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 "pgtable.h" 37 38/* 39 * Locally defined symbols should be marked hidden: 40 */ 41 .hidden _bss 42 .hidden _ebss 43 .hidden _got 44 .hidden _egot 45 .hidden _end 46 47 __HEAD 48 .code32 49SYM_FUNC_START(startup_32) 50 /* 51 * 32bit entry is 0 and it is ABI so immutable! 52 * If we come here directly from a bootloader, 53 * kernel(text+data+bss+brk) ramdisk, zero_page, command line 54 * all need to be under the 4G limit. 55 */ 56 cld 57 cli 58 59/* 60 * Calculate the delta between where we were compiled to run 61 * at and where we were actually loaded at. This can only be done 62 * with a short local call on x86. Nothing else will tell us what 63 * address we are running at. The reserved chunk of the real-mode 64 * data at 0x1e4 (defined as a scratch field) are used as the stack 65 * for this calculation. Only 4 bytes are needed. 66 */ 67 leal (BP_scratch+4)(%esi), %esp 68 call 1f 691: popl %ebp 70 subl $1b, %ebp 71 72 /* Load new GDT with the 64bit segments using 32bit descriptor */ 73 leal gdt(%ebp), %eax 74 movl %eax, 2(%eax) 75 lgdt (%eax) 76 77 /* Load segment registers with our descriptors */ 78 movl $__BOOT_DS, %eax 79 movl %eax, %ds 80 movl %eax, %es 81 movl %eax, %fs 82 movl %eax, %gs 83 movl %eax, %ss 84 85/* setup a stack and make sure cpu supports long mode. */ 86 leal boot_stack_end(%ebp), %esp 87 88 call verify_cpu 89 testl %eax, %eax 90 jnz .Lno_longmode 91 92/* 93 * Compute the delta between where we were compiled to run at 94 * and where the code will actually run at. 95 * 96 * %ebp contains the address we are loaded at by the boot loader and %ebx 97 * contains the address where we should move the kernel image temporarily 98 * for safe in-place decompression. 99 */ 100 101#ifdef CONFIG_RELOCATABLE 102 movl %ebp, %ebx 103 104#ifdef CONFIG_EFI_STUB 105/* 106 * If we were loaded via the EFI LoadImage service, startup_32 will be at an 107 * offset to the start of the space allocated for the image. efi_pe_entry will 108 * set up image_offset to tell us where the image actually starts, so that we 109 * can use the full available buffer. 110 * image_offset = startup_32 - image_base 111 * Otherwise image_offset will be zero and has no effect on the calculations. 112 */ 113 subl image_offset(%ebp), %ebx 114#endif 115 116 movl BP_kernel_alignment(%esi), %eax 117 decl %eax 118 addl %eax, %ebx 119 notl %eax 120 andl %eax, %ebx 121 cmpl $LOAD_PHYSICAL_ADDR, %ebx 122 jae 1f 123#endif 124 movl $LOAD_PHYSICAL_ADDR, %ebx 1251: 126 127 /* Target address to relocate to for decompression */ 128 addl BP_init_size(%esi), %ebx 129 subl $_end, %ebx 130 131/* 132 * Prepare for entering 64 bit mode 133 */ 134 135 /* Enable PAE mode */ 136 movl %cr4, %eax 137 orl $X86_CR4_PAE, %eax 138 movl %eax, %cr4 139 140 /* 141 * Build early 4G boot pagetable 142 */ 143 /* 144 * If SEV is active then set the encryption mask in the page tables. 145 * This will insure that when the kernel is copied and decompressed 146 * it will be done so encrypted. 