1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * linux/boot/head.S 4 * 5 * Copyright (C) 1991, 1992, 1993 Linus Torvalds 6 */ 7 8/* 9 * head.S contains the 32-bit startup code. 10 * 11 * NOTE!!! Startup happens at absolute address 0x00001000, which is also where 12 * the page directory will exist. The startup code will be overwritten by 13 * the page directory. [According to comments etc elsewhere on a compressed 14 * kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC] 15 * 16 * Page 0 is deliberately kept safe, since System Management Mode code in 17 * laptops may need to access the BIOS data stored there. This is also 18 * useful for future device drivers that either access the BIOS via VM86 19 * mode. 20 */ 21 22/* 23 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 24 */ 25 .code32 26 .text 27 28#include <linux/init.h> 29#include <linux/linkage.h> 30#include <asm/segment.h> 31#include <asm/boot.h> 32#include <asm/msr.h> 33#include <asm/processor-flags.h> 34#include <asm/asm-offsets.h> 35#include <asm/bootparam.h> 36#include <asm/desc_defs.h> 37#include <asm/trapnr.h> 38#include "pgtable.h" 39 40/* 41 * Fix alignment at 16 bytes. Following CONFIG_FUNCTION_ALIGNMENT will result 42 * in assembly errors due to trying to move .org backward due to the excessive 43 * alignment. 44 */ 45#undef __ALIGN 46#define __ALIGN .balign 16, 0x90 47 48/* 49 * Locally defined symbols should be marked hidden: 50 */ 51 .hidden _bss 52 .hidden _ebss 53 .hidden _end 54 55 __HEAD 56 57/* 58 * This macro gives the relative virtual address of X, i.e. the offset of X 59 * from startup_32. This is the same as the link-time virtual address of X, 60 * since startup_32 is at 0, but defining it this way tells the 61 * assembler/linker that we do not want the actual run-time address of X. This 62 * prevents the linker from trying to create unwanted run-time relocation 63 * entries for the reference when the compressed kernel is linked as PIE. 64 * 65 * A reference X(%reg) will result in the link-time VA of X being stored with 66 * the instruction, and a run-time R_X86_64_RELATIVE relocation entry that 67 * adds the 64-bit base address where the kernel is loaded. 68 * 69 * Replacing it with (X-startup_32)(%reg) results in the offset being stored, 70 * and no run-time relocation. 71 * 72 * The macro should be used as a displacement with a base register containing 73 * the run-time address of startup_32 [i.e. rva(X)(%reg)], or as an immediate 74 * [$ rva(X)]. 75 * 76 * This macro can only be used from within the .head.text section, since the 77 * expression requires startup_32 to be in the same section as the code being 78 * assembled. 79 */ 80#define rva(X) ((X) - startup_32) 81 82 .code32 83SYM_FUNC_START(startup_32) 84 /* 85 * 32bit entry is 0 and it is ABI so immutable! 86 * If we come here directly from a bootloader, 87 * kernel(text+data+bss+brk) ramdisk, zero_page, command line 88 * all need to be under the 4G limit. 89 */ 90 cld 91 cli 92 93/* 94 * Calculate the delta between where we were compiled to run 95 * at and where we were actually loaded at. This can only be done 96 * with a short local call on x86. Nothing else will tell us what 97 * address we are running at. The reserved chunk of the real-mode 98 * data at 0x1e4 (defined as a scratch field) are used as the stack 99 * for this calculation. Only 4 bytes are needed. 