From 96cfda564c03501625bd7b3a5a17bf80be91567d Mon Sep 17 00:00:00 2001
From: Garen Tyler <garentyler@garen.dev>
Date: Fri, 20 Oct 2023 16:29:26 -0600
Subject: [PATCH] make a spinmutex (and other things)

---
 Makefile                                      |   1 -
 kernel/console.c                              |  87 --------
 kernel/proc.h                                 |   4 +-
 kernel/rustkernel/src/buf.rs                  |   2 +-
 kernel/rustkernel/src/console.rs              | 211 ++++++++----------
 kernel/rustkernel/src/kalloc.rs               |   2 +-
 kernel/rustkernel/src/lib.rs                  |  12 +-
 kernel/rustkernel/src/printf.rs               |   4 +-
 kernel/rustkernel/src/proc.rs                 |  81 +++++--
 kernel/rustkernel/src/sync/mod.rs             |   3 +
 kernel/rustkernel/src/{ => sync}/sleeplock.rs |   2 +-
 kernel/rustkernel/src/{ => sync}/spinlock.rs  |  18 +-
 kernel/rustkernel/src/sync/spinmutex.rs       |  45 ++++
 kernel/rustkernel/src/trap.rs                 |  42 +++-
 kernel/rustkernel/src/uart.rs                 | 201 +++++++++++------
 15 files changed, 401 insertions(+), 314 deletions(-)
 delete mode 100644 kernel/console.c
 create mode 100644 kernel/rustkernel/src/sync/mod.rs
 rename kernel/rustkernel/src/{ => sync}/sleeplock.rs (96%)
 rename kernel/rustkernel/src/{ => sync}/spinlock.rs (84%)
 create mode 100644 kernel/rustkernel/src/sync/spinmutex.rs

diff --git a/Makefile b/Makefile
index 3724d41..fa22aa4 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,6 @@ P=programs
 
 OBJS = \
   $K/entry.o \
-  $K/console.o \
   $K/vm.o \
   $K/proc.o \
   $K/swtch.o \
diff --git a/kernel/console.c b/kernel/console.c
deleted file mode 100644
index 8e185d5..0000000
--- a/kernel/console.c
+++ /dev/null
@@ -1,87 +0,0 @@
-//
-// Console input and output, to the uart.
-// Reads are line at a time.
-// Implements special input characters:
-//   newline -- end of line
-//   control-h -- backspace
-//   control-u -- kill line
-//   control-d -- end of file
-//   control-p -- print process list
-//
-
-#include <stdarg.h>
-
-#include "types.h"
-#include "param.h"
-#include "spinlock.h"
-#include "sleeplock.h"
-#include "fs.h"
-#include "file.h"
-#include "memlayout.h"
-#include "riscv.h"
-#include "defs.h"
-#include "proc.h"
-
-#define BACKSPACE 0x100
-#define INPUT_BUF_SIZE 128
-#define C(x)  ((x)-'@')  // Control-x
-
-struct console {
-  struct spinlock lock;
-  
-  // input
-  char buf[INPUT_BUF_SIZE];
-  uint r;  // Read index
-  uint w;  // Write index
-  uint e;  // Edit index
-};
-
-extern struct console cons;
-void consputc(int c);
-int consolewrite(int user_src, uint64 src, int n);
-int consoleread(int user_dst, uint64 dst, int n);
-
-void consoleintr(int c)
-{
-  acquire(&cons.lock);
-
-  switch(c){
-  case C('P'):  // Print process list.
-    procdump();
-    break;
-  case C('U'):  // Kill line.
-    while(cons.e != cons.w &&
-          cons.buf[(cons.e-1) % INPUT_BUF_SIZE] != '\n'){
-      cons.e--;
-      consputc(BACKSPACE);
-    }
-    break;
-  case C('H'): // Backspace
-  case '\x7f': // Delete key
-    if(cons.e != cons.w){
-      cons.e--;
-      consputc(BACKSPACE);
-    }
-    break;
-  default:
-    if(c != 0 && cons.e-cons.r < INPUT_BUF_SIZE){
-      c = (c == '\r') ? '\n' : c;
-
-      // echo back to the user.
-      consputc(c);
-
-      // store for consumption by consoleread().
-      cons.buf[cons.e++ % INPUT_BUF_SIZE] = c;
-
-      if(c == '\n' || c == C('D') || cons.e-cons.r == INPUT_BUF_SIZE){
-        // wake up consoleread() if a whole line (or end-of-file)
-        // has arrived.
-        cons.w = cons.e;
-        wakeup(&cons.r);
-      }
-    }
-    break;
-  }
-  
-  release(&cons.lock);
-}
diff --git a/kernel/proc.h b/kernel/proc.h
index 03fe4e1..46c59df 100644
--- a/kernel/proc.h
+++ b/kernel/proc.h
@@ -22,8 +22,8 @@ struct context {
 struct cpu {
   struct proc *proc;          // The process running on this cpu, or null.
   struct context context;     // swtch() here to enter scheduler().
-  int noff;                   // Depth of push_off() nesting.
-  int intena;                 // Were interrupts enabled before push_off()?
+  int interrupt_disable_layers;    // Depth of push_off() nesting.
+  int previous_interrupts_enabled; // Were interrupts enabled before push_off()?
 };
 
 extern struct cpu cpus[NCPU];
diff --git a/kernel/rustkernel/src/buf.rs b/kernel/rustkernel/src/buf.rs
index 05e38e4..ba07a49 100644
--- a/kernel/rustkernel/src/buf.rs
+++ b/kernel/rustkernel/src/buf.rs
@@ -1,4 +1,4 @@
-use crate::{fs::BSIZE, sleeplock::Sleeplock};
+use crate::{fs::BSIZE, sync::sleeplock::Sleeplock};
 
