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Formatting, LF and RISC-V kmain

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This commit is contained in:
Erin 2023-03-19 13:40:08 +01:00 committed by ondra05
parent e3ce700295
commit cef19a8fe4
3 changed files with 388 additions and 396 deletions
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536
kernel/src/arch/riscv64/memory.rs
View file

@ -1,268 +1,268 @@
use core::num;
use alloc::boxed::Box;
use spin::{Mutex, Once};
use crate::memory::{MemoryManager, PhysicalAddress, VirtualAddress};
use super::PAGE_SIZE;
pub enum PageSize {
Size4KiB,
Size2MiB,
Size1GiB,
// FIXME: SV48 support
// Size512GiB,
// FIXME: SV57 support
// Size256TiB,
}
impl PageSize {
fn level(&self) -> usize {
match self {
PageSize::Size4KiB => 0,
PageSize::Size2MiB => 1,
PageSize::Size1GiB => 2,
// FIXME: SV48 and SV57 support
}
}
}
pub struct PageTable {
entries: [PageEntry; 512]
}
impl PageTable {
/// Walk the page table to convert a virtual address to a physical address.
/// If a page fault would occur, this returns None. Otherwise, it returns the physical address.
pub fn virt_to_phys(&self, vaddr: VirtualAddress) -> Option<PhysicalAddress> {
let vpn = vaddr.vpns();
let mut v = &self.entries[vpn[2]];
for i in (0..=2).rev() {
if v.is_invalid() {
// This is an invalid entry, page fault.
break;
} else if v.is_leaf() {
// In RISC-V, a leaf can be at any level.
// The offset mask masks off the PPN. Each PPN is 9 bits and they start at bit #12.
// So, our formula 12 + i * 9
let off_mask = (1 << (12 + i * 9)) - 1;
let vaddr_pgoff = vaddr.as_addr() & off_mask;
let addr = ((v.entry() << 2) as usize) & !off_mask;
return Some((addr | vaddr_pgoff).into());
}
// Set v to the next entry which is pointed to by this entry.
// However, the address was shifted right by 2 places when stored in the page table
// entry, so we shift it left to get it back into place.
let entry = v.addr().as_ptr::<PageEntry>();
// We do i - 1 here, however we should get None or Some() above
// before we do 0 - 1 = -1.
v = unsafe { entry.add(vpn[i - 1]).as_ref().unwrap() };
}
// If we get here, we've exhausted all valid tables and haven't
// found a leaf.
None
}
/// Maps a virtual address to a physical address
/// flags should contain only the following:
/// Read, Write, Execute, User, and/or Global
/// flags MUST include one or more of the following:
/// Read, Write, Execute
/// The valid bit automatically gets added
pub fn map(&mut self, vaddr: VirtualAddress, paddr: PhysicalAddress, flags: PageEntryFlags, page_size: PageSize) {
assert!(flags as usize & 0xe != 0);
let vpn = vaddr.vpns();
let ppn = paddr.ppns();
let level = page_size.level();
let mut v = &mut self.entries[vpn[2]];
// Now, we're going to traverse the page table and set the bits properly. We expect the root
// to be valid, however we're required to create anything beyond the root
for i in (level..2).rev() {
if v.is_invalid() {
let mut mm = MEMORY_MANAGER.get().unwrap().lock();
let page = mm.zallocate_pages(1).unwrap().as_addr();
v.set_entry((page as usize >> 2) | PageEntryFlags::Valid as usize);
}
let entry = v.addr().as_mut_ptr::<PageEntry>();
v = unsafe { entry.add(vpn[i]).as_mut().unwrap() };
}
// When we get here, we should be at VPN[0] and v should be pointing to our entry.
