Replace llvm_asm! with asm

os/src/loader.rs

@@ -57,7 +57,7 @@ pub fn load_apps() {
         core::slice::from_raw_parts(num_app_ptr.add(1), num_app + 1)
     };
     // clear i-cache first
-    unsafe { llvm_asm!("fence.i" :::: "volatile"); }
+    unsafe { asm!("fence.i"); }
     // load apps
     for i in 0..num_app {
         let base_i = get_base_i(i);

os/src/main.rs

@@ -1,7 +1,7 @@
 #![no_std]
 #![no_main]
 #![feature(global_asm)]
-#![feature(llvm_asm)]
+#![feature(asm)]
 #![feature(panic_info_message)]
 
 #[macro_use]

os/src/sbi.rs

@@ -14,11 +14,12 @@ const SBI_SHUTDOWN: usize = 8;
 fn sbi_call(which: usize, arg0: usize, arg1: usize, arg2: usize) -> usize {
     let mut ret;
     unsafe {
-        llvm_asm!("ecall"
-            : "={x10}" (ret)
-            : "{x10}" (arg0), "{x11}" (arg1), "{x12}" (arg2), "{x17}" (which)
-            : "memory"
-            : "volatile"
+        asm!(
+            "ecall",
+            inlateout("x10") arg0 => ret,
+            in("x11") arg1,
+            in("x12") arg2,
+            in("x17") which,
         );
     }
     ret