 #[repr(C)]
 pub struct Buf {
diff --git a/kernel/rustkernel/src/console.rs b/kernel/rustkernel/src/console.rs
index 48cba15..1ae61a0 100644
--- a/kernel/rustkernel/src/console.rs
+++ b/kernel/rustkernel/src/console.rs
@@ -10,66 +10,73 @@
 
 use crate::{
     file::{devsw, CONSOLE},
-    proc::{killed, myproc, sleep},
-    spinlock::{initlock, Spinlock},
+    proc::{killed, myproc, sleep_mutex, wakeup, procdump},
+    sync::spinmutex::SpinMutex,
     uart::{uartinit, uartputc, uartputc_sync},
 };
 use core::{
-    ffi::{c_void, CStr},
+    ffi::c_void,
     ptr::addr_of_mut,
 };
 
 extern "C" {
     fn either_copyin(dst: *mut c_void, user_src: i32, src: u64, len: u64) -> i32;
     fn either_copyout(user_dst: i32, dst: u64, src: *mut c_void, len: u64) -> i32;
-
-    pub fn consoleintr(c: i32);
-    fn wakeup(chan: *mut c_void);
-    fn procdump();
 }
 
-pub const BACKSPACE: i32 = 0x100;
-pub const INPUT_BUF_SIZE: u64 = 128;
+pub const BACKSPACE: u8 = 0x00;
+pub const INPUT_BUF_SIZE: usize = 128;
+
+pub struct Console {
+    pub buffer: [u8; INPUT_BUF_SIZE],
+    pub read_index: usize,
+    pub write_index: usize,
+    pub edit_index: usize,
+}
+impl Console {
+    pub fn read_byte(&self) -> &u8 {
+        &self.buffer[self.read_index % self.buffer.len()]
+    }
+    pub fn write_byte(&mut self) -> &mut u8 {
+        let i = self.write_index % self.buffer.len();
+        &mut self.buffer[i]
+    }
+    pub fn edit_byte(&mut self) -> &mut u8 {
+        let i = self.edit_index % self.buffer.len();
+        &mut self.buffer[i]
+    }
+}
 
 #[no_mangle]
-pub static mut cons: Console = Console {
-    lock: unsafe { Spinlock::uninitialized() },
-    buffer: [0u8; INPUT_BUF_SIZE as usize],
+pub static cons: SpinMutex<Console> = SpinMutex::new(Console {
+    buffer: [0u8; INPUT_BUF_SIZE],
     read_index: 0,
     write_index: 0,
     edit_index: 0,
-};
+});
 
 /// ctrl-x
-fn ctrl_x(x: char) -> char {
-    ((x as u8) - b'@') as char
+const fn ctrl_x(x: u8) -> u8 {
+    x - b'@'
 }
 
 /// Send one character to the UART.
 ///
 /// Called by printf(), and to echo input
 /// characters but not from write().
-#[no_mangle]
-pub unsafe extern "C" fn consputc(c: i32) {
-    if c == BACKSPACE {
-        // If the user typed backspace, overwrite with a space.
-        uartputc_sync('\x08' as i32);
-        uartputc_sync(' ' as i32);
-        uartputc_sync('\x08' as i32);
-    } else {
-        uartputc_sync(c);
+pub fn consputc(c: u8) {
+    unsafe {
+        if c == BACKSPACE {
+            // If the user typed backspace, overwrite with a space.
+            uartputc_sync(0x08);
+            uartputc_sync(b' ');
+            uartputc_sync(0x08);
+        } else {
+            uartputc_sync(c);
+        }
     }
 }
 
-#[repr(C)]
-pub struct Console {
-    pub lock: Spinlock,
-    pub buffer: [u8; INPUT_BUF_SIZE as usize],
-    pub read_index: u32,
-    pub write_index: u32,
-    pub edit_index: u32,
-}
-
 /// User write()s to the console go here.
 #[no_mangle]
 pub unsafe extern "C" fn consolewrite(user_src: i32, src: u64, n: i32) -> i32 {
@@ -79,7 +86,7 @@ pub unsafe extern "C" fn consolewrite(user_src: i32, src: u64, n: i32) -> i32 {
         if either_copyin(addr_of_mut!(c).cast(), user_src, src + i as u64, 1) == -1 {
             return i;
         } else {
-            uartputc(c as i32);
+            uartputc(c as u8);
         }
     }
     0
@@ -96,31 +103,32 @@ pub unsafe extern "C" fn consoleread(user_dst: i32, mut dst: u64, mut n: i32) ->
     let mut c;
     let mut cbuf;
 
-    cons.lock.lock();
+    // cons.lock.lock();
+    let mut console = cons.lock();
 
     while n > 0 {
         // Wait until interrupt handler has put
         // some input into cons.buffer.
-        while cons.read_index == cons.write_index {
+        while console.read_index == console.write_index {
             if killed(myproc()) != 0 {
-                cons.lock.unlock();
+                // cons.lock.unlock();
                 return -1;
             }
-            sleep(
-                addr_of_mut!(cons.read_index).cast(),
-                addr_of_mut!(cons.lock),
+            sleep_mutex(
+                addr_of_mut!(console.read_index).cast(),
+                &mut console,
             );
         }
-
-        c = cons.buffer[(cons.read_index % INPUT_BUF_SIZE as u32) as usize];
-        cons.read_index += 1;
+        
+        c = *console.read_byte();
+        console.read_index += 1;
 