100 */ 101 leal (BP_scratch+4)(%esi), %esp 102 call 1f 1031: popl %ebp 104 subl $ rva(1b), %ebp 105 106 /* Load new GDT with the 64bit segments using 32bit descriptor */ 107 leal rva(gdt)(%ebp), %eax 108 movl %eax, 2(%eax) 109 lgdt (%eax) 110 111 /* Load segment registers with our descriptors */ 112 movl $__BOOT_DS, %eax 113 movl %eax, %ds 114 movl %eax, %es 115 movl %eax, %fs 116 movl %eax, %gs 117 movl %eax, %ss 118 119 /* Setup a stack and load CS from current GDT */ 120 leal rva(boot_stack_end)(%ebp), %esp 121 122 pushl $__KERNEL32_CS 123 leal rva(1f)(%ebp), %eax 124 pushl %eax 125 lretl 1261: 127 128 /* Setup Exception handling for SEV-ES */ 129#ifdef CONFIG_AMD_MEM_ENCRYPT 130 call startup32_load_idt 131#endif 132 133 /* Make sure cpu supports long mode. */ 134 call verify_cpu 135 testl %eax, %eax 136 jnz .Lno_longmode 137 138/* 139 * Compute the delta between where we were compiled to run at 140 * and where the code will actually run at. 141 * 142 * %ebp contains the address we are loaded at by the boot loader and %ebx 143 * contains the address where we should move the kernel image temporarily 144 * for safe in-place decompression. 145 */ 146 147#ifdef CONFIG_RELOCATABLE 148 movl %ebp, %ebx 149 150#ifdef CONFIG_EFI_STUB 151/* 152 * If we were loaded via the EFI LoadImage service, startup_32 will be at an 153 * offset to the start of the space allocated for the image. efi_pe_entry will 154 * set up image_offset to tell us where the image actually starts, so that we 155 * can use the full available buffer. 156 * image_offset = startup_32 - image_base 157 * Otherwise image_offset will be zero and has no effect on the calculations. 158 */ 159 subl rva(image_offset)(%ebp), %ebx 160#endif 161 162 movl BP_kernel_alignment(%esi), %eax 163 decl %eax 164 addl %eax, %ebx 165 notl %eax 166 andl %eax, %ebx 167 cmpl $LOAD_PHYSICAL_ADDR, %ebx 168 jae 1f 169#endif 170 movl $LOAD_PHYSICAL_ADDR, %ebx 1711: 172 173 /* Target address to relocate to for decompression */ 174 addl BP_init_size(%esi), %ebx 175 subl $ rva(_end), %ebx 176 177/* 178 * Prepare for entering 64 bit mode 179 */ 180 181 /* Enable PAE mode */ 182 movl %cr4, %eax 183 orl $X86_CR4_PAE, %eax 184 movl %eax, %cr4 185 186 /* 187 * Build early 4G boot pagetable 188 */ 189 /* 190 * If SEV is active then set the encryption mask in the page tables. 191 * This will ensure that when the kernel is copied and decompressed 192 * it will be done so encrypted. 193 */ 194 xorl %edx, %edx 195#ifdef CONFIG_AMD_MEM_ENCRYPT 196 call get_sev_encryption_bit 197 xorl %edx, %edx 198 testl %eax, %eax 199 jz 1f 200 subl $32, %eax /* Encryption bit is always above bit 31 */ 201 bts %eax, %edx /* Set encryption mask for page tables */ 202 /* 203 * Set MSR_AMD64_SEV_ENABLED_BIT in sev_status so that 204 * startup32_check_sev_cbit() will do a check. sev_enable() will 205 * initialize sev_status with all the bits reported by 206 * MSR_AMD_SEV_STATUS later, but only MSR_AMD64_SEV_ENABLED_BIT 207 * needs to be set for now. 208 */ 209 movl $1, rva(sev_status)(%ebp) 2101: 211#endif 212 213 /* Initialize Page tables to 0 */ 214 leal rva(pgtable)(%ebx), %edi 215 xorl %eax, %eax 216 movl $(BOOT_INIT_PGT_SIZE/4), %ecx 217 rep stosl 218 219 /* Build Level 4 */ 220 leal rva(pgtable + 0)(%ebx), %edi 221 leal 0x1007 (%edi), %eax 222 movl %eax, 0(%edi) 223 addl %edx, 4(%edi) 224 225 /* Build Level 3 */ 226 leal rva(pgtable + 0x1000)(%ebx), %edi 227 leal 0x1007(%edi), %eax 228 movl $4, %ecx 2291: movl %eax, 0x00(%edi) 230 addl %edx, 0x04(%edi) 231 addl $0x00001000, %eax 232 addl $8, %edi 233 decl %ecx 234 jnz 1b 235 236 /* Build Level 2 */ 237 leal rva(pgtable + 0x2000)(%ebx), %edi 238 movl $0x00000183, %eax 239 movl $2048, %ecx 2401: movl %eax, 0(%edi) 241 addl %edx, 4(%edi) 242 addl $0x00200000, %eax 243 