support reloc type 28 and allow turntbl to exit

ddi/src/arch/riscv32/mod.rs

@@ -76,6 +76,19 @@ fn patch_lo12_iins(mut instruction: u32, pointer: u32) -> u32 {
     instruction
 }
 
+fn patch_lo12_sins(mut instruction: u32, pointer: u32) -> u32 {
+    // bits 0..5 are shifted seven left
+    // bits 5..12 are shifted 25 left
+    const MASK_1: u32 = 0x1F;
+    const TARGET_1: u32 = 0xF80;
+    const MASK_2: u32 = 0xFE0;
+    const TARGET_2: u32 = 0xFE000000;
+    let lo_1 = ((pointer & MASK_1) << 7) & TARGET_1;
+    let lo_2 = ((pointer & MASK_2) << 20) & TARGET_2;
+    instruction = (instruction & !(TARGET_1 | TARGET_2)) | lo_1 | lo_2;
+    instruction
+}
+
 fn sap_addr(target_pointer: u32, target_segment_base: u32, relocation_pointer: u32, current_segment_base: u32) -> u32 {
     (target_pointer).wrapping_sub(relocation_pointer)
 }
@@ -102,6 +115,13 @@ pub fn apply_relocation(segment_buffer: &mut [u8], current_segment_base: u32, ta
             i_ins = patch_lo12_iins(i_ins, addr);
             segment_buffer[i_ins_ptr..i_ins_ptr+4].copy_from_slice(&i_ins.to_le_bytes());
         }
+        x if x == RiscVRelocationType::Lo12S as u16 => {
+            let mut s_ins_ptr = relocation_header.relocation_pointer as usize;
+            let mut s_ins = u32::from_le_bytes(segment_buffer[s_ins_ptr..s_ins_ptr+4].try_into().unwrap());
+            let addr = relocation_header.target_pointer as u32 + target_segment_base;
+            s_ins = patch_lo12_sins(s_ins, addr);
+            segment_buffer[s_ins_ptr..s_ins_ptr+4].copy_from_slice(&s_ins.to_le_bytes());
+        }
         x => {
             unhandled_callback(x);
         }

turntable/src/main.rs

@@ -1,10 +1,11 @@
 #![no_std]
 #![no_main]
 
+use core::sync::atomic::{AtomicBool, Ordering};
 use crate::terminal::{print, println};
 use liblbos::fs::{DirectoryReader, FileSystem};
 
-static TEST: &[u8] = b"test";
+static NO_EXIT: AtomicBool = AtomicBool::new(false);
 
 #[panic_handler]
 fn panic(info: &core::panic::PanicInfo) -> ! {
@@ -131,6 +132,13 @@ fn execute(cmd: &str) {
             "ls" => {
                 lsdir();
             }
+            "exit" => {
+                if NO_EXIT.load(Ordering::Relaxed) {
+                    println("cannot exit as task 1");
+                } else {
+                    liblbos::syscalls::exit();
+                }
+            }
             _ => {
                 attempt_run_file(cmd);
             }
@@ -157,6 +165,9 @@ mod terminal;
 
 #[unsafe(no_mangle)]
 extern "C" fn main() {
+    let tid = liblbos::syscalls::current_task();
+    NO_EXIT.store(tid == 1, Ordering::Relaxed);
+
     print("\n\n");
     print("turntable v");
     const VERSION: &str = env!("CARGO_PKG_VERSION");