         // ctrl-D or EOF
-        if c == ctrl_x('D') as u8 {
+        if c == ctrl_x(b'D') {
             if n < target {
                 // Save ctrl-D for next time, to make
                 // sure caller gets a 0-byte result.
-                cons.read_index -= 1;
+                console.read_index -= 1;
             }
             break;
         }
@@ -141,81 +149,12 @@ pub unsafe extern "C" fn consoleread(user_dst: i32, mut dst: u64, mut n: i32) ->
         }
     }
 
-    cons.lock.unlock();
+    // cons.lock.unlock();
 
     target - n
 }
 
-// /// The console input interrupt handler.
-// ///
-// /// uartintr() calls this for input character.
-// /// Do erase/kill processing, then append to cons.buf.
-// /// Wake up consoleread() if a whole line has arrived.
-// #[no_mangle]
-// pub unsafe extern "C" fn consoleintr(c: i32) {
-//     cons.lock.lock();
-//
-//     let ctrl_p = ctrl_x('P') as u8 as i8 as i32;
-//     let ctrl_u = ctrl_x('P') as u8 as i8 as i32;
-//     let ctrl_h = ctrl_x('P') as u8 as i8 as i32;
-//     let ctrl_d = ctrl_x('D') as u8 as i8 as i32;
-//     let cr = '\r' as u8 as i8 as i32;
-//     let nl = '\n' as u8 as i8 as i32;
-//
-//     match c {
-//         // Print process list.
-//         ctrl_p => procdump(),
-//         // Kill line
-//         ctrl_u => {
-//             while cons.edit_index != cons.write_index
-//                 && cons.buffer[((cons.edit_index - 1) % INPUT_BUF_SIZE as u32) as usize]
-//                     != '\n' as u8
-//             {
-//                 cons.edit_index -= 1;
-//                 consputc(BACKSPACE);
-//             }
-//         }
-//         // Backspace
-//         ctrl_h => {
-//             if cons.edit_index != cons.write_index {
-//                 cons.edit_index -= 1;
-//                 consputc(BACKSPACE);
-//             }
-//         }
-//         c => {
-//             if cons.edit_index - cons.read_index < INPUT_BUF_SIZE as u32 {
-//                 let c = if c == cr { nl } else { c };
-//
-//                 // Echo back to the user.
-//                 consputc(c);
-//
-//                 // Store for consumption by consoleread().
-//                 cons.buffer[(cons.edit_index % INPUT_BUF_SIZE as u32) as usize] = c as i8 as u8;
-//                 cons.edit_index += 1;
-//
-//                 if c == nl
-//                     || c == ctrl_d
-//                     || cons.edit_index - cons.read_index == INPUT_BUF_SIZE as u32
-//                 {
-//                     // Wake up consoleread() if a whole line (or EOF) has arrived.
-//                     cons.write_index = cons.edit_index;
-//                     wakeup(addr_of_mut!(cons.read_index).cast());
-//                 }
-//             }
-//         }
-//     }
-//
-//     cons.lock.unlock();
-// }
-
 pub unsafe fn consoleinit() {
-    initlock(
-        addr_of_mut!(cons.lock),
-        CStr::from_bytes_with_nul(b"cons\0")
-            .unwrap()
-            .as_ptr()
-            .cast_mut(),
-    );
     uartinit();
 
     // Connect read and write syscalls
@@ -223,3 +162,45 @@ pub unsafe fn consoleinit() {
     devsw[CONSOLE].read = consoleread as usize as *const i32;
     devsw[CONSOLE].write = consolewrite as usize as *const i32;
 }
+
+/// The console input interrupt handler.
+///
+/// uartintr() calls this for input character.
+/// Do erase/kill processing, then append to cons.buf.
+/// Wake up consoleread() if a whole line has arrived.
+pub fn consoleintr(mut c: u8) {
+    // cons.lock.lock();
+    let mut console = cons.lock();
+
+    if c == ctrl_x(b'P') {
+        // Print process list.
+        unsafe { procdump() };
+    } else if c == ctrl_x(b'U') {
+        // Kill line.
+        while console.edit_index != console.write_index && console.buffer[(console.edit_index - 1) % INPUT_BUF_SIZE] != b'\n' {
+            console.edit_index -= 1;
+            consputc(BACKSPACE);
+        }
+    } else if c == ctrl_x(b'H') || c == 0x7f {
+        // Backspace or delete key.
+        if console.edit_index != console.write_index {
+            console.edit_index -= 1;
+            consputc(BACKSPACE);
+        }
+    } else if c != 0 && console.edit_index - console.read_index < INPUT_BUF_SIZE {
+        c = if c == b'\r' { b'\n' } else { c };
+
+        // Echo back to the user.
+        consputc(c);
+
+        // Store for consumption by consoleread().
+        *console.edit_byte() = c;
+        console.edit_index += 1;
+
+        if c == b'\n' || c == ctrl_x(b'D') || console.edit_index - console.read_index == INPUT_BUF_SIZE {
+            // Wake up consoleread() if a whole line (or EOF) has arrived.
+            console.write_index = console.edit_index;
+            unsafe { wakeup(addr_of_mut!(console.read_index).cast()) };
+        }
+    }
+}
diff --git a/kernel/rustkernel/src/kalloc.rs b/kernel/rustkernel/src/kalloc.rs
index 5efd7a4..1ce5892 100644
--- a/kernel/rustkernel/src/kalloc.rs
+++ b/kernel/rustkernel/src/kalloc.rs
@@ -4,7 +4,7 @@
 