// The entry structure is Figure 4.18 in the RISC-V Privileged Specification
let entry = (ppn[2] << 28) as usize // PPN[2] = [53:28]
| (ppn[1] << 19) as usize // PPN[1] = [27:19]
| (ppn[0] << 10) as usize // PPN[0] = [18:10]
| flags as usize // Specified bits, such as User, Read, Write, etc.
| PageEntryFlags::Valid as usize;
v.set_entry(entry);
}
/// Identity maps a page of memory
pub fn identity_map(&mut self, addr: PhysicalAddress, flags: PageEntryFlags, page_size: PageSize) {
// log::debug!("identity mapped {addr}");
self.map(addr.as_addr().into(), addr, flags, page_size);
}
/// Identity maps a range of contiguous memory
/// This assumes that start <= end
pub fn identity_map_range(&mut self, start: PhysicalAddress, end: PhysicalAddress, flags: PageEntryFlags) {
log::debug!("start: {start}, end: {end}");
let mut mem_addr = start.as_addr() & !(PAGE_SIZE - 1);
let num_pages = (align_val(end.as_addr(), 12) - mem_addr - 1) / PAGE_SIZE + 1;
for _ in 0..num_pages {
// FIXME: we can merge these page entries if possible into Size2MiB or larger entries
self.identity_map(mem_addr.into(), flags, PageSize::Size4KiB);
mem_addr += 1 << 12;
}
}
/// Unmaps a page of memory at vaddr
pub fn unmap(&mut self, vaddr: VirtualAddress) {
let vpn = vaddr.vpns();
// Now, we're going to traverse the page table and clear the bits
let mut v = &mut self.entries[vpn[2]];
for i in (0..2).rev() {
if v.is_invalid() {
// This is an invalid entry, page is already unmapped
return;
} else if v.is_leaf() {
// This is a leaf, which can be at any level
// In order to make this page unmapped, we need to clear the entry
v.set_entry(0);
return;
}
let entry = v.addr().as_mut_ptr::<PageEntry>();
v = unsafe { entry.add(vpn[i]).as_mut().unwrap() };
}
// If we're here this is an unmapped page
return;
}
/// Unmaps a range of contiguous memory
/// This assumes that start <= end
pub fn unmap_range(&mut self, start: VirtualAddress, end: VirtualAddress) {
let mut mem_addr = start.as_addr() & !(PAGE_SIZE - 1);
let num_pages = (align_val(end.as_addr(), 12) - mem_addr) / PAGE_SIZE;
for _ in 0..num_pages {
self.unmap(mem_addr.into());
mem_addr += 1 << 12;
}
}
/// Frees all memory associated with a table.
/// NOTE: This does NOT free the table directly. This must be freed manually.
fn destroy(&mut self) {
for entry in &mut self.entries {
entry.destroy()
}
}
}
#[repr(usize)]
#[derive(Clone, Copy, Debug)]
pub enum PageEntryFlags {
None = 0,
Valid = 1,
Read = 1 << 1,
Write = 1 << 2,
Execute = 1 << 3,
User = 1 << 4,
Global = 1 << 5,
Access = 1 << 6,
Dirty = 1 << 7,
// for convenience
ReadWrite = Self::Read as usize | Self::Write as usize,
ReadExecute = Self::Read as usize | Self::Execute as usize,
ReadWriteExecute = Self::Read as usize | Self::Write as usize | Self::Execute as usize,
UserReadWrite = Self::User as usize | Self::ReadWrite as usize,
UserReadExecute = Self::User as usize | Self::ReadExecute as usize,
UserReadWriteExecute = Self::User as usize | Self::ReadWriteExecute as usize,
}
struct PageEntry(usize);
impl PageEntry {
fn is_valid(&self) -> bool {
self.0 & PageEntryFlags::Valid as usize != 0
}
fn is_invalid(&self) -> bool {
!self.is_valid()
}
fn is_leaf(&self) -> bool {
self.0 & PageEntryFlags::ReadWriteExecute as usize != 0
}
fn is_branch(&self) -> bool {
!self.is_leaf()
}
fn entry(&self) -> usize {
self.0
}
fn set_entry(&mut self, entry: usize) {
self.0 = entry;
}
fn clear_flag(&mut self, flag: PageEntryFlags) {
self.0 &= !(flag as usize);
}
fn set_flag(&mut self, flag: PageEntryFlags) {
self.0 |= flag as usize;
}
fn addr(&self) -> PhysicalAddress {
((self.entry() as usize & !0x3ff) << 2).into()
}
fn destroy(&mut self) {
if self.is_valid() && self.is_branch() {
// This is a valid entry so drill down and free
let memaddr = self.addr();
let table = memaddr.as_mut_ptr::<PageTable>();
unsafe {
(*table).destroy();
let mut mm = MEMORY_MANAGER.get().unwrap().lock();
mm.deallocate_pages(memaddr.into(), 0);
}
}
}
}
// FIXME: PageTable should be integrated into MemoryManager *somehow*
pub static MEMORY_MANAGER: Once<Mutex<MemoryManager>> = Once::new();
pub static PAGE_TABLE: Once<Mutex<PhysicalAddress>> = Once::new();
pub fn init(start_addr: PhysicalAddress, page_count: usize) {
let mut memory_manager = MemoryManager::new();
unsafe {
memory_manager.add_range(start_addr, page_count);
PAGE_TABLE.call_once(|| Mutex::new(memory_manager.zallocate_pages(0).unwrap()));
}
MEMORY_MANAGER.call_once(|| Mutex::new(memory_manager));
}
/// Align (set to a multiple of some power of two)
/// This function always rounds up.
