mm: add stack based PMA

use 8MiB reserved array to manage up to 4GiB of physical memory
(4K Pages only)

Signed-off-by: Tianhao Wang <shrik3@mailbox.org>

1 files changed, 50 insertions, 1 deletions

diff --git a/src/mm/mod.rs b/src/mm/mod.rs
index b030dfb..27737e8 100644
--- a/src/mm/mod.rs
+++ b/src/mm/mod.rs
@@ -1,2 +1,51 @@
-pub mod heap_allocator;
+use crate::defs::*;
+use crate::io::*;
+use crate::machine::multiboot;
 pub mod pma;
+
+use lazy_static::lazy_static;
+use spin::Mutex;
+lazy_static! {
+	pub static ref GLOBAL_PMA: Mutex<pma::PageStackAllocator> =
+		Mutex::new(pma::PageStackAllocator::new());
+}
+
+pub fn init() {
+	let mbi = multiboot::get_mb_info().unwrap();
+	let mmapinfo = unsafe { mbi.get_mmap() }.unwrap();
+	let buf_start = mmapinfo.mmap_addr;
+	let buf_len = mmapinfo.mmap_length;
+	let buf_end = buf_start + buf_len;
+	let mut curr = buf_start as u64;
+	let mut inserted = 0;
+	loop {
+		if curr >= buf_end as u64 {
+			break;
+		}
+		let mblock = unsafe { &*(curr as *const multiboot::MultibootMmap) };
+		curr += mblock.size as u64;
+		curr += 4;
+		if mblock.mtype != multiboot::MultibootMmap::MTYPE_RAM {
+			continue;
+		}
+		if mblock.get_end() <= pmap_kernel_start() {
+			continue;
+		}
+		// TODO early break if the array is already full
+		if mblock.get_range().contains(pmap_kernel_end()) {
+			let r = Range {
+				addr: pmap_kernel_end(),
+				len: mblock.get_end() - pmap_kernel_end(),
+			};
+			inserted += GLOBAL_PMA.lock().insert_range(r);
+		} else {
+			inserted += GLOBAL_PMA.lock().insert_range(mblock.get_range());
+		}
+		println!(
+			"pma init: {:#X}KiB free memory, {:#X} pages inserted from block {:#X?}",
+			inserted * 0x4,
+			inserted,
+			mblock,
+		);
+	}
+}