 use crate::{
     riscv::{memlayout::PHYSTOP, pg_round_up, PGSIZE},
-    spinlock::Spinlock,
+    sync::spinlock::Spinlock,
     string::memset,
 };
 use core::{
diff --git a/kernel/rustkernel/src/lib.rs b/kernel/rustkernel/src/lib.rs
index cad269f..7d8b0ed 100644
--- a/kernel/rustkernel/src/lib.rs
+++ b/kernel/rustkernel/src/lib.rs
@@ -2,6 +2,7 @@
 #![no_std]
 #![allow(dead_code)]
 #![allow(clippy::missing_safety_doc)]
+#![feature(negative_impls)]
 
 extern crate alloc;
 extern crate core;
@@ -15,8 +16,7 @@ pub(crate) mod param;
 pub mod printf;
 pub mod proc;
 pub(crate) mod riscv;
-pub mod sleeplock;
-pub mod spinlock;
+pub mod sync;
 pub mod start;
 pub mod string;
 pub mod syscall;
@@ -35,7 +35,7 @@ extern "C" {
     pub fn fileinit();
     pub fn virtio_disk_init();
     pub fn userinit();
-    pub fn scheduler();
+    // pub fn scheduler();
 }
 
 use crate::{printf::print, proc::cpuid};
@@ -45,7 +45,7 @@ pub static mut STARTED: bool = false;
 pub static mut PANICKED: bool = false;
 
 #[no_mangle]
-pub unsafe extern "C" fn main() {
+pub unsafe extern "C" fn main() -> ! {
     if cpuid() == 0 {
         console::consoleinit();
         printf::printfinit();
@@ -73,7 +73,7 @@ pub unsafe extern "C" fn main() {
         riscv::plic::plicinithart();
     }
 
-    scheduler();
+    proc::scheduler();
 }
 
 #[panic_handler]
@@ -85,7 +85,7 @@ fn panic_wrapper(panic_info: &core::panic::PanicInfo) -> ! {
     }
 
     unsafe { crate::PANICKED = true };
-
+    
     loop {
         core::hint::spin_loop();
     }
diff --git a/kernel/rustkernel/src/printf.rs b/kernel/rustkernel/src/printf.rs
index b8ba0d2..1d2723c 100644
--- a/kernel/rustkernel/src/printf.rs
+++ b/kernel/rustkernel/src/printf.rs
@@ -1,4 +1,4 @@
-use crate::spinlock::Spinlock;
+use crate::sync::spinlock::Spinlock;
 use core::ffi::{c_char, CStr};
 
 pub use crate::panic;
@@ -25,7 +25,7 @@ macro_rules! print {
         ).unwrap();
 
         for c in s.as_bytes() {
-            unsafe { $crate::console::consputc(*c as i8 as i32) };
+            $crate::console::consputc(*c);
         }
 
         unsafe { $crate::kalloc::kfree(buf.cast()) };
diff --git a/kernel/rustkernel/src/proc.rs b/kernel/rustkernel/src/proc.rs
index d7dcb43..b5b5ca7 100644
--- a/kernel/rustkernel/src/proc.rs
+++ b/kernel/rustkernel/src/proc.rs
@@ -4,7 +4,8 @@ use crate::{
     kalloc::kfree,
     param::*,
     riscv::{self, Pagetable, PTE_W},
-    spinlock::{pop_off, push_off, Spinlock},
+    sync::spinlock::{pop_off, push_off, Spinlock},
+    sync::spinmutex::SpinMutexGuard,
 };
 use core::{
     ffi::{c_char, c_void},
@@ -29,20 +30,22 @@ extern "C" {
     pub fn fork() -> i32;
     pub fn exit(status: i32) -> !;
     pub fn wait(addr: u64) -> i32;
+    pub fn procdump();
     pub fn proc_pagetable(p: *mut Proc) -> Pagetable;
     pub fn proc_freepagetable(pagetable: Pagetable, sz: u64);
-    pub fn wakeup(chan: *mut c_void);
+    pub fn wakeup(chan: *const c_void);
     pub fn allocproc() -> *mut Proc;
     // pub fn freeproc(p: *mut Proc);
     pub fn uvmalloc(pagetable: Pagetable, oldsz: u64, newsz: u64, xperm: i32) -> u64;
     pub fn uvmdealloc(pagetable: Pagetable, oldsz: u64, newsz: u64) -> u64;
     // pub fn sched();
+    pub fn scheduler() -> !;
     pub fn swtch(a: *mut Context, b: *mut Context);
 }
 
 /// Saved registers for kernel context switches.
 #[repr(C)]
-#[derive(Default)]
+#[derive(Copy, Clone, Default)]
 pub struct Context {
     pub ra: u64,
     pub sp: u64,
@@ -61,26 +64,47 @@ pub struct Context {
     pub s10: u64,
     pub s11: u64,
 }
+impl Context {
+    pub const fn new() -> Context {
+        Context {
+            ra: 0u64,
+            sp: 0u64,
+            s0: 0u64,
+            s1: 0u64,
+            s2: 0u64,
+            s3: 0u64,
+            s4: 0u64,
+            s5: 0u64,
+            s6: 0u64,
+            s7: 0u64,
+            s8: 0u64,
+            s9: 0u64,
+            s10: 0u64,
+            s11: 0u64,
+        }
+    }
+}
 