147 */ 148 call get_sev_encryption_bit 149 xorl %edx, %edx 150 testl %eax, %eax 151 jz 1f 152 subl $32, %eax /* Encryption bit is always above bit 31 */ 153 bts %eax, %edx /* Set encryption mask for page tables */ 1541: 155 156 /* Initialize Page tables to 0 */ 157 leal pgtable(%ebx), %edi 158 xorl %eax, %eax 159 movl $(BOOT_INIT_PGT_SIZE/4), %ecx 160 rep stosl 161 162 /* Build Level 4 */ 163 leal pgtable + 0(%ebx), %edi 164 leal 0x1007 (%edi), %eax 165 movl %eax, 0(%edi) 166 addl %edx, 4(%edi) 167 168 /* Build Level 3 */ 169 leal pgtable + 0x1000(%ebx), %edi 170 leal 0x1007(%edi), %eax 171 movl $4, %ecx 1721: movl %eax, 0x00(%edi) 173 addl %edx, 0x04(%edi) 174 addl $0x00001000, %eax 175 addl $8, %edi 176 decl %ecx 177 jnz 1b 178 179 /* Build Level 2 */ 180 leal pgtable + 0x2000(%ebx), %edi 181 movl $0x00000183, %eax 182 movl $2048, %ecx 1831: movl %eax, 0(%edi) 184 addl %edx, 4(%edi) 185 addl $0x00200000, %eax 186 addl $8, %edi 187 decl %ecx 188 jnz 1b 189 190 /* Enable the boot page tables */ 191 leal pgtable(%ebx), %eax 192 movl %eax, %cr3 193 194 /* Enable Long mode in EFER (Extended Feature Enable Register) */ 195 movl $MSR_EFER, %ecx 196 rdmsr 197 btsl $_EFER_LME, %eax 198 wrmsr 199 200 /* After gdt is loaded */ 201 xorl %eax, %eax 202 lldt %ax 203 movl $__BOOT_TSS, %eax 204 ltr %ax 205 206 /* 207 * Setup for the jump to 64bit mode 208 * 209 * When the jump is performend we will be in long mode but 210 * in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1 211 * (and in turn EFER.LMA = 1). To jump into 64bit mode we use 212 * the new gdt/idt that has __KERNEL_CS with CS.L = 1. 213 * We place all of the values on our mini stack so lret can 214 * used to perform that far jump. 215 */ 216 pushl $__KERNEL_CS 217 leal startup_64(%ebp), %eax 218#ifdef CONFIG_EFI_MIXED 219 movl efi32_boot_args(%ebp), %edi 220 cmp $0, %edi 221 jz 1f 222 leal efi64_stub_entry(%ebp), %eax 223 movl efi32_boot_args+4(%ebp), %esi 224 movl efi32_boot_args+8(%ebp), %edx // saved bootparams pointer 225 cmpl $0, %edx 226 jnz 1f 227 leal efi_pe_entry(%ebp), %eax 228 movl %edi, %ecx // MS calling convention 229 movl %esi, %edx 2301: 231#endif 232 pushl %eax 233 234 /* Enter paged protected Mode, activating Long Mode */ 235 movl $(X86_CR0_PG | X86_CR0_PE), %eax /* Enable Paging and Protected mode */ 236 movl %eax, %cr0 237 238 /* Jump from 32bit compatibility mode into 64bit mode. */ 239 lret 240SYM_FUNC_END(startup_32) 241 242#ifdef CONFIG_EFI_MIXED 243 .org 0x190 244SYM_FUNC_START(efi32_stub_entry) 245 add $0x4, %esp /* Discard return address */ 246 popl %ecx 247 popl %edx 248 popl %esi 249 250 call 1f 2511: pop %ebp 252 subl $1b, %ebp 253 254 movl %esi, efi32_boot_args+8(%ebp) 255SYM_INNER_LABEL(efi32_pe_stub_entry, SYM_L_LOCAL) 256 movl %ecx, efi32_boot_args(%ebp) 257 movl %edx, efi32_boot_args+4(%ebp) 258 movb $0, efi_is64(%ebp) 259 260 /* Save firmware GDTR and code/data selectors */ 261 sgdtl efi32_boot_gdt(%ebp) 262 movw %cs, efi32_boot_cs(%ebp) 263 movw %ds, efi32_boot_ds(%ebp) 264 265 /* Disable paging */ 266 movl %cr0, %eax 267 btrl $X86_CR0_PG_BIT, %eax 268 movl %eax, %cr0 269 270 jmp startup_32 271SYM_FUNC_END(efi32_stub_entry) 272#endif 273 274 .code64 275 .org 0x200 276SYM_CODE_START(startup_64) 277 /* 278 * 64bit entry is 0x200 and it is ABI so immutable! 279 * We come here either from startup_32 or directly from a 280 * 64bit bootloader. 281 * If we come here from a bootloader, kernel(text+data+bss+brk), 282 * ramdisk, zero_page, command line could be above 4G. 283 * We depend on an identity mapped page table being provided 284 * that maps our entire kernel(text+data+bss+brk), zero page 285 * and command line. 286 */ 287 288 cld 289 cli 290 291 /* Setup data segments. */ 292 xorl %eax, %eax 293 movl %eax, %ds 294 movl %eax, %es 295 movl %eax, %ss 296 movl %eax, %fs 297 movl %eax, %gs 298 299 /* 300 * Compute the decompressed kernel start address. It is where 301 * we were loaded at aligned to a 2M boundary. %rbp contains the 302 * decompressed kernel start address. 