added workaround for atomic ops

kernel/Makefile

@@ -77,6 +77,7 @@ endif
 ld := $(prefix)ld
 objdump := $(prefix)objdump
 cc := $(prefix)gcc
+CC := $(cc)
 as := $(prefix)as
 
 .PHONY: all clean run build asm doc justrun kernel

kernel/build.rs

@@ -12,6 +12,12 @@ fn main() {
 //			.compile("cobj");
 		gen_vector_asm().unwrap();
 	}
+	if std::env::var("TARGET").unwrap().find("riscv32").is_some() {
+		cc::Build::new()
+			.file("src/arch/riscv32/compiler_rt.c")
+			.flag("-march=rv32ima")
+			.compile("atomic_rt");
+	}
 }
 
 fn gen_vector_asm() -> Result<()> {

kernel/src/arch/riscv32/compiler_rt.c

@@ -0,0 +1,57 @@
+
+
+// fn __atomic_load_1_workaround(src: *const u8) -> u8;
+// fn __atomic_load_2_workaround(src: *const u16) -> u16;
+// fn __atomic_load_4_workaround(src: *const u32) -> u32;
+// fn __atomic_store_1_workaround(dst: *mut u8, val: u8);
+// fn __atomic_store_4_workaround(dst: *mut u32, val: u32);
+// fn __atomic_compare_exchange_1_workaround(dst: *mut u8, expected: *mut u8, desired: u8) -> bool;
+// fn __atomic_compare_exchange_4_workaround(dst: *mut u32, expected: *mut u32, desired: u32) -> bool;
+
+char __atomic_load_1_workaround(char *src) {
+    char res = 0;
+    __asm__ __volatile__("amoadd.w.rl %0, zero, (%1)" : "=r"(res) : "r"(src) : "memory");
+    return res; 
+}
+
+short __atomic_load_2_workaround(short *src) {
+    short res = 0;
+    __asm__ __volatile__("amoadd.w.rl %0, zero, (%1)" : "=r"(res) : "r"(src) : "memory");
+    return res; 
+}
+
+int __atomic_load_4_workaround(int *src) {
+    int res = 0;
+    __asm__ __volatile__("amoadd.w.rl %0, zero, (%1)" : "=r"(res) : "r"(src) : "memory");
+    return res; 
+}
+
+char __atomic_store_1_workaround(char *dst, char val) {
+    __asm__ __volatile__("amoswap.w.aq zero, %0, (%1)" :: "r"(val), "r"(dst) : "memory");
+}
+
+int __atomic_store_4_workaround(int *dst, int val) {
+    __asm__ __volatile__("amoswap.w.aq zero, %0, (%1)" :: "r"(val), "r"(dst) : "memory");
+}
+
+char __atomic_compare_exchange_1_workaround(char* dst, char* expected, char desired) {
+    char val = 0;
+    __asm__ __volatile__("lr.w %0, (%1)" : "=r"(val) : "r"(dst) : "memory");
+    if (val == *expected) {
+        int sc_ret = 0;
+        __asm__ __volatile__("sc.w %0, %1, (%2)" : "=r"(sc_ret) : "r"(desired), "r"(dst) : "memory");
+        return sc_ret == 0;
+    }
+    return 0;
+}
+
+char __atomic_compare_exchange_4_workaround(int* dst, int* expected, int desired) {
+    int val = 0;
+    __asm__ __volatile__("lr.w %0, (%1)" : "=r"(val) : "r"(dst) : "memory");
+    if (val == *expected) {
+        int sc_ret = 0;
+        __asm__ __volatile__("sc.w %0, %1, (%2)" : "=r"(sc_ret) : "r"(desired), "r"(dst) : "memory");
+        return sc_ret == 0;
+    }
+    return 0;
+}

kernel/src/arch/riscv32/compiler_rt.rs

@@ -2,6 +2,17 @@
 //!
 //! [atomic](http://llvm.org/docs/Atomics.html#libcalls-atomic)
 
+#[link(name = "atomic_rt")]
+extern {
+    fn __atomic_load_1_workaround(src: *const u8) -> u8;
+    fn __atomic_load_2_workaround(src: *const u16) -> u16;
+    fn __atomic_load_4_workaround(src: *const u32) -> u32;
+    fn __atomic_store_1_workaround(dst: *mut u8, val: u8);
+    fn __atomic_store_4_workaround(dst: *mut u32, val: u32);
+    fn __atomic_compare_exchange_1_workaround(dst: *mut u8, expected: *mut u8, desired: u8) -> bool;
+    fn __atomic_compare_exchange_4_workaround(dst: *mut u32, expected: *mut u32, desired: u32) -> bool;
+}
+
 /// Copy from:
 /// https://github.com/rust-lang-nursery/compiler-builtins/blob/master/src/riscv32.rs
 #[no_mangle]
@@ -28,59 +39,53 @@ use core::ptr::{read, write};
 