addl $8, %edi 244 decl %ecx 245 jnz 1b 246 247 /* Enable the boot page tables */ 248 leal rva(pgtable)(%ebx), %eax 249 movl %eax, %cr3 250 251 /* Enable Long mode in EFER (Extended Feature Enable Register) */ 252 movl $MSR_EFER, %ecx 253 rdmsr 254 btsl $_EFER_LME, %eax 255 wrmsr 256 257 /* After gdt is loaded */ 258 xorl %eax, %eax 259 lldt %ax 260 movl $__BOOT_TSS, %eax 261 ltr %ax 262 263#ifdef CONFIG_AMD_MEM_ENCRYPT 264 /* Check if the C-bit position is correct when SEV is active */ 265 call startup32_check_sev_cbit 266#endif 267 268 /* 269 * Setup for the jump to 64bit mode 270 * 271 * When the jump is performed we will be in long mode but 272 * in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1 273 * (and in turn EFER.LMA = 1). To jump into 64bit mode we use 274 * the new gdt/idt that has __KERNEL_CS with CS.L = 1. 275 * We place all of the values on our mini stack so lret can 276 * used to perform that far jump. 277 */ 278 leal rva(startup_64)(%ebp), %eax 279#ifdef CONFIG_EFI_MIXED 280 cmpb $1, rva(efi_is64)(%ebp) 281 je 1f 282 leal rva(startup_64_mixed_mode)(%ebp), %eax 2831: 284#endif 285 286 pushl $__KERNEL_CS 287 pushl %eax 288 289 /* Enter paged protected Mode, activating Long Mode */ 290 movl $CR0_STATE, %eax 291 movl %eax, %cr0 292 293 /* Jump from 32bit compatibility mode into 64bit mode. */ 294 lret 295SYM_FUNC_END(startup_32) 296 297#if IS_ENABLED(CONFIG_EFI_MIXED) && IS_ENABLED(CONFIG_EFI_HANDOVER_PROTOCOL) 298 .org 0x190 299SYM_FUNC_START(efi32_stub_entry) 300 add $0x4, %esp /* Discard return address */ 301 popl %ecx 302 popl %edx 303 popl %esi 304 jmp efi32_entry 305SYM_FUNC_END(efi32_stub_entry) 306#endif 307 308 .code64 309 .org 0x200 310SYM_CODE_START(startup_64) 311 /* 312 * 64bit entry is 0x200 and it is ABI so immutable! 313 * We come here either from startup_32 or directly from a 314 * 64bit bootloader. 315 * If we come here from a bootloader, kernel(text+data+bss+brk), 316 * ramdisk, zero_page, command line could be above 4G. 317 * We depend on an identity mapped page table being provided 318 * that maps our entire kernel(text+data+bss+brk), zero page 319 * and command line. 320 */ 321 322 cld 323 cli 324 325 /* Setup data segments. */ 326 xorl %eax, %eax 327 movl %eax, %ds 328 movl %eax, %es 329 movl %eax, %ss 330 movl %eax, %fs 331 movl %eax, %gs 332 333 /* 334 * Compute the decompressed kernel start address. It is where 335 * we were loaded at aligned to a 2M boundary. %rbp contains the 336 * decompressed kernel start address. 337 * 338 * If it is a relocatable kernel then decompress and run the kernel 339 * from load address aligned to 2MB addr, otherwise decompress and 340 * run the kernel from LOAD_PHYSICAL_ADDR 341 * 342 * We cannot rely on the calculation done in 32-bit mode, since we 343 * may have been invoked via the 64-bit entry point. 344 */ 345 346 /* Start with the delta to where the kernel will run at. */ 347#ifdef CONFIG_RELOCATABLE 348 leaq startup_32(%rip) /* - $startup_32 */, %rbp 349 350#ifdef CONFIG_EFI_STUB 351/* 352 * If we were loaded via the EFI LoadImage service, startup_32 will be at an 353 * offset to the start of the space allocated for the image. efi_pe_entry will 354 * set up image_offset to tell us where the image actually starts, so that we 355 * can use the full available buffer. 356 * image_offset = startup_32 - image_base 357 * Otherwise image_offset will be zero and has no effect on the calculations. 