fn align_val(val: usize, order: usize) -> usize {
let o = (1 << order) - 1;
(val + o) & !o
}
use core::num;
use alloc::boxed::Box;
use spin::{Mutex, Once};
use crate::memory::{MemoryManager, PhysicalAddress, VirtualAddress};
use super::PAGE_SIZE;
pub enum PageSize {
Size4KiB,
Size2MiB,
Size1GiB,
// FIXME: SV48 support
// Size512GiB,
// FIXME: SV57 support
// Size256TiB,
}
impl PageSize {
fn level(&self) -> usize {
match self {
PageSize::Size4KiB => 0,
PageSize::Size2MiB => 1,
PageSize::Size1GiB => 2,
// FIXME: SV48 and SV57 support
}
}
}
pub struct PageTable {
entries: [PageEntry; 512]
}
impl PageTable {
/// Walk the page table to convert a virtual address to a physical address.
/// If a page fault would occur, this returns None. Otherwise, it returns the physical address.
pub fn virt_to_phys(&self, vaddr: VirtualAddress) -> Option<PhysicalAddress> {
let vpn = vaddr.vpns();
let mut v = &self.entries[vpn[2]];
for i in (0..=2).rev() {
if v.is_invalid() {
// This is an invalid entry, page fault.
break;
} else if v.is_leaf() {
// In RISC-V, a leaf can be at any level.
// The offset mask masks off the PPN. Each PPN is 9 bits and they start at bit #12.
// So, our formula 12 + i * 9
let off_mask = (1 << (12 + i * 9)) - 1;
let vaddr_pgoff = vaddr.as_addr() & off_mask;
let addr = ((v.entry() << 2) as usize) & !off_mask;
return Some((addr | vaddr_pgoff).into());
}
// Set v to the next entry which is pointed to by this entry.
// However, the address was shifted right by 2 places when stored in the page table
// entry, so we shift it left to get it back into place.
let entry = v.addr().as_ptr::<PageEntry>();
// We do i - 1 here, however we should get None or Some() above
// before we do 0 - 1 = -1.
v = unsafe { entry.add(vpn[i - 1]).as_ref().unwrap() };
}
// If we get here, we've exhausted all valid tables and haven't
// found a leaf.
None
}
/// Maps a virtual address to a physical address
/// flags should contain only the following:
/// Read, Write, Execute, User, and/or Global
/// flags MUST include one or more of the following:
/// Read, Write, Execute
/// The valid bit automatically gets added
pub fn map(&mut self, vaddr: VirtualAddress, paddr: PhysicalAddress, flags: PageEntryFlags, page_size: PageSize) {
assert!(flags as usize & 0xe != 0);
let vpn = vaddr.vpns();
let ppn = paddr.ppns();
let level = page_size.level();
let mut v = &mut self.entries[vpn[2]];
// Now, we're going to traverse the page table and set the bits properly. We expect the root
// to be valid, however we're required to create anything beyond the root
for i in (level..2).rev() {
if v.is_invalid() {
let mut mm = MEMORY_MANAGER.get().unwrap().lock();
let page = mm.zallocate_pages(1).unwrap().as_addr();
v.set_entry((page as usize >> 2) | PageEntryFlags::Valid as usize);
}
let entry = v.addr().as_mut_ptr::<PageEntry>();
v = unsafe { entry.add(vpn[i]).as_mut().unwrap() };
}
// When we get here, we should be at VPN[0] and v should be pointing to our entry.
