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Bootloader: Locate the kernel's data segment and clear it.

This was a constant source of stupid bugs and I kept postponing it because
I wasn't in the mood to write assembly code. Until now! :^)
This commit is contained in:
Andreas Kling 2019-02-06 16:02:10 +01:00
parent 781f216676
commit a1b63bb6d4
22 changed files with 54 additions and 83 deletions

View file

@ -24,11 +24,6 @@ BochsVGADevice& BochsVGADevice::the()
return *s_the;
}
void BochsVGADevice::initialize_statics()
{
s_the = nullptr;
}
BochsVGADevice::BochsVGADevice()
{
s_the = this;

View file

@ -10,7 +10,6 @@ class BochsVGADevice {
AK_MAKE_ETERNAL
public:
static BochsVGADevice& the();
static void initialize_statics();
BochsVGADevice();

View file

@ -25,9 +25,13 @@ boot:
mov ax, 0x2401
int 0x15
mov bx, 0x1000
; HACK: Load the ELF kernel at 0xf000. Assuming that the first
; LOAD header has a file offset of 0x1000, this puts _start
; at 0x10000 which we jump to later.
; This is all quite rickety.
mov bx, 0xf00
mov es, bx
xor bx, bx ; Load kernel @ 0x10000
xor bx, bx
mov cx, word [cur_lba]
.sector_loop:
@ -65,6 +69,53 @@ boot:
xor al, al
out dx, al
; Let's look at the ELF header.
mov bx, 0xf00
mov fs, bx
cmp [fs:0], dword 0x464c457f ; ELF magic: { 0x7f "ELF" }
jne fug
cmp [fs:24], dword 0x10000 ; Entry should be 0x10000
jne fug
mov ebx, dword [fs:28] ; EBX <- program header table
mov ecx, dword [fs:44] ; ECX <- program header count
; Let's find the BSS and clear it.
parse_program_header:
cmp [fs:ebx], dword 0x1 ; Is Load segment?
jne .next
cmp [fs:ebx+24], dword 0x6 ; Is read+write but not execute?
jne .next
mov edi, [fs:ebx+8] ; EDI <- p_vaddr
add edi, [fs:ebx+16] ; skip over 'p_filesz' bytes (leave them intact)
push ecx
sub edi, [fs:ebx+16] ; skip over 'p_filesz' bytes (see above)
; Since we're in 16-bit real mode, create a segment address.
mov eax, edi
shr eax, 4
mov es, ax
and edi, 0xf
mov ecx, [fs:ebx+20] ; ECX <- p_memsz
xor al, al
rep stosb
pop ecx
.next:
add ebx, 32
loop parse_program_header
; Okay we're all set to go!
lets_go:
lgdt [cs:test_gdt_ptr]
mov eax, cr0
@ -182,7 +233,7 @@ convert_lba_to_chs:
ret
cur_lba:
dw 9
dw 1
sectors_per_track:
dw 18
heads:

View file

@ -23,13 +23,6 @@ HashTable<Inode*>& all_inodes()
return *s_inode_set;
}
void FS::initialize_globals()
{
s_lastFileSystemID = 0;
s_fs_map = nullptr;
s_inode_set = nullptr;
}
FS::FS()
: m_fsid(++s_lastFileSystemID)
{

View file

@ -23,7 +23,6 @@ class VMObject;
class FS : public Retainable<FS> {
public:
static void initialize_globals();
virtual ~FS();
unsigned fsid() const { return m_fsid; }

View file

@ -12,11 +12,6 @@ PTYMultiplexer& PTYMultiplexer::the()
return *s_the;
}
void PTYMultiplexer::initialize_statics()
{
s_the = nullptr;
}
PTYMultiplexer::PTYMultiplexer()
: CharacterDevice(5, 2)
{

View file

@ -13,7 +13,6 @@ public:
virtual ~PTYMultiplexer() override;
static PTYMultiplexer& the();
static void initialize_statics();
// ^CharacterDevice
virtual RetainPtr<FileDescriptor> open(int& error, int options) override;

View file

@ -12,11 +12,6 @@
void Process::initialize_gui_statics()
{
Font::initialize();
WSMessageLoop::initialize();
WSWindowManager::initialize();
WSScreen::initialize();
new WSMessageLoop;
}

View file

@ -19,12 +19,6 @@ VFS& VFS::the()
return *s_the;
}
void VFS::initialize_globals()
{
s_the = nullptr;
FS::initialize_globals();
}
VFS::VFS()
{
#ifdef VFS_DEBUG

View file

@ -39,8 +39,6 @@ class VFS;
class VFS {
AK_MAKE_ETERNAL
public:
static void initialize_globals();
class Mount {
public:
Mount(InodeIdentifier host, RetainPtr<FS>&&);

View file

@ -151,8 +151,6 @@ void init()
gdt_init();
idt_init();
PTYMultiplexer::initialize_statics();
VFS::initialize_globals();
vfs = new VFS;
keyboard = new Keyboard;
@ -169,10 +167,6 @@ void init()
kprintf("Starting Serenity Operating System...\n");
MemoryManager::initialize();
StringImpl::initialize_globals();
BochsVGADevice::initialize_statics();
PIT::initialize();
memset(&system, 0, sizeof(system));