303 * 304 * If it is a relocatable kernel then decompress and run the kernel 305 * from load address aligned to 2MB addr, otherwise decompress and 306 * run the kernel from LOAD_PHYSICAL_ADDR 307 * 308 * We cannot rely on the calculation done in 32-bit mode, since we 309 * may have been invoked via the 64-bit entry point. 310 */ 311 312 /* Start with the delta to where the kernel will run at. */ 313#ifdef CONFIG_RELOCATABLE 314 leaq startup_32(%rip) /* - $startup_32 */, %rbp 315 316#ifdef CONFIG_EFI_STUB 317/* 318 * If we were loaded via the EFI LoadImage service, startup_32 will be at an 319 * offset to the start of the space allocated for the image. efi_pe_entry will 320 * set up image_offset to tell us where the image actually starts, so that we 321 * can use the full available buffer. 322 * image_offset = startup_32 - image_base 323 * Otherwise image_offset will be zero and has no effect on the calculations. 324 */ 325 movl image_offset(%rip), %eax 326 subq %rax, %rbp 327#endif 328 329 movl BP_kernel_alignment(%rsi), %eax 330 decl %eax 331 addq %rax, %rbp 332 notq %rax 333 andq %rax, %rbp 334 cmpq $LOAD_PHYSICAL_ADDR, %rbp 335 jae 1f 336#endif 337 movq $LOAD_PHYSICAL_ADDR, %rbp 3381: 339 340 /* Target address to relocate to for decompression */ 341 movl BP_init_size(%rsi), %ebx 342 subl $_end, %ebx 343 addq %rbp, %rbx 344 345 /* Set up the stack */ 346 leaq boot_stack_end(%rbx), %rsp 347 348 /* 349 * paging_prepare() and cleanup_trampoline() below can have GOT 350 * references. Adjust the table with address we are running at. 351 * 352 * Zero RAX for adjust_got: the GOT was not adjusted before; 353 * there's no adjustment to undo. 354 */ 355 xorq %rax, %rax 356 357 /* 358 * Calculate the address the binary is loaded at and use it as 359 * a GOT adjustment. 360 */ 361 call 1f 3621: popq %rdi 363 subq $1b, %rdi 364 365 call .Ladjust_got 366 367 /* 368 * At this point we are in long mode with 4-level paging enabled, 369 * but we might want to enable 5-level paging or vice versa. 370 * 371 * The problem is that we cannot do it directly. Setting or clearing 372 * CR4.LA57 in long mode would trigger #GP. So we need to switch off 373 * long mode and paging first. 374 * 375 * We also need a trampoline in lower memory to switch over from 376 * 4- to 5-level paging for cases when the bootloader puts the kernel 377 * above 4G, but didn't enable 5-level paging for us. 378 * 379 * The same trampoline can be used to switch from 5- to 4-level paging 380 * mode, like when starting 4-level paging kernel via kexec() when 381 * original kernel worked in 5-level paging mode. 382 * 383 * For the trampoline, we need the top page table to reside in lower 384 * memory as we don't have a way to load 64-bit values into CR3 in 385 * 32-bit mode. 386 * 387 * We go though the trampoline even if we don't have to: if we're 388 * already in a desired paging mode. This way the trampoline code gets 389 * tested on every boot. 390 */ 391 392 /* Make sure we have GDT with 32-bit code segment */ 393 leaq gdt64(%rip), %rax 394 addq %rax, 2(%rax) 395 lgdt (%rax) 396 397 /* Reload CS so IRET returns to a CS actually in the GDT */ 398 pushq $__KERNEL_CS 399 leaq .Lon_kernel_cs(%rip), %rax 400 pushq %rax 401 lretq 402 403.Lon_kernel_cs: 404 405 /* 406 * paging_prepare() sets up the trampoline and checks if we need to 407 * enable 5-level paging. 408 * 409 * paging_prepare() returns a two-quadword structure which lands 410 * into RDX:RAX: 411 * - Address of the trampoline is returned in RAX. 412 * - Non zero RDX means trampoline needs to enable 5-level 413 * paging. 