From 43d045788f8438b15806ae0267b26e57687bc216 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Mon, 7 Feb 2022 15:26:30 -0700
Subject: [PATCH] Support calling kernel
---
asm/x86-unknown-none/gdt.asm | 2 +-
asm/x86-unknown-none/long_mode.asm | 12 +++---
asm/x86-unknown-none/memory_map.asm | 33 +++++++++++++++
asm/x86-unknown-none/stage2.asm | 49 +++++++++++++++++++++++
src/disk.rs | 2 +-
src/lib.rs | 62 +++++++++++++++++++++++++++--
src/paging.rs | 6 +--
7 files changed, 151 insertions(+), 15 deletions(-)
create mode 100644 asm/x86-unknown-none/memory_map.asm
diff --git a/asm/x86-unknown-none/gdt.asm b/asm/x86-unknown-none/gdt.asm
index 773139a..925954a 100644
--- a/asm/x86-unknown-none/gdt.asm
+++ b/asm/x86-unknown-none/gdt.asm
@@ -58,7 +58,7 @@ gdt_flag:
gdtr:
dw gdt.end + 1 ; size
- dd gdt ; offset
+ dq gdt ; offset
gdt:
.null equ $ - gdt
diff --git a/asm/x86-unknown-none/long_mode.asm b/asm/x86-unknown-none/long_mode.asm
index de5f802..3a01d21 100644
--- a/asm/x86-unknown-none/long_mode.asm
+++ b/asm/x86-unknown-none/long_mode.asm
@@ -9,16 +9,12 @@ long_mode:
; disable interrupts
cli
- ;disable paging
+ ; disable paging
mov eax, cr0
and eax, 0x7FFFFFFF
mov cr0, eax
- ;cr3 holds pointer to PML4
- mov eax, [.page_table]
- mov cr3, eax
-
- ;enable OSXSAVE, FXSAVE/FXRSTOR, Page Global, Page Address Extension, and Page Size Extension
+ ; enable OSXSAVE, FXSAVE/FXRSTOR, Page Global, Page Address Extension, and Page Size Extension
mov eax, cr4
or eax, 1 << 18 | 1 << 9 | 1 << 7 | 1 << 5 | 1 << 4
mov cr4, eax
@@ -32,6 +28,10 @@ long_mode:
or eax, 1 << 11 | 1 << 8 ; Set the Long-Mode-Enable and NXE bit.
wrmsr
+ ; set page table
+ mov eax, [.page_table]
+ mov cr3, eax
+
; enabling paging and protection simultaneously
mov eax, cr0
or eax, 1 << 31 | 1 << 16 | 1 ;Bit 31: Paging, Bit 16: write protect kernel, Bit 0: Protected Mode
diff --git a/asm/x86-unknown-none/memory_map.asm b/asm/x86-unknown-none/memory_map.asm
new file mode 100644
index 0000000..460ea27
--- /dev/null
+++ b/asm/x86-unknown-none/memory_map.asm
@@ -0,0 +1,33 @@
+SECTION .text
+USE16
+
+;Generate a memory map at 0x500 to 0x5000 (available memory not used for kernel or bootloader)
+memory_map:
+.start equ 0x0500
+.end equ 0x5000
+.length equ .end - .start
+
+ xor eax, eax
+ mov di, .start
+ mov ecx, .length / 4 ; moving 4 Bytes at once
+ cld
+ rep stosd
+
+ mov di, .start
+ mov edx, 0x534D4150
+ xor ebx, ebx
+.lp:
+ mov eax, 0xE820
+ mov ecx, 24
+
+ int 0x15
+ jc .done ; Error or finished
+
+ cmp ebx, 0
+ je .done ; Finished
+
+ add di, 24
+ cmp di, .end
+ jb .lp ; Still have buffer space
+.done:
+ ret
diff --git a/asm/x86-unknown-none/stage2.asm b/asm/x86-unknown-none/stage2.asm
index 7455820..69cfc4d 100644
--- a/asm/x86-unknown-none/stage2.asm
+++ b/asm/x86-unknown-none/stage2.asm
@@ -10,12 +10,17 @@ stage2.entry:
or al, 2
out 0x92, al
+ ; load memory map
+ ;TODO: rewrite this in Rust
+ call memory_map
+
mov dword [protected_mode.func], stage3.entry
jmp protected_mode.entry
%include "cpuid.asm"
%include "gdt.asm"
%include "long_mode.asm"
+%include "memory_map.asm"
%include "protected_mode.asm"
%include "thunk.asm"
@@ -37,9 +42,53 @@ stage3.entry:
xor eax, eax
mov al, [disk]
push eax
+ mov eax, kernel.entry
+ push eax
mov eax, [stage3 + 0x18]
call eax
.halt:
cli
hlt
jmp .halt
+
+kernel:
+.stack: dq 0
+.func: dq 0
+.args: dq 0
+
+.entry:
+ ; page_table: usize
+ mov eax, [esp + 4]
+ mov [long_mode.page_table], eax
+
+ ; stack: u64
+ mov eax, [esp + 8]
+ mov [.stack], eax
+ mov eax, [esp + 12]
+ mov [.stack + 4], eax
+
+ ; func: u64
+ mov eax, [esp + 16]
+ mov [.func], eax
+ mov eax, [esp + 20]
+ mov [.func + 4], eax
+
+ ; args: *const KernelArgs
+ mov eax, [esp + 24]
+ mov [.args], eax
+
+ mov eax, .inner
+ mov [long_mode.func], eax
+ jmp long_mode.entry
+
+USE64
+
+.inner:
+ mov rsp, [.stack]
+ mov rax, [.func]
+ mov rdi, [.args]
+ call rax
+.halt:
+ cli
+ hlt
+ jmp .halt
diff --git a/src/disk.rs b/src/disk.rs
index e6dcac8..bb8a320 100644
--- a/src/disk.rs