358 */ 359 movl image_offset(%rip), %eax 360 subq %rax, %rbp 361#endif 362 363 movl BP_kernel_alignment(%rsi), %eax 364 decl %eax 365 addq %rax, %rbp 366 notq %rax 367 andq %rax, %rbp 368 cmpq $LOAD_PHYSICAL_ADDR, %rbp 369 jae 1f 370#endif 371 movq $LOAD_PHYSICAL_ADDR, %rbp 3721: 373 374 /* Target address to relocate to for decompression */ 375 movl BP_init_size(%rsi), %ebx 376 subl $ rva(_end), %ebx 377 addq %rbp, %rbx 378 379 /* Set up the stack */ 380 leaq rva(boot_stack_end)(%rbx), %rsp 381 382 /* 383 * At this point we are in long mode with 4-level paging enabled, 384 * but we might want to enable 5-level paging or vice versa. 385 * 386 * The problem is that we cannot do it directly. Setting or clearing 387 * CR4.LA57 in long mode would trigger #GP. So we need to switch off 388 * long mode and paging first. 389 * 390 * We also need a trampoline in lower memory to switch over from 391 * 4- to 5-level paging for cases when the bootloader puts the kernel 392 * above 4G, but didn't enable 5-level paging for us. 393 * 394 * The same trampoline can be used to switch from 5- to 4-level paging 395 * mode, like when starting 4-level paging kernel via kexec() when 396 * original kernel worked in 5-level paging mode. 397 * 398 * For the trampoline, we need the top page table to reside in lower 399 * memory as we don't have a way to load 64-bit values into CR3 in 400 * 32-bit mode. 401 * 402 * We go though the trampoline even if we don't have to: if we're 403 * already in a desired paging mode. This way the trampoline code gets 404 * tested on every boot. 405 */ 406 407 /* Make sure we have GDT with 32-bit code segment */ 408 leaq gdt64(%rip), %rax 409 addq %rax, 2(%rax) 410 lgdt (%rax) 411 412 /* Reload CS so IRET returns to a CS actually in the GDT */ 413 pushq $__KERNEL_CS 414 leaq .Lon_kernel_cs(%rip), %rax 415 pushq %rax 416 lretq 417 418.Lon_kernel_cs: 419 420 pushq %rsi 421 call load_stage1_idt 422 popq %rsi 423 424#ifdef CONFIG_AMD_MEM_ENCRYPT 425 /* 426 * Now that the stage1 interrupt handlers are set up, #VC exceptions from 427 * CPUID instructions can be properly handled for SEV-ES guests. 428 * 429 * For SEV-SNP, the CPUID table also needs to be set up in advance of any 430 * CPUID instructions being issued, so go ahead and do that now via 431 * sev_enable(), which will also handle the rest of the SEV-related 432 * detection/setup to ensure that has been done in advance of any dependent 433 * code. 434 */ 435 pushq %rsi 436 movq %rsi, %rdi /* real mode address */ 437 call sev_enable 438 popq %rsi 439#endif 440 441 /* 442 * paging_prepare() sets up the trampoline and checks if we need to 443 * enable 5-level paging. 444 * 445 * paging_prepare() returns a two-quadword structure which lands 446 * into RDX:RAX: 447 * - Address of the trampoline is returned in RAX. 448 * - Non zero RDX means trampoline needs to enable 5-level 449 * paging. 450 * 451 * RSI holds real mode data and needs to be preserved across 452 * this function call. 453 */ 454 pushq %rsi 455 movq %rsi, %rdi /* real mode address */ 456 call paging_prepare 457 popq %rsi 458 459 /* Save the trampoline address in RCX */ 460 movq %rax, %rcx 461 462 /* 463 * Load the address of trampoline_return() into RDI. 464 * It will be used by the trampoline to return to the main code. 465 */ 466 leaq trampoline_return(%rip), %rdi 467 468 /* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */ 469 pushq $__KERNEL32_CS 470 leaq TRAMPOLINE_32BIT_CODE_OFFSET(%rax), %rax 471 pushq %rax 472 lretq 473trampoline_return: 474 /* Restore the stack, the 32-bit trampoline uses its own stack */ 475 leaq rva(boot_stack_end)(%rbx), %rsp 476 477 /* 478 * cleanup_trampoline() would restore trampoline memory. 