feat: move boot page table into board

kernel/src/arch/riscv/board/default/boot.rs

@@ -0,0 +1,41 @@
+use cfg_if::cfg_if;
+use core::arch::global_asm;
+
+cfg_if! {
+    if #[cfg(target_arch = "riscv32")] {
+        global_asm!("
+            .section .text
+                boot_setup_early_paging:
+                    jr ra
+            "
+        );
+    } else if #[cfg(target_arch = "riscv64")]{
+        global_asm!("
+            .section .text
+                boot_setup_early_paging:
+                    lla  t1, boot_page_table
+                    srli t1, t1, 12
+                    li   t2, 8 << 60
+                    or   t1, t1, t2
+                    csrw satp, t1
+                    sfence.vma
+                    jr ra
+        
+            .section .temp.boot_page_table
+                .align 12
+                boot_page_table:
+                    # sv39 page table
+                    # 0x00000000_00000000 -> 0x00000000 [ 0x00000000_00000000 -> 0x00000000_40000000 ]
+                    # 0x00000000_40000000 -> 0x40000000 [ 0x00000000_40000000 -> 0x00000000_80000000 ]
+                    # 0x00000000_80000000 -> 0x80000000 [ 0x00000000_80000000 -> 0x00000001_00000000 ]
+                    # 0xFFFFFFD0_00000000 -> 0x80000000 [ 0xFFFFFFD0_00000000 -> 0xFFFFFFD0_40000000 ]
+                    .quad (0x00000 << 10) | 0xf
+                    .quad (0x40000 << 10) | 0xf
+                    .quad (0x80000 << 10) | 0xf
+                    .zero 8 * 317
+                    .quad (0x80000 << 10) | 0xf
+                    .zero 8 * 191
+            "
+        );
+    }
+}

kernel/src/arch/riscv/board/default/mod.rs

@@ -1,4 +1,5 @@
 pub const TIMER_TICKS: u64 = 100_000; // 100ms
 
+mod boot;
 pub mod console;
 mod lowlevel;

kernel/src/arch/riscv/board/virt/mod.rs

@@ -5,5 +5,7 @@ pub const UART0_BASE: usize = 0x1000_0000;
 pub const UART0_LSR: usize = 0x1000_0005;
 pub const TEST_DEVICE: *mut u32 = 0x10_0000 as *mut u32;
 
+#[path = "../default/boot.rs"]
+mod boot;
 pub mod console;
 mod lowlevel;