 #[no_mangle]
 pub unsafe extern fn __atomic_load_1(src: *const u8) -> u8 {
-    let mut res: u8 = 0;
-    asm!("amoadd.w.rl $0, zero, ($1)" : "=r"(res) : "r"(src) : "memory" : "volatile");
-    res
+    __atomic_load_1_workaround(src)
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_load_2(src: *const u16) -> u16 {
-    let mut res: u16 = 0;
-    asm!("amoadd.w.rl $0, zero, ($1)" : "=r"(res) : "r"(src) : "memory" : "volatile");
-    res
+    __atomic_load_2_workaround(src)
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_load_4(src: *const u32) -> u32 {
-    let mut res: u32 = 0;
-    asm!("amoadd.w.rl $0, zero, ($1)" : "=r"(res) : "r"(src) : "memory" : "volatile");
-    res
+    __atomic_load_4_workaround(src)
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_store_1(dst: *mut u8, val: u8) {
-    asm!("amoswap.w.aq zero, $0, ($1)" :: "r"(val), "r"(dst) : "memory" : "volatile");
+    __atomic_store_1_workaround(dst, val);
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_store_4(dst: *mut u32, val: u32) {
-    asm!("amoswap.w.aq zero, $0, ($1)" :: "r"(val), "r"(dst) : "memory" : "volatile");
+    __atomic_store_4_workaround(dst, val);
 }
 
-unsafe fn __atomic_compare_exchange<T: PartialEq>(dst: *mut T, expected: *mut T, desired: T) -> bool {
-    // use super::interrupt;
-    // let flags = interrupt::disable_and_store();
-    // let val = read(dst);
-    // let success = val == read(expected);
-    // write(dst, if success {desired} else {val});
-    // interrupt::restore(flags);
-    // 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
-}
+// unsafe fn __atomic_compare_exchange<T: PartialEq>(dst: *mut T, expected: *mut T, desired: T) -> bool {
+//     // use super::interrupt;
+//     // let flags = interrupt::disable_and_store();
+//     // let val = read(dst);
+//     // let success = val == read(expected);
+//     // write(dst, if success {desired} else {val});
+//     // interrupt::restore(flags);
+//     // 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]
 pub unsafe extern fn __atomic_compare_exchange_1(dst: *mut u8, expected: *mut u8, desired: u8) -> bool {
-    __atomic_compare_exchange(dst, expected, desired)
+    __atomic_compare_exchange_1_workaround(dst, expected, desired)
 }
 
 #[no_mangle]
 pub unsafe extern fn __atomic_compare_exchange_4(dst: *mut u32, expected: *mut u32, desired: u32) -> bool {
-    __atomic_compare_exchange(dst, expected, desired)
+    __atomic_compare_exchange_4_workaround(dst, expected, desired)
 }

kernel/src/logging.rs

@@ -1,8 +1,10 @@
 use core::fmt;
 use log::{self, Level, LevelFilter, Log, Metadata, Record};
-use spin::Mutex;
+use sync::SpinLock as Mutex;
 
-static log_mutex: Mutex<()> = Mutex::new(());
+lazy_static! {
+    static ref log_mutex: Mutex<()> = Mutex::new(());
+}
 
 pub fn init() {
     static LOGGER: SimpleLogger = SimpleLogger;

kernel/src/sync/arch/riscv32/atomic_lock.rs

@@ -0,0 +1,40 @@
+//! RISCV atomic is not currently supported by Rust.
+//! This is a ugly workaround.
+
+
+use arch::compiler_rt::{__atomic_compare_exchange_4, __atomic_store_4, __atomic_load_4};
+use core::cell::UnsafeCell;
+
+pub struct AtomicLock
+{
+    lock: UnsafeCell<u32>
+}
+
+impl AtomicLock 
+{
+    pub fn new() -> Self {
+        AtomicLock {
+            lock: UnsafeCell::new(0)
+        }
+    }
+
+    /// Returns 1 if lock is acquired
+    pub fn try_lock(&self) -> bool {
+        let mut expected: u32 = 0;
+        unsafe {
+            __atomic_compare_exchange_4(self.lock.get(), &mut expected as *mut u32, 1)
+        }
+    }
+
+    pub fn load(&self) -> bool {
+        unsafe {
+            __atomic_load_4(self.lock.get()) == 1
+        }
+    }
+
+    pub fn store(&self) {
+        unsafe {
+            __atomic_store_4(self.lock.get(), 0);
+        }
+    }
+}