// The entry structure is Figure 4.18 in the RISC-V Privileged Specification
let entry = (ppn[2] << 28) as usize // PPN[2] = [53:28]
| (ppn[1] << 19) as usize // PPN[1] = [27:19]
| (ppn[0] << 10) as usize // PPN[0] = [18:10]
| flags as usize // Specified bits, such as User, Read, Write, etc.
| PageEntryFlags::Valid as usize;
v.set_entry(entry);
}
/// Identity maps a page of memory
pub fn identity_map(&mut self, addr: PhysicalAddress, flags: PageEntryFlags, page_size: PageSize) {
// log::debug!("identity mapped {addr}");
self.map(addr.as_addr().into(), addr, flags, page_size);
}
/// Identity maps a range of contiguous memory
/// This assumes that start <= end
pub fn identity_map_range(&mut self, start: PhysicalAddress, end: PhysicalAddress, flags: PageEntryFlags) {
log::debug!("start: {start}, end: {end}");
let mut mem_addr = start.as_addr() & !(PAGE_SIZE - 1);
let num_pages = (align_val(end.as_addr(), 12) - mem_addr - 1) / PAGE_SIZE + 1;
for _ in 0..num_pages {
// FIXME: we can merge these page entries if possible into Size2MiB or larger entries
self.identity_map(mem_addr.into(), flags, PageSize::Size4KiB);
mem_addr += 1 << 12;
}
}
/// Unmaps a page of memory at vaddr
pub fn unmap(&mut self, vaddr: VirtualAddress) {
let vpn = vaddr.vpns();
// Now, we're going to traverse the page table and clear the bits
let mut v = &mut self.entries[vpn[2]];
for i in (0..2).rev() {
if v.is_invalid() {
// This is an invalid entry, page is already unmapped
return;
} else if v.is_leaf() {
// This is a leaf, which can be at any level
// In order to make this page unmapped, we need to clear the entry
v.set_entry(0);
return;
}
let entry = v.addr().as_mut_ptr::<PageEntry>();
v = unsafe { entry.add(vpn[i]).as_mut().unwrap() };
}
// If we're here this is an unmapped page
return;
}
/// Unmaps a range of contiguous memory
/// This assumes that start <= end
pub fn unmap_range(&mut self, start: VirtualAddress, end: VirtualAddress) {
let mut mem_addr = start.as_addr() & !(PAGE_SIZE - 1);
let num_pages = (align_val(end.as_addr(), 12) - mem_addr) / PAGE_SIZE;
for _ in 0..num_pages {
self.unmap(mem_addr.into());
mem_addr += 1 << 12;
}
}
/// Frees all memory associated with a table.
/// NOTE: This does NOT free the table directly. This must be freed manually.