+++ b/src/disk.rs
@@ -44,7 +44,7 @@ impl Disk for DiskBios {
fn read_at(&mut self, block: u64, buffer: &mut [u8]) -> Result<usize> {
for (i, chunk) in buffer.chunks_mut(BLOCK_SIZE as usize).enumerate() {
unsafe {
- let mut dap = DiskAddressPacket::from_block(block);
+ let mut dap = DiskAddressPacket::from_block(block + i as u64);
ptr::write(DISK_ADDRESS_PACKET_ADDR as *mut DiskAddressPacket, dap);
let mut data = ThunkData::new();
diff --git a/src/lib.rs b/src/lib.rs
index dcb365d..e5571e3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -46,6 +46,8 @@ const DISK_BIOS_ADDR: usize = 0x1000; // 4096 bytes, ends at 0x1FFF
const THUNK_STACK_ADDR: usize = 0x7C00; // Grows downwards
const VGA_ADDR: usize = 0xB8000;
+const PHYS_OFFSET: u64 = 0xFFFF800000000000;
+
#[global_allocator]
static ALLOCATOR: LockedHeap = LockedHeap::empty();
@@ -53,10 +55,35 @@ static VGA: Mutex<Vga> = Mutex::new(
unsafe { Vga::new(VGA_ADDR, 80, 25) }
);
-static mut KERNEL_PHYS: u64 = 0;
+#[repr(packed)]
+pub struct KernelArgs {
+ kernel_base: u64,
+ kernel_size: u64,
+ stack_base: u64,
+ stack_size: u64,
+ env_base: u64,
+ env_size: u64,
+
+ /// The base 64-bit pointer to an array of saved RSDPs. It's up to the kernel (and possibly
+ /// userspace), to decide which RSDP to use. The buffer will be a linked list containing a
+ /// 32-bit relative (to this field) next, and the actual struct afterwards.
+ ///
+ /// This field can be NULL, and if so, the system has not booted with UEFI or in some other way
+ /// retrieved the RSDPs. The kernel or a userspace driver will thus try searching the BIOS
+ /// memory instead. On UEFI systems, searching is not guaranteed to actually work though.
+ acpi_rsdps_base: u64,
+ /// The size of the RSDPs region.
+ acpi_rsdps_size: u64,
+}
#[no_mangle]
pub unsafe extern "C" fn kstart(
+ kernel_entry: extern "C" fn(
+ page_table: usize,
+ stack: u64,
+ func: u64,
+ args: *const KernelArgs,
+ ) -> !,
boot_disk: usize,
thunk10: extern "C" fn(),
thunk13: extern "C" fn(),
@@ -98,6 +125,15 @@ pub unsafe extern "C" fn kstart(
println!("HEAP: {:X}:{:X}", heap_start, heap_size);
ALLOCATOR.lock().init(heap_start, heap_size);
+
+ let stack_size = 0x20000;
+ let stack_base = ALLOCATOR.alloc_zeroed(
+ Layout::from_size_align(stack_size, 4096).unwrap()
+ );
+ if stack_base.is_null() {
+ panic!("Failed to allocate memory for stack");
+ }
+
// Locate kernel on RedoxFS
let kernel = {
//TODO: ensure boot_disk is 8-bit
@@ -142,9 +178,27 @@ pub unsafe extern "C" fn kstart(
kernel
};
- println!("Kernel Phys: 0x{:X}", kernel.as_ptr() as u64);
- let page_phys = paging::paging_create(kernel.as_ptr() as u64);
- panic!("kernel entry not implemented");
+ println!("Kernel Phys: 0x{:X}", kernel.as_ptr() as usize);
+ let page_phys = paging::paging_create(kernel.as_ptr() as usize)
+ .expect("Failed to set up paging");
+
+ let args = KernelArgs {
+ kernel_base: kernel.as_ptr() as u64,
+ kernel_size: kernel.len() as u64,
+ stack_base: stack_base as u64,
+ stack_size: stack_size as u64,
+ env_base: 0,
+ env_size: 0,
+ acpi_rsdps_base: 0,
+ acpi_rsdps_size: 0,
+ };
+
+ kernel_entry(
+ page_phys,
+ args.stack_base + args.stack_size + PHYS_OFFSET,
+ *(kernel.as_ptr().add(0x18) as *const u64),
+ &args,
+ );
let mut modes = Vec::new();
{
diff --git a/src/paging.rs b/src/paging.rs
index 2f1e9d7..407433e 100644
--- a/src/paging.rs
+++ b/src/paging.rs
@@ -15,7 +15,7 @@ unsafe fn paging_allocate() -> Option<&'static mut [u64]> {
}
}
-pub unsafe fn paging_create(kernel_phys: u64) -> Option<u64> {
+pub unsafe fn paging_create(kernel_phys: usize) -> Option<usize> {
// Create PML4
let pml4 = paging_allocate()?;
@@ -67,12 +67,12 @@ pub unsafe fn paging_create(kernel_phys: u64) -> Option<u64> {
pdp_i as u64 * 0x4000_0000 +
pd_i as u64 * 0x20_0000 +
pt_i as u64 * 0x1000 +
- kernel_phys;
+ kernel_phys as u64;
pt[pt_i] = addr | 1 << 1 | 1;
}
}
}
}
- Some(pml4.as_ptr() as u64)
+ Some(pml4.as_ptr() as usize)
}
--
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