trying to add atomic implementations in rv32, but still buggy

kernel/riscv32-blog_os.json

@@ -9,7 +9,7 @@
   "cpu": "generic-rv32",
   "features": "",
   "max-atomic-width": "32",
-  "linker": "riscv64-unknown-elf-ld",
+  "linker": "riscv32-unknown-elf-ld",
   "linker-flavor": "ld",
   "pre-link-args": {
     "ld": [

kernel/src/arch/riscv32/compiler_rt.rs

@@ -28,37 +28,51 @@ use core::ptr::{read, write};
 
 #[no_mangle]
 pub unsafe extern fn __atomic_load_1(src: *const u8) -> u8 {
-    read(src)
+    let mut res: u8 = 0;
+    asm!("amoadd.w.rl $0, zero, ($1)" : "=r"(res) : "r"(src) : "memory" : "volatile");
+    res
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_load_2(src: *const u16) -> u16 {
-    read(src)
+    let mut res: u16 = 0;
+    asm!("amoadd.w.rl $0, zero, ($1)" : "=r"(res) : "r"(src) : "memory" : "volatile");
+    res
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_load_4(src: *const u32) -> u32 {
-    read(src)
+    let mut res: u32 = 0;
+    asm!("amoadd.w.rl $0, zero, ($1)" : "=r"(res) : "r"(src) : "memory" : "volatile");
+    res
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_store_1(dst: *mut u8, val: u8) {
-    write(dst, val)
+    asm!("amoswap.w.aq zero, $0, ($1)" :: "r"(val), "r"(dst) : "memory" : "volatile");
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_store_4(dst: *mut u32, val: u32) {
-    write(dst, val)
+    asm!("amoswap.w.aq zero, $0, ($1)" :: "r"(val), "r"(dst) : "memory" : "volatile");
 }
 
 unsafe fn __atomic_compare_exchange<T: PartialEq>(dst: *mut T, expected: *mut T, desired: T) -> bool {
-    use super::interrupt;
+    // use super::interrupt;
-    let flags = interrupt::disable_and_store();
+    // let flags = interrupt::disable_and_store();
-    let val = read(dst);
+    // let val = read(dst);
-    let success = val == read(expected);
+    // let success = val == read(expected);
-    write(dst, if success {desired} else {val});
+    // write(dst, if success {desired} else {val});
-    interrupt::restore(flags);
+    // interrupt::restore(flags);
-    success
+    // success
+    let mut val: T;
+    asm!("lr.w $0, ($1)" : "=r"(val) : "r"(dst) : "memory" : "volatile");
+    if val == *expected {
+        let mut sc_ret = 0;
+        asm!("sc.w $0, $1, ($2)" : "=r"(sc_ret) : "r"(desired), "r"(dst) : "memory" : "volatile");
+        return sc_ret == 0
+    }
+    false
 }
 
 #[no_mangle]

kernel/src/logging.rs

@@ -1,5 +1,8 @@
 use core::fmt;
 use log::{self, Level, LevelFilter, Log, Metadata, Record};
+use spin::Mutex;
+
+static log_mutex: Mutex<()> = Mutex::new(());
 
 pub fn init() {
     static LOGGER: SimpleLogger = SimpleLogger;
@@ -38,11 +41,13 @@ macro_rules! with_color {
 
 fn print_in_color(args: fmt::Arguments, color: Color) {
     use arch::io;
+    let mutex = log_mutex.lock();
     io::putfmt(with_color!(args, color));
 }
 
 pub fn print(args: fmt::Arguments) {
     use arch::io;
+    let mutex = log_mutex.lock();
     io::putfmt(args);
 }