fn destroy(&mut self) {
for entry in &mut self.entries {
entry.destroy()
}
}
}
#[repr(usize)]
#[derive(Clone, Copy, Debug)]
pub enum PageEntryFlags {
None = 0,
Valid = 1,
Read = 1 << 1,
Write = 1 << 2,
Execute = 1 << 3,
User = 1 << 4,
Global = 1 << 5,
Access = 1 << 6,
Dirty = 1 << 7,
// for convenience
ReadWrite = Self::Read as usize | Self::Write as usize,
ReadExecute = Self::Read as usize | Self::Execute as usize,
ReadWriteExecute = Self::Read as usize | Self::Write as usize | Self::Execute as usize,
UserReadWrite = Self::User as usize | Self::ReadWrite as usize,
UserReadExecute = Self::User as usize | Self::ReadExecute as usize,
UserReadWriteExecute = Self::User as usize | Self::ReadWriteExecute as usize,
}
struct PageEntry(usize);
impl PageEntry {
fn is_valid(&self) -> bool {
self.0 & PageEntryFlags::Valid as usize != 0
}
fn is_invalid(&self) -> bool {
!self.is_valid()
}
fn is_leaf(&self) -> bool {
self.0 & PageEntryFlags::ReadWriteExecute as usize != 0
}
fn is_branch(&self) -> bool {
!self.is_leaf()
}
fn entry(&self) -> usize {
self.0
}
fn set_entry(&mut self, entry: usize) {
self.0 = entry;
}
fn clear_flag(&mut self, flag: PageEntryFlags) {
self.0 &= !(flag as usize);
}
fn set_flag(&mut self, flag: PageEntryFlags) {
self.0 |= flag as usize;
}
fn addr(&self) -> PhysicalAddress {
((self.entry() as usize & !0x3ff) << 2).into()
}
fn destroy(&mut self) {
if self.is_valid() && self.is_branch() {
// This is a valid entry so drill down and free
let memaddr = self.addr();
let table = memaddr.as_mut_ptr::<PageTable>();
unsafe {
(*table).destroy();
let mut mm = MEMORY_MANAGER.get().unwrap().lock();
mm.deallocate_pages(memaddr.into(), 0);
}
}
}
}
// FIXME: PageTable should be integrated into MemoryManager *somehow*
pub static MEMORY_MANAGER: Once<Mutex<MemoryManager>> = Once::new();
pub static PAGE_TABLE: Once<Mutex<PhysicalAddress>> = Once::new();
pub fn init(start_addr: PhysicalAddress, page_count: usize) {
let mut memory_manager = MemoryManager::new();
unsafe {
memory_manager.add_range(start_addr, page_count);
PAGE_TABLE.call_once(|| Mutex::new(memory_manager.zallocate_pages(0).unwrap()));
}
MEMORY_MANAGER.call_once(|| Mutex::new(memory_manager));
}
/// Align (set to a multiple of some power of two)
/// This function always rounds up.
fn align_val(val: usize, order: usize) -> usize {
let o = (1 << order) - 1;
(val + o) & !o
}

65
kernel/src/arch/riscv64/memory_regions.s
View file

@ -1,35 +1,30 @@
.section .rodata
.global TEXT_START
TEXT_START: .quad _text_start
.global TEXT_END
TEXT_END: .quad _text_end
.global RODATA_START
RODATA_START: .quad _rodata_start
.global RODATA_END
RODATA_END: .quad _rodata_end
.global DATA_START
DATA_START: .quad _data_start
.global DATA_END
DATA_END: .quad _data_end
.global SDATA_START
SDATA_START: .quad _sdata_start
.global SDATA_END
SDATA_END: .quad _sdata_end
.global BSS_START
BSS_START: .quad _bss_start
.global BSS_END
BSS_END: .quad _bss_end
.global INITIAL_KERNEL_HEAP_START
INITIAL_KERNEL_HEAP_START: .quad _initial_kernel_heap_start
.global INITIAL_KERNEL_HEAP_SIZE
INITIAL_KERNEL_HEAP_SIZE: .quad _initial_kernel_heap_size
.global USABLE_MEMORY_START
USABLE_MEMORY_START: .quad _usable_memory_start
.global USABLE_MEMORY_SIZE
USABLE_MEMORY_SIZE: .quad _usable_memory_size
.section .rodata
.global TEXT_START
.global TEXT_END
.global RODATA_START
.global RODATA_END