 /// Per-CPU state.
 #[repr(C)]
+#[derive(Copy, Clone)]
 pub struct Cpu {
-    /// The process running on this cpu, or null.
     pub proc: *mut Proc,
-    /// swtch() here to enter scheduler()
+        /// swtch() here to enter scheduler()
     pub context: Context,
     /// Depth of push_off() nesting.
-    pub noff: i32,
+    pub interrupt_disable_layers: i32,
     /// Were interrupts enabled before push_off()?
-    pub intena: i32,
+    pub previous_interrupts_enabled: i32,
 }
-impl Default for Cpu {
-    fn default() -> Self {
+impl Cpu {
+    pub const fn new() -> Cpu {
         Cpu {
             proc: null_mut(),
-            context: Context::default(),
-            noff: 0,
-            intena: 0,
+            // proc: None,
+            context: Context::new(),
+            interrupt_disable_layers: 0,
+            previous_interrupts_enabled: 0,
         }
     }
 }
@@ -360,9 +384,9 @@ pub unsafe extern "C" fn r#yield() {
 
 /// Switch to scheduler.  Must hold only p->lock
 /// and have changed proc->state. Saves and restores
-/// intena because intena is a property of this
+/// previous_interrupts_enabled because previous_interrupts_enabled is a property of this
 /// kernel thread, not this CPU. It should
-/// be proc->intena and proc->noff, but that would
+/// be proc->previous_interrupts_enabled and proc->interrupt_disable_layers, but that would
 /// break in the few places where a lock is held but
 /// there's no process.
 #[no_mangle]
@@ -372,7 +396,7 @@ pub unsafe extern "C" fn sched() {
 
     if !(*p).lock.held_by_current_cpu() {
         panic!("sched p->lock");
-    } else if (*c).noff != 1 {
+    } else if (*c).interrupt_disable_layers != 1 {
         panic!("sched locks");
     } else if (*p).state == ProcState::Running {
         panic!("sched running");
@@ -380,9 +404,9 @@ pub unsafe extern "C" fn sched() {
         panic!("sched interruptible");
     }
 
-    let intena = (*c).intena;
+    let previous_interrupts_enabled = (*c).previous_interrupts_enabled;
     swtch(addr_of_mut!((*p).context), addr_of_mut!((*c).context));
-    (*c).intena = intena;
+    (*c).previous_interrupts_enabled = previous_interrupts_enabled;
 }
 
 /// Atomically release lock and sleep on chan.
@@ -415,6 +439,28 @@ pub unsafe extern "C" fn sleep(chan: *mut c_void, lock: *mut Spinlock) {
     (*lock).lock();
 }
 
+pub unsafe fn sleep_mutex<T>(chan: *mut c_void, mutex: &mut SpinMutexGuard<T>) {
+    let p = myproc();
+    let mutex = mutex.mutex;
+
+    (*p).lock.lock();
+    mutex.unlock();
+
+    // Go to sleep.
+    (*p).chan = chan;
+    (*p).state = ProcState::Sleeping;
+
+    sched();
+
+    // Tidy up.
+    (*p).chan = null_mut();
+
+    // Reacquire original lock.
+    (*p).lock.unlock();
+    let guard = mutex.lock();
+    core::mem::forget(guard);
+}
+
 /// Kill the process with the given pid.
 /// The victim won't exit until it tries to return
 /// to user space (see usertrap() in trap.c).
@@ -453,3 +499,4 @@ pub unsafe extern "C" fn killed(p: *mut Proc) -> i32 {
     (*p).lock.unlock();
     k
 }
+ 
\ No newline at end of file
diff --git a/kernel/rustkernel/src/sync/mod.rs b/kernel/rustkernel/src/sync/mod.rs
new file mode 100644
index 0000000..3d543ce
--- /dev/null
+++ b/kernel/rustkernel/src/sync/mod.rs
@@ -0,0 +1,3 @@
+pub mod sleeplock;
+pub mod spinlock;
+pub mod spinmutex;
diff --git a/kernel/rustkernel/src/sleeplock.rs b/kernel/rustkernel/src/sync/sleeplock.rs
similarity index 96%
rename from kernel/rustkernel/src/sleeplock.rs
rename to kernel/rustkernel/src/sync/sleeplock.rs
index 443e5a3..c58382e 100644
--- a/kernel/rustkernel/src/sleeplock.rs
+++ b/kernel/rustkernel/src/sync/sleeplock.rs
@@ -1,6 +1,6 @@
 use crate::{
     proc::{myproc, sleep, wakeup},
-    spinlock::{self, Spinlock},
+    sync::spinlock::{self, Spinlock},
 };
 use core::{ffi::c_char, ptr::addr_of_mut};
 
diff --git a/kernel/rustkernel/src/spinlock.rs b/kernel/rustkernel/src/sync/spinlock.rs
similarity index 84%
rename from kernel/rustkernel/src/spinlock.rs
rename to kernel/rustkernel/src/sync/spinlock.rs
index 4c676bf..63ffea4 100644
--- a/kernel/rustkernel/src/spinlock.rs
+++ b/kernel/rustkernel/src/sync/spinlock.rs
@@ -23,7 +23,7 @@ impl Spinlock {
         }
     }
     /// Initializes a `Spinlock`.
-    pub fn new(name: *mut c_char) -> Spinlock {
+    pub const fn new(name: *mut c_char) -> Spinlock {
         Spinlock {
             locked: AtomicBool::new(false),
             cpu: null_mut(),
@@ -57,7 +57,7 @@ impl Spinlock {
         }
 
         self.cpu = null_mut();
-
+        
         self.locked.store(false, Ordering::Release);
 
         pop_off();
@@ -94,24 +94,26 @@ pub unsafe extern "C" fn push_off() {
     let cpu = mycpu();
 
     riscv::intr_off();
-    if (*cpu).noff == 0 {
-        (*cpu).intena = old;
+    if (*cpu).interrupt_disable_layers == 0 {
+        (*cpu).previous_interrupts_enabled = old;
     }
-    (*cpu).noff += 1;
+    (*cpu).interrupt_disable_layers += 1;
 }
 #[no_mangle]
 pub unsafe extern "C" fn pop_off() {
     let cpu = mycpu();
 
     if riscv::intr_get() == 1 {
+        // crate::panic_byte(b'0');
         panic!("pop_off - interruptible");
-    } else if (*cpu).noff < 1 {
+    } else if (*cpu).interrupt_disable_layers < 1 {
+        // crate::panic_byte(b'1');
         panic!("pop_off");
     }
 
