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, 51 insertions, 8 deletions

diff --git a/src/defs.rs b/src/defs.rs
index cec17c9..3724c41 100644
--- a/src/defs.rs
+++ b/src/defs.rs
@@ -1,16 +1,59 @@
+// exported symbols from asm/linker.
+// They are always unsafe.
+extern "C" {
+	fn ___KERNEL_START__();
+	fn ___KERNEL_END__();
+	fn ___BSS_START__();
+	fn ___BSS_END__();
+}
+
+pub fn pmap_kernel_start() -> u64 {
+	return ___KERNEL_START__ as u64;
+}
+
+pub fn pmap_kernel_end() -> u64 {
+	return ___KERNEL_END__ as u64;
+}
+pub fn pmap_bss_start() -> u64 {
+	return ___BSS_START__ as u64;
+}
+
+pub fn pmap_bss_end() -> u64 {
+	return ___BSS_END__ as u64;
+}
+
 pub struct Mem;
 pub struct VAddr(u64);
+#[derive(Debug)]
+pub struct Range {
+	pub addr: u64,
+	pub len: u64,
+}
+
+pub fn roundup_4k(addr: u64) -> u64 {
+	return (addr + 0x1000) & 0xffff_ffff_ffff_0000;
+}
+
+pub fn rounddown_4k(addr: u64) -> u64 {
+	return addr & 0xffff_ffff_ffff_0000;
+}
+
+impl Range {
+	pub fn contains(&self, addr: u64) -> bool {
+		return self.addr <= addr && addr < self.addr + self.len;
+	}
+}
 
 impl Mem {
 	// units
-	pub const K: usize = 1024;
-	pub const M: usize = 1024 * Mem::K;
-	pub const G: usize = 1024 * Mem::M;
+	pub const K: u64 = 1024;
+	pub const M: u64 = 1024 * Mem::K;
+	pub const G: u64 = 1024 * Mem::M;
 	// physical memory layout: qemu defaults to 128 MiB phy Memory
-	pub const PHY_TOP: usize = 128 * Mem::M;
+	pub const PHY_TOP: u64 = 128 * Mem::M;
 	// 4 lv 4K paging
-	pub const PAGE_SIZE: usize = 0x1000;
-	pub const PAGE_SHIFT: usize = 12;
+	pub const PAGE_SIZE: u64 = 0x1000;
+	pub const PAGE_SHIFT: u64 = 12;
 	pub const PAGE_MASK: u64 = 0xfff;
 	pub const L0_SHIFT: u8 = 39;
 	pub const L0_MASK: u64 = 0x1ff << Mem::L0_SHIFT;
@@ -20,11 +63,11 @@ impl Mem {
 	pub const L2_MASK: u64 = 0x1ff << Mem::L2_SHIFT;
 	pub const L3_SHIFT: u8 = 12;
 	pub const L3_MASK: u64 = 0x1ff << Mem::L3_SHIFT;
-	pub const PHY_PAGES: usize = Mem::PHY_TOP >> Mem::PAGE_SHIFT;
+	pub const PHY_PAGES: u64 = Mem::PHY_TOP >> Mem::PAGE_SHIFT;
 	// size of frame allocator bitmap: number of physical frames / 8 for 128M
 	// memory (37268) 4k pages, 37268 bits are needed, hence
 	// 4096 bytes, exactly one page!
-	pub const PHY_BM_SIZE: usize = Mem::PHY_PAGES >> 3;
+	pub const PHY_BM_SIZE: u64 = Mem::PHY_PAGES >> 3;
 }
 
 impl VAddr {