479 * 480 * RDI is address of the page table to use instead of page table 481 * in trampoline memory (if required). 482 * 483 * RSI holds real mode data and needs to be preserved across 484 * this function call. 485 */ 486 pushq %rsi 487 leaq rva(top_pgtable)(%rbx), %rdi 488 call cleanup_trampoline 489 popq %rsi 490 491 /* Zero EFLAGS */ 492 pushq $0 493 popfq 494 495/* 496 * Copy the compressed kernel to the end of our buffer 497 * where decompression in place becomes safe. 498 */ 499 pushq %rsi 500 leaq (_bss-8)(%rip), %rsi 501 leaq rva(_bss-8)(%rbx), %rdi 502 movl $(_bss - startup_32), %ecx 503 shrl $3, %ecx 504 std 505 rep movsq 506 cld 507 popq %rsi 508 509 /* 510 * The GDT may get overwritten either during the copy we just did or 511 * during extract_kernel below. To avoid any issues, repoint the GDTR 512 * to the new copy of the GDT. 513 */ 514 leaq rva(gdt64)(%rbx), %rax 515 leaq rva(gdt)(%rbx), %rdx 516 movq %rdx, 2(%rax) 517 lgdt (%rax) 518 519/* 520 * Jump to the relocated address. 521 */ 522 leaq rva(.Lrelocated)(%rbx), %rax 523 jmp *%rax 524SYM_CODE_END(startup_64) 525 526#ifdef CONFIG_EFI_STUB 527#ifdef CONFIG_EFI_HANDOVER_PROTOCOL 528 .org 0x390 529#endif 530SYM_FUNC_START(efi64_stub_entry) 531 and $~0xf, %rsp /* realign the stack */ 532 movq %rdx, %rbx /* save boot_params pointer */ 533 call efi_main 534 movq %rbx,%rsi 535 leaq rva(startup_64)(%rax), %rax 536 jmp *%rax 537SYM_FUNC_END(efi64_stub_entry) 538SYM_FUNC_ALIAS(efi_stub_entry, efi64_stub_entry) 539#endif 540 541 .text 542SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) 543 544/* 545 * Clear BSS (stack is currently empty) 546 */ 547 xorl %eax, %eax 548 leaq _bss(%rip), %rdi 549 leaq _ebss(%rip), %rcx 550 subq %rdi, %rcx 551 shrq $3, %rcx 552 rep stosq 553 554 pushq %rsi 555 call load_stage2_idt 556 557 /* Pass boot_params to initialize_identity_maps() */ 558 movq (%rsp), %rdi 559 call initialize_identity_maps 560 popq %rsi 561 562/* 563 * Do the extraction, and jump to the new kernel.. 564 */ 565 pushq %rsi /* Save the real mode argument */ 566 movq %rsi, %rdi /* real mode address */ 567 leaq boot_heap(%rip), %rsi /* malloc area for uncompression */ 568 leaq input_data(%rip), %rdx /* input_data */ 569 movl input_len(%rip), %ecx /* input_len */ 570 movq %rbp, %r8 /* output target address */ 571 movl output_len(%rip), %r9d /* decompressed length, end of relocs */ 572 call extract_kernel /* returns kernel entry point in %rax */ 573 popq %rsi 574 575/* 576 * Jump to the decompressed kernel. 577 */ 578 jmp *%rax 579SYM_FUNC_END(.Lrelocated) 580 581 .code32 582/* 583 * This is the 32-bit trampoline that will be copied over to low memory. 584 * 585 * RDI contains the return address (might be above 4G). 586 * ECX contains the base address of the trampoline memory. 587 * Non zero RDX means trampoline needs to enable 5-level paging. 588 */ 589SYM_CODE_START(trampoline_32bit_src) 590 /* Set up data and stack segments */ 591 movl $__KERNEL_DS, %eax 592 movl %eax, %ds 593 movl %eax, %ss 594 595 /* Set up new stack */ 596 leal TRAMPOLINE_32BIT_STACK_END(%ecx), %esp 597 598 /* Disable paging */ 599 movl %cr0, %eax 600 btrl $X86_CR0_PG_BIT, %eax 601 movl %eax, %cr0 602 603 /* Check what paging mode we want to be in after the trampoline */ 604 testl %edx, %edx 605 jz 1f 606 607 /* We want 5-level paging: don't touch CR3 if it already points to 5-level page tables */ 608 movl %cr4, %eax 609 testl $X86_CR4_LA57, %eax 610 jnz 3f 611 jmp 2f 6121: 613 /* We want 4-level paging: don't touch CR3 if it already points to 4-level page tables */ 614 movl %cr4, %eax 615 testl $X86_CR4_LA57, %eax 