-    (*cpu).noff -= 1;
+    (*cpu).interrupt_disable_layers -= 1;
 
-    if (*cpu).noff == 0 && (*cpu).intena == 1 {
+    if (*cpu).interrupt_disable_layers == 0 && (*cpu).previous_interrupts_enabled == 1 {
         riscv::intr_on();
     }
 }
diff --git a/kernel/rustkernel/src/sync/spinmutex.rs b/kernel/rustkernel/src/sync/spinmutex.rs
new file mode 100644
index 0000000..ffd0f15
--- /dev/null
+++ b/kernel/rustkernel/src/sync/spinmutex.rs
@@ -0,0 +1,45 @@
+use core::{cell::UnsafeCell, ops::{Deref, DerefMut, Drop}, sync::atomic::{AtomicBool, Ordering}};
+
+pub struct SpinMutex<T> {
+    locked: AtomicBool,
+    pub inner: UnsafeCell<T>,
+}
+impl<T> SpinMutex<T> {
+    pub const fn new(value: T) -> SpinMutex<T> {
+        SpinMutex {
+            locked: AtomicBool::new(false),
+            inner: UnsafeCell::new(value),
+        }
+    }
+    pub fn lock(&self) -> SpinMutexGuard<'_, T> {
+        while self.locked.swap(true, Ordering::Acquire) {
+            core::hint::spin_loop();
+        }
+        SpinMutexGuard { mutex: &self }
+    }
+    pub unsafe fn unlock(&self) {
+        self.locked.store(false, Ordering::Release);
+    }
+}
+unsafe impl<T> Sync for SpinMutex<T> where T: Send {}
+
+pub struct SpinMutexGuard<'m, T> {
+    pub mutex: &'m SpinMutex<T>,
+}
+impl<'m, T> Deref for SpinMutexGuard<'m, T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        unsafe { & *self.mutex.inner.get() }
+    }
+}
+impl<'m, T> DerefMut for SpinMutexGuard<'m, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        unsafe { &mut *self.mutex.inner.get() }
+    }
+}
+impl<'m, T> Drop for SpinMutexGuard<'m, T> {
+    fn drop(&mut self) {
+        unsafe { self.mutex.unlock() }
+    }
+}
diff --git a/kernel/rustkernel/src/trap.rs b/kernel/rustkernel/src/trap.rs
index b217187..68d3f8e 100644
--- a/kernel/rustkernel/src/trap.rs
+++ b/kernel/rustkernel/src/trap.rs
@@ -1,8 +1,8 @@
 use crate::{
     printf::print,
-    proc::{cpuid, wakeup},
+    proc::{cpuid, wakeup, mycpu},
     riscv::*,
-    spinlock::Spinlock,
+    sync::spinlock::Spinlock,
 };
 use core::{ffi::CStr, ptr::addr_of_mut};
 
@@ -142,3 +142,41 @@ pub unsafe extern "C" fn devintr() -> i32 {
         0
     }
 }
+
+pub struct InterruptBlocker;
+impl InterruptBlocker {
+    pub fn new() {
+        unsafe {
+            let interrupts_before = intr_get();
+            let cpu = mycpu();
+            
+            intr_off();
+
+            if (*cpu).interrupt_disable_layers == 0 {
+                (*cpu).previous_interrupts_enabled = interrupts_before;
+            }
+            (*cpu).interrupt_disable_layers += 1;
+            // crate::sync::spinlock::push_off();
+        }
+    }
+}
+impl core::ops::Drop for InterruptBlocker {
+    fn drop(&mut self) {
+        unsafe {
+            let cpu = mycpu();
+
+            if intr_get() == 1 || (*cpu).interrupt_disable_layers < 1 {
+                // panic!("pop_off mismatched");
+                return;
+            }
+
+            (*cpu).interrupt_disable_layers -= 1;
+
+            if (*cpu).interrupt_disable_layers == 0 && (*cpu).previous_interrupts_enabled == 1 {
+                intr_on();
+            }
+            // crate::sync::spinlock::pop_off();
+        }
+    }
+}
+impl !Send for InterruptBlocker {}
diff --git a/kernel/rustkernel/src/uart.rs b/kernel/rustkernel/src/uart.rs
index 735dfd8..6a97f58 100644
--- a/kernel/rustkernel/src/uart.rs
+++ b/kernel/rustkernel/src/uart.rs
@@ -3,85 +3,143 @@
 
 use crate::{
     console::consoleintr,
-    proc::{sleep, wakeup},
+    proc::{sleep, sleep_mutex, wakeup},
     riscv::memlayout::UART0,
-    spinlock::{pop_off, push_off, Spinlock},
+    sync::spinlock::{pop_off, push_off, Spinlock},
+    sync::spinmutex::SpinMutex,
+    trap::InterruptBlocker,
 };
 use core::{ffi::CStr, ptr::addr_of_mut};
 
