFLAGS=ID 176 pushfl 177 popl %eax # get EFLAGS 178 testl $X86_EFLAGS_ID,%eax # did EFLAGS.ID remained set? 179 jz .Lenable_paging # hw disallowed setting of ID bit 180 # which means no CPUID and no CR4 181 182 xorl %eax,%eax 183 cpuid 184 movl %eax,pa(X86_CPUID) # save largest std CPUID function 185 186 movl $1,%eax 187 cpuid 188 andl $~1,%edx # Ignore CPUID.FPU 189 jz .Lenable_paging # No flags or only CPUID.FPU = no CR4 190 191 movl pa(mmu_cr4_features),%eax 192 movl %eax,%cr4 193 194 testb $X86_CR4_PAE, %al # check if PAE is enabled 195 jz .Lenable_paging 196 197 /* Check if extended functions are implemented */ 198 movl $0x80000000, %eax 199 cpuid 200 /* Value must be in the range 0x80000001 to 0x8000ffff */ 201 subl $0x80000001, %eax 202 cmpl $(0x8000ffff-0x80000001), %eax 203 ja .Lenable_paging 204 205 /* Clear bogus XD_DISABLE bits */ 206 call verify_cpu 207 208 mov $0x80000001, %eax 209 cpuid 210 /* Execute Disable bit supported? */ 211 btl $(X86_FEATURE_NX & 31), %edx 212 jnc .Lenable_paging 213 214 /* Setup EFER (Extended Feature Enable Register) */ 215 movl $MSR_EFER, %ecx 216 rdmsr 217 218 btsl $_EFER_NX, %eax 219 /* Make changes effective */ 220 wrmsr 221 222.Lenable_paging: 223 224/* 225 * Enable paging 226 */ 227 movl $pa(initial_page_table), %eax 228 movl %eax,%cr3 /* set the page table pointer.. */ 229 movl $CR0_STATE,%eax 230 movl %eax,%cr0 /* ..and set paging (PG) bit */ 231 ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ 2321: 233 /* Shift the stack pointer to a virtual address */ 234 addl $__PAGE_OFFSET, %esp 235 236/* 237 * Check if it is 486 238 */ 239 movb $4,X86 # at least 486 240 cmpl $-1,X86_CPUID 241 je .Lis486 242 243 /* get vendor info */ 244 xorl %eax,%eax # call CPUID with 0 -> return vendor ID 245 cpuid 246 movl %eax,X86_CPUID # save CPUID level 247 movl %ebx,X86_VENDOR_ID # lo 4 chars 248 movl %edx,X86_VENDOR_ID+4 # next 4 chars 249 movl %ecx,X86_VENDOR_ID+8 # last 4 chars 250 251 orl %eax,%eax # do we have processor info as well? 252 je .Lis486 253 254 movl $1,%eax # Use the CPUID instruction to get CPU type 255 cpuid 256 movb %al,%cl # save reg for future use 257 andb $0x0f,%ah # mask processor family 258 movb %ah,X86 259 andb $0xf0,%al # mask model 260 shrb $4,%al 261 movb %al,X86_MODEL 262 andb $0x0f,%cl # mask mask revision 263 movb %cl,X86_STEPPING 264 movl %edx,X86_CAPABILITY 265 266.Lis486: 267 movl $0x50022,%ecx # set AM, WP, NE and MP 268 movl %cr0,%eax 269 andl $0x80000011,%eax # Save PG,PE,ET 270 orl %ecx,%eax 271 movl %eax,%cr0 272 273 lgdt early_gdt_descr 274 ljmp $(__KERNEL_CS),$1f 2751: movl $(__KERNEL_DS),%eax # reload all the segment registers 276 movl %eax,%ss # after changing gdt. 277 278 movl $(__USER_DS),%eax # DS/ES contains default USER segment 279 movl %eax,%ds 280 movl %eax,%es 281 282 movl $(__KERNEL_PERCPU), %eax 283 movl %eax,%fs # set this cpu's percpu 284 285 xorl %eax,%eax 286 movl %eax,%gs # clear possible garbage in %gs 287 288 xorl %eax,%eax # Clear LDT 289 lldt %ax 290 291 call *(initial_code) 2921: jmp 1b 293SYM_FUNC_END(startup_32_smp) 294 295#include "verify_cpu.S" 296 297__INIT 