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https://github.com/LadybirdBrowser/ladybird.git
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7e94b090fe
This implements a simple bootloader that is capable of loading ELF64 kernel images. It does this by using QEMU/GRUB to load the kernel image from disk and pass it to our bootloader as a Multiboot module. The bootloader then parses the ELF image and sets it up appropriately. The kernel's entry point is a C++ function with architecture-native code. Co-authored-by: Liav A <liavalb@gmail.com>
92 lines
2.1 KiB
C++
92 lines
2.1 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/StdLib.h>
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extern "C" {
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void* memcpy(void* dest_ptr, const void* src_ptr, size_t n)
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{
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size_t dest = (size_t)dest_ptr;
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size_t src = (size_t)src_ptr;
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// FIXME: Support starting at an unaligned address.
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if (!(dest & 0x3) && !(src & 0x3) && n >= 12) {
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size_t size_ts = n / sizeof(size_t);
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#if ARCH(I386)
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asm volatile(
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"rep movsl\n"
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: "=S"(src), "=D"(dest)
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: "S"(src), "D"(dest), "c"(size_ts)
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: "memory");
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#else
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asm volatile(
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"rep movsq\n"
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: "=S"(src), "=D"(dest)
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: "S"(src), "D"(dest), "c"(size_ts)
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: "memory");
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#endif
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n -= size_ts * sizeof(size_t);
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if (n == 0)
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return dest_ptr;
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}
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asm volatile(
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"rep movsb\n" ::"S"(src), "D"(dest), "c"(n)
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: "memory");
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return dest_ptr;
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}
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void* memmove(void* dest, const void* src, size_t n)
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{
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if (dest < src)
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return memcpy(dest, src, n);
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u8* pd = (u8*)dest;
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const u8* ps = (const u8*)src;
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for (pd += n, ps += n; n--;)
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*--pd = *--ps;
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return dest;
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}
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void* memset(void* dest_ptr, int c, size_t n)
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{
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size_t dest = (size_t)dest_ptr;
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// FIXME: Support starting at an unaligned address.
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if (!(dest & 0x3) && n >= 12) {
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size_t size_ts = n / sizeof(size_t);
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size_t expanded_c = explode_byte((u8)c);
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#if ARCH(I386)
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asm volatile(
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"rep stosl\n"
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: "=D"(dest)
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: "D"(dest), "c"(size_ts), "a"(expanded_c)
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: "memory");
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#else
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asm volatile(
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"rep stosq\n"
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: "=D"(dest)
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: "D"(dest), "c"(size_ts), "a"(expanded_c)
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: "memory");
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#endif
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n -= size_ts * sizeof(size_t);
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if (n == 0)
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return dest_ptr;
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}
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asm volatile(
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"rep stosb\n"
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: "=D"(dest), "=c"(n)
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: "0"(dest), "1"(n), "a"(c)
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: "memory");
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return dest_ptr;
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}
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size_t strlen(const char* str)
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{
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size_t len = 0;
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while (*(str++))
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++len;
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return len;
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}
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}
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