414 * 415 * RSI holds real mode data and needs to be preserved across 416 * this function call. 417 */ 418 pushq %rsi 419 movq %rsi, %rdi /* real mode address */ 420 call paging_prepare 421 popq %rsi 422 423 /* Save the trampoline address in RCX */ 424 movq %rax, %rcx 425 426 /* 427 * Load the address of trampoline_return() into RDI. 428 * It will be used by the trampoline to return to the main code. 429 */ 430 leaq trampoline_return(%rip), %rdi 431 432 /* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */ 433 pushq $__KERNEL32_CS 434 leaq TRAMPOLINE_32BIT_CODE_OFFSET(%rax), %rax 435 pushq %rax 436 lretq 437trampoline_return: 438 /* Restore the stack, the 32-bit trampoline uses its own stack */ 439 leaq boot_stack_end(%rbx), %rsp 440 441 /* 442 * cleanup_trampoline() would restore trampoline memory. 443 * 444 * RDI is address of the page table to use instead of page table 445 * in trampoline memory (if required). 446 * 447 * RSI holds real mode data and needs to be preserved across 448 * this function call. 449 */ 450 pushq %rsi 451 leaq top_pgtable(%rbx), %rdi 452 call cleanup_trampoline 453 popq %rsi 454 455 /* Zero EFLAGS */ 456 pushq $0 457 popfq 458 459 /* 460 * Previously we've adjusted the GOT with address the binary was 461 * loaded at. Now we need to re-adjust for relocation address. 462 * 463 * Calculate the address the binary is loaded at, so that we can 464 * undo the previous GOT adjustment. 465 */ 466 call 1f 4671: popq %rax 468 subq $1b, %rax 469 470 /* The new adjustment is the relocation address */ 471 movq %rbx, %rdi 472 call .Ladjust_got 473 474/* 475 * Copy the compressed kernel to the end of our buffer 476 * where decompression in place becomes safe. 477 */ 478 pushq %rsi 479 leaq (_bss-8)(%rip), %rsi 480 leaq (_bss-8)(%rbx), %rdi 481 movq $_bss /* - $startup_32 */, %rcx 482 shrq $3, %rcx 483 std 484 rep movsq 485 cld 486 popq %rsi 487 488 /* 489 * The GDT may get overwritten either during the copy we just did or 490 * during extract_kernel below. To avoid any issues, repoint the GDTR 491 * to the new copy of the GDT. 492 */ 493 leaq gdt64(%rbx), %rax 494 leaq gdt(%rbx), %rdx 495 movq %rdx, 2(%rax) 496 lgdt (%rax) 497 498/* 499 * Jump to the relocated address. 500 */ 501 leaq .Lrelocated(%rbx), %rax 502 jmp *%rax 503SYM_CODE_END(startup_64) 504 505#ifdef CONFIG_EFI_STUB 506 .org 0x390 507SYM_FUNC_START(efi64_stub_entry) 508SYM_FUNC_START_ALIAS(efi_stub_entry) 509 and $~0xf, %rsp /* realign the stack */ 510 movq %rdx, %rbx /* save boot_params pointer */ 511 call efi_main 512 movq %rbx,%rsi 513 leaq startup_64(%rax), %rax 514 jmp *%rax 515SYM_FUNC_END(efi64_stub_entry) 516SYM_FUNC_END_ALIAS(efi_stub_entry) 517#endif 518 519 .text 520SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) 521 522/* 523 * Clear BSS (stack is currently empty) 524 */ 525 xorl %eax, %eax 526 leaq _bss(%rip), %rdi 527 leaq _ebss(%rip), %rcx 528 subq %rdi, %rcx 529 shrq $3, %rcx 530 rep stosq 531 532/* 533 * Do the extraction, and jump to the new kernel.. 534 */ 535 pushq %rsi /* Save the real mode argument */ 536 movq %rsi, %rdi /* real mode address */ 537 leaq boot_heap(%rip), %rsi /* malloc area for uncompression */ 538 leaq input_data(%rip), %rdx /* input_data */ 539 movl $z_input_len, %ecx /* input_len */ 540 movq %rbp, %r8 /* output target address */ 541 movl $z_output_len, %r9d /* decompressed length, end of relocs */ 542 call extract_kernel /* returns kernel location in %rax */ 543 popq %rsi 544 545/* 546 * Jump to the decompressed kernel. 