/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│ │vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│ ╞══════════════════════════════════════════════════════════════════════════════╡ │ Copyright 2021 Justine Alexandra Roberts Tunney │ │ │ │ Permission to use, copy, modify, and/or distribute this software for │ │ any purpose with or without fee is hereby granted, provided that the │ │ above copyright notice and this permission notice appear in all copies. │ │ │ │ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │ │ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │ │ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │ │ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │ │ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │ │ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │ │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │ │ PERFORMANCE OF THIS SOFTWARE. │ ╚─────────────────────────────────────────────────────────────────────────────*/ #include "libc/bits/bits.h" #include "libc/dce.h" #include "libc/macros.internal.h" #include "libc/nt/efi.h" #include "libc/nt/thunk/msabi.h" #include "libc/runtime/e820.internal.h" #include "libc/runtime/internal.h" #include "libc/runtime/pc.internal.h" #include "libc/runtime/runtime.h" #include "libc/str/str.h" /* TOOD: Why can't we change CR3? Could it really need PML5T? */ /* TOOD: Why does QEMU in UEFI mode take ten seconds to boot? */ struct EfiArgs { char *Args[0x400 / sizeof(char *)]; char ArgBlock[0xC00]; }; static const EFI_GUID kEfiLoadedImageProtocol = LOADED_IMAGE_PROTOCOL; /** * EFI Application Entrypoint. * * This entrypoint is mutually exclusive from WinMain since * Windows apps and EFI apps use the same PE binary format. * So if you want to trade away Windows so that you can use * UEFI instead of the normal BIOS boot process, do this: * * STATIC_YOINK("EfiMain"); * int main() { ... } * * You can use QEMU to test this, but please note that UEFI * goes thousands of times slower than the normal BIOS boot * * qemu-system-x86_64 \ * -bios OVMF.fd \ * -nographic \ * -net none \ * -drive format=raw,file=fat:rw:o/tool/viz * FS0: * deathstar.com * * @see libc/dce.h */ __msabi noasan EFI_STATUS EfiMain(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable) { int type, x87cw; struct mman *mm; uint32_t DescVersion; uintptr_t i, j, MapSize; struct EfiArgs *ArgBlock; EFI_LOADED_IMAGE *ImgInfo; EFI_MEMORY_DESCRIPTOR *Map; uintptr_t Args, MapKey, DescSize; uint64_t p, pe, cr4, *m, *pd, *sp, *pml4t, *pdt1, *pdt2, *pdpt1, *pdpt2; extern char __os asm("__hostos"); __os = METAL; /* * Allocates and clears PC-compatible memory and copies image. */ SystemTable->BootServices->AllocatePages( AllocateAddress, EfiConventionalMemory, MAX(2 * 1024 * 1024, 1024 * 1024 + (_end - _base)) / 4096, 0); SystemTable->BootServices->SetMem(0, 0x80000, 0); SystemTable->BootServices->CopyMem((void *)(1024 * 1024), _base, _end - _base); /* * Converts UEFI shell arguments to argv. */ ArgBlock = (struct EfiArgs *)0x7e000; SystemTable->BootServices->HandleProtocol(ImageHandle, &kEfiLoadedImageProtocol, &ImgInfo); Args = GetDosArgv(ImgInfo->LoadOptions, ArgBlock->ArgBlock, sizeof(ArgBlock->ArgBlock), ArgBlock->Args, ARRAYLEN(ArgBlock->Args)); /* * Asks UEFI which parts of our RAM we're allowed to use. */ Map = NULL; MapSize = 0; SystemTable->BootServices->GetMemoryMap(&MapSize, Map, &MapKey, &DescSize, &DescVersion); SystemTable->BootServices->AllocatePool(EfiLoaderData, MapSize, Map); SystemTable->BootServices->GetMemoryMap(&MapSize, Map, &MapKey, &DescSize, &DescVersion); asm("xor\t%0,%0" : "=r"(mm)); /* gcc assumes null isn't mapped */ for (j = i = 0; i < MapSize / sizeof(EFI_MEMORY_DESCRIPTOR); ++i) { if (Map[i].Type != EfiConventionalMemory) continue; mm->e820[j].addr = Map[i].PhysicalStart; mm->e820[j].size = Map[i].NumberOfPages * 4096; mm->e820[j].type = kMemoryUsable; ++j; } SystemTable->BootServices->FreePool(Map); /* * Sets up page tables. */ pd = (uint64_t *)0x79000; pdt1 = (uint64_t *)0x7b000; pdt2 = (uint64_t *)0x7a000; pdpt1 = (uint64_t *)0x7d000; pdpt2 = (uint64_t *)0x7c000; pml4t = (uint64_t *)0x7e000; for (i = 0; i < 512; ++i) { pd[i] = 0x1000 * i + PAGE_V + PAGE_RW; } pdt1[0] = (intptr_t)pd + PAGE_V + PAGE_RW; pdt2[0] = (intptr_t)pd + PAGE_V + PAGE_RW; pdpt1[0] = (intptr_t)pdt1 + PAGE_V + PAGE_RW; pdpt2[0] = (intptr_t)pdt2 + PAGE_V + PAGE_RW; pml4t[0] = (intptr_t)pdpt1 + PAGE_V + PAGE_RW; pml4t[256] = (intptr_t)pdpt2 + PAGE_V + PAGE_RW; __map_phdrs(mm, pml4t, 1024 * 1024); /* * Asks UEFI to handover control? */ SystemTable->BootServices->ExitBootServices(ImageHandle, MapKey); /* * Launches program. */ asm volatile("fldcw\t%3\n\t" "mov\t%4,%%cr3\n\t" ".weak\tape_stack_vaddr\n\t" ".weak\tape_stack_memsz\n\t" "movabs\t$ape_stack_vaddr,%%rsp\n\t" "add\t$ape_stack_memsz,%%rsp\n\t" "push\t$0\n\t" /* auxv[1][1] */ "push\t$0\n\t" /* auxv[1][0] */ "push\t(%1)\n\t" /* auxv[0][1] */ "push\t$31\n\t" /* auxv[0][0] AT_EXECFN */ "push\t$0\n\t" /* envp[0] */ "sub\t%2,%%rsp\n\t" "mov\t%%rsp,%%rdi\n\t" "rep movsb\n\t" /* argv */ "push\t%0\n\t" /* argc */ "xor\t%%edi,%%edi\n\t" "xor\t%%eax,%%eax\n\t" "xor\t%%ebx,%%ebx\n\t" "xor\t%%ecx,%%ecx\n\t" "xor\t%%edx,%%edx\n\t" "xor\t%%edi,%%edi\n\t" "xor\t%%esi,%%esi\n\t" "xor\t%%ebp,%%ebp\n\t" "xor\t%%r8d,%%r8d\n\t" "xor\t%%r9d,%%r9d\n\t" "xor\t%%r10d,%%r10d\n\t" "xor\t%%r11d,%%r11d\n\t" "xor\t%%r12d,%%r12d\n\t" "xor\t%%r13d,%%r13d\n\t" "xor\t%%r14d,%%r14d\n\t" "xor\t%%r15d,%%r15d\n\t" ".weak\t_start\n\t" "jmp\t_start" : /* no outputs */ : "a"(Args), "S"(ArgBlock->Args), "c"((Args + 1) * 8), "m"(x87cw), "r"(pml4t) : "memory"); unreachable; }