-/// The UART control registers are memory-mapped
-/// at address UART0. This function returns the
-/// address of one of the registers.
-#[inline(always)]
-fn get_register_addr<N: Into<u64>>(register: N) -> *mut u8 {
-    let register: u64 = register.into();
-    (UART0 + register) as *mut u8
+enum Register {
+    ReceiveHolding,
+    TransmitHolding,
+    InterruptEnable,
+    FIFOControl,
+    InterruptStatus,
+    LineControl,
+    LineStatus,
+}
+impl Register {
+    pub fn as_ptr(&self) -> *mut u8 {
+        let addr = UART0 + match self {
+            Register::ReceiveHolding => 0,
+            Register::TransmitHolding => 0,
+            Register::InterruptEnable => 1,
+            Register::FIFOControl => 2,
+            Register::InterruptStatus => 2,
+            Register::LineControl => 2,
+            Register::LineStatus => 5,
+        };
+        addr as *mut u8
+    }
+    pub fn read(&self) -> u8 {
+        unsafe { self.as_ptr().read_volatile() }
+    }
+    pub fn write(&self, value: u8) {
+        unsafe { self.as_ptr().write_volatile(value) }
+    }
+}
+
+pub static uart: SpinMutex<Uart> = SpinMutex::new(Uart {
+    buffer: [0u8; UART_TX_BUF_SIZE],
+    write_index: 0,
+    read_index: 0,
+});
+
+pub struct Uart {
+    pub buffer: [u8; UART_TX_BUF_SIZE],
+    pub write_index: usize,
+    pub read_index: usize,
+}
+impl Uart {
+    pub fn write_byte_sync(x: u8) {
+        // let _ = InterruptBlocker::new();
+        unsafe { push_off(); }
+
+        if unsafe { crate::PANICKED } {
+            loop {
+                core::hint::spin_loop();
+            }
+        }
+
+        // Wait for Transmit Holding Empty to be set in LSR.
+        while Register::LineStatus.read() & LSR_TX_IDLE == 0 {
+            core::hint::spin_loop();
+        }
+
+        Register::TransmitHolding.write(x);
+
+        unsafe { pop_off(); }
+    }
+    /// If the UART is idle, and a character is
+    /// waiting in the transmit buffer, send it.
+    pub fn send_queued_bytes(&mut self) {
+        loop {
+            self.write_index %= self.buffer.len();
+            self.read_index %= self.buffer.len();
+
+            if self.write_index == self.read_index {
+                // Transmit buffer is ready.
+                return;
+            }
+
+            let c = self.buffer[self.read_index];
+            self.read_index += 1;
+
+            // Maybe uartputc() is waiting for space in the buffer.
+            unsafe { wakeup(addr_of_mut!(self.read_index).cast()) };
+
+            Register::TransmitHolding.write(c);
+        }
+    }
 }
 
 // The UART control registers.
 // Some have different meanings for read vs write.
 // See http://byterunner.com/16550.html
 
-/// Receive Holding Register (for input bytes)
-const RHR: u8 = 0;
-/// Transmit Holding Register (for output bytes)
-const THR: u8 = 0;
 /// Interrupt Enable Register
-const IER: u8 = 1;
 const IER_RX_ENABLE: u8 = 1 << 0;
 const IER_TX_ENABLE: u8 = 1 << 1;
-/// FIFO control register
-const FCR: u8 = 2;
 const FCR_FIFO_ENABLE: u8 = 1 << 0;
 /// Clear the content of the two FIFOs.
 const FCR_FIFO_CLEAR: u8 = 3 << 1;
-/// Interrupt Status Register
-const ISR: u8 = 2;
-/// Line Control Register
-const LCR: u8 = 2;
 const LCR_EIGHT_BITS: u8 = 3;
 /// Special mode to set baud rate
 const LCR_BAUD_LATCH: u8 = 1 << 7;
-/// Line Status Register
-const LSR: u8 = 5;
 /// Input is waiting to be read from RHR
 const LSR_RX_READY: u8 = 1 << 0;
 /// THR can accept another character to send
 const LSR_TX_IDLE: u8 = 1 << 5;
 
-#[inline(always)]
-unsafe fn read_register<N: Into<u64>>(register: N) -> u8 {
-    *get_register_addr(register)
-}
-#[inline(always)]
-unsafe fn write_register<N: Into<u64>>(register: N, value: u8) {
-    *get_register_addr(register) = value;
-}
-
 static mut uart_tx_lock: Spinlock = unsafe { Spinlock::uninitialized() };
-const UART_TX_BUF_SIZE: u64 = 32;
-static mut uart_tx_buf: [u8; UART_TX_BUF_SIZE as usize] = [0u8; UART_TX_BUF_SIZE as usize];
+const UART_TX_BUF_SIZE: usize = 32;
+static mut uart_tx_buf: [u8; UART_TX_BUF_SIZE] = [0u8; UART_TX_BUF_SIZE];
+// static uart_tx_buf: SpinMutex<[u8; UART_TX_BUF_SIZE]> = SpinMutex::new([0u8; UART_TX_BUF_SIZE]);
 /// Write next to uart_tx_buf[uart_tx_w % UART_TX_BUF_SIZE]
-static mut uart_tx_w: u64 = 0;
+static mut uart_tx_w: usize = 0;
 /// Read next from uart_tx_buf[uart_tx_r % UART_TX_BUF_SIZE]
-static mut uart_tx_r: u64 = 0;
+static mut uart_tx_r: usize = 0;
 