298SYM_FUNC_START(early_idt_handler_array) 299 # 36(%esp) %eflags 300 # 32(%esp) %cs 301 # 28(%esp) %eip 302 # 24(%rsp) error code 303 i = 0 304 .rept NUM_EXCEPTION_VECTORS 305 .if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0 306 pushl $0 # Dummy error code, to make stack frame uniform 307 .endif 308 pushl $i # 20(%esp) Vector number 309 jmp early_idt_handler_common 310 i = i + 1 311 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 312 .endr 313SYM_FUNC_END(early_idt_handler_array) 314 315SYM_CODE_START_LOCAL(early_idt_handler_common) 316 /* 317 * The stack is the hardware frame, an error code or zero, and the 318 * vector number. 319 */ 320 cld 321 322 incl %ss:early_recursion_flag 323 324 /* The vector number is in pt_regs->gs */ 325 326 cld 327 pushl %fs /* pt_regs->fs (__fsh varies by model) */ 328 pushl %es /* pt_regs->es (__esh varies by model) */ 329 pushl %ds /* pt_regs->ds (__dsh varies by model) */ 330 pushl %eax /* pt_regs->ax */ 331 pushl %ebp /* pt_regs->bp */ 332 pushl %edi /* pt_regs->di */ 333 pushl %esi /* pt_regs->si */ 334 pushl %edx /* pt_regs->dx */ 335 pushl %ecx /* pt_regs->cx */ 336 pushl %ebx /* pt_regs->bx */ 337 338 /* Fix up DS and ES */ 339 movl $(__KERNEL_DS), %ecx 340 movl %ecx, %ds 341 movl %ecx, %es 342 343 /* Load the vector number into EDX */ 344 movl PT_GS(%esp), %edx 345 346 /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ 347 movw %gs, PT_GS(%esp) 348 349 movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ 350 call early_fixup_exception 351 352 popl %ebx /* pt_regs->bx */ 353 popl %ecx /* pt_regs->cx */ 354 popl %edx /* pt_regs->dx */ 355 popl %esi /* pt_regs->si */ 356 popl %edi /* pt_regs->di */ 357 popl %ebp /* pt_regs->bp */ 358 popl %eax /* pt_regs->ax */ 359 popl %ds /* pt_regs->ds (always ignores __dsh) */ 360 popl %es /* pt_regs->es (always ignores __esh) */ 361 popl %fs /* pt_regs->fs (always ignores __fsh) */ 362 popl %gs /* pt_regs->gs (always ignores __gsh) */ 363 decl %ss:early_recursion_flag 364 addl $4, %esp /* pop pt_regs->orig_ax */ 365 iret 366SYM_CODE_END(early_idt_handler_common) 367 368/* This is the default interrupt "handler" :-) */ 369SYM_FUNC_START(early_ignore_irq) 370 cld 371#ifdef CONFIG_PRINTK 372 pushl %eax 373 pushl %ecx 374 pushl %edx 375 pushl %es 376 pushl %ds 377 movl $(__KERNEL_DS),%eax 378 movl %eax,%ds 379 movl %eax,%es 380 cmpl $2,early_recursion_flag 381 je hlt_loop 382 incl early_recursion_flag 383 pushl 16(%esp) 384 pushl 24(%esp) 385 pushl 32(%esp) 386 pushl 40(%esp) 387 pushl $int_msg 388 call _printk 389 390 call dump_stack 391 392 addl $(5*4),%esp 393 popl %ds 394 popl %es 395 popl %edx 396 popl %ecx 397 popl %eax 398#endif 399 iret 400 401hlt_loop: 402 hlt 403 jmp hlt_loop 404SYM_FUNC_END(early_ignore_irq) 405 406__INITDATA 407 .align 4 408SYM_DATA(early_recursion_flag, .long 0) 409 410__REFDATA 411 .align 4 412SYM_DATA(initial_code, .long i386_start_kernel) 413 414#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION 415#define PGD_ALIGN (2 * PAGE_SIZE) 416#define PTI_USER_PGD_FILL 1024 417#else 418#define PGD_ALIGN (PAGE_SIZE) 419#define