616 jz 3f 6172: 618 /* Point CR3 to the trampoline's new top level page table */ 619 leal TRAMPOLINE_32BIT_PGTABLE_OFFSET(%ecx), %eax 620 movl %eax, %cr3 6213: 622 /* Set EFER.LME=1 as a precaution in case hypervsior pulls the rug */ 623 pushl %ecx 624 pushl %edx 625 movl $MSR_EFER, %ecx 626 rdmsr 627 btsl $_EFER_LME, %eax 628 /* Avoid writing EFER if no change was made (for TDX guest) */ 629 jc 1f 630 wrmsr 6311: popl %edx 632 popl %ecx 633 634#ifdef CONFIG_X86_MCE 635 /* 636 * Preserve CR4.MCE if the kernel will enable #MC support. 637 * Clearing MCE may fault in some environments (that also force #MC 638 * support). Any machine check that occurs before #MC support is fully 639 * configured will crash the system regardless of the CR4.MCE value set 640 * here. 641 */ 642 movl %cr4, %eax 643 andl $X86_CR4_MCE, %eax 644#else 645 movl $0, %eax 646#endif 647 648 /* Enable PAE and LA57 (if required) paging modes */ 649 orl $X86_CR4_PAE, %eax 650 testl %edx, %edx 651 jz 1f 652 orl $X86_CR4_LA57, %eax 6531: 654 movl %eax, %cr4 655 656 /* Calculate address of paging_enabled() once we are executing in the trampoline */ 657 leal .Lpaging_enabled - trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_OFFSET(%ecx), %eax 658 659 /* Prepare the stack for far return to Long Mode */ 660 pushl $__KERNEL_CS 661 pushl %eax 662 663 /* Enable paging again. */ 664 movl %cr0, %eax 665 btsl $X86_CR0_PG_BIT, %eax 666 movl %eax, %cr0 667 668 lret 669SYM_CODE_END(trampoline_32bit_src) 670 671 .code64 672SYM_FUNC_START_LOCAL_NOALIGN(.Lpaging_enabled) 673 /* Return from the trampoline */ 674 jmp *%rdi 675SYM_FUNC_END(.Lpaging_enabled) 676 677 /* 678 * The trampoline code has a size limit. 679 * Make sure we fail to compile if the trampoline code grows 680 * beyond TRAMPOLINE_32BIT_CODE_SIZE bytes. 681 */ 682 .org trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_SIZE 683 684 .code32 685SYM_FUNC_START_LOCAL_NOALIGN(.Lno_longmode) 686 /* This isn't an x86-64 CPU, so hang intentionally, we cannot continue */ 6871: 688 hlt 689 jmp 1b 690SYM_FUNC_END(.Lno_longmode) 691 692 .globl verify_cpu 693#include "../../kernel/verify_cpu.S" 694 695 .data 696SYM_DATA_START_LOCAL(gdt64) 697 .word gdt_end - gdt - 1 698 .quad gdt - gdt64 699SYM_DATA_END(gdt64) 700 .balign 8 701SYM_DATA_START_LOCAL(gdt) 702 .word gdt_end - gdt - 1 703 .long 0 704 .word 0 705 .quad 0x00cf9a000000ffff /* __KERNEL32_CS */ 706 .quad 0x00af9a000000ffff /* __KERNEL_CS */ 707 .quad 0x00cf92000000ffff /* __KERNEL_DS */ 708 .quad 0x0080890000000000 /* TS descriptor */ 709 .quad 0x0000000000000000 /* TS continued */ 710SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end) 711 712SYM_DATA_START(boot_idt_desc) 713 .word boot_idt_end - boot_idt - 1 714 .quad 0 715SYM_DATA_END(boot_idt_desc) 716 .balign 8 717SYM_DATA_START(boot_idt) 718 .rept BOOT_IDT_ENTRIES 719 .quad 0 720 .quad 0 721 .endr 722SYM_DATA_END_LABEL(boot_idt, SYM_L_GLOBAL, boot_idt_end) 723 724/* 725 * Stack and heap for uncompression 726 */ 727 .bss 728 .balign 4 729SYM_DATA_LOCAL(boot_heap, .fill BOOT_HEAP_SIZE, 1, 0) 730 731SYM_DATA_START_LOCAL(boot_stack) 732 .fill BOOT_STACK_SIZE, 1, 0 733 .balign 16 734SYM_DATA_END_LABEL(boot_stack, SYM_L_LOCAL, boot_stack_end) 735 736/* 737 * Space for page tables (not in .bss so not zeroed) 738 */ 739 .section ".pgtable","aw",@nobits 740 .balign 4096 741SYM_DATA_LOCAL(pgtable, .fill BOOT_PGT_SIZE, 1, 0) 742 743/* 744 * The page table is going to be used instead of page table in the trampoline 745 * memory. 746 */ 747SYM_DATA_LOCAL(top_pgtable, .fill PAGE_SIZE, 1, 0) 748