547 */ 548 jmp *%rax 549SYM_FUNC_END(.Lrelocated) 550 551/* 552 * Adjust the global offset table 553 * 554 * RAX is the previous adjustment of the table to undo (use 0 if it's the 555 * first time we touch GOT). 556 * RDI is the new adjustment to apply. 557 */ 558.Ladjust_got: 559 /* Walk through the GOT adding the address to the entries */ 560 leaq _got(%rip), %rdx 561 leaq _egot(%rip), %rcx 5621: 563 cmpq %rcx, %rdx 564 jae 2f 565 subq %rax, (%rdx) /* Undo previous adjustment */ 566 addq %rdi, (%rdx) /* Apply the new adjustment */ 567 addq $8, %rdx 568 jmp 1b 5692: 570 ret 571 572 .code32 573/* 574 * This is the 32-bit trampoline that will be copied over to low memory. 575 * 576 * RDI contains the return address (might be above 4G). 577 * ECX contains the base address of the trampoline memory. 578 * Non zero RDX means trampoline needs to enable 5-level paging. 579 */ 580SYM_CODE_START(trampoline_32bit_src) 581 /* Set up data and stack segments */ 582 movl $__KERNEL_DS, %eax 583 movl %eax, %ds 584 movl %eax, %ss 585 586 /* Set up new stack */ 587 leal TRAMPOLINE_32BIT_STACK_END(%ecx), %esp 588 589 /* Disable paging */ 590 movl %cr0, %eax 591 btrl $X86_CR0_PG_BIT, %eax 592 movl %eax, %cr0 593 594 /* Check what paging mode we want to be in after the trampoline */ 595 cmpl $0, %edx 596 jz 1f 597 598 /* We want 5-level paging: don't touch CR3 if it already points to 5-level page tables */ 599 movl %cr4, %eax 600 testl $X86_CR4_LA57, %eax 601 jnz 3f 602 jmp 2f 6031: 604 /* We want 4-level paging: don't touch CR3 if it already points to 4-level page tables */ 605 movl %cr4, %eax 606 testl $X86_CR4_LA57, %eax 607 jz 3f 6082: 609 /* Point CR3 to the trampoline's new top level page table */ 610 leal TRAMPOLINE_32BIT_PGTABLE_OFFSET(%ecx), %eax 611 movl %eax, %cr3 6123: 613 /* Set EFER.LME=1 as a precaution in case hypervsior pulls the rug */ 614 pushl %ecx 615 pushl %edx 616 movl $MSR_EFER, %ecx 617 rdmsr 618 btsl $_EFER_LME, %eax 619 wrmsr 620 popl %edx 621 popl %ecx 622 623 /* Enable PAE and LA57 (if required) paging modes */ 624 movl $X86_CR4_PAE, %eax 625 cmpl $0, %edx 626 jz 1f 627 orl $X86_CR4_LA57, %eax 6281: 629 movl %eax, %cr4 630 631 /* Calculate address of paging_enabled() once we are executing in the trampoline */ 632 leal .Lpaging_enabled - trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_OFFSET(%ecx), %eax 633 634 /* Prepare the stack for far return to Long Mode */ 635 pushl $__KERNEL_CS 636 pushl %eax 637 638 /* Enable paging again */ 639 movl $(X86_CR0_PG | X86_CR0_PE), %eax 640 movl %eax, %cr0 641 642 lret 643SYM_CODE_END(trampoline_32bit_src) 644 645 .code64 646SYM_FUNC_START_LOCAL_NOALIGN(.Lpaging_enabled) 647 /* Return from the trampoline */ 648 jmp *%rdi 649SYM_FUNC_END(.Lpaging_enabled) 650 651 /* 652 * The trampoline code has a size limit. 653 * Make sure we fail to compile if the trampoline code grows 654 * beyond TRAMPOLINE_32BIT_CODE_SIZE bytes. 655 */ 656 .org trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_SIZE 657 658 .code32 659SYM_FUNC_START_LOCAL_NOALIGN(.Lno_longmode) 660 /* This isn't an x86-64 CPU, so hang intentionally, we cannot continue */ 6611: 662 hlt 663 jmp 1b 664SYM_FUNC_END(.Lno_longmode) 665 666#include "../../kernel/verify_cpu.S" 667 668 .data 669SYM_DATA_START_LOCAL(gdt64) 670 .word gdt_end - gdt - 1 671 .quad gdt - gdt64 672SYM_DATA_END(gdt64) 673 .balign 8 674SYM_DATA_START_LOCAL(gdt) 675 .word gdt_end - gdt - 1 676 .long 0 677 .word 0 678 .quad 0x00cf9a000000ffff /* __KERNEL32_CS */ 679 .quad 0x00af9a000000ffff /* __KERNEL_CS */ 680 .quad 0x00cf92000000ffff /* __KERNEL_DS */ 681 .quad 0x0080890000000000 /* TS descriptor */ 682 .quad 0x0000000000000000 /* TS continued */ 683SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end) 684 685#ifdef CONFIG_EFI_STUB 686SYM_DATA(image_offset, .long 0) 687#endif 688 689#ifdef CONFIG_EFI_MIXED 690SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0) 691SYM_DATA(efi_is64, .byte 1) 692 693#define ST32_boottime 60 // offsetof(efi_system_table_32_t, boottime) 694#define BS32_handle_protocol 88 // offsetof(efi_boot_services_32_t, handle_protocol) 695#define LI32_image_base 32 // offsetof(efi_loaded_image_32_t, image_base) 696 697 .text 698 .code32 699SYM_FUNC_START(efi32_pe_entry) 700/* 701 * efi_status_t efi32_pe_entry(efi_handle_t image_handle, 702 * efi_system_table_32_t *sys_table) 703 */ 704 705 pushl %ebp 706 movl %esp, %ebp 707 pushl %eax // dummy push to allocate loaded_image 708 709 pushl %ebx // save callee-save registers 710 pushl %edi 711 712 call verify_cpu // check for long mode support 713 testl %eax, %eax 714 movl $0x80000003, %eax // EFI_UNSUPPORTED 715 jnz 2f 716 717 call 1f 7181: pop %ebx 719 subl $1b, %ebx 720 721 /* Get the loaded image protocol pointer from the image handle */ 722 leal -4(%ebp), %eax 723 pushl %eax // &loaded_image 724 leal loaded_image_proto(%ebx), %eax 725 pushl %eax // pass the GUID address 726 pushl 8(%ebp) // pass the image handle 727 728 /* 729 * Note the alignment of the stack frame. 730 * sys_table 731 * handle <-- 16-byte aligned on entry by ABI 732 * return address 733 * frame pointer 734 * loaded_image <-- local variable 735 * saved %ebx <-- 16-byte aligned here 736 * saved %edi 737 * &loaded_image 738 * &loaded_image_proto 739 * handle <-- 16-byte aligned for call to handle_protocol 740 */ 741 742 movl 12(%ebp), %eax // sys_table 743 movl ST32_boottime(%eax), %eax // sys_table->boottime 744 call *BS32_handle_protocol(%eax) // sys_table->boottime->handle_protocol 745 addl $12, %esp // restore argument space 746 testl %eax, %eax 747 jnz 2f 748 749 movl 8(%ebp), %ecx // image_handle 750 movl 12(%ebp), %edx // sys_table 751 movl -4(%ebp), %esi // loaded_image 752 movl LI32_image_base(%esi), %esi // loaded_image->image_base 753 movl %ebx, %ebp // startup_32 for efi32_pe_stub_entry 754 /* 755 * We need to set the image_offset variable here since startup_32() will 756 * use it before we get to the 64-bit efi_pe_entry() in C code. 757 */ 758 subl %esi, %ebx 759 movl %ebx, image_offset(%ebp) // save image_offset 760 jmp efi32_pe_stub_entry 761 7622: popl %edi // restore callee-save registers 763 popl %ebx 764 leave 765 ret 766SYM_FUNC_END(efi32_pe_entry) 767 768 .section ".rodata" 769 /* EFI loaded image protocol GUID */ 770 .balign 4 771SYM_DATA_START_LOCAL(loaded_image_proto) 772 .long 0x5b1b31a1 773 .word 0x9562, 0x11d2 774 .byte 0x8e, 0x3f, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b 775SYM_DATA_END(loaded_image_proto) 776#endif 777 778/* 779 * Stack and heap for uncompression 780 */ 781 .bss 782 .balign 4 783SYM_DATA_LOCAL(boot_heap, .fill BOOT_HEAP_SIZE, 1, 0) 784 785SYM_DATA_START_LOCAL(boot_stack) 786 .fill BOOT_STACK_SIZE, 1, 0 787SYM_DATA_END_LABEL(boot_stack, SYM_L_LOCAL, boot_stack_end) 788 789/* 790 * Space for page tables (not in .bss so not zeroed) 791 */ 792 .section ".pgtable","aw",@nobits 793 .balign 4096 794SYM_DATA_LOCAL(pgtable, .fill BOOT_PGT_SIZE, 1, 0) 795 796/* 797 * The page table is going to be used instead of page table in the trampoline 798 * memory. 799 */ 800SYM_DATA_LOCAL(top_pgtable, .fill PAGE_SIZE, 1, 0) 801