PTI_USER_PGD_FILL 0 420#endif 421/* 422 * BSS section 423 */ 424__PAGE_ALIGNED_BSS 425 .align PGD_ALIGN 426#ifdef CONFIG_X86_PAE 427.globl initial_pg_pmd 428initial_pg_pmd: 429 .fill 1024*KPMDS,4,0 430#else 431.globl initial_page_table 432initial_page_table: 433 .fill 1024,4,0 434#endif 435 .align PGD_ALIGN 436initial_pg_fixmap: 437 .fill 1024,4,0 438.globl swapper_pg_dir 439 .align PGD_ALIGN 440swapper_pg_dir: 441 .fill 1024,4,0 442 .fill PTI_USER_PGD_FILL,4,0 443.globl empty_zero_page 444empty_zero_page: 445 .fill 4096,1,0 446EXPORT_SYMBOL(empty_zero_page) 447 448/* 449 * This starts the data section. 450 */ 451#ifdef CONFIG_X86_PAE 452__PAGE_ALIGNED_DATA 453 /* Page-aligned for the benefit of paravirt? */ 454 .align PGD_ALIGN 455SYM_DATA_START(initial_page_table) 456 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */ 457# if KPMDS == 3 458 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 459 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 460 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0 461# elif KPMDS == 2 462 .long 0,0 463 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 464 .long pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0 465# elif KPMDS == 1 466 .long 0,0 467 .long 0,0 468 .long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 469# else 470# error "Kernel PMDs should be 1, 2 or 3" 471# endif 472 .align PAGE_SIZE /* needs to be page-sized too */ 473 474#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION 475 /* 476 * PTI needs another page so sync_initial_pagetable() works correctly 477 * and does not scribble over the data which is placed behind the 478 * actual initial_page_table. See clone_pgd_range(). 479 */ 480 .fill 1024, 4, 0 481#endif 482 483SYM_DATA_END(initial_page_table) 484#endif 485 486.data 487.balign 4 488SYM_DATA(initial_stack, .long __top_init_kernel_stack) 489 490__INITRODATA 491int_msg: 492 .asciz "Unknown interrupt or fault at: %p %p %p\n" 493 494#include "../xen/xen-head.S" 495 496/* 497 * The IDT and GDT 'descriptors' are a strange 48-bit object 498 * only used by the lidt and lgdt instructions. They are not 499 * like usual segment descriptors - they consist of a 16-bit 500 * segment size, and 32-bit linear address value: 501 */ 502 503 .data 504 ALIGN 505# early boot GDT descriptor (must use 1:1 address mapping) 506 .word 0 # 32 bit align gdt_desc.address 507SYM_DATA_START_LOCAL(boot_gdt_descr) 508 .word __BOOT_DS+7 509 .long boot_gdt - __PAGE_OFFSET 510SYM_DATA_END(boot_gdt_descr) 511 512# boot GDT descriptor (later on used by CPU#0): 513 .word 0 # 32 bit align gdt_desc.address 514SYM_DATA_START(early_gdt_descr) 515 .word GDT_ENTRIES*8-1 516 .long gdt_page /* Overwritten for secondary CPUs */ 517SYM_DATA_END(early_gdt_descr) 518 519/* 520 * The boot_gdt must mirror the equivalent in setup.S and is 521 * used only for booting. 522 */ 523 .align L1_CACHE_BYTES 524SYM_DATA_START(boot_gdt) 525 .fill GDT_ENTRY_BOOT_CS,8,0 526 .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */ 527 .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */ 528SYM_DATA_END(boot_gdt) 529