 pub(crate) unsafe fn uartinit() {
     // Disable interrupts.
-    write_register(IER, 0x00);
+    Register::InterruptEnable.write(0x00);
     // Special mode to set baud rate.
-    write_register(LCR, LCR_BAUD_LATCH);
-    // LSB for baud rate of 38.4K.
-    write_register(0u8, 0x03);
-    // MSB for baud rate of 38.4K.
-    write_register(1u8, 0x00);
+    Register::LineControl.write(LCR_BAUD_LATCH);
+    unsafe {
+        // LSB for baud rate of 38.4K.
+        *(UART0 as *mut u8) = 0x03;
+        // MSB for baud rate of 38.4K.
+        *((UART0 + 1) as *mut u8) = 0x00;
+    }
     // Leave set-baud mode and set
     // word length to 8 bits, no parity.
-    write_register(LCR, LCR_EIGHT_BITS);
+    Register::LineControl.write(LCR_EIGHT_BITS);
     // Reset and enable FIFOs.
-    write_register(FCR, FCR_FIFO_ENABLE | FCR_FIFO_CLEAR);
+    Register::FIFOControl.write(FCR_FIFO_ENABLE | FCR_FIFO_CLEAR);
     // Enable transmit and receive interrupts.
-    write_register(IER, IER_TX_ENABLE | IER_RX_ENABLE);
+    Register::InterruptEnable.write(IER_TX_ENABLE | IER_RX_ENABLE);
 
     uart_tx_lock = Spinlock::new(
         CStr::from_bytes_with_nul(b"uart\0")
@@ -97,8 +155,10 @@ pub(crate) unsafe fn uartinit() {
 /// Because it may block, it can't be called
 /// from interrupts, it's only suitable for use
 /// by write().
-pub(crate) unsafe fn uartputc(c: i32) {
+pub(crate) unsafe fn uartputc(c: u8) {
     uart_tx_lock.lock();
+    // let mut buf = uart_tx_buf.lock();
+    // let u = uart.lock();
 
     if crate::PANICKED {
         loop {
@@ -115,7 +175,7 @@ pub(crate) unsafe fn uartputc(c: i32) {
         );
     }
 
-    uart_tx_buf[(uart_tx_w % UART_TX_BUF_SIZE) as usize] = c as i8 as u8;
+    uart_tx_buf[(uart_tx_w % UART_TX_BUF_SIZE) as usize] = c;
     uart_tx_w += 1;
     uartstart();
     uart_tx_lock.unlock();
@@ -125,21 +185,22 @@ pub(crate) unsafe fn uartputc(c: i32) {
 /// use interrupts, for use by kernel printf() and
 /// to echo characters. It spins waiting for the UART's
 /// output register to be empty.
-pub(crate) unsafe fn uartputc_sync(c: i32) {
+pub(crate) unsafe fn uartputc_sync(c: u8) {
     push_off();
+    Uart::write_byte_sync(c);
 
-    if crate::PANICKED {
-        loop {
-            core::hint::spin_loop();
-        }
-    }
+    // if crate::PANICKED {
+    //     loop {
+    //         core::hint::spin_loop();
+    //     }
+    // }
 
-    // Wait for Transmit Holding Empty to be set in LSR.
-    while read_register(LSR) & LSR_TX_IDLE == 0 {
-        core::hint::spin_loop();
-    }
+    // // Wait for Transmit Holding Empty to be set in LSR.
+    // while Register::LineStatus.read() & LSR_TX_IDLE == 0 {
+    //     core::hint::spin_loop();
+    // }
 
-    write_register(THR, c as i8 as u8);
+    // Register::TransmitHolding.write(c);
 
     pop_off();
 }
@@ -154,47 +215,45 @@ unsafe fn uartstart() {
             // Transmit buffer is ready.
             return;
         }
-
-        if read_register(LSR) & LSR_TX_IDLE == 0 {
+        if Register::LineStatus.read() & LSR_TX_IDLE == 0 {
             // The UART transmit holding register is full,
             // so we cannot give it another byte.
             // It will interrupt when it's ready for a new byte.
             return;
         }
 
+        // let buf = uart_tx_buf.lock();
         let c = uart_tx_buf[(uart_tx_r % UART_TX_BUF_SIZE) as usize];
         uart_tx_r += 1;
 
         // Maybe uartputc() is waiting for space in the buffer.
         wakeup(addr_of_mut!(uart_tx_r).cast());
 
-        write_register(THR, c);
+        Register::TransmitHolding.write(c);
     }
 }
 
-/// Read one input character from the UART.
-/// Return -1 if nothing is waiting.
-unsafe fn uartgetc() -> i32 {
-    if read_register(LSR) & 0x01 != 0 {
+/// Read one input byte from the UART.
+pub(crate) fn uartgetc() -> Option<u8> {
+    if Register::LineStatus.read() & 0x01 != 0 {
         // Input data is ready.
-        read_register(RHR) as i32
+        Some(Register::ReceiveHolding.read())
     } else {
-        -1
+        None
     }
 }
 
 /// Handle a UART interrupt, raised because input has
 /// arrived, or the uart is ready for more output, or
 /// both. Called from devintr().
-#[no_mangle]
-pub unsafe extern "C" fn uartintr() {
+pub(crate) unsafe fn uartintr() {
     // Read and process incoming characters.
     loop {
-        let c = uartgetc();
-        if c == -1 {
+        if let Some(c) = uartgetc() {
+            consoleintr(c);
+        } else {
             break;
         }
-        consoleintr(c);
     }
 
     // Send buffered characters.