kernel/src/sync/arch/x86_64/atomic_lock.rs

@@ -0,0 +1,30 @@
+
+pub struct AtomicLock
+{
+    lock: usize
+}
+
+impl AtomicLock 
+{
+    pub fn new() -> AtomicLock {
+        AtomicLock {
+            lock: ATOMIC_BOOL_INIT
+        }
+    }
+
+    pub fn try_lock(&self) -> bool {
+        self.lock.compare_and_swap(false, true, Ordering::Acquire) == false
+    }
+
+    pub fn load(&self) -> bool {
+        self.lock.load(Ordering::Relaxed)
+    }
+
+    pub fn store(&self) {
+        self.lock.store(false, Ordering::Release);
+    }
+}
+
+pub const ATOMIC_LOCK_INIT: AtomicLock = AtomicLock {
+    lock: ATOMIC_BOOL_INIT
+};

kernel/src/sync/mod.rs

@@ -53,6 +53,15 @@ pub use self::condvar::*;
 pub use self::mutex::*;
 pub use self::semaphore::*;
 
+#[allow(dead_code)]
+#[cfg(target_arch = "x86_64")]
+#[path = "arch/x86_64/atomic_lock.rs"]
+pub mod atomic_lock;
+
+#[cfg(target_arch = "riscv32")]
+#[path = "arch/riscv32/atomic_lock.rs"]
+pub mod atomic_lock;
+
 mod mutex;
 mod condvar;
 mod semaphore;

kernel/src/sync/mutex.rs

@@ -30,8 +30,8 @@ use arch::interrupt;
 use core::cell::UnsafeCell;
 use core::fmt;
 use core::ops::{Deref, DerefMut};
-use core::sync::atomic::{ATOMIC_BOOL_INIT, AtomicBool, Ordering};
 use super::Condvar;
+use super::atomic_lock::AtomicLock;
 
 pub type SpinLock<T> = Mutex<T, Spin>;
 pub type SpinNoIrqLock<T> = Mutex<T, SpinNoIrq>;
@@ -39,7 +39,7 @@ pub type ThreadLock<T> = Mutex<T, Condvar>;
 
 pub struct Mutex<T: ?Sized, S: MutexSupport>
 {
-    lock: AtomicBool,
+    lock: AtomicLock,
     support: S,
     data: UnsafeCell<T>,
 }
@@ -78,7 +78,7 @@ impl<T, S: MutexSupport> Mutex<T, S>
     /// ```
     pub fn new(user_data: T) -> Mutex<T, S> {
         Mutex {
-            lock: ATOMIC_BOOL_INIT,
+            lock: AtomicLock::new(),
             data: UnsafeCell::new(user_data),
             support: S::new(),
         }
@@ -96,9 +96,9 @@ impl<T, S: MutexSupport> Mutex<T, S>
 impl<T: ?Sized, S: MutexSupport> Mutex<T, S>
 {
     fn obtain_lock(&self) {
-        while self.lock.compare_and_swap(false, true, Ordering::Acquire) != false {
+        while !self.lock.try_lock() {
             // Wait until the lock looks unlocked before retrying
-            while self.lock.load(Ordering::Relaxed) {
+            while self.lock.load() {
                 self.support.cpu_relax();
             }
         }
@@ -137,14 +137,14 @@ impl<T: ?Sized, S: MutexSupport> Mutex<T, S>
     ///
     /// If the lock isn't held, this is a no-op.
     pub unsafe fn force_unlock(&self) {
-        self.lock.store(false, Ordering::Release);
+        self.lock.store();
     }
 
     /// Tries to lock the mutex. If it is already locked, it will return None. Otherwise it returns
     /// a guard within Some.
     pub fn try_lock(&self) -> Option<MutexGuard<T, S>> {
         let support_guard = S::before_lock();
-        if self.lock.compare_and_swap(false, true, Ordering::Acquire) == false {
+        if self.lock.try_lock() {
             Some(MutexGuard {
                 mutex: self,
                 support_guard,
@@ -186,7 +186,7 @@ impl<'a, T: ?Sized, S: MutexSupport> Drop for MutexGuard<'a, T, S>
 {
     /// The dropping of the MutexGuard will release the lock it was created from.
     fn drop(&mut self) {
-        self.mutex.lock.store(false, Ordering::Release);
+        self.mutex.lock.store();
         self.mutex.support.after_unlock();
     }
 }