.global DATA_START
.global DATA_END
.global SDATA_START
.global SDATA_END
.global BSS_START
.global BSS_END
.global INITIAL_KERNEL_HEAP_START
.global INITIAL_KERNEL_HEAP_SIZE
.global USABLE_MEMORY_START
.global USABLE_MEMORY_SIZE
TEXT_START: .quad _text_start
TEXT_END: .quad _text_end
RODATA_START: .quad _rodata_start
RODATA_END: .quad _rodata_end
DATA_START: .quad _data_start
DATA_END: .quad _data_end
SDATA_START: .quad _sdata_start
SDATA_END: .quad _sdata_end
BSS_START: .quad _bss_start
BSS_END: .quad _bss_end
INITIAL_KERNEL_HEAP_START: .quad _initial_kernel_heap_start
INITIAL_KERNEL_HEAP_SIZE: .quad _initial_kernel_heap_size
USABLE_MEMORY_START: .quad _usable_memory_start
USABLE_MEMORY_SIZE: .quad _usable_memory_size

183
kernel/src/arch/riscv64/mod.rs
View file

@ -1,93 +1,90 @@
mod memory;
use core::{arch::{asm, global_asm}, fmt::Write};
use alloc::boxed::Box;
use sbi::system_reset::{ResetType, ResetReason, system_reset};
use spin::{Mutex, Once};
use uart_16550::MmioSerialPort;
use crate::{allocator, memory::PhysicalAddress, arch::riscv64::memory::{PAGE_TABLE, PageEntryFlags, PageSize, PageTable}};
global_asm!(include_str!("entry.s"));
global_asm!(include_str!("memory_regions.s"));
pub const PAGE_SIZE: usize = 4096;
extern {
static TEXT_START: PhysicalAddress;
static TEXT_END: PhysicalAddress;
static RODATA_START: PhysicalAddress;
static RODATA_END: PhysicalAddress;
static DATA_START: PhysicalAddress;
static DATA_END: PhysicalAddress;
static SDATA_START: PhysicalAddress;
static SDATA_END: PhysicalAddress;
static BSS_START: PhysicalAddress;
static BSS_END: PhysicalAddress;
static INITIAL_KERNEL_HEAP_START: PhysicalAddress;
static INITIAL_KERNEL_HEAP_SIZE: usize;
static USABLE_MEMORY_START: PhysicalAddress;
static USABLE_MEMORY_SIZE: usize;
}
static SERIAL_CONSOLE: Once<Mutex<MmioSerialPort>> = Once::new();
#[no_mangle]
unsafe extern fn _kernel_start() -> ! {
SERIAL_CONSOLE.call_once(|| Mutex::new(unsafe { MmioSerialPort::new(0x1000_0000) }));
crate::logger::init().expect("failed to set logger");
log::info!("Initialising AKern {}", crate::VERSION);
allocator::init(INITIAL_KERNEL_HEAP_START.as_mut_ptr::<u8>(), INITIAL_KERNEL_HEAP_SIZE);
memory::init(USABLE_MEMORY_START.into(), USABLE_MEMORY_SIZE / PAGE_SIZE);
let mut page_table_addr = PAGE_TABLE.get().unwrap().lock();
let mut page_table = page_table_addr.as_mut_ptr::<PageTable>().as_mut().unwrap();
// Map text (executable) section
page_table.identity_map_range(TEXT_START, TEXT_END, PageEntryFlags::ReadExecute);
// Map rodata section
page_table.identity_map_range(RODATA_START, RODATA_END, PageEntryFlags::Read);
// Map data section
page_table.identity_map_range(DATA_START, DATA_END, PageEntryFlags::ReadWrite);
// Map sdata section
page_table.identity_map_range(SDATA_START, SDATA_END, PageEntryFlags::ReadWrite);
// Map bss section (includes stack and initial kernel heap)
page_table.identity_map_range(BSS_START, BSS_END, PageEntryFlags::ReadWrite);
// Map usable memory range (as rw so not executable)
page_table.identity_map_range(USABLE_MEMORY_START, USABLE_MEMORY_START + USABLE_MEMORY_SIZE.into(), PageEntryFlags::ReadWrite);
// Map Uart so we can continue using serial
page_table.identity_map(0x1000_0000_usize.into(), PageEntryFlags::ReadWrite, PageSize::Size4KiB);
let table_ppn = page_table_addr.as_addr() as usize >> 12;
