Update rustc && rustsbi; llvm_asm -> asm

rust-toolchain

@@ -1 +1 @@
-nightly
+nightly-2021-08-25

user/src/lib.rs

@@ -1,5 +1,5 @@
 #![no_std]
-#![feature(llvm_asm)]
+#![feature(asm)]
 #![feature(linkage)]
 #![feature(panic_info_message)]
 

user/src/syscall.rs

@@ -5,11 +5,12 @@ const SYSCALL_YIELD: usize = 124;
 fn syscall(id: usize, args: [usize; 3]) -> isize {
     let mut ret: isize;
     unsafe {
-        llvm_asm!("ecall"
-            : "={x10}" (ret)
-            : "{x10}" (args[0]), "{x11}" (args[1]), "{x12}" (args[2]), "{x17}" (id)
-            : "memory"
-            : "volatile"
+        asm!(
+            "ecall",
+            inlateout("x10") args[0] => ret,
+            in("x11") args[1],
+            in("x12") args[2],
+            in("x17") id
         );
     }
     ret