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Kernel: Introduce basic pre-kernel environment

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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>
This commit is contained in:
Gunnar Beutner 2021-07-18 14:47:32 +02:00 • committed by Andreas Kling
parent 357ddd393e
commit 7e94b090fe
30 changed files with 1207 additions and 181 deletions
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82
Kernel/StdLib.cpp
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@ -236,48 +236,6 @@ bool copy_from_user(void* dest_ptr, const void* src_ptr, size_t n)
return true;
}
void* memcpy(void* dest_ptr, const void* src_ptr, size_t n)
{
size_t dest = (size_t)dest_ptr;
size_t src = (size_t)src_ptr;
// FIXME: Support starting at an unaligned address.
if (!(dest & 0x3) && !(src & 0x3) && n >= 12) {
size_t size_ts = n / sizeof(size_t);
#if ARCH(I386)
asm volatile(
"rep movsl\n"
: "=S"(src), "=D"(dest)
: "S"(src), "D"(dest), "c"(size_ts)
: "memory");
#else
asm volatile(
"rep movsq\n"
: "=S"(src), "=D"(dest)
: "S"(src), "D"(dest), "c"(size_ts)
: "memory");
#endif
n -= size_ts * sizeof(size_t);
if (n == 0)
return dest_ptr;
}
asm volatile(
"rep movsb\n" ::"S"(src), "D"(dest), "c"(n)
: "memory");
return dest_ptr;
}
void* memmove(void* dest, const void* src, size_t n)
{
if (dest < src)
return memcpy(dest, src, n);
u8* pd = (u8*)dest;
const u8* ps = (const u8*)src;
for (pd += n, ps += n; n--;)
*--pd = *--ps;
return dest;
}
const void* memmem(const void* haystack, size_t haystack_length, const void* needle, size_t needle_length)
{
return AK::memmem(haystack, haystack_length, needle, needle_length);
@ -297,46 +255,6 @@ const void* memmem(const void* haystack, size_t haystack_length, const void* nee
return true;
}
void* memset(void* dest_ptr, int c, size_t n)
{
size_t dest = (size_t)dest_ptr;
// FIXME: Support starting at an unaligned address.
if (!(dest & 0x3) && n >= 12) {
size_t size_ts = n / sizeof(size_t);
size_t expanded_c = explode_byte((u8)c);
#if ARCH(I386)
asm volatile(
"rep stosl\n"
: "=D"(dest)
: "D"(dest), "c"(size_ts), "a"(expanded_c)
: "memory");
#else
asm volatile(
"rep stosq\n"
: "=D"(dest)
: "D"(dest), "c"(size_ts), "a"(expanded_c)
: "memory");
#endif
n -= size_ts * sizeof(size_t);
if (n == 0)
return dest_ptr;
}
asm volatile(
"rep stosb\n"
: "=D"(dest), "=c"(n)
: "0"(dest), "1"(n), "a"(c)
: "memory");
return dest_ptr;
}
size_t strlen(const char* str)
{
size_t len = 0;
while (*(str++))
++len;
return len;
}
size_t strnlen(const char* str, size_t maxlen)
{
size_t len = 0;