let satp_value = 8 << 60 | table_ppn;
log::info!("Enabling the MMU...");
asm!(
"csrw satp, {}",
"sfence.vma",
in(reg) satp_value,
);
log::info!("We're in PAGING LAND!");
#[allow(unreachable_code)]
match system_reset(ResetType::Shutdown, ResetReason::NoReason).unwrap() {}
}
/// Spin loop
pub fn sloop() -> ! {
loop {
unsafe { asm!("wfi") }
}
}
pub fn log(args: core::fmt::Arguments<'_>) -> core::fmt::Result {
SERIAL_CONSOLE.get().unwrap().lock().write_fmt(args)
}
mod memory;
use core::{arch::{asm, global_asm}, fmt::Write};
use alloc::boxed::Box;
use sbi::system_reset::{ResetType, ResetReason, system_reset};
use spin::{Mutex, Once};
use uart_16550::MmioSerialPort;
use crate::{allocator, memory::PhysicalAddress, arch::riscv64::memory::{PAGE_TABLE, PageEntryFlags, PageSize, PageTable}};
global_asm!(include_str!("entry.s"));
global_asm!(include_str!("memory_regions.s"));
pub const PAGE_SIZE: usize = 4096;
extern {
static TEXT_START: PhysicalAddress;
static TEXT_END: PhysicalAddress;
static RODATA_START: PhysicalAddress;
static RODATA_END: PhysicalAddress;
static DATA_START: PhysicalAddress;
static DATA_END: PhysicalAddress;
static SDATA_START: PhysicalAddress;
static SDATA_END: PhysicalAddress;
static BSS_START: PhysicalAddress;
static BSS_END: PhysicalAddress;
static INITIAL_KERNEL_HEAP_START: PhysicalAddress;
static INITIAL_KERNEL_HEAP_SIZE: usize;
static USABLE_MEMORY_START: PhysicalAddress;
static USABLE_MEMORY_SIZE: usize;
}
static SERIAL_CONSOLE: Once<Mutex<MmioSerialPort>> = Once::new();
#[no_mangle]
unsafe extern fn _kernel_start() -> ! {
SERIAL_CONSOLE.call_once(|| Mutex::new(unsafe { MmioSerialPort::new(0x1000_0000) }));
crate::logger::init().expect("failed to set logger");
log::info!("Initialising AKern {}", crate::VERSION);
allocator::init(INITIAL_KERNEL_HEAP_START.as_mut_ptr::<u8>(), INITIAL_KERNEL_HEAP_SIZE);
memory::init(USABLE_MEMORY_START.into(), USABLE_MEMORY_SIZE / PAGE_SIZE);
let mut page_table_addr = PAGE_TABLE.get().unwrap().lock();
let mut page_table = page_table_addr.as_mut_ptr::<PageTable>().as_mut().unwrap();
// Map text (executable) section
page_table.identity_map_range(TEXT_START, TEXT_END, PageEntryFlags::ReadExecute);
// Map rodata section
page_table.identity_map_range(RODATA_START, RODATA_END, PageEntryFlags::Read);
// Map data section
page_table.identity_map_range(DATA_START, DATA_END, PageEntryFlags::ReadWrite);
// Map sdata section
page_table.identity_map_range(SDATA_START, SDATA_END, PageEntryFlags::ReadWrite);
// Map bss section (includes stack and initial kernel heap)
page_table.identity_map_range(BSS_START, BSS_END, PageEntryFlags::ReadWrite);
// Map usable memory range (as rw so not executable)
page_table.identity_map_range(USABLE_MEMORY_START, USABLE_MEMORY_START + USABLE_MEMORY_SIZE.into(), PageEntryFlags::ReadWrite);
// Map Uart so we can continue using serial
page_table.identity_map(0x1000_0000_usize.into(), PageEntryFlags::ReadWrite, PageSize::Size4KiB);
let table_ppn = page_table_addr.as_addr() as usize >> 12;
let satp_value = 8 << 60 | table_ppn;
log::info!("Enabling MMU");
asm!(
"csrw satp, {}",
"sfence.vma",
in(reg) satp_value,
);
crate::kmain::kmain("baka=9", None);
}
/// Spin loop
pub fn sloop() -> ! {
loop {
unsafe { asm!("wfi") }
}
}
pub fn log(args: core::fmt::Arguments<'_>) -> core::fmt::Result {
SERIAL_CONSOLE.get().